# Improve That Design: How Aircraft Could Have Been Made Better



## Zipper730 (May 28, 2019)

It's an intellectual exercise, revolving around how aircraft could have been made better with technology available at the time around either

The existing specification: Basically, the idea would be working within the existing specification, but you could modify or change anything within the boundary of it.
A different winner: Sometimes the problem wasn't the design so much as the winner to the contender: While way after WWII, many feel the YF-23 should have won over the YF-22, for example.
A more realistic/practical specification: Basically the specifications are made more realistic to allow a practical design to be developed, an example would be the He-177 having 4 x DB-601's instead of 2 x DB-606's, or simply not being designed as a dive-bomber.
I would assume that the changes could include differences in aerodynamics, in installation of existing equipment, in propulsion system where applicable and allowable. I guess conceptual designs that didn't fly could also be included.

To start off: Aircraft that I could imagine huge improvements within the existing specification would be

Y1P-37: The engine and turbocharger arrangement seemed okay, the problem was that the radiator and intercooler system producing an airplane that had the cockpit so far back taxiing would be a royal pain in the butt, and aerial combat could be disastrous.
He-177: The basic design was fundamentally solid and, had it simply had 4 x DB601's instead of 2 x DB606's, or just not been built around dive-bombing specifications, it'd be fine.
XP-61E: Either with an R-2800 used on the F4U-4 or a turbocharged variant would have put the plane's speed high enough to be a formidable fighter.
There are probably many others.

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## swampyankee (May 28, 2019)

P-61A:

Eliminate the gunner and the turret. Put the pilot and radar operator under a tandem canopy, that is jump right to the P-61E configuration. Getting rid of the turret and gunner would probably save close to a ton in empty weight, twenty percent in zero-lift drag, and months in development

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## Greg Boeser (May 28, 2019)

B-26 Marauder 
*Go with the longer wing right from the start. 
Fowler flaps.
*Redesign the bomb bay doors to eliminate drag. (Folding doors caused massive drag when open, reducing top speed by 25 mph.) Roll up doors like on B-24 were suggested, but never implemented.
Redesign bomb bay with capacity for tandem racks, thus eliminating need for second bomb bay. I was shocked at how much space was wasted when carrying smaller bombs.
*Move turret forward to improve CG.
Add RADAR. 

*indicates a proposal that was not implemented

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## wuzak (May 28, 2019)

This is loking a lot like an earlier thread

This is the way it should have been from the beginning....

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## Zipper730 (May 28, 2019)

swampyankee said:


> P-61A: Eliminate the gunner and the turret. Put the pilot and radar operator under a tandem canopy, that is jump right to the P-61E configuration. Getting rid of the turret and gunner would probably save close to a ton in empty weight, twenty percent in zero-lift drag, and months in development


I agree with the idea. I'm curious why the British were so obsessed with the idea.

I get the basic concept: Schrage Music with Options -- you could rake 'em from below if you couldn't get above them. The fact is that powered turrets (remote controlled or directly manned) take up weight and impose a drag penalty that you'd be best without. Admittedly, I was told the P-61 only gained a few miles an hour with the turret removed, but with the structure totally reconfigured more like the XP-61E, I could easily see the performance figures going up.

If drag also lowers, so too will climb-rate...

One thing that I remember being rather interesting with the P-61 was a desire for an 8 hour endurance, so as to loiter over a city all night long. Some say the idea came from General Emmons, others say it came from either Northrop himself or Vladimir Pavlecka. I'm curious if that was even possible.



wuzak said:


> This is loking a lot like an earlier thread
> 
> This is the way it should have been from the beginning....


I actually forgot about that thread. Since this thread doesn't seem to have much activity for the past year (almost exactly, actually), I'm curious if it would be best to amalgamate these two threads, or just let this thread run in lieu of the older one?


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## Shortround6 (May 29, 2019)

Greg Boeser said:


> B-26 Marauder
> *Go with the longer wing right from the start.
> Fowler flaps.
> *Redesign the bomb bay doors to eliminate drag. (Folding doors caused massive drag when open, reducing top speed by 25 mph.) Roll up doors like on B-24 were suggested, but never implemented.
> ...



Very few bombers could carry the same weight of "small" bombs as large ones. _Small being under 250lbs_. even an He 111 dropped from 4400lbs carrying eight 250kg bombs to 3520lbs carrying thirty two 50kg bombs and they managed to stuff four 50kg bombs in each 250kg bomb cell. 

Hanging them on individual racks really sucks up room. In part due to the needs of hoisting bombs into position and the needs of the armorers to work around the bombs fitting fuses and safety wires. 

AIrplanes have two CG or perhaps weight distribution problems is a better way of saying it. The first is flying and most of us are familiar with that. The second is landing and/or ground handling. Once a number of planes were modified with extra armament or operational equipment they managed to keep the flying CG pretty much in place but the ever increasing loads often strained the landing gear or made ground handling difficult. Pilots manual for even the B-25C/D prohibits pivot turns, notes that on soft surfaces the nose wheel can dig in a reverse itself (turn 180 degrees) if the tire sinks more than 2 inches into the soil. It suggests having a crew man walk in front of the plane monitoring the wheel if the ground is soft. 

On some planes it was a trade off between more effective armament (or more effective placement) and increase ground accidents/ even if repairable. 

On the B-26 they added tons of equipment/consumables to the original design. Moving the turret forward (to behind the pilots? ) would seem doable, but they were adding a single fixed .50 in the nose and the four cheek guns, Perhaps they needed the turret to stay where it was? 
Of course they added more/bigger lower waist guns and an extra crewman? so perhaps moving the turret would help with that? B-26 went through a lot of weight shifts.

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## GrauGeist (May 30, 2019)

With any german bomber (He177 included), eliminate the requirement for dive-bombing.
They had the Hs123, Ju87 and Hs132 for dedicated dive-bombing (although the Hs132 didn't have time to go operational) as well as the Fw190F for that role. The Ju88 would be the exception to the rule, as it did well in that capacity.

The RLM's obsession with dive-bombing cost a great deal of time and effort for such little return.

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## wuzak (May 30, 2019)

I can't remember if the He 177 was originally proposed and designed without provision for dive bombing, but the requirement for dive bombing was added later causing delays and structural issues.


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## GrauGeist (May 30, 2019)

wuzak said:


> I can't remember if the He 177 was originally proposed and designed without provision for dive bombing, but the requirement for dive bombing was added later causing delays and structural issues.


It was not part of the original design and when the RLM insisted on it being capable, it caused a great deal of lost time and energy trying to make it capable. The Do217 was also made dive-bomb capable during the "E" variant production. Other bombers with the requirement: Fw191 and Ju188. 

The obsession was not just limited to bombers, however, they pulled that stunt on several promising heavy fighter types like the Ar240, too.

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## Zipper730 (May 30, 2019)

GrauGeist said:


> With any german bomber (He177 included), eliminate the requirement for dive-bombing.
> They had the Hs123, Ju87 and Hs132 for dedicated dive-bombing (although the Hs132 didn't have time to go operational) as well as the Fw190F for that role. The Ju88 would be the exception to the rule, as it did well in that capacity.


Agreed



wuzak said:


> I can't remember if the He 177 was originally proposed and designed without provision for dive bombing, but the requirement for dive bombing was added later causing delays and structural issues.


From what I remember, the He-177 was designed originally for the ability to perform low to moderate angle dive-bombing, and after the Spanish Civil War, the requirement was changed to a 60-degree dive-capability.

I'm not sure what low/moderate angle diving attacks mean, but if dive-bombing is over 60-degrees, and low was 0-30, and medium was 30-60, I wouldn't be surprised if 30-45 would be about what they were looking for. It was ambitious enough.


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## GrauGeist (May 30, 2019)

The He177 was purely conceived as a strategic heavy bomber in answer to the RLM's "Bomber A" program, which would have seen it penetrate into Soviet airspace to strike industrial targets.

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## PAT303 (May 30, 2019)

I would have liked to have seen the Spit reach it's full potential. The interim models were needed, MkV-IX-XIV but I can't help but think the blooding of the spit in 1941-42 by the likes of the FW190A would not have happened if the MkIII running 2 stage Merlin XX's could have been made.

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## drgondog (May 30, 2019)

PAT303 said:


> I would have liked to have seen the Spit reach it's full potential. The interim models were needed, MkV-IX-XIV but I can't help but think the blooding of the spit in 1941-42 by the likes of the FW190A would not have happened if the MkIII running 2 stage Merlin XX's could have been made.


Impossible development cycle, the Merlin 61 was introduced as early as possible and not available in quantity until mid 1943. Early releases for the Spitfire IX were in squadron level in very late 1942. The P-51B could not have been deployed to ETO more than 1-2 months earlier due to the Packard bug fixing, then the Packard strike.

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## Kevin J (May 30, 2019)

PAT303 said:


> I would have liked to have seen the Spit reach it's full potential. The interim models were needed, MkV-IX-XIV but I can't help but think the blooding of the spit in 1941-42 by the likes of the FW190A would not have happened if the MkIII running 2 stage Merlin XX's could have been made.


The Merlin 45 was a derivative of the Merlin XX. It had the high altitude but not the low altitude performance. So what's wrong with what was done? Putting the Merlin XX into the Hurricane kept it competitive at all altitudes. It was a rugged fighter that could be deployed across the globe. Its aerial victory statistics back the decision up. The Spitfire was less rugged, scored fewer kills, and was not really deployable on the global scale until the Vc version.


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## wuzak (May 30, 2019)

drgondog said:


> Impossible development cycle, the Merlin 61 was introduced as early as possible and not available in quantity until mid 1943. Early releases for the Spitfire IX were in squadron level in very late 1942. The P-51B could not have been deployed to ETO more than 1-2 months earlier due to the Packard bug fixing, then the Packard strike.



The Spitfire III had the 2 speed Melin XX, not the 2 stage Merlin 61. It also had some airframe improvements, including retracting tail gear, clipped wings and improved radiator ducts. First flight was March 15, 1940. Maximum speed was 400mph @ 21,000ft with the Merlin X. The Merlin X was to be used for initial production aircraft until Merlin XX production was up to speed.

The prototype Mk III was delivered to Rolls-Royce for use as an engine test bed for the Merlin 60 in April 1941, making its first flight on 27 September 1941. Basically it was the prototype for the IX/VIII.

A Spitfire Mk I was delivered for conversion on 13 October 1941 and first flew on 6 January 1942. 

Two Mk Vs were delivered to Rolls-Royce on 7 and 12 December 1941, one flying on 26 February 1942 and the other on 27 March 1942.

More Spitfire Vs were delivered as trials aircraft and 100 Spitfire IXs were ordered from Supermarine to be delivered by the end of June 1942.

Supermarine built 52 Spitfire IXs and Rolls-Royce 48.

No.64 squadron was equipped with the Spitfire IX in June 1942, No.611 in July and Nos. 401 and 402 in August. All four squadrons participated in Operation Jubilee, the Dieppe Raid. This was also the first combat operations for the Mustang I.

Note that PAT303 made no mention of the P-51B.

When production of Spitfire IXs started at Castle Bromwich they were fitted with Merlin 63s. 

The first Spitfire LF.IX conversion to Merlin 66 by Rolls-Royce was in May 1943. The first HF.IX with Merlin 70 was later in the year (~September).

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## wuzak (May 30, 2019)

Kevin J said:


> The Merlin 45 was a derivative of the Merlin XX. It had the high altitude but not the low altitude performance. So what's wrong with what was done? Putting the Merlin XX into the Hurricane kept it competitive at all altitudes. It was a rugged fighter that could be deployed across the globe. Its aerial victory statistics back the decision up. The Spitfire was less rugged, scored fewer kills, and was not really deployable on the global scale until the Vc version.



The Merlin XX had a higher gear for the supercharger in FS gear than the Merlin 45 had for its only gear. Thus it had a higher critical altitude than the 45.

A Merlin XX powered Spitfire would have been more competitive with the Bf 109F-4 and Fw 190A than the Spitfire V was.

The Spitfire was not deployed overseas initially because there weren't enough built that could be used for the home front and deployed overseas. In a shocking decision the Air Ministry/RAF decided to keep Spitfires defending British skies and deployed Hurricanes to what were considered secondary theatres.

The Merlin XX made the Hurricane more competitive, but that's not to say they were truly competitive in the ETO.

And, as I have said before, number of kills speaks more to opportunity than effectiveness.

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## tomo pauk (May 30, 2019)

PAT303 said:


> I would have liked to have seen the Spit reach it's full potential. The interim models were needed, MkV-IX-XIV but I can't help but think the blooding of the spit in 1941-42 by the likes of the FW190A would not have happened if the MkIII running 2 stage Merlin XX's could have been made.



Oh, if only Merlin XX was a two stage engine.



Kevin J said:


> The Merlin 45 was a derivative of the Merlin XX. It had the high altitude but not the low altitude performance. So what's wrong with what was done? Putting the Merlin XX into the Hurricane kept it competitive at all altitudes. It was a rugged fighter that could be deployed across the globe. Its aerial victory statistics back the decision up. The Spitfire was less rugged, scored fewer kills, and was not really deployable on the global scale until the Vc version.



It was not about engine, it was about airframe and timing. Merlin 45 was lagging perhaps 7-8 months behind the XX. Spitfire III have had internal BP glass, retractable & covered tail wheel and covered main wheel well, thus it have had less drag. Add that Spitfire V suffered another 10+- mph loss due to lousy fit and finish and there is no wonder it was 3rd best European fighter by late 1941.
Hurricane IIa (8 Brownings) was competitive in 1940, by early 1941 it was not. It was further tamed once 12 Browings were installed (IIb), let alone once 4 cannons were installed (IIc). 

With regard to the 'improve that design' as applied to the early Spitfires:
- Spitfire I: 4 Vickers HMG, metal ailerons, double sheet central part of the wing (= more rigid = better roll), metal ailerons, pressure injection carb, better exhausts, at least 2-pitch prop.
- Spitfire II: constant speed prop from day one, drop tank facility, internal BP glass
- Spitfire III: as historically more or less


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## tomo pauk (May 30, 2019)

wuzak said:


> The Merlin XX had a higher gear for the supercharger in FS gear than the Merlin 45 had for its only gear. Thus it had a higher critical altitude than the 45.
> ...



IIRC the power was within 1-2% above 18000 ft, both managing about 1200 HP there.


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## tomo pauk (May 30, 2019)

Random Luftwaffe A/C being better the way I see it:
- Bf 109E: 4 HMGs, drop tank from day one
- Bf 109F: 3 cannons
- Fw 190: DB 601 engine from day one + a drop tank or two; move to DB 605 when available, then on DB 603 
- Ju 87: always with a prop cannon
- Ju 88: wings in high/shoulder position so there is a real bomb bay


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## Shortround6 (May 30, 2019)

Zipper730 said:


> revolving around how aircraft could have been made better with technology available at the time around either



Now, does that mean guns that didn't exist (but could be made with existing technology?) 
Engines that wouldn't exist for a year or more? 

and so on. 

The British didn't have a suitable HMG in the late 30s or 1940, perhaps they could have. 
The .5in Vickers was large, heavy and suffered from jams even though it rarely actually broke. (How do you define reliability?) it also didn't have a particularly high rate of fire. 
Provision of truly effective ammo was a problem, No HE rounds and good incendiaries only came later? 

Of course the Germans didn't have a heavy machine gun either in 1939/40. They were working on one but it doesn't really see service until 1941. 

Both the Germans and the British advocates in these retrospective exercises have to be careful not to fall into the trap the US did historically. Over arming the planes for the engines that existed at the time. 
The larger, heavier FW 190 airframe may not have worked very well with a 1940 DB 601 engine  

Same with adding a cannon to early JU 87s. Even with an early Jumo 211 do you want to try sticking a cannon through the prop? and to what purpose?
An MG FF with a 55/60 round drum is certainly not a tank killer. Perhaps you could use that whacking big gun that used 20 X 138 ammo but it weighed 64kg without ammo.

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## tomo pauk (May 30, 2019)

Shortround6 said:


> ...
> The British didn't have a suitable HMG in the late 30s or 1940, perhaps they could have.
> The .5in Vickers was large, heavy and suffered from jams even though it rarely actually broke. (How do you define reliability?) it also didn't have a particularly high rate of fire.
> Provision of truly effective ammo was a problem, No HE rounds and good incendiaries only came later?
> Of course the Germans didn't have a heavy machine gun either in 1939/40. They were working on one but it doesn't really see service until 1941.



There was several British (mostly Vickers-made) HMGs, reliable and all that jazz, that required just a will to adopt to RAF needs by 1930s. link
Of course, both British and Germans can buy licence from USA or Italy in mid-30s.



> Both the Germans and the British advocates in these retrospective exercises have to be careful not to fall into the trap the US did historically. Over arming the planes for the engines that existed at the time.
> The larger, heavier FW 190 airframe may not have worked very well with a 1940 DB 601 engine



Airframe (fuselage, wing, undercarriage, tail, controls & control surfaces) of the Fw 190V1 prototype weighted 760 kg (1765 lbs). Powerplant (engine, prop, cooling cotrols, oil system, cowling) represented around half of in-service Fw 190A's empty equipped weight - 1661 kg (3670 lbs).
Airframe of lightest P-40 ('no letter') went to 2200+ lbs.



> Same with adding a cannon to early JU 87s. Even with an early Jumo 211 do you want to try sticking a cannon through the prop? and to what purpose?
> An MG FF with a 55/60 round drum is certainly not a tank killer. Perhaps you could use that whacking big gun that used 20 X 138 ammo but it weighed 64kg without ammo.



Yes, I want that big whacking gun (roughly size of Hispano II), with 100 rd box, to kill some 'soft' targets - trucks, carriages, artillery. Ju 87 was no slouch in carrying ordnance, even with the earliest Jumo 211.


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## Kevin J (May 30, 2019)

wuzak said:


> The Merlin XX had a higher gear for the supercharger in FS gear than the Merlin 45 had for its only gear. Thus it had a higher critical altitude than the 45.
> 
> A Merlin XX powered Spitfire would have been more competitive with the Bf 109F-4 and Fw 190A than the Spitfire V was.
> 
> ...


Perhaps you can come up with some figures on Hurricane vs Spitfire victories in the UK after the BoB and up to the Dieppe raid. IIRC the Hurricane was still scoring well up to the introduction of the Spitfire Vb even Fw 190A. The Hurricanes supplied to the USSR were operating successfully during the first 5 months of 1942; admittedly no aces unless you include shared victories.


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## tomo pauk (May 30, 2019)

For the 'Muricans:
- P-51 + V-1650-1, ASAP
- P-47 with proper drop tank facility, ASAP
- P-38 as a classic twin, with leading-edge radiators
- P-39 with 20mm + 2 HMGs, two drop tanks
- P-43 with V-1710


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## gomwolf (May 30, 2019)

G.56 + DB603E + MW50 + Leading edge slat.

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## Simon Thomas (May 30, 2019)

Short Stirling + 112' wing span - 9000+ lbs of "good ideas" from the air ministry - 3° incidence by undercarriage extension = rather good bomber


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## tomo pauk (May 30, 2019)

Random bombers:
- B-26 with fuselage tailored around a bomb bay and crew of 5
- pre-Tu-2 with AM-38
- less ambitious Ju 288 with BMW 801, later with DB 603
- A-20 + turbo V-1710


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## Shortround6 (May 30, 2019)

tomo pauk said:


> There was several British (mostly Vickers-made) HMGs, reliable and all that jazz, that required just a will to adopt to RAF needs by 1930s. link


http://www.quarryhs.co.uk/Vickers.html

There was a bit of NIH in that report. The .5 Vickers was just a scaled up .303 Vickers with just about all the advantages and disadvantages. The manual for the .303 Vickers is supposed to list 26 or 27 different "stoppages", many of which can be diagnosed by noting the exact position of the cocking handle and some of which can be cleared with a good thump to the gun and tug or push on the cocking handle, some cannot but are still quickly cleared by a knowledgeable gunner. The Vickers had a very good reputation for durability and rare parts breakage. But it's "reliability" and rate of fire were why the RAF replaced it with the Browning for wing mounted guns. Going back to the Vickers for wing mounted guns may not have worked well. 
The article you referenced uses the wrong ammo information for the .50 cal under test. The 710 grain bullet and 2900fps MV wouldn't exist until about 1940. The British wouldn't get such ammo until later. 



> Of course, both British and Germans can buy licence from USA or Italy in mid-30s.http://www.quarryhs.co.uk/Vickers.html


http://www.quarryhs.co.uk/Vickers.html
In the Mid 30s the US still had the low velocity ammo. The M2 gun with it's improvements might be available instead of the M1924 gun though. 





> Airframe (fuselage, wing, undercarriage, tail, controls & control surfaces) of the Fw 190V1 prototype weighted 760 kg (1765 lbs). Powerplant (engine, prop, cooling cotrols, oil system, cowling) represented around half of in-service Fw 190A's empty equipped weight - 1661 kg (3670 lbs).
> Airframe of lightest P-40 ('no letter') went to 2200+ lbs.



We seem to have a disconnect here. The Fw 190V1 Prototype according to one source (which could be wrong) used a 160sq ft wing and the BMW 139 engine that was 350lbs lighter than the BMW801 ? according to this source the entire structure had to be stressed and strengthened. Normal loaded weight without armament had grown 25% to 7,550lbs (?) and wing loading had grown to 46.6lbs/sq/ft. A new wing of 196.98 sq ft was designed. 





> Yes, I want that big whacking gun (roughly size of Hispano II), with 100 rd box, to kill some 'soft' targets - trucks, carriages, artillery. Ju 87 was no slouch in carrying ordnance, even with the earliest Jumo 211.


The gun only has a limited application. the rate of fire is 300-350rpm or 5-6 rounds per second. The ammunition is somewhat more powerful than the Hispano, but if you are using HE ammo the impact velocity is a lot less important. There was an AP round but once tanks went beyond 14-15 mm armor it's utility dropped considerably. For soft targets you might be better served by an extra MG 17 in each wing, or two. At up to 20 rounds per second per barrel against soft targets the likelihood of getting multiple hits goes way up. An extra pair of MG 17s might see around 8 hits (on top of the hits from the existing wing guns) for every 20mm hit.


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## wuzak (May 30, 2019)

Shortround6 said:


> Perhaps you could use that whacking big gun that used 20 X 138 ammo but it weighed 64kg without ammo.



Is the "whacking big gun" the MG C/30L?


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## Shortround6 (May 30, 2019)

yes, Trying to use an MG FF through the prop of a JU 87 doesn't get you much as armor penetration is pretty crappy. 

The MG C/30L is supposed to have knocked out a few tanks in Spain (3 Russian T-26 tanks?) which had 15mm armor pretty much all around on the vertical surfaces.


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## sdmodeller (May 31, 2019)

Ok how about this one: P-39 with a merlin? Keep it a low level fighter but up the HP. Trash the 37mm and 30 cal. Basically 109F armament. She might a real minx then.

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## wuzak (May 31, 2019)

sdmodeller said:


> Ok how about this one: P-39 with a merlin? Keep it a low level fighter but up the HP. Trash the 37mm and 30 cal. Basically 109F armament. She might a real minx then.



Which Merlin?

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## PAT303 (May 31, 2019)

Kevin J said:


> The Merlin 45 was a derivative of the Merlin XX. It had the high altitude but not the low altitude performance. So what's wrong with what was done? Putting the Merlin XX into the Hurricane kept it competitive at all altitudes. It was a rugged fighter that could be deployed across the globe. Its aerial victory statistics back the decision up. The Spitfire was less rugged, scored fewer kills, and was not really deployable on the global scale until the Vc version.


The MkIII was redesigned using all the lessons learnt from the BOB, as Wuzak posted, the MkIII if built would have been the stand out fighter from 1940 onwards, it would also mean the MkVIII would be the main version instead of the interim Mk IX, in doing so fixing the single biggest downside to the spit, lack of internal fuel.

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## Kevin J (May 31, 2019)

PAT303 said:


> The MkIII was redesigned using all the lessons learnt from the BOB, as Wuzak posted, the MkIII if built would have been the stand out fighter from 1940 onwards, it would also mean the MkVIII would be the main version instead of the interim Mk IX, in doing so fixing the single biggest downside to the spit, lack of internal fuel.


The problem with that in the 1940/41 time period is the maxim 'no changes on the production line' as until the USSR was invaded there was still the danger that the Nazi's will invade. That's why only incremental changes were made to the Spitfire. The Spitfire Va/b aka Ia/b with the Merlin 45/46. I'm not doubting that the Spitfire III was excellent but when would it have entered service. As things were, the first production Vb's didn't arrive until June 1941 although Va's converted by Rolls-Royce from Ia's had begun arriving 3 months earlier. The Spitfire Vc didn't enter service until March / April 1942 and that had only a limited number of the changes from the Spitfire III.


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## Ivan1GFP (May 31, 2019)

Greg Boeser said:


> B-26 Marauder
> *Go with the longer wing right from the start.
> Fowler flaps.
> *Redesign the bomb bay doors to eliminate drag. (Folding doors caused massive drag when open, reducing top speed by 25 mph.) Roll up doors like on B-24 were suggested, but never implemented.
> ...



Hello Greg Boeser,
I believe one of the biggest design flaws of the Marauder was the choice of airfoil.
For a non-aerobatic aircraft, there really wasn't a good reason to use a symmetrical airfoil.
The lack of lift at low AoA eventually resulted in rotating the entire wing along with engines (B-26G) to increase incidence and lift at lower speeds but reduced maximum speed.
With a better high lift airfoil, they would not have had those issues to begin with.

I believe also that the rear bomb bay was simply not a good idea.

Ditching the Curtiss Electric propellers in favour of hydromatics might have resulted in fewer aeroplanes in Tampa Bay and fewer take off accidents. The design wasn't necessary a bad one, but gave too many opportunities for ground crew to screw up in handling APU and battery which resulted in not enough power for the propellers to work correctly.



Shortround6 said:


> AIrplanes have two CG or perhaps weight distribution problems is a better way of saying it. The first is flying and most of us are familiar with that. The second is landing and/or ground handling. Once a number of planes were modified with extra armament or operational equipment they managed to keep the flying CG pretty much in place but the ever increasing loads often strained the landing gear or made ground handling difficult. Pilots manual for even the B-25C/D prohibits pivot turns, notes that on soft surfaces the nose wheel can dig in a reverse itself (turn 180 degrees) if the tire sinks more than 2 inches into the soil. It suggests having a crew man walk in front of the plane monitoring the wheel if the ground is soft.
> 
> On some planes it was a trade off between more effective armament (or more effective placement) and increase ground accidents/ even if repairable.
> 
> ...



Hello Shortround6,
I believe the problem with the Marauder was that the CoG changed too much as equipment was shifted about or removed.
I am sure we have all heard about the case of nose gear collapses due to incorrect CoG resulting from misleading of equipment on the aircraft. The problem there seemed to be CoG too far forward rather than too far aft.

- Ivan.


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## Ivan1GFP (May 31, 2019)

I believe the Mitsubishi A6M Type 0 would have done quite a bit better if the initial design had gone with the Mitsubishi Kinsei engine instead of the Nakajima Sakae. It may not have had quite the same range and agility, but would have stayed as a viable fighter for much longer. 
The Japanese eventually came to the same conclusion when they fitted the Kinsei to the A6M8 but it might have been a whole lot better if it had been done 5 years earlier.

I also believe that the FW 190 series should have gotten an increase in the size of its wing. In the prototype stage, it had already gone from a 160 ft^2 wing to 197 ft^2 wing but weight increased substantially with production models and the size of the wing did not change. It also meant that if not properly flown, it had a tendency to mush.  A wing with increased span may have improved the issue and as seen with the Ta 152 series, it did not drastically affect the roll rate.

Thoughts?
- Ivan.

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## buffnut453 (May 31, 2019)

Shortround6 said:


> In the Mid 30s the US still had the low velocity ammo. The M2 gun with it's improvements might be available instead of the M1924 gun though.



And the 50 cal in wing-mounted installations wasn't working...at least not reliably. Now, I'm sure it could have been fixed sooner that the latter half of 1942, as was the case in reality. Maybe that's an area where multiple US fighters could have been improved faster than the actual timeline?


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## ClayO (May 31, 2019)

Zipper730 said:


> I agree with the idea. I'm curious why the British were so obsessed with the idea.



On the P61's turret: since the British wanted the P61 as a defense against buzz bombs, I've wondered if they wanted a way to shoot them down from some other position than directly behind - which forced the pilot to hit a difficult target from maximum range, then immediately veer away from the explosion on the first hit. It would still be difficult shot, but if the turret had worked, the interceptor could have behind or below the buzz bomb, and so could have been somewhat closer. As it was, the buzz bomb threat was pretty much over with by the time they fixed the turbulence problems caused by turning the turret in flight, so I don't know if there's any data on that.


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## swampyankee (May 31, 2019)

ClayO said:


> On the P61's turret: since the British wanted the P61 as a defense against buzz bombs, I've wondered if they wanted a way to shoot them down from some other position than directly behind - which forced the pilot to hit a difficult target from maximum range, then immediately veer away from the explosion on the first hit. It would still be difficult shot, but if the turret had worked, the interceptor could have behind or below the buzz bomb, and so could have been somewhat closer. As it was, the buzz bomb threat was pretty much over with by the time they fixed the turbulence problems caused by turning the turret in flight, so I don't know if there's any data on that.




Adding the turret, gunner, and associated equipment probably made the performance needed to intercept the V-1 nearly impossible.

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## Shortround6 (May 31, 2019)

The Turret was incorporated almost from the start of design in 1941, well before anybody even knew what a buzz bomb was.

However, in 1940/41 airborne radar was not all it could be and had a minimum range of hundreds of yards which meant the final close to the target was often a visual search, target could appear enough off axis of the aircraft to prevent getting a firing pass, in which case it was hoped the turret could engage the target. 
Preliminary design work started on the P-61 in the fall of 1940 and contract for two prototypes was signed Jan 30th 1941. 
Please not that this perhaps limits both the engine selection and the configuration of the fuselage as Jack Northrop is not really given any details at all on "Radar". He is merely told that
[that there was a way to "see and distinguish other airplanes" ]

so minor details (sarcasm) like volume and weight of this device (or if it needs extra crewmen) are not available early in the design. 
Over 400 were on order several months before the first XP-61 makes it's first flight on May 26th 1942 (no, you can't make them available for Midway 

" thirteen YP-61s were delivered during August and September of 1943 "
"The YP-61s initially did not have any airborne interception radar fitted, but the SCR-520, a preproduction version of the SCR-720 which was to go into the production P-61A, was installed"

Quotes from Joe Baugher's web site. 

Proposals for skinny fuselage P-61s with all fixed guns from the start should tale these factors into account.


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## tomo pauk (May 31, 2019)

Shortround6 said:


> Untitled Document
> 
> There was a bit of NIH in that report. The .5 Vickers was just a scaled up .303 Vickers with just about all the advantages and disadvantages. The manual for the .303 Vickers is supposed to list 26 or 27 different "stoppages", many of which can be diagnosed by noting the exact position of the cocking handle and some of which can be cleared with a good thump to the gun and tug or push on the cocking handle, some cannot but are still quickly cleared by a knowledgeable gunner. The Vickers had a very good reputation for durability and rare parts breakage. But it's "reliability" and rate of fire were why the RAF replaced it with the Browning for wing mounted guns. Going back to the Vickers for wing mounted guns may not have worked well.
> The article you referenced uses the wrong ammo information for the .50 cal under test. The 710 grain bullet and 2900fps MV wouldn't exist until about 1940. The British wouldn't get such ammo until later.



I will not claim here that Vickers (H)MGs were the next best thing after sliced bread, however there was more than a decade worth of time for the British to perfect both the HMGs and their installations before the war starts.



> We seem to have a disconnect here. The Fw 190V1 Prototype according to one source (which could be wrong) used a 160sq ft wing and the BMW 139 engine that was 350lbs lighter than the BMW801 ? according to this source the entire structure had to be stressed and strengthened. Normal loaded weight without armament had grown 25% to 7,550lbs (?) and wing loading had grown to 46.6lbs/sq/ft. A new wing of 196.98 sq ft was designed.



This is partly the point why I've suggested a DB engine to be installed - originally, the heavy BMW 139 (850 kg 'naked') was supplanted by an even heavier 801 (935 naked, 1155 kg outfitted), indeed necessitating strengthening of airframe, as well as a new, bigger & heavier wing (18.3 sq m instead of 14.9). The DB 601A was at 610 kg 'naked' (720 kg outfitted); add ~150 kg worth of cooling system and we're at 760 kg - 90 kg less than BMW 139. No fancy and heavy oil system, a lighter prop.
The DB 601E went to 660 kg 'naked' (725 outfitted), that will be ~810 with cooling system, or almost 80 kg lighter than a naked 801C or D. No armored oil system either, a lighter prop. Engines' weights, ready to be installed, are 1155 kg for the BMW 801C/D vs. ~875 for the DB 601E.
Other reasons for the DB engine is actual availability, lower drag, a far better reliability and lower consumption.

The Fw 190V1 went to 3000 kg ready for take off, the armed V2 to 3150 kg.



PAT303 said:


> The MkIII was redesigned using all the lessons learnt from the BOB, as Wuzak posted, the MkIII if built would have been the stand out fighter from 1940 onwards, it would also mean the MkVIII would be the main version instead of the interim Mk IX, in doing so fixing the single biggest downside to the spit, lack of internal fuel.



Spitfire Mk.III was not a whole redesign, but more of an ironed-out standard Spitfire - old wing, old fuselage, old tail, with aerodynamical nip & tuck there and there.


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## Shortround6 (May 31, 2019)

tomo pauk said:


> I will not claim here that Vickers (H)MGs were the next best thing after sliced bread, however there was more than a decade worth of time for the British to perfect both the HMGs and their installations before the war starts.



The British would have been better off just licencing the Big Browning and scaling it down to the .5 in Vickers cartridge size. They had given up on getting the .303 Vickers to work in remote fixed locations, why would they take on the headache of getting the big Vickers to work in similar circumstances? Penitential for a higher rate of fire favors the Browning. 





> This is partly the point why I've suggested a DB engine to be installed - originally, the heavy BMW 139 (850 kg 'naked') was supplanted by an even heavier 801 (935 naked, 1155 kg outfitted), indeed necessitating strengthening of airframe, as well as a new, bigger & heavier wing (18.3 sq m instead of 14.9). The DB 601A was at 610 kg 'naked' (720 kg outfitted); add ~150 kg worth of cooling system and we're at 760 kg - 90 kg less than BMW 139. No fancy and heavy oil system, a lighter prop.
> The DB 601E went to 660 kg 'naked' (725 outfitted), that will be ~810 with cooling system, or almost 80 kg lighter than a naked 801C or D. No armored oil system either, a lighter prop.
> Other reasons for the DB engine is actual availability, lower drag, a far better reliability and lower consumption.
> 
> The Fw 190V1 went to 3000 kg ready for take off, the armed V2 to 3150 kg.



The availability is subject to question, depending on year (or month) with demands for DB 601s coming from all sides. 
Prototype FW 190s had two Mg 17s which hardly worthwhile armament in 1939/40, granted with the DB you could try to put a gun through the prop. 

When you are done what advantage to you have over the 109 except for wider track landing gear? You have a higher staling speed unless you enlarge the wing. 
The small wing, light weight 190 is too small to take the DB 603 0r Jumo 213 engines when they show up without doing a major redesign.


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## tomo pauk (May 31, 2019)

Shortround6 said:


> The availability is subject to question, depending on year (or month) with demands for DB 601s coming from all sides.
> Prototype FW 190s had two Mg 17s which hardly worthwhile armament in 1939/40, granted with the DB you could try to put a gun through the prop.



I'd go with 3 cannons.
Availability of BMW 139 is about 5? The production of DB 601 can be ramped up much better than it will be the case with a brand new BMW 801.



> When you are done what advantage to you have over the 109 except for wider track landing gear? You have a higher staling speed unless you enlarge the wing.
> The small wing, light weight 190 is too small to take the DB 603 0r Jumo 213 engines when they show up without doing a major redesign.



World-beating rate of roll instead of questionable rate of roll of the 109, a far better cockpit layout than 109, 525 liters of internal fuel (550 L in unprotected tanks of the 190 prototype) vs. 400, can carry better firepower in the wings, wings being of a lower drag than what Bf 109 used, fully covered undercarriage for lower drag. 
The DB 603 will indeed need a bigger wing, among other things, althugh I'm not against the bigger wing entering production even some time in 1942 for DB 605-engined machine.


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## Ivan1GFP (May 31, 2019)

tomo pauk said:


> I'd go with 3 cannons.
> Availability of BMW 139 is about 5? The production of DB 601 can be ramped up much better than it will be the case with a brand new BMW 801.
> 
> World-beating rate of roll instead of questionable rate of roll of the 109, a far better cockpit layout than 109, 525 liters of internal fuel (550 L in unprotected tanks of the 190 prototype) vs. 400, can carry better firepower in the wings, wings being of a lower drag than what Bf 109 used, fully covered undercarriage for lower drag.
> The DB 603 will indeed need a bigger wing, among other things, althugh I'm not against the bigger wing entering production even some time in 1942 for DB 605-engined machine.



Hello Tomo Pauk,
My belief is that if the FW 190 had been switched to the DB 601 engine very early in the game, it would have gone pretty much nowhere.
The Me 109 was a "reasonably" streamlined aircraft with recessed radiators mounted in the wings.
Historically, the FW 190 with inline engines also had the annular radiator setup and drag would not have been different from what was achieved with the BMW 801 with a cooling fan.
Remote mount radiators such as in the wings would call for a serious redesign and possible alteration of armament possibilities.
The power achievable with a DB 601 engine at the time was significantly below what was achievable with the BMW 801.
The weight savings in power plant is offset by the significantly heavier structure of the FW 190.

My belief is that the result would be an aircraft that is no faster than the Me 109 and climbs slower but has a better roll rate and taps into the same limited source of engines as other aircraft demanded at the time. With a lower power to weight ratio, maneuverability would suffer as well.

- Ivan.

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## Kevin J (May 31, 2019)

tomo pauk said:


> I will not claim here that Vickers (H)MGs were the next best thing after sliced bread, however there was more than a decade worth of time for the British to perfect both the HMGs and their installations before the war starts.
> 
> 
> 
> ...


Let me repeat myself, no changes to the production lines until the threat of invasion is over, which means the successful counter attack at Moscow by the Soviets which threw the Nazi's back 100 km.


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## tomo pauk (May 31, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> My belief is that if the FW 190 had been switched to the DB 601 engine very early in the game, it would have gone pretty much nowhere.
> The Me 109 was a "reasonably" streamlined aircraft with recessed radiators mounted in the wings.
> Historically, the FW 190 with inline engines also had the annular radiator setup and drag would not have been different from what was achieved with the BMW 801 with a cooling fan.
> ...



Let's compare power of a DB 601E with that of BMW 801C. 
For take-off, in second half of 1941, it is 1200 PS vs. 1560. At altitude, it is 1200 @ 4.9 km vs. 1380 at 4.6 km. All figures are without ram effect, the DB 601E have had a better ram air intake, so it will gain more % of power at high speeds and high altitudes. By late 1941/early 1942, the DB 601E will make 1350 HP for take off, 1320 HP at 4.8 km.
The 190D-9 gained a 10% drag reduction by switching to a big V12 engine with an annular radiator vs. 190A-8. 10% drag reduction might not sound much, but you will gain more speed that way than by increasing the engine power by 10%. We know that D-9 was faster than A-8 by 40+ km/h at 6-7 km altitude, despite engine power being greater by just single digits, %-wise.
As for the engine availability, Germany will have to make/procure tooling for all of it's engines, be it V12s or twin radials. Tooling required for BMW 801s will not just materialize from thin air, the 801 didn't even shared for example bore and stroke with any previous BMW or BRAMO engine to help out.



Kevin J said:


> Let me repeat myself, no changes to the production lines until the threat of invasion is over, which means the successful counter attack at Moscow by the Soviets which threw the Nazi's back 100 km.



There were plenty, plenty of changes to production lines in mid/late 1940, when Westland was making a switch from Whirlwind production to Spitfires. There were also changes in production lines at Bristol, when change was being made from Beaufort to Beaufighter. 
Aparently, not everyone was convinced that Germans will land with their rubber ducks willy-nilly.


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## Kevin J (May 31, 2019)

tomo pauk said:


> Let's compare power of a DB 601E with that of BMW 801C.
> For take-off, in second half of 1941, it is 1200 PS vs. 1560. At altitude, it is 1200 @ 4.9 km vs. 1380 at 4.6 km. All figures are without ram effect, the DB 601E have had a better ram air intake, so it will gain more % of power at high speeds and high altitudes. By late 1941/early 1942, the DB 601E will make 1350 HP for take off, 1320 HP at 4.8 km.
> The 190D-9 gained a 10% drag reduction by switching to a big V12 engine with an annular radiator vs. 190A-8. 10% drag reduction might not sound much, but you will gain more speed that way than by increasing the engine power by 10%. We know that D-9 was faster than A-8 by 40+ km/h at 6-7 km altitude, despite engine power being greater by just single digits, %-wise.
> As for the engine availability, Germany will have to make/procure tooling for all of it's engines, be it V12s or twin radials. Tooling required for BMW 801s will not just materialize from thin air, the 801 didn't even shared for example bore and stroke with any previous BMW or BRAMO engine to help out.
> ...



With all respects you're wrong with the Whirlwind being replaced by the Spitfire in 1940, that happened in late 1941 when Westland made 50 Spitfire I's while everyone else had gone onto the Vb. Beaufort to Beaufighter, no problem, yes in 1940, both use the same wings, different engines, different fuselages. Its not a complete redesign.
British Production of Aircraft By Year During The Second World War


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## tomo pauk (May 31, 2019)

Kevin J said:


> With all respects you're wrong with the Whirlwind being replaced by the Spitfire in 1940, that happened in late 1941 when Westland made 50 Spitfire I's while everyone else had gone onto the Vb.



Indeed, you're right, Westland didn't make any Spitfires in 1940. On the other hand, they made their 1st Spitfires much before Soviets have thrown Germans 100 km from Moscow.



> Beaufort to Beaufighter, no problem, yes in 1940, both use the same wings, different engines, different fuselages. Its not a complete redesign.
> British Production of Aircraft By Year During The Second World War



Spifire III vs Spitfire I/II: same wing, same fuselage, much less of a difference in engine weight and size than it was between Taurus and Hercules.
A production Beaufighter was more of a brand new aircraft, than a redesign of the Beaufort.


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## Kevin J (May 31, 2019)

tomo pauk said:


> Indeed, you're right, Westland didn't make any Spitfires in 1940. On the other hand, they made their 1st Spitfires much before Soviets have thrown Germans 100 km from Moscow.
> 
> 
> 
> ...



From Wkipedia,
Supermarine Spitfire (early Merlin-powered variants) - Wikipedia 
The Mk III was the first attempt to improve the basic Spitfire design and introduced several features which were used on later marks. Powered by a Rolls-Royce RM 2SM, later known as the Merlin XX, developing 1,390 hp (1,036 kW) due to its two-speed supercharger, the wingspan was reduced to 30 ft 6 in (9.3 m) and the area reduced to 220 square feet (20.4 sq m) while the overall length was increased to 30 ft 4 in (9.2 m). The strengthened main undercarriage was raked forward two inches, increasing ground stability and had flaps to fully enclose the wheels when retracted. The tailwheel was also made fully retractable. The windscreen was redesigned, with a built-in, internal laminated glass, bulletproof panel and optically flat, laminated glass quarter panels.[73]

The first Mk III _N3297_ was first flown on 16 March 1940. In addition to _N3297_ in early 1941 a Spitfire Mk V, _W3237_ was converted to a Mk III, although it didn't have the retractable tailwheel. _W3237_ replaced _N3297_ when the latter was delivered to Rolls-Royce; _W3237_ went on to become a test aircraft and was still being used in September 1944.[74]

Although the new Spitfire was developed to replace the earlier marks on the production lines, a decision to allocate the limited supplies of Merlin XX to the Hurricane II series meant that the Mark III lapsed. Priority then focused on the Mark V series. The Mk III with the Merlin XX was capable of a maximum speed of 400 mph (640 km/h) at 21,000 ft (6,400 m).[75]

_N3297_ became the power-plant development airframe, the wings were replaced with standard Type A and the aircraft was delivered to Rolls-Royce at Hucknall. A prototype Merlin 60 two-stage engine was subsequently installed, in effect making this aircraft (renumbered the *type 348*) the prototype Mk IX.[76]

I'd wouldn't call these changes minor. Castle Bromwich was having difficulties getting the Spitfire IIa into production and you want to introduce a new mark, the III. You don't care that the Hurricane will be less effective without the Merlin XX engine. You cannot be serious. Maybe in peacetime, with limited production nos, no problem, with war, the threat of imminent invasion. Once the USSR was invaded it gives us a window of opportunity to change the production lines, the German defeat at Moscow, even better, the threat of invasion is off.


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## tomo pauk (May 31, 2019)

Kevin J said:


> From Wkipedia,
> Supermarine Spitfire (early Merlin-powered variants) - Wikipedia
> The Mk III was the first attempt to improve the basic Spitfire design and introduced several features which were used on later marks. Powered by a Rolls-Royce RM 2SM, later known as the Merlin XX, developing 1,390 hp (1,036 kW) due to its two-speed supercharger, the wingspan was reduced to 30 ft 6 in (9.3 m) and the area reduced to 220 square feet (20.4 sq m) while the overall length was increased to 30 ft 4 in (9.2 m). The strengthened main undercarriage was raked forward two inches, increasing ground stability and had flaps to fully enclose the wheels when retracted. The tailwheel was also made fully retractable. The windscreen was redesigned, with a built-in, internal laminated glass, bulletproof panel and optically flat, laminated glass quarter panels.[73]
> 
> ...



I would call the changes minor.
Wing was not some new design, just the standard wing with standard wing tip replaced by short wing tip - just like it was done on numerous Mk.Vs, IXs and VIIIs for example. (Dowding disliked the wing on the Mk.III 1st prototype, saying that it will be confused with Bf 109E in air combat).
Length grew due to installation of a longer engine, as we can expect.
Spitfire III with Merlin 60 has no bearings on 1940, not even on 1941.
I do care about Hurricane. Install a proper carb ( not the lousy float-type) on it, less draggy exhausts, Merlin XII and it is no worse than the historical Hurricane II. Later, install the Merlin 45.


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## Kevin J (May 31, 2019)

tomo pauk said:


> I would call the changes minor.
> Wing was not some new design, just the standard wing with standard wing tip replaced by short wing tip - just like it was done on numerous Mk.Vs, IXs and VIIIs for example. (Dowding disliked the wing on the Mk.III 1st prototype, saying that it will be confused with Bf 109E in air combat).
> Length grew due to installation of a longer engine, as we can expect.
> Spitfire III with Merlin 60 has no bearings on 1940, not even on 1941.
> I do care about Hurricane. Install a proper carb ( not the lousy float-type) on it, less draggy exhausts, Merlin XII and it is no worse than the historical Hurricane II. Later, install the Merlin 45.


The people who were fighting the war thought otherwise.


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## tomo pauk (May 31, 2019)

Kevin J said:


> The people who were fighting the war thought otherwise.



Have all of them though the same?


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## Kevin J (May 31, 2019)

tomo pauk said:


> Have all of them though the same?


In 1939, the Air Ministry considered cancelling Spitfire production in favour of the Beaufighter, in 1940, Castle Bromwich was way behind in ramping up Spitfire production. A Spitfire III in 1940 just isn't going to be approved.


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## tomo pauk (May 31, 2019)

Kevin J said:


> In 1939, the Air Ministry considered cancelling Spitfire production in favour of the Beaufighter, in 1940, Castle Bromwich was way behind in ramping up Spitfire production. A Spitfire III in 1940 just isn't going to be approved.



Indeed.
Let's make war-winning aircraft, like Defiant, Botha and Lysander by hundreds. In 1940.

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## Kevin J (May 31, 2019)

tomo pauk said:


> Indeed.
> Let's make war-winning aircraft, like Defiant, Botha and Lysander by hundreds. In 1940.


In the case of the Defiant, it became an effective night fighter. The Botha was a disaster. The Lysander could still have been useful in the event of an invasion, and used like the Po-2 in the USSR as a light night bomber. By the time the Spitfire III comes along, we're struggling to get Spitfire II production up and running. We need to keep the Hurricane competitive. The Hurricane is our most numerous front line fighter, its cheaper to build than the Spitfire, and while it is taking heavier losses, in terms of cost, it is still competitive in unit costs to the Spitfire. So if the Spitfire destroys 1.7 enemy per loss and the Hurricane only 1.1, but the Hurricane is 2/3 the Spitfire's unit cost and is easier to train to use and more rugged and usable overseas then it is the better fighter so it deserves the better engine.


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## fastmongrel (May 31, 2019)

Avro Lancaster fitted with 2 stage Merlins,120 ft wings, stripped of all armament and given a low drag gloss paint job. Dont fight the Nightfighters fly over them.

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## mikemike (May 31, 2019)

The Fw190 engine question is one of my favorite "What-ifs". Development of the DB603 began in mid-1936; the RLM stopped the DB603 cold in march 1937 (the official reason was "In this power class, we already have the BMW801 in development, and that is sufficient for our foreseeable needs"), otherwise it would have been in series production by the start of the war. The 190 was held back by problems with the engine and its installation; had the BMW actually worked from the start, the 190 would have gone into service late in 1940 or early in 1941 (intended initial armament, b.t.w., was 2xMg151 and 2xMG17 in the wing roots). Focke-Wulf put the DB603 into the 190 early in 1942. The installation posed no particular problems, the rear fuselage had to be lengthened slightly to compensate for the longer nose, and the DB603 power pack with annular radiator weighed actually less than the BMW801 installation. In mid-1942, the Fw190 V15, with a pre-series engine, demonstrated a maximum speed of 696km/h (434 mph) at an altitude of 6950 m (22.790 ft) using climb power, and the V16 achieved 724 km/h at 9000 m (451 mph at 29.500 ft) and a climb rate of 17.5 m/sec (3440 fpm) up to 4500 m (14.750 ft) using takeoff/emergency power, all this with the series-production wings. Putting this all together, had the development of the DB603 progressed normally, the Fw190 series could have switched early to something very close to the Ta152 with an engine reliably delivering about 1600 - 1650 hp, giving the Luftwaffe a fighter with a performance surpassing that of the Spit IX in the early summer of 1941.

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## Shortround6 (May 31, 2019)

Kevin J said:


> In the case of the Defiant, it became an effective night fighter. The Botha was a disaster. The Lysander could still have been useful in the event of an invasion



The effective night fighter is quite debatable, a fair number were used as night fighters and few German planes were shot down by them But over the winter of 1940/41 none of the British night fighters were shooting down German aircraft in more than 1s and 2s. The Defiant didn't get radar until the fall of 1941, successful interceptions by Defiants at night in the fall/winter of 1941/42 can be counted on the fingers of one had with fingers left over. The Lysander was pretty much useless for any combat role. Using a 900hp engine to do what the PO-2 did with 125 hp rather points out the waste of resources the Lysander was. 




Kevin J said:


> So if the Spitfire destroys 1.7 enemy per loss and the Hurricane only 1.1, but the Hurricane is 2/3 the Spitfire's unit cost and is easier to train to use and more rugged and usable overseas then it is the better fighter so it deserves the better engine.



No, they figured the Spitfire could get by using the Merlin XII engine against the 109E (they didn't know about the F). The Hurricane didn't _deserve_ the MK XX engine because it was better.
It got the MK XX engine because it was the Best way to keep the Hurricane competitive. Any other version of the Merlin available in the Fall of 1940 would have meant a Hurricane of such poor performance that it would never operate at close to parity with the 109. Using the MK XII in the Spit and the MK XX in the Hurricane got the largest number of roughly equal fighters. 
MK XX Spits would have been better but MK III & MK XII Hurricanes would have been distinctly 2nd rate.

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## Ivan1GFP (May 31, 2019)

tomo pauk said:


> Let's compare power of a DB 601E with that of BMW 801C.
> For take-off, in second half of 1941, it is 1200 PS vs. 1560. At altitude, it is 1200 @ 4.9 km vs. 1380 at 4.6 km. All figures are without ram effect, the DB 601E have had a better ram air intake, so it will gain more % of power at high speeds and high altitudes. By late 1941/early 1942, the DB 601E will make 1350 HP for take off, 1320 HP at 4.8 km.



Hello Tomo Pauk,
By 1942, the BMW 801D would have been in production and that would be giving about 1700 PS at Take Off.
Power at altitude would also be improved and that isn't even counting the power adders used for emergency power.



tomo pauk said:


> The 190D-9 gained a 10% drag reduction by switching to a big V12 engine with an annular radiator vs. 190A-8. 10% drag reduction might not sound much, but you will gain more speed that way than by increasing the engine power by 10%. We know that D-9 was faster than A-8 by 40+ km/h at 6-7 km altitude, despite engine power being greater by just single digits, %-wise.



I have always thought that the A-9 was a closer match than the A-8 to the Dora and the margin for speed may be just a bit closer.
Certainly the armament installation of the A-9 is closer.
The FW 190D-9 was also the end result of a LOT of development and I am not entirely convinced that such a clean installation was likely in 1941 especially when one looks at the other FW 190 prototypes with inline engines.



tomo pauk said:


> As for the engine availability, Germany will have to make/procure tooling for all of it's engines, be it V12s or twin radials. Tooling required for BMW 801s will not just materialize from thin air, the 801 didn't even shared for example bore and stroke with any previous BMW or BRAMO engine to help out.



I believe the issue here is that the BMW 801 would be relying on different factories, different engineering staff, etc.
If it were so simple to just tool up another factory to build the same Daimler Benz engine, then it would have made more sense to have everyone build those instead of the early JuMo engines or BMW 801 engines that were being installed in bombers.

- Ivan.


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## PAT303 (May 31, 2019)

Spifire Mk.III was not a whole redesign, but more of an ironed-out standard Spitfire - old wing, old fuselage, old tail, with aerodynamical nip & tuck there and there.[/QUOTE]

Totally different engine, different cropped wings with undercarriage doors, retractable tail wheel, internal BP wind screen, new 7'' longer fuselage to improve the COG. All up the MkIII rolled better, accelerated better was 60MPH faster than the Emil, both at best altitude. It's a shame it wasn't produced but war time conditions dictated terms

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## wuzak (May 31, 2019)

PAT303 said:


> Totally different engine, different cropped wings with undercarriage doors, retractable tail wheel, internal BP wind screen, new 7'' longer fuselage to improve the COG. All up the MkIII rolled better, accelerated better was 60MPH faster than the Emil, both at best altitude. It's a shame it wasn't produced but war time conditions dictated terms



The wings were modified, not standard. The wing tips were cropped, but it wasn't the removable tips of the standard wing.

The fuselage was also strengthened, and the radiator size increased and the duct redesigned to lower drag.

And the Mk III was maybe 50mph faster than the Bf 109E.


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## wuzak (May 31, 2019)

Kevin J said:


> In the case of the Defiant, it became an effective night fighter. The Botha was a disaster. The Lysander could still have been useful in the event of an invasion, and used like the Po-2 in the USSR as a light night bomber. By the time the Spitfire III comes along, we're struggling to get Spitfire II production up and running. We need to keep the Hurricane competitive. The Hurricane is our most numerous front line fighter, its cheaper to build than the Spitfire, and while it is taking heavier losses, in terms of cost, it is still competitive in unit costs to the Spitfire. So if the Spitfire destroys 1.7 enemy per loss and the Hurricane only 1.1, but the Hurricane is 2/3 the Spitfire's unit cost and is easier to train to use and more rugged and usable overseas then it is the better fighter so it deserves the better engine.



Aircraft can be replace, pilots are more difficult, especially experience pilots.

Losing 50% greater numbers of Hurricanes than Spitfires may be more cost effective, but when you include the value of the pilot, maybe not so much.

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## Kevin J (May 31, 2019)

Shortround6 said:


> The effective night fighter is quite debatable, a fair number were used as night fighters and few German planes were shot down by them But over the winter of 1940/41 none of the British night fighters were shooting down German aircraft in more than 1s and 2s. The Defiant didn't get radar until the fall of 1941, successful interceptions by Defiants at night in the fall/winter of 1941/42 can be counted on the fingers of one had with fingers left over. The Lysander was pretty much useless for any combat role. Using a 900hp engine to do what the PO-2 did with 125 hp rather points out the waste of resources the Lysander was.
> 
> 
> 
> ...



If the Germans had invaded in 1940/41 then cost effective or not, regardless of type, we would have thrown everything against them even Mohawks. In the 1940/41 Blitz, the Defiant NF I with two pairs of Mk 1 eyeballs was always going to be more effective than the Hurricane which was our primary night fighter but only had 1 pair of Mk 1 eyeballs.


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## wuzak (May 31, 2019)

Kevin J said:


> In 1939, the Air Ministry considered cancelling Spitfire production in favour of the Beaufighter, in 1940, Castle Bromwich was way behind in ramping up Spitfire production. A Spitfire III in 1940 just isn't going to be approved.



Not so much cancelling production as not ordering more.

The plan was to replace them with the Typhoon/Tornado, not Beaufighters and Hurricanes.

btw, Supermarine's time getting the Spitfire into production was one of the reasons that the Type 324 (twin Merlin, 12 0.303" mg) lost out to the Tornado/Typhoon (Sabre, 12 x 0.303" mg).

Supermarine also proposed the Type 327, a development of the Type 324 proposal, for the cannon armed fighter program which led to the Beaufighter.


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## wuzak (May 31, 2019)

Kevin J said:


> In 1939, the Air Ministry considered cancelling Spitfire production in favour of the Beaufighter, in 1940, Castle Bromwich was way behind in ramping up Spitfire production. A Spitfire III in 1940 just isn't going to be approved.



In fact, the Spitfire III was approved for production. A letter to Supermarine in October 1940 approved the production of an additional 1,000 Spitfires, in addition to the previous order of 1,500, to be built at the Castle Bromwich factory. The additional 1,000 Spitfires were to be the MK.III type with the Merlin XX and 8 x 0.303" mgs.


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## Shortround6 (May 31, 2019)

Kevin J said:


> If the Germans had invaded in 1940/41 then cost effective or not, regardless of type, we would have thrown everything against them even Mohawks. In the 1940/41 Blitz, the Defiant NF I with two pairs of Mk 1 eyeballs was always going to be more effective than the Hurricane which was our primary night fighter but only had 1 pair of Mk 1 eyeballs.


 During the night Blitz of 1940/41 British night fighters, including Blenheims with radar and a few Beaufighters shot down a grand total of *8 *german aircraft in the first two months. The next 3 months were even worse, one month may have seen no German aircraft shot down by night fighters, In March things got better with 22 shot down, mostly by Beaufighters with MK IV radar. April saw the total of claims rise to 48 and in the first two weeks of May the night fighters made 96 claims. By this time there were nearly 200 Beaufighters, most with MK IV radar. 
Nights were also getting shorter which helped the non radar equipped planes. 

Now the Defiant _might _have been the most successful in those first two months but shooting under 8 planes (the other aircraft got a few) out of 12,000 german sorties is hardly successful in normal terms, the numbers of German planes shot down until March/April are statistically meaningless. 

BTW, the Mohawks may not have been as bad as you think. They were the best fighter the French had in April/May of 1940. 

throwing everything you have at an enemy sometimes accomplishes nothing except showing that your pilots can die bravely. Something like 70 Lysanders were shot down over France and accomplished next to nothing. Fighting smarter is a better answer. Properly coordinated attacks with proper escort instead of penny packet (or half penny) attacks without escort and using ill suited aircraft/weapons.


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## Zipper730 (May 31, 2019)

Regarding the B-26 ideas



Greg Boeser said:


> Go with the longer wing right from the start.


Didn't that take away high speed handling characteristcs?


> Fowler flaps.


Would have improved low-speed handling quite a bit, I'm curious why they didn't field those...


> *Redesign the bomb bay doors to eliminate drag. (Folding doors caused massive drag when open, reducing top speed by 25 mph.) Roll up doors like on B-24 were suggested, but never implemented.


Why didn't they proceed the rolladoors/roll-up doors?


> Redesign bomb bay with capacity for tandem racks, thus eliminating need for second bomb bay.


Generally I follow the RAF's rules on this: Never use two small bays when one huge one will do the job.


> Move turret forward to improve CG.


What happened with the turret in then current position? Was the airplane excessively twitchy?


> Add RADAR


When did H2S & H2X become first available for night-bombing operations?



tomo pauk said:


> B-26 with fuselage tailored around a bomb bay and crew of 5


What do you mean, tailored around a bomb-bay? Why 5 crew members, wouldn't that get rid of at least one gunner?

I'm also curious if they should have pursued the twin-stage supercharger set-up. I figure the engine was in prototype stage during the development of the XF4U and was flying as of May. The plane would fly in November, so it seems like it would work if one stepped up production.


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## Zipper730 (May 31, 2019)

Shortround6 said:


> Now, does that mean guns that didn't exist (but could be made with existing technology?)


I suppose if the technology meant it could have realistically been doable with what existed, I suppose you could take it there if you wanted to.

I'm curious why the USAAC seemed to produce such heavy cannon designs (I'm not talking about bore, I'm talking about the mass of the cannon -- the HS.404 was positively light compared to some of the designs).


> In the Mid 30s the US still had the low velocity ammo.


I'm curious why the velocity was lower and what velocities are you talking about?


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## Shortround6 (May 31, 2019)

Fowler flaps


Zipper730 said:


> Would have improved low-speed handling quite a bit, I'm curious why they didn't field those...



They have to be designed in from the start. They cannot be added at a later date without just about a total redesign of the wing. They may require a different rear spar location (or major attachment point) that more standard flaps. 



Zipper730 said:


> I'm also curious if they should have pursued the twin-stage supercharger set-up. I figure the engine was in prototype stage during the development of the XF4U and was flying as of May. The plane would fly in November, so it seems like it would work if one stepped up production.



Both North American and Martin had designs and were building prototypes for high altitude bombers. trying to turn the B-25 or B-26 or even the A-20 into a high altitude plane was a duplication of effort and was going to delay service introduction. 

Two prototypes were ordered on February 13, 1940 





NA XB-28

martin XB-27 with turbo charged R-2800s




some design work done but no metal cut. 

The Army was finding out that flying bombers at high altitude wasn't quite as easy as they thought. They needed better oxygen systems and better heated flying suits at the very least and pressure cabins and remote control gun mounts to prevent altitude sickness and frostbite. The planes could survive better than the crews. it took a while longer to figure out that bombing form altitudes higher than the B-17 and B-24 bombed at really hurt accuracy (and that is saying something)


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## Shortround6 (May 31, 2019)

Zipper730 said:


> I'm curious why the velocity was lower and what velocities are you talking about?



Until about 1940 the US .50 cal ammo used a 753 grain bullet at about 2500fps velocity. The .50 cal was designed at the end of WW I. Smokeless powder was about 40 years old. By the late 30s you had another 20 years of R&D on smokeless powder and they found that a new powder could offer significantly higher velocity at the same peak pressure. They also lightened the bullet up slightly. This ammo was about 20% less powerful than the M2 ball or AP that was used for most of WW II by the Americans. The British in the early part of the war used ammo manufactured to the old specifications, whether US "surplus" (this was cash and carry, not lend lease) or contracts with american companies like Remington.


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## Zipper730 (May 31, 2019)

Shortround6 said:


> Fowler flaps . . . . They have to be designed in from the start.


Of course.

As for altitude capability, why did they design a high altitude and low altitude design?


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## Greg Boeser (May 31, 2019)

Zipper730,
The short, symmetrical wing was chosen because that met the Army's requirements for high speed, but at the cost of higher stall speeds, longer take offs. The B-25 used a more conventional airfoil and though it cost speed, it improved low speed handling, improved take off performance.
In a way the B-26 tried to meet as many expectations of the Army's requirement as physically possible, using the technology available at that time, but sacrificed much to achieve it.
The A-26, which began design just a year later, exceeded the B-26 in virtually every category. But it was designed under a different set of requirements.
The existence of the A-26 is the reason that many proposed improvements were not made to the B-26. The Army froze development on the B-26 and cancelled contracts as the A-26 neared gestation. The B-26 was costly to build, and the A-26 promised to be an improvement at a similar cost, so why invest more $$$ into an obsolescent design? The B-25 continued in production because it was cheaper and a tamer handler.

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## Kevin J (Jun 1, 2019)

Shortround6 said:


> During the night Blitz of 1940/41 British night fighters, including Blenheims with radar and a few Beaufighters shot down a grand total of *8 *german aircraft in the first two months. The next 3 months were even worse, one month may have seen no German aircraft shot down by night fighters, In March things got better with 22 shot down, mostly by Beaufighters with MK IV radar. April saw the total of claims rise to 48 and in the first two weeks of May the night fighters made 96 claims. By this time there were nearly 200 Beaufighters, most with MK IV radar.
> Nights were also getting shorter which helped the non radar equipped planes.
> 
> Now the Defiant _might _have been the most successful in those first two months but shooting under 8 planes (the other aircraft got a few) out of 12,000 german sorties is hardly successful in normal terms, the numbers of German planes shot down until March/April are statistically meaningless.
> ...



You're making some serious assumptions here about an ideal World where people act rationally. Anyway, in 1941 during the air war over France, 'leaning into France', all the RAF achieved was the unnecessary death of its airmen for propaganda purposes to show that they were doing something. If only we could have had those Spitfire Vb's in places like Malta, Singapore and Ceylon. That would have been much more useful. Perhaps no city bombing until area bombing was introduced in 1942 then we could have had better Maritime Recce planes for Coastal Command.


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## PAT303 (Jun 1, 2019)

Leaning into France was a poorly executed plan that was in my opinion a reversed BOB with Germany having the advantage. Saying that if the RAF had MkIII Spits instead of MkV's they could have given JG 26 in particular a very bloody nose. The MkV was available when needed and played an important part in the war but it was just the equal of the 109F and outclassed by the 190A, the MkIII if it could have been made could of taken on both, but it's all history now.


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## Kevin J (Jun 1, 2019)

Just read a document about projected RAF aircraft for 1935 to 1950. The only viable looking long range army co-operation single-seat fighter was the Boulton Paul P.94 IIRC. Four cannon, four m/c guns and about 164 imp gal with 2 x 30 imp gal aux tanks. Top speed 360 mph with Merlin XX, but that's inferior to the NA Mustang with V-1710-39.


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## wuzak (Jun 1, 2019)

Zipper730 said:


> When did H2S & H2X become first available for night-bombing operations?



1943.


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## fliger747 (Jun 1, 2019)

Of course the point of the thread is what-if's. Many good-great ideas were come up with during the war, but filtering out which ones were going to work was sometimes problematical and often in error. The multiple path of development was the not all eggs in one basket approach. Hellcat was an example. Some planes that had fabulous potential such as the P47-J (505 mph) simply were going to be too much of a production re arrangement in a situation where we needed good planes today and not a better one tomorrow.

This was true in many weapon systems. Perhaps the M4 Sherman was an example of a compromise between the Russian and German approaches, things like transportability, field mobility etc. Better to have a tank that is there than one that is not.

Development took time, the R2800 C models were a big improvement over the B models and made some of the high HP late war fighters possible. But really a very different engine in the details, the devil's home.

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## Shortround6 (Jun 1, 2019)

This is "supposed" to be the Bolton Paul P.94 prototype or the plane they based the performance estimates on. 





But a lot of things do not line up. The quoted armement, fuel, performance and so on are going to need divine intervention of a biblical nature to achieve, parting of clouds, rays of golden light and thunderous voices from on high. 
This aircraft in the pictures seems to have an early Merlin, the later Merlin XX having a bigger oil cooler.




Somehow removing the turret and about 600lbs is supposed to allow the installation of about 500lb worth of cannon, 90-100lbs worth of machine guns, plus ammo, plus over 50IMP gallons of internal fuel (375lbs plus weight of the tanks) and yet the resulting plane is supposed to fly over 40mph faster than the MK II Defiant with the same engine. 
one suggestion was for the cannon (and maybe all the guns) to tilt up to 17 degrees fro ground strafing. I wonder how much that weighed and what the drag was of those 20mm gun barrels tilted 17 degrees from the line of flight. 

There are "what ifs" and there are fantasy aircraft even if the fantasy has an official designation.

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## tomo pauk (Jun 1, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> By 1942, the BMW 801D would have been in production and that would be giving about 1700 PS at Take Off.
> Power at altitude would also be improved and that isn't even counting the power adders used for emergency power.



By Spring of 1942 indeed the BMW 801D is around. However, it was de-rated until mid-October 1942. De-rating meant reduction of rpm and boost - for example, 'Notleistung' was reduced from 2700 rpm and 1.42 ata down to 2450 rpm and 1.35 ata. What it represented for the pilot is a reduction from possible 1440 PS at 5.7 km down to ~1350 PS at ~5.4 km. We still have heavy powerplant, that uses C3 fuel instead of B4, with drag and consumption greater than of the DB 601E/605A engine, while Notleistung is limited to 3 minutes, vs. 5 minutes for the DBs.
A de-rated DB 605A engine was being installed by mid-1942, 1250 PS at 5.7 km.
Power adders for BMW 801 were not a happy story, DB 605s were much better in that regard. Granted, the fully-rated BMW 801 will have 1700 PS for take off, but for the fighters the altitude power was a much more important thing. We know that P-40s and P-39s with 1600 HP at 2500 ft were nothing fancy above 15000 ft.



> I have always thought that the A-9 was a closer match than the A-8 to the Dora and the margin for speed may be just a bit closer.
> Certainly the armament installation of the A-9 is closer.
> The FW 190D-9 was also the end result of a LOT of development and I am not entirely convinced that such a clean installation was likely in 1941 especially when one looks at the other FW 190 prototypes with inline engines.



The Jumo 213A will need bigger raditors than DB 601 engines, due to making greater power. Bigger radiators are likely to make greater drag.
We can take a look at A-9, of course. At 5.7 km, BMW 801S was making 1650 PS, vs. Jumo 213A making ~1550 PS, yet A-9 was slower than D-9 by 20 km/h above 6.5 km.



> I believe the issue here is that the BMW 801 would be relying on different factories, different engineering staff, etc.
> If it were so simple to just tool up another factory to build the same Daimler Benz engine, then it would have made more sense to have everyone build those instead of the early JuMo engines or BMW 801 engines that were being installed in bombers.
> 
> - Ivan.



We can also make a speculation how interested was Germany in investing money in a private compaby that DB was, vs. in the government-owned Jumo in the time Germany beliveed that the've won the war? For whatever the reason, production of DB engines stayed about the same from late 1939 to late 1940, while production of Jumo engines doubled in the same time.
Note that I don't advocate cancelling the BMW 801s, they can come in handy on Ju-88s, a small Ju 288, and later, f/b versions of Fw 190. What I'd cancel is the Bf 110 and subsequent 210 programe by winter of 1940/41.


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## Shortround6 (Jun 1, 2019)

Trying to come up with a few ideas,

for the Germans, leave some sort of wing guns in the 109F even if it just a MG17 in each wing. this roughly doubles the firepower of the F-0 when the 55-60 rounds in the MG/FFM run out. Leaves an option for the 109G to have one 20mm and four MG 131s? Not B-17 killing armament but something better than hanging guns under the wing. 

AS mentioned before for the Ju-87, double the number of MG 17s, you can carry bombs and strafe(somewhat) without hanging gun pods on the under wing racks. 

Germans actual develop a full power turret with two MG 17s or MG 131s and stick it on top of the HE 111. And put up to date engines in the He 111 after 1940. 

The British could use a host of changes, some are simple, like deciding in 1936/37 that variable pitch/constant speed props are not the work of the devil and are to resisted at all costs 
Some are operational, you don't have to give up bombing Germany until 1942 in order to give Coastal Command 100-200 Blenheims in 1939/40. The MK IV Blenheinm was a designed as quick and dirty modification of the MK I Blenheim to suit a Canadian requirement for a maritime recon aircraft. It was originally called the Bolingbroke. Not as good as the Beaufort but it could have been available in numbers (half dozen squadrons anyway) when the Beaufort was still entering production. 

The Americans are in pretty good shape in regards to engines and propellers. Now just beat somebody over the head until they agree that sticking 800-1000lbs worth of guns and ammo in 1200hp airplanes isn't really a good idea 

more later.

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## Shortround6 (Jun 1, 2019)

tomo pauk said:


> We can also make a speculation how interested was Germany in investing money in a private company that DB was, vs. in the government-owned Jumo



DB seemed to be a bit late (chronically?) in delivering either the number of engines or engines that delivered the promised power. Maybe it was not their fault but the change over to DB 601s from Jumo 210s and DB 600s seems to have been later than desired.


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## Glider (Jun 1, 2019)

I know it sounds obvious but there have been a few postings about having more effective nightfighters earlier in the war. It doesn't matter what the performance of the aircraft, the key ingredient is the radar. The time and effort invested, and achievements made were remarkable. Developing what was a brand new technology to fit, work and be reliable in a small vibrating aircraft must have been the hardest task in the early years probably only matched by code breaking and couldn't have been achieved any quicker. The fact that the Beaufighter entered production at more or less the same time was a match made in heaven. 
With the mk IV radar the Beaufighter became the first true nightfighter with speed, range, firepower plus of course radar. It could not have been brought forward any earlier.

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## Shortround6 (Jun 1, 2019)

The Blenheims and their crews pioneered the way but the early radars just weren't good enough, or the Blenheim fast enough or heavily armed enough to show decisive results. 
They certainly showed the concept had possibilities. 

The British then threw away an opportunity when they failed to use some of the Early Douglas Bostons as true night fighters, with either 8 gun or 12 gun noses and their higher speed they would have covered two of the conditions of a better night fighter but if equipped with the older radar might not have showed significantly better results. Some were used as intruders (without radar?) over France during the Blitz to shoot down returning german bombers. 

British then used up a number of the Douglas aircraft (about 70) on the far from successful turbine light scheme. Most of these were equipped with the MK IV radar in the early days to no effective purpose, as the accompanying Hurricanes were never (or once?) able to turn a contact/illumination into a kill. 
Some sources do say that the First radar equipped Hovacs ( with MK IV radar) weren't issued to a squadron until late April of 1941 which is too late to have any significant impact on the Night Blitz. So yes the Beaufighter was by far the plane that truely introduced successful night fighting. 

The British may still have been suffering from a shortage of "Dixon" incendiary rounds during the night blitz reducing the effectiveness of the .303 batteries?


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## tomo pauk (Jun 1, 2019)

Shortround6 said:


> Trying to come up with a few ideas,
> 
> for the Germans, leave some sort of wing guns in the 109F even if it just a MG17 in each wing. this roughly doubles the firepower of the F-0 when the 55-60 rounds in the MG/FFM run out. Leaves an option for the 109G to have one 20mm and four MG 131s? Not B-17 killing armament but something better than hanging guns under the wing.



Bf 109F-0 was a rather rare bird? Granted, it could've used more firepower - 2 HMGs + MG FFMs, or just 3 MG FFMs each with a 90 rd drum (otherwise used 1st from late 1942?). A belt-fed MG FF(M) was no rocket science, after all, however it was developed even later than MG 151/20, and used probably only at Do 217 NFs.



> AS mentioned before for the Ju-87, double the number of MG 17s, you can carry bombs and strafe(somewhat) without hanging gun pods on the under wing racks.



How about a dedicated tank-buster version with 2x MK 101s for 1941/42?



> Germans actual develop a full power turret with two MG 17s or MG 131s and stick it on top of the HE 111. And put up to date engines in the He 111 after 1940.



Hopefully Germans can make a better bomber than it was the venerable He 111? But yes, the 111 will need improvement of defensive firepower.



> Some are operational, you don't have to give up bombing Germany until 1942 in order to give Coastal Command 100-200 Blenheims in 1939/40. The MK IV Blenheinm was a designed as quick and dirty modification of the MK I Blenheim to suit a Canadian requirement for a maritime recon aircraft. It was originally called the Bolingbroke. Not as good as the Beaufort but it could have been available in numbers (half dozen squadrons anyway) when the Beaufort was still entering production.



Bolingbroke was the Mk.V.
Mk.IV was about the furthest the basic Benheim design need to be pushed?



> The Americans are in pretty good shape in regards to engines and propellers. Now just beat somebody over the head until they agree that sticking 800-1000lbs worth of guns and ammo in 1200hp airplanes isn't really a good idea



They might also need some convincing in 1939-41 that drop tanks are not work of the devil.



Shortround6 said:


> DB seemed to be a bit late (chronically?) in delivering either the number of engines or engines that delivered the promised power. Maybe it was not their fault but the change over to DB 601s from Jumo 210s and DB 600s seems to have been later than desired.



Granted, the 601N was a not a paramount of reliability, the 601E was fully rated after 6-7 months, the 605A after more than a year (managing to kill Marseille in process), while 603A was trying to replicate problems of early BMW 801s and Sabres in 1943.


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## Kevin J (Jun 1, 2019)

IIRC Molders rigged up a Bf-109F-1 with two cannon in the wings, I've seen the photo somewhere. Don't know what the effect on performance was.


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## Zipper730 (Jun 1, 2019)

Shortround6 said:


> Both North American and Martin had designs and were building prototypes for high altitude bombers.


While this might be a redundant reply, it's basically aimed in response to information that I stumbled across: I don't know exactly when the XB-27 began design work, but the XB-28 was ordered after the B-26 began design.

A two-speed supercharger would theoretically give around 19000 - 21500 feet (based on the F4U-1 figures) without ram. If I recall, the design estimates called for the presumption of an ACA 2000'-3000 feet higher with ram. This would yield 21000-23500 feet on the low end and 22000-24500 feet on the upper end. The F4U-1 was generally able to do around 23800 feet ACA.


> Until about 1940 the US .50 cal ammo used a 753 grain bullet at about 2500fps velocity.


So we started using the faster rounds around 1940 and after?



Greg Boeser said:


> The short, symmetrical wing was chosen because that met the Army's requirements for high speed, but at the cost of higher stall speeds, longer take offs.


From what I remember the real problem with the B-26 was not so much high takeoff and landing speeds, but the controllability speed with one engine dead. From what I remember, it was pretty high, and without proper training, or bad luck (engine cuts out as you're low to the ground), you'll go out of control and crash.


> In a way the B-26 tried to meet as many expectations of the Army's requirement as physically possible, using the technology available at that time, but sacrificed much to achieve it.


I wonder why they didn't decide to use the fowler-flap design.


> The existence of the A-26 is the reason that many proposed improvements were not made to the B-26. The Army froze development on the B-26 and cancelled contracts as the A-26 neared gestation.


Are you sure about that, according to this, the design did't begin until the fall of 1940, at which point the B-26 was nearing its first flight, and the proposal wasn't formally proposed until January 1941.

That said, it was designed to replace the A-20 Havoc, the B-25 Mitchell, and B-26 Marauders (which is pretty amazing that you're basically designing a successor before the predecessor flew).

That said, imagine an A-26 with an R-2800 with a two-stage supercharger? 



wuzak said:


> 1943.


Okay, so radar additions would not have been available until then. I would assume you'd mount it behind the bomb-bay on the lower fuselage like how it was done on the Avro Lancaster?


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## Shortround6 (Jun 1, 2019)

tomo pauk said:


> Bf 109F-0 was a rather rare bird? Granted, it could've used more firepower - 2 HMGs + MG FFMs, or just 3 MG FFMs each with a 90 rd drum (otherwise used 1st from late 1942?). A belt-fed MG FF(M) was no rocket science, after all, however it was developed even later than MG 151/20, and used probably only at Do 217 NFs.


This kind of goes with using existing guns/technology or speeding up development of some guns or it could have been built?
When did the 90 round drums show up? and will they fit in a 109 wing? 
By the time the Japanese had belt fed Oerlikons the Germans were using the MG 151 making the point rather moot.
In any case even with the 15mm MG 151 a bit more firepower wouldn't hurt. ANd with the DB 601 engine situation the way if was (DB 601N engine good for 1175 hp at 4800 meters) it iis going to be a careful balance between firepower and performance. 



tomo pauk said:


> How about a dedicated tank-buster version with 2x MK 101s for 1941/42?


one source says they only built about 180. That could be solved (put back into production) but in 1942 the MK 101 is too light a gun. And it only fires about 50% faster than the 37mm gun. One or two more shots per barrel per attack? 
For attacking soft targets four MG 17s seems to be a decent change even if not spectacular. 



tomo pauk said:


> Hopefully Germans can make a better bomber than it was the venerable He 111? But yes, the 111 will need improvement of defensive firepower.


 I have a bit of a soft spot for the old He 111, it was supposed to be replaced several times but it never happened and in the meantime they kept using it with pretty much 1940 defensive guns and pretty much 1940/early 1941 engines. It didn't get an MG 131 in the dorsal position until 1942 (He 111H-11?) The power turret, which was power only in traverse(?) came later, a modification kit to the H-16. granted it was never going to fight it's way into a a target but better defence might have helped the loss rate. Same with the engines, a bit more speed or more speed and altitude when flying on one engine? 




tomo pauk said:


> Bolingbroke was the Mk.V.


The Bolingbroke name was re-used several times in the Blenheim history. You are correct in that in end the MK V was known as the Bolingbroke. earlier the name would come up and then be dropped as it was felt there either wasn't enough change in the aircraft and/or it would cause confusion. 



tomo pauk said:


> They might also need some convincing in 1939-41 that drop tanks are not work of the devil.


This one is really curious as most of the early 1930s fighter (biplanes) and attack planes carried drop tanks or jettisonable tanks. I have never heard of any problems but that seems a rather sort period of time to forget about them unless there were problems. 



tomo pauk said:


> Granted, the 601N was a not a paramount of reliability, the 601E was fully rated after 6-7 months, the 605A after more than a year (managing to kill Marseille in process), while 603A was trying to replicate problems of early BMW 801s and Sabres in 1943.



I am thinking even earlier when around 25% or more of the Bf 110s that attacked Poland used Jumo 210 engines and the large number of 109Ds that were built using Jumo 210s after the DB engines were used in air races in Switzerland. 
I don't know if DB was starved for funds or what was going on but even the He 111 went from using DB 601s on the P to Jumo 211s on the H (which actually came later)

If you do have an extra DB engines floating around perhaps a better use for them than a DB powered FW 190 would be more Do 215 bombers? It was a close to German Mosquito as you were going to get early in the war.


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## Ivan1GFP (Jun 1, 2019)

Greg Boeser said:


> Zipper730,
> The short, symmetrical wing was chosen because that met the Army's requirements for high speed, but at the cost of higher stall speeds, longer take offs. The B-25 used a more conventional airfoil and though it cost speed, it improved low speed handling, improved take off performance.
> In a way the B-26 tried to meet as many expectations of the Army's requirement as physically possible, using the technology available at that time, but sacrificed much to achieve it.



Hello Greg Boeser,
That WAS the explanation for the symmetrical airfoil, but the really interesting thing is that even with more power, the Marauder wasn't substantially faster than the Mitchell even in the early versions and in the war time versions, they were nearly identical in level speed.
I had always wondered why anyone would use a symmetrical airfoil in an aircraft that was not intended to spend any time flying inverted. Eventually I came across an article that quoted Peyton Magruder as stating that the symmetrical airfoil was probably a mistake.



Shortround6 said:


> The Americans are in pretty good shape in regards to engines and propellers. Now just beat somebody over the head until they agree that sticking 800-1000lbs worth of guns and ammo in 1200hp airplanes isn't really a good idea



Hello Shortround6,
This comment surprises me a bit.
The lack of development of a two stage or even a two speed supercharger seems like a serious mistake.
The theory was that Turbochargers would be used when needed for high altitude performance but that doesn't seem to have worked well with the smaller aircraft.



Kevin J said:


> IIRC Molders rigged up a Bf-109F-1 with two cannon in the wings, I've seen the photo somewhere. Don't know what the effect on performance was.



Hello Kevin J,
I believe those were Adolf Galland's aircraft.

- Ivan.

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## Ivan1GFP (Jun 1, 2019)

tomo pauk said:


> Power adders for BMW 801 were not a happy story, DB 605s were much better in that regard. Granted, the fully-rated BMW 801 will have 1700 PS for take off, but for the fighters the altitude power was a much more important thing. We know that P-40s and P-39s with 1600 HP at 2500 ft were nothing fancy above 15000 ft.



Hello Tomo Pauk,
Eventually the BMW 801D-2 became pretty reasonable with C-3 injection and even made some pretty impressive power without any power adders. It certainly was heavy for the amount of power though.
It is hard to disagree that the DB 605 was a better engine in the long run, but early versions were not just derated, they were unreliable.
As for a comparison with the single speed V-1710 engines, there is a pretty big difference between a critical altitude of 13,000 feet and one that is pretty close to 20,000 feet.



tomo pauk said:


> We can also make a speculation how interested was Germany in investing money in a private compaby that DB was, vs. in the government-owned Jumo in the time Germany beliveed that the've won the war? For whatever the reason, production of DB engines stayed about the same from late 1939 to late 1940, while production of Jumo engines doubled in the same time.
> Note that I don't advocate cancelling the BMW 801s, they can come in handy on Ju-88s, a small Ju 288, and later, f/b versions of Fw 190. What I'd cancel is the Bf 110 and subsequent 210 programe by winter of 1940/41.



I believe Kurt Tank was also of the opinion that the ultimate FW 190 would be powered by a Daimler Benz engine but was told that while he could experiment as much as he wanted, there simply would not be production quantities of those engines available to him.
Those early JuMo engines of that period were not really suited to use in fighters.
Without a pressurized cooling system, the radiators tended to be much larger because of lower efficiency.
As a general observation, the organizations within the Axis powers did not appear to work well together and seemed reluctant to share information with each other.

- Ivan.

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## Shortround6 (Jun 1, 2019)

Ivan1GFP said:


> Hello Shortround6,
> This comment surprises me a bit.
> The lack of development of a two stage or even a two speed supercharger seems like a serious mistake.
> The theory was that Turbochargers would be used when needed for high altitude performance but that doesn't seem to have worked well with the smaller aircraft.




As with all generalities there are some holes. However:
Who else in 1940 had a 1600hp radial engine in production (over 1900 built in 1940) ? with a two speed supercharger?
Who else was working on a 1700hp radial that would enter production in 1941?
Who else had an 1850hp engine going into production at the end of 1940 (2 speed)? 
Who else had a two stage engine in production in 1940?
Wright was offering two speed engines in 1938. 
Who else had turbo superchargers in production in 1940?

So I would say that the US was in pretty good shape in regards to engines compared to the rest of the world in the 1939-41 time period. 

Granted the US had a few clangers, or more than few, The Wright Tornado and early R-3350s come to mind. But the US had enough different engines that proved powerful and reliable to supply power for _most_ of their needs. The French, Italians, Russians and Japanese weren't even in the same league (in part due to fuel but two row radials without a center bearing weren't going anywhere) and it took the Germans several years to get a radial up to the power of the early US radials (R-2600 A series).


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## wuzak (Jun 1, 2019)

Zipper730 said:


> When did H2S & H2X become first available for night-bombing operations?





wuzak said:


> 1943.





Zipper730 said:


> Okay, so radar additions would not have been available until then. I would assume you'd mount it behind the bomb-bay on the lower fuselage like how it was done on the Avro Lancaster?



I should clarify.

H2S Mk.I was used, in small numbers, in January 1943. The Mk.I was essentially the pre-production version of the Mk.II, which came into widespread service ~July 1943.

H2S Mk.III, which had better resolution due to using a shorter wavelength and was equivalent to the H2X, began use in December 1943.

H2X was first used in combat in November 1943.


Initially H2X was fitted behind the chin turret on B-17Gs. Most were fitted in place of the ball turret. 

http://www.482nd.org/sites/default/files/2016-09/B-17-23511.jpg
How H2X "Mickey" – Got its name | 482nd Bombardment Group (P) 


Lancasters had them in the rear fuselage (where the under turret was fitted on some Manchesters).

For the Mosquito it took up the bomb bay! 
Royal Air Force RAF de Havilland Dh-98 Mosquito B-16 'H2S' Radar Scanner Fitted in the... 

Probably why they didn't use Mosquitoes with H2S.


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## davparlr (Jun 1, 2019)

Greg Boeser said:


> Zipper730,
> The short, symmetrical wing was chosen because that met the Army's requirements for high speed, but at the cost of higher stall speeds, longer take offs. The B-25 used a more conventional airfoil and though it cost speed, it improved low speed handling, improved take off performance.
> In a way the B-26 tried to meet as many expectations of the Army's requirement as physically possible, using the technology available at that time, but sacrificed much to achieve it.
> The A-26, which began design just a year later, exceeded the B-26 in virtually every category. But it was designed under a different set of requirements.
> The existence of the A-26 is the reason that many proposed improvements were not made to the B-26. The Army froze development on the B-26 and cancelled contracts as the A-26 neared gestation. The B-26 was costly to build, and the A-26 promised to be an improvement at a similar cost, so why invest more $$$ into an obsolescent design? The B-25 continued in production because it was cheaper and a tamer handler.


To beat an old drum of mine, putting the big wing on the B-26 was the error. Instead, the AAF, and Navy should have started addressing adapting to faster flying, and landing, aircraft, which was the future. This adaptation must include pilot training and, also, launch and landing platforms, that is, runways and aircraft carriers (the Navy was ill-adapted to deal with the fast flying air battles of the Korean War, only five years after WW2).
Given that, I think many lives would have been saved over Germany in 1943 if the AAF had built the XB-33A, only with R-2800 engines instead of the R-2600 and maybe with the P-47B turbochargers. This plane would be well over 250 mph cruise and 350 mph dash speed at 25000 ft. (I wouldn't sweat the pressurization, I would design to it but not press meeting it. Get the planes into the air!). In order to provide engines and manufacturing facilities, cancel my beloved B-26s.


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## BiffF15 (Jun 1, 2019)

Okay, my input is simple.

Have a Rolls-Royce design a supercharger for the V1710, then update it it regularly as they made advances on the Merlin.

Faster and better performing P-40s, P38s, P-39s and P-51As...

The follow up would be what could you do performance wise with Merlin type power at altitude with those aircraft?

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## Zipper730 (Jun 1, 2019)

BiffF15 said:


> Okay, my input is simple.
> 
> Have a Rolls-Royce design a supercharger for the V1710, then update it it regularly as they made advances on the Merlin.


Would that be feasible?


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## GrauGeist (Jun 2, 2019)

BiffF15 said:


> Okay, my input is simple.
> 
> Have a Rolls-Royce design a supercharger for the V1710, then update it it regularly as they made advances on the Merlin.
> 
> ...


The question is, how long would that take to go from concept to production and what changes in the V-1710 would need to be made in order to accept the add-on?

And, would those changes slow existing production?


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## Greg Boeser (Jun 2, 2019)

I find it interesting that the early (pre-war) users of the B-26 didn't have that much trouble with them. It was the first generation expansion pilots that were killing themselves with abandon in 1942. By 1943 the accident curve had swung way down, but by that time the decision had been made to kill the program. 
Another point that is often overlooked when talking about the "Widowmaker" is that it had a far better accident rate than the A-20 or A-26, though I suspect that as the A-26 matured it's accident rate curved down as well.

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## wuzak (Jun 2, 2019)

BiffF15 said:


> Okay, my input is simple.
> 
> Have a Rolls-Royce design a supercharger for the V1710, then update it it regularly as they made advances on the Merlin.
> 
> ...





Zipper730 said:


> Would that be feasible?



Allison tested a V-1710 with a Merlin 2 stage supercharger, but not directly connected. The performance was very much the same as the Merlin.

The Merlin supercharger could have been fitted - but the extent of the modifications to the engine and supercharger may be too much.

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## wuzak (Jun 2, 2019)

I should also mention that the supercharger bearings failed due to operating under different conditions than it would on the Merlin.


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## tomo pauk (Jun 2, 2019)

Shortround6 said:


> This kind of goes with using existing guns/technology or speeding up development of some guns or it could have been built?
> When did the 90 round drums show up? and will they fit in a 109 wing?
> By the time the Japanese had belt fed Oerlikons the Germans were using the MG 151 making the point rather moot.
> In any case even with the 15mm MG 151 a bit more firepower wouldn't hurt. ANd with the DB 601 engine situation the way if was (DB 601N engine good for 1175 hp at 4800 meters) it iis going to be a careful balance between firepower and performance.



Thing with MG 151 is that it will be a very problematic fit (will not say impossible) within the confines of the wing of Bf 109, having a bigger receiver, and using bigger ammo.
The 90 rd drum was probably of early 1943 vintage? German take on belt-feed MG FFM involved electrical motor, vs. Japanese cannons belt feed being powered by gun operation itself. MG FFM being a pretty light cannon will help out here - for example, three of those will weight less than two MG 151s (two FFMs will weight like one Hispano II), and will have lighter and more slender ammo. Granted, I'm trying to solve the problem of 1939/40 with a cure from 1943 here. Unlike Anglo-American fighters, German fighters were small & mostly light, so the 601N and early 601E will cut it here for 1941, even for 1942.



> one source says they only built about 180. That could be solved (put back into production) but in 1942 the MK 101 is too light a gun. And it only fires about 50% faster than the 37mm gun. One or two more shots per barrel per attack?
> For attacking soft targets four MG 17s seems to be a decent change even if not spectacular.



Yes, adding an extra pair of MG 17s does not tip the scales, but it doubles the rate of fire.
Two MK 101s beat a single MK 101 carried by early Hs 129Bs  Granted, by 1942/43 something bigger can/need to be added, 37mm is a good choice.




> I have a bit of a soft spot for the old He 111, it was supposed to be replaced several times but it never happened and in the meantime they kept using it with pretty much 1940 defensive guns and pretty much 1940/early 1941 engines. It didn't get an MG 131 in the dorsal position until 1942 (He 111H-11?) The power turret, which was power only in traverse(?) came later, a modification kit to the H-16. granted it was never going to fight it's way into a a target but better defence might have helped the loss rate. Same with the engines, a bit more speed or more speed and altitude when flying on one engine?



He 111 really deserves the BMW 801s (or something better, that either didn't materialized, or materialized too late). The 801A that powered early Do 217s was a reasonably reliable engine (probably due to not having 'option' for Notleistung?). One MG 131 will not cut it in dorsal position, have two there at least? Or, let's steal the idea from the British and have a 4-gun turret with MG 17s?



> This one is really curious as most of the early 1930s fighter (biplanes) and attack planes carried drop tanks or jettisonable tanks. I have never heard of any problems but that seems a rather sort period of time to forget about them unless there were problems.



Looking at the pics at the AHT, seems like mostly USN fighters were carrying drop tanks - making the drop tanks look indeed like the work of devil in the eyes of the USAAC/AAF 



> I am thinking even earlier when around 25% or more of the Bf 110s that attacked Poland used Jumo 210 engines and the large number of 109Ds that were built using Jumo 210s after the DB engines were used in air races in Switzerland.
> I don't know if DB was starved for funds or what was going on but even the He 111 went from using DB 601s on the P to Jumo 211s on the H (which actually came later)



Okay, got it now. 
My cunning plan does not involve Daimlerized Fw 190s fighting in Poland, but Fw 190s in early 1941 that don't burn due to engines, while having much better range/radius than Bf 109, as well as better rate of roll, cockpit, landing gear and armament.



> If you do have an extra DB engines floating around perhaps a better use for them than a DB powered FW 190 would be more Do 215 bombers? It was a close to German Mosquito as you were going to get early in the war.



Nah, I don't rate the Do 215 as close to even early Mosquito - no speed, you know  We might as well bomb-up Bf 110Cs.


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## tomo pauk (Jun 2, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> Eventually the BMW 801D-2 became pretty reasonable with C-3 injection and even made some pretty impressive power without any power adders. It certainly was heavy for the amount of power though.
> It is hard to disagree that the DB 605 was a better engine in the long run, but early versions were not just derated, they were unreliable.
> As for a comparison with the single speed V-1710 engines, there is a pretty big difference between a critical altitude of 13,000 feet and one that is pretty close to 20,000 feet.



If only there was a 1-stage V-1710 with the critical altitude of 20000 ft - the best in-service version went to 15500 ft (for 1125 HP) by late 1943/early 1944.
Thing with C3 injection was that it worked under 1.5 km of altitude. What BMW 801D needed, apart from reliability in 1st 6 months of service use, was a better supercharger from mid-1943, that eventually was in service by late 1944 with 801S - too late, that is.
The (un)reliability of DB 605As was not so acute as with BMW 801s in the first ~15 months of service with Fw 190s, that acute that it almost killed the whole Fw 190 program with engine itself. Let's note that DB 605A still have had no restrictions on 30-min regime, or any other lower regime, while restrictions on the BMW 801D were applied for all regimes.



> I believe Kurt Tank was also of the opinion that the ultimate FW 190 would be powered by a Daimler Benz engine but was told that while he could experiment as much as he wanted, there simply would not be production quantities of those engines available to him.
> Those early JuMo engines of that period were not really suited to use in fighters.
> Without a pressurized cooling system, the radiators tended to be much larger because of lower efficiency.
> As a general observation, the organizations within the Axis powers did not appear to work well together and seemed reluctant to share information with each other.
> - Ivan.



The people at RLM tried to install the DB 603s into the war-winning Me 410 - whoops...
Nobody used open cooling system on liquid-cooled engines from some time of 1930s? Granted, the over-pressure cooling systems, like what was introduced with DB 601E and Jumo 211F will enable for no increase of radiator size despite the increase of power.
The internal (in)efficiencies of within Axis powers are story for itself.


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## Shortround6 (Jun 2, 2019)

tomo pauk said:


> Thing with MG 151 is that it will be a very problematic fit (will not say impossible) within the confines of the wing of Bf 109, having a bigger receiver, and using bigger ammo.
> The 90 rd drum was probably of early 1943 vintage? German take on belt-feed MG FFM involved electrical motor, vs. Japanese cannons belt feed being powered by gun operation itself. MG FFM being a pretty light cannon will help out here - for example, three of those will weight less than two MG 151s (two FFMs will weight like one Hispano II),.



I don't know how big a difference there was in the thickness of the wings on th e109 and Zero where the guns (and ammo) were located. I mean actual thickness, not percentage as the Zeros wing was a lot bigger. Even a few inches might make a difference. 
The MG FF and FF/M had the dual problems of low rate of fire and poor velocity. You need more than two to get a large number of shells in the air, and you have to get close or use angles of fire with little deflection. The long time of flight making deflection shooting difficult. 



> Two MK 101s beat a single MK 101 carried by early Hs 129Bs



Ah, but one in/on the fuselage is worth two in the wings..... or so we are told 



> He 111 really deserves the BMW 801s (or something better, that either didn't materialized, or materialized too late). The 801A that powered early Do 217s was a reasonably reliable engine (probably due to not having 'option' for Notleistung?). One MG 131 will not cut it in dorsal position, have two there at least? Or, let's steal the idea from the British and have a 4-gun turret with MG 17s?



They did manage to power some of them with Jumo 213s once they stopped making 211s so it seems like there was no insurmountable difficulty in using more powerful engines. 

A manned turret with two MG 131s with power traverse and power elevation (both with fine control and not just rough slew) might have done wonders for a number of large german planes. In 1941 even a pair of MG 81s (not necessarily the MG 81Z) is going to beat the heck out of a MG 15. 



> Nah, I don't rate the Do 215 as close to even early Mosquito - no speed, you know  We might as well bomb-up Bf 110Cs.



Well, the Do 215 was rated at just about 500kph. Since the bombs are carried inside it doesn't take the performance hit that strapping bombs to the bottom of the 110 would cause so the actual attack speeds (30 minute rating?) would be a lot closer. Get rid of the "bug-eye" nose and put on something like the night fighter nose. Use DB 601N or E engines (mainly to get the altitude up higher than the DB601A and DB601Aa. You also have a more range than the 110. Possibility of trading bomb bay space for more fuel. Just do something about the idiotic gun array at the rear of the canopy. 

It will never equal the Mosquito but since you could have them almost 2 years before the Mosquito shows up in any numbers it doesn't have to be quite as good. 
The JU-88 was never going to equal the Mosquito either as by the time you get to the A-4 (very late 1940/early 41) you have plane weighing thousands of pounds more.


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## tomo pauk (Jun 2, 2019)

Shortround6 said:


> I don't know how big a difference there was in the thickness of the wings on th e109 and Zero where the guns (and ammo) were located. I mean actual thickness, not percentage as the Zeros wing was a lot bigger. Even a few inches might make a difference.
> The MG FF and FF/M had the dual problems of low rate of fire and poor velocity. You need more than two to get a large number of shells in the air, and you have to get close or use angles of fire with little deflection. The long time of flight making deflection shooting difficult.



The FF fired at 540 m/s, vs. the FFM at 700 m/s for the M-shell, so I'd say that FFM will give pilots a good chance to hit. Three FFMs will not be too heavy - circa 80 kg worth of cannons + ammo weight. Granted, we must wait to DB 601N so the central cannon can be installed, the 601A was a show stopper in that regard.
WRT to Bf 109s wing thickness - Spanish managed to install the big HS 404 cannon on their Buchons, after fiddling a bit with wing internals.



> Well, the Do 215 was rated at just about 500kph. Since the bombs are carried inside it doesn't take the performance hit that strapping bombs to the bottom of the 110 would cause so the actual attack speeds (30 minute rating?) would be a lot closer. Get rid of the "bug-eye" nose and put on something like the night fighter nose. Use DB 601N or E engines (mainly to get the altitude up higher than the DB601A and DB601Aa. You also have a more range than the 110. Possibility of trading bomb bay space for more fuel. Just do something about the idiotic gun array at the rear of the canopy.



It was rated by manufacturer at 500 km/h. And by the user? Granted, insisting on the slim nose might gain a few km/h.
It was also listed as capable for 20 x 50 kg of bombs only, again by manufacturer - less than 1/2 kg of bombs per HP installed, and 50 kg bombs will not impress with their destructive power. No dive bombing means less accuracy. Waiting for 601N, let alone 601E engines means it's already 1941? Perhaps it is better to have actual escort fighters for proper bomb trucks that can carry twice the bomb load, or more?
Trading of bomb bay space for more fuel is self-defeating here IMO.



> It will never equal the Mosquito but since you could have them almost 2 years before the Mosquito shows up in any numbers it doesn't have to be quite as good.
> The JU-88 was never going to equal the Mosquito either as by the time you get to the A-4 (very late 1940/early 41) you have plane weighing thousands of pounds more.



The Do 215 does not have to be as good as Mosquito, it needs to be that good so it can reliably evade RAF fighters. At 500 km/h for 5 minutes (say we believe manufacturer's figures) in mid 1940, it might evade Hurricane squadron that is about to take off, but probably not the other squadron that has 3000 ft advantage in height, let alone squadron of Spitfires. What happens once the 5 min limit is out, and Do 215s fly at 480 km/h?
Ju 88 as a bomber was an exercise in self-inflicted wounds, from the wrong position of wing/fuselage juncture onward.


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## fliger747 (Jun 2, 2019)

The comment was interesting about the B26 pilots needing to adapt to faster landing aircraft. I did the flight dynamics for a FSX B26 and was struck by this. The landing pattern and speeds were more like the ones that you might use flying the pattern in a light weight 737! Flying it as I would one of the jets, it was a quite pleasant plane to fly, if not having the jet like climb!


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## Ivan1GFP (Jun 2, 2019)

Shortround6 said:


> As with all generalities there are some holes. However:
> Who else in 1940 had a 1600hp radial engine in production (over 1900 built in 1940) ? with a two speed supercharger?
> Who else was working on a 1700hp radial that would enter production in 1941?
> Who else had an 1850hp engine going into production at the end of 1940 (2 speed)?
> ...



Hello Shortround6,
No question there was developed engine technology in the pre-war US, but with one notable exception: There wasn't a multi stage supercharged inline unless you used turbos which were not quite ready for service.
This was a strange oversight especially since the US Army was showing a preference for inline engines in the most recent designs and updates such as from P-36 to P-40.
One has to wonder how history would have changed had the Merlin engine not been made available for production in the United States.
There was a mad scramble after the war when the US was no longer able to produce Merlins without paying royalties to RR.



Shortround6 said:


> Granted the US had a few clangers, or more than few, The Wright Tornado and early R-3350s come to mind. But the US had enough different engines that proved powerful and reliable to supply power for _most_ of their needs. The French, Italians, Russians and Japanese weren't even in the same league (in part due to fuel but two row radials without a center bearing weren't going anywhere) and it took the Germans several years to get a radial up to the power of the early US radials (R-2600 A series).



The R-3350 did eventually become a mostly reliable and dependable power plant but that didn't happen until after the was was over. Every country seemed to have its share of "clangers" for whatever reason.

- Ivan.


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## Ivan1GFP (Jun 2, 2019)

tomo pauk said:


> If only there was a 1-stage V-1710 with the critical altitude of 20000 ft - the best in-service version went to 15500 ft (for 1125 HP) by late 1943/early 1944.



Hello Tomo Pauk,
The problem was that those V-1710 with the higher altitude ratings were the two speed supercharged versions and didn't have the same ridiculously high emergency ratings at sea level.



tomo pauk said:


> Thing with C3 injection was that it worked under 1.5 km of altitude. What BMW 801D needed, apart from reliability in 1st 6 months of service use, was a better supercharger from mid-1943, that eventually was in service by late 1944 with 801S - too late, that is.
> The (un)reliability of DB 605As was not so acute as with BMW 801s in the first ~15 months of service with Fw 190s, that acute that it almost killed the whole Fw 190 program with engine itself. Let's note that DB 605A still have had no restrictions on 30-min regime, or any other lower regime, while restrictions on the BMW 801D were applied for all regimes.



With the BMW 801, eventually it was able to achieve about the same power without C-3 injection or any other power adder.
No argument with the your other discussion. The BMW 801 was hardly trouble free initially.
One has to wonder if the Germans were being overly cautious though. Faber's captured FW 190A apparently was one of the de-rated versions but was flown in testing as if it were not and did not seem to run into any problems as a result. One would assume that a captured aircraft would not have particularly good supply chain for maintenance purposes.

- Ivan.


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## Shortround6 (Jun 2, 2019)

tomo pauk said:


> The FF fired at 540 m/s, vs. the FFM at 700 m/s for the M-shell, so I'd say that FFM will give pilots a good chance to hit. Three FFMs will not be too heavy - circa 80 kg worth of cannons + ammo weight. Granted, we must wait to DB 601N so the central cannon can be installed, the 601A was a show stopper in that regard.
> WRT to Bf 109s wing thickness - Spanish managed to install the big HS 404 cannon on their Buchons, after fiddling a bit with wing internals.



You are comparing the velocity for different weight shells. Always a problem for German 20mm guns 
Some sources say 600m/s for the MG/FF but in any case it was for 134 gram projectile.
The 700m/s was for the 92 gram mine shell but the mine shell lost velocity much quicker. actual time of flight to 300 meters was much closer than the muzzle velocity would suggest. At some point short of 300 meters the heavier shell would have passed the lighter one with the higher velocity. This is at sea level, at higher altitudes things aren't quite so bad. 

The 92 gram shell lost (at sea level) 38% of it's velocity by 300 meters. The 7.9mm AP round lost 33% but since it had a higher velocity to begin with it actually reached 300 meters about 0.1 seconds quicker. the US. 50 cal only lost about 15% of it's velocity in the first 300 meters. 
As the infamous mine shell will not carry either tracer or incendiary the Germans had to come up with a "standard" shell that would function with the same weight of recoiling parts and mainspring as the mine shell used. the result was a 115-115 gram projectile at 585 m/s that lost around 23% velocity (or bit less) at 300meters. 

This set up may work perfectly well against 1939-42 bombers (at least most of them) but may be a bit lacking in fighter vs fighter combat. The MG 151 15mm lacked "punch" but it was a lot easier to hit with. 





> It was rated by manufacturer at 500 km/h. And by the user? Granted, insisting on the slim nose might gain a few km/h.
> It was also listed as capable for 20 x 50 kg of bombs only, again by manufacturer - less than 1/2 kg of bombs per HP installed, and 50 kg bombs will not impress with their destructive power. No dive bombing means less accuracy.



The Bf 110 couldn't really dive bomb either. It was claimed that the do 17z could do 600kph in a dive. So strength and control; was already there for at least a steep glice bomb attack.
Bomb loads are iffy, If you have any manuals please post? Some sources claim two or four 250kg bombs and few claim or hint at two 500kg bombs. Depending on how they are hung 20 50kg bombs can take up a fair amount of room (B-26 would only hold 30 equivalent bombs even using the rear bomb bay). Unfortunately photos are rare? 



> Waiting for 601N, let alone 601E engines means it's already 1941? Perhaps it is better to have actual escort fighters for proper bomb trucks that can carry twice the bomb load, or more?
> Trading of bomb bay space for more fuel is self-defeating here IMO.


The Do 215 certainly could not replace the He 111 or even the JU 88 for some missions. But since the 215 could outrun a JU 88A-4 it would seem that some use might be found for it. 
If you go the four 250kg bomb route there may be room in the top of the bomb bays for fuel tanks. five 50 kg bombs stacked on top of each other take up vertical space. Or the ever popular aux tanks out board of the engines. 
Maybe the bomb doors would need to be bulged? In any case the Mosquito was pretty much limited to four 500lbs until 1944 and even then not all bombers carried much more on every mission. 
It might give you an airplane to use all those engines that were supposed to go into Me 210s  
I am sure they found a use for them. 





> The Do 215 does not have to be as good as Mosquito, it needs to be that good so it can reliably evade RAF fighters. At 500 km/h for 5 minutes (say we believe manufacturer's figures) in mid 1940, it might evade Hurricane squadron that is about to take off, but probably not the other squadron that has 3000 ft advantage in height, let alone squadron of Spitfires. What happens once the 5 min limit is out, and Do 215s fly at 480 km/h?
> Ju 88 as a bomber was an exercise in self-inflicted wounds, from the wrong position of wing/fuselage juncture onward.



While it may have to evade British fighters (Spitfires) over England, what it has to evade in the Balkans, and NA in 1941 are rather different, not to mention what it has to evade in Russian in 1941/42. Not the best the Russians have but the Average that the Russians have. With DB601Ns or DB601Es it might only be 15-25mph slower than the PE-2?


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## tomo pauk (Jun 2, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> The problem was that those V-1710 with the higher altitude ratings were the two speed supercharged versions and didn't have the same ridiculously high emergency ratings at sea level.



Several problems, actually. The V-1710s with the higher altitude ratings were the 2-stage supercharged versions, no 2-speed supercharged V-1710 ever entered service. Then, 2-stage V-1710s were used by a redundant aircraft - the P-63. Too late in the game, too - Autumn of 1943, in what time the Allies have had a firm grip on the things aircraft-related (plus, we have Germany sufferign crushing defeats on all fronts and in retreat by that time). The 2-stage V-1710s with water injection have had even greater emergency ratings at low altitudes, going to 1850 HP.





> With the BMW 801, eventually it was able to achieve about the same power without C-3 injection or any other power adder.
> No argument with the your other discussion. The BMW 801 was hardly trouble free initially.
> One has to wonder if the Germans were being overly cautious though. Faber's captured FW 190A apparently was one of the de-rated versions but was flown in testing as if it were not and did not seem to run into any problems as a result. One would assume that a captured aircraft would not have particularly good supply chain for maintenance purposes.
> 
> - Ivan.



No doubt that BMW 801 earned it's place in aircraft history. What it lacked in early service was reliability, and later (mid/late 1944 on) it lacked a better supercharger. We also have a thing that 801 was not not contributing to the Axis cause for the 1st 20-22 (24?) moths of the war - 'my' RLM would've supported BMW staying in V12 business even after they acquired Bramo.


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## Shortround6 (Jun 2, 2019)

Ivan1GFP said:


> Hello Shortround6,
> No question there was developed engine technology in the pre-war US, but with one notable exception: There wasn't a multi stage supercharged inline unless you used turbos which were not quite ready for service.
> This was a strange oversight especially since the US Army was showing a preference for inline engines in the most recent designs and updates such as from P-36 to P-40.
> One has to wonder how history would have changed had the Merlin engine not been made available for production in the United States.





Ivan1GFP said:


> Hello Tomo Pauk,
> The problem was that those V-1710 with the higher altitude ratings were the two speed supercharged versions and didn't have the same ridiculously high emergency ratings at sea level.



I would note that the British didn't get a multi stage supercharged inline into service until 1942. They weren't even working on it in 1940 so blaming the US for not pursuing that avenue seems a bit harsh. Especially considering that the British were not pursuing the turbo option at all. The P & W Two stage radial went into production about 2 years before RR got the the two stage Merlin into production. 
The RR single stage superchargers were better than what the US using. Much better after Hooker worked on them. 
The Allisons that had the 15,500ft altitude rating were single speed engines. Allison didn't get a two speed engine built until either the end of the war or just after, quantity was minuscule with four being intended for an Allison powered DC-4 plus a few test engines. 

One does wonder what would have happened without Packard. Packard was initially contracted to build 9000 single stage , two speed engines, this contract was fulfilled in the beginning of March of 1943. But Packard didn't totally change over to two stage engines, further contracts saw them build almost 7200 single stage engines in 1944 of which the US got none, This is added to the over 10,000 single stage engines they built in 1943 of which the US got none. 

I do believe that one or two Short Stirlings were trialed with Wright R-2600s and perhaps they could have been used on the Halifax?


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## Shortround6 (Jun 2, 2019)

tomo pauk said:


> my' RLM would've supported BMW staying in V12 business even after they acquired Bramo.



I don't have any details on a large BMW V-12 but the BMW 116 wasn't going to do the job
BMW 116 - Wikipedia 

There may have been nothing wrong with it except being of the same size and power as the Jumo 210 and Kestrel, which means either starting over or unpacking the pantograph and scaling it up.


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## tomo pauk (Jun 2, 2019)

Shortround6 said:


> You are comparing the velocity for different weight shells. Always a problem for German 20mm guns
> Some sources say 600m/s for the MG/FF but in any case it was for 134 gram projectile.
> The 700m/s was for the 92 gram mine shell but the mine shell lost velocity much quicker. actual time of flight to 300 meters was much closer than the muzzle velocity would suggest. At some point short of 300 meters the heavier shell would have passed the lighter one with the higher velocity. This is at sea level, at higher altitudes things aren't quite so bad.
> 
> ...



I can't compare M-shell data for the FF since it could not fire it, unlike the FFM.



> This set up may work perfectly well against 1939-42 bombers (at least most of them) but may be a bit lacking in fighter vs fighter combat. The MG 151 15mm lacked "punch" but it was a lot easier to hit with.



German pilots were managing to kill a sizable number of Allied fighters even with the FF in 1939-40, the FFM will give them better chances. As long as they fire under 300-350m (just like RAF did, once the data was collected).



> The Bf 110 couldn't really dive bomb either. It was claimed that the do 17z could do 600kph in a dive. So strength and control; was already there for at least a steep glice bomb attack.
> Bomb loads are iffy, If you have any manuals please post? Some sources claim two or four 250kg bombs and few claim or hint at two 500kg bombs. Depending on how they are hung 20 50kg bombs can take up a fair amount of room (B-26 would only hold 30 equivalent bombs even using the rear bomb bay). Unfortunately photos are rare?



Curiously enough, unlike with Do 17s, only 50 kg bombs are listed (20 of them). Manual is here: link
The Bf 110C was rated for 650 km/h in dive.



> The Do 215 certainly could not replace the He 111 or even the JU 88 for some missions. But since the 215 could outrun a JU 88A-4 it would seem that some use might be found for it.
> If you go the four 250kg bomb route there may be room in the top of the bomb bays for fuel tanks. five 50 kg bombs stacked on top of each other take up vertical space. Or the ever popular aux tanks out board of the engines.
> Maybe the bomb doors would need to be bulged? In any case the Mosquito was pretty much limited to four 500lbs until 1944 and even then not all bombers carried much more on every mission.
> It might give you an airplane to use all those engines that were supposed to go into Me 210s
> I am sure they found a use for them.



Granted, the previous Do 17s were able to carry 250 kg bombs, so perhaps that could be shoehorned in the 215s? All/any of the extra DB 601 engines will end up in Fw 190s or Italian fighters, the Me 210 program is axed come 1941.
Mosquito (bomber version) was slower by perhaps 2-3% than fastest LW interceptors? As above - Ju 88 was an exercise how to un-make fast bomber.



> While it may have to evade British fighters (Spitfires) over England, what it has to evade in the Balkans, and NA in 1941 are rather different, not to mention what it has to evade in Russian in 1941/42. Not the best the Russians have but the Average that the Russians have. With DB601Ns or DB601Es it might only be 15-25mph slower than the PE-2?



It will not need to evade anything in Balkans, since even historical LW bombers have had easy task there due to Yugoslavs and Greeks having radar-less and otherwise obsolete air defences. 
NA and Eastern front in 1941 might get me Fw 190s - long range, rate of roll and all of that...


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## tomo pauk (Jun 2, 2019)

Shortround6 said:


> I don't have any details on a large BMW V-12 but the BMW 116 wasn't going to do the job
> BMW 116 - Wikipedia
> 
> There may have been nothing wrong with it except being of the same size and power as the Jumo 210 and Kestrel, which means either starting over or unpacking the pantograph and scaling it up.



Wrong BMW - this one was in my mind: BMW 117 - a 36 L engine.
Unless they make something of ~45L with know-how and technology of mid/late 1930s.

To move a bit from Luftwaffe. 
- Hurricane & Sea Hurricane: beard radiator, better carbs, props and exhausts, a bit thinner wing from the get go. Also even more firepower. Folding wings for the S-H.
- MiG-3 with proper canopy, AM-38 (later AM-39) and two cannons
- Zero and Oscar with Kinsei from day one
- Ki-61 with Ha-109, later with Homare

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## Shortround6 (Jun 2, 2019)

First thanks for the link to the manual 



tomo pauk said:


> I can't compare M-shell data for the FF since it could not fire it, unlike the FFM.


No but the Germans had some problems coordinating fire. If we are going to trouble of designing ideal aircraft why are we using 2nd rate armament? 





> German pilots were managing to kill a sizable number of Allied fighters even with the FF in 1939-40, the FFM will give them better chances. As long as they fire under 300-350m (just like RAF did, once the data was collected).


 The MG FFM had a few problems, yes it was better than A machine (or even two) but you have the drum feed problem and the mixed ammo load problem, sometimes only 40% of the ammo was the mine shell. Bigger drums are not a real problem for the fuselage mounted gun but more of a problem with the wing mounted guns. Japanese may have shifted to some sort of box magazine? details/translations are not good. When you are dealing with 1000-1200hp there is only so much you can do, but when better engines are available (and faster targets) it doesn't give quite the return for investment. 





> Curiously enough, unlike with Do 17s, only 50 kg bombs are listed (20 of them). Manual is here: link
> The Bf 110C was rated for 650 km/h in dive.


My German is practically non existent. In the early part of that manual is some reference to 650kph but I don't what it refers to. 

Blatt 4 (?) near the end of the first paragraph? 





> Granted, the previous Do 17s were able to carry 250 kg bombs, so perhaps that could be shoehorned in the 215s? All/any of the extra DB 601 engines will end up in Fw 190s or Italian fighters, the Me 210 program is axed come 1941.



The manual shows a picture of a bomb rack/dispense for 80 10 kg bombs. Later there are loadouts and diagrams for a dispenser(?) for 40 10 kg bombs. and/or 400kg of light bombs. 




> Mosquito (bomber version) was slower by perhaps 2-3% than fastest LW interceptors?



The 215 cruised 100-140kph faster than the Do 17z, with better engines? Not the immunity of a Mosquito but would present interception difficulties for an enemy without an integrated air defense. 
Nobody cruised at top speed. early Mosquitoes cruised at about 310mph max weak mixture at about 14,000ft. 





> It will not need to evade anything in Balkans, since even historical LW bombers have had easy task there due to Yugoslavs and Greeks having radar-less and otherwise obsolete air defences. .


Sorry, Balkans would include Greece/Crete with British intervention but still no radar. 


BTW the manual shows some rather strange drawings of a Zerstorer near the end. it appears to have a single cannon firing through each prop hub and no other changes to armament. 
Unsold proposal? Magazines under the gun? notes seem to indicate Oerlikon FFS guns which used the same ammo as Allied AA guns (very comparable to the Hispano. 
Export to Sweden?


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## gjs238 (Jun 2, 2019)

BiffF15 said:


> Okay, my input is simple.
> 
> Have a Rolls-Royce design a supercharger for the V1710, then update it it regularly as they made advances on the Merlin.
> 
> ...



My input would be for the original design of the V-1710 to be more modular, in particular, the supercharger.
The V-1710 was advertised as being designed with what they felt was great modularity: see Allison V-1710 - Wikipedia
But I wonder if perhaps a sidewinder supercharger arrangement would have increased modularity, allowing one of two superchargers to be installed without a major rework of the engine or resorting to a remote shaft driven 2nd stage supercharger.
In effect, the supercharger(s) would be accessorie(s) bolted to the engine.

PS: If nothing else, plan for a multi-speed supercharger from the get-go.

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## Kevin J (Jun 2, 2019)

tomo pauk said:


> Wrong BMW - this one was in my mind: BMW 117 - a 36 L engine.
> Unless they make something of ~45L with know-how and technology of mid/late 1930s.
> 
> To move a bit from Luftwaffe.
> ...


Like but disagree:-
Mig-3. No change. Discarded as unsuccessful design for Eastern Front. 
Sea Hurricane I from 1939 for service on carriers not Sea Gladiator. No folding wings ever as interim type pending arrival of Seafire. Sea Hurricane Ib (1939), IIb (1940), IIc (1941). Replaced by Seafire in 1942.
Spitfire III to form basis for Seafire to be put into production by Westland in 1941. Maybe Seafire Ic (c for carrier version) not Spitfire I's in 1941 for training, hook only and Merlin 20. Seafire IIc as per Spitfire III without folding wings in 1942 with late Merlin 20 series, but with hook and catapult spools. Seafire LIII as per Spitfire III with folding wings service intro early 1943 using Merlin 32, first deliveries late 1942. Cunliffe Owen to build Seafire XV based on Spitfire IV with Griffon engine service intro 1943, limited edition. Seafire FR 17 to appear in 1944. Should all be feasible. Supermarine leads the way for land based versions with Castle Bromwich being the mass producer. Westland uses their design skills to turn the Spitfire III/IV into World beating carrier fighters. 
Zero and Oscar with Kinsei from 1943 on.
Ki-100 service intro 1944. No Ki-61-II. Replaces Shoki phased out of production in favour of Ki-84. Performance not quite as high as Raiden but more reliable. Better range and dive speed.


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## Shortround6 (Jun 2, 2019)

Everything is trade-offs. 
Sidewinder superchargers require right angle drives. 
upside down Jumo 211





Not a great supercharger to begin with, it doesn't make for a shorter engine, especially as the supercharger gets bigger. Germans with fuel injection didn't have to worry about where to the carburetor. 
Right side up





Now try to fit the ducting from one supercharger to the other and hopefully an intercooler between the superchargers. Or even an after cooler between the last supercharger and the intake duct/manifold. 
I am not saying it won't work, only that it takes a lot to really improve on what they were doing 

The post war R-2800 used in the F4U-5 was a different beast.




The primary supercharger was still on the back of the engine and the TWO sidewinder superchargers ran in parallel, not series, they were driven by a variable speed drive with both impellers turning at the same speed. Photo does not show the ducting and intercoolers needed. that outlet on the right had side needs to go to the intercooler and then come back to the engine to the inlet for the main supercharger.

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## swampyankee (Jun 2, 2019)

Getting back to the "make it better" bit in the original post.

I think the P-61, with the intrinsic weight and drag added by the (imho) superfluous turret and gunner has the most obvious fix. Since I tend to think that turrets are fighters are nearly always completely superfluous, we could easily improve the Boulton-Paul Defiant and Blackburn Roc by getting rid of that monstrosity in both of them. Of course, the Roc has many more problems, starting with having too little engine.

The US aircraft I'd start with would be the P-39 and the P-38
For the P-39

The M-4 cannon was not particularly useful. Replace it with something like the 20 mm HIspano (its production problems were due to idiocy within the Army's bureaucracy, not intrinsic flaws in the manufacturing process).
The car-doors were dumb. I know they were fashionable (iirc, the Tempest started with the same arrangement). Sliding canopies were definitely the way to go.
One of the problems of the mid-engined layout is that it puts the engine, a big, heavy lump, exactly where one wants to put the fuel. While moving the engine would, in essence, change the P-39 to the P-40, fuel tankage could be increased by a small increase in wing span, and putting tanks in the wing roots.
The original XP-39 had such a poor turbocharger installation that it actually impaired performance at altitude by increased drag. I think this could be fixed by lengthening the fuselage to permit a proper installation. 
For the P-39:

You have liquid-cooled engines. I believe that the automotive industry had figured out how to heat a passenger compartment by the addition of a tiny radiator with air blown through it. I suspect some engineer or another at Lockheed would have been smart enough to get this to work.
Using the wing leading edge for cooling. Use a real heat exchanger.
There wasn't much to be done about the compressibility issue short of major redesign, so that's not an issue.
Of course, the real problem with the P-38 was inadequate pilot training. It was a large, complex airplane and was, insofar as I can remember, the first large twin-engined aircraft the USAAF operated without a co-pilot and possibly even a flight engineer.

Looking in hindsight, every single aircraft put into service in WW2 had problems of one level or another. For example, a couple of USN aircraft had manually retracted landing gear. The elegant, iconic, elliptical wing of the Spitfire was a bitch to manufacture. The Ju-87 had a remarkably draggy radiator installation.

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## Kevin J (Jun 2, 2019)

swampyankee said:


> Getting back to the "make it better" bit in the original post.
> 
> I think the P-61, with the intrinsic weight and drag added by the (imho) superfluous turret and gunner has the most obvious fix. Since I tend to think that turrets are fighters are nearly always completely superfluous, we could easily improve the Boulton-Paul Defiant and Blackburn Roc by getting rid of that monstrosity in both of them. Of course, the Roc has many more problems, starting with having too little engine.


Yes, get rid of the Roc, even though the Roc in Sinbad the Sailor was an apex predator. Other than that I disagree. The Defiant was right for its timescale service and the P-61 was designed around that time, so the concept was okay for its role as a night patrol interceptor. In service of course, the turret was useless as it was a predator not an interceptor.


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## swampyankee (Jun 2, 2019)

Kevin J said:


> Yes, get rid of the Roc, even though the Roc in Sinbad the Sailor was an apex predator. Other than that I disagree. The Defiant was right for its timescale service and the P-61 was designed around that time, so the concept was okay for its role as a night patrol interceptor. In service of course, the turret was useless as it was a predator not an interceptor.



We're all 20/20 in hindsight 

The RN could have had a decent fighter without having to buy from the Americans; the real problem with the Roc is that the people who wrote the spec were not sufficiently knowledgeable to write good specs, and the Roc was the result. The Defiant _may_ be more defensible, but I think its turret was the result of a poorly-conceived specification, although there were actually some two-seat biplanes, with a rear gunner, that were competitive, in air combat, with contemporary fighters.

As for the need for the turret on a night fighter: these were not used on, for example, Mosquito, Beaufighter, or P-70 night fighters. Why a turret was seen as necessary on the P-61, after it was shown unnecessary by successful radar-equipped night fighters, mystifies me.

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## PAT303 (Jun 2, 2019)

Can I ask why each manufacturer worked on different planes instead of the ones that they new worked?. Look at the Spitfire and Hurricane, they both worked as designed, why didn't someone higher up say to Boulton Paul/Fairey/DH/Wessex/Shorts your planes are rubbish, make Spitfires instead, likewise Rover/Austin/SS (Jaguar) make Merlins, is this idea feasible?.


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## wuzak (Jun 2, 2019)

PAT303 said:


> Can I ask why each manufacturer worked on different planes instead of the ones that they new worked?. Look at the Spitfire and Hurricane, they both worked as designed, why didn't someone higher up say to Boulton Paul/Fairey/DH/Wessex/Shorts your planes are rubbish, make Spitfires instead, likewise Rover/Austin/SS (Jaguar) make Merlins, is this idea feasible?.



MAP told Fairey to make a navalised Spitfire. Fairey said NO!


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## Shortround6 (Jun 2, 2019)

Using the Defiant as a night fighter was a waste of a target tug.

Now if somebody can list the air to air kills it made over the winter of 1940/41, from October to May, and if they come up to more than 16 (two per month average) I will retract that statement.

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## wuzak (Jun 2, 2019)

swampyankee said:


> For the P-39
> 
> The M-4 cannon was not particularly useful. Replace it with something like the 20 mm HIspano (its production problems were due to idiocy within the Army's bureaucracy, not intrinsic flaws in the manufacturing process).
> The car-doors were dumb. I know they were fashionable (iirc, the Tempest started with the same arrangement). Sliding canopies were definitely the way to go.
> ...



For the P-39 I'd have changed it into a pusher type with a Y-type tail (like the Bugatti P100), move the cockpit forward, install 2 x 20mm on each side of the nose (probably end up with 4 x 0.50", since it was American), possibly more fuel near the engine.

House the radiator below the fuselage, similar to the P-51. Who knows, you could even fit a turbo in that!


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## wuzak (Jun 2, 2019)

Shortround6 said:


> Maybe the bomb doors would need to be bulged? In any case the Mosquito was pretty much limited to four 500lbs until 1944 and even then not all bombers carried much more on every mission.



The Mosquito could carry 6 x 500lb bombs after the introduction of the universal wing in mid 1943.

I would also note that it was possible to carry 1 x 1000lb and 2 x 500lb, but that was not used operationally.


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## Shortround6 (Jun 2, 2019)

Sorry, I should have said four 500lb bombs internally. 

Germans were masters at hanging bombs on the outside but the performance with such drag producing configurations are rarely listed. 

The Mosquito seemed to take either drop tanks or a pair of 500lb bombs without too much of a hit to performance.


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## gjs238 (Jun 2, 2019)

wuzak said:


> For the P-39 I'd have changed it into a pusher type with a Y-type tail (like the Bugatti P100), move the cockpit forward, install 2 x 20mm on each side of the nose (probably end up with 4 x 0.50", since it was American), possibly more fuel near the engine.
> 
> House the radiator below the fuselage, similar to the P-51. Who knows, you could even fit a turbo in that!



How about something like this?
SAAB 21 - Wikipedia


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## wuzak (Jun 2, 2019)

gjs238 said:


> How about something like this?
> SAAB 21 - Wikipedia



That's what the XP-54 should have been (and similar to what was originally proposed).

That with a 2 stage Merlin pusher could have been quite good.

For the Saab 21, dump the 13.2mm mgs and 1 20mm for 4 x 20mm.

A ground attack version of the Saab 21 may have been able to fit a 40mm gun in the front of each boom.

Still would have kept the P-39 more conventional.


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## PAT303 (Jun 3, 2019)

wuzak said:


> MAP told Fairey to make a navalised Spitfire. Fairey said NO!



Well I suppose they were busy building masterpieces such as the Barracuda, a plane of such brilliance that it was replaced with the plane it was designed to replace!!!!!.


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## Zipper730 (Jun 3, 2019)

swampyankee said:


> The M-4 cannon was not particularly useful. Replace it with something like the 20 mm HIspano (its production problems were due to idiocy within the Army's bureaucracy, not intrinsic flaws in the manufacturing process).


I'm not sure why they classified 20mm cannon as anti-aircraft artillery. The USN did not do this. An aircraft mounted weapon can't always been built to the same standards as standard artillery.

Some of the decisions seemed odd, I was told that they enlarged the chamber: I have no idea why you'd do that unless they had flirted with the idea of making a bigger casing.


> The original XP-39 had such a poor turbocharger installation that it actually impaired performance at altitude by increased drag. I think this could be fixed by lengthening the fuselage to permit a proper installation.


Me and 

 P-39 Expert
did an intellectual exercise on that. It didn't seem to really work.

Short of totally redesigning the plane, you wouldn't be able to get the turbocharger in there.


wuzak said:


> For the P-39 I'd have changed it into a pusher type with a Y-type tail (like the Bugatti P100), move the cockpit forward, install 2 x 20mm on each side of the nose (probably end up with 4 x 0.50", since it was American), possibly more fuel near the engine.
> 
> House the radiator below the fuselage, similar to the P-51. Who knows, you could even fit a turbo in that!


A pusher would have been a bad idea, attempt to bail out and you turn into salsa.


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## Zipper730 (Jun 3, 2019)

wuzak said:


> That's what the XP-54 should have been (and similar to what was originally proposed).


It was supposed to be smaller, like the SAAB 21. That said, if I recall, the problem was mostly that it was originally designed for low/medium altitude operations. I'm not sure why they did that, as the USAAC seemed to generally favor high altitude aircraft

Y1P-37: Based on a P-36 with an inline engine and a turbocharger. The radiator & intercooler seemed to have screwed the design up. The P-40 was procured because it would be simple, and it turned out okay -- but it couldn't fly as high as the P-37
XP-39: Designed with a turbocharger, though it didn't fit well, and the design needed modifications that got rid of the turbo.
P-38: Designed as a high altitude fighter with supercharger, it was successful.
P-47: Designed with altitude capability in the overall design, and proved successful.


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## Zipper730 (Jun 3, 2019)

wuzak said:


> MAP told Fairey to make a navalised Spitfire. Fairey said NO!


You know, that would have been a good argument for designing the Firefly as a single-seater.

The design probably would have been lighter, and potentially a bit faster if it was free of the need of an extra crew-member, and things of that sort.


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## wuzak (Jun 3, 2019)

Zipper730 said:


> It was supposed to be smaller, like the SAAB 21.



I believe that's what I said.




Zipper730 said:


> That said, if I recall, the problem was mostly that it was originally designed for low/medium altitude operations. I'm not sure why they did that, as the USAAC seemed to generally favor high altitude aircraft



I don't believe it was designed as a low altitude aircraft. It was supposed to have higher performance than aircraft then in production and the performance of fighters in development.




Zipper730 said:


> Y1P-37: Based on a P-36 with an inline engine and a turbocharger. The radiator & intercooler seemed to have screwed the design up. The P-40 was procured because it would be simple, and it turned out okay -- but it couldn't fly as high as the P-37
> XP-39: Designed with a turbocharger, though it didn't fit well, and the design needed modifications that got rid of the turbo.
> P-38: Designed as a high altitude fighter with supercharger, it was successful.
> P-47: Designed with altitude capability in the overall design, and proved successful.



Don't know what we'd do without you.

Actually, the P-47 was designed as a light weight fighter powered by an altitude rated V-1710.

That was cancelled in favour of the P-47B, which was the turbo R-2800 aircraft.

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## GrauGeist (Jun 3, 2019)

swampyankee said:


> The car-doors were dumb. I know they were fashionable (iirc, the Tempest started with the same arrangement). Sliding canopies were definitely the way to go.


On the P-39, the cockpit was a modular structure and the canopy frame was part of the framework.
A conventional canopy would not have worked because of that and because of the air intake directly behind the cockpit.

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## swampyankee (Jun 3, 2019)

Pushers are cool, but also have a numbers of practical problems, pilots being minced being just one: the prop is operating in dirty air during flight, it’s more likely to get fodded by stones and gravel kicked up by the tires, and it either restricts AoA on takeoff and landing enough to increase both distances or it requires stalky, heavier landing gear. 

One of the flaws of the P-39’s mid-engine configuration is that Bell put this huge, massive lump right in the best place for the fuel tanks, and compounded that by putting heavy weights that would be discarded during combat far ahead of the c/g

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## Ivan1GFP (Jun 3, 2019)

tomo pauk said:


> No doubt that BMW 801 earned it's place in aircraft history. What it lacked in early service was reliability, and later (mid/late 1944 on) it lacked a better supercharger. We also have a thing that 801 was not not contributing to the Axis cause for the 1st 20-22 (24?) moths of the war - 'my' RLM would've supported BMW staying in V12 business even after they acquired Bramo.



Hello Tomo Pauk,
I guess the our "What-If" conditions are just a bit different. I was thinking minimal adjustments to the industry and fairly small changes in the existing environment while it seems like you were thinking of much larger series of cascading changes and management direction.

I had forgotten that the changes to the Allison engine series was mostly just a change in supercharger gear ratios.

- Ivan.


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## Simon Thomas (Jun 3, 2019)

Shortround6 said:


> I do believe that one or two Short Stirlings were trialed with Wright R-2600s and perhaps they could have been used on the Halifax?




From "Short Stirling, The First of the RAF Heavy Bombers" – Pino Lombardi 


> The Hercules II engines fitted to the Stirling Mk I were expected to be replaced by US-made Wright Cyclone engines for the Mk II. However, Hercules engine production was accelerated to meet demands, and when three aircraft-N3657, N3711, and R9188 -were fitted with Wright Cyclone engines at Swindon, performance and fuel consumption trials to assess performance and fuel consumption produced disappointing results. They offered no improvement over the Hercules and were much noisier, therefore a contract was not given.



HP would no doubt have been briefed on the performance of the Cyclone powered Stirlings.


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## tomo pauk (Jun 3, 2019)

Shortround6 said:


> No but the Germans had some problems coordinating fire. If we are going to trouble of designing ideal aircraft why are we using 2nd rate armament?
> The MG FFM had a few problems, yes it was better than A machine (or even two) but you have the drum feed problem and the mixed ammo load problem, sometimes only 40% of the ammo was the mine shell. Bigger drums are not a real problem for the fuselage mounted gun but more of a problem with the wing mounted guns. Japanese may have shifted to some sort of box magazine? details/translations are not good. When you are dealing with 1000-1200hp there is only so much you can do, but when better engines are available (and faster targets) it doesn't give quite the return for investment.



Nobody in 1939/40 have had ideal guns - they were either of a too light a punch, or could not be synchronised (or can, bad with great reduction in RoF), or have too small ammo count, or are too heavy for installed HP, or have low MV. A lot of countries don't even have cannons ins service in 1940 in more than token amounts.
We can't remove away the of limitation of a platform - Bf 109 will carry two small & light FFs, but how easily two Hispanos or equivalent? Important when we have 1000-1200 HP engines indeed. Two MG FF weight as much as one Hispano, they will throw ~1050 rd/min vs. 600 rd/min for one Hisso. Once DB 601N is in German fighters, they can carry another cannon in center position, for three cannons total (or a combination with HMGs).
German 90 rd drum was barely wider and taller than the 60 rd drum (Oerlikon was also offering 75 rd drums for their FFs). WIth MG FFM, I'd go exclusively with M-shells - dissimilar trajectory is a shortcoming, so is the enemy pilot being alerted with tracers.



> My German is practically non existent. In the early part of that manual is some reference to 650kph but I don't what it refers to.
> 
> Blatt 4 (?) near the end of the first paragraph?



'Gleit' will be 'glide' - so it's about as close to permissible dive speed as possible for a big aircraft without dive brakes?




> BTW the manual shows some rather strange drawings of a Zerstorer near the end. it appears to have a single cannon firing through each prop hub and no other changes to armament.
> Unsold proposal? Magazines under the gun? notes seem to indicate Oerlikon FFS guns which used the same ammo as Allied AA guns (very comparable to the Hispano.
> Export to Sweden?



All correct, although Sweden never got any DO 215s.
Dornier was trying hard to find a new lease of life for the Do 17 line 



Kevin J said:


> Like but disagree:-
> Mig-3. No change. Discarded as unsuccessful design for Eastern Front.
> Sea Hurricane I from 1939 for service on carriers not Sea Gladiator. No folding wings ever as interim type pending arrival of Seafire. Sea Hurricane Ib (1939), IIb (1940), IIc (1941). Replaced by Seafire in 1942.
> Spitfire III to form basis for Seafire to be put into production by Westland in 1941. Maybe Seafire Ic (c for carrier version) not Spitfire I's in 1941 for training, hook only and Merlin 20. Seafire IIc as per Spitfire III without folding wings in 1942 with late Merlin 20 series, but with hook and catapult spools. Seafire LIII as per Spitfire III with folding wings service intro early 1943 using Merlin 32, first deliveries late 1942. Cunliffe Owen to build Seafire XV based on Spitfire IV with Griffon engine service intro 1943, limited edition. Seafire FR 17 to appear in 1944. Should all be feasible. Supermarine leads the way for land based versions with Castle Bromwich being the mass producer. Westland uses their design skills to turn the Spitfire III/IV into World beating carrier fighters.
> ...



I know that MiG-3 was not a great success. My proposal rectifies lack of firepower (there was a hostorical small series of MiG-3s with two cannons, so nothing ground-breaking there), lack of engine power under 3-4 km (where it was actually needed; such MiG-3 was tested, achieved 600 km/h) and propensity for pilots to fly with open canopies (that robbed the speed).
Zero and Oscar with better motors only from 1943 means that Japan has still lost not just battles, carriers, aircraft and men, but also pilots to fly them.


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## Kevin J (Jun 3, 2019)

tomo pauk said:


> I know that MiG-3 was not a great success. My proposal rectifies lack of firepower (there was a hostorical small series of MiG-3s with two cannons, so nothing ground-breaking there), lack of engine power under 3-4 km (where it was actually needed; such MiG-3 was tested, achieved 600 km/h) and propensity for pilots to fly with open canopies (that robbed the speed).
> Zero and Oscar with better motors only from 1943 means that Japan has still lost not just battles, carriers, aircraft and men, but also pilots to fly them.


Bigger engines, same fighter means less range. Even the F4F-3 Wildcat was delivered without self sealing fuel tanks. It was all about range. I'm suggesting 1943 because clearly that's the point where the Jap Empire has expanded to its max extent. You need a defensive mentality after that, aircraft too.


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## tomo pauk (Jun 3, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> I guess the our "What-If" conditions are just a bit different. I was thinking minimal adjustments to the industry and fairly small changes in the existing environment while it seems like you were thinking of much larger series of cascading changes and management direction.



Think big 



> I had forgotten that the changes to the Allison engine series was mostly just a change in supercharger gear ratios.
> 
> - Ivan.



Not just that. Change in type of reduction gear type meant increased reliability at higher powers, improvements in carankcase and crankshaft were also crucial in passing WER tests more reliably (so the engine can be rated for higher power by the user), there was improvement in valve gear in 1940/41 so the engine can actually make listed HP etc. We also have 2-stage supercharged versions, thata) came a bit too late, and b) were installed in aircraft irrelevant to the ww2. Water injection was also a plus, but again only for 2-stage versions.


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## tomo pauk (Jun 3, 2019)

Kevin J said:


> Bigger engines, same fighter means less range. Even the F4F-3 Wildcat was delivered without self sealing fuel tanks. It was all about range. I'm suggesting 1943 because clearly that's the point where the Jap Empire has expanded to its max extent. You need a defensive mentality after that, aircraft too.



Delivery of F4F-3s without self sealing tank was a bug, not a feature. 
Bigger engines = bigger payload (fuel included) + less drop in performance once you start adding protection. Better performing aircraft can meant the difference between carrier being sunk and the one afloat, they are a better asset both in offense and defense. 
Defensive mentality does not work after you've lost bulk of your trained & experienced armed forces, and enemy is out-producing you 5:1 or better.

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## pinsog (Jun 3, 2019)

Why not a turbocharged F4F-3? No magical time line, just using what we already have. Bugs won't get worked out of turbocharger until early 1942, but plane should perform awesome. Wish I could calculate increase in climb. 

Original 2 speed 2 stage P&W R-1830-76:
1200 hp for takeoff
1100 hp from SL-2500 feet
1050 hp from 4800-11000 feet
1000 hp from 12200-19000 feet

with a P&W R-1830-47 with a turbocharger (same engine as the P43 Lancer)
1200 hp from SL-25000 feet, still producing 1,000 hp at 30,000 feet.

SL speed increases from 278 to 286
Speed at 5500 goes from 295 to 308
Speed at 13000 goes from 313 to 332
Speed at 19000 goes from 330 to 350
Speed at 22000 goes from 326 to 351

The F4F-3 speed numbers above included 150 pounds of armor and a self sealing fuel tank.

P&W 1830 or Wright 1820 uses lowest geared supercharger so less power to turn supercharger. Turbocharger is only used as air begins to thin out so at low altitude, SL-2500 or so, turbocharger isn't even being used, flap to intercooler remains completely closed. As F4F-3 gains altitude, flap to intercooler is only opened enough as needed, cutting down on drag. Engine needs less power to run supercharger allowing more power to turn prop, meaning less boost from turbocharger, meaning less heat, meaning less use of intercooler, meaning less drag. (At least that is the way it works in my head)

Drop tanks from day 1


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## pinsog (Jun 3, 2019)

The other plan I actually prefer is ditch the F4F-3 all together and tell Grumman to develop the XF5F Skyrocket. Original plan was for long nose and long nacelles, then they went to short nose (lower stall speed, super gentle and predictable stall) and short nacelles (no reason that I know of). Long nose and long nacelles added 15-18 mph top speed. For carrier work I would build long nacelles and a short nose, giving added top speed from the nacelles but slower stall for carrier work of the short nose.

Weight of original came in at 10,892 in overload with 278 gallons of fuel, radio installed and apparently ballasted for 4 50's and 400 rpg. I would redesign the center section between the engines for a self sealing tank (apparently the original had some internal bracing that made it difficult or impossible for self sealing liner to be added), add armor and add turbochargers to give engine 1200 hp apiece from SL-25,000 feet.

10,900 pounds with 278 gallons of fuel, 4 50's and 400 rpg, add 200 pounds for self sealing tank (Corsair had 177 pounds of self sealing material for 237 gallons) add 150 pounds for armor and 500 pounds for turbochargers.

Total weight: 11,750 with 2,400 hp from SL-25,000 feet.

original on 2000 hp SL 312 mph turbocharged 2400 hp 331 mph
original on 2000 hp at 4500 ft 326 mph turbocharged 2400 hp 346 mph
original on 1800 hp at 7300 ft 324 mph turbocharged 2400 hp 356 mph
original on 1800 hp at 14000ft 346 mph turbocharged 2400 hp 380 mph
original on 1500 hp? 20000ft 352 mph turbocharged 2400 hp 411 mph
original on 1000 hp? 30000ft 315 mph turbocharged 2000 hp 397 mph

I would also have added tanks in the outer wing panels like a Corsair (64 unprotected but purged by CO2) or P38 (55 gallon protected)

Adding about 650-700 pounds of weight in fuel, no idea what the unprotected 64 gallon tanks would weigh empty or what 55 gallon protected tanks would weigh empty.

Climb should be phenomenal considering it has an extra 100 hp over early P38 and weighs about 3000 pounds less without the wing tanks and probably about 2000 pounds less if the wing tanks are full giving it around 400 gallons of fuel without drop tanks.

If Grumman dropped the Wildcat, the F5F should be on about the same timeline

Essentially, we have a plane with early P38 speed performance, should have significantly higher climb performance, exceptional weight lifting performance and docile to land on a carrier with 2 counter rotating engines

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## Shortround6 (Jun 3, 2019)

pinsog said:


> Why not a turbocharged F4F-3? No magical time line, just using what we already have. Bugs won't get worked out of turbocharger until early 1942, but plane should perform awesome. Wish I could calculate increase in climb.
> 
> Original 2 speed 2 stage P&W R-1830-76:
> 1200 hp for takeoff
> ...



Ir works just fine until you get into the high teens at which point the existing intercoolers are too small. 
We have been over this in some thread in just the last few weeks. 
On the F4F all the supercharger plumbing/ducts are forward of the wheel wells.

the landing gear works like this.











From VC-27 "The Saints" - Aircraft 
On the F4F the intercoolers are just forward of the wheel wells and in fact the used cooling air form the intercoolers is dumped into the wheel wells to find its way out of the plane. 

You have the fuel tanks in the center of the plane under the cockpit and behind it.


The P-43 landing gear was in the wing and when retracted left space for the exhaust pipe duct in the bottom of the fuselage. The P-43 also used a fuel tank in each wing which left the fuselage clear.

In the low 20,000ft range you need bigger intercoolers because you are trying to compress the air more (more heat) but the ambient air is thinner (less pounds per cubic ft)) so you need a larger airflow to even cool the same amount of combustion air. 

Maybe you can do it. It just isn't going to be simple. TANSTAAFL


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## pinsog (Jun 3, 2019)

Shortround6 said:


> Ir works just fine until you get into the high teens at which point the existing intercoolers are too small.
> We have been over this in some thread in just the last few weeks.
> On the F4F all the supercharger plumbing/ducts are forward of the wheel wells.
> 
> ...



They would have to do it early on. Looks like there is room to slide a couple of (what diameter exhaust pipe? What diameter pipe from turbo to engine? 5 inch? 6 inch?) pipes through there. I don't think the fuel tank would be an issue, after the landing gear the 2 pipes just run along the floor with the bottom of the tank adjusted to let them pass through (easy if done from the beginning of course)

Agree that at upper altitude you would need a larger intercooler, (move intercooler to back near turbo?) but you would not need to use the larger capacity of the larger intercooler until you get to that altitude so you wouldn't be increasing drag, you only open the flap to the intercooler enough to cool the air at the altitude you are at. At low altitude the turbo is not doing anything so the intercooler flap would be completely closed, correct?

How much HP does high gear on a P&W 1830 use? if you are turning a lower gear on the supercharger, you aren't losing that hp to turn the higher gear because of the turbocharger, so the engine is either working less to put the same hp to the prop, or working the same to put more hp to the prop, correct?


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## Shortround6 (Jun 3, 2019)

Actual pictures are better than drawings

F4F through the wheel wells.

Grumman F4F-3 Wildcat Museum of Naval Aviation Photo Walk Around Image 08


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## pinsog (Jun 3, 2019)

I would move that intercooler to the back near the turbo and make it larger. 

Like I said, they would need to tackle this early on. Love to see a head on pic with the engine removed. I think the landing gear would be the biggest headache. I don't think the fuel tank would be a big issue. Just adjust the bottom of the tank with the pipes installed.


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## pinsog (Jun 3, 2019)



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## pinsog (Jun 3, 2019)

If you have room for windows to look out the bottom of the plane, you might have room for some plumbing to and from a turbocharger. Move the intercoolers to the back by the turbo and then see if you can slip the two pipes from the collector ring through the landing gear. The landing gear looks like it will be a pain. Much easier to do this BEFORE you build the entire plane!


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## Shortround6 (Jun 3, 2019)

One problem is the lower photo in post #145 is of an FM-2 which used a 9 cylinder wright R-1820 engine with a single stage supercharger, Firewall/engine compartment details are somewhat off from a F4F-3/4 like the first photo.

Please look at the link, the photos are way too big to post here. There are a number of other things either sticking back into the landing gear bay or routed through it. 

Any piping (exhaust or intake air or???) is going have to use radiused bends. Too sharp a bend and you you loose pressure, either pressure in the exhaust or pressure from the turbo to the carb on the engine supercharger. 

As far as figuring power goes, General motors put out a booklet during WW II comparing 7 different supercharger systems.




It may be available for download? They used a hypothetical 1000hp engine to illustrate the differences. 
GM owned Allison, a coincidence??? 

In any case turbo superchargers are not "free" HP. If you could supply the theoretical 1000hp engine with sea level air pressure to the carb at 20,000ft the engine would amke about 1080hp due to the reduced back pressure on the exhaust pipes/ports. 
You do free up more than 80 hp by eliminating the 2nd gear driven supercharger. 

Part of the reason that the P-43 made 1200hp at the higher altitudes is that it was rated at 2700rpm while the 2 stage engine, except for take-off, is rated at 2550rpm. I have never found the reason for this. A pilots manual even has a section that states the two stage engine could use 2800rpm for emergency take-off (shortened the take off run by 60 or 80 ft?) but permission to use that RPM for emergency climb had been rescinded. 

Another problem is the propeller. Wildcats used a 9'9" or 10ft prop. the P-43 used an 11ft prop. You can't use a prop designed to transmit 900hp or so at altitude to transmit 1200hp. 
The problem comes in when the Wildcat is flying level on the runway or deck. In "static" conditions the Wildcat has 8.75in of clearance for the prop. The 11ft P-43 prop would cut that to 2.75 in and the Wildcat had some of the "spongest" landing gear going. Deflection from the static line upwards could 5 1/4 inches. Overall oleo defection was 12 1/2 inches. 
Perhaps you could fit an in between prop and risk the prop strikes (nobody was using broad cord baldes in 1941/42) but your climb and speed might be a bit off the estimates with a less efficient propeller. 
If you try computing speeds using the FM-2 it does get some help from exhaust thrust.

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## pinsog (Jun 3, 2019)

Good information Shortround. If they had done this, obviously the intercoolers would be out of the way and they would have to move some of the things around that are right now, bolted to the landing gear mounts, and also agree that the fewer bends the better which is why they would need to do this early on. I also know that there were bugs in the turbocharger controls until early 1942. 

On the prop, as you know, it would be a matter of them choosing the best prop that covers the most area they expect to be fighting in with the best average of climb, speed at the altitude they expect to fight at etc with no prop being best at everything. Obviously for a carrier based fighter, 25,000 feet would probably not be very high on the priority list, but top speed from SL-20,000 and climb rate would, i imagine, be what they focus on. 

They would have to test several props to see what was best. But, prop doesn't mean much if you don't have the power to turn it. 

Just curious, could you get away with the stock intercoolers if you stayed between SL and 20,000 feet? Again, my thinking is, your running the lowest geared supercharger so you don't have the parasitic loss of turning high gear on the 2 speed, the turbocharger then making up the difference. (I know turbochargers aren't totally free power, but they cost a lot less power than spinning a supercharger)


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## tomo pauk (Jun 6, 2019)

To circumvent a bit powerplant-related issues of the F4F - how about Grumman (or anyone capable) makes a fighter where the widest part of fuselage is at engine cylinders, not at half of length? Couple that with a smaller wing (say, 220 sq ft?) that has Fowler flaps installed, and both drag and weight should be a bit trimmed down, for better speed & climb?

Similar for the Japanese - Zero with wing of 200 sq ft (instead of 240 sq ft) with Fowler flaps. Thus even with Sakae it can prove a better match for improved Allied aircraft of late 1942 on. With shorter wing it should also roll better.

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## pinsog (Jun 6, 2019)

tomo pauk said:


> To circumvent a bit powerplant-related issues of the F4F - how about Grumman (or anyone capable) makes a fighter where the widest part of fuselage is at engine cylinders, not at half of length? Couple that with a smaller wing (say, 220 sq ft?) that has Fowler flaps installed, and both drag and weight should be a bit trimmed down, for better speed & climb?
> 
> Similar for the Japanese - Zero with wing of 200 sq ft (instead of 240 sq ft) with Fowler flaps. Thus even with Sakae it can prove a better match for improved Allied aircraft of late 1942 on. With shorter wing it should also roll better.



Hmmmm. Like maybe a P43 with a skinnier body? (And fuel tanks that don’t leak...)

A P43 with the body of a Skyrocket and fuel tanks that don’t leak?

I don’t think the turbocharged F4F-3 would be difficult to do as long as it is done early in the design. Retrofitting in 1941 after production was started will obviously be much more difficult

Edit: I can read Shortrounds mind right now “if you have a skinny little fuselage and a tiny wing, where does the fuel go? Where do weapons and ammo go? What will the range be? What will climb rate be with a small wing?
(Did I guess right Shortround? Hope so because it’s what im thinking as well)

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## tomo pauk (Jun 6, 2019)

pinsog said:


> Hmmmm. Like maybe a P43 with a skinnier body? (And fuel tanks that don’t leak...)
> 
> A P43 with the body of a Skyrocket and fuel tanks that don’t leak?



I was thinking about something like P-36.



> I don’t think the turbocharged F4F-3 would be difficult to do as long as it is done early in the design. Retrofitting in 1941 after production was started will obviously be much more difficult



Yes, if the aircraft was designed for turbo from the get-go, then turbo might be a workable solution. The historical F4F might've had one of better radials of 1941, but it was a portly aircraft, with a big wing - meaning a lot of drag and weight.


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## Shortround6 (Jun 6, 2019)

tomo pauk said:


> To circumvent a bit powerplant-related issues of the F4F - how about Grumman (or anyone capable) makes a fighter where the widest part of fuselage is at engine cylinders, not at half of length? Couple that with a smaller wing (say, 220 sq ft?) that has Fowler flaps installed, and both drag and weight should be a bit trimmed down, for better speed & climb?
> 
> Similar for the Japanese - Zero with wing of 200 sq ft (instead of 240 sq ft) with Fowler flaps. Thus even with Sakae it can prove a better match for improved Allied aircraft of late 1942 on. With shorter wing it should also roll better.


 Granted they used different wings but the P-36/Hawk 75 had it's greatest fuselage diameter at the engine cowl. You can check performance at the lower altitudes where power was similar to see any difference. While the "fat/wide" fuselage F4F may have been at a disadvantage the "fat/tall" F4F gave bit better view for landing and allowed for a greater angle for deflection shooting over the nose. F4F was also trying to hide the main wheels in the fuselage. Make the fuselage too skinny and the wheels are not going to fit the circumference of the fuselage as well. 

Be careful about clipping wings. The aspect ratio affected the efficiency of the wing. A high aspect ratio wing actually gets more "lift" per sq ft of area or perhaps more lift per unit of drag. Perhaps not important for a short range fighter but rather important for a long range fighter like the Zero. Forcing it to cruise faster to get the same "lift" (especially with the smaller wing) may cut the range. Please look at the Spitfire for a good illustration of this. The actual changes to square footage of area were tiny. The extended wing version was 2.6 % bigger and while it did hurt a few aspects of the performance, especially at low altitudes, it helped with others at high altitude. the Clipped wing version was 95.4% as big as the standard wing. 
The aspect ratio was a much bigger change. 

roll response seems to have something to do with how far the wing extended beyond the end of the Ailerons. In general planes with ailerons that were 'recessed" away from the tips seem to have worse response than ones with ailerons going to the tip (or having the tip cut back to the end of the aileron.) A short wing does not automatically give good roll response unless the aileron is sized in proportion to the wing and has enough deflection (failing of the early Mustangs?) A short wing only has so much trailing edge and you have a conflict going with either large enough flaps to get the landing speed you want or large enough ailerons to get the roll response you want. Drooping ailerons can help but are an added complication.


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## pinsog (Jun 6, 2019)

I like the P36 Tomo. I think it would have gained a lot of speed just from cleaning up the wing by redesigning the landing gear and adding at least a 2 speed engine. But we’ve done so many “better P36” and when we add a 2 stage engine and X many 50’s with ammo it starts getting pretty heavy.

At least with an F4F-3 we have armor, self sealing tanks, 4 50’s, 450 rpg, good amount of fuel and a heavier 2 stage engine. All we need to do is exchange the 2 speed 2 stage engine with a turbo and we get 1200 hp from SL-25000 feet (they would have to test it and pick the prop that works best for the job). And add drop tanks. 

If you check my numbers on increased performance I think it would be a winner.


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## Shortround6 (Jun 6, 2019)

The F4F was also designed to meet pre war limits on landing and take-off speeds/distances on Carriers. relax those standards even 10% and there is a lot you can do. If the standards are not relaxed/waived then you are stuck with the large wing.


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## pinsog (Jun 6, 2019)

Tomo, if you are specifically talking about a carrier fighter, I don’t think you can reduce the wing size. Between landing speed, controllability, and lifting off a carrier with a full load of fuel and drop tanks I just don’t think you can go any smaller on the wing


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## Kevin J (Jun 6, 2019)

tomo pauk said:


> To circumvent a bit powerplant-related issues of the F4F - how about Grumman (or anyone capable) makes a fighter where the widest part of fuselage is at engine cylinders, not at half of length? Couple that with a smaller wing (say, 220 sq ft?) that has Fowler flaps installed, and both drag and weight should be a bit trimmed down, for better speed & climb?
> 
> Similar for the Japanese - Zero with wing of 200 sq ft (instead of 240 sq ft) with Fowler flaps. Thus even with Sakae it can prove a better match for improved Allied aircraft of late 1942 on. With shorter wing it should also roll better.


You mean Airacobra sized wing so although it goes faster, its higher stalling speed means that its altitude performance is worse.


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## tomo pauk (Jun 6, 2019)

pinsog said:


> Tomo, if you are specifically talking about a carrier fighter, I don’t think you can reduce the wing size. Between landing speed, controllability, and lifting off a carrier with a full load of fuel and drop tanks I just don’t think you can go any smaller on the wing





Shortround6 said:


> The F4F was also designed to meet pre war limits on landing and take-off speeds/distances on Carriers. relax those standards even 10% and there is a lot you can do. If the standards are not relaxed/waived then you are stuck with the large wing.





Kevin J said:


> You mean Airacobra sized wing so although it goes faster, its higher stalling speed means that its altitude performance is worse.



I've specified Fowler flaps for both types.

BTW, regarding the post #156 here: Airacobra's altitude performance was a result of the V-1710 making a sub-par power at higher altitudes in 1941-late 1942, combined with customer's requirement that it must carry 900 lbs worth of guns & ammo.


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## tomo pauk (Jun 6, 2019)

Shortround6 said:


> ...
> Well, the Do 215 was rated at just about 500kph. Since the bombs are carried inside it doesn't take the performance hit that strapping bombs to the bottom of the 110 would cause so the actual attack speeds (30 minute rating?) would be a lot closer. Get rid of the "bug-eye" nose and put on something like the night fighter nose. Use DB 601N or E engines (mainly to get the altitude up higher than the DB601A and DB601Aa. You also have a more range than the 110. Possibility of trading bomb bay space for more fuel. Just do something about the idiotic gun array at the rear of the canopy.
> 
> It will never equal the Mosquito but since you could have them almost 2 years before the Mosquito shows up in any numbers it doesn't have to be quite as good.
> The JU-88 was never going to equal the Mosquito either as by the time you get to the A-4 (very late 1940/early 41) you have plane weighing thousands of pounds more.



To return for a moment to think about the Do 215 and alternatives. If we agree that dive bombing is not required, and that 50 kg bombs are okay, the Ju 88A-1/A-4/A-5 can lose dive brakes and bomb racks - that will give another 15-20 km/h? The A-1's internal bomb racks were carrying 18 x 50 kg bombs in front chamber, plus 10 bombs in aft chamber - that is 28 vs. possible 20 on the Do17/215.


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## Shortround6 (Jun 6, 2019)

tomo pauk said:


> To return for a moment to think about the Do 215 and alternatives. If we agree that dive bombing is not required, and that 50 kg bombs are okay, the Ju 88A-1/A-4/A-5 can lose dive brakes and bomb racks - that will give another 15-20 km/h? The A-1's internal bomb racks were carrying 18 x 50 kg bombs in front chamber, plus 10 bombs in aft chamber - that is 28 vs. possible 20 on the Do17/215.


True but the Ju-88 A-4 used engines that had 1340hp for take-off and gave 1060hp at 17,000ft (?? old source, open to correction)
while the Do-215 used DB 601Aa engines that gave 1175ps (1 minute) for take off and 1100ps at 12,210ft. (5 minute).
The Do-215 was being phased out before the Ju-99A-4 really entered production due to delays in the Jumo 211J engine.
The Ju-88 carried 369 Imp gallons of fuel without resorting to bomb bay tanks and the Do-215 carried 341 imp gallons in the wing root tanks without resorting to bombay tanks.

AN "improved" DO 215 might well operate at somewhat higher gross weights than the Do-215 (7000-8500kg) and put a bit more fuel in the wings?

The Ju-88A-4 was an "improved" Ju-88A-1 with a bigger. stronger wing, more powerful engines, beefed up landing gear and a few other changes that that raised the empty equipped weight by over 2000kg..

Trying to modify the Do-215 to _equal _the Ju-88A-4 in load carrying ability is a losing game. You need a whole new airplane. But using the Do-215 as a starting point for a high speed (330mph ?) bomber that could carry four 250kg bombs at a high cruising speed might have promise.
Given the chronic shortage of DB engines it is not realistic and that engine shortage is the main stumbling block.


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## Shortround6 (Jun 6, 2019)

Trying to make a better carrier plane than the F4F is going to take a bit of doing. 
Using the stock flaps reduces the take-off run by about 25%. At 7921lbs it is supposed to take just under 700ft to take off in zero wind using the flaps. 
Stalling speed with 4 guns clean was supposed to be 69 knots power off, Power on reduced that to 63kts. with flaps and gear down the stalling speed dropped about 9 knots or more. 
Flaps had one setting (43 degrees)and were vacuum operated, as speed built up over 130knots the flaps "blew up" until about 10 degrees meaning the pilot could pretty much ignore them while taking off (a good thing as he had to crank the landing gear up by hand.)
Using a small wing and trick flaps may not actually get you much. 

I would also note that the figures for the P-43 at 6913lbs (about 1000lbs lighter) call for a ground run of 1070ft using 15 degrees of flap. 
P-43 at weight has no armor, no self sealing tanks. 145 US gallons and 250.6 pounds of armament ( four .50s with no ammo weigh around 300lbs)
P-36C needed 600ft with 30 degrees of flap at a weight of 5800lbs (another 1000lbs lighter) and held 105 us gallons, 292lbs of guns and ammo, no armor, no self sealing tanks. and had trouble with the wing skin wrinkling or buckling in the area of the landing gear attachments.

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## pinsog (Jun 7, 2019)

I would have to agree with you. When I suggested a skinnier P43 I thought it was for a better land based fighter. I don’t think you can do with a smaller wing for a carrier based fighter.


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## tomo pauk (Jun 7, 2019)

Shortround6 said:


> True but the Ju-88 A-4 used engines that had 1340hp for take-off and gave 1060hp at 17,000ft (?? old source, open to correction)
> while the Do-215 used DB 601Aa engines that gave 1175ps (1 minute) for take off and 1100ps at 12,210ft. (5 minute).
> The Do-215 was being phased out before the Ju-99A-4 really entered production due to delays in the Jumo 211J engine.
> The Ju-88 carried 369 Imp gallons of fuel without resorting to bomb bay tanks and the Do-215 carried 341 imp gallons in the wing root tanks without resorting to bombay tanks.
> ...



The Ju 88A-1 was rated for 28 x 50 kg bombs, and was available in 1940 for the BoF (in small numbers) and for the BoB (in better numbers). Initially started with two Jumo 211A engines (1100 PS for take off), then switched to 1200 HP 211s.
Ju 88 line can also be fast bomber - no racks, no dive brakes, thin cockpit, better engines than it was around in 1940 etc.



pinsog said:


> I would have to agree with you. When I suggested a skinnier P43 I thought it was for a better land based fighter. I don’t think you can do with a smaller wing for a carrier based fighter.



Well, neither Zero nor WIldcat carried anything from the high-lift devices. Known to the pople all around the world by mid-1930s, Fowler flaps were used on Lockheed aircraft, as well as (as a derivative) on the Ki-43. Slats were also around.

To move a bit from the Pacific Dynamic Duo.
- Hawker Fury: designed as a monoplane
- Gloster Gladiator: ditto; Mk.2 with retractable U/C
- A-S Whitley: designed as a 4-engined bomber
- Avro Lancaster: designed with less guns, more streamlining
- Ju 88: designed with shoulder/high wing, so it can have a meaningful bomb bay
- Gloster F.5/34: designed around Hercules
- MB.2: designed around Merlin, with retractable U/C


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## Kevin J (Jun 7, 2019)

Shortround6 said:


> Trying to make a better carrier plane than the F4F is going to take a bit of doing.
> Using the stock flaps reduces the take-off run by about 25%. At 7921lbs it is supposed to take just under 700ft to take off in zero wind using the flaps.
> Stalling speed with 4 guns clean was supposed to be 69 knots power off, Power on reduced that to 63kts. with flaps and gear down the stalling speed dropped about 9 knots or more.
> Flaps had one setting (43 degrees)and were vacuum operated, as speed built up over 130knots the flaps "blew up" until about 10 degrees meaning the pilot could pretty much ignore them while taking off (a good thing as he had to crank the landing gear up by hand.)
> ...



Of course you could always take a standard Spitfire I/II of 1939/40, add folding wings, catapult spools, arrestor hook, naval radio etc. Now that should knock a good 20 mph off its top speed, so say 335 mph. Looks like its not going to be any faster than a Wildcat but much more fragile. So what would everyone prefer in 1940/41 a Seafire or a Wildcat? I'd go for the Wildcat. 

As an interim measure, you could sling a hook underneath a Hurricane, add individual exhausts and you should not lose any speed, but at altitude is there any significant performance difference between that and a Wildcat? No there isn't. At low altitude where the performance is needed, the Sea Hurricane is much faster with first 12 then 16 lbs of boost, but you can only operate them in a deck park and on outriggers. Alternately why not use water injection on the Wildcat engine to boost low altitude speed? Then the Wildcat would show itself to be superior to the Sea Hurricane.


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## wuzak (Jun 7, 2019)

Kevin J said:


> Of course you could always take a standard Spitfire I/II of 1939/40, add folding wings, catapult spools, arrestor hook, naval radio etc. Now that should knock a good 20 mph off its top speed, so say 335 mph. Looks like its not going to be any faster than a Wildcat but much more fragile. So what would everyone prefer in 1940/41 a Seafire or a Wildcat? I'd go for the Wildcat.
> 
> As an interim measure, you could sling a hook underneath a Hurricane, add individual exhausts and you should not lose any speed, but at altitude is there any significant performance difference between that and a Wildcat? No there isn't. At low altitude where the performance is needed, the Sea Hurricane is much faster with first 12 then 16 lbs of boost, but you can only operate them in a deck park and on outriggers. Alternately why not use water injection on the Wildcat engine to boost low altitude speed? Then the Wildcat would show itself to be superior to the Sea Hurricane.



Why not just put a hook on the Spitfire, like you did for the Hurricane, which should allow it to retain its performance, like you suggest for the Hurricane?

The Spitfire I is good for 355-360mph at best altitude, with 2 x 20mm cannon. You could improve that by adding individual exhaust stacks, like you suggest for the Hurricane.

The Spitfire is smaller than the Hurricane, both retaining fixed wings. It is smaller in length, wing span and height.

It's also lighter, so the supposed fragility has to deal with lower loads than the Hurricane. Or F4F.

As to your first question, in 1940 I'd definitely go for the Seafire, or at least a Spitfire I with arrestor hook. In 1940 the Spitfire I has the significant advantage over the F4F of actually being available.

For 1941 we might put those Merlin XXs that would have otherwise gone into Sea Hurricane IIs, further improving the Spitfire's performance. Plus you have the additional 20mm cannon firepower.

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## Kevin J (Jun 7, 2019)

wuzak said:


> Why not just put a hook on the Spitfire, like you did for the Hurricane, which should allow it to retain its performance, like you suggest for the Hurricane?
> 
> The Spitfire I is good for 355-360mph at best altitude, with 2 x 20mm cannon. You could improve that by adding individual exhaust stacks, like you suggest for the Hurricane.
> 
> ...



You're crazy. The Spitfire I/II/Vb would never have worked well over the Atlantic and Arctic. I mean, where did we use it first, in the calmer waters of the Mediterranean, and we still lost lots of them. Now me, I would have used the Spitfire III as the basis for the Seafire. So Westland could have perhaps produced its first batch of 50 for training purposes in 1941 rather than the Spitfire I's they actually produced. So Seafire I with Merlin VIII, hook only 1941. Seafire II with Merlin XXX, hook plus catapult spools, 1942. Seafire III using Merlin 32, hook, catapult spools, folding wings, 1943. That would bring its service intro forward a whole year.


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## Ivan1GFP (Jun 7, 2019)

tomo pauk said:


> To circumvent a bit powerplant-related issues of the F4F - how about Grumman (or anyone capable) makes a fighter where the widest part of fuselage is at engine cylinders, not at half of length? Couple that with a smaller wing (say, 220 sq ft?) that has Fowler flaps installed, and both drag and weight should be a bit trimmed down, for better speed & climb?
> 
> Similar for the Japanese - Zero with wing of 200 sq ft (instead of 240 sq ft) with Fowler flaps. Thus even with Sakae it can prove a better match for improved Allied aircraft of late 1942 on. With shorter wing it should also roll better.



Hello Tomo Pauk,
It sounds to me like the CW-21 would fit your requirements for an ideal fighter if it had a bit more engine power.
The problem with Fowler flaps is that they really aren't magical. You are going to need more equipment and structure to make that work.

The A6M actually had a pretty high roll rate. It just didn't have a high roll rate at high speed. It wasn't a matter of wing area or wing span that reduced its roll rate at high speed.
The problem with reducing the wing area down to 200 ft^2 is that it would take a serious range hit and lose maneuverability.
Note that the A6M3-32 Hamp had a clipped wing down to only about 230 ft^2 and even that small reduction proved to be not so useful to the point where only a few hundred were produced.

Note also that the Ki 43 Hayabusa had a pretty similar sized wing to the A6M series and did not suffer the same reduction in roll rate at high speeds.
As I see it, the Sakae series of engines was a nicely refined and reliable design, but it was pretty much a dead end for development.
The power improvement with the Type 0 Mk.II series of fighters wasn't enough to offset the weight increases over the Mk.I (A6M2) to the point where the earlier fighter was considered better at low and medium altitudes.



tomo pauk said:


> Think big



Kill Goering very early.

- Ivan.


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## Shortround6 (Jun 7, 2019)

Kevin J said:


> You're crazy. The Spitfire I/II/Vb would never have worked well over the Atlantic and Arctic. I mean, where did we use it first, in the calmer waters of the Mediterranean, and we still lost lots of them.


 And counter intuitively, it was those calm waters with their lack of wind and high temperatures that caused the problems. Together with operating off of escort carriers with small decks and a distinct lack of speed to make up for the zero wind. 
Please note that the US made no attempt to *operate* their _army_ fighters off carriers. They flew them off* once* lightly loaded to land ashore. At Salerno the US was able to P-38s based in NA to cover the invasion. 

The early Seafires still needed beefing up but the losses would have been much reduced had the temperature been even 10 degrees C colder and a somewhat steady 8-12 knot wind for most of the day. Or carriers that went faster, of the five British carriers at Salerno one went 24 kts, the other 4 did 18kts tops.

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## Shortround6 (Jun 7, 2019)

tomo pauk said:


> - Hawker Fury: designed as a monoplane


Perhaps but you are going to wind up with something that looks like P-26 or Dewoitine D.510 





and perfectly useless for combat in 1939. 



tomo pauk said:


> - Gloster Gladiator: ditto; Mk.2 with retractable U/C



Licence Curtiss Hawk III ?






tomo pauk said:


> A-S Whitley: designed as a 4-engined bomber



Using what for engines? And any four engine machine may have been too large and too expensive for the ministry to contemplate at that time. 
A 4 engine bomber using the airfoil of the Whitley would make the Sterling look like a speed demon 



tomo pauk said:


> Avro Lancaster: designed with less guns, more streamlining


You have to start back with the Manchester, once you are stuck with the Manchester fuselage no amount of plating over openings or putting fairings on the nose and tail it going to get you enough speed to really change things. 



tomo pauk said:


> - Gloster F.5/34: designed around Hercules



Another candidate for R-1830 or R-2600 engines when the early Hercules turns into a problem child with early production problems. 
early Hercules III was good for about 1250hp at 15,500ft and the drag of an early Hercules engine nacelle/installation is going to kill any HP advantage over an early Merlin. 
With a bigger prop, the much heavier engine and new landing gear you are pretty much designing a new airplane. 



tomo pauk said:


> - MB.2: designed around Merlin, with retractable U/C


another plane that is going to need extensive rework to turn into an operational fighter. 




This is with the 3rd tail fin and rudder and it is going to be too small for a Merlin.


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## fliger747 (Jun 7, 2019)

Perhaps the best change that can be made to a satisfactory existing design is to "Simplicate and add lightness" via careful detail design. Heinemann attributes the success of His A4 to this, careful design of everything. The FM2 was a successful upgrade to the F4F without using too much new technology. However the "Zero" already had good detail design, which unfortunately left little room for "improvement".


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## tomo pauk (Jun 7, 2019)

Shortround6 said:


> Perhaps but you are going to wind up with something that looks like P-26 or Dewoitine D.510
> and perfectly useless for combat in 1939.



Monoplane Fury gives experience to Hawker in designing, well, monoplanes. So we might have a less conservative Hurricane, and better performing Typhoon from day one.



> Licence Curtiss Hawk III ?



I was not crystal clear - 'ditto' was supposed to mean 'also monoplane' for the Gladiator.



> Using what for engines? And any four engine machine may have been too large and too expensive for the ministry to contemplate at that time.
> A 4 engine bomber using the airfoil of the Whitley would make the Sterling look like a speed demon



4-engined bomber is not lost in case of engine-out, so the AM might see the point there (though I don't hold my breath that they will).
Engines - prototype might as well use the A-S Tiger (yes, I know that it was not a very good engine), then switch to Pegasus. 
For real-world example, please see: A-W Ensign (switched from Tigers to Cyclones). Together with DH Albatros, it indeed looked like speed demon vs. British multi-engines aricraft of the time,



> You have to start back with the Manchester, once you are stuck with the Manchester fuselage no amount of plating over openings or putting fairings on the nose and tail it going to get you enough speed to really change things.



Yes, start early for the gain. OTOH, even getting rid of top and nose turrets and streamlining the nose would've meant that German NFs have a shrunken window of opportunity for shotdown.



> Another candidate for R-1830 or R-2600 engines when the early Hercules turns into a problem child with early production problems.
> early Hercules III was good for about 1250hp at 15,500ft and the drag of an early Hercules engine nacelle/installation is going to kill any HP advantage over an early Merlin.
> With a bigger prop, the much heavier engine and new landing gear you are pretty much designing a new airplane.



A new airplane indeed.




> another plane that is going to need extensive rework to turn into an operational fighter.
> This is with the 3rd tail fin and rudder and it is going to be too small for a Merlin.



Yes, start with Merlin from the get-go.


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## tomo pauk (Jun 7, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> It sounds to me like the CW-21 would fit your requirements for an ideal fighter if it had a bit more engine power.
> The problem with Fowler flaps is that they really aren't magical. You are going to need more equipment and structure to make that work.



CW 21 have had it's good points, though my ideal fighter would've probably been Spitfire III for 1940/41.
I've suggested Fowler flaps exactly because no magic is involved (although several companies in 1930s/40s might've thought of them as of magic - talk majority of German, US, British, Italian and Soviet companies), just like there was no magic in constant speed props or folding wings. 



> Kill Goering very early.
> 
> - Ivan.



Beyond the scope of the thread


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## wuzak (Jun 7, 2019)

tomo pauk said:


> - Avro Lancaster: designed with less guns, more streamlining





Shortround6 said:


> You have to start back with the Manchester, once you are stuck with the Manchester fuselage no amount of plating over openings or putting fairings on the nose and tail it going to get you enough speed to really change things.



Perhaps scrap the Halifax and build the proposed Handley Page High Speed bomber?

No turrets, etc, Using same engines as Manchester (Vulture) but faster and lighter, with similar bomb load capability.

Estimated top speed 380mph.


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## Shortround6 (Jun 7, 2019)

tomo pauk said:


> Monoplane Fury gives experience to Hawker in designing, well, monoplanes. So we might have a less conservative Hurricane, and better performing Typhoon from day one.



Unfortunately the "Fury Monoplane" means many things to many people. Since the plane pretty much only existed on paper how much it actually had in common with the Fury biplanes is certainly subject to question. 
Hawker Fury I which flew in 1931




about 21 built? 
turning this into a monoplane is going to be hard  
Nobody was using flaps yet (except experimenters), you need an all new much larger wing than the existing bottom wing. 

however in 1936 the Fury II made it's appearance. First flight Dec 3rd 1936, over one full year* after* the Hurricane prototype flew. However Hawker built 23 and 75 were built by General aircraft Ltd. in 1936/37. It was intended to be an interim aircraft until the Hurricane could be brought into full production. Obviously very little could have been learned about monoplanes of the Hurricane type at this late date. The several gap is explained by the Air Ministries insistence on building the airplanes powered by the steam cooled Goshawk engine and this meant a lost generation of british fighters. 





> I was not crystal clear - 'ditto' was supposed to mean 'also monoplane' for the Gladiator.



In both the case of the Fury and a monoplane Gladiator you are not "modifying" the aircraft but throwing it out, designing a new plane and using the old name. With the Gladiator again you need an entirely new lower wing (unless you are build a parasol fighter) and since they couldn't fit a .303 browning in the wing the idea that you can fit retracting landing gear in it doesn't seem likely. Leaving you with the Grumman style retract into the fuselage landing gear (which Curtiss licenced and paid Royalties on). 
The Gladiator was a somewhat modified Gauntlet which reduced the need for redesigning _everything_. 





> 4-engined bomber is not lost in case of engine-out, so the AM might see the point there (though I don't hold my breath that they will).


Depends on how crappy the propellers are and how heavy the plane is in relation to the power of the engines  

a 1932 Armstrong-Whitworth design. 




four 340hp 10 cylinder two row radials and 90ft of wingspan and 1886 sq ft of wing. It was supposed to stay in the air on three engines. 

A "proper" two engine bomber should not be lost either. But you need high power engines and feathering props (or at least more than a a two pitch prop) 







> Yes, start early for the gain. OTOH, even getting rid of top and nose turrets and streamlining the nose would've meant that German NFs have a shrunken window of opportunity for shotdown.



The thing is we KNOW the performance figures for the airliner conversions of the Lancaster with all turrets gone and long and rather pointy fairings both front and back. 
If the performance of that plane (totally unarmed) will do the trick all well and good, If it is still too slow then the idea is a non-starter. 





> A new airplane indeed.
> Yes, start with Merlin from the get-go.



again, not modified aircraft but brand new ones using the old name.


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## Shortround6 (Jun 7, 2019)

wuzak said:


> Perhaps scrap the Halifax and build the proposed Handley Page High Speed bomber?
> 
> No turrets, etc, Using same engines as Manchester (Vulture) but faster and lighter, with similar bomb load capability.
> 
> Estimated top speed 380mph.



Is the same guy doing the estimate the guy who estimated the Beaufighter would hit 370mph ?
Or the Typhoon 460mph?

We do have this airplane




top speed about 370mph (with the rockets????) but using 2470hp engines and not 1800hp engines.
Not exactly a low drag design I will grant you but a lot smaller plane than one carrying 8,000lb of small bombs (250lb bombs?) inside.

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## Conslaw (Jun 8, 2019)

I like Pinsong's argument for a production F5F. With first flight in Feb 1940 (three months before the XF4U), it would be pushing it to get a service fighter available in 1941. (Perhaps with "Battle of Kansas" style modifications it could be done.) Admiral Tower slow tracked the plane because of the resources consumed by the twin-engined design, and in truth, he was right, we needed more Wildcats more than we needed 350-mph carrier fighters, but practicality isn't what this thread is about.


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## wuzak (Jun 8, 2019)

Shortround6 said:


> Is the same guy doing the estimate the guy who estimated the Beaufighter would hit 370mph ?
> Or the Typhoon 460mph?



No.




Shortround6 said:


> We do have this airplane
> 
> top speed about 370mph (with the rockets????) but using 2470hp engines and not 1800hp engines.
> Not exactly a low drag design I will grant you but a lot smaller plane than one carrying 8,000lb of small bombs (250lb bombs?) inside.



The proposal was based on the P.13/36 requirements that gave the Manchester and Halifax.


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## Shortround6 (Jun 8, 2019)

wuzak said:


> No.
> 
> 
> 
> ...



A lot of the British proposals of 1938-39 were, shall we say, overly optimistic, due to some faulty assumptions. I tend to look at some of these paper proposals with some skepticism.

To be fair, more than few US proposals of this period (and even into 1942) show just as much if not more optimism, all three "light" fighters for instance (Douglas XP-48, Tucker XP-57 and Bell XP-76) and a bunch more, so it is not just a British thing. The rules that allowed accurate estimates at around 300mph and under (and perhaps in the low 300 mph range) needed a correction factor when you got into the higher 300mph range.

I was using the Brigand as a reality check, Granted it is a bit "lumpier" than the HP proposal but it is smaller, carries a lighter load (externally) so the fuselage is smaller and uses more powerful engines and won't meet the speed. This casts some doubt on the HP bomber doing what was claimed.
It was supposed to carry 4 times the bomb load of an early Mosquito (8 times the prototype Mosquito) using engines only about 50% more powerful? and go just about as fast?

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## wuzak (Jun 8, 2019)

The HP proposal had a maximum bomb load of 8,000lb, but the top speed was probably not with that load on board.

It would be instructive to know what the estimated performance of the Brigand.

Also note that there was the performance estimates of the companies (such as the 460mph Typhoon) and then the MAP also did their own estimates, which were usually lower.

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## Shortround6 (Jun 8, 2019)

The Douglas XP-48 estimate (525mph?) was so far out from what the Army estimated that the Army refused to fund any further development. 

The Brigand was the result of a long and tortuous path that combined the the wings, powerplant and tail (?) of the of the Buckingham bomber




With a skinny fuselage that was being designed for a Beaufighter replacement for the torpedo strike role. As the strike aircraft grew in weight in the design stages it was considered that keeping the Hercules engines would result in too little of a performance gain to make changing aircraft worthwhile (not to mention needing new landing gear and other changes) so as a "quick fix" they adopted the wings, Engines, tail and landing gear of the Buckingham. The Buckingham itself was considered not suitable for use as a tactical or medium bomber at this stage in the war. to keep from scrapping already built components they came up with the Bristol Buckmaster trainer. 




Which is listed as having a 352mph speed at 12,000ft which seems a bit low of an altitude. 

I can't seem to find a picture of the proposed HP high speed bomber but what I recall from a drawing in a book it had a very streamlined nose with no step for the windscreen and the fuselage got fatter behind the cockpit which means pretty much no rearward vision for the pilot. I don't know if this was operationally acceptable.


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## wuzak (Jun 8, 2019)



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## Shortround6 (Jun 8, 2019)

No radiators, no oil coolers, and vision to the rear is non-existent. 

Yes it is a preliminary sketch.


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## wuzak (Jun 8, 2019)

I said Vogt earlier, it should have been Volkert.

It must be noted that his paper was on bombing policy in general, and that he advocated the use of poison gas bombs, predicting that at the altitude and speed he expected of that aeroplane the accuracy would not be good enough to hit targets.


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## tomo pauk (Jun 8, 2019)

Okay, I've gotten more than carried away with my proposals, some of them being more 'let's make it of another shape from ground-up' rather than 'let's improve something that actually existed'.
- P-47: earlier introduction of better prop, wing racks for fuel, perhaps also introduce a self-sealing conformal tank of, say, 75 gals?
- P-51: the V-1650-1 is an obvious improvement, but making the P-51A instead of A-36 also improves WAllied long-range fighter assets, even if mostly for under-20000 ft job (talk anything but ETO bomber escort) from early 1943 on
- P-38: elongated chord of the wing by 20% as suggested by NACA in 1941, coolers in the new leading edge, plus all of late improvements that P-38L had need to be introduced earlier (from better cockpit heating on)
- Bf 109E and on: drop tanks, HMGs under front cowling ASAP, wing cannons retained, main wheel well covers, more streamlined cooling system. Once 3 cannons are standard, delete cowl guns.
- Fw 190: DB 603A option is beaten to death. I'd delete cowl guns ASAP and persist with external ram air intakes for the plain vanilla Fw 190As. The turboed BMW 801 option should be explored, hopefully in a more streamlined package than it was the DB 603A + turbo prototype.


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## Shortround6 (Jun 8, 2019)

Well, Tomo, the Gladiator could have been improved, If it had existed in any other air force it would have gotten at least a two pitch propeller if not a variable pitch (or constant speed?) 





Grumman F3F
Fiat CR 42




doing something with the cowling




Adjustable cowl flaps???? We don't need no bloody adjustable cowl flaps!!!!
Or apparently any baffles on the cylinders? 

Not that the Gladiator was ever going to really beat 109s but some sort of improvements could have been done.


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## fliger747 (Jun 8, 2019)

Most of the things that didn't involve engines that hadn't come to fruition yet were physically possible, it wasn't as if the construction technology for airframes had really advanced much as the war progressed. Just better design and detail in construction. Of course most of this knowledge came about by trial and error.


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## tomo pauk (Jun 8, 2019)

- Me 162 - redesign it for jet engine
- MB.2: perhaps it will not be any more difficult to re-engine it for Merlin than it was for the Italian fighters to receive the DB engine? Add the suggested retractable U/C and we should get a better performer than historical Hurricane
- Gloster F.4/34: indeed, re-engine it for Twin Wasp
- Fw 187: two Czech HS-12Ys + bomb 'belly' to make a fast bomber out of it?
- Fokker D.XXI, Ki 27, A5M: retractable U/Cfor all; 100 oct fuel for the D.XXI, Zuisei for the Japanese + at least two MGs


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## MiTasol (Jun 8, 2019)

Shortround6 said:


> As far as figuring power goes, General motors put out a booklet during WW II comparing 7 different supercharger systems.
> View attachment 540441
> 
> It may be available for download? They used a hypothetical 1000hp engine to illustrate the differences.
> GM owned Allison, a coincidence???



The full title is _Engine Design as Related to Airplane power With special reference to engines and altitudes._

I have previously posted a PDF of the Australian version of that manual and links to two other versions at
Engine design as related to airplane power : with particular reference to performance at varying alt

I can post a non-google PDF of the 1943 US Edition if you want.


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## MiTasol (Jun 8, 2019)

Shortround6 said:


> Unfortunately the "Fury Monoplane" means many things to many people. Since the plane pretty much only existed on paper how much it actually had in common with the Fury biplanes is certainly subject to question.
> Hawker Fury I which flew in 1931 about 21 built?
> turning this into a monoplane is going to be hard
> 
> *Nobody was using flaps yet (except experimenters),* you need an all new much larger wing than the existing bottom wing.



But in 1931 both the DC-1 and Boeing 247 were already on the drawing boards. Both flew in 1933 with flaps from day one, and retractable gears, and variable pitch propellers, and all metal construction except control surfaces and jig built so major components could be swapped for repair.


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## pinsog (Jun 8, 2019)

Conslaw said:


> I like Pinsong's argument for a production F5F. With first flight in Feb 1940 (three months before the XF4U), it would be pushing it to get a service fighter available in 1941. (Perhaps with "Battle of Kansas" style modifications it could be done.) Admiral Tower slow tracked the plane because of the resources consumed by the twin-engined design, and in truth, he was right, we needed more Wildcats more than we needed 350-mph carrier fighters, but practicality isn't what this thread is about.



I think the F5F would follow the same timeline as the Wildcat if they had been told to cancel the Wildcat. If you read the timeline on the F5F it was certainly not a priority.


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## pinsog (Jun 8, 2019)

When you guys are suggesting how fantastic a Seafire would have been, consider how it compared to a 6 gun Wildcat:

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## PAT303 (Jun 8, 2019)

Am I guessing right in saying the Gladiators guns had to fire down the fuselage, through the cowl, between the cylinder banks and dodge the prop before they had even had a chance to do any work?, you'd what to hope you didn't get a squib load.

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## Zipper730 (Jun 8, 2019)

pinsog said:


> When you guys are suggesting how fantastic a Seafire would have been, consider how it compared to a 6 gun Wildcat


I didn't think the 6 gunned set ups were F4F's but FM's.

Either way, I'm surprised the turn-rate of the F4F was significantly greater than the Seafire: From what I remember the regular Hurricane or the Sea Hurricane (forgot which) were similar in turn-rate to the F4F.


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## Zipper730 (Jun 8, 2019)

Some of this will sound a little silly, but with the Admiralty wanting the navalized Spitfire to be built by Fairey, which they said no to, why didn't the Admiralty decide to change the specs for the Firefly into a one seater.

There were proposals that involved either the existing engine or the Napier Sabre.


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## wuzak (Jun 8, 2019)

Zipper730 said:


> I didn't think the 6 gunned set ups were F4F's but FM's.



F4F-4 as well.

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## pinsog (Jun 9, 2019)

Zipper730 said:


> I didn't think the 6 gunned set ups were F4F's but FM's.
> 
> Either way, I'm surprised the turn-rate of the F4F was significantly greater than the Seafire: From what I remember the regular Hurricane or the Sea Hurricane (forgot which) were similar in turn-rate to the F4F.





Zipper730 said:


> I didn't think the 6 gunned set ups were F4F's but FM's.
> 
> Either way, I'm surprised the turn-rate of the F4F was significantly greater than the Seafire: From what I remember the regular Hurricane or the Sea Hurricane (forgot which) were similar in turn-rate to the F4F.



F4F-3 was a 4 gunned Wildcat. F4F-4 had the folding wings, 6 guns and gained 700 pounds or so. FM1 was an F4F-4 built by GM and also had 6 guns. FM2 was the late model hot rod that had 1350 hp and it went back to 4 guns. The Martlet II, III and IV were all 6 gun Wildcats with various engines Wright’s, single stage P&W etc, but all had 6 guns and performed like an F4F-4 or worse

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## Kevin J (Jun 9, 2019)

pinsog said:


> F4F-3 was a 4 gunned Wildcat. F4F-4 had the folding wings, 6 guns and gained 700 pounds or so. FM1 was an F4F-4 built by GM and also had 6 guns. FM2 was the late model hot rod that had 1350 hp and it went back to 4 guns. The Martlet II, III and IV were all 6 gun Wildcats with various engines Wright’s, single stage P&W etc, but all had 6 guns and performed like an F4F-4 or worse


IIRC only F4F-4/4B had 6 guns.


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## pinsog (Jun 9, 2019)

Top left corner on each document. 6 guns. Notice differences in engines and performance of the plane

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## dedalos (Jun 10, 2019)

Regarding the Bf109, Fw 190, i agree almost with everythink tomo pauk says. With the historical industial german capabilities , they could be more competitive.
I woukd like to add 
a) the do 317 b, basicaly the combination of the do217 k with the db610 engine. A formidable combination on paper. Both elements had solved their problems mid war and were in production anyway. 
b)The poor old Bf110G. While a bad air superiority fighter was valuable at everything else. Could be even better 1. Retractable tail landing gear 2. A canopy with more streamlined windshield and internal framing 3.Annulal radiators for the DB605s 4. Remove the slats . Improve high speed aileron operation by hydraulicaly boost, and low speed effectiveness by using the flaps to assist roll control. 5. Wide blade propellers 6. Replace the mg 151s with belt fed MG FFs and the mgs with 4 mg131s or 2 more MGFFs in night fighter role. The oerlicons are light, hard hitting , and the lower velocity is less important against bombers and ground targets, and the Mg 131s are good for strafing and more than enough against soviet fighters.7. MW 50 
These improvements would require some development work and some loss of production, but would not require exotic raw materials. The aircraft would be much better at everything. From night fighting , to CAS missions, and from recce work to u boat escort in biscay bay. With Gm1 would have a good chance against recce aircrafts too.With the exception of the Mw50 such a configuration would be possible to be available in late 43.
An unrealistic senario would be a new single seat version, with 2xDB603s, and new laminar flow wing.Anyway would require less development effort and crews than the Me 410 and would offer much better performance in defence against the areas bombings of the USAF

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## Zipper730 (Jun 10, 2019)

wuzak said:


>


Is this the Handley Page High Speed Bomber?


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## Zipper730 (Jun 10, 2019)

Shortround6 said:


> Everything is trade-offs. Sidewinder superchargers require right angle drives.


Why did the Germans have such an obsession with mounting their superchargers on a 90-degree angle? There was a guy who has a channel on YouTube named Greg called "Greg's Airplanes and Automobiles", and he was also curious about that.



pinsog said:


> Why not a turbocharged F4F-3? No magical time line, just using what we already have. Bugs won't get worked out of turbocharger until early 1942, but plane should perform awesome. Wish I could calculate increase in climb.
> 
> Original 2 speed 2 stage P&W R-1830-76:
> 1200 hp for takeoff
> ...


If I may ask, how did you compute the differences in speed due to different horsepower figures?



pinsog said:


> The other plan I actually prefer is ditch the F4F-3 all together and tell Grumman to develop the XF5F Skyrocket. Original plan was for long nose and long nacelles, then they went to short nose (lower stall speed, super gentle and predictable stall) and short nacelles (no reason that I know of).


The shorter nacelles (R-1820) allowed more forward visibility than the longer R-1830. Performance was still adequate despite the R-1830 being thinner, and it was felt that it the R-1820 was simpler and easier to maintain.



tomo pauk said:


> Okay, I've gotten more than carried away with my proposals, some of them being more 'let's make it of another shape from ground-up' rather than 'let's improve something that actually existed'.


Actually, I gave three allowances for specifications

The existing specification: Basically, the idea would be working within the existing specification, but you could modify or change anything within the boundary of it.
A different winner: Sometimes the problem wasn't the design so much as the winner to the contender: While way after WWII, many feel the YF-23 should have won over the YF-22, for example.
A more realistic/practical specification: Basically the specifications are made more realistic to allow a practical design to be developed, an example would be the He-177 having 4 x DB-601's instead of 2 x DB-606's, or simply not being designed as a dive-bomber.



> - P-38: elongated chord of the wing by 20% as suggested by NACA in 1941, coolers in the new leading edge


This is an idea that's interesting. Do you have any documentation on this suggestion?


> - Fw 190: DB 603A option is beaten to death. I'd delete cowl guns ASAP and persist with external ram air intakes for the plain vanilla Fw 190As. The turboed BMW 801 option should be explored, hopefully in a more streamlined package than it was the DB 603A + turbo prototype.


A DB-603 with a turbo would have given it some great high altitude performance. When you say the idea was beaten to death -- I'm not sure what you mean, however.


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## Shortround6 (Jun 10, 2019)

Zipper730 said:


> Why did the Germans have such an obsession with mounting their superchargers on a 90-degree angle? There was a guy who has a channel on YouTube named Greg called "Greg's Airplanes and Automobiles", and he was also curious about that.




So they could fire a cannon down through the engine and out the prop hub.

Supercharger has to go someplace, either off to one side or the other or push it down below the cannon or maybe even lay it flat ( I don't think anybody did that). 
Hispanos didn't use a very big supercharger and they pushed it down low on the engine and the cannon went over the top. 






If you want to use a bigger supercharger you have to figure out where to put it.

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## pinsog (Jun 10, 2019)

“If I may ask, how did you compute the differences in speed due to different horsepower figures?”
New hp/old hp = X Cube root of X multiplied times old speed

1200 hp/1000 hp = 1.2. Cube root of 1.2 is 1.06265857. 1.06265857 x 330 mph (at 19000) = 350 mph.


“The shorter nacelles (R-1820) allowed more forward visibility than the longer R-1830. Performance was still adequate despite the R-1830 being thinner, and it was felt that it the R-1820 was simpler and easier to maintain.”

The lengthened nacelles doesnt refer to how much the engine sticks out the front. Look at the short nosed F5F, the engine nacelles stop midwingand then the long nose F5F the nacelles extend past the rear edge of the wing. The P&W 1830 was never considered, only the P&W 1535 which wasn’t going to be supported by P&W, so they went with the Wright 1820, best guess is because it was identical in weight to the 1535.








See the difference?


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## Shortround6 (Jun 10, 2019)

There was _supposed _to be a two stage version of the R-1535 but it never got built. So yes, the R-1820 was the easiest engine to use as a substitute, at least to get something flying.

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## tyrodtom (Jun 10, 2019)

Shortround6 said:


> So they could fire a cannon down through the engine and out the prop hub.
> 
> Supercharger has to go someplace, either off to one side or the other or push it down below the cannon or maybe even lay it flat ( I don't think anybody did that).
> Hispanos didn't use a very big supercharger and they pushed it down low on the engine and the cannon went over the top.
> ...



I notice the exhaust and intake is both on the outside of the V, leaving the inside for the cannon.
Maybe one of the reasons the Hispano was such a underperformer HP wise. 
The intake passages to the intake valve had to be pretty convoluted through that head from the outside

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## GrauGeist (Jun 10, 2019)

The "long nose" XF5F was actually the Army's XP-50. The longer nose on the XP-50 was for the nose-gear.

There was only one of each ever built and they both used the Wright R-1820.
XF5F: R-1820-40/42
XP-50: R-1820-67/69 turbosupercharged (which is why it had larger nacelles than the XF5F)

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## pinsog (Jun 10, 2019)

GrauGeist said:


> The "long nose" XF5F was actually the Army's XP-50. The longer nose on the XP-50 was for the nose-gear.
> 
> There was only one of each ever built and they both used the Wright R-1820.
> XF5F: R-1820-40/42
> XP-50: R-1820-67/69 turbosupercharged (which is why it had larger nacelles than the XF5F)



No sir. The XF5F was rebuilt from a short nose short nacelle aircraft into a long nose long nacelle aircraft.









The XP50 had a tricycle landing gear.

You are correct that the XP50 was turbocharged and the XF5F was not, even when it had long nacelles.


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## Shortround6 (Jun 10, 2019)

Unfortunately the longer nose, longer nacelles, prop spinners and a few other changes still didn't get the drag low enough get the performance where they wanted.


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## Shortround6 (Jun 10, 2019)

tyrodtom said:


> I notice the exhaust and intake is both on the outside of the V, leaving the inside for the cannon.
> Maybe one of the reasons the Hispano was such a underperformer HP wise.
> The intake passages to the intake valve had to be pretty convoluted through that head from the outside



There were a lot of reasons for the Hispano being an underperformer in 1939-40, one of them is that it was an engine from the late 20s that "inherited" some of it's design features (and design limits, like bore spacing) from the WW I Hispano V-8s. One source claims Hispano superchargers would get so hot they would blister the paint on the supercharger. Poor paint or hot supercharger 

Point is that if you tried to mount a Merlin supercharger on the back of the engine it would hit the bottom of the cannon. The Germans ran the intake air on the inside of the V. the German guns were not bolted to the engine but the barrels fit in a 70mm ID tube that ran from the back of the engine to the reduction gear. the whole cannon breach and feed system was hanging just in back of the engine about where you would want the supercharger to go.


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## pinsog (Jun 10, 2019)

Shortround6 said:


> Unfortunately the longer nose, longer nacelles, prop spinners and a few other changes still didn't get the drag low enough get the performance where they wanted.



They needed more power. If they had used turbocharged Wright 1820’s it would have probably equaled an early P38 in top speed and clobbered it in climb.

Look at the XF5F test vs a P38E. At 20,000 feet a P38E was doing 352 mph on 750 hp per engine. Top speed of an XF5F at 20,000 feet was 352 mph. Those 2 speed Wright’s couldn’t have been putting out over 750 hp. My guess is they were about 700 hp each. I think an XF5F and a P38E had about the same drag.


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## Zipper730 (Jun 10, 2019)

pinsog said:


> “If I may ask, how did you compute the differences in speed due to different horsepower figures?”
> New hp/old hp = X Cube root of X multiplied times old speed
> 
> 1200 hp/1000 hp = 1.2. Cube root of 1.2 is 1.06265857. 1.06265857 x 330 mph (at 19000) = 350 mph.


Oh, okay: I get it now


> The lengthened nacelles doesnt refer to how much the engine sticks out the front. Look at the short nosed F5F, the engine nacelles stop midwingand then the long nose F5F the nacelles extend past the rear edge of the wing.


So, it has to do with the nacelle extending further rearward...


> The P&W 1830 was never considered


Actually, I have a book on the plane and I thought I remembered that it was looked at very early on...


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## pinsog (Jun 10, 2019)

Zipper730 said:


> Oh, okay: I get it now
> So, it has to do with the nacelle extending further rearward...
> Actually, I have a book on the plane and I thought I remembered that it was looked at very early on...



Correct on the nacelle extending rearward. I have the same book, the first engine they considered was a P&W 1535 but as Shortround said, they decided not to do a 2 stage version. The Wright 1820 was the same weight, I think that is why they chose it


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## pinsog (Jun 10, 2019)

A P38E does 340.5 mph on 1150 hp per engine at 5000 feet
The XF5F did 326 mph on 1000 hp per engine at 4500 feet.

Give the XF5F 1150 per engine and

1150/1000 = 1.15. Cube root of 1.15 is 1.047689. 1.047689 X 326 = 341.5 mph

Same hp, same speed, 2 different altitudes. They should have turbocharged the XF5F and they could have, essentially, had a carrier based P38E that weighed 3000 pounds less, after adding armor and seal sealing tanks, and was 10 feet shorter and 10 foot less wingspan.


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## Zipper730 (Jun 11, 2019)

pinsog said:


> 1150/1000 = 1.15. Square root of 1.15 is 1.047689. 1.047689 X 326 = 341.5 mph


I thought you were supposed to use cube-root, but the numbers look okay.


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## pinsog (Jun 11, 2019)

Zipper730 said:


> I thought you were supposed to use cube-root, but the numbers look okay.



Your correct. I used cube root but typed square root. I’m going to edit my previous post


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## tomo pauk (Jun 12, 2019)

Zipper730 said:


> Actually, I gave three allowances for specifications
> 
> The existing specification: Basically, the idea would be working within the existing specification, but you could modify or change anything within the boundary of it.
> A different winner: Sometimes the problem wasn't the design so much as the winner to the contender: While way after WWII, many feel the YF-23 should have won over the YF-22, for example.
> A more realistic/practical specification: Basically the specifications are made more realistic to allow a practical design to be developed, an example would be the He-177 having 4 x DB-601's instead of 2 x DB-606's, or simply not being designed as a dive-bomber.



Thank you.
Per #1, seems my idea of Fw 190 + DB 601/605 works, so does the high-wing Ju 88, as well as small+light fuselage B-26.
Not sure for Fury and Gladiator being designed as monoplanes?



> This is an idea that's interesting. Do you have any documentation on this suggestion?



Download: link



> A DB-603 with a turbo would have given it some great high altitude performance. When you say the idea was beaten to death -- I'm not sure what you mean, however.



Beaten to death: almost every alternative Fw 190 discussed has DB 603A in the nose by some time 1943.


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## Shortround6 (Jun 12, 2019)

tomo pauk said:


> Not sure for Fury and Gladiator being designed as monoplanes?



The trouble is, even if it happened, you don't get anything really useable and you don't get a lot of good design experience, except perhaps what_ not_ to do  
Supermarine 224




Fixed gear, thick wing, open cockpit of early Bristol 133




later




No flaps or flaps added later? Landing gear makes a P-35 look good. Why the fuselage is that fat for the engine it used or what had to go in it? 
The Gladiator was never intended to be a "standard" fighter. It was another of the all too many "we need an interim plane NOW, to equip the new squadrons with while we work on the new monoplanes." that the British ordered in 1936-37. Only eight squadrons in England were ever equipped with them, some replaced the Bristol Bulldog. 




But some squadrons had already re-equipped with Hurricanes by Sept of 1939. At which point they were being fosted off on the RN or overseas stations. 

The Gladiator could easily have seen _some_ improvement (like many other British planes) by fitting it with a 2 speed or variable pitch propeller. Given the British shortage of production capacity for modern propellers it was probably pretty far down on the list of priorities.


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## tomo pauk (Jun 12, 2019)

Shortround6 said:


> The trouble is, even if it happened, you don't get anything really useable and you don't get a lot of good design experience, except perhaps what_ not_ to do
> Supermarine 224
> Fixed gear, thick wing, open cockpit of early Bristol 133
> later
> No flaps or flaps added later? Landing gear makes a P-35 look good. Why the fuselage is that fat for the engine it used or what had to go in it?



Sometimes, even knowing what not to do is a good thing 



> The Gladiator was never intended to be a "standard" fighter. It was another of the all too many "we need an interim plane NOW, to equip the new squadrons with while we work on the new monoplanes." that the British ordered in 1936-37. Only eight squadrons in England were ever equipped with them, some replaced the Bristol Bulldog.
> But some squadrons had already re-equipped with Hurricanes by Sept of 1939. At which point they were being fosted off on the RN or overseas stations.
> 
> The Gladiator could easily have seen _some_ improvement (like many other British planes) by fitting it with a 2 speed or variable pitch propeller. Given the British shortage of production capacity for modern propellers it was probably pretty far down on the list of priorities.



Hmm, yes, how about the Gauntlet monoplane then?


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## swampyankee (Jun 12, 2019)

Vaguely back on topic -- how about a better air filtration system for the Merlin, at least as installed on the Spitfire and Hurricane?


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## Shortround6 (Jun 12, 2019)

swampyankee said:


> Vaguely back on topic -- how about a better air filtration system for the Merlin, at least as installed on the Spitfire and Hurricane?




I think they finally got one. 
The Updraft carb was probably a mistake in hindsight as any air intake on the bottom of the plane and 4-6 feet behind the propeller is going to catch all kinds of crud the prop blast/swirl kicks up, especially when the tail wheel comes up and the prop is only inches from the sod, dirt, sand, coral, etc, etc.

P-40s and Allison P-51s had the air intake on top and only inches behind the prop so their intake of self made grinding compound was much less, However formation take-offs needed care as your buddy's/wingman's plane could sure kick up enough crap to kill your engine. 

The Vokes filter was probably overkill but few people had designed air filters for aircraft at that time. 
The B-26 sure got some large air intakes when they sized them to fit filters.


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## Kevin J (Jun 12, 2019)

Shortround6 said:


> I think they finally got one.
> The Updraft carb was probably a mistake in hindsight as any air intake on the bottom of the plane and 4-6 feet behind the propeller is going to catch all kinds of crud the prop blast/swirl kicks up, especially when the tail wheel comes up and the prop is only inches from the sod, dirt, sand, coral, etc, etc.
> 
> P-40s and Allison P-51s had the air intake on top and only inches behind the prop so their intake of self made grinding compound was much less, However formation take-offs needed care as your buddy's/wingman's plane could sure kick up enough crap to kill your engine.
> ...



The Vokes filter also contained the extra oil tank required for ferry flights. That's why its so big and bulky.


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## llemon (Jun 13, 2019)

Messerschmitt 109

1. fit "all-round" vision canopy as designed for the 209 with cut down rear fuselage. This was proposed for the F
2. New wing with twin spars, inward retracting gear and thinner section at root and tip. Such a wing was test flown on the v31. Make it square tipped, same planform as the E.
3. Single radiator in belly slightly behind wing, This volume is occupied by the fuel tank so move the tanks between the wing spars soviet style. Later move to drum type radiator. 
4. Armament 1 MG151 + 2 MG 131 or 3 MG 131
5. Enlarged vert stab with pilot adjustable trim tab
6. Replace slats with fence

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## Kevin J (Jun 13, 2019)

llemon said:


> Messerschmitt 109
> 
> 1. fit "all-round" vision canopy as designed for the 209 with cut down rear fuselage. This was proposed for the F
> 2. New wing with twin spars, inward retracting gear and thinner section at root and tip. Such a wing was test flown on the v31. Make it square tipped, same planform as the E.
> ...


So its a completely new design that enters service in 1941 when you need to contest the Spitfire immediately which outclasses the Bf 109E. That's not a good idea. Why not put a liquid cooled engine in the Fw 190.


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## Shortround6 (Jun 13, 2019)

It has always been a wonder to me that the germans could not come up with blown canopy or didn't until very late. 
A Malcom style hood on the 109 might of done wonders for visibility and/or pilots ability to operate in the cockpit if even heading to towards being tall  
fixing that rather appalling windscreen shouldn't have been that hard either. I mean it would be hard to actually do worse. 

Wing fences probably won't do the job the the slats do.

three MG 131s is pretty poor armament. The MG 131 using the least powerful 12.7mm-13.2mm cartridge of the war. Lowest velocity=longest times of flight to target just to get hits. 

Lack of trim tabs is harder to comprehend.


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## pbehn (Jun 13, 2019)

Kevin J said:


> So its a completely new design that enters service in 1941 when you need to contest the Spitfire immediately which outclasses the Bf 109E. That's not a good idea. Why not put a liquid cooled engine in the Fw 190.


Probably because if you do every additional new FW190 is one less Bf109.


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## Kevin J (Jun 13, 2019)

pbehn said:


> Probably because if you do every additional new FW190 is one less Bf109.


I mean like a Jumo 213 or Db 603.


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## pbehn (Jun 13, 2019)

Kevin J said:


> I mean like a Jumo 213 or Db 603.


I didn't realise the Germans had a few thousand lying about.

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## NVSMITH (Jun 13, 2019)

-A couple of things about the P-38 have always had me curious:
1) Why was so much effort wasted on the "Chain Lightning" when a balanced two seat cockpit made more sense? I don't mean the shoe-horn version made for the P-38M, but a real, extended but balanced, two seater. 
2) Did anyone ever posit using radial engines on the bird? It would have made a heck of a ground attack ship given some pilot protection.


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## NVSMITH (Jun 13, 2019)

-A couple of things about the P-38 have always had me curious:
1) Why was so much effort wasted on the "Chain Lightning" when a balanced two seat cockpit made more sense? I don't mean the shoe-horn version made for the P-38M, but a real, extended but balanced, two seater. 
2) Did anyone ever posit using radial engines on the bird? It would have made a heck of a ground attack ship given some pilot protection.


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## tomo pauk (Jun 13, 2019)

NVSMITH said:


> -A couple of things about the P-38 have always had me curious:
> 1) Why was so much effort wasted on the "Chain Lightning" when a balanced two seat cockpit made more sense? I don't mean the shoe-horn version made for the P-38M, but a real, extended but balanced, two seater.
> 2) Did anyone ever posit using radial engines on the bird? It would have made a heck of a ground attack ship given some pilot protection.



1. - The (X)P-58 was supposed to represent a new advance in performance and firepower. Like many aircraft before or after it, it was not exactly what people were expecting. It took time for realities of the war to settle in, too.
2. - I did  It was hard enough for Lockheed to manufacture enough of V-1710-powered P-38s historically, so even if the radial-powered version is designed, it will not be produced until/unless there is a factory available to make them.


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## pinsog (Jun 13, 2019)

I have always liked the P38, but it was a very difficult aircraft to maintain for ground personnel. I also like the idea of a radial twin engine fighter, but if your going to do that why not just turbocharge the XF5F Skyrocket?

Run the numbers against the only test we have on the Skyrocket using 2400 hp from SL to 25,000 feet instead of what it actually did and level speed matches a P38E almost exactly. Using overload weight of 10,900 pounds for the XF5F and adding 150 pounds of armor, 200 pounds for selfsealing tanks and 500 pounds for turbochargers you get 11,750. Add 62 gallon tanks in the outer wings like an F4U-1 and you have 400 gallons of fuel internal. 11,750 plus 750 pounds of fuel, say wing tanks and plumbing add 300 pounds and your at 12,800 pounds, 2000 pounds less than an early P38 with 100 more hp and 100 gallons more fuel. Climb should be terrific, top speed equal. No dive issues either, XF5F was dived vertically to 505 mph


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## davparlr (Jun 13, 2019)

I have always been perplexed with the huge wing area of the P-59 an I tend to think that this was one of the major reasons the p-59 was a disappointment in top speed (the meteor may also have been limited by this). Here are some comparisons of early jets wing area:
P-59 386 sq ft
Me 262 234
P-80 237
Meteor 350
I think that if they had built the P-59, which appears to me to be a clean design with better engine airframe integration than either the Me 262 and Meteor, with much smaller wings, say like the P-63 wings (248 sq ft), the AF may have been surprised with the performance of the P-59 which may have been equivalent to the Me 262 and the P-80, and been more timely implemented in countering the Me 262. Since it flew only two and a half months after the Me 262 flew its too bad they didn't try it with smaller wings, they seemed to have time to do so.


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## Shortround6 (Jun 13, 2019)

The XP-58 saga was a tragedy of comic proportions or a comedy of tragic proportions, your choice 

Go to Joe Baugher's web site.

Lockheed XP-58 

Seldom in the course of human history have so many toiled so hard and so long for so little result.


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## wuzak (Jun 13, 2019)

NVSMITH said:


> -A couple of things about the P-38 have always had me curious:
> 1) Why was so much effort wasted on the "Chain Lightning" when a balanced two seat cockpit made more sense? I don't mean the shoe-horn version made for the P-38M, but a real, extended but balanced, two seater.
> 2) Did anyone ever posit using radial engines on the bird? It would have made a heck of a ground attack ship given some pilot protection.



Why radial engines weren't really considered for the P-38:
https://static.thisdayinaviation.com/wp-content/uploads/tdia//2018/06/XB-38_engine.jpg 
Vega XB-38 Archives - This Day in Aviation 

That is the V-1710 installed in the Lockheed/Vega XB-38, formerly a B-17E.

The nacelle is designed for the R-1820, and you can see that there is a lot of space around the engine.

As to why radial engines weren't considered for the XP-58, that is a little less clear cut.

Originally it was intended to have the Continental IV-1430, which would have had a similar frontal area to the V-1710.

It was realised that the IV-1430 would be under-powered, so they changed to the Pratt & Whitney X-1800/XH-2600. That was taller, but narrower. It was also cancelled before the XP-58 program was too far along.

Next choice was the Wright R-2160 Tornado. This was a liquid cooled radial engine. It consisted of three 14 cylinder modules. The R-2160 was expected to make more power (2,500hp) than the best available radial (the R-2800) at that time. The R-2160 had a diameter of 36 inches compared to the R-2800's 52.5 inches.

The engine the aircraft actually flew with was the V-3420. At 2,600hp (Lockheed XP-58 Chain Lightning - Wikipedia says 3,000hp) the V-3420 was as powerful, or powerful, than the latest R-2800s.

Of the engines proposed for the XP-58, the V-3420 was closest in size to a radial which could feasibly power the aircraft - the R-2800 or R-3350. It was wider than the radials, but not as tall.

The XP-58 started out as a fighter, either 1 or 2 seat, but its role was being changed all the time. At the end it was to be a low altitude attack aircraft.

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## wuzak (Jun 13, 2019)

Shortround6 said:


> The XP-58 saga was a tragedy of comic proportions or a comedy of tragic proportions, your choice
> 
> Go to Joe Baugher's web site.
> 
> ...



So the R-2800 was actually considered, but it was thought that the performance would be insufficient.


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## Shortround6 (Jun 13, 2019)

davparlr said:


> I have always been perplexed with the huge wing area of the P-59 an I tend to think that this was one of the major reasons the p-59 was a disappointment in top speed (the meteor may also have been limited by this). Here are some comparisons of early jets wing area:
> P-59 386 sq ft
> Me 262 234
> P-80 237
> ...



trouble is the early jets were real fuel hogs and






they carried 290 gallons of fuel in the wings. Range was a whopping 240 miles at 20,000ft with a cruising speed of 298mph (?) 
A pair of 150 gallon drop tanks got you to 520 miles. 

Cutting the wing area without cutting the fuel load can be done but you are going to have some short, stumpy wings.

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## Zipper730 (Jun 13, 2019)

*Regarding the P-38,*



tomo pauk said:


> P-38: elongated chord of the wing by 20% as suggested by NACA in 1941, coolers in the new leading edge...


The report that you posted listed March, 1942. That also corresponds with the time period that they modified the wind-tunnels in NACA for 0.75 mach. That said, it would have definitely been a nice touch.


> Beaten to death: almost every alternative Fw 190 discussed has DB 603A in the nose by some time 1943.


Understood



NVSMITH said:


> Why was so much effort wasted on the "Chain Lightning" when a balanced two seat cockpit made more sense? I don't mean the shoe-horn version made for the P-38M, but a real, extended but balanced, two seater.


Like for a night-fighter?

*Regarding the Hurricane & Spitfire,*



Shortround6 said:


> The Updraft carb was probably a mistake in hindsight as any air intake on the bottom of the plane and 4-6 feet behind the propeller is going to catch all kinds of crud the prop blast/swirl kicks up, especially when the tail wheel comes up and the prop is only inches from the sod, dirt, sand, coral, etc, etc.
> 
> P-40s and Allison P-51s had the air intake on top and only inches behind the prop so their intake of self made grinding compound was much less, However formation take-offs needed care as your buddy's/wingman's plane could sure kick up enough crap to kill your engine.


Did the US use formation takeoffs to the same effect as the RAF? I'm curious because the RAF seemed to do that very liberally with fighters, and that would explain problems with dust and dirt.

*Regarding the XF5F,*



pinsog said:


> No dive issues either, XF5F was dived vertically to 505 mph


At what altitude did it reach 505 if I may ask? I'm just trying to determine mach number...

*Regarding the XP-59,*



davparlr said:


> I have always been perplexed with the huge wing area of the P-59 an I tend to think that this was one of the major reasons the p-59 was a disappointment in top speed (the meteor may also have been limited by this).


The reason had to do with the fact that, in order to achieve sufficient thrust, you'd need two engines.

This requires the aircraft to be able to fly decently well with one engine out, and that means L/D has to be low enough to allow the engine to keep the plane level at high altitude, as well as land adequately at low-speed, as well as the ability to keep the plane in a straight-line, but I have a hunch power was more of a concern here, for the following reasons.

The P-59 & Meteor both had large wings (you list the Meteor as having a wing area of 350 ft^2, though that was from some of the Mk.IV's and on; the earlier's had a wing-area of 375 ft^2) and both had twin-engines, with different installation (P-59: In the wing-root; Meteor: At about 1/3 the span, give or take 10%).
The Vampire & P-80 had enough engine power to fly with one engine, and both appeared to have smaller and more heavily loaded wings.



> I think that if they had built the P-59, which appears to me to be a clean design with better engine airframe integration than either the Me 262 and Meteor


I'm not sure about that, the basic concept of mounting them in the roots isn't bad, but one of the following ultimately served to undermine it

Poor inlet design
Poor inlet-fuselage interface
Poor wing-inlet interface
Some mixture of the above
I would have favored a higher aspect ratio wing like the He-280, which would have allowed the same lift in less wing-area: It could exceed 500 mph: The problem with the P-59 was that, it was on a very quick time-table (approximately 9 months), using a new engine, and thanks to secrecy, they were not allowed access to the wind-tunnels at certain times. 

They wanted to produce a design that was as simple as possible, without any unknowns.



Shortround6 said:


> trouble is the early jets were real fuel hogs and they carried 290 gallons of fuel in the wings. Range was a whopping 240 miles at 20,000ft with a cruising speed of 298mph (?)


If I recall their cruising speed was more like 395 mph, with a range of around 400 if I recall.


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## pinsog (Jun 13, 2019)

No idea on altitude of XF5F 505 mph vertical dive. It was done on February 1, 1941 with “Connie” Converse as the pilot. He had dived it to 487 mph on January 31. All the info available

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## pinsog (Jun 13, 2019)

I believe the problem with the Hurricane and Spitfire ingesting dirt was the intake was under the engine, the intake on a P40 for instance was on top of the engine. Imagine driving down a dirt road in a truck with the air intake either under the truck or on top of the hood. I think it was that simple of a problem

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## wuzak (Jun 13, 2019)

> As might be expected for such a revolutionary system of aircraft propulsion, there were serious problems right from the start. The jet engines were too heavy in relation to the amount of power they could develop, and their exhaust was so hot that the turbine blades regularly overheated and often broke off with catastrophic results. The maximum speed was 404 mph at 25,000 feet, somewhat below expectations. The engine installation was found to result in an inordinate amount of aerodynamic interference, and the aircraft was subject to severe directional snaking, making it a poor gun platform. Nevertheless, work on the P-59 continued unabated, and remedies were eventually found for its long list of faults.





> The first YP-59A reached Muroc in June of 1943, and the USAAF gave the aircraft the name *Airacomet*. The first YP-59A flew in August of 1943. The YP-59A had more powerful 1650 lb. st. General Electric I-16 (J31) turbojets. However, the YP-59A showed little improvement in performance over the XP-59A. Empty weight increased to 7626 pounds, and *maximum speed* was a disappointing *409 mph at 35,000 feet*. Service ceiling was 43,200 feet. The last four YP-59As had a heavier armament--three 0.50-inch machine guns and a single 37-mm cannon, which had been standardized for the production P-59A.





> The production P-59A differed very little from the YP-59A. Only the first twenty of the P-59A order were actually completed as P-59As. Serials were 44-22609/22628. Most of these P-59As were powered by a pair of 1650 lb. s.t. General Electric J31-GE-3 turbojets, although the last few were powered by uprated 2000 lb. st. J31-GE-5 turbojets. The J31-GE-5-powered P-59A had a *maximum speed of 413 mph at 30,000 feet* and *380 mph at 5000 feet*. *Range on internal fuel was 240 miles*, and range with two 125-Imp. gall. drop tanks was 520 miles. An altitude of 10,000 feet could be reached in 3.2 minutes, and 20,000 feet in 7.4 minutes. Weights were 7950 pounds empty, 10,822 pounds loaded, 12,700 pounds maximum. Dimensions were wingspan 45 feet 6 inches, length 38 feet 10 inches, height 12 feet 4 inches, and wing area 385.8 square feet. Armament consisted of one 37-mm cannon and three 0.50-inch machine guns, all mounted in the nose. In addition, two 1000-pound bombs or eight 60-pound rockets could be carried on underwing racks.





> The twenty-first and remaining twenty-nine Airacomets of the P-59A order were completed as P-59Bs. Serials were 44-22629/22658. They had the uprated J31-GE-5 jets of the later P-59As, but had *internal fuel capacity increased by 55 Imp gall.* *Maximum range was increased to 950 miles*. Empty weight of the P-59B was increased to 8165 pounds and normal and maximum loaded weights were 11,049 pounds and 13,700 pounds respectively. The last P-59B was delivered in May of 1945.



Bell P-59 Airacomet 

*Specifications (P-59B)*
_Data from_ The American Fighter[17]

*General characteristics*

*Crew:* one
*Length:* 38 ft 10 in (11.84 m)
*Wingspan:* 45 ft 6 in (13.87 m)
*Height:* 12 ft 4 in (3.76 m)
*Wing area:* 386 sq ft (35.86 m²)
*Empty weight:* 8,165 lb (3,704 kg)
*Loaded weight:* 11,040 lb (5,008 kg)
*Max. takeoff weight:* 13,700 lb (6,214 kg)
*Powerplant:* 2 × General Electric J31-GE-5 turbojets, 2,000 lbf (8.9 kN) each
*Performance*

*Maximum speed:* 413 mph (359 knots, 665 km/h) at 30,000 ft (9,140 m)
*Cruise speed:* 375 mph (326 knots, 604 km/h)
*Range:* 375 mi (326 nm, 604 km)
*Service ceiling:* 46,200 ft (14,080 m)
*Climb to 30,000 ft (9,140 m):* 15 min 30 s
*Armament*

*Guns:* 
1x 37 mm cannon
3x .50 cal (12.7 mm) machine guns

*Rockets:* 8× 60 lb (30 kg) rockets
*Bombs:* 2,000 lb (910 kg) bombs
Bell P-59 Airacomet - Wikipedia


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## Shortround6 (Jun 14, 2019)

pinsog said:


> I believe the problem with the Hurricane and Spitfire ingesting dirt was the intake was under the engine, the intake on a P40 for instance was on top of the engine. Imagine driving down a dirt road in a truck with the air intake either under the truck or on top of the hood. I think it was that simple of a problem


 The problem pretty much was that simple.

The solution was harder. 

for the allison 




carb is the black object at the top rear covered with some netting. Air can be brought from the front of the plane across the top of the engine and then one 90 degree turn and it is in the carb with a fair degree of ram.

for the Merlin with the updraft carb things are bit more complicated




Carb is in the bottom right hand corner of the picture and the air needs to be going up when it hits the carb inlet/s. 
The under fuselage scoop works great in clean conditions, one 90 degree bend just like the Allison but trying to use a top mounted scoop means two more 90 degree bends or a 180 and the loss of some the RAM effect. For the Spitfire putting an air intake on the top pd the fuselage means a poorer view from the cockpit. You could try side inlets/scoops but you still need to get the air down to the bottom rear of the engine. Low mounted side scoops may not be that much of an improvement on a single engine plane. 





Or design/copy a down draft carb and change a bunch of stuff on the back of the engine and in the engine compartments of the planes you want to use it in.


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## wuzak (Jun 14, 2019)

In comparison to the P-59A, here is a performance chart for the Meteor I

http://www.wwiiaircraftperformance.org/meteor/meteor-chart-8june45.jpg 

Range was about the same as a P-59A.


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## wuzak (Jun 14, 2019)

davparlr said:


> I have always been perplexed with the huge wing area of the P-59 an I tend to think that this was one of the major reasons the p-59 was a disappointment in top speed (the meteor may also have been limited by this). Here are some comparisons of early jets wing area:
> P-59 386 sq ft
> Me 262 234
> P-80 237
> ...



The wing span of teh Meteor was changed. 

The Meteor I, III and early IV had a wing span of 43ft (45ft 6in for P-59), while later IVs and the F8 had a span of 37.2ft.

Gloster Meteor F Mk.I 
Gloster Meteor F Mk.III 
Gloster Meteor F Mk.IV 

Was 350 sq.ft. for the standard, long span wings?


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## wuzak (Jun 14, 2019)

The advantage of engine installations like the Me 262 and the Meteor over those like the P-59A was that it was easier to swap engines.

The first Meteor flight was the prototype fitted with two Halford/de Havilland H.1s, rather than the Rolls-Royce Wellands destined for production. A later prototype flew with Metrovicks F.2s.

It would have been a lot more work to fit these different engines in the P-59A - the H.1 was bigger than the Welland, while the F.2 was smaller in diameter but longer.


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## Simon Thomas (Jun 14, 2019)

Re Merlin inlet

The Hornet had the inlet arranged better. No doubt it could have been done earlier, however the RR staff were already flat out with other priorities.

hornet | tailor-made power | series tailor-made | 1946 | 0165 | Flight Archive


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## Shortround6 (Jun 14, 2019)

Simon Thomas said:


> Re Merlin inlet
> 
> The Hornet had the inlet arranged better. No doubt it could have been done earlier, however the RR staff were already flat out with other priorities.
> 
> hornet | tailor-made power | series tailor-made | 1946 | 0165 | Flight Archive


It also looks like the carb/fuel injection unit was flipped to be a down draft unit.

The Peregrine used a down draft carb so it was nothing new to RR. It may very well be as you say, other things were given higher priority.


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## davparlr (Jun 14, 2019)

Shortround6 said:


> trouble is the early jets were real fuel hogs and they carried 290 gallons of fuel in the wings. Range was a whopping 240 miles at 20,000ft with a cruising speed of 298mph (?)



True, fuel was always an issue with early jets and a new wing would not hold as much as the old. About a 150 gallons of fuel would have to be carried in the fuselage. However, for just testing less fuel would be needed.



> Cutting the wing area without cutting the fuel load can be done but you are going to have some short, stumpy wings.



Not necessarily. The new wing would have to be a complete redesign. Perhaps the P-63s wing could be adapted. Less wing area could make a significant difference. Depending on the manufacturing breakdown it could be as simple as a bolt-on change. They may not even need to change the landing gear. Some work, but if they could get another 100 mph out of the plane, it would be important.



Zipper730 said:


> *Regarding the XP-59,*
> 
> This requires the aircraft to be able to fly decently well with one engine out, and that means L/D has to be low enough to allow the engine to keep the plane level at high altitude, as well as land adequately at low-speed, as well as the ability to keep the plane in a straight-line, but I have a hunch power was more of a concern here, for the following reasons.



This seems not to be an issue with the He 280 or the Me 262. The 280 had less power available and slightly less gross weight than the P-59, and 262 had slightly more power available but was much heavier. Both had about 60% of the wing area of the P-59.



> I'm not sure about that, the basic concept of mounting them in the roots isn't bad, but one of the following ultimately served to undermine it
> 
> 
> Poor inlet design
> ...



What you say is true. This technology would have been poorly understood in the 1941-42 timeframe that we are talking about and certainly simplified by podded engines. But all could be addressed, as was the inlet problems with the P-80, with reasonable effort. It is interesting to note these items are still an issue in modern stealth aircraft.



> The problem with the P-59 was that, it was on a very quick time-table (approximately 9 months), using a new engine, and thanks to secrecy, they were not allowed access to the wind-tunnels at certain times.
> 
> They wanted to produce a design that was as simple as possible, without any unknowns.



I agree. I think one of the problems was that the US aircraft industry (except maybe Lockheed) unlike the German aircraft industry, did not understand the potential of the jet engine, and that was mainly speed. I am sure they designed it to common practices of propeller driven aircraft.



Zipper730 said:


> Was 350 sq.ft. for the standard, long span wings?



It was the F.8 37 foot.



> The advantage of engine installations like the Me 262 and the Meteor over those like the P-59A was that it was easier to swap engines.
> 
> The first Meteor flight was the prototype fitted with two Halford/de Havilland H.1s, rather than the Rolls-Royce Wellands destined for production. A later prototype flew with Metrovicks F.2s.
> 
> It would have been a lot more work to fit these different engines in the P-59A - the H.1 was bigger than the Welland, while the F.2 was smaller in diameter but longer.





Yes, you are correct on the growth of the P-59. But these engines did not make it into the war whereas a properly designed P-59 with a -3 or -5 engine could have possibly been competitive in the war.


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## GrauGeist (Jun 14, 2019)

The actual XP-59 may have held more promise as a jet fighter than the YP-59/P-59A, but it was intended to have a piston engine and was cancelled.


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## Zipper730 (Jun 15, 2019)

davparlr said:


> This seems not to be an issue with the He 280 or the Me 262.


Both had higher aspect ratios which can often yield more lift for the same wing-area.


> What you say is true. This technology would have been poorly understood in the 1941-42 timeframe that we are talking about and certainly simplified by podded engines.


Correct


> But all could be addressed, as was the inlet problems with the P-80, with reasonable effort.


Correct.


> I agree. I think one of the problems was that the US aircraft industry (except maybe Lockheed) unlike the German aircraft industry, did not understand the potential of the jet engine, and that was mainly speed.


Honestly, the L-133 had serious potential. The engine design they produced was way too complicated.


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## davparlr (Jun 18, 2019)

Zipper730 said:


> Both had higher aspect ratios which can often yield more lift for the same wing-area.


I would not have just chopped off part of that awful wing, I would have designed and installed a low drag high speed wing ala P-80/Me 262. I would have wanted to see how fast it could go. A cleaned up P-59 with optmize inlets and more thrust should be close to equal or faster than the P-80/Me 262.


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## P-39 Expert (Jun 19, 2019)

swampyankee said:


> Getting back to the "make it better" bit in the original post.
> 
> I think the P-61, with the intrinsic weight and drag added by the (imho) superfluous turret and gunner has the most obvious fix. Since I tend to think that turrets are fighters are nearly always completely superfluous, we could easily improve the Boulton-Paul Defiant and Blackburn Roc by getting rid of that monstrosity in both of them. Of course, the Roc has many more problems, starting with having too little engine.
> 
> ...


Can you expand on the 20mm Hispano idiocy? Really want to know. Thanks.


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## P-39 Expert (Jun 19, 2019)

Please don't think badly of me, the opinions are my own. This is up to mid '44, after that it was a moot point.

P-38 Cancel this thing as soon as possible, use the ones you have for reconnaissance. Too much for the average pilot, too expensive, too low a mach number.
P-39 D through L reduce weight by losing the wing guns and nose armor plate. Move the radios up behind the pilot for balance. Now it will climb with the Zero and still be 40mph faster at all altitudes. Then when the 9.6 engine is available just build the N. If more fuel is needed lose the wing guns and add a fuel tank in each wing. When the two stage Allison -93 starts production in April '43 then start using that. 
P-40 Cancel this one asap too, give the ones already built to our allies. Or make it 1200# lighter somehow. How? No idea. Or re-engine with the F version of the -93 in April '43. 
P-47 Why not just build F8F Bearcats with more internal fuel instead. Almost as fast, much better climb and turn. Common single stage R-2800 engine. Less Expensive.
P-51 The AAF obviously needed to push this plane but initially didn't want them because they were under a British contract. More AAF/Govt politics and bungling? Engine them with Allisons, Merlins, single stage, two stage, just get them into production with the best engine available and constantly upgrade. Get two P-51s for every P-38 or P-47 cancelled.

Of course this is with 20/20 hindsight.


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## swampyankee (Jun 19, 2019)

P-39 Expert said:


> Can you expand on the 20mm Hispano idiocy? Really want to know. Thanks.



AG Williams, of Rapid Fire, has posted an article: Modifications and Attempts at Standardization. Since it's just one source, it may not be fully informative.


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## pbehn (Jun 19, 2019)

P-39 Expert said:


> P-51 The AAF obviously needed to push this plane but initially didn't want them because they were under a British contract. More AAF/Govt politics and bungling? Engine them with Allisons, Merlins, single stage, two stage, just get them into production with the best engine available and constantly upgrade. Get two P-51s for every P-38 or P-47 cancelled.
> .


From what I have read in posts here it would be very difficult to get substantially more of any version, apart from just producing the fighter instead of the A-36 which was political budget thing and a choice of whats best. The AAF didn't have much interest in it even when they got one to test, its a strange story all around.


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## wuzak (Jun 19, 2019)

P-39 Expert said:


> P-47 Why not just build F8F Bearcats with more internal fuel instead. Almost as fast, much better climb and turn. Common single stage R-2800 engine. Less Expensive.



F8F was developed with war experience. If it was developed earlier it would probably end up like the F6F.

Plus the F8F engine didn't exist until 1944?

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## P-39 Expert (Jun 20, 2019)

swampyankee said:


> AG Williams, of Rapid Fire, has posted an article: Modifications and Attempts at Standardization. Since it's just one source, it may not be fully informative.


Very informative, thanks.


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## drgondog (Jun 21, 2019)

P-39 Expert said:


> Please don't think badly of me, the opinions are my own. This is up to mid '44, after that it was a moot point.
> 
> P-38 Cancel this thing as soon as possible, use the ones you have for reconnaissance. Too much for the average pilot, too expensive, too low a mach number.
> P-39 D through L reduce weight by losing the wing guns and nose armor plate. Move the radios up behind the pilot for balance. Now it will climb with the Zero and still be 40mph faster at all altitudes. Then when the 9.6 engine is available just build the N. If more fuel is needed lose the wing guns and add a fuel tank in each wing. When the two stage Allison -93 starts production in April '43 then start using that.
> ...



20/20 hindsight, given the facts of 1939-1941 Doctrine wars within Plans Division, suggest that most of your suggestions were not feasible, and not practical.

First the Politics - Material Command Commanders Spaatz, Brett and Echols were a.) Heavily vested in long range strategic bombardment with belief that the B-17 would always get through opposition interceptors with acceptable losses, and b.) heavily vested in Curtiss first as Pursuit source. Lockheed was newcomer, Seversky built good aircraft but hated Arnold (semi-vocal about it also). NAA regarded as Trainer source, then acknowledged as light/medium bomber and in fact Explicityly excluded from solicitations for Pursuit RFP's.

AWPD-1 reflected bomber centric vision for AAC/AAF Plans but some wiser heads also reminded the senior leadership (Arnold/Emmons) that AAF was part of the Army - and Asst SecWar Lovett reminded Arnold and Emmons of that reality when Arnold became Chief AAF in June 1941. Further he continually reminded both Emmons and Arnold that the dive bomber and fast battlefield recon/fighter force over the battlefield left much to be desired in AAF CAS doctrine. Now look at the timeline. NAA by that time had delivered the XP-51 which was in test and Mustang I production was in swing at that time. NAA initiated design work on the Low Level Pursuit Attack Airplane in October with internal charge number in November. They didn't do so because they wanted to waste R&D funding. NAA was aware of the pressure from Lovett, the tides changing within both Arnold and acolytes in Plans that a.) European experience and Spain were bright posters that the 'bomber might not always get through', and that b.) perhaps they should listen a little harder to USA which very much wanted something better for tactical air support. They got the A-20, the P-39 and P-40 were in play because of their deficiencies as interceptors and reports were dribbling upward regarding the superiority of the XP-51 over P-40E, P-38D, P-39D as low to middle altitude fighter. Ira Eaker, in transit from command of west coast based 20th Interceptor Group stopped by NAA and flew the XP-51 number 2 - and was impressed, noting that the engine was the limiting factor. He informed both Eaker and Arnold of his impressions shortly before being named CO of VIII BC by Spaatz. 

Politics continuing - Oliver Echols was an absolute supporter of Curtiss and pushed the XP-46, third in evaluation of the S/E Pursuit RFP summer/fall 1939, as the Selection. The reports of AFPC dissatisfaction with lack of armor plate and self sealing tanks of existing P-38 and P-39 and P-40 airframes led Echols to craft a strategy to push the XP-46 at Curtiss and off-load the P-40 to NAA to manufacture them to RAF standards including armor and fuel tanks and get Brits to pay for the improvements. NAA raising single digit salute to Echols to pursue the P-509/NA-73X in 1940 made an enemy of Echols and hence Material Command.

This is getting too long but the net of the parallel changes in thinking at AAF HQ, different from Echols/Material Command put NAA in a collision course with Echols, and fortunately General Muir Fairchild, Chief Requirements Div had bigger 'junk' and essentially forced the A-36 down Echols' throat when Echols was championing the Brewster XA-32 as the CAS offering. Nobody in AAF CAS camp thought much of A-25, 25, 31 or 32 as the solution and reports were flooding in that the P-51 was better than the P-39 and P-40 for any role. 

The XP-47B and P-47B were deemed better, at high altitudes, ditto P-38D so they were the Only s/e ac remotely contemplated for escort despite range deficiencies. Neither were ever going to be cancelled then or with 20/20 hindsight 

Everybody realized that the P-39 and P-40 with the same engine were inferior in speed and range and were dead ends relative to future development in mid 1942 but production continued because the tactical requirements globally demanded them. Range was always a huge elephant in the room.

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## GregP (Jun 21, 2019)

First, Hello Bill Marshall! I still want a copy of your next book!

The problems with the P-59 were more involved than what I am reading. We are restoring the 10th YP-59A to flight status and we have many documents.

First, when Bell was asked to produce the jet, they were not told ANYTHING about the engine ... they got a big block of wood and were told the real engines would not be any bigger than the wood form block. But, and here’s the part that most are missing, they were not told how much it would weigh, how much thrust it made, what the fuel consumption was, or where the engine mounts connected to the engines! So, the engine compartment were made too large to accommodate whatever came along as an engine.

So, they made a test-mule airframe with plenty of strong wing, almost a sailplane wing in fact, in case the engines were very heavy. It has air intakes that would do a modern jet engine proud, as far as area and air volume went, but the engines they got didn’t need anywhere NEAR that much inlet area. So, a good deal of the inlet air would go in, turn static, and bleed back out around the intake mouth, creating or helping to create directional instability. They COULD have done things differently, but the US Government wasn’t very big on sharing data such as the amount of intake air required at the time. Probably, they really didn't know.

We have a flight test report on our aircraft!

The plane we have has engines that burn about 575 gallons per hour combined at low altitudes. It has less than 300 gallons of fuel, excluding the extra fuel tanks. Good luck with the range! It needs auxiliary tanks to have enough fuel to get around the pattern more than two or three times! The fuel consumption could be made to drop, but you’d use up the internal fuel just climbing up to any decent height making the extended climb a thing to avoid.

If you DID get above 35,000 feet, the canopy would freeze over from the inside! If you open the canopy in flight, you can’t get it closed! The roll rate was VERY slow, and would have been difficult to improve. The aileron gap seals were quite long (and still are), and the ailerons only had about 11° - 13° of movement in them at full deflection! The aileron tabs were servo tabs ... we have changed them to anti-servo tabs to get maybe a bit more roll rate at the expense of a slightly heavier stick. Our plane will be an airshow machine only, and it won’t ever go very fast.

While the P-59 may not have been a very good airplane, it DID serve to introduce many WWII-era piston pilots to jet engines. And therein lies it’s worth. The first squadrons of P-80 pilots were all transitioned from P-59 Airacomets, so they did their bit for us when they were in service.

We have had several pilots come through the Planes of Fame who flew the P-59 in one of it’s forms, and at least 2 who flew our bird (tail number 777). More than one has said he ran out of fuel regularly when flying a P-59 and it glided well enough to get to any of several fields, where they would land, call home for fuel, and go to the nearest bar to wait for said fuel. We tend to forget that when they were flying the P-59 Airacomet, jet fuel was not standard at ANY airfield. You called for it and waited for the truck to show up. Might as well have a drink meanwhile!

There is NOTHING on the YP-59A that is easy to work on, and changing engines is not a fun task. But you would have to do exactly that at relatively short intervals. TBO on the early engines was only a bit north of 20 hours! Altogether, the YP-59A is a very interesting piece of aeronautical history that I hope to see fly within a couple of years. There are several generations of restoration volunteers who are eagerly awaiting daylight under the tires due to changing jet fuel into noise.

We think one of the I-16 engines makes about 1,600 pounds of thrust … and the other one just makes noise! Not really, but is sure seems that way! 12,500 pounds of aircraft and 3,200 pounds of thrust don't exactly make it "sprightly!" We just hope we don't destroy the fabric-covered elevators with flames from startup due to overflowing raw fuel into the bottom of the combustion chambers! So, we will have an item on our checklist to keep the stick full aft during startup! Heck, the engine igniters are a pair of old Ford "shower of sparks" units that fire a pair of spark plugs!

Cheers.

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## Zipper730 (Jun 22, 2019)

drgondog said:


> fortunately General Muir Fairchild, Chief Requirements Div had bigger 'junk' and essentially forced the A-36 down Echols' throat when Echols was championing the Brewster XA-32 as the CAS offering.


Wasn't the XA-32 a lemon?


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## fubar57 (Jun 22, 2019)

A husky brute of an attack plane, the XA-32 was terribly overweight at almost 20,000 pounds. The drag induced by its rotund shape was amplified by careless detail design, which left it festooned with bumps and lumps. It was underpowered by the Pratt and Whitney R-2800. The real problem, however, was that the XA-32 suffered from the terminally bad Brewster management system. First flight was not until 22 May 1943, two years after the design was proposed; and almost every aspect of performance fell short of the specifications. The firm was in such management shambles that it drew the wrath of Congress and actually went out of the aircraft manufacturing business. Only two examples built. 

Brewster XA-32 Info​

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## swampyankee (Jun 22, 2019)

Having worked in a classified project, I found it amazing what the military found necessary to classify. At the time, among other things that were classified were some of the computer programs, which were based on standard textbooks and readily available technical publications, many of which were from the USSR (there were a lot of articles from the Soviet equivalent of IEEE and APS; it was ironic that Cold War era stealth technology was so reliant on Soviet sources).


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## GrauGeist (Jun 22, 2019)

In regards to Brewster amd their terrible production and quality control:
The company was not only mismanaged, but had poorly trained employees and disgruntled union members, who went on strike several times (which was illegal during wartime). The Navy stepped in, took control of the company in '42, but that didn't help things much.

Add to that, the Brewster's original manufacturing plant, which was an old auto manufacturing facility that was poorly suited for producing aircraft - in otherwords, as a plane was being manufactured, it had to be disassembled enough to move it to the next floor, reassembled and production continued until it needed to be moved to the next stage of assembly, which it then had to be partially disassembled in order to be moved along. Then they had to be shipped about 50 miles to the airfield, where they were finalized for delivery to the USN. This did not help the quality control nor was it very efficient time-wise.

An example of how bad things were; the Navy, after cancelling the Buccaneer contract, removed more than three hundred airframes from the plant and directly scrapped them.

It was just one great big mess all the way around.

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## swampyankee (Jun 22, 2019)

Brewster is one of a (what's the antonym of elite?) small group of defense companies that managed to go out of business during wartime. This sort of management brilliance was probably not included in any MBA program as analyzing failure is not something those guys do.

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## Zipper730 (Jun 22, 2019)

swampyankee said:


> Having worked in a classified project, I found it amazing what the military found necessary to classify. At the time, among other things that were classified were some of the computer programs, which were based on standard textbooks and readily available technical publications, many of which were from the USSR (there were a lot of articles from the Soviet equivalent of IEEE and APS; it was ironic that Cold War era stealth technology was so reliant on Soviet sources).


Weird that they'd classify things that are publicly available.

It is ironic that much of the knowledge of stealth came from the former Soviet Union. From what I recall, the problem was that they had trouble creating shapes that were stealthy that could also be made compatible with shapes that can fly.


swampyankee said:


> what's the antonym of elite?


Dregs...


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## Zipper730 (Jun 22, 2019)

GregP said:


> First, when Bell was asked to produce the jet, they were not told ANYTHING about the engine ... they got a big block of wood and were told the real engines would not be any bigger than the wood form block. But, and here’s the part that most are missing, they were not told how much it would weigh, how much thrust it made, what the fuel consumption was, or where the engine mounts connected to the engines!


How does one design an airplane around that? It's vital to know about the propulsion system. The intakes have to be designed around how much airflow goes into them, while I am not hugely knowledgeable on reciprocating engines (despite them powering pretty much every single car on the road), you would assume the carburetor & radiator intakes would be sensitive to these issues (though I could be wrong).

It's one thing when you're building a bomber to carry a nuclear bomb: The bomb is usually carried on the center of gravity (that said, you'd still want decent figures for weight), and you can fly without it.


> They COULD have done things differently


Could you give an example of how?


> the US Government wasn’t very big on sharing data such as the amount of intake air required at the time. Probably, they really didn't know.


I'm curious how the UK handled this matter? I know they developed a propulsion testbed (E.28/39) and the Gloster Meteor, of which both had jet-engines.


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## Kevin J (Jun 22, 2019)

Zipper730 said:


> How does one design an airplane around that? It's vital to know about the propulsion system. The intakes have to be designed around how much airflow goes into them, while I am not hugely knowledgeable on reciprocating engines (despite them powering pretty much every single car on the road), you would assume the carburetor & radiator intakes would be sensitive to these issues (though I could be wrong).
> 
> It's one thing when you're building a bomber to carry a nuclear bomb: The bomb is usually carried on the center of gravity (that said, you'd still want decent figures for weight), and you can fly without it.
> Could you give an example of how?
> I'm curious how the UK handled this matter? I know they developed a propulsion testbed (E.28/39) and the Gloster Meteor, of which both had jet-engines.


 The Meteor could handle whatever turbojets or turboprops were becoming available.


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## Zipper730 (Jun 22, 2019)

Kevin J said:


> The Meteor could handle whatever turbojets or turboprops were becoming available.


So, the problem was that the RAF was telling the company what engines existed and more capability about what they could and could not do?

That and the engines were mounted on the wings in pods that could be more easily changed...

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## davparlr (Jun 22, 2019)

Hey, Greg, how are you guys doing? I heard there was some rocking and rolling in your neck of the woods.

Broke my heart to hear about the crash of the N-9M and loss of the pilot.



GregP said:


> The problems with the P-59 were more involved than what I am reading. We are restoring the 10th YP-59A to flight status and we have many documents.



It always is



> First, when Bell was asked to produce the jet, they were not told ANYTHING about the engine ... they got a big block of wood and were told the real engines would not be any bigger than the wood form block. But, and here’s the part that most are missing, they were not told how much it would weigh, how much thrust it made, what the fuel consumption was, or where the engine mounts connected to the engines! So, the engine compartment were made too large to accommodate whatever came along as an engine.



It is amazing that the military would foolishly not keep Bell updated on progress of the jet engine. An imbedded Bell engineer should have been keeping the aircraft engineers updated on the latest evolution of the I-16 engine.



> The plane we have has engines that burn about 575 gallons per hour combined at low altitudes. It has less than 300 gallons of fuel, excluding the extra fuel tanks. Good luck with the range! It needs auxiliary tanks to have enough fuel to get around the pattern more than two or three times! The fuel consumption could be made to drop, but you’d use up the internal fuel just climbing up to any decent height making the extended climb a thing to avoid.



A comparison here of the YP-59A to the XP-80 (which flew a year later) is interesting and also the P-59B and the P-80A (both flown by end of war)

YP-59A
Gross weight 10,532 lb
Fuel Quantity 290 gallons
Engine/s two GE I-16 1600 lbs thrust, 3,200 lb total
Specific Fuel Consumption (SFC) 1.23
Top Speed 409 mph at 35,000 ft
Service Ceiling 43,200 ft

XP-80
Gross weight 8,916 lbs
Fuel Quantity 200-285 gallons
Engine one De Havilland Goblin H-1 total thrust 2,460 lbs
SFC 1.23
Top Speed 502 at 20,000 ft.
Service ceiling 41,800 ft.

As you can see here there is a slight difference between these two. The P-59 is slightly heavier but with 30% more thrust and a slightly higher ceiling. It also has more fuel. However, it is 100 mph slower. Fuel consumption (SFC) is identical, however the more powerful P-59 engines would use more fuel especially since the plane was very draggy.

P-59B
Gross weight 11,040 lbs
Fuel Quantity 365 gallons
Engine two GE J-31 (I-20) 2000 lb thrust each 4,000 lb total
Engine weight 902 lbs, total 1804
SFC 1.2
Top speed 413 mph at 30,000 ft
Service ceiling 46,200

P-80A
Gross weight 11,700 lbs
Fuel quantity 470 gallons
Engine one Allison J33 4,000 lb thrust total
Engine weight 1,850 lbs
SFC 1.19
Top Speed 558 mph at SL, 508 at 30,000 ft
Service ceiling 45,000 ft.

These two planes are also similar, similar weight and thrust and SFC. P-80 has almost 30% more fuel. Again, the P-80 is almost 100 mph faster at 30,000 ft. probably more at SL. Fuel consumption was an issue on all the early jet engines. Its obvious that the main issue is the drag on the P-59, mainly due to the wing design.



> If you DID get above 35,000 feet, the canopy would freeze over from the inside! If you open the canopy in flight, you can’t get it closed! The roll rate was VERY slow, and would have been difficult to improve. The aileron gap seals were quite long (and still are), and the ailerons only had about 11° - 13° of movement in them at full deflection! The aileron tabs were servo tabs ... we have changed them to anti-servo tabs to get maybe a bit more roll rate at the expense of a slightly heavier stick. Our plane will be an airshow machine only, and it won’t ever go very fast.



Except for the canopy, my new wing would fix this.




> There is NOTHING on the YP-59A that is easy to work on, and changing engines is not a fun task.



I suspect product schedule pressure negated desire to build to maintainability.

Overall, I suspect all of these issues could be address successfully and time to do so if there was a desire. However, in 1942-43, I think there was a general apathy in the US to work jet issues. In 1944 with the advent of the Me 262, priorities changed. The AAF did not want to fix an old and slow airplane, they wanted a new one, and they got a good one.


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## Zipper730 (Jun 22, 2019)

davparlr said:


> It is amazing that the military would foolishly not keep Bell updated on progress of the jet engine.


I'd say so, especially when you consider that we started developing a jet engine because the British and Germans were developing the designs. In other words, we were behind the curve, so that means we don't have to keep as many secrets as say, the UK or Germans, because they were ahead of the curve.


> An imbedded Bell engineer should have been keeping the aircraft engineers updated on the latest evolution of the I-16 engine.


When you say that, you mean the engineer would be specially briefed and "read in", and he would be allowed to give data as needed?


> I suspect product schedule pressure negated desire to build to maintainability.


The P-59 served two purposes, as I understand it: Firstly, to be a proof of concept for jet powered aircraft/fighters; secondly: To be a functional jet fighter.

It at least met the first goal, and it flew fast enough to show the benefit of jet-engines (375 mph IIRC 1 lbf = 1hp)


> Overall, I suspect all of these issues could be address successfully and time to do so if there was a desire. However, in 1942-43, I think there was a general apathy in the US to work jet issues.


I always found that surprising...


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## P-39 Expert (Jun 24, 2019)

Supposednly the engines didn't deliver the advertised thrust also.


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## Shortround6 (Jun 24, 2019)

davparlr said:


> I think there was a general apathy in the US to work jet issues



I am not sure about that given the total number of engine projects being worked on. However some of them never produced working hardware (or at least worked well enough to get off the test bench) so the effort gets a bit short changed in many popular histories. 

Nathan Price started work in 1938, he went to work for Lockheed but the over ambitious L-1000 engine sucked up a lot of time for little result.

Vladimir Pavlecka had gone to work for Northrop in 1939 with the idea of developing a turbo prop, they got money from both the army and navy in 1941. 

The NACA was fooling around with ducted fans.

By Sept 1941 GE had to projects going, the Whittle type engines at Lynn and an axial flow turbo prop at Schenectady. 

P&W had started work on 5000hp turbo prop in May of 1941. They stopped work in June 1945 after spending 3.3 million dollars.

Allis-Chalmers was involved in several projects but they led to no real practical results (they may have been the Brewster of Jet engines)

Westinghouse got contracts to build a jet engine (axial) in Jan 1942. 

One thing (out of a number of things) that hindered US progress was the Army's insistence that everything be top secret. So much so that the two GE programs were not allowed to talk to each other let alone any company talk to another company. There was a lot of needless duplication of effort in things like burner cans, igniters, bearings and lubrication, fuel management and so on.


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## Zipper730 (Jun 24, 2019)

Shortround6 said:


> I am not sure about that given the total number of engine projects being worked on. However some of them never produced working hardware (or at least worked well enough to get off the test bench) so the effort gets a bit short changed in many popular histories.


True


> Nathan Price started work in 1938, he went to work for Lockheed but the over ambitious L-1000 engine sucked up a lot of time for little result.


I'm amazed at the overly complex nature of the engine. It was too complex to begin with, and became increasingly absurd around requirements that weren't necessary for the engine

They either miscalculated the efficiency of the engine, were trying to get more power than they really needed, or both
The earliest design had an axial flow compressor feeding a reciprocating compressor, with an afterburner: It didn't seem to go far
The second design incorporated a mixed-flow arrangement
The reciprocating compressor was replaced with a three-staged centrifugal-flow section
The first compressor stage was variable-pitched in configuration
Intercooling was placed between the axial and centrifugal compressors; provision also existed for intercooling between at at least two of the three centrifugal flow stages.
The engines were "handed" something that's not needed in jets
The engines were fitted with a differential gearing and hydraulic coupling to allow the adjustment of the RPM, so it can operate a boundary-layer control system. I'm not sure if this was something Mr. Price was looking at himself, or Lockheed took a serious interest in.

The third design incorporated a twin-spool arrangement
32-stages of compressor blades divided across two 16-stage shafts
The first four blades on the LP shaft was effectively hydraulically clutched
Intercooling was retained, and positioned between the LP & HP shafts
The engine was now fitted with an annular combustion chamber
The afterburner used a regeneratively cooled configuration from what I remember


They designed the engines around qualities that might not have been planned in the aircraft, such as laminar flow control
They seemed to not quite factor in the fact that fuel burn drops quite a bit as you go higher, and ram-compression adds quite a bit of performance to the engine



> Vladimir Pavlecka had gone to work for Northrop in 1939 with the idea of developing a turboprop, they got money from both the army and navy in 1941.


Still an improvement over a piston driven engine. His design was axial flow, and would have easily laid the way for turbojet development.


> The NACA was fooling around with ducted fans.


They really had a predilection for that over a turbojet. They seemed to be preoccupied with that over a gas-turbine. Fro what I remember, the rationale was as follows

Edgar Buckingham's Report: It wasn't about a gas-turbine, but about a piston engine producing all it's power in the form of thrust instead of driving a propeller
His expectations were for exhaust-velocities as high as 5280 fps: Higher exhaust velocities work terribly at lower speeds and, while I don't know the exhaust stack airflow velocity, considering that 375 mph results in 1 hp / 1 lbf: I would be lead to assume that the velocities would be similar to gas-turbines
His expectations called for pressure-ratios of around 15-30, which would hinge upon gear-driven or exhaust-driven superchargers: Most early jet-engines had pressure ratios that were around 3.5-4.0. I'm not sure when we would see pressure ratios of 15-30 to 1.
While he factored in ram-compression reducing the required engine-size: He did not factor in speeds above 250 mph, and speeds of that figure were already being approached, reached, or exceeded in 1923.

Gas-turbines were believed to be grossly overweight: This seemed to have not been understood as well as it should be -- it seems many steam turbines were big because they were designed for power-generation, not an inherent fault in the design of the engine.



> One thing (out of a number of things) that hindered US progress was the Army's insistence that everything be top secret. So much so that the two GE programs were not allowed to talk to each other let alone any company talk to another company. There was a lot of needless duplication of effort in things like burner cans, igniters, bearings and lubrication, fuel management and so on.


The problem is how does one balance secrecy, with the ability to coordinate efforts? You'd think there'd be some guy who's in charge of everything and he manages all the projects.


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## GrauGeist (Jun 24, 2019)

Shortround6 said:


> One thing (out of a number of things) that hindered US progress was the Army's insistence that everything be top secret. So much so that the two GE programs were not allowed to talk to each other let alone any company talk to another company. There was a lot of needless duplication of effort in things like burner cans, igniters, bearings and lubrication, fuel management and so on.


Which is one of the reasons the P-59A was never able to live up to it's full potential. It was literally built around an imaginary engine (as Greg noted) and so it had considerable flaws as a result.
The interesting fact here, is that the P-59A first flew in October 1942 - just a few months after the Me262 (V3) first flew under jet power - and almost 6 months before the Meteor first flew.
And *if* the Army had dropped all the cloak & dagger stuff and been a little more forthcoming with the engine details, the Airacomet may have not only been able to perform better, but it's teething troubles would have been far lesser resulting in a shorter maturation time and it most likely could have been seen in Europe's skies as a result.

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## Mad Dog (Jun 25, 2019)

Shortround6 said:


> ….The .5in Vickers was large, heavy and suffered from jams even though it rarely actually broke. (How do you define reliability?) it also didn't have a particularly high rate of fire. Provision of truly effective ammo was a problem, No HE rounds and good incendiaries only came later?....


 For the Army, the sole reason for the Vickers .5 was to provide a punchier companion to the Vickers .303, and firing only AP ammo. There was no driver to produce a SAPI round as far as the Army was concerned. The Royal Navy did have a reason as they used the Vickers .5 in quad mountings as a close-in air defence weapon, but they decided to upgrade to the Oerlikon 20mm cannon instead. The RN also used a SAP round as it was almost as effective as the AP round and cheaper to make. Kynoch had developed a SAP-T round in 1935 but the MoD didn't buy it for the Army, but the RN did. Rate of fire was 750rpm, which was higher than the Hispano.
If the RAF had decided to go with the air-cooled Vickers .5 in the '30s, then they could have quite easily scaled up the existing .303 incendiary and tracers, and produced a de Wilde/Dixon SAPI round in 1940. Which suggest the RAF could easily have had an air-cooled Vickers .5 version, firing HE, SAPI, SAP and SAP-T in time for the Battle of Britain. They could even have copied the Italian .5 HE bullet seeing as the Italian round was a Vickers modification of their .5 round, or scaled up the .303 HE rounds like the Pomeroy type. Good info on actual Vickers .5 ammo here and info on the Vickers here


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## PAT303 (Jun 25, 2019)

Mad Dog said:


> For the Army, the sole reason for the Vickers .5 was to provide a punchier companion to the Vickers .303, and firing only AP ammo. There was no driver to produce a SAPI round as far as the Army was concerned. The Royal Navy did have a reason as they used the Vickers .5 in quad mountings as a close-in air defence weapon, but they decided to upgrade to the Oerlikon 20mm cannon instead. The RN also used a SAP round as it was almost as effective as the AP round and cheaper to make. Kynoch had developed a SAP-T round in 1935 but the MoD didn't buy it for the Army, but the RN did. Rate of fire was 750rpm, which was higher than the Hispano.
> If the RAF had decided to go with the air-cooled Vickers .5 in the '30s, then they could have quite easily scaled up the existing .303 incendiary and tracers, and produced a de Wilde/Dixon SAPI round in 1940. Which suggest the RAF could easily have had an air-cooled Vickers .5 version, firing HE, SAPI, SAP and SAP-T in time for the Battle of Britain. They could even have copied the Italian .5 HE bullet seeing as the Italian round was a Vickers modification of their .5 round, or scaled up the .303 HE rounds like the Pomeroy type. Good info on actual Vickers .5 ammo here and info on the Vickers here



Your forgetting the biggest issue with aircraft weapons which is how they perform once installed and under G load. Look at the Hispano and Browning .50 as examples, on a fixed mount both worked perfectly, in a twisting wing under G load both fared poorly, the RAF used .303 brownings because they worked all the time every time throughout the war, the Hispano and BMG were more effective weapons but both required lots of debugging before they got there, there's nothing to suggest the .5 Vickers would be any different. Interesting enough both the .50's ended up using scaled up versions of .303 ammunition which means fighting the BoB with cup and core ball ammo if they were adopted, in my opinion it would have been better to stick with what works, the .303 brownings and devote time and money in producing more specialised De-Wilde/Dixon/AP ammunition than a whole new gun system.

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## Shortround6 (Jun 25, 2019)

The trouble with the .5in Vickers was that it was a Vickers, with all the good and bad that came with it. Vickers guns are reputed to break very seldom and last for tens of thousands of rounds (if not hundreds of thousands given barrel changes) but are subject to a large variety of jams/malfunctions, most of which can be cleared quickly if the gunner has access to the gun which in a wing mount he does not. This was the impetus for adopting the Browning, getting a gun that could be mounted away from the pilot or crew. There is no reason to believe the Big Vickers would be any better than the small Vickers in this regard and indeed a few tales from the Royal Armoured Corp with .5in Vickers in one man turrets suggest that the gun was harder to work on than the smaller gun due to the confined space. 

the 2nd problem with the Vickers is that for some reason it had a lower rate of fire than the Brownings. The best they got out of a rifle caliber Vickers seems to be about 900rpm with synchronization while the small Browning could hit 1200rpm (or higher in experiments), The best out of the Big Vickers seems to be 700rpm? The Japanese got 900rpm out of their Browning copy (unsynchronized) and the Americans got 800rpm or better from the M2 in late 1940 or early 41. 

Firing AP bullets the numbers don't look good for the big Vickers. since you can mount two .303 Brownings for the weight of a single .5in Vickers (?) the two Brownings can deliver 448 grams of projectiles per second (40 bullets) vs the 424 grams or less for the .5in Vickers (figured 12 bullets per second/720rpm) The .50 Browning used significantly heavier bullets than the .5in Vickers. 
We can try comparing the amount of incendiary material thrown another time but you need to push the firing rate of the gun (of whatever action) using the .5 Vickers ammo to 900rpm to get even an 18% increase in throw weight over the pair of .303 Brownings (which are still lighter and use lighter Ammo. ) how much of an improvement do you need to make a change?


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## P-39 Expert (Jun 26, 2019)

Shortround6 said:


> The trouble with the .5in Vickers was that it was a Vickers, with all the good and bad that came with it. Vickers guns are reputed to break very seldom and last for tens of thousands of rounds (if not hundreds of thousands given barrel changes) but are subject to a large variety of jams/malfunctions, most of which can be cleared quickly if the gunner has access to the gun which in a wing mount he does not. This was the impetus for adopting the Browning, getting a gun that could be mounted away from the pilot or crew. There is no reason to believe the Big Vickers would be any better than the small Vickers in this regard and indeed a few tales from the Royal Armoured Corp with .5in Vickers in one man turrets suggest that the gun was harder to work on than the smaller gun due to the confined space.
> 
> the 2nd problem with the Vickers is that for some reason it had a lower rate of fire than the Brownings. The best they got out of a rifle caliber Vickers seems to be about 900rpm with synchronization while the small Browning could hit 1200rpm (or higher in experiments), The best out of the Big Vickers seems to be 700rpm? The Japanese got 900rpm out of their Browning copy (unsynchronized) and the Americans got 800rpm or better from the M2 in late 1940 or early 41.
> 
> ...


You have mentioned before how the Browning .50 improved throughout the war, could you point me to a post that summarizes that? Is that why often the rate of fire is quoted as a range (600-720)? How much did synchronization through the propeller reduce the rate of fire? Thanks.


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## swampyankee (Jun 26, 2019)

P-39 Expert said:


> You have mentioned before how the Browning .50 improved throughout the war, could you point me to a post that summarizes that? Is that why often the rate of fire is quoted as a range (600-720)? How much did synchronization through the propeller reduce the rate of fire? Thanks.



According to Tony Williams "tests of cowling-mounted .50M2 in US aircraft revealed RoFs of 400–450 rpm " http://www.quarryhs.co.uk/Synchro.pdf

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## Shortround6 (Jun 26, 2019)

P-39 Expert said:


> You have mentioned before how the Browning .50 improved throughout the war, could you point me to a post that summarizes that? Is that why often the rate of fire is quoted as a range (600-720)? How much did synchronization through the propeller reduce the rate of fire? Thanks.




actually the early guns (up to some point in 1940) fired at 500-600rpm, this is with short belts and on a test stand with no extra G's causing extra belt drag. The rate of fire was boosted to 750-850rpm at some point in 1940, I don't know what month. The older guns could be brought up to the new standard with a parts kit. At some point they changed the feed cam trackway and doubled the amount of pull the gun exerted on the belt to help with some of the feed problems. All guns fired over a range as even guns built hours apart on the same production line have slightly different weight bolts, different "fit" (even a few thousands of in inch difference in clearance) and slightly different strength springs. 

As shown in the link provided by Swampyankee synchronization could affect some guns more than others but the Browning .50 seemed particularly affected. 
The other major change was that the ammo changed right before the war and then the provision of different bullets during the war.

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## P-39 Expert (Jun 26, 2019)

Thanks for the info. So from about 1941 through the rest of WWII the .50 remained about the same?


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## davparlr (Jun 26, 2019)

Shortround6 said:


> I am not sure about that given the total number of engine projects being worked on. However some of them never produced working hardware (or at least worked well enough to get off the test bench) so the effort gets a bit short changed in many popular histories.


Perhaps I should have said "jet aircraft" issues. They had originally designed the P-59 to be upgraded to a fighter, better than projected prop jobs. They knew immediately that the plane was not capable of that yet they seemed not to be particularly interested in upgrading performance, like replacing the wing. The Me 262 had flown only a few months ahead of the P-59 but was still able to make significant changes (like getting the main landing gear behind the center of gravity, gotta be major wing modification, and installing a nose gear, another major modification) and addressing the various propulsion issues that all had to face in the early days, and still make combat in spring of '44. The Germans did have an advantage of knowing what they wanted out of a jet plane and had more expertise behind them. Still determining why the plane was such a poor performer and fixing it didn't seem to fit the equations (it had more thrust available than the 100 mph faster He 280). I think the general philosophy of the military at this time was "better is the enemy of good enough" and in 1942 they had designs that were good enough and didn't stress fixing the P-59 (maybe also affecting the design of the T-26 tank and larger bazooka, and others) . Secrecy may have played into this however redesigning the wing would not have been a problem, allocated money may have been. I still think they might have slapped on the P-63 wing and gotten significantly better performance.
There just didn't seem to be pressure to make it work as there was in Germany, and England.


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## Shortround6 (Jun 26, 2019)

P-39 Expert said:


> Thanks for the info. So from about 1941 through the rest of WWII the .50 remained about the same?


For all practical purposes yes, for winning bar bets no.

The US was trying desperately to raise the rate of fire to 1200rpm or so, several different manufacturers involved with many different model guns. US Ordnance was unwilling to relax the reliability standards (number of stoppages and broken parts per 5,000 rounds) By late 1944 they got near to what they wanted and around 8,000 guns were built using a "T" number. this was standardized as the M3 gun but very few saw combat. You could not turn an M2 into an M3 with a parts kit., one of the original requirements. The receiver itself needed to be modified. The M3 did see widespread use in the Korean war. 

The US also introduced the M8API round in late 43 or 44 to cut down on the mixed belts of AP and separate incendiary rounds. 
What would become the M23 incendiary round was also developed and tried/trialed in combat during WW II but with limited success. The bullet used a much thinner tube (or just used the bullet jacket itself to contain the incendiary mixture) so it carried much more incendiary mixture than other .50 incendiary bullets and the lighter weight allowed higher velocity. However the light jacket may have been the source of premature ignition (sometimes in the gun barrel and all to often right in front of the gun barrels.
Several small redesigns and at least two changes of manufacturer in an attempt to improve quality control saw the M23 round being used in considerable numbers in Korea. 

This is from memory so a few details might be off but that is the general story of development from 1941/42 on.

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## P-39 Expert (Jun 27, 2019)

Shortround6 said:


> For all practical purposes yes, for winning bar bets no.
> 
> The US was trying desperately to raise the rate of fire to 1200rpm or so, several different manufacturers involved with many different model guns. US Ordnance was unwilling to relax the reliability standards (number of stoppages and broken parts per 5,000 rounds) By late 1944 they got near to what they wanted and around 8,000 guns were built using a "T" number. this was standardized as the M3 gun but very few saw combat. You could not turn an M2 into an M3 with a parts kit., one of the original requirements. The receiver itself needed to be modified. The M3 did see widespread use in the Korean war.
> 
> ...


Thanks.


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## Thos9 (Jun 27, 2019)

Ivan1GFP said:


> I believe the Mitsubishi A6M Type 0 would have done quite a bit better if the initial design had gone with the Mitsubishi Kinsei engine instead of the Nakajima Sakae. It may not have had quite the same range and agility, but would have stayed as a viable fighter for much longer.
> The Japanese eventually came to the same conclusion when they fitted the Kinsei to the A6M8 but it might have been a whole lot better if it had been done 5 years earlier.
> 
> I also believe that the FW 190 series should have gotten an increase in the size of its wing. In the prototype stage, it had already gone from a 160 ft^2 wing to 197 ft^2 wing but weight increased substantially with production models and the size of the wing did not change. It also meant that if not properly flown, it had a tendency to
> ...


The FW190A-6 of early 1943 actually had a new wing of lighter construction but very similar (not identical)dimensions th the A-5. Instead a larger wing should have been adopted as you suggest. The A-10 projected in October 1943 but apparently not built would have had a larger wing of 37'8'' and 220 square feet.

For other A series improvements
- change the supercharger drive to hydraulic constant boost a la DB engines
- fit MW and uprated 801 engines as available (E, TS, F )
- remove all guns and ammunition from the fuselage to the wings
- fit an MW tank in place of the fuselage guns
- extend the forward fuel tank forward to the main spar in place of the inner cannon mags
- extend the aft fuel tank upwards behind the pilot a la Bf 109
- allow for wing radiators and a liquid-cooled engine (DB603 or Jumo 213) in a streamlined nose with better downward vision and sighting
- fit an EZ42 or 45 gyro sight as available
- allow for 4 MG213A guns in 20mm or 24mm versions as available
- fit wing fuel tanks as space allows.


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## tomo pauk (Jun 27, 2019)

Thos9 said:


> The FW190A-6 of early 1943 actually had a new wing of lighter construction but very similar (not identical)dimensions th the A-5.
> ...



A lighter wing on the A-6 - interesting. Care to share some good data/sources on it?



> For other A series improvements
> - change the supercharger drive to hydraulic constant boost a la DB engines



Why would we do it?



> - fit MW and uprated 801 engines as available (E, TS, F )



Yes, the 801E was much improved engine, especially of note being it's supercharger.



> - remove all guns and ammunition from the fuselage to the wings
> - fit an MW tank in place of the fuselage guns



I'd indeed remove fuselage guns & their ammo. OTOH, cannon ammo between the engine and all of fuselage internals was protected from enemy fire - relocating that ammo to wing warrants armor plating it.
BMW 801 was not in dire need for MW 50 - C3 fuel gave anything needed down low, while there was not much worth of supercharging at high altitudes to matter for MW 50.



> - extend the forward fuel tank forward to the main spar in place of the inner cannon mags
> - extend the aft fuel tank upwards behind the pilot a la Bf 109
> - fit wing fuel tanks as space allows.



All of that likely doubles the internal fuel tankage. All good an well, but a much better engine is now needed to provide performance.



> - allow for wing radiators and a liquid-cooled engine (DB603 or Jumo 213) in a streamlined nose with better downward vision and sighting



Just having 603 or 213 instaled as-is by late 1943 improves things by a large margin. Wing radiators will clash with undercarriage legs, and/or with guns/ammo/new fuel tanks?


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## Zipper730 (Jun 28, 2019)

I remember reading about the P-39's carburetor intake having almost no ram-compression benefit: Could some kind of bifurcated layout have worked? I remember it being used on the F4U and it provided decent ram-compression...


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## Thos9 (Jun 28, 2019)

tomo pauk said:


> A lighter wing on the A-6 - interesting. Care to share some good data/sources on it?
> An article by William Green in Flying Review International in my library which is in NZ and I in France until August - I will look it out then and post.
> Why would we do it?
> 
> ...


No clash with u/c or guns/ammo. Radiators would displace some potential tankage. An aircooled engine had advantages esp re vulnerability and in Jabo role.

[


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## P-39 Expert (Jun 28, 2019)

Zipper730 said:


> I remember reading about the P-39's carburetor intake having almost no ram-compression benefit: Could some kind of bifurcated layout have worked? I remember it being used on the F4U and it provided decent ram-compression...


The P-63 had a more streamlined carb intake with a boundary layer splitter. Should have been easily adapted to a P-39.


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## Shortround6 (Jun 28, 2019)

Guys, see : http://www.wwiiaircraftperformance.org/P-39/P-39D_41-6722_PHQ-M-19-1325-A.pdf 

In level flight at over 360mph (plane hit 368mph) the P-39D could hold 1150hp to 13,800ft.
When climbing at about 190mph it could hold 1150hp to 12,400hp.

Allison rated the engine at 1150hp at 12,000ft no RAM so obviously some RAM was being generated in level flight. At a higher angle of attack, like when climbing, perhaps the canopy did mask the intake some what. Or perhaps the P-40 system was better but obviously picking up 1800ft of altitude shows that the claim of "almost no ram-compression benefit " is false.


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## tomo pauk (Jun 30, 2019)

Thos9 said:


> An article by William Green in Flying Review International in my library which is in NZ and I in France until August - I will look it out then and post.



Okay, thanks in advance



> First - hydraulic drive maintains constant boost (and hence steadily increasing performance) up to critical altitude, whereas a mechanical two-speed delivers falling boost and performance up to speed-change altitude. That is why the Grumman F8F-2 used the R2800-30 replacing the -22 and -34 and reached 447mph at 26,000 feet.



Hydraulic drive also 'steals' power at lower altitudes (not just due to the slip), adds up to oil cooling requirement, and does nothing above the rated altitude. Fw 190 was already excellent under 20000 ft, it needed a much improved altitude power above 20000 ft once P-47s (and especially Merlin Mustangs) came in knocking. Better spend resources to make a better S/C.
The R-2800-30 was an E series engine, vs. -22 and -34 being C series engine - post war vs. wartime. Apart from internals being modified and improved, it also spinned it's (better? bigger? both?) S/C at up to 10.55 times the crankshaft rotation speed, while the -22 and -34 were doing it at max 9.45 times the crankshaft speed. Faster S/C means better altitude power, that usually means greater speed.



> Second - the 801D and E both had a critical altitude of 18,700 feet (D 1,440hp, E/TS 1700hp) and the target set operated upwards of 25,000 feet. The DB603E had a critical altitude of 23,000 feet (1,550hp - 1,900 at 18,000 with MW).



The DB 603E can't help in 1943, it was a rare engine even in 1944. It's good altitude power was not a fruit of having a hydraulic drive, but rather of great displacement, good RPM for that displacement, and improved S/C.



> C3 (96-100 octane) was from mid 1944 up against 150 octane down low. With hydraulic drive the 801 would profit from MW up to 20K or more -its supercharger was of 331mm diameter cf 320 for the 603E.



C3 in 1944 was more or less equal to the Allied 130 grade fuel. Again, Fw 190 does not need help under 15000 ft, or even under 20000 ft, it was above 20000 ft when it start loosing the war for Germany in the ETO.
Problem with impeller of the S/C on the BMW 801A/C/D was not size, but inefficiency (a problem compounded by the restrictive internal intakes) - the E and S with newly designed S/C gained 15-20% increase of power on same boost.



> No clash with u/c or guns/ammo. Radiators would displace some potential tankage. An aircooled engine had advantages esp re vulnerability and in Jabo role.



Wing radiators of the type we see on Spitfires and Bf 109s are inferior to annular radiators.

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## P-39 Expert (Jul 1, 2019)

tomo pauk said:


> Okay, thanks in advance
> 
> 
> 
> ...


Why are wing radiators inferior to annular? Just asking.


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## tomo pauk (Jul 1, 2019)

P-39 Expert said:


> Why are wing radiators inferior to annular? Just asking.



As designed on Spitfire and Bf 109, they were draggier than annular radiators. Plus, they add more length or tubes, meaning increase of vulnerable area.


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## swampyankee (Jul 1, 2019)

P-39 Expert said:


> Why are wing radiators inferior to annular? Just asking.



That would imply a second question: why are annular radiators better than air-cooled radials? I await a reply with actual data.


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## P-39 Expert (Jul 1, 2019)

Shortround6 said:


> Guys, see : http://www.wwiiaircraftperformance.org/P-39/P-39D_41-6722_PHQ-M-19-1325-A.pdf
> 
> In level flight at over 360mph (plane hit 368mph) the P-39D could hold 1150hp to 13,800ft.
> When climbing at about 190mph it could hold 1150hp to 12,400hp.
> ...


Difference in critical altitude just the difference in ram air speed 368mph vs. 190mph? Would seem right.

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## tomo pauk (Jul 1, 2019)

swampyankee said:


> That would imply a second question: why are annular radiators better than air-cooled radials? I await a reply with actual data.



If by 'better' you mean 'less draggy', the actual data by Focke Wulf noted halving of cooling drag when a state-of-the-art (w.r.t. to streamlining) BMW 801D was replaced by the Jumo 213A engine (has annular radiator). Fuselage drag was also reduced by 10%. FWIW: table (cooling drag is noted as 'Kuehlung' under 'Widerstnadsenteile' - 'Drag breakdown'; fuselage drag is under 'Rumpf +K.A.', along with interfrence drag and ventilation drag).

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## Zipper730 (Jul 4, 2019)

tomo pauk said:


> P-38 as a classic twin, with leading-edge radiators . . . . elongated chord of the wing by 20% as suggested by NACA . . . coolers in the new leading edge


Actually, this is a very good idea. I'm not sure when they first started extending the tail, whether this was before they re-powered the wind-tunnel, but by some point in 1942, they modified a P-38E into the Swordfish model, which had an extended tail-cone for the gondola.

The proposals in early 1942 for the radiators in the leading-edge and a redesigned inboard airfoil, would have almost certainly served to both reduce cooling drag, and maximum dive speeds. I'm curious if they planned to keep the intercoolers in the wing-leading edge.


> plus all of late improvements that P-38L had need to be introduced earlier (from better cockpit heating on)


Agreed


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## GrauGeist (Jul 4, 2019)

The "swordfish" airframe was purely for testing and didn't go anywhere - much like the XP-58.


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## Zipper730 (Jul 4, 2019)

GrauGeist said:


> The "swordfish" airframe was purely for testing and didn't go anywhere - much like the XP-58.


No, I'm aware of that, but it illustrates an interest in reshaping the gondola. Combined with the NACA report, it's surprised they didn't add 20% wing-chord inboard, add the radiators in the leading-edge, and extend the tailcone


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## pbehn (Jul 4, 2019)

swampyankee said:


> That would imply a second question: why are annular radiators better than air-cooled radials? I await a reply with actual data.


I would say wing leading edge radiators were the best set up simply because so many late and post war planes ended up with them.

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## drgondog (Jul 4, 2019)

Zipper730 said:


> No, I'm aware of that, but it illustrates an interest in reshaping the gondola. Combined with the NACA report, it's surprised they didn't add 20% wing-chord inboard, add the radiators in the leading-edge, and extend the tailcone


Major re-design and re-tool - perhaps a year's delay in production that War Production Board would never approve.

20% increase in chord combined with reduced wing span would increase both parasite drag and induced drag - would not improve dive characteristics unless the airfoil was changed - both represent another huge delay in production.

Last but not least, the chin radiator did not have that much drag over the E through H design.

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## Ivan1GFP (Jul 4, 2019)

tomo pauk said:


> ..... Plus, they add more length or tubes, meaning increase of vulnerable area.



Hello Tomo Pauk,
This seems like a pretty minor difference for some potentially great reductions in drag: The Mustang and other aircraft with radiators and oil coolers located very far aft on the fuselage all have longer tubes for oil or coolant but the aft radiator location seems to be the optimal setup. Note that this was done even for the oil cooler on the La-7 which had its oil cooler moved quite a bit further aft than on La-5FN.
The P-38 Lightning also had rather long coolant lines back to its radiators.



drgondog said:


> Last but not least, the chin radiator did not have that much drag over the E through H design.



Hello drgondog,
I can't recall the source, but I have seen a mention that at the same cruise power settings, the earlier aircraft were noticeably faster so there was a significant difference in drag in the new intercooler setup. The maximum speed of the later aircraft was much increased because they were able to run higher sustained maximum power settings because of the increased efficiency of these same improved intercoolers.

- Ivan.


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## drgondog (Jul 4, 2019)

Ivan1GFP said:


> Hello Tomo Pauk,
> This seems like a pretty minor difference for some potentially great reductions in drag: The Mustang and other aircraft with radiators and oil coolers located very far aft on the fuselage all have longer tubes for oil or coolant but the aft radiator location seems to be the optimal setup. Note that this was done even for the oil cooler on the La-7 which had its oil cooler moved quite a bit further aft than on La-5FN.
> The P-38 Lightning also had rather long coolant lines back to its radiators.
> 
> ...


Define "noticeably faster" and separate Induced Drag increases due to more GW? Stick with P-38J-5/-10 comparison because earlier versions couldn't exploit the extra HP yet.


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## Zipper730 (Jul 5, 2019)

drgondog said:


> Major re-design and re-tool - perhaps a year's delay in production that War Production Board would never approve.


That bad?


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## pbehn (Jul 5, 2019)

Zipper730 said:


> That bad?


There were a huge number of plane types that weren't improved when they could have been because it would have resulted in less planes in service. Changes to design especially when un planned and not researched can cause huge losses in production.

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## Zipper730 (Jul 10, 2019)

drgondog


Could the tailcone extension have been fitted? That seems fairly simple, and would have increased performance quite a bit.

As I understand it, the problems with the P-38 involved compressibility, which was effectively caused by...

Airflow reaching and exceeding the speed of sound on the wings and tails, which eventually serves to produce turbulent flow that reduces stabilizer/elevator effectiveness: This was exacerbated by the fact that, predominantly, the gondola caused the airflow to accelerate over it and the wings to a combined sonic/supersonic velocity earlier than each would alone, and; the stabilizer was fairly sensitive to turbulent airflow, as evidenced by the fact that opening the canopy windows could cause buffeting
The filleting to the inboard wings basically smoothed out the junction between gondola and stabilizer and reduced the interference effects between the two surfaces (the description seems almost to sound like area-ruling, whether that was the intention or not): I could also imagine that the blending would reduce turbulent flow not just through the increase of critical mach-number, but also by preventing the two airflows from interacting badly with one another (i.e. less turbulence, particularly over the stabilizer).
The gondola tailcone-extesion as done on the P-38 Swordfish and earlier wind-tunnel proposals in 1942 (far as I remember) seemed to reduce interference effects at the trailing edge of the wing, and would reduce turbulence to structures located behind them.
I remember being told the tail-cone extension improved the diving ability of the P-38 Swordfish (not sure how much also had to do with the outboard wings fitted with laminar flow foils).

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## Zipper730 (Jul 11, 2019)

I was also thinking of something else: The XP-49 was an all new design, and originally built to use the X-1800 engine (H-2240/2600), and ended up using the XI-1430. I'm curious why they'd put the XI-1430 in there? It was less powerful than the X-1800 (XI-1430 = 1600 HP), which produced around 2000 horsepower.

Why not put the H-2470 in there? It was actually a little bit shorter than the X-1800 (91.13 vs 107) and produced more power (2300).


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## wuzak (Jul 11, 2019)

Zipper730 said:


> I was also thinking of something else: The XP-49 was an all new design, and originally built to use the X-1800 engine (H-2240/2600), and ended up using the XI-1430. I'm curious why they'd put the XI-1430 in there? It was less powerful than the X-1800 (XI-1430 = 1600 HP), which produced around 2000 horsepower.
> 
> Why not put the H-2470 in there? It was actually a little bit shorter than the X-1800 (91.13 vs 107) and produced more power (2300).



The H-2470 may not have existed at that time.

The XP-49 was not an all-new design since it used the P-38's wing.


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## wuzak (Jul 11, 2019)

XP-49 prototype was to have XH-2600s installed, but production aircraft were to have the R-2160 Tornado.

"Both the USAAC and Lockheed soon came to realize that with either the Pratt & Whitney XH-2600 or the Wright R-2160 engines, the XP-49 would be seriously overpowered."

"Two-thirds of the XP-49 airframe components were common with the P-38."

Lockheed XP-49


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## Zipper730 (Jul 11, 2019)

wuzak said:


> The H-2470 may not have existed at that time.


I think you might be right, my source (admittedly, Wikipedia, but I think it's still right) seems to say that the H-2470 was conceived when the O-1230 proved uncompetitive in power-output.


> The XP-49 was not an all-new design since it used the P-38's wing.


Proposed in 1939


wuzak said:


> XP-49 prototype was to have XH-2600s installed, but production aircraft were to have the R-2160 Tornado.


What problems affected the Tornado?


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## wuzak (Jul 11, 2019)

Zipper730 said:


> Proposed in 1939



That is correct. It is also before the first YP-38s had been built.


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## pbehn (Jul 11, 2019)

Zipper730 said:


> Could the tailcone extension have been fitted?


Not may post.


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## Zipper730 (Jul 11, 2019)

Okay, here's something a bit older: The Y1P-37. 
The concept was actually not all that out there: A P-36 with a V-1710 and a turbocharger. The method of implementation, however left a lot to be desired.











Looking at the basics of the design...

The wings and landing-gear seem basically the same as the P-36: That's good. They were aerodynamically and structurally sound.
The turbocharger didn't appear to be placed in a bad location: This is good, it takes up little space
Main fuel tanks appear to be in the inboard-wings: This is good. It seems to provide adequate capacity, while simultaneously not taking up excessive space in the plane.
The auxiliary fuel tank is positioned behind the intercooler, and in front of the cockpit: This is bad. While it was based on the P-36, the P-36 had a compact radial engine up front, not a long inline engine; it also did not have any intercoolers (or radiators) to deal with.
Possible remedy: Reposition the auxiliary tank behind the pilot, as was done on the later P-40. While I'm not sure what the USAAC regs were over the years, there is physical room for it.

The intercooler/radiators are positioned behind the engine: This is bad as this adds length behind the engine, and ahead of the nose
I'm not sure if the intercooler is liquid/air or air/air because, while air/air is normal; the two are so close to each other, I can't really tell the exact details.


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## gumbyk (Jul 11, 2019)

Zipper730 said:


> Okay, here's something a bit older: The Y1P-37.
> Looking at the basics of the design...
> 
> The wings and landing-gear seem basically the same as the P-36: That's good. They were aerodynamically and structurally sound.
> ...



Putting the aux fuel tank so far aft will result in a large shift in C of G as fuel is burnt off. It is best if all consumables (fuel, ammunition) are located as close to the centre of gravity as possible.
Increasing intercooler pipe length adds inefficiencies to the system, shortening it means that you have the issues you noted - its a trade-off in design that I'm sure they would have taken into account.


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## Zipper730 (Jul 11, 2019)

gumbyk said:


> Putting the aux fuel tank so far aft will result in a large shift in C of G as fuel is burnt off. It is best if all consumables (fuel, ammunition) are located as close to the centre of gravity as possible.


The P-40 had the auxiliary tank behind the pilot. I'm not sure if it was designed to use this tank in combat or for ferrying. Regardless, it worked okay, from what it appears.


> Increasing intercooler pipe length adds inefficiencies to the system


Well, yeah, but you have to see over the nose too...


S
 Shortround6

W
 wuzak

Is that intercooler liquid/air or air/air? Looking at the diagram, I can't really tell as it's so close to the main radiator.


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## wuzak (Jul 11, 2019)

Zipper730 said:


> The P-40 had the auxiliary tank behind the pilot. I'm not sure if it was designed to use this tank in combat or for ferrying. Regardless, it worked okay, from what it appears.



The pilot is so far back that moving a fuel tank behind the pilot would be bad.




Zipper730 said:


> Is that intercooler liquid/air or air/air? Looking at the diagram, I can't really tell as it's so close to the main radiator.



It is an air-to-air intercooler.


The big improvement to the YP-37 would be changing the position of the coolers. You could put the intercooler ahead of the turbo, under the chin. The radiator would then have to go under the wings or on the leading edge of the wings.


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## Shortround6 (Jul 12, 2019)

Zipper730 said:


> The P-40 had the auxiliary tank behind the pilot. I'm not sure if it was designed to use this tank in combat or for ferrying. Regardless, it worked okay, from what it appears.



The P-36/Hawk 75 had the the auxiliary tank behind the pilot. The radial engine plane was shorter and lighter and the tank was a true ferry tank, combat and acrobatic maneuvers were prohibited with fuel in the tank. The P-40s had no such prohibition but then the fuel tank was being used as a counter balance to the longer heavier engine (this varied somewhat depending on version). 
The regular fuel tanks were were in the wing center section (under the fuselage/cockpit).
Putting fuel tanks some distance from the CG can cause a lot of trouble.

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## Zipper730 (Jul 12, 2019)

wuzak said:


> The pilot is so far back that moving a fuel tank behind the pilot would be bad.


Yes, but if the radiator and intercooler layout were altered, it would allow the cockpit to be more conventionally forward. This would produce a shape similar to the P-40.


> It is an air-to-air intercooler.


Thanks


> The big improvement to the YP-37 would be changing the position of the coolers. You could put the intercooler ahead of the turbo, under the chin.


I assume you mean the intercooler radiator? Sounds silly, but air-to-air intercoolers do have an intake.


> The radiator would then have to go under the wings or on the leading edge of the wings.


That looks like it would be workable.


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## wuzak (Jul 13, 2019)

Zipper730 said:


> I assume you mean the intercooler radiator? Sounds silly, but air-to-air intercoolers do have an intake.



I mean the intercooler. With an air-to-air there is no need for a secondary radiator.

I was thinking along the lines of the intercooler placement on the P-38J/L.


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## Zipper730 (Jul 13, 2019)

wuzak said:


> I mean the intercooler. With an air-to-air there is no need for a secondary radiator.


As I understand it, an intercooler includes air drawn in from the outside, and cycled through tubes/grills/passageways (a radiator) which absorb the heat from the air passing through the carburetor intake on the way to the engine. The heat from the carburetor is transferred to the airflow in the intercooler, which then is routed overboard.

So the intercooler is a radiator, it gets it's coolant from the outside if it's an air/air intercooler.


> I was thinking along the lines of the intercooler placement on the P-38J/L.


Makes sense, but I'm figuring the turbo has hot exhaust gas flowing out of it. If the duct was like the P-38J, wouldn't the air get cooled off, then heated up by a whole bunch of hot exhaust gas blowing in (this might sound stupid, but it's 2 AM so my thinking might not be all that perfect)?

Would it be possible to bifurcate the duct around it without too much increase in frontal area, or mount the turbo on its side?


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## wuzak (Jul 13, 2019)

Zipper730 said:


> As I understand it, an intercooler includes air drawn in from the outside, and cycled through tubes/grills/passageways (a radiator) which absorb the heat from the air passing through the carburetor intake on the way to the engine. The heat from the carburetor is transferred to the airflow in the intercooler, which then is routed overboard.
> 
> So the intercooler is a radiator, it gets it's coolant from the outside if it's an air/air intercooler.



I meant to distinguish between the air-to-air intercooler, which is a single heat exhchanger, with the liquid-to-air intercooler which has two heat exchangers - the intercooler and the radiator.




Zipper730 said:


> Makes sense, but I'm figuring the turbo has hot exhaust gas flowing out of it. If the duct was like the P-38J, wouldn't the air get cooled off, then heated up by a whole bunch of hot exhaust gas blowing in (this might sound stupid, but it's 2 AM so my thinking might not be all that perfect)?
> 
> Would it be possible to bifurcate the duct around it without too much increase in frontal area, or mount the turbo on its side?



You may note that I said the intercooler would be mounted ahead of the turbo.

On the YP-37 the turbo was mounted below the engine, with the turbine section at the bottom.

The compressor sat above that, and would feed forward to the intercooler. It would, most likely, not cross the path of the exhaust system. The outlet would feed back to the carburettor, and with careful design it should be reasonably clear of the exhaust system.

The exhaust from the turbo would dump below the aircraft on the centreline. This would be heading away from the intercooler, but precludes the use of a belly scoop radiatior like that in the P-51 (or XP-40). Thus the radiator would have to be positioned elsewhere - the wings, perhaps.

Having the radiator and intercooler and oil coolers under the nose would be impractical. It could be made to work with a liquid-to-air system, with the intercooler mounted at the back of the engine and the intercooler radiator mounted with the engine coolant radiator.


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## Zipper730 (Jul 13, 2019)

Deleted: I hate it when I think of something, then forgot it...


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## wuzak (Jul 13, 2019)

Zipper730 said:


> So it would just go around the pathway of the turbine outlet? Forcing air forward like that sounds like an awesome way to produce drag.



The turbine outlet is facing down form the aircraft. The intercooler pipes are inside the aircraft.


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## Zipper730 (Jul 13, 2019)

wuzak said:


> The turbine outlet is facing down form the aircraft.


That I'm aware of, but I'm looking at the diameter of the exhaust outlet where the airflow goes through the turbine and out...






... as I understand it, it's that ring shaped hole with the blades: I'm thinking that, thing's gotta be something like 1.5-3.0 feet in diameter.

Looking at the airflow path on the XP/YP-37: The carburetor intake goes slightly upwards; then rearwards to pass through the compressor. From that point, it goes through the intercooler, and from there, upwards, and then forwards to the fuel injection manifold and main-stage supercharger, and into the engine? I just want to make sure I'm perceiving everything right


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## BiffF15 (Jul 13, 2019)

Zipper730 said:


> That I'm aware of, but I'm looking at the diameter of the exhaust outlet where the airflow goes through the turbine and out...
> 
> View attachment 544586
> 
> ...



Zipper,

Nice shot!

Greg,

Any idea how many Lightning’s are flying with operational turbos?

Cheers,
Biff


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## wuzak (Jul 13, 2019)

Zipper730 said:


> Looking at the airflow path on the XP/YP-37: The carburetor intake goes slightly upwards; then rearwards to pass through the compressor. From that point, it goes through the intercooler, and from there, upwards, and then forwards to the fuel injection manifold and main-stage supercharger, and into the engine? I just want to make sure I'm perceiving everything right



I guess it has to, since enter under the nose and go into the compressor inlet.

In the case of the YP-37 the inlet is on top of the installed turbo. The XP-37 used a different turbo design, at least initially, where the air entered the compressor in the space between the compressor and turbine housings.

The P-40F had the radiator mounted under the nose and an updraft carburetor, so the arrangement I propose is possible.


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## wuzak (Jul 13, 2019)

Zipper730 said:


> As I understand it, an intercooler includes air drawn in from the outside, and cycled through tubes/grills/passageways (a radiator) which absorb the heat from the air passing through the carburetor intake on the way to the engine. The heat from the carburetor is transferred to the airflow in the intercooler, which then is routed overboard.



The intercooler on a V-1710 plus turbo is before the carburetor. I think you mean compressor.




Zipper730 said:


> Makes sense, but I'm figuring the turbo has hot exhaust gas flowing out of it. If the duct was like the P-38J, wouldn't the air get cooled off, then heated up by a whole bunch of hot exhaust gas blowing in



The air that is cooled is inside the ducting that is routed back to the engine.

The exhaust does not enter the ducting. The only way the exhaust affects the cooled air is if the manifolds or exhaust gas passes close by the duct, transferring heat.

The exhaust gas from the turbo in my hypothetical P-37 would enter the air that has been warmed by the intercooler.


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## pinsog (Jul 14, 2019)

Zipper730 said:


> That I'm aware of, but I'm looking at the diameter of the exhaust outlet where the airflow goes through the turbine and out...
> 
> View attachment 544586
> 
> ... as I understand it, it's that ring shaped hole with the blades: I'm thinking that, thing's gotta be something like 1.5-3.0 feet in diameter.



Here are the sizes for early turbochargers on P38. Not sure what model P38 your pic is

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## Zipper730 (Jul 14, 2019)

wuzak said:


> You may note that I said the intercooler would be mounted ahead of the turbo.


That's one idea, but I was also thinking about the fact that, with the radiator repositioned to the wings; the volume of the intercooler could be reduced and shaped in a way to be more compact. Furthermore, the size of the nose would probably allow an oil-cooler to be there even if the radiator wouldn't fit in the nose.

As for the intake path for the intercooler, would there be enough room in the wings to pull that off, or would you cut into the wing-fuel space?

Well, that aside, I'd also thought about removing and repositioning equipment, much as was done in the P-40.

Auxiliary Fuel Tank: Repositioned behind/below pilot
Radio-Transmitter & Receiver: Repositioned aft of cockpit
Battery: Repositioned aft of cockpit
Hydraulic Tank & Pump: Repositioned aft of cockpit
Just with those mods alone, about this much length could be trimmed off the nose.


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## Shortround6 (Jul 15, 2019)

The stuff may fit behind the cockpit (although you are working on a 2 dimensional plan) see;




fuselage is lot narrower behind the cockpit,
Tail has to say a certain distance behind the wing or control of the aircraft goes out the window (plane becomes unstable)
Just because something "fits" doesn't mean the weight and balance are going to be correct, stuffing a lot of heavy stuff in the rear of the plane leads to sme real CG problems,

The YP-37 may look long, but it was actually 9 inches shorter than P-40, P-40B & C


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## tyrodtom (Jul 15, 2019)

The XP-37 has basically nothing behind the cockpit except that baggage compartment, ( which if you look at the specs, is probably limited to 20-30 lbs)

Moving equipment back there whose combined weight is probably at least a couple hundred pounds just wouldn't work out CG wise.


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## Zipper730 (Jul 15, 2019)

Shortround6 said:


> The stuff may fit behind the cockpit (although you are working on a 2 dimensional plan)


I really do appreciate the three-view image. It reveals some stuff of great use

I didn't realize the design had such large fillets: The P-36 didn't seem to have them, and neither did the P-40 for that matter, actually.
The carburetor intake is interesting to say the least. I didn't know the intake was only on one side.
It does raise some questions about where some things could be repositioned: For starters, I'm curious if the radiator space also includes the oil-cooler (the radiator, intercoolers are all next to each other). Also how big is the oil-cooler relative to the carburetor intake?


> fuselage is lot narrower behind the cockpit . . . . The YP-37 may look long, but it was actually 9 inches shorter than P-40, P-40B & C


The P-40 is actually fairly narrow in the back. This design is a bit plumper up-front, which I'm not sure is due to the turbocharger (most likely due to the displacement of various other items), the radiator configuration, or the fact that the exhaust pipes have to be tapped to feed the turbocharger.

I'm not entirely sure how the C/G compares to the P-40, as it's a little bit shorter, but the wings do look a bit further back on the airframe. I'm surprised that the design would have less weight up front than the P-40 (the turbocharger and everything): The only thing that would likely result in more weight in the middle/aft would be the radiator position (on the P-40 it's below the nose), though the XP-40 actually had a belly radiator proposed (it didn't seem to work).

How much mass is in the cockpit?


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## pinsog (Jul 15, 2019)

If you want to turbocharge the P40 I think your going about it the wrong way by using the YP37 as a starting point. If you want to turbo charge the P40, I think the best way would be to start with a standard P40, put the turbocharger behind the cockpit partially exposed like a P43. Make just enough space down the middle of the plane between the wing tanks for a 6 inch diameter pipe half exposed in the belly going to the turbocharger and the return pipe on top of that one. I have no idea where the intercooler would go, I guess in the back near the turbocharger with flaps to control the amount of air. 

Personally I think the P36/Hawk 75 would be MUCH easier to turbocharge. Intercooler directly behind engine with turbocharger just like P43, in the belly behind cockpit, exposed, pipe to turbocharger half exposed, return pipe on top. Turbocharged P36/Hawk 75 would be much slower than P40, especially at low altitude, but would climb like crazy compared to any contemporary fighters with no drop in performance at high altitude. I believe this plane could have dominated early war up through 1941 in Europe and done well in the pacific through 1944. Using the cube rule, a P36/Hawk 75 with a turbo charger should do around 360 at 25,000 feet.

While we are at it, put it in a wind tunnel and clean up that wing and landing gear, you don’t see those bulges and crap on a Zero, one of the keys to a Zero’s performance on such low power.

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## MX-2054 (Jul 25, 2019)

Shortround6 said:


> Now, does that mean guns that didn't exist (but could be made with existing technology?)
> Engines that wouldn't exist for a year or more?
> 
> and so on.


At that point it just becomes the "ideaI piston-engine WWII fighter design*," which I have a very detailed idea of by now, but I'm sure everyone has their own idea of one too. For that I just used the GSh-30-1. It makes the armament design much easier but certainly isn't a WWII design even if it can be made with WWII technology.

*More accurately described as the fighter (including engine, weapons, etc.) you would create if you had to design/specify one from scratch in the 1930's.


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## Shortround6 (Jul 25, 2019)

MX-2054 said:


> For that I just used the GSh-30-1. It makes the armament design much easier but certainly isn't a WWII design even if it can be made with WWII technology.




Can it be made with WW II technology (or pre-war technology)?

There may be nothing about the design that is really startling. But the devil is always in the details. There were a lot of improvements in metal alloys and heat treatment between WW II and the 1980s that allowed for higher performing guns at low weights. Assisted by better testing techniques and quality control. 
The lowering of the life span of the guns (making them semi disposable) didn't hurt the weight either 

The GSh-30-1 needs a pretty good engine too. While the gun is light the ammo is not. 100 rounds weighs almost twice what the gun does and that 100 rounds weighs as much as 600 round of .50 cal ammo or 3000 rounds of .303/7.7mm. 
The 30mm is much more destructive but you either need to fire one gun through the prop hub (which may be all you need?) or you need a large engine in order to haul one gun in each wing with ammo.


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## P-39 Expert (Jul 25, 2019)

Definitely all you would need.


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## Zipper730 (Jul 25, 2019)

pinsog said:


> If you want to turbocharge the P40 I think your going about it the wrong way by using the YP37 as a starting point. If you want to turbo charge the P40, I think the best way would be to start with a standard P40


I agree with this idea. 

Does anybody have a drawing of the P-40J proposal, which was to involve a turbocharger. Nothing was ever built, but I'm curious if any drawings exist.


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## Kevin J (Jul 25, 2019)

Zipper730 said:


> I agree with this idea.
> 
> Does anybody have a drawing of the P-40J proposal, which was to involve a turbocharger. Nothing was ever built, but I'm curious if any drawings exist.



It's called a P-60. P-40 fuselage with larger laminar flow wing.


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## Zipper730 (Jul 25, 2019)

Kevin J said:


> It's called a P-60. P-40 fuselage with larger laminar flow wing.


I thought that came later?

Regardless, where did they put the turbo?


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## MX-2054 (Jul 25, 2019)

Shortround6 said:


> Can it be made with WW II technology (or pre-war technology)?
> 
> There may be nothing about the design that is really startling. But the devil is always in the details. There were a lot of improvements in metal alloys and heat treatment between WW II and the 1980s that allowed for higher performing guns at low weights. Assisted by better testing techniques and quality control.
> The lowering of the life span of the guns (making them semi disposable) didn't hurt the weight either


It should be able to be built with WWII or earlier technology, with some increased weight and reduced barrel life. Metallurgy has relatively little to do with improved gun performance, it mostly increases barrel life and allows the gun to be made slightly lighter by making its component parts lighter. The smaller size and improved performance of guns (rate of fire for a given cartridge) is mostly due to mechanical improvements. The mechanical design of the GSh-30-1 in particular is very efficient, with its lever-based system allowing it to mostly keep its rate of fire even when redesigned with a heavier barrel.

I'd guess a WWII GSh-30-1 would be about 60-65 kg, and have a barrel that would essentially have to be replaced after firing a single load of ammunition, but would still have the same rate of fire and size. It would be mounted in the propeller hub (it can't be synchronized and if it was wing-mounted outside the propeller arc its recoil alone would necessitate a very heavy and strong wing).



Shortround6 said:


> The GSh-30-1 needs a pretty good engine too. While the gun is light the ammo is not. 100 rounds weighs almost twice what the gun does and that 100 rounds weighs as much as 600 round of .50 cal ammo or 3000 rounds of .303/7.7mm.
> The 30mm is much more destructive but you either need to fire one gun through the prop hub (which may be all you need?) or you need a large engine in order to haul one gun in each wing with ammo.


For that I required an electronic rate reducer (used on the A-12.7) to allow the gun to be fired at full or half its rate of fire. 10 seconds of cannon fire (the lowest commonly found time in WWII fighters) would require 250 rounds at 1500 rpm, and 125 at 750 rpm. The 250 rounds would be too heavy, so I settled for 150 rounds (coincidentally the same as the ammunition load of the gun in real life), and assumed the gun would have to be fired at reduced rate to get 10 seconds of fire out of it, with the full rate used in situations requiring more firepower.


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## wuzak (Jul 25, 2019)

Zipper730 said:


> I thought that came later?
> 
> Regardless, where did they put the turbo?




I believe it was under the nose or under the centre wing area. Hard to tell.





File:XP-60 - Ray Wagner Collection Image (27409064984).jpg - Wikimedia Commons 

The XP-60 program started as the XP-53 program with the IV-1430. The XP-60 flew a couple of months after the first P-40/Merlin did.


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## Shortround6 (Jul 25, 2019)

MX-2054 said:


> The smaller size and improved performance of guns (rate of fire for a given cartridge) is mostly due to mechanical improvements.


And better springs.


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## Zipper730 (Jul 27, 2019)

*Regarding the "Shortnose P-37"*



wuzak said:


> I believe it was under the nose or under the centre wing area. Hard to tell.


Understood. I'm curious if any other members, such as 

 drgondog

P
 pinsog

S
 Shortround6


 tomo pauk

T
 tyrodtom
would have anything of use...

Until I get anymore information on that, I was thinking about some other ideas.


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## pinsog (Jul 27, 2019)

I had thought of taking a P36 and moving the engine forward just a bit if needed, removing the cowl guns and putting a turbocharger behind the engine. But I keep thinking about how those engines sling and leak a lot of oil and the problems a hot turbocharger right behind that might cause. Be a nice tight power pack if it could be done.

Any thoughts on that setup?


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## wuzak (Jul 27, 2019)

The regular intake didn't suffer from ingesting oil, so that wouldn't be a problem.

As far as oil hitting the turbo, I'm guessing it would be a very small amount and probably in a very fine mist. If it was going to be a problem you could put a guard around the turbo to prevent the oil getting on the hot bits.


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## John Frazer (Jul 27, 2019)

As s panacea, to make any of them better, or replace them with something different in only one thing, replace some/most of the fuselage with lifting body.
Instant increase in range/ speed &/or payload.

Simplest from the Eshelman patents, is practically a very large fillet. Shrink the non-lifting fuselage down to a pod for pilot & engine, and a boom projecting the tail aft.
Increase the center span to huge chord & camber, housing everything not in the wings.
More marked is the Burnelli, which can be extended into a huge bomber or transport, or maritime/ASW plane.

Some have made the mistake of calling Burnelli type things a sort of all-wing or the media term flying wing. Nope. Simply eliminating or replacing non-lifting drag.
Anything from a fighter to a transport benefits, and there's no doubts about controllability or instability as with a tail-less fin-less all-wing.


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## John Frazer (Jul 27, 2019)

Higgins-Bellanca 39-60
Transport, 1944

Clare K. Vance, 1930s 7500NM range

Arado maritime / bomber E-470
"F" model with jets, "America bomber

Antonov LEM-2

De Monge, before going to work for Bugati on their "blue" racer, worked on the stupendously ugly planes built by Dyle Et Bacalan

Northrop Avion1 "216"

All show that the ideas were known.
Only lack of support stopped them. (and in some cases, the start of the war, in others, the end of it)

Design mechanics of any particular iteration might have troubled some, but the design concept was sound.
The Kalinin giant 8-engine K-7 comes to mind.


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## Zipper730 (Jul 28, 2019)

*Davis Manta*

It was a long-ranged fighter proposed by David R. Davis revolving around the fluid-foil he designed, but with a manta-ray planform with an aspect ratio in the range of 6.0-6.5. Two configurations were proposed, one of which was a tractor-prop design and a single fuselage; the other was a twin-boomed design with a contra-rotating pusher-prop. Both had a nose-gear, a raised-up cockpit/canopy, provision for four 20mm cannons and four 0.50" machine guns in the wings. It appeared to be powered by an Allison V-1710 with turbocharging.

While the aircraft was fairly large, at 26" longer than the P-38, though it's wingspan was 24" less, the empty weight might have been less than expected owing to the aircraft having a blended wing/fuselage configuration which can produce greater strength to weight, though I never saw a weight figure published for the aircraft design.

These are some pictures that were published...











While there were clearly some problems with the design, such as the fact that the V-1710 would almost certainly never have delivered the 430-440 mph requirements specified, something only further confirmed by the fact that the wind-tunnel model supposedly "disappeared" when Davis fell under investigation: Much of it could potentially have been fixed with more powerful engines, of which the H-2470 and V-3420 appeared able to deliver the desired performance, taller landing-gears, and bigger propellers.

An artist named Justo Miranda had done an artist-conception of this design powered by an V-3420 (possibly under the misconception that the aircraft was to be powered by the V-3420 instead of the V-1710), which depict both proposals.







The following members might have some insights I don't have



 drgondog
, 
P
 pinsog
, 
S
 Shortround6
, 
W
 wuzak
, 
X
 XBe02Drvr


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## Zipper730 (Jul 28, 2019)

Another design that I had some interest in would be the XP-54: Of all the R-40C designs, it had the most potential in terms of being a workable design. It had a method for cockpit egress and avoiding getting turned into ground-meat from the propellers.

It seems the problem was that it got too heavy, and I'm curious why.


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## John Frazer (Jul 28, 2019)

Then there are the more nearly all-wing (with fin/rudder, but without tail or separate stab/elevator. (Google translates a German site as calling such a thing "brush-less")
Still frequently called by the media term "flying wing" but disdained by all-wing purists because they had rudders.
Note that to this day, not a single all-wing sort without that fin/rudder &tractor prop have failed to make a workable plane that wasn't highly risky experimental, "not ready for consumers". This goes for the Hortens, despite a few sport gliders of their sort, Northrop, the B-2, the present-day Horten HX-2.

Most designers of such things wanted to make big planes, with everything inside, but with tiny test planes, they had a "fuselage-ish" pod for the engine in front and the pilot. All tried tail-less and failed, as with wing-tip fins. All but the Hortens and Northrop settled on tractor prop with the fin/rudder right aft in the prop- blast, and made functional utility planes.

Cheranovsky succeeded with the BICh--3 & 7a, Fauvel similarly with the AP-10 and later AV-36 sport gliders (several up to the present day flying, the little "Pelican" a derivative). The Arups were apparently entirely brilliant successes, and Canova made a good aerobatic glider before losing support to make a plane. Payen for Aubrun built one like the Arup/Hoffman with very low aspect ratio before moving on from something the "markets" studiously ignored.
Moskalyev made a successful little test plane with even more of a distinct fuselage half in the wing, ignored.
All these were well before the war, some stopped by it. The Eshelman "Spirit of National Defense" ("flounder") and the Lippisch dfs-39c (tractor & fin/rudder, discarding the little "canards") succeeded during the war.
Most seem to have had remarkable speed on little power, efficiency being the promise of all-wing.
Short aspect-ratio planes had their trick of using "parachute lift" to fly slowly while still being sleek & quick, the Arup/Hoffman sorts being stall/spin-proof while being nimble & quick.


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## wuzak (Jul 28, 2019)

Zipper730 said:


> Another design that I had some interest in would be the XP-54: Of all the R-40C designs, it had the most potential in terms of being a workable design. It had a method for cockpit egress and avoiding getting turned into ground-meat from the propellers.
> 
> It seems the problem was that it got too heavy, and I'm curious why.



It got big!



wuzak said:


> An indication of how big the XP-54 was is that the centre fuselage was longer than the Spitfire, P-51, P-47, Tempest V, Fw 190D-9, Ta 152H and is only a few inches shorter than the P-38.
> 
> It's overall length was longer than the P-61, A-26 and Mosquito and only slightly shorter than a B-26 Marauder.



Part of the problem was the pressure cabin, which dictated the egress system. 

Then there was using two 37mm M4 cannon and two 0.50" HMGs, and then needing a compensating mechanism so that the cannon and machine guns hit the same target. The original scheme was for all 0.50" HMGs or a combination with 20mm cannons.

The design was originally to have the XH-2600 (X-1800), then went to the XH-2470. It was planned to use the XR-2160 Tornado when that became available, so the structure to support that engine, which was heavier and more powerful, but also a completely different shape to the other engines. So the engine support structure was probably heavier than it would have otherwise needed to be.


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## Zipper730 (Jul 28, 2019)

wuzak said:


> It got big!


What factors drove up the aircraft's overall size?


> Part of the problem was the pressure cabin, which dictated the egress system.


Why was the pressurization system a requirement? The P-51 and P-47's both flew at similar altitudes and didn't require it.


> Then there was using two 37mm M4 cannon and two 0.50" HMGs, and then needing a compensating mechanism so that the cannon and machine guns hit the same target. The original scheme was for all 0.50" HMGs or a combination with 20mm cannons.


I thought the traversable guns was just something Vultee adopted on their own initiative...


> The design was originally to have the XH-2600 (X-1800), then went to the XH-2470. It was planned to use the XR-2160 Tornado when that became available, so the structure to support that engine, which was heavier and more powerful


The H-2600 and H-2470 both weighed 2400 pounds, with the R-2160 weighing 2350. Power output varied by about 50 horsepower maximum. The reconfiguration of the engine mounts might have played a role.

Was there any change in altitude requirements from the earliest proposals of the XP-54 to the flying models? Also, what did the XP-68 proposal look like?


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## wuzak (Jul 29, 2019)

Zipper730 said:


> What factors drove up the aircraft's overall size?



The requirements put on it by the USAAF.




Zipper730 said:


> Why was the pressurization system a requirement? The P-51 and P-47's both flew at similar altitudes and didn't require it.



Because the Army wanted it.

I don't know if the P-51 and P-47 could fly at high altitude for prolonged periods without detrimental affects for the pilot.




Zipper730 said:


> I thought the traversable guns was just something Vultee adopted on their own initiative...



The Army specified the armament and Vultee came up with a system to make it work.

The problem with mixing the M4 cannon with the 0.50" HMG was the difference in the trajectory. That is why the nose was built to elevate +3° to -6°. I believe the 0.50" HMGs were fixed and the M4 would be elevated to match the 0.50"s.

They had to come up with a computing gun sight to make it work.




Zipper730 said:


> The H-2600 and H-2470 both weighed 2400 pounds, with the R-2160 weighing 2350. Power output varied by about 50 horsepower maximum. The reconfiguration of the engine mounts might have played a role.



The R-2160 may have been about the same weight, but it definitely was (expected to be) more powerful. As much as 500hp more than the X-1800, and 200-300hp more 



Zipper730 said:


> Was there any change in altitude requirements from the earliest proposals of the XP-54 to the flying models?



Yes, as well as many other operational requirements.




Zipper730 said:


> Also, what did the XP-68 proposal look like?



The XP-68 was the designation for the Tornado powered XP-54.


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## John Frazer (Jul 29, 2019)

USAAC Test Results Sept 1939
Burnelli fighter / bomber X-BAB-3

From studies of the research made by the Burnelli Co., the NACA and the Air Corps, the Military adaptability of the basic design has the following advantages over the orthodox streamlined dead-weight fuselage.

The coefficient of drag is the lowest known for any useful airplane today.
The coefficient of lift is greater .
The lifting fuselage has distinct advantages for the installation of power plants, bombs, armament and all other accessories over the streamlined fuselage.
From wind tunnel tests already conducted by the NACA and NYU the performance is exceptionally good in every phase.
The design embodied extremely good factors of safety -- considerably higher than the streamlined fuselage type.
The design is simple of construction and in the opinion of the Air Corps lends itself to high speed production better than any design and therefore the valuable time element involved in all production contracts can be taken advantage of to its fullest extent.
It is apparently a cheaper airplane to build because of the time element referred to in 6 above.

- - - - - - - - - - - - - -
This was submitted for what was to become the A-20.

Another, possibly related to the A-1 in the other color picture, above.


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## Zipper730 (Jul 29, 2019)

wuzak said:


> The requirements put on it by the USAAF.


I'm just surprised that the early design they were working on used an Allison V-1710 without a turbo. I figure they'd have wanted to get that turbo on the design with a vengeance, or adopt a twin-stage set-up, if they wanted high-speed performance (the best place to get it would be at altitude). After all, the P-40 only ended up with a single-stage supercharger because the turbocharged designs (XP-37/Y1P-37) didn't have enough visibility over the nose.


> Because the Army wanted it.


Supposedly the design went from around 11000 pounds with a wing area in the 200-300 square foot range to 456 square feet, and weight went up to around 15000-19000 pounds when it was loaded.


> I don't know if the P-51 and P-47 could fly at high altitude for prolonged periods without detrimental affects for the pilot.


Never heard anything to say it couldn't: The P-47 routinely operated in the 25000-30000 foot range and if you had no oxygen, you'd be dead in a matter of seconds or minutes. B-17 crews operated around 25000 feet a lot and they flew missions that were several hours in length. If anybody would have had detrimental effects, they would have been more likely.


> The Army specified the armament and Vultee came up with a system to make it work


So they came up with this on their own initiative


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## Zipper730 (Jul 29, 2019)

Why'd the US Navy cancel the H-2470? Also, I'm curious if the USAAF could have taken over the funding if the USN cancelled it


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## XBe02Drvr (Jul 29, 2019)

Zipper730 said:


> Why'd the US Navy cancel the H-2470? Also, I'm curious if the USAAF could have taken over the funding if the USN cancelled it


Jets were on the horizon.

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## XBe02Drvr (Jul 29, 2019)

wuzak said:


> I don't know if the P-51 and P-47 could fly at high altitude for prolonged periods without detrimental affects for the pilot


Anybody who's had a chamber ride can tell you. Above FL 350-360 breathing 100% O2 with an ambient pressure regulator doesn't supply enough partial pressure of oxygen in the blood to stave off hypoxia, so pressure breathing becomes necessary, a very taxing and exhausting exercise. Above approx 450, ambient pressure is not enough to keep the nitrogen in the blood in solution, and it literally "boils" out, resulting in instant death by eruption. If you're going to operate in that altitude range or higher, you need pressurization or a pressure suit, or both.
I've flown a couple hundred hours at FL 250 in a non pressurized turbo 210 Cessna, breathing through nose bags, and let me tell you, though it doesn't feel hard at the time, by the end of the day, you feel like you've been run over by a train.
I can tell you that at 260, I was good for 45 seconds after the mask came off, before the chamber floor came up and kissed my face. And at 370, pressure breathing, I was first in a chamber full of tactical jet aviators to signal "uncle" and have the chamber brought down, after about five minutes. The jet jocks were a little disgruntled that I broke up their little "macho quotient" contest early on.
Cheers,
Wes

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## Shortround6 (Jul 29, 2019)

It was assumed by many in the planning departments/purchasing that the altitudes at which combat took place would keep going up. Which is why the Americans, British, Germans and others had designs/schemes for planes with pressurized cockpits all in the works in 1941-42. However, for a variety of reasons this did not happen with piston engines. At least not to the extent the planners thought.

There is a difference between what the human body will tolerate for 1 to 2 hours and what it will tolerate for 6-10 hours. You could strip down a Spitfire and send the pilot after a JU-86 at over 40,000 ft on occasion. You could not hang a bunch of drop tanks on a Spitfire and fly it to Berlin and back at 40,000ft and expect the pilots (or a large percentage of them) to stay healthy. Or to even stay combat effective. 

Problems with guns, radios, instruments and even ignition systems on the engines kept the combat ceiling lower than expected in addition to the problems of keeping the pilots/crew healthy (or conscious) without pressure cabins. 

Germans had pressure cabins in some early 109Gs, A number of the Bomber "B" designs had pressure cabins (at least to begin with) for example. 

Americans had several designs for bombers with pressure cabins in addition to the B-29 and there were a number of fighter prototypes with pressure cabins. 

But some of the problems took too long to solve and the war was fought (mostly) with unpressurized aircraft.


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## Zipper730 (Jul 29, 2019)

Shortround6 said:


> It was assumed by many in the planning departments/purchasing that the altitudes at which combat took place would keep going up. Which is why the Americans, British, Germans and others had designs/schemes for planes with pressurized cockpits all in the works in 1941-42. However, for a variety of reasons this did not happen with piston engines. At least not to the extent the planners thought.


What reasons? I just thought the issue had to do with specialized high altitude fighters.

I'm not sure what the projected service ceiling, critical altitude, and combat altitude the XP-54 was expected to fly at, but in practice they had a critical altitude of around 28,500 feet. This isn't much different than the P-51. The P-51's seemed to be able to routinely operate at 31000 feet during combat operations over Europe. I'm not sure how high they flew for B-29 escort.


> Problems with guns, radios, instruments and even ignition systems on the engines kept the combat ceiling lower than expected in addition to...


The problems I can see with the guns are temperature related, as for the radios and instruments, I'm surprised altitude would have much effect. As for engine ignition systems, why would that cause a problem?


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## Shortround6 (Jul 29, 2019)

The guns were temperature related. You needed more heat to the guns to keep them operating.

Thin air is less of an insulator than thick air and both radios (which sometimes had 600 volts or more DC running through part of them) and engine ignition systems (thousand of volts) suffered from short circuits and engine cross fired, spark intended for one plug/cylinder jumped to another contact or wire and fired the plug in another cylinder at the wrong time. This caused rough running and loss of power. 
This was solved on some engines by pressurizing the magnetos, some engines required special ignition harnesses. The problems were solved but it took time.


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## swampyankee (Jul 29, 2019)

XBe02Drvr said:


> Jets were on the horizon.




R-2800 was already there, and the navy didn't want to deal with another liquid.


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## tyrodtom (Jul 29, 2019)

Zipper730 said:


> What reasons? I just thought the issue had to do with specialized high altitude fighters.
> 
> I'm not sure what the projected service ceiling, critical altitude, and combat altitude the XP-54 was expected to fly at, but in practice they had a critical altitude of around 28,500 feet. This isn't much different than the P-51. The P-51's seemed to be able to routinely operate at 31000 feet during combat operations over Europe. I'm not sure how high they flew for B-29 escort.
> The problems I can see with the guns are temperature related, as for the radios and instruments, I'm surprised altitude would have much effect. As for engine ignition systems, why would that cause a problem?



One group, squadron, flight, or whatever, of fighters didn't escort the bombers the entire distance, they did it in relays. 
Each fighter group would have only been at that high altitude for the part of the mission that were doing the actual escorting, not before the rendezvous with the bombers, and not after they'd turned over the escort duties to another group.


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## XBe02Drvr (Jul 29, 2019)

tyrodtom said:


> Each fighter group would have only been at that high altitude for the part of the mission that were doing the actual escorting


Like I said earlier, flying unpressurized at 25K breathing O2 for hours on end is really exhausting and doesn't do good things for your mental acuity. Try KMSP to KMPV nonstop in a plane that only trues out at +/- 200 knots. That's why unpressurized civil aircraft are restricted to FL250 and below, regardless of how much O2 they carry.
Cheers,
Wes


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## Zipper730 (Jul 29, 2019)

Shortround6 said:


> The guns were temperature related. You needed more heat to the guns to keep them operating. . . .Thin air is less of an insulator than thick air and both radios (which sometimes had 600 volts or more DC running through part of them) and engine ignition systems (thousand of volts) suffered from short circuits and engine cross fired, spark intended for one plug/cylinder jumped to another contact or wire and fired the plug in another cylinder at the wrong time. This caused rough running and loss of power.


I didn't actually think of that, but it does make sense, the current can jump easier if the air acts as an insulator.


> This was solved on some engines by pressurizing the magnetos, some engines required special ignition harnesses. The problems were solved but it took time.


When did these efforts begin if I may ask?



tyrodtom said:


> One group, squadron, flight, or whatever, of fighters didn't escort the bombers the entire distance, they did it in relays.


Even from Iwo Jima to Japan? In that case they seem to have gone all the way.



swampyankee said:


> R-2800 was already there, and the navy didn't want to deal with another liquid.


Still, couldn't the USAAF have taken over funding? Why didn't the USAAF co-sponsor it early on?


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## wuzak (Jul 30, 2019)

Zipper730 said:


> Still, couldn't the USAAF have taken over funding? Why didn't the USAAF co-sponsor it early on?



It is a question of when the H-2470 would have been available in quantity, and would it be better than an R-2800 or V-3420.

So weighing the investment in the H-2470 against spending the money increasing production of existing programs, such as the V-1710, V-1650 or R-2800.

And then you need to fund aircraft designed around it. The XP-54 clearly wasn't going to be it, and there wasn't much, if anything, else.

The XP-54 was a USAAF project that used the H-2470, so there was some support for the engine.

FWIW, the XP-54 first flew in January 1943 and the engine it used was still an experimental version.


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## GrauGeist (Jul 30, 2019)

Just for the record, the Germans were working on pressurized cabins prior to the war and Heinkel had submitted a high-speed bomber design to the RLM in 1940 that incorporated a pressurized cockpit. It was rejected, however, but that concept eventually became the He219 - which did have a pressurized cockpit as well as ejection seats.


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## swampyankee (Jul 30, 2019)

GrauGeist said:


> Just for the record, the Germans were working on pressurized cabins prior to the war and Heinkel had submitted a high-speed bomber design to the RLM in 1940 that incorporated a pressurized cockpit. It was rejected, however, but that concept eventually became the He219 - which did have a pressurized cockpit as well as ejection seats.



Just for reference, Germany wasn't unique in this regard: the first flight of the pressurized Boeing 307 was in 1938 (Boeing 307 Stratoliner). _Everybody_ was working on pressurization: the US, the UK, the French, etc.


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## P-39 Expert (Jul 30, 2019)

Just asking, but what would be the effect on a Mustang pilot on a five hour mission escorting bombers to Berlin at 25000' with oxygen but no pressurized cabin? Normal Mustang escort mission.


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## XBe02Drvr (Jul 30, 2019)

P-39 Expert said:


> Just asking, but what would be the effect on a Mustang pilot on a five hour mission escorting bombers to Berlin at 25000' with oxygen but no pressurized cabin? Normal Mustang escort mission.


I found 5-6 hours at FL250 in the Cessna 210 left me feeling pretty wrung out. And that was with the autopilot doing most of the work. I'm sure flying formation in a stick and rudder airplane, searching overhead for bandits, and weaving to stay with the bombers would have me dreaming wistfully of my rack back in the UK. And it feels SO good to take that mask off when you get down to 10K!
OTOH, the average 8th AF Mustang pilot was a decade younger and most likely more physically fit than I was at the time of my FL adventures.
Cheers
Wes

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## pinsog (Jul 30, 2019)

XBe02Drvr said:


> I found 5-6 hours at FL250 in the Cessna 210 left me feeling pretty wrung out. And that was with the autopilot doing most of the work. I'm sure flying formation in a stick and rudder airplane, searching overhead for bandits, and weaving to stay with the bombers would have me dreaming wistfully of my rack back in the UK. And it feels SO good to take that mask off when you get down to 10K!
> OTOH, the average 8th AF Mustang pilot was a decade younger and most likely more physically fit than I was at the time of my FL adventures.
> Cheers
> Wes


Love the real world perspective some of you guys bring.

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## Zipper730 (Jul 30, 2019)

wuzak said:


> It is a question of when the H-2470 would have been available in quantity, and would it be better than an R-2800 or V-3420.


Well that would be like saying the V-1710 don't need to be built because the R-1820 and R-1820 were built. There was clearly an interest in the USAAF in inlines.

That said, the V-3420 was awesome in power output but it was quite wide and difficult to mount in fighter-aircraft.


> And then you need to fund aircraft designed around it. The XP-54 clearly wasn't going to be it, and there wasn't much, if anything, else.


And they didn't have a snowball's chance in hell. It wasn't any faster than current aircraft, if anything, it seemed a step backwards.

That said, it seemed better than the XP-55 and XP-56 in terms of stability: From what I remember those designs both had their share of trouble (at least they were lighter though, and the XP-56 did manage to creatively cool a radial and mount it amidships -- hey, let's look on the bright side); regardless, was there requirements for pressurization on the XP-55 and XP-56?


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## wuzak (Jul 30, 2019)

Zipper730 said:


> Well that would be like saying the V-1710 don't need to be built because the R-1820 and R-1820 were built. There was clearly an interest in the USAAF in inlines.



But the V-1710 was in production and in useful aircraft during the war. The H-2470 wasn't.

The V-1710 program predated the existence of the R-1820 and R-1830. The theory of the early 1930s was that air-cooled engines were unsuitable for turbocharging, particularly at high altitudes, where the USAAC wanted their bombers to fly.




Zipper730 said:


> That said, the V-3420 was awesome in power output but it was quite wide and difficult to mount in fighter-aircraft.



It was about 4-5" wider than an R-3350, 6 or 7" wider than an R-2800.




Zipper730 said:


> And they didn't have a snowball's chance in hell. It wasn't any faster than current aircraft, if anything, it seemed a step backwards.



No, it could not match a P-51, P-47 or P-38.




Zipper730 said:


> That said, it seemed better than the XP-55 and XP-56 in terms of stability: From what I remember those designs both had their share of trouble (at least they were lighter though, and the XP-56 did manage to creatively cool a radial and mount it amidships -- hey, let's look on the bright side); regardless, was there requirements for pressurization on the XP-55 and XP-56?



The projected top speed of the XP-56 was 340mph! 

The XP-55 actually flew faster, but wasn't the most stable.

Neither the XP-55 or XP-56 had pressurisation.


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## GrauGeist (Jul 30, 2019)

swampyankee said:


> Just for reference, Germany wasn't unique in this regard: the first flight of the pressurized Boeing 307 was in 1938 (Boeing 307 Stratoliner). _Everybody_ was working on pressurization: the US, the UK, the French, etc.


Junkers successfully tested a pressurized cabin with the Ju49 in 1931, the French in 1932 with the Farman 1000 and then in 1937, Lockheed successfully tested a pressurized fuselage with their XC-35.

But I was under the impression that we were discussing pressurized combat aircraft...


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## Zipper730 (Jul 30, 2019)

wuzak said:


> The V-1710 program predated the existence of the R-1820 and R-1830. The theory of the early 1930s was that air-cooled engines were unsuitable for turbocharging, particularly at high altitudes, where the USAAC wanted their bombers to fly.


That said the H-2470 is basically similar in power output to the RR Griffon right?


> It was about 4-5" wider than an R-3350, 6 or 7" wider than an R-2800.


At least it was flatter...


> The projected top speed of the XP-56 was 340mph!


I thought it was 465...


> Neither the XP-55 or XP-56 had pressurisation.


Why did one require and the other not?


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## Shortround6 (Jul 30, 2019)

Zipper730 said:


> That said the H-2470 is basically similar in power output to the RR Griffon right?


Depends on the Griffon, 
A Griffon would have been a V-2240 in American nomenclature.

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## wuzak (Jul 30, 2019)

Zipper730 said:


> That said the H-2470 is basically similar in power output to the RR Griffon right?



Similar.

But heavier, longer, taller and much less in production.




Zipper730 said:


> I thought it was 465...



465mph was the estimated top speed from the manufacturer. Maybe even the guaranteed top speed.

340mph was the projected (calculated) top speed based on the few flight tests and, possibly, wind tunnel tests. The calculations were done by NACA.

The guaranteed top speed of the XP-54 was, at one stage, 525mph! Its actual top speed was around 400mph, but only with a special finish.




Zipper730 said:


> Why did one require and the other not?



Not a clue.

Note that the XP-55 had a single stage V-1710 with no turbo, and the XP-56 had a 2 stage R-2800, but not turbo, so perhaps it was expected that they would not reach teh altitudes requiring pressurisation.


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## P-39 Expert (Jul 31, 2019)

XBe02Drvr said:


> I found 5-6 hours at FL250 in the Cessna 210 left me feeling pretty wrung out. And that was with the autopilot doing most of the work. I'm sure flying formation in a stick and rudder airplane, searching overhead for bandits, and weaving to stay with the bombers would have me dreaming wistfully of my rack back in the UK. And it feels SO good to take that mask off when you get down to 10K!
> OTOH, the average 8th AF Mustang pilot was a decade younger and most likely more physically fit than I was at the time of my FL adventures.
> Cheers
> Wes


What altitude in your Cessna? Oxygen the whole time?


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## wuzak (Jul 31, 2019)

XBe02Drvr said:


> I found 5-6 hours at *FL250* in the Cessna 210 left me feeling pretty wrung out. And that was with the autopilot doing most of the work. I'm sure flying formation in a stick and rudder airplane, searching overhead for bandits, and weaving to stay with the bombers would have me dreaming wistfully of my rack back in the UK. And it feels SO good to take that mask off when you get down to 10K!
> OTOH, the average 8th AF Mustang pilot was a decade younger and most likely more physically fit than I was at the time of my FL adventures.
> Cheers
> Wes





P-39 Expert said:


> What altitude in your Cessna? Oxygen the whole time?



FL250 = 25,000ft from what I understand.


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## XBe02Drvr (Jul 31, 2019)

wuzak said:


> FL250 = 25,000ft from what I understand.


Affirmative. 25,000 feet indicated altitude with altimeter set at 29.92" Hg, not local surface altimeter setting. Masks go on at 10k, altimeter is reset from local surface value to 29.92 climbing through 18K, and in a puny 300HP piston pounder, it's a long slow slog to FL250. But eastbound it's worth it, as you can generally count on anywhere from 40 to 100+ knots of tailwind. I've seen 350 knots ground speed on the RNAV on a cold winter's night with Aurora B. blazing away off my left wingtip and the distant landscape awash in moonlight. It doesn't get much better than that.
Another advantage to this high altitude flight: a clean airframe like a C210 can glide for nearly a hundred miles (downwind) in case of an engine failure.
Cheers,
Wes

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## BiffF15 (Jul 31, 2019)

XBe02Drvr said:


> Anybody who's had a chamber ride can tell you. Above FL 350-360 breathing 100% O2 with an ambient pressure regulator doesn't supply enough partial pressure of oxygen in the blood to stave off hypoxia, so pressure breathing becomes necessary, a very taxing and exhausting exercise. Above approx 450, ambient pressure is not enough to keep the nitrogen in the blood in solution, and it literally "boils" out, resulting in instant death by eruption. If you're going to operate in that altitude range or higher, you need pressurization or a pressure suit, or both.
> I've flown a couple hundred hours at FL 250 in a non pressurized turbo 210 Cessna, breathing through nose bags, and let me tell you, though it doesn't feel hard at the time, by the end of the day, you feel like you've been run over by a train.
> I can tell you that at 260, I was good for 45 seconds after the mask came off, before the chamber floor came up and kissed my face. And at 370, pressure breathing, I was first in a chamber full of tactical jet aviators to signal "uncle" and have the chamber brought down, after about five minutes. The jet jocks were a little disgruntled that I broke up their little "macho quotient" contest early on.
> Cheers,
> Wes




Wes,

The 45k you reference above is actually at approx 60k and called Armstrong’s Line. The Eagle could get above this easily enough and we were made aware of this during my time in the school house. I know of one now retired 3 star who has been through 75k and and still climbing...

Armstrong limit - Wikipedia

Cheers,
Biff

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## Zipper730 (Jul 31, 2019)

BiffF15
and 
X
 XBe02Drvr
,

I got a question, and this will probably sound stupid, but I'll ask it anyway: If you're breathing in pressurized oxygen and you lose consciousness, do your lungs inflate and pop? Or something else?


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## XBe02Drvr (Jul 31, 2019)

Zipper730 said:


> @BiffF15 and
> X
> XBe02Drvr
> ,
> ...


Your lungs inflate, your chest expands like a balloon, but if the regulator is working correctly (let's hear it for the aircrew equipment guys!), it won't overpressure and rupture your lungs, and the discomfort will make it difficult to drift off to sleep. And the likelihood of pulling enough G at those altitudes to black you out is pretty low. Terrestrial folk don't often think about it, but our ribcage is designed and muscled to expand against resistance, not contract. Exhaling is just the relaxation of the inhaling effort. When an outside force such as a pressure breathing regulator resists our efforts to exhale, we discover how weak we are in that direction.
The only other non - naval aviator in the chamber was some sort of clandestine warfare type (green beret/SEAL/CIA/UDT? - he wasn't talkative), just returning from a tour of staff duty and getting re-qualed to go out in the field. Whatever his billet was, he had to requalify at HALO (High Altitude, Low Opening) parachute insertions from 30+K altitudes, for which he had to get a refresher in the chamber. After they brought the chamber down and let me out, they let the jet jocks talk them into taking the chamber back up so they could carry on their little game of "who can pressure breathe the longest". The spooky guy outlasted all the jet jocks. The folks that ran the chamber said distance swimmers and SCUBA divers were usually the best at pressure breathing.
Cheers,
Wes


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## XBe02Drvr (Jul 31, 2019)

BiffF15 said:


> Wes,
> 
> The 45k you reference above is actually at approx 60k and called Armstrong’s Line. The Eagle could get above this easily enough and we were made aware of this during my time in the school house. I know of one now retired 3 star who has been through 75k and and still climbing...
> 
> ...


Thanks for the update. I don't remember the terminology of Armstrong's limit being used back in 1973, and the altitude numbers they gave were a little lower than what you and Wikipedia quoted. Perhaps a little safety margin to keep testosterone fueled aviators safe and mentally fit to get their precious chariots back aboard the boat?
Cheers,
Wes

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## Zipper730 (Jul 31, 2019)

I was thinking of something else: Was there any way the V-1710-59 could have been designed without it's flaws and been able to produce a higher ACA?


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## XBe02Drvr (Aug 1, 2019)

Zipper730 said:


> I was thinking of something else: Was there any way the V-1710-59 could have been designed without it's flaws and been able to produce a higher ACA?


Of course; any designer with a functioning and properly maintained crystal ball knows ahead of time what features will turn out to be flaws and can avoid incorporating them in the design. That's why everything always works perfectly straight out of the box.
Cheers,
Wes

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## pbehn (Aug 1, 2019)

XBe02Drvr said:


> Of course; any designer with a functioning and properly maintained crystal ball knows ahead of time what features will turn out to be flaws and can avoid incorporating them in the design. That's why everything always works perfectly straight out of the box.
> Cheers,
> Wes


Many design flaws are only considered so in comparison. If someone produced a 3,000 BHP V1700 engine in 1940 or one that ran for 1000 hours without being touched, all other engines would be considered to be flawed. People used to write to the Times when their car did 100,000 miles or ran at 100MPH for 10 minutes without blowing up.

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## P-39 Expert (Aug 1, 2019)

Zipper730 said:


> I was thinking of something else: Was there any way the V-1710-59 could have been designed without it's flaws and been able to produce a higher ACA?


The -59 was the first V-1710 to use the 9.6:1 supercharger step up gears (up from 8.8) to increase critical altitude. Just like the other contemporary V-1710s except for the gear change. Turns out the gears wouldn't support the increased manifold pressure and they wore out too quickly. Fix was to widen the gears but redesign of the accessories casing took almost a year, from the end of '41 to November '42 to get the -59 (now the -83) into a flying airplane. Allison and the Army were still goofing around with backfire screens which reduced power a little but finally discarded those in mid '42 (Sept '42 for turbocharged P-38s). Would have been great if the original gears had worked (backfire screens didn't help) and the -59 would have been available from the end of '41, but the Army would have just negated that by figuring out how to make the P-39 even heavier.

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## Zipper730 (Aug 1, 2019)

P-39 Expert said:


> The -59 was the first V-1710 to use the 9.6:1 supercharger step up gears (up from 8.8) to increase critical altitude. Just like the other contemporary V-1710s except for the gear change.


That I'm aware of: I'm just curious why they had so much difficulty with the higher-speed gear? It wasn't something that's never been done before, the Merlin's had a similar gear-ratio from what I was told.


> Fix was to widen the gears


Are you talking about the teeth?


> Allison and the Army were still goofing around with backfire screens


Why?


> Would have been great if the original gears had worked (backfire screens didn't help) and the -59 would have been available from the end of '41, but the Army would have just negated that by figuring out how to make the P-39 even heavier.


Why would they want to do that?


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## Shortround6 (Aug 1, 2019)

Zipper730 said:


> Are you talking about the teeth?



The power needed to drive a supercharger impeller goes up with the square of the speed of the impeller as a rule of thumb.

An Allison supercharger using 9.6 gears needs 19% more power than one using 8.80 gears. Please remember that the turbocharged engines in the first P-38s used 6.44 gears on the engine supercharger. The supercharger drive had not been intended to handle such power as needed by the higher gear ratios. They needed to make the gears thicker (front to back) to handle the load. However, as mentioned above, the gear case was too thin to handle the thicker gears. The gear case was cast as part of the engine block (crankcase) so new molds had to be designed and built at the casting facilities. Using 9.60 gears the supercharger could easily take over 250hp to drive it. 

Unlike many car engines, aircraft engines are not designed with a lot of extra space or room for "growth" as that means they are too large and heavy in the first models.


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## wuzak (Aug 1, 2019)

Zipper730 said:


> That I'm aware of: I'm just curious why they had so much difficulty with the higher-speed gear? It wasn't something that's never been done before, the Merlin's had a similar gear-ratio from what I was told.



Single stage engines, at least the 45, had a gear ratio of 9.1:1, slightly higher than the 8.8:1 of the earlier V-1710s.

The Merlin XX series had ratios of 8.15:1 (MS/LO) and 9.49:1 (FS/HI).

2 stage Merlins had lower ratios than the XX.

The Merlin's gears were strong enough for those ratios because they were designed for those ratios and the power that the supercharger consumed. 

The V-1710's gears were designed around a lower ratio, which meant that the supercharger consumed less power. From what P-39 Expert said, changing the gears for higher power/speed required a redesign of the accessories casing.

Another factor here is that the V-1710, for most variants, had an impeller diameter of 9", compared to 10.25" for most single stage Merlins. The 47, IIRC, had an impeller of 10.75" or 10.85".

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## Zipper730 (Aug 2, 2019)

Shortround6 said:


> The power needed to drive a supercharger impeller goes up with the square of the speed of the impeller as a rule of thumb.


So 19% for 9.6 vs 8.8 and 222.2% for 9.6 vs 6.44?


> Please remember that the turbocharged engines in the first P-38s used 6.44 gears on the engine supercharger.


I'm guessing they used this lower gearing either because

They expected the turbocharger to take care of the rest and figured the least horsepower taken off the shaft would be best?
When the engine was designed in 1929, they didn't think the higher critical altitudes were important?



> The supercharger drive had not been intended to handle such power as needed by the higher gear ratios. They needed to make the gears thicker (front to back) to handle the load. However, as mentioned above, the gear case was too thin to handle the thicker gears. The gear case was cast as part of the engine block (crankcase) so new molds had to be designed and built at the casting facilities. Using 9.60 gears the supercharger could easily take over 250hp to drive it.


And I guess they didn't realize the casing would have to be strengthened also?



wuzak said:


> Single stage engines, at least the 45, had a gear ratio of 9.1:1, slightly higher than the 8.8:1 of the earlier V-1710s.


Makes sense as they could operate at higher altitudes.


> The Merlin XX series had ratios of 8.15:1 (MS/LO) and 9.49:1 (FS/HI).


And this was to allow more power for low altitude?


> 2 stage Merlins had lower ratios than the XX.


I would have figured they'd have been smaller in diameter but spun faster...


> The V-1710's gears were designed around a lower ratio, which meant that the supercharger consumed less power. From what P-39 Expert said, changing the gears for higher power/speed required a redesign of the accessories casing.


The V-1710 did have a bolt-on provision off the bat for a turbocharger or a secondary supercharger stage, correct?


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## Zipper730 (Aug 2, 2019)

wuzak said:


> FL250 = 25,000ft from what I understand.


That's correct, starting at 18000 feet in the US (some lower amount in Europe), they start using flight-levels which are in blocks of 100 feet so FL180 = 18000 feet, and FL250 = 25000 feet. It goes up to 60000 feet because there's little operating up that high, and since we never fielded the SST, there was no reason to bring it up any higher.


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## Snowygrouch (Aug 2, 2019)

Shortround6 said:


> It was assumed by many in the planning departments/purchasing that the altitudes at which combat took place would keep going up. Which is why the Americans, British, Germans and others had designs/schemes for planes with pressurized cockpits all in the works in 1941-42. However, for a variety of reasons this did not happen with piston engines. At least not to the extent the planners thought.
> ...But some of the problems took too long to solve and the war was fought (mostly) with unpressurized aircraft.



This is all spot on, I have quite a few memos from British air ministry talking about getting Spitfires up to intercept high altiude German aircraft in 1941, it was expected to have to get up to engage at over 40,000 feet, and the reports state that even with Oxygen, the demands on the body caused by low temperature and pressure meant that the pilots would have to be hand-picked. I.e. some people just had a little more resistance due to their natural consitution, and the only way to actually operate at that altitude without a pressure cabin was to find such pilots. These papers say Supermarine regarded fitting out the Spitfire with a pressure cabin as immensely difficult (although they did, but it took a long time and a lot of effort).

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## MIflyer (Aug 2, 2019)

My friend Ward Duncan, maint chief for the 9th PRS,sad that they raised the V-1710 supercharger gear ratio because on the earliest P-38's the turbo was having to wind up to such a high RPM that it was coming apart. The "fins" you can see between the turbos and the cockpit are designed to protect the pilot from a disintegrating turbo wheel.

Above 45,000 ft without cockpit pressurization you have to "pressure breathe" which is a much more difficult situation than normal inhaling and exhaling - it is the reverse of normal. 

A story I have yet to see told is how the RAF and Americans based their oxygen systems on captured German equipment


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## Zipper730 (Aug 3, 2019)

F7F-1 with a two-stage supercharger would be pretty hot-shit: There'd be a need for intercooling, and I'm not sure how much room would exist in the wings for that, but something like the F4U-4 could be done with a chin-scoop.

If I calculated my speed estimates using the cube-rule, I see a substantial benefit. With the exception of the Mach number listing, red will mean inferior in performance, blue will mean superior in performance, and black will mean no difference. The mach number will simply read black if below 0.65, and red above 0.65.

Military Rated Power (as was).............................with 2-stage blower

*Altitude*...*TAS*.............*HP*......*S/C*...................*Altitude*...*TAS*..............*HP*......*S/C*..............*Mach No.*
0'.............368....mph...4200...Low...................0'.............368...mph....4200...Neutral..........0.483
2000'.......376....mph...4200...Low...................2000'.......376...mph....4200...Neutral..........0.497
4000'.......384....mph...4200...Low...................4000'.......384...mph....4200...Neutral..........0.512
.........................................................................4400'.......385...mph....4200...NeutralACA...0.514
6000'.......391....mph...4200...Low...................6000'.......382.1 mph...3920...Neutral..........0.513
8000'.......399....mph...4200...Low...................8000'.......385.9 mph...3800...Low...............0.521
10000'.....397.5 mph...4200...Low...................10000'.....384.5 mph...3800...Low...............0.541
10167'.....407....mph...4200...Low/ACA........................................................................................
12000'.....405....mph...3900...Low...................12000'.....401.5 mph...3800...Low...............0.548
14000'.....403....mph...3590...Low...................14000'.....410.7 mph...3800...Low...............0.568
16000'.....400....mph...3200...Low...................16000'.....420.1 mph...3800...Low...............0.585
16250'.....399....mph...3280...High..................16250'.....422.5 mph...3800...Low................0.589
18000'.....406....mph...3200...High..................18000'.....429.9 mph...3800...Low...............0.603
20000'.....415....mph...3200...High..................20000'.....439.5 mph...3800...Low...............0.622
22000'.....425....mph...3200...High..................22000'.....450.1 mph...3800...Low...............0.642
.........................................................................23200'.....457.5 mph...3800...Low/ACA......*0.656*
23500'.....436....mph...3200...High/ACA..........23500'.....456.6 mph...3720...Low...............*0.655*
24000'.....432....mph...3130...High..................24000'.....448.8 mph...3660...Low................*0.645*
.........................................................................24200'.....453.6 mph...3600...High/Clutch...*0.653*
26000'.....429....mph...2960...High..................26000'.....465.4 mph...3600...High...............*0.675*
28000'.....427....mph...2640...High..................28000'.....475.7 mph...3600...High...............*0.695*
.........................................................................29200'.....484.1 mph...3600...High/ACA......*0.711*
30000'.....425....mph...2400...High..................30000'.....475.2 mph...3440...High...............*0.701*


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## wuzak (Aug 3, 2019)

Zipper730 said:


> Makes sense as they could operate at higher altitudes.



The ratio was 3.4% for the Merlin 45 (9.1 vs 8.8), but the diameter was 7.9% greater (10.25" vs 9.5") so the tip speed was 11.6% higher for the Merlin 45.

That's the main reason it had a greater FTH, but not the only reason.




Zipper730 said:


> And this was to allow more power for low altitude?



The idea of having a 2 speed supercharger was to improve low altitude performance while maintaining, or improving, high altitude performance.




Zipper730 said:


> I would have figured they'd have been smaller in diameter but spun faster...



You'd be wrong.

The 2 stage supercharger for the Merlin required 2 different size impellers because they were fixed to a single shaft and spun at the same speed.

Initial production 60-series engines (61, 63) had an 11.5" 1st stage and 10.1" second stage. Later Merlins (from the 65/66) had 12.0" first stage supercharger.

There were a couple of different ratios for 2 stage engine, with the 61, 63, 70, etc., spinning faster for high altitude performance, while the 65 and 66 had a lower ratio for low(er) altitude performance.

The Packard 2 stage Merlins all seem to have had the 12.0"/10.1" supercharger from the start. The V-1650-3 and -9 had the high altitude gear ratios and the -7 had the low(er) gear ratios.

The Packard Merlins had slightly different ratios to the RR Merlins because they used a different supercharger drive.




Zipper730 said:


> The V-1710 did have a bolt-on provision off the bat for a turbocharger or a secondary supercharger stage, correct?



As the turbocharger could be basically bolted onto any engine, you could say all engines had this provision. Some worked better with it than without.

The main "provision" the V-1710 had to run the turbocharger was a lower supercharger drive ratio for models to be used with a turbo.

EDIT: Corrected the numbers for correct (9.5") V-1710 impeller size.


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## wuzak (Aug 3, 2019)

MIflyer said:


> My friend Ward Duncan, maint chief for the 9th PRS,sad that they raised the V-1710 supercharger gear ratio because on the earliest P-38's the turbo was having to wind up to such a high RPM that it was coming apart. The "fins" you can see between the turbos and the cockpit are designed to protect the pilot from a disintegrating turbo wheel.



I don't believe the supercharger ratio had much to do with the turbocharger overspeeding and flying apart. The problem persisted after the ratio was changed.

The issue is that wastegate regulation was unreliable due to how it was operated. This was changed it later models, and even later was changed to a different system.

The turbocharger was designed to provide sea level pressure to the engine, not for boost, so the engine's supercharger gear ratio was moot regarding the turbo's speed control.

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## Zipper730 (Aug 3, 2019)

wuzak said:


> The ratio was 3.4% for the Merlin 45 (9.1 vs 8.8), but the diameter was 7.9% greater (10.25" vs 9.5") so the tip speed was 11.6% higher for the Merlin 45.
> 
> That's the main reason it had a greater FTH, but not the only reason.


What were the other reasons, reasonably speaking?


> The idea of having a 2 speed supercharger was to improve low altitude performance while maintaining, or improving, high altitude performance.


That adds up


> As the turbocharger could be basically bolted onto any engine, you could say all engines had this provision. Some worked better with it than without.


Oh, I thought it would have been possible to bolt on a second-stage supercharger and the inter-cooling to go with it. How did the airflow requirements of the R-1820 or R-1830 compare with the V-1710.


> I don't believe the supercharger ratio had much to do with the turbocharger overspeeding and flying apart. The problem persisted after the ratio was changed. . . The issue is that wastegate regulation was unreliable due to how it was operated. This was changed it later models, and even later was changed to a different system.


How did it regulate the wastegate?


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## wuzak (Aug 3, 2019)

Zipper730 said:


> What were the other reasons, reasonably speaking?



Better impeller design, better intake.




Zipper730 said:


> Oh, I thought it would have been possible to bolt on a second-stage supercharger and the inter-cooling to go with it.



They could and did. Mainly I was responding to the turbocharger comment.

The 2nd stage of a 2 stage V-1710 was very much a bolt-on, unlike that of a Merlin, or just about any other 2 stage engine.




Zipper730 said:


> How did the airflow requirements of the R-1820 or R-1830 compare with the V-1710.



A little bit less than a V-1710, I would say, but well within the capabilities of the B-series turbocharger.




Zipper730 said:


> How did it regulate the wastegate?



Poorly!

An air line was connected from the compressor discharge to the regulator, but water would freeze in the lines and stop the regulator from working.

Then they changed the line to connect to the exhaust nozzle box.

The final solution was an electronic regulator.


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## Shortround6 (Aug 3, 2019)

wuzak said:


> Poorly!
> 
> An air line was connected from the compressor discharge to the regulator, but water would freeze in the lines and stop the regulator from working.
> 
> ...



I believe the early method was actually to measure the back pressure (exhaust pressure) before the wastegate and control the waste gate so it would maintain a certain value (or range) of exhaust pressure in the system to simulate sea level. It was thought that this would mean a turbo rpm and compressor pressure that would mimic sea level conditions as far as the carb on the engine supercharger was concerned (no real overboosting going on at this point). However, as anyone who as seen a car engine run on a cold day knows, there is water in the products of combustion and this water would freeze the sensor or the control.

I don't know how many changes they went through but the final solution was to measure the air pressure before it entered the carb (which was actually the important part) and then arrange the control box/linkage to open and close the wastegate to give them the desired intake pressure (supposedly sea level air pressure unless overboosting). 

I sure don't want to get into an argument over electric or electronic and the definitions of each so I will leave my contribution as above. The locations if the sensor/s and actuator/s


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## Zipper730 (Aug 3, 2019)

Shortround6 said:


> I believe the early method was actually to measure the back pressure (exhaust pressure) before the wastegate and control the waste gate so it would maintain a certain value (or range) of exhaust pressure in the system to simulate sea level. It was thought that this would mean a turbo rpm and compressor pressure that would mimic sea level conditions as far as the carb on the engine supercharger was concerned (no real overboosting going on at this point). However, as anyone who as seen a car engine run on a cold day knows, there is water in the products of combustion and this water would freeze the sensor or the control.


Ouch...

While this might be a silly question, where is manifold pressure measured from? The fuel-air manifold, or the cylinders? It sounds like it should be what it says on the box, but...


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## Shortround6 (Aug 3, 2019)

I am taking a wild guess but manifold pressure would be measured at the manifold (after the supercharger and/or intercooler on the two stage Merlins) and before the intake port on the cylinder head.

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## Zipper730 (Aug 4, 2019)

I was wondering what fundamental problems existed with the following engines, from a technical standpoint

I-1430
O-1230
X-1800/H-2600
H-3130/3730
While I know that the H-2600 and H-3730 were cancelled because of a desire to focus on radial engines, I'm curious if either had technical flaws that were difficult to work-out?


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## GrauGeist (Aug 5, 2019)

Lycoming's O-1230 may have been rated at 1,200 hp, but it was prone to failure under load and that caused aircraft manufacturers who were interested in using it, and the Army, to back away from the project.


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## wuzak (Aug 5, 2019)

Zipper730 said:


> I was wondering what fundamental problems existed with the following engines, from a technical standpoint
> 
> I-1430
> O-1230
> ...



I-1430: Separate cylinder design, 2 valves per cylinder, smallish capacity and general crappiness.

O-1230: Separate cylinder design, 2 valves per cylinder, smallish capacity and general crappiness.

X-1800/H-2600/H-3130/3730: Liquid cooled in an air-cooled company, sleeve valves. The man driving the project became ill, so went on the back-burner.

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## P-39 Expert (Aug 5, 2019)

What was an "O" configuration for the O-1230?


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## wuzak (Aug 5, 2019)

P-39 Expert said:


> What was an "O" configuration for the O-1230?



Opposed.

I = Inverted, or IV = Inverted Vee (for the I-1430/IV-1430).


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## Shortround6 (Aug 5, 2019)

P-39 Expert said:


> What was an "O" configuration for the O-1230?


Opposed, that is flat.


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## Zipper730 (Aug 5, 2019)

GrauGeist said:


> Lycoming's O-1230 may have been rated at 1,200 hp, but it was prone to failure under load and that caused aircraft manufacturers who were interested in using it, and the Army, to back away from the project.


Why was it prone to failure under load?



wuzak said:


> I-1430: Separate cylinder design, 2 valves per cylinder, smallish capacity and general crappiness.
> 
> O-1230: Separate cylinder design, 2 valves per cylinder, smallish capacity and general crappiness.


What caused the general crappiness? As for the separate cylinder design, I thought that contributed to bulk more than anything else -- I didn't know it undermined performance. As for the number of valves, I'm curious as to how many the V-1710 had...


> X-1800/H-2600/H-3130/3730: Liquid cooled in an air-cooled company


Pratt & Whitney never made a liquid cooled engine? Regardless, that seems more like preference over functionality.


> sleeve valves.


What problems occur with sleeve valves? I do remember that the British used them in the Centaurus and I think it made a lot of smoke or something...


> The man driving the project became ill, so went on the back-burner.


Was he driving both the H-2600 and 3730? Or just one of the two designs?

I also meant to ask this, but what aircraft were the H-3730 designed to power? It seems like a rather massive powerplant...


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## Shortround6 (Aug 5, 2019)

Zipper730 said:


> Why was it prone to failure under load?



For one thing it was trying to make about the same power as an Allison (or Merlin) from an engine about 3/4s the displacement, there is only so much higher rpm can do but........



Zipper730 said:


> What caused the general crappiness? As for the separate cylinder design, I thought that contributed to bulk more than anything else -- I didn't know it undermined performance. As for the number of valves, I'm curious as to how many the V-1710 had...



Separate cylinders mean the crankshaft and crankcase are longer, yes it adds bulk, but it also adds weight and in causes problems with crankshaft flex and torsional vibration. 
Think about rear cylinders firing and trying to twist the crankshaft along it's length. The longer the crankshaft the easier it is to twist it a bit. 
Allison and Merlin used 4 valves per cylinder, you want to know how many the DB 600s and Jumos used, google it. 



Zipper730 said:


> Pratt & Whitney never made a liquid cooled engine? Regardless, that seems more like preference over functionality.



It was preference but remember that P& W made very good air cooled engines. Functionality would mean learning all the ins and outs of the vibration patterns of the liquid cooled engine layouts. P & W spent hundreds of engine test hours figuring (thousands of engineering hours?) out the vibration problems of the R-2800. Making good liquid cooled engines was not as easy as it seems, how much liquid moving how fast is needed to cool the different parts of the engine?



Zipper730 said:


> What problems occur with sleeve valves? I do remember that the British used them in the Centaurus and I think it made a lot of smoke or something...



British used Perseus, Taurus and Hercules engines more than they used the Centaurus and it was far from beer and skittles for quite some time. 




Zipper730 said:


> Was he driving both the H-2600 and 3730? Or just one of the two designs?



He was basically incharge of everything and so could direct the companies efforts. When he fell ill his replacement decided to stick with what P & W knew best, air cooled radials.

They estimated in 1940 that they might have the R-4360 ready in time for the war (of course they didn't know how long the war was going to take) . the Liquid cooled engines were judged to take even longer.


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## stug3 (Aug 5, 2019)

The theory of Survivorship Bias applied to allied aircraft.

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## Zipper730 (Aug 5, 2019)

Shortround6 said:


> For one thing it was trying to make about the same power as an Allison (or Merlin) from an engine about 3/4s the displacement, there is only so much higher rpm can do but........


So they were trying to do too much with too little?


> Separate cylinders mean the crankshaft and crankcase are longer, yes it adds bulk, but it also adds weight and in causes problems with crankshaft flex and torsional vibration.


And this all started because of the requirement for the higher coolant temperatures back with the hyper engine, and they figured that individual cylinders would be needed?


> Allison and Merlin used 4 valves per cylinder, you want to know how many the DB 600s and Jumos used, google it.


They DB-600's used 4.


> It was preference but remember that P& W made very good air cooled engines. Functionality would mean learning all the ins and outs of the vibration patterns of the liquid cooled engine layouts.


So firstly: The devil was in the details? I'm guessing vibration had to do with the greater length of the engine? 

Just to get back to the point: Did they ever design a liquid cooled engine prior to this point?


> P & W spent hundreds of engine test hours figuring (thousands of engineering hours?) out the vibration problems of the R-2800. Making good liquid cooled engines was not as easy as it seems, how much liquid moving how fast is needed to cool the different parts of the engine?


So basically you want the coldest fastest moving fluid to cool the hottest parts and the slowest and warmest to cool the coolest parts?


> He was basically incharge of everything and so could direct the companies efforts. When he fell ill his replacement decided to stick with what P & W knew best, air cooled radials.


So there was a general disinterest in the matter?


> They estimated in 1940 that they might have the R-4360 ready in time for the war


If the H-2600 had been developed, would the H-3730 have likely continued along over the R-4360?


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## wuzak (Aug 6, 2019)

Zipper730 said:


> So they were trying to do too much with too little?



Basically.

The IV-1430 had already been enlarged over the original design based on the "hyper" cylinder, which was 1008ci, IIRC, for an opposed 12.




Zipper730 said:


> And this all started because of the requirement for the higher coolant temperatures back with the hyper engine, and they figured that individual cylinders would be needed?



No.

Maybe it was convenient to put 12 of the "hyper" cylinders together rather than build a monoblock design (like the V-1710, Merlin and DB-60x).

Note that the IV-1430 had a single cylinder head per bank.




Zipper730 said:


> They DB-600's used 4.



So you can use google?




Zipper730 said:


> So firstly: The devil was in the details? I'm guessing vibration had to do with the greater length of the engine?



Yes, partly. The radial engines had 7 or 9 cylinders on each crankshaft throw, while the V-12s had only 2, which meant different vibration characteristics.




Zipper730 said:


> Just to get back to the point: Did they ever design a liquid cooled engine prior to this point?



Yes, but none that went into production.

The R-2060 was one, a liquid cooled radial.




Zipper730 said:


> So basically you want the coldest fastest moving fluid to cool the hottest parts and the slowest and warmest to cool the coolest parts?



You need to balance the coolant flow with the amount of heat that you can extract from the cylinders and reject through the radiator. 

Cooling systems in aircraft were, generally, designed around normal or cruise power, not maximum WEP.

The limits of how long higher power ratings, such as WEP, could be used was due to the limitations of the coolant system.




Zipper730 said:


> So there was a general disinterest in the matter?



It was outside Pratt & Whitney's core competency.




Zipper730 said:


> If the H-2600 had been developed, would the H-3730 have likely continued along over the R-4360?



Given that the R-4360 was essentially chosen over the H-2600, the question is moot. 

The R-4360 was an easier development path for Pratt & Whitney, since the starting point was the R-2800 cylinder.


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## wuzak (Aug 6, 2019)

Shortround6 said:


> British used Perseus, Taurus and Hercules engines more than they used the Centaurus and it was far from beer and skittles for quite some time.



They even used the Sabre more than the Centaurus.

Centaurus development was delayed because Bristol was busy fixing and improving the Hercules.


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## XBe02Drvr (Aug 6, 2019)

wuzak said:


> Maybe it was convenient to put 12 of the "hyper" cylinders together rather than build a monoblock design


P&W was a radial engine company. Single separate cylinders were their stock in trade. Monoblock design was foreign to them and too devilishly full of details that had taken other companies years and iterations to learn.
Cheers,
Wes


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## wuzak (Aug 6, 2019)

XBe02Drvr said:


> P&W was a radial engine company. Single separate cylinders were their stock in trade. Monoblock design was foreign to them and too devilishly full of details that had taken other companies years and iterations to learn.
> Cheers,
> Wes



Not talking about Pratt & Whitney.

The engines based on the "hyper" cylinder were separate cylinder construction - the Continental IV-1430 and the Lycoming O-1230/H-2470. 

I believe the P&W X-1800/H-2600, etc, were monoblock designs.


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## GrauGeist (Aug 6, 2019)

Zipper730 said:


> Why was it prone to failure under load?


Because on the bench, it's performance looked good, but once it was installed in the Vultee and put through performance testing, the engine suffered from excessive detonation (until higher grade fuel was provided) as well as cracks in the crankcase and bearing failure.


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## Zipper730 (Aug 6, 2019)

wuzak said:


> Basically.
> 
> The IV-1430 had already been enlarged over the original design based on the "hyper" cylinder, which was 1008ci, IIRC, for an opposed 12.


The 1008 arrangement was also a V from what I recall.


> No. . . .Maybe it was convenient to put 12 of the "hyper" cylinders together rather than build a monoblock design (like the V-1710, Merlin and DB-60x). . . . Note that the IV-1430 had a single cylinder head per bank.


They really should have redrawn the contract as technology advanced to allow for monoblock construction -- actually, why didn't they?


> So you can use google?


That's how I got the information, you said don't ask, use google. I used google.


> Yes, partly. The radial engines had 7 or 9 cylinders on each crankshaft throw, while the V-12s had only 2, which meant different vibration characteristics.


Which they'd have to work out.


> Yes, but none that went into production.


But they would have a body of knowledge on radial engines, to some extent, anyway.


> The R-2060 was one, a liquid cooled radial.


I'll see what I can find online


> You need to balance the coolant flow with the amount of heat that you can extract from the cylinders and reject through the radiator.


Understood.


> Cooling systems in aircraft were, generally, designed around normal or cruise power, not maximum WEP.


So the key is providing proper cooling for cruise power, but being able to cool the engine enough for WEP settings?


> It was outside Pratt & Whitney's core competency.


I'm actually curious why the USN was so interested in developing the design at all. That surprised me more than anything else.


> Given that the R-4360 was essentially chosen over the H-2600, the question is moot. . . . The R-4360 was an easier development path for Pratt & Whitney, since the starting point was the R-2800 cylinder.


What I was curious about was basically, from an academic standpoint, is basically...

If the H-2600 was given the go-ahead: Would the R-2800 have likely been given the go-ahead or been cancelled?
If the H-2600 was given the go-ahead: Would the H-3730 likely been given the go-ahead, essentially, by extension?
For the R-4360 to have been given the go-ahead, would it have required the cancellation of the R-4360 radial design?


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## Shortround6 (Aug 6, 2019)

Zipper730 said:


> They really should have redrawn the contract as technology advanced to allow for monoblock construction.



Mono block construction dated to WW I, see Hispano Suiza V-8s.
You seem to still be confused as to who was designing what. 
Continental and to some extent, Lycoming were building what the Army told them to build. If the Army said "design separate cylinder engines" that is what they did. 
If they had designed monoblock engines the Army would have said "that is not what we ordered, we are not paying for it". 
When all the Army was ordering was 2 cylinder test rigs it didn't make much difference. When it came time for the 12 cylinder versions things went to crap in a hurry. 



Zipper730 said:


> What I was curious about was basically, from an academic standpoint, is basically...
> 
> If the H-2600 was given the go-ahead: Would the R-2800 have likely been given the go-ahead or been cancelled?
> If the H-2600 was given the go-ahead: Would the H-3730 likely been given the go-ahead, essentially, by extension




If you cancel the R-2800 (which was earlier in timing than the H-2600) you give Wright market domination in the 1500 hp and market for several years (maybe 4 or 5). 

According to most sources, Mead became interested in Sleeve valves at some point in 1937. Work on the R-2600 (yes R-2600) began in August 1936. This would be P & W 4th two row radial and that added to their experience with single row engines (at least 4 different ones). However upon learning that Wright was building an R-2600 in March of 1937 P&W modified their engine to 2804 cubic in to top Wright. The R-2800 had at least year and probably more head start on any of the Liquid cooled P & W engines and given P & W expertise in air cooled cylinders (and the fact that the R-2800 used the same size cylinders but not the same construction as the R-2180) that lead may have been even bigger. 

In any event it is claimed that P & W _Estimated_ the date for start of mass production for the X-1800 as some time in 1942. Jan 1942 saw the A series R-2800 being phased out of Production by P & W (none would be built in Feb) and the single stage and two stage R-2800s being phased in, Ford was also building B series R-2800s in Jan ( a few dozen) nad would stop Building A series engines by April (which would see 463 B series engines built). 
Canceling the R-2800 in favor of the H-2600 would have been a catastrophe for both P & W and the US war effort even if the H-2600 had worked and even if it entered production in the 2nd half of 1942.


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## wuzak (Aug 6, 2019)

Shortround6 said:


> According to most sources, Mead became interested in Sleeve valves at some point in 1937.



It seems to have happened during a tour of UK aero engine manufacturers. Mead was impressed by the prototype Sabre.


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## Zipper730 (Aug 7, 2019)

Shortround6 said:


> Continental and to some extent, Lycoming were building what the Army told them to build. If the Army said "design separate cylinder engines" that is what they did. . . . If they had designed monoblock engines the Army would have said "that is not what we ordered, we are not paying for it".


No, I get that. I just think the US Army should have re-written the contract when time came to go to 12-cylinders. I'm not sure how easy it was to deduce the effect of two cylinders in a test-rig versus twelve cylinders.


> If you cancel the R-2800 (which was earlier in timing than the H-2600) you give Wright market domination in the 1500 hp and market for several years (maybe 4 or 5).


I asked if the H-2600 had been given the go-ahead would the R-2800 have proceeded.


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## sazabi2001 (Aug 7, 2019)

I think the top ally ACEs flew the P38 & P39... So why not Merlin-ed them like P51?


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## wuzak (Aug 7, 2019)

Zipper730 said:


> I asked if the H-2600 had been given the go-ahead would the R-2800 have proceeded.



The R-2800 and H-2600 proceeded at the same time historically. The H-2600 would never have taken precedence over the R-2800.


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## swampyankee (Aug 7, 2019)

sazabi2001 said:


> I think the top ally ACEs flew the P38 & P39... So why not Merlin-ed them like P51?



The Soviet P-39 successes were at low altitudes, where the Allison engine performed quite well. The P-38 would require a lot of rework to fit Merlins and maintain its high-altitude performance. Also, the P-39 would require work to integrate a new engine with its driveshaft. I think the Allison had a different firing order, so it would have different vibration characteristics.


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## GrauGeist (Aug 7, 2019)

sazabi2001 said:


> I think the top ally ACEs flew the P38 & P39... So why not Merlin-ed them like P51?


To add to Swampyankee's explanation, it also takes time to refit an airframe to accept a new engine.
The P-38 and P-39 were critical fighters in the early stages of the war and such a design change would stop production of the much needed aircraft.


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## sazabi2001 (Aug 7, 2019)

swampyankee said:


> The Soviet P-39 successes were at low altitudes, where the Allison engine performed quite well. The P-38 would require a lot of rework to fit Merlins and maintain its high-altitude performance. Also, the P-39 would require work to integrate a new engine with its driveshaft. I think the Allison had a different firing order, so it would have different vibration characteristics.




From Wiki:

Bell P-63 Kingcobra - Wikipedia 

"The first prototype, 41-19511, flew for the first time on 7 December 1942. It was destroyed on 28 January 1943 when its landing gear failed to extend. The second prototype, 41-19512, followed on 5 February 1943. It, too, was destroyed, this time due to an engine failure. The Merlin-engined 42-78015 (as Merlins were primarily needed for the P-51 Mustang) was delivered with another Allison instead, a -93, which had a war emergency rating of 1,500 hp (1,120 kW) at sea level, making this prototype one of the fastest Kingcobras built, attaining 421 mph (678 km/h) at 24,100 ft (7,300 m).“

Seems like there was an attempt for Merlin KingCobra, and even without the Merlin engine inside yet that was the fastest KingCobra ever built.

==========

For the P38, I think it is a bit pointless for a Merlin version.

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## sazabi2001 (Aug 7, 2019)

GrauGeist said:


> To add to Swampyankee's explanation, it also takes time to refit an airframe to accept a new engine.
> The P-38 and P-39 were critical fighters in the early stages of the war and such a design change would stop production of the much needed aircraft.



I think P39 never 'critical' to the American and British.


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## P-39 Expert (Aug 7, 2019)

swampyankee said:


> The Soviet P-39 successes were at low altitudes, where the Allison engine performed quite well. The P-38 would require a lot of rework to fit Merlins and maintain its high-altitude performance. Also, the P-39 would require work to integrate a new engine with its driveshaft. I think the Allison had a different firing order, so it would have different vibration characteristics.


For the bazillionth time, the vast majority of P-39s received by the Soviets (N and Q models) were not altitude limited. As the Soviets configured them (no wing guns etc) they had service ceilings over 38500' and would climb at just under 2000fpm at 25000'. This is substantially above the FW190A and about the same as the Bf109G. And at 25000' better than a P-47B/C or P-38F/G.

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## Zipper730 (Aug 7, 2019)

sazabi2001 said:


> I think the top ally ACEs flew the P38 & P39...


I don't know about the P-39, but the P-38 was flown by several high scoring aces. I'm not sure how many scored well in the ETO and how many scored in the PTO, but Richard Bong scored in the Pacific.


> So why not Merlin-ed them like P51?


They had toyed with the idea of putting a Merlin in the P-38, but I forgot the reason. The P-39 had to do with a limit on the number of aircraft.


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## P-39 Expert (Aug 7, 2019)

P-39 couldn't take the Merlin because of different locations for the engine mounts and the Merlin didn't have the remote reduction gear. Would have taken a major reconfiguration by Rolls Royce or Bell to get the Merlin to fit.

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## GrauGeist (Aug 7, 2019)

sazabi2001 said:


> I think P39 never 'critical' to the American and British.


The P-39 was critical to the US in the Pacific and even moreso to the Soviet Union.

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## Kevin J (Aug 7, 2019)

GrauGeist said:


> The P-39 was critical to the US in the Pacific and even moreso to the Soviet Union.


Perfect for the USSR. The only fighter available in the South Pacific in early 1942 when the Japanese were expanding their defensive perimeter, the P-40 was better of course.


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## P-39 Expert (Aug 7, 2019)

At what?


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## pbehn (Aug 7, 2019)

P-39 Expert said:


> At what?


Preventing back strain.

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## GrauGeist (Aug 7, 2019)

The P-39 was able to prove itself against the A6M ad long as they fought at lower altitudes.

Where the P-39 proved to be invaluable, however, was in the ground attack role. It literally saved Henderson field against a Japanese counter-attack and it sent many a Japanese troop transport to the bottom. It also was a crucial factor in the Aleutian theater early on, too.

It provided an irreplaceable platform at a precarious time in the war.

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## P-39 Expert (Aug 8, 2019)

GrauGeist said:


> The P-39 was able to prove itself against the A6M ad long as they fought at lower altitudes.
> 
> Where the P-39 proved to be invaluable, however, was in the ground attack role. It literally saved Henderson field against a Japanese counter-attack and it sent many a Japanese troop transport to the bottom. It also was a crucial factor in the Aleutian theater early on, too.
> 
> It provided an irreplaceable platform at a precarious time in the war.


And most of those Japanese killed at Henderson were from the .30 caliber guns that I so dislike.

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## drgondog (Aug 8, 2019)

sazabi2001 said:


> From Wiki:
> 
> Bell P-63 Kingcobra - Wikipedia
> 
> ...


There was no US role for either the P-39 or the P-63. They were both too limited in range for escort or recon, there was no interception mission that the P-38 was not capable of fulfilling. In 1943 the emerging XP-51F with merlin 1650-3 was FAR more capable than the P-63 at all altitudes, much faster, climbed much better, had almost as much range as the P-51B/D.
Then the most important reason of all (for both the P-39 and P38) is that ZERO Packard Merlin 1650-3/-7 were Available to any US aircraft except the Mustang. Packard never had the capacity.

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## P-39 Expert (Aug 8, 2019)

Except that the P-38 did not see combat until December '42 (call it '43) and the P-51B did not see combat until December'43 (call it '44). Something (P-39 and P-40) had to hold the line in '42. There was really no high altitude escort until the P-47 reached combat in May '43. The original P-38s in England got sent to the Med in late '42 for Torch.

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## drgondog (Aug 9, 2019)

P-39 Expert said:


> Except that the P-38 did not see combat until December '42 (call it '43) and the P-51B did not see combat until December'43 (call it '44). Something (P-39 and P-40) had to hold the line in '42. There was really no high altitude escort until the P-47 reached combat in May '43. The original P-38s in England got sent to the Med in late '42 for Torch.



Agree your comments but the P-39 was dead with respect to future of both CAS/TAC in early 1943 when the decision was made by TAC-HQ to replace both the P-40 and P-39 with the P-51A, then P-51B when the Merlin Mustang was in production. My comments were focused on why their was no real consideration to re-design the P-39 to try to squeeze the Merlin into the airframe. Either the Allison 2s/2stage or the Merlin made the P-63 with extra fuselage length and wing change required for CG purposes and even though the P-63 was coming in parallel with the P-51A, it still had serious deficiencies in external bomb load and range.

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## swampyankee (Aug 9, 2019)

drgondog said:


> Agree your comments but the P-39 was dead with respect to future of both CAS/TAC in early 1943 when the decision was made by TAC-HQ to replace both the P-40 and P-39 with the P-51A, then P-51B when the Merlin Mustang was in production. My comments were focused on why their was no real consideration to re-design the P-39 to try to squeeze the Merlin into the airframe. Either the Allison 2s/2stage or the Merlin made the P-63 with extra fuselage length and wing change required for CG purposes and even though the P-63 was coming in parallel with the P-51A, it still had serious deficiencies in external bomb load and range.



Because of its configuration, the P-39 had serious problems with growth, in general, and in re-engining. Since the size of a drive shaft is dictated by vibration properties and torque, and the path of the shaft has to be straight from the engine output to the propeller hub. This may require modifying the pilot so the shaft can pass through his chest or abdomen (not recommended) or modifying the Merlin for a remote gearbox (recommended). How difficult this would be, I have no knowledge. Obviously, a gearbox would also be needed. The Merlin and the Allison had different firing orders, which would have made differences in the forcing function for the shaft, which would require, at a minimum, analysis and testing. A Merlin P-39 would require, at a minimum, significant redesign of the fuselage center section and transmission from the engine to propeller; while this redesign could be done without slowing down production, introducing this into production would require new production tooling.

You still have an aircraft with severely constrained internal fuel capacity (the engine is right where you want to put fuel tanks) and a tendency to have its center of gravity move aft as combat proceeds, not infrequently resulting in flight characteristics that are somewhat unpleasant. While the P-39 was not as terrible as some have made out, it was at least a half-generation behind the P-51 (and F4U and P-47) and even the derivative design, the P-63, was no advance over the P-51 (and F4U and P-47).

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## wuzak (Aug 9, 2019)

swampyankee said:


> Because of its configuration, the P-39 had serious problems with growth, in general, and in re-engining. Since the size of a drive shaft is dictated by vibration properties and torque, and the path of the shaft has to be straight from the engine output to the propeller hub. This may require modifying the pilot so the shaft can pass through his chest or abdomen (not recommended) or modifying the Merlin for a remote gearbox (recommended). How difficult this would be, I have no knowledge. Obviously, a gearbox would also be needed. The Merlin and the Allison had different firing orders, which would have made differences in the forcing function for the shaft, which would require, at a minimum, analysis and testing. A Merlin P-39 would require, at a minimum, significant redesign of the fuselage center section and transmission from the engine to propeller; while this redesign could be done without slowing down production, introducing this into production would require new production tooling.
> 
> You still have an aircraft with severely constrained internal fuel capacity (the engine is right where you want to put fuel tanks) and a tendency to have its center of gravity move aft as combat proceeds, not infrequently resulting in flight characteristics that are somewhat unpleasant. While the P-39 was not as terrible as some have made out,



The Merlin could have been modified to have a direct output shaft rather than a reduction gear.

How long it would take to get such a modification into production I do not know.

You definitely wanted to use crankshaft speed at least, to minimise the size of the driveshaft which, as you pointed out, dictated by torque.

The Griffon in the Rolls-Royce Flying Test Bed had an output lower than the crankshaft centreline, being driven by a step up spur gear set (output shaft speed faster than crankshaft).


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## P-39 Expert (Aug 9, 2019)

swampyankee said:


> Because of its configuration, the P-39 had serious problems with growth, in general, and in re-engining. Since the size of a drive shaft is dictated by vibration properties and torque, and the path of the shaft has to be straight from the engine output to the propeller hub. This may require modifying the pilot so the shaft can pass through his chest or abdomen (not recommended) or modifying the Merlin for a remote gearbox (recommended). How difficult this would be, I have no knowledge. Obviously, a gearbox would also be needed. The Merlin and the Allison had different firing orders, which would have made differences in the forcing function for the shaft, which would require, at a minimum, analysis and testing. A Merlin P-39 would require, at a minimum, significant redesign of the fuselage center section and transmission from the engine to propeller; while this redesign could be done without slowing down production, introducing this into production would require new production tooling.
> 
> You still have an aircraft with severely constrained internal fuel capacity (the engine is right where you want to put fuel tanks) and a tendency to have its center of gravity move aft as combat proceeds, not infrequently resulting in flight characteristics that are somewhat unpleasant. While the P-39 was not as terrible as some have made out, it was at least a half-generation behind the P-51 (and F4U and P-47) and even the derivative design, the P-63, was no advance over the P-51 (and F4U and P-47).


I don't believe the P-39 needed the Merlin (especially with the mods necessary) as much as it needed a weight reduction in those early planes with the -35 engine with 8.8 gears. Those models had empty weights of 5409#-5462# and with a 1700# load would have weighed 7100# to 7162# and would have performed just fine for '41 and '42, see the P-39C at 7075# in wwiiaircraftperformance.org. The P-39M/N/Q with the later -85 engine with the 9.6 gears didn't really need a weight reduction but sure didn't need the drag of the gondola .50s on the Q. Growth of the P-39 could have consisted of the -93 engine with mechanical second stage supercharger (in production from April '43) and, yes, substitution of 50 gallons of fuel in place of wing guns. No major structural changes were necessary and the result would have been a two stage P-39(R?) with 170 gallons of internal fuel at a weight under 8000#. Quite a hot rod considering the P-63 weighed 8900# and the P-51B weighed 9600# and didn't reach combat until December '43 (call it '44).
The P-63 was another puzzle, why expand the wing size to 248sqft and only put 132 gallons if fuel in it? Remove the drag inducing gondola .50 caliber MGs and virtually the entire wing except landing gear would be available for fuel. And three drop tank locations. Without the wing guns the P-63 was competitive with the P-51B. I guess the Russians didn't need more fuel. Any of these P-39/63s would easily outclimb the F4U or P-47 of 1943 at all altitudes. The AAF just didn't seem to want the obvious improvements available to the P-39.


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## XBe02Drvr (Aug 9, 2019)

P-39 Expert said:


> The AAF just didn't seem to want the obvious improvements available to the P-39.


They just didn't believe there could be a silk purse hiding in that sow's ear. Why throw good money after bad?
Can you spell S K E P T I C A L?
Cheers,
Wes


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## P-39 Expert (Aug 9, 2019)

Right, Bell only built 9500+ P-39s and another 3300 P-63s. That's a lot of bad money.

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## pinsog (Aug 9, 2019)

Where was the turbocharger located on the XP-39?


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## Kevin J (Aug 9, 2019)

P-39 Expert said:


> Right, Bell only built 9500+ P-39s and another 3300 P-63s. That's a lot of bad money.



Bell had one very very satisfied customer in the USSR, who preferred their product over the Curtis's one. Just think, without the USSR, maybe no decent Bell helicopters in the Korean and Vietnamese wars.


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## wuzak (Aug 9, 2019)

pinsog said:


> Where was the turbocharger located on the XP-39?



Under the engine.


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## pinsog (Aug 9, 2019)

wuzak said:


> Under the engine.


Thank you. 

I think adding a turbocharger to a P39 would be far easier than changing to a Merlin. 

Put the turbocharger back under the engine behind the radiator. Delete wing intakes for radiator and replace them with another fuel tank in the wing roots. Belly scoop replaces wing root intakes. Intercooler on the sides behind engine with scoops like on P38. Probably be slower down low but should still be really fast up high. 2 50’s and a 20mm. Wouldnt be the best against fighters due to engine location, but should be great against bombers with engine in the back.


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## Shortround6 (Aug 9, 2019)

There were not a bunch of Merlins sitting around in crates waiting to be used. Allocations of engines were often made months if not a year prior to actual construction/installation in an aircraft. The US used up the vast majority of it's initial allotment of Merlin engines (3000 out of the first 9000 made) on the P-40F and L, there may have been a few hundred or so that the US let the British have, exact number of spares is not common knowledge. Neither is the numbers involved in the follow up contracts. In 1942 and early 1943 every Merlin powered P-39 is a Merlin powered P-40 NOT built. For the Merlin P-38 fans every early Merlin P-38 is TWO Merlin P-40s not built. That contract was fulfilled in the Spring of 1943 and Packard went on to build well over 40,000 more Merlins for both the British Commonwealth and the US.

There was a very real shortage of two stage Merlins in the late spring, early summer of 1943 with several hundred P-51 airframes waiting for engines. Packard was cranking out single stage engines at a rate over 35% higher than over the winter of 1942/43 but most of those were going to the British.

It is going to take a lot of rework to get a Merlin into a P-39, the motor mounts are the least of the problems. You need to change the supercharger cover which is the carb mount and inlet elbow so you can use a downdraft carb. otherwise you are mucking about with the radiator flap/door and a bottom inlet that is guaranteed to pick up every rock, pebble, piece dirt, stray nut or bolt on the whole airfield. You need to change the sizes of the radiator and oil coolers and that is for a single stage Merlin. The list goes on.

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## Shortround6 (Aug 9, 2019)

pinsog said:


> Thank you.
> 
> I think adding a turbocharger to a P39 would be far easier than changing to a Merlin.
> 
> Put the turbocharger back under the engine behind the radiator. Delete wing intakes for radiator and replace them with another fuel tank in the wing roots. Belly scoop replaces wing root intakes. Intercooler on the sides behind engine with scoops like on P38. Probably be slower down low but should still be really fast up high. 2 50’s and a 20mm. Wouldnt be the best against fighters due to engine location, but should be great against bombers with engine in the back.



Bell made two mock ups of quicky installations of turbos on existing P-39s, There was* NO Probably be slower down low. *They _were both _30-40mph slower under 15,000ft. Maybe a better more integrated job could have done better but getting high altitude performance at the cost of being out run by Zeros at low altitude doesn't really gain you much.

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## pinsog (Aug 9, 2019)

Shortround6 said:


> Bell made two mock ups of quicky installations of turbos on existing P-39s, There was* NO Probably be slower down low. *They _were both _30-40mph slower under 15,000ft. Maybe a better more integrated job could have done better but getting high altitude performance at the cost of being out run by Zeros at low altitude doesn't really gain you much.


Agreed. Any pics of those? I assume you mean later model P39’s like P39D or later?


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## Shortround6 (Aug 9, 2019)

Somewhere in many threads on the P-39 there is at least one of them, One mock up put the turbo and intercooler in pod on the centerline replacing the drop tank or bomb.
It is a mock up so they never fitted the intended exhaust manifolds/pipes.






The second one was truly ugly with most of the hardware over the engine (blocking the rear view) with a large scoop on each side (Dumbo ears).


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## pinsog (Aug 9, 2019)

Shortround6 said:


> Somewhere in many threads on the P-39 there is at least one of them, One mock up put the turbo and intercooler in pod on the centerline replacing the drop tank or bomb.
> It is a mock up so they never fitted the intended exhaust manifolds/pipes.
> 
> 
> ...


That defies explanation. Did Bell employ engineers? Did they fire them and replace them with children with crayons? That looks like the losing entry to ‘draw a new Star Wars ship’ in a kindergarten class.


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## swampyankee (Aug 9, 2019)

pinsog said:


> That defies explanation. Did Bell employ engineers? Did they fire them and replace them with children with crayons? That looks like the losing entry to ‘draw a new Star Wars ship’ in a kindergarten class.



The XP-39's turbo installation was, as I recall _very_ bad, as in with such high drag that removing it improved performance and operational ceiling. Turbo installations of the time were quite bulky, as evidenced by the P-47 or, more closely applicably, the P-38. Maybe Bell did have trouble getting engineers. After all, there was a bit of demand for engineers at the time, what with the P-51, F4U, TBF, P-47, ....


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## Shortround6 (Aug 10, 2019)

pinsog said:


> That defies explanation. Did Bell employ engineers? Did they fire them and replace them with children with crayons? That looks like the losing entry to ‘draw a new Star Wars ship’ in a kindergarten class.


It was an attempt to fit a turbo with the least amount of change to the existing aircraft (disruption of production) but fitting turbos in small aircraft was not easy.


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## Zipper730 (Aug 10, 2019)

Shortround6 said:


> I am taking a wild guess but manifold pressure would be measured at the manifold (after the supercharger and/or intercooler on the two stage Merlins) and before the intake port on the cylinder head.


It instinctively sounds right, but things aren't always how you'd expect.

Also, this is something that I'm not sure I got a clear answer on: Was it known at the time (not now) that a higher-geared supercharger (i.e. one for higher altitude) would need an exponential amount of power (and structural strength) to provide the forces to drive it by engineers at the time?


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## Zipper730 (Aug 10, 2019)

Now this is kind of just being silly, so it sounds completely retarded, I won't be all that surprised. I remember the sidewinder-supercharger arrangement seen on the F4U-5, and I'm wondering when the first time somebody thought of that idea was, and if anybody thought of a turbocharger that ran sideways? That or a twin-turbo?


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## XBe02Drvr (Aug 10, 2019)

Zipper730 said:


> Was it known at the time (not now) that a higher-geared supercharger (i.e. one for higher altitude) would need an exponential amount of power (and structural strength) to provide the forces to drive it by engineers at the time?


When you're dealing with a compressible fluid such as air, just about all parameters are going to be exponential in nature. That's never been a secret. Now a precise determination of the strength and likely breaking point of those gears may have required more calculating power than was available in those pre-computer days. Also, all humans, even mighty engineers, are capable of "brain farts".
Cheers,
Wes


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## pinsog (Aug 10, 2019)

Shortround6 said:


> It was an attempt to fit a turbo with the least amount of change to the existing aircraft (disruption of production) but fitting turbos in small aircraft was not easy.


My response was tongue in cheek, but I know you know that. The pic you showed, in my opinion, is such a poor design for adding a turbo that it really, to me, seems like a ‘why even bother’ attempt. Literally ‘let’s glue a turbocharger to the belly’ sounds like a joke one of the engineers told at the bar after too many beers. But I do understand they were lacking space in an already small airframe and didn’t want to slow production


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## wuzak (Aug 11, 2019)

Zipper730 said:


> Also, this is something that I'm not sure I got a clear answer on: Was it known at the time (not now) that a higher-geared supercharger (i.e. one for higher altitude) would need an exponential amount of power (and structural strength) to provide the forces to drive it by engineers at the time?



Yes.

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## wuzak (Aug 11, 2019)

Zipper730 said:


> Now this is kind of just being silly, so it sounds completely retarded, I won't be all that surprised. I remember the sidewinder-supercharger arrangement seen on the F4U-5, and I'm wondering when the first time somebody thought of that idea was, and if anybody thought of a turbocharger that ran sideways? That or a twin-turbo?



There is this drawing from Flight of a Merlin fitted with turbos.
Rolls-Royce Merlin XX Turbo-Supercharger Cutaway Drawing | #4956259 | Media Storehouse Print Store 

Not sure if it was an actual Rolls-Royce proposal, or something Flight came up with on their own.

The B-29 had two turbochargers, one either side of the nacelle, behind the engine.


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## P-39 Expert (Aug 11, 2019)

No turbo for the P-39, best thing that ever happened to it was deleting the turbo. To improve performance just delete some non-essential equipment to make them lighter (.30 cal wing guns and nose armor plate) until the mechanical second stage was in production in April '43.
The internal supercharger step-up gears could accommodate ratios from 6:1 up to 11.6:1 by simply changing the number of teeth in the drive gear and the driven gear. The two stage engines (turbo and mechanical) used lower ratios (6.44, 7.48 and 8.1) since the second stage was supplying sea level air to the internal stage. Single stage engines used the 8.8 and 9.6 gears and it was hoped that the 9.6 gears could be introduced in late '41 to increase critical altitude from 12000' to 15000' and provide about 100 additional horsepower above about 9000' as compared to the 8.8 gears. The 9.6 gears proved unable to take the increased manifold pressure and could not complete the standard (for the U.S) 150 hour test. Possibly because port backfire screens were still in use (until mid '42) that reduced the manifold pressure at the port into the cylinder. Had these backfire screens been deleted the unrestricted flow from the supercharger to the intake ports may have reduced the load on the gears enough for them to pass the test. But the backfire screens were not eliminated until mid'42 while Allison was in the middle of redesigning the gear housing to accommodate wider gears to handle the increased pressure. The wider gears were in production from August '42 and were in production P-39Ms from November '42. So about a year was lost fixing the 9.6 gear problems.

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## XBe02Drvr (Aug 11, 2019)

Shortround6 said:


> One mock up put the turbo and intercooler in pod on the centerline replacing the drop tank or bomb.
> It is a mock up so they never fitted the intended exhaust manifolds/pipes.


Hey it's a P39J (J for jet boosted)! They stole one of the XP59's engines to make a V1 killer out of a 'cobra!


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## pinsog (Aug 11, 2019)

XBe02Drvr said:


> Hey it's a P39J (J for jet boosted)! They stole one of the XP59's engines to make a V1 killer out of a 'cobra!


I sure like your idea better than the one they came up with! (As long as I don’t have to fly it)


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## Zipper730 (Aug 11, 2019)

XBe02Drvr said:


> When you're dealing with a compressible fluid such as air, just about all parameters are going to be exponential in nature. That's never been a secret. Now a precise determination of the strength and likely breaking point of those gears may have required more calculating power than was available in those pre-computer days.


So you think they miscalculated, or in some way, got careless?



wuzak said:


> Yes.


Did they miscalculate how much the shaft and gears could take, or did they get careless?


> There is this drawing from Flight of a Merlin fitted with turbos.


I have the image here



[/quote]Did Allison ever think of that kind of thing?


> The B-29 had two turbochargers, one either side of the nacelle, behind the engine.


I thought the turbines were pointed either down or aft at an angle...


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## wuzak (Aug 11, 2019)

Zipper730 said:


> Did Allison ever think of that kind of thing?



I doubt it.

Firstly because a single B-series turbo was sufficient for the V-1710 and, secondly, the exhaust and turbo installation wasn't in their scope, instead falling to the airframe manufacturer.


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## swampyankee (Aug 11, 2019)

wuzak said:


> I doubt it.
> 
> Firstly because a single B-series turbo was sufficient for the V-1710 and, secondly, the exhaust and turbo installation wasn't in their scope, instead falling to the airframe manufacturer.


 Why the turbo installation fell to the airframe manufacturer, not the engine company is one of the mysteries of WWII-era procurement.


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## Big Jake (Aug 11, 2019)

Shortround6 said:


> Very few bombers could carry the same weight of "small" bombs as large ones. _Small being under 250lbs_. even an He 111 dropped from 4400lbs carrying eight 250kg bombs to 3520lbs carrying thirty two 50kg bombs and they managed to stuff four 50kg bombs in each 250kg bomb cell.
> 
> Hanging them on individual racks really sucks up room. In part due to the needs of hoisting bombs into position and the needs of the armorers to work around the bombs fitting fuses and safety wires.
> 
> ...



B-25 - the prohibition on pivot turns has nothing to do with CG. The B-25 has no nose wheel steering and the wheel is free swiveling. You steer the B-25 by differential engine power and very delicate little application of brakes. If you get the nose wheel off of the direction that you are traveling, it will swing to the side and you'll be hard pressed to get it back. If you do a pivot then you'll just have to keep going in circles or have a ground crew member come with a tow bar and get the nose wheel point in the right direction for you. All of the above is on hard surfaces, never mind soft surface.


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## XBe02Drvr (Aug 11, 2019)

Big Jake said:


> You steer the B-25 by differential engine power and very delicate little application of brakes.


Also the T34 and the Be1900 (after the useless, treacherous, maintenance nightmare OEM pneumatic nosewheel steering was consigned to the dustbin where it belonged). The Be99 had direct linkage steering off the rudder pedals, lightplane style, but you could easily overpower it with differential thrust. This can be useful if you find yourself on a slick surface with nil braking action, as sometimes happens when you're flying freight into the back country on the back side of the clock. Beta thrust is a lifesaver.
Cheers,
Wes

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## Big Jake (Aug 11, 2019)

swampyankee said:


> Why the turbo installation fell to the airframe manufacturer, not the engine company is one of the mysteries of WWII-era procurement.



Installation of the turbo fell under the subject of overall aircraft general arrangement and had to do with allocation of space and overall systems arrangement. Different designers adopted different solutions. Some installed the turbo right behind the engine (P-37), some on top of the tail boom (P-38) and some in the tail (P-47). In the B-17 they are behind the engines, in the B-29 on the side.

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## Big Jake (Aug 11, 2019)

XBe02Drvr said:


> Also the T34 and the Be1900 (after the useless, treacherous, maintenance nightmare OEM pneumatic nosewheel steering was consigned to the dustbin where it belonged). The Be99 had direct linkage steering off the rudder pedals, lightplane style, but you could easily overpower it with differential thrust. This can be useful if you find yourself on a slick surface with nil braking action, as sometimes happens when you're flying freight into the back country on the back side of the clock. Beta thrust is a lifesaver.
> Cheers,
> Wes



And the B-25 does not have Beta


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## wuzak (Aug 11, 2019)

Big Jake said:


> Installation of the turbo fell under the subject of overall aircraft general arrangement and had to do with allocation of space and overall systems arrangement. Different designers adopted different solutions. Some installed the turbo right behind the engine (P-37), some on top of the tail boom (P-38) and some in the tail (P-47). In the B-17 they are behind the engines, in the B-29 on the side.



The turbo on the XP-37 and YP-37 was below the engine, not behind it.

The B-17's turbos were located in the nacelle. It was similar to the P-38 arrangement, except that they were underneath, not on top.

The B-29's turbos are on the sides of the nacelles, not on the sides of the engine.


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## Shortround6 (Aug 12, 2019)

Zipper730 said:


> So you think they miscalculated, or in some way, got careless?
> 
> Did they miscalculate how much the shaft and gears could take, or did they get careless?.



Maybe they never intended the shaft/gears to handle such a load. The Allison was a lot of years in development and fuel (and thus the ability to even use high boost) change considerably in ten years. 

In 1935 when Howard Hughes set the world speed record using 100 octane fuel (not 100/30) it cost ten times per gallon what 87 octane fuel did. People knew higher octane fuels were coming but they didn't know when or how widespread they would be ( a few planes had small tanks holing 87 octane for take-off and large tanks for 80 octane for cruise).
Building an engine in 1935-37 that a supercharger, drive shaft and gears sized to handle 200hp or more hp would have meant a heavier engine that needed for the existing fuels, or even the fuels in the immediate future.


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## Zipper730 (Aug 12, 2019)

wuzak said:


> I doubt it. Firstly because a single B-series turbo was sufficient for the V-1710 and, secondly, the exhaust and turbo installation wasn't in their scope, instead falling to the airframe manufacturer.


Understood. What made the B-series the B-series, and so on?

Also, I was curious if the engine guys coordinated with the aircraft industry?



Big Jake said:


> Installation of the turbo fell under the subject of overall aircraft general arrangement and had to do with allocation of space and overall systems arrangement. Different designers adopted different solutions. Some installed the turbo right behind the engine (P-37), some on top of the tail boom (P-38) and some in the tail (P-47). In the B-17 they are behind the engines, in the B-29 on the side.


Fascinating. It does appear to have a double wheel on either side with covering that also seems to serve to turn the exhaust rearwards.



Shortround6 said:


> Maybe they never intended the shaft/gears to handle such a load.


It's still kind of strange when you consider that they understood that greater loads were going to be produced by upping the gear-ratio. The only solution is to strengthen things, it appears.


> The Allison was a lot of years in development and fuel (and thus the ability to even use high boost) change considerably in ten years.


So the higher boost ratings put more load on the engine as it was?


> Building an engine in 1935-37 that a supercharger, drive shaft and gears sized to handle 200hp or more hp would have meant a heavier engine that needed for the existing fuels, or even the fuels in the immediate future.


When was the V-1710-59 conceived?


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## wuzak (Aug 13, 2019)

Zipper730 said:


> Understood. What made the B-series the B-series, and so on?



The size.

The B-series was rated for 1,000hp to 1,500hp engines, IIRC.




Zipper730 said:


> Also, I was curious if the engine guys coordinated with the aircraft industry?



What makes you think they didn't?




Zipper730 said:


> Fascinating. It does appear to have a double wheel on either side with covering that also seems to serve to turn the exhaust rearwards.



Which aircraft are you talking about?




Zipper730 said:


> It's still kind of strange when you consider that they understood that greater loads were going to be produced by upping the gear-ratio. The only solution is to strengthen things, it appears.



They were constrained by the wheel case designed for the earlier gear set. If they could get away with gears that could fit inside the existing casing then they would save some time.

But they couldn't and it didn't save time.




Zipper730 said:


> When was the V-1710-59 conceived?



April 1, 1941, 10.37am. 

Seriously, the engine was evolving, as were the aircraft using it.

Problems with the turbo development led to calls for altitude rated engines, which Allison provided. Then, obviously, the engine was lacking altitude performance so they worked towards a solution.

Plus the AAC/F were beating them with the Merlin stick.


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## Zipper730 (Aug 13, 2019)

wuzak said:


> The size. The B-series was rated for 1,000hp to 1,500hp engines, IIRC.


Okay, I thought there was some characteristic about the supercharger layout that made it unique.


> What makes you think they didn't?


That's a good enough answer. I was just curious the degree of coordination.


> Which aircraft are you talking about?


B-29


> They were constrained by the wheel case designed for the earlier gear set. If they could get away with gears that could fit inside the existing casing then they would save some time.


So, they did it under the wishful thinking that they would be able to make it all work and not have to redesign the wheel-case?


> Seriously, the engine was evolving, as were the aircraft using it.


I was kind of wondering whether the idea started in 1938, 1940, 1941, etc.


> Problems with the turbo development led to calls for altitude rated engines, which Allison provided. Then, obviously, the engine was lacking altitude performance so they worked towards a solution.


Makes sense


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## P-39 Expert (Aug 13, 2019)

XBe02Drvr said:


> Hey it's a P39J (J for jet boosted)! They stole one of the XP59's engines to make a V1 killer out of a 'cobra!


Yes that jet engine was it's Achilles heel tending to catch the tail on fire.

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## Glider (Aug 13, 2019)

Personally I like to keep the changes to a small scale. There were a number of aircraft which would have been far more effective with little changes. 
Macchi 202 with 2 x 20mm in the wing instead of 2 x LMG which were hardly worth the effort. 
The P51B with the 6 x HMG or even 4 x 20mm that were given to some of the P51A. 
Me109F with a couple of HMG in the wing which I believe Galland had installed. 
Me109E with drop tanks which I understand were first used in the Spanish Civil War in He51 fighters
The Spitfire with the larger fuel tanks that were in the Mock-up. 

People love talking about this engine/turbo instead of that and often ignore and or forget that these are really heavy and will almost certainly really mess with the COG, weightm wingloading and performance and handling. You don't get something for nothing in aviation


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## gumbyk (Aug 13, 2019)

Glider said:


> Personally I like to keep the changes to a small scale. There were a number of aircraft which would have been far more effective with little changes.
> Macchi 202 with 2 x 20mm in the wing instead of 2 x LMG which were hardly worth the effort.
> The P51B with the 6 x HMG or even 4 x 20mm that were given to some of the P51A.
> Me109F with a couple of HMG in the wing which I believe Galland had installed.
> ...


Not to mention that more power=more fuel burn, more fuel capacity required, and more weight...


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## nuuumannn (Aug 13, 2019)

XBe02Drvr said:


> the Be1900 (after the useless, treacherous, maintenance nightmare OEM pneumatic nosewheel steering was consigned to the dustbin where it belonged).



Slightly off topic, but the Beech 1900 appeared to me to be like a small plane trying to be a big one and not pulling it off very successfully. the company I work for used to operate them and thrashed the living cr*p out of them. Ours were the highest houred B1900s around. I never worked on them except overhaulling their props. Our pilots liked them.

On with the wishful thinking...


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## gumbyk (Aug 13, 2019)

nuuumannn said:


> Slightly off topic, but the Beech 1900 appeared to me to be like a small plane trying to be a big one and not pulling it off very successfully. the company I work for used to operate them and thrashed the living cr*p out of them. Ours were the highest houred B1900s around. I never worked on them except overhaulling their props. Our pilots liked them.
> 
> On with the wishful thinking...


I think that was a combination of an airframe that had been extended to (or beyond) its limits, combined with extremely short routes resulting in higher cycle rates than the manufacturer ever envisaged them doing. I heard that they weren't the highest airframe hours, but certainly fleet leaders in cycles, even though they were the last off the production line


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## nuuumannn (Aug 13, 2019)

gumbyk said:


> I think that was a combination of an airframe that had been extended to (or beyond) its limits,


Clearly. Just look at the extra fins and stuff all over the tail section. I have been told ours were the highest houred aircraft - I'll confirm it when I'm back at work. They certainly were the highest cycles flown.


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## Shortround6 (Aug 13, 2019)

Glider said:


> Macchi 202 with 2 x 20mm in the wing instead of 2 x LMG which were hardly worth the effort.



or even 2 x 12.7mm guns if they couldn't get enough 20mm guns.



Glider said:


> The P51B with the 6 x HMG or even 4 x 20mm that were given to some of the P51A.



One 20mm and one .50 in each wing? 


Glider said:


> Me109F with a couple of HMG in the wing which I believe Galland had installed.



Well unless you can stuff the MG 131s into the cowl you now have 3 different calibers (not really that important) but that means 3 different times of flight and 3 different trajectories, also not really that important but makes a total hash out of the claims for guns on the center line 



Glider said:


> Me109E with drop tanks which I understand were first used in the Spanish Civil War in He51 fighters



The He 51 used them but they had been used by a large number of aircraft 





Curtiss P-6 Hawk used a "slipper" tank? 




Hawk III/BF2C-1





there are others.


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## Glider (Aug 13, 2019)

Shortround6 said:


> or even 2 x 12.7mm guns if they couldn't get enough 20mm guns.
> 
> 
> 
> ...


All excellent points


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## XBe02Drvr (Aug 14, 2019)

nuuumannn said:


> the Beech 1900 appeared to me to be like a small plane trying to be a big one


Exactly. It was a King Air 200 that OD'd on steroids and fell over the 12,500 pound dividing line that separated small aircraft from transport category. It wasn't alone. Metroliners, Banderantes, CASAs, and Jetstreams were also nibbling at that barrier, so the FAA, in its infinite wisdom, created a new "temporary" in-between category called SFAR 41C, which incorporated almost all of the safety and survivability equipment required in transport category, but not the complicated and heavy triple structural redundancies of the big boys.
This was a boon to the commuter airline industry, allowing a generation of economical small airframes to keep growing without being forced to make the high stakes jump to full-on transport category aircraft.
We (Brockway Air) were the launch customer for the 1900C, and operated the airliner version prototype, UB1, N6667L. The actual Type Certificate prototype, UA1, was configured as a corporate executive luxury transport.
We certainly thrashed the p*ss out of ours, each airframe typically flying two aircrew shifts of 8-14 legs each per day, and overnighting in 2-4 outstations consecutively before overnighting at a maintenance base. Fortunately the bird had a very generous MEL due to system redundancy that allowed us to keep operating with lots of gripes in the logbook.
Maintenance wise, the 1900 ate engine mount donuts (cheap) and air cycle air conditioning machines (ouch). We were approved to do hot sections and propeller work in house, instead of having to ship them out as many operators had to.
But despite all the advantages of apparent economy, we had the highest occupied seat mile operating cost in the industry except the Concorde, largely due to our very short legs, our thin (spelled "EAS")* market, and our intense operational pace. Metroliner and Jetstream operators were close behind us.
Apologies for the digression. This is my home turf.
Cheers,
Wes
*EAS = Essential Air Service, government subsidized service to back country communities that had no other passenger common carrier service. Places even Greyhound wouldn't touch for love nor money.

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## P-39 Expert (Aug 14, 2019)

Glider said:


> Personally I like to keep the changes to a small scale. There were a number of aircraft which would have been far more effective with little changes.
> Macchi 202 with 2 x 20mm in the wing instead of 2 x LMG which were hardly worth the effort.
> The P51B with the 6 x HMG or even 4 x 20mm that were given to some of the P51A.
> Me109F with a couple of HMG in the wing which I believe Galland had installed.
> ...


You mean like deleting the wing guns and nose armor from the P-39?


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## nuuumannn (Aug 14, 2019)

XBe02Drvr said:


> This is my home turf.



All good mate, mine too, although not on the Ugly.

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## Elmas (Aug 14, 2019)

P-39 Expert said:


> You mean like deleting the wing guns and nose armor from the P-39?



What about the CG without the nose armor, in a plane whose CG was dangerously aft from the start?


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## XBe02Drvr (Aug 14, 2019)

Elmas said:


> What about the CG without the nose armor, in a plane whose CG was dangerously aft from the start?


We've been honking that horn at him for months now. I wonder if he's tone deaf and can't hear it?
Cheers,
Wes


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## P-39 Expert (Aug 14, 2019)

As I have been saying for months now, move the radios up from the tail cone to behind the pilot above the engine compartment.


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## Milosh (Aug 14, 2019)

Radios tended to be as far as possible from engines due to electrical interference generated by the engine.


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## tyrodtom (Aug 14, 2019)

P-39 Expert said:


> As I have been saying for months now, move the radios up from the tail cone to behind the pilot above the engine compartment.


Radios and engines were separated as much as possible in that era for a good reason, heat, vibration, static from the ignition, made for short radio life and/or bad reception

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## P-39 Expert (Aug 14, 2019)

Many photos of P-39s show some or all of the radios under the rear canopy above the engine.


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## tyrodtom (Aug 14, 2019)

P-39 Expert said:


> Many photos of P-39s show some or all of the radios under the rear canopy above the engine.


Then why did you suggest that they move it to where, according to you, it already was ?
I have one cutaway drawing of a P-39, it shows the radio just forward of the horizontal stabilizer .


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## P-39 Expert (Aug 14, 2019)

Yes and if you remove weight from the nose you should move the radios up to near the center of gravity to restore balance.

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## tyrodtom (Aug 14, 2019)

I think what you think you see in photos, and think is a radio isn't what you think. 
In the cutaway drawings the radio appears larger than the area in the canopy behind the pilot.

So even if it could fit, it would for sure completely block any view toward the rear.
So go to the trouble of designing a almost 360 view canopy, then put something behind the pilot that blocks most of his rear view.
I don't think Bell's engineers were that dumb. 
Or are you tone deaf to that too ?

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## P-39 Expert (Aug 14, 2019)

Thanks for the insult. It blocks a little of the rear view but not all. Many P-39s already had the radios above the engine so it obviously worked.


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## tyrodtom (Aug 14, 2019)

Could you post some of those pictures ?


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## tyrodtom (Aug 14, 2019)

I looked at some P39 schematics .
In some they had both the radio receiver, and the transmitter in the rear compartment.
In a few they had the transmitter still in the rear compartment, but the receiver behind the pilot.

The receiver is about 1/.2 to 1/3 the size of the transmitter.

There's no room for it all behind the pilot, and if you somehow found a way to squeeze it all in, it'd make that 360 view canopy useless.

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## Glider (Aug 14, 2019)

P-39 Expert said:


> You mean like deleting the wing guns and nose armor from the P-39?


The LMG's in the wing wouldn't have helped much so take them out. However as a personal opinion, the version with the 0.5 in the wing was helpful. 
Taking away the nose armour significantly increases the vulnerability of the P39 when attacking bombers, and removing any wing 0.5 makes the P39 far less likely to shoot down the bomber but if that's your choice, feel free.


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## tyrodtom (Aug 14, 2019)

I noticed the only P-39s I found with the radio behind the pilot's headrest seemed to be Russian P-39s, but didn't check enough pictures to be sure.

I've read some Russian tanks early in the war had receivers only, only company, or platoon CO's had transmitters.
Either they did that because their industry couldn't produce enough transmitters, or it wasn't considered important for the line tanks to be able to talk back, they only needed to hear orders and obey, The CO didn't need advice from them.

Surely the Soviets didn't extend that attitude to aviation too.

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## Glider (Aug 14, 2019)

tyrodtom said:


> I noticed the only P-39s I found with the radio behind the pilot's headrest seemed to be Russian P-39s, but didn't check enough pictures to be sure.
> 
> I've read some Russian tanks early in the war had receivers only, only company, or platoon CO's had transmitters.
> Either they did that because their industry couldn't produce enough transmitters, or it wasn't considered important for the line tanks to be able to talk back, they only needed to hear orders and obey, The CO didn't need advice from them.
> ...


Some Russian tanks, in fact most had no radios at the start of the war and relied on flag signals


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## gumbyk (Aug 14, 2019)

tyrodtom said:


> I've read some Russian tanks early in the war had receivers only, only company, or platoon CO's had transmitters.
> Either they did that because their industry couldn't produce enough transmitters, or it wasn't considered important for the line tanks to be able to talk back, they only needed to hear orders and obey, The CO didn't need advice from them.
> 
> Surely the Soviets didn't extend that attitude to aviation too.



Yes, that was exactly their attitude - follow orders, you don't need to be able to talk back.


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## tyrodtom (Aug 14, 2019)

gumbyk said:


> Yes, that was exactly their attitude - follow orders, you don't need to be able to talk back.


 Come to think of it, that's kind of the attitude in any military organization.


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## swampyankee (Aug 14, 2019)

tyrodtom said:


> I noticed the only P-39s I found with the radio behind the pilot's headrest seemed to be Russian P-39s, but didn't check enough pictures to be sure.
> 
> I've read some Russian tanks early in the war had receivers only, only company, or platoon CO's had transmitters.
> Either they did that because their industry couldn't produce enough transmitters, or it wasn't considered important for the line tanks to be able to talk back, they only needed to hear orders and obey, The CO didn't need advice from them.
> ...


I think in the tank case, it was production and cost issues — I believe the Soviets were not unique in not having universal radios


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## Shortround6 (Aug 14, 2019)

We have been over this a few times (at least).

US P-39s used several different radio sets. Pictures of them are in other threads. 
US P-39s, the later ones anyway got IFF receivers and transmitters in addition to the regular communication radios. 

Due to the P-39s less than generous tolerance for weight placement and CG not all of the radio gear could go in the tail cone, and some wound up behind the pilot over the top of the engine. The IFF gear got a demolition charge to prevent it from falling into enemy hands. 

What the Russians got for radios from the US in their P-39s may not have been the most up to date sets. 

One set up used multiple single channel transmitters and multiple single channel receivers ( 4 of one and 3 of the other) and the pilots selector switch in the cockpit selected which units were connected to the mike and earphones. Rapid channel changing was not a feature as it sometimes took over a minute for the newly selected transmitter or receiver to warm up and operate properly. 
I am not sure what modern restorations are doing. At least one in a Museum has this multiple radio installation over the engine (now in Russian Museum?) 
P-39s that fly more than likely have modern radio stuffed into them somewhere (depending on a nearly 80 year old vacuum tube radio doesn't seem to be the smartest thing to do) 

Even the newer, better radios in the later P-39s had at least three pieces. the small switch box in cockpit, the transmitter/receiver proper, and the dynomotor that turned the aircrafts 24/28 volt electricity into 600 volts (or so) for some of the radio circuits. 

I have no idea if the Russians moved the communications radios into the area the IFF used to occupy or what was going on. Or if they moved the complete radio or left the dynomotor (30-40lbs?) where it was and just moved the boxes with the circuits.

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## XBe02Drvr (Aug 14, 2019)

tyrodtom said:


> it wasn't considered important for the line tanks to be able to talk back, they only needed to hear orders and obey, The CO didn't need advice from them.
> Surely the Soviets didn't extend that attitude to aviation too.


Why not? It fits their ideology to a "T".


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## Kevin J (Aug 14, 2019)

tyrodtom said:


> I noticed the only P-39s I found with the radio behind the pilot's headrest seemed to be Russian P-39s, but didn't check enough pictures to be sure.
> 
> I've read some Russian tanks early in the war had receivers only, only company, or platoon CO's had transmitters.
> Either they did that because their industry couldn't produce enough transmitters, or it wasn't considered important for the line tanks to be able to talk back, they only needed to hear orders and obey, The CO didn't need advice from them.
> ...



On their early planes, yes.


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## Shortround6 (Aug 14, 2019)

Kevin J said:


> On their early planes, yes.


In 1941 some batches of Yak-1s only had one radio in ten aircraft.


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## Elmas (Aug 15, 2019)

The radios for Red Army tanks were U.S. production on the Lend-Lease basis.
My Father, that was a Radio Amateur, had in early '70 a surplus transceiver, working around 30 Mhz, that had both indications on the knobs, in English and Cyrillic, probably coming from the remains of a supply never sent to Soviet Russia, and stored in a big place near Livorno, where all the remnants of the unwanted equipment left behind by the Allied Armies were stored and sold.
No doubt about the American design and cosnstruction of that radio, very similar to this one, if not the same



So, the lack of radios of the Red Army tanks in the early stage of the war was not only a simple matter of ideology, I think.

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## P-39 Expert (Aug 15, 2019)

P=39s were the first Russian planes to have radios in all planes. The Germans could pick off Russian planes one by one with no way to warn others in the squadron.


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## Shortround6 (Aug 15, 2019)

Russian (or communist?) ideology/military theory was a lot more advanced than some people give it credit for. 
Russian inventiveness and/or technical theory was also more advanced than they are often given credit for.

Actual Russian capability to mass produce weapons to fit the military theory and technical designs was way below what the Russians wanted. 






Russian tanks supplied to the Chinese with radios (at least the ones nearest the camera).

The Russians simply did not have a radio/electronics industry large enough to supply the needed number of radios regardless of what military doctrine wanted. 
French in 1940 had only about 1/3 or less of their tanks with radios and even the Germans used hundreds of MK I tanks in Poland and France (lesser numbers in Russia) with only radio receivers, not transmitters. 

War time Russian doctrine/ideology often had to be simplified or cut back due to both equipment shortages and lack of training of both troops and officers. Stalin's purges of the late 30s had decimated the Russian officer corp and many officers were operating a number of grades above the level they had the experience and training for (assuming that they would have ever reached those grades in the first place). 

When looking at Russian equipment and how it was used we have to be careful not to confuse or misinterpreted cause and effect.

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## Glider (Aug 15, 2019)

P-39 Expert said:


> P=39s were the first Russian planes to have radios in all planes. The Germans could pick off Russian planes one by one with no way to warn others in the squadron.


I strongly believe that the Hurricane was the first by some margin

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## Kevin J (Aug 15, 2019)

Elmas said:


> The radios for Red Army tanks were U.S. production on the Lend-Lease basis.
> My Father, that was a Radio Amateur, had in early '70 a surplus transceiver, working around 30 Mhz, that had both indications on the knobs, in English and Cyrillic, probably coming from the remains of a supply never sent to Soviet Russia, and stored in a big place near Livorno, where all the remnants of the equipment left by the Allied Armies were stored and sold.
> No doubt about the American design and cosnstruction of that radio, tubes were, for example, 12BY7 and so on.
> So, the lack of radios in the Red Army tanks in the early stage of the was not only a simple matter of ideollogy, I think.





Glider said:


> I strongly believe that the Hurricane was the first by some margin


Some early Russian fighters had radios but they were crap.


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## ThomasP (Aug 19, 2019)

(re armoured vehicle radio doctrine)

As far as I am aware, only the UK had 2-way radios in nearly all their tanks at the start of WWII. At the beginning the UK had 3 different radios in operational tank units, the No.7 (short range), No.9(medium range) , and No.11(very short to short range). Cruiser and Infantry line tanks usually had both No.9 and No.11 radios, with company HQ tanks having a second No.11 radio for communication over the command and artillery nets. The Light Tanks MkV&VI were fitted with only 1 radio, either No.7 or No.11, primarily due to lack of space.

The No.19 set (very-short to short range, plus medium range) began replacing the No.9 and No.11 sets in 1941.


The French intended to fit all of their armored division tanks, along with their cavalry/scout units, with 2-way radios but the war intervened.


Although all US line tanks in US service came with radios, only the command vehicles (i.e. platoon, company, battalion, regiment command) and specialist vehicles (ie OP) had 2-way radios. The regular line tanks only had receiver sets. This was true through the end of the war as far as I have been able to determine.

US line tanks had only a SCR-538 (1x BC-603 receiver), except for platoon command tanks which had a SCR-528 (1x BC604 transmitter + 1x BC603 receiver) set, company command tanks which had a SCR-508 (1x BC604 transmitter + 2x BC603 receivers), and battalion command tanks which had a SCR-508 and a SCR-506 high power long range set.


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## cherry blossom (Aug 27, 2019)

It might have been possible to improve the Kugisho MXY7 Ohka if the Japanese Navy and Army had cooperated, although this would not have benefited either the Ohka's pilots or Japan. Development of the Ohka started in 1943 and the preliminary design was approved in August 1944 as described in "Japanese Special Attack Aircraft & Flying Bombs" by Ryusuke Ishiguro & Tadeusz Januszewski, page 149). This states "Initially it was planned to use a liquid fuel rocket that would give it a long range, but..." and goes on to explain that Japanese industry could not produce the rocket fuels used by Germany for the Me 163. The design team thus chose to use three solid fuel RATO rockets that were already in production for the Navy and gave a total of 800 kg thrust, although they were fired sequentially to extend the range with each giving 8-10 seconds of thrust. 

The consequence was that the G4M carriers had to approach as close as 35 km from the American Fleet which caused them to suffer interception by radar directed fighters, often before launching their Ohkas.

I recently bought "Japanese Aero-Engines 1910-1945" by Mike Goodwin & Peter Starkings, which mentioned the Kayaba Model 1 ramjet (pages 192-3), which suggests that two examples had been built and tested for the Japanese Army in 1943 before the design of the Kayaba Katsuodori fighter was commenced. Power was quoted as 300 to 750 kg of thrust at speeds of 230 to 685 mph. The design was never flown but https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=1461 gives an empty weight of only 1,874 lb (850 kg) for the fighter and a MTOW of 6,614 lb (3,000 kg), for 30 minutes of operation.

The design was only a paper proposal Kayaba Katsoudori as it was rejected by the Army, who preferred a design based on the Me 163. However, Kayaba had been working on ramjets since 1937 and it seems plausible that they had a working ramjet. The army may have doubted their ability to design an aircraft as the Wikipedia article Kayaba Ku-4 - Wikipedia on their previous project, the Ku-4 glider has "Work on the prototype was well advanced by April 1941, but the following month, Kimura's relationship with the Army soured following the crash of the Ku-2. The Ku-4 was cancelled, and Kimura eventually received only ¥17,000 of the ¥200,000 that had been promised for the development of his tailless designs." 

Returning to the Ohka, it was normally released at a speed of around 280-325 Km/h and between 6,000 and 8,250m and glided towards the target at a glide angle of 5 degrees. The rockets could accelerate the Ohka to 860 km/h before entering a final 50 degree dive at up to 995 km/h (Isiguro & Tadeusz, page 159). The glider version reached 462 km/h in an unpowered dive, suggesting that it would be easy to reach sufficient speed to use a ramjet after launch. 

Thus I propose an Ohka powered by the Kayaba Model 1 ramjet and suspect that it would have sufficient range to be launched well before interception of the carrier.


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## XBe02Drvr (Aug 27, 2019)

cherry blossom said:


> Thus I propose an Ohka powered by the Kayaba Model 1 ramjet and suspect that it would have sufficient range to be launched well before interception of the carrier.


The first standoff AGM missile. "A missile with a man in it"! (Any aging cold warriors remember that phrase?)
Cheers,
Wes

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## davparlr (Aug 27, 2019)

delete


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## davparlr (Aug 27, 2019)

Shortround6 said:


> Curtiss P-6 Hawk used a "slipper" tank?
> View attachment 548813
> 
> Hawk III/BF2C-1


In my opinion, the P-6 Hawk is the most beautiful bi-plane ever built, especially with that paint scheme.

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## swampyankee (Aug 27, 2019)

XBe02Drvr said:


> The first standoff AGM missile. "A missile with a man in it"! (Any aging cold warriors remember that phrase?)
> Cheers,
> Wes



Yep; remember that phrase. Usually (or at least, hopefully) it was not to be taken literally in the 1950s

The Okha was a guided missile, the logical ancestor of all the air-launched anti-ship missiles. Alas, the "missile with a man in it" was being taken quite literally.

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## Zipper730 (Oct 11, 2019)

I'm curious if a similar version of this thread could be placed in the Cold-War Era?


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## pinsog (Oct 11, 2019)

XBe02Drvr said:


> The first standoff AGM missile. "A missile with a man in it"! (Any aging cold warriors remember that phrase?)
> Cheers,
> Wes


I thought “missile with a man in it” was the 104 Starfighter nick name?


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## XBe02Drvr (Oct 12, 2019)

pinsog said:


> I thought “missile with a man in it” was the 104 Starfighter nick name?


BINGO! In the zero launch version, an SA2 with an "organic" guidance system.

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## Zipper730 (Dec 31, 2019)

Regarding the following

*Shortnose P-37*
I was thinking that the stuff that 
W
 wuzak
had proposed including repositioning the radiator within the wing, the intercooler under the engine, as well as the following...

Radiator & oil-cooler repositioned to wings
Intercooler positioned under the engine
Auxiliary fuel tank positioned behind/below pilot
Radio transmitter & receiver positioned aft of the pilot
Battery repositioned aft of the pilot
Hydraulic tank & pump repositioned aft of cockpit
... I think it's a good idea.

As for taking some design influence from the P-53/P-60, it seems that the XP-60A would be the best configuration to use, as it seemed that Curtiss couldn't quite get the belly-radiator design.

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## PAT303 (Dec 31, 2019)

cherry blossom said:


> Returning to the Ohka, it was normally released at a speed of around 280-325 Km/h and between 6,000 and 8,250m and glided towards the target at a glide angle of 5 degrees. The rockets could accelerate the Ohka to 860 km/h before entering a final 50 degree dive at up to 995 km/h (Isiguro & Tadeusz, page 159). The glider version reached 462 km/h in an unpowered dive, suggesting that it would be easy to reach sufficient speed to use a ramjet after launch.



Interestingly I have been giving the Okha some thought lately for some reason, why not fit it with a tractor Sakae?, it would outrun everything in the air and with say 50G of fuel have a range of over 100 miles.


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## Admiral Beez (Dec 31, 2019)

wuzak said:


> This is loking a lot like an earlier thread
> 
> This is the way it should have been from the beginning....


Ha. As soon as I read the above my first thought was I bet the authors of this post and the “earlier thread” are the same.


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## tyrodtom (Dec 31, 2019)

PAT303 said:


> Interestingly I have been giving the Okha some thought lately for some reason, why not fit it with a tractor Sakae?, it would outrun everything in the air and with say 50G of fuel have a range of over 100 miles.



What would be the point of a Okha with a engine where the war head had been ?
No warhead, no big boom.
A fuselage designed to be pushed from the back, with just a heavy load on the front would take a little redesigning to withstand being pulled and torqued from the front. Then you'd need to add some kind of method of carrying a external bomb.

The biggest flaw of the Ohka was it's need to be carried by a mother aircraft. 
A Okha with a propeller assist would greatly extend the launch range, but not get rid of the need for a mother aircraft.
The need to provide clearance for the propeller of the Ohka would mean the Okha would hang down even more on the mother aircraft.
I wonder if anything in the Japanese inventory had the ground clearance to carry such tall device under it ?


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## MiTasol (Jan 1, 2020)

One model of the Okha did have a propeller assist.

The _Ohka_ _Model 22_ was powered by a four cylinder in line engine driving a ducted fan and did not need additional clearance. Smithsonian have one, see Kugisho MXY7 Ohka (Cherry Blossom) 22. Unfortunately none of the ten photos show the engine




For more detail see Francillion's _Japanese aircraft of the second world war



_

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## P-39 Expert (Jan 1, 2020)

MiTasol said:


> One model of the Okha did have a propeller assist.
> 
> The _Ohka_ _Model 22_ was powered by a four cylinder in line engine driving a ducted fan and did not need additional clearance. Smithsonian have one, see Kugisho MXY7 Ohka (Cherry Blossom) 22. Unfortunately none of the ten photos show the engine
> View attachment 565589
> ...


I believe the piston engine was used to compress the intake air for the Ohka's jet engine, not actually needing a propeller.


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## Ivan1GFP (Jan 1, 2020)

P-39 Expert said:


> I believe the piston engine was used to compress the intake air for the Ohka's jet engine, not actually needing a propeller.



That sounds about right if this is the one at NASM Udvar Hazy. That model of the Ohka has a couple side intakes but doesn't have a propeller. We took a guest from Japan to visit the museum and this was the display that seemed to attract the most attention.


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## tyrodtom (Jan 1, 2020)

MiTasol said:


> One model of the Okha did have a propeller assist.
> 
> The _Ohka_ _Model 22_ was powered by a four cylinder in line engine driving a ducted fan and did not need additional clearance. Smithsonian have one, see Kugisho MXY7 Ohka (Cherry Blossom) 22. Unfortunately none of the ten photos show the engine
> View attachment 565589
> ...



It says it was never operational. 
Did it ever fly at all, ? or was it just a proposal with a mock-up?


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## GrauGeist (Jan 1, 2020)

The model 22 was never used in combat and several were recovered after the war. There's one at the Smithsonian.


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## MiTasol (Jan 1, 2020)

tyrodtom said:


> It says it was never operational.
> Did it ever fly at all, ? or was it just a proposal with a mock-up?



Fifty were completed and full scale production was planned but never achieved.
On the material available to Francillion in the late sixties it flew only only once. I doubt that any other flights have been found in other records since


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## MiTasol (Jan 1, 2020)

Ivan1GFP said:


> That sounds about right if this is the one at NASM Udvar Hazy. That model of the Ohka has a couple side intakes but doesn't have a propeller. We took a guest from Japan to visit the museum and this was the display that seemed to attract the most attention.



In place of the propeller it has a single stage "axial compressor" (in other words a ducted/shrouded fan - which is in turn a propeller with many blades) with what is basically an afterburner behind the compressor. There is a little more detail at Air Technical Arsenal Tsu-11 Campini-type engine and interestingly this claims only three engines were built though with 50 aircraft *delivered *and others partially built this seems open to question. Maybe only three were shipped to the US. I will check the records I know of. *EDiT *_Data on Japanese aircraft shipped to United States for study purposes. Report No. 15c_ does not even list this aircraft, let alone any engines

There are a number of photos of the engine at https://www.enginehistory.org/Piston/Japanese/japanese.shtml and interestingly the engine had port type fuel injection and obtained its air supply from behind the fan thus ensuring a small level of supercharging. There is no indication of how the engine was cooled as the compressor air all bypasses the engine. There are no photos of the compressor

My web search shows there is a webpage https://everything.explained.today/Tsu-11/ but my browser says it is not available.

There is a wiki page at Ishikawajima Tsu-11 - Wikipedia and further detail in the page Hitachi Hatsukaze - Wikipedia


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## MiTasol (Jan 1, 2020)

From











Unfortunately I do not have the diagrams.
Note that the 110hp engine is now 150hp so that small amount of supercharging had a major effect if this report is correct. And the weight of 1lb/lb thrust is very high.
Note also that, like Smithsonian, they say only 3 engines were built.


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## PAT303 (Jan 1, 2020)

tyrodtom said:


> What would be the point of a Okha with a engine where the war head had been ?
> No warhead, no big boom.
> A fuselage designed to be pushed from the back, with just a heavy load on the front would take a little redesigning to withstand being pulled and torqued from the front. Then you'd need to add some kind of method of carrying a external bomb



Sorry I had a blonde moment, a pusher Sakae instead of the rockets.


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## MiTasol (Jan 1, 2020)

More on the Tsu-11 including a photo of the compressor and some interesting history challenging the _only 3 built _narrative.
http://www.enginehistory.org/Piston/Japanese/Mawhinney/nasm_research_3.shtml


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## P-39 Expert (Jan 1, 2020)

Zipper730 said:


> Regarding the following
> 
> *Shortnose P-37*
> I was thinking that the stuff that
> ...


Always thought the P-40 radiator arrangement was very good. Virtually all the radiators and ducting were "hidden" in the area below the engine and ahead of the wing, only adding a very small amount of space to the frontal area. I think that even this could have been reduced by substituting rectangular coolant and oil radiators, or ones similar to those used on the P-40F. Altogether a very neat and compact arrangement. P-40 was one of the few US fighters that met cooling requirements during tests.

Biggest problem with the P-40 was excessive weight.


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## Admiral Beez (Jan 2, 2020)

Westland Whirlwind. 

Belt magazines feeding from behind and under pilot to nose.
Fuel sharing valve between sides and engines.
Two stage supercharger on Peregrines for both low and high altitude performance. No, not Merlins, if we go that route we might as well make a Welkin.
Larger or different flaps for shorter and slower takeoff and landings.
More internal fuel for increased endurance. Consider underwing or chin radiators to free up wing roots for fuel.


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## Kevin J (Jan 2, 2020)

Admiral Beez said:


> Westland Whirlwind.
> 
> Belt magazines feeding from behind and under pilot to nose.
> Fuel sharing valve between sides and engines.
> ...


Chin radiators were tested out by Rolls-Royce, IIRC, top speed at sea level on 100 octane went up from 338 mph to 362 mph. Details are on another forum, you'd have to do a search for it. So theoretically, you could easily add more fuel. I think we've gone through the Whirlwind development issues in another thread. The problems with the Whirlwind are twin engine complexity, low diving speed and lack of a suitable engine, then there's cost; why buy the Whirlwind when you can a Warhawk or Mustang for half the price that does the job as well as or better.


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## wuzak (Jan 2, 2020)

Kevin J said:


> Chin radiators were tested out by Rolls-Royce, IIRC, top speed at sea level on 100 octane went up from 338 mph to 362 mph. Details are on another forum, you'd have to do a search for it. So theoretically, you could easily add more fuel. I think we've gone through the Whirlwind development issues in another thread. The problems with the Whirlwind are twin engine complexity, low diving speed and lack of a suitable engine, then there's cost; why buy the Whirlwind when you can a Warhawk or Mustang for half the price that does the job as well as or better.




I would like to see that mate. 

But since I have no idea where to look, perhaps you could find it for us.


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## Kevin J (Jan 2, 2020)

wuzak said:


> I would like to see that mate.
> 
> But since I have no idea where to look, perhaps you could find it for us.


Here's the photo that I saved to my laptop. I'll have a look for the forum next.

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## Kevin J (Jan 2, 2020)

Kevin J said:


> Here's the photo that I saved to my laptop. I'll have a look for the forum next.
> View attachment 565633


IIRC a Spitfire I with 100 octane and 16 lbs boost did 328 mph at sea level, the Rolls-Royce experimental Whirlwind with the same, 338 mph and with the chin radiators 362 mph which you may or may not agree is plausible. So theoretically, you should get about 385 mph out of it at 15,000 feet similar to an early Typhoon I, but that's it, above that the speed falls off. Max dive speed is also very low at about 400 mph similar to the Beaufighter. The Whirlwind is a day fighter only, not all weather so you can't get a lot of use out of it. You're better off with Beaufighters and Typhoons, and of course Mosquitoes when they eventually enter service in large numbers. Sorry, but I can't find the forum with more detailed stats, all I have is this one saved.
https://bbs.hitechcreations.com/smf/index.php/topic,313538.120.html


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## P-39 Expert (Jan 2, 2020)

Admiral Beez said:


> Westland Whirlwind.
> 
> Belt magazines feeding from behind and under pilot to nose.
> Fuel sharing valve between sides and engines.
> ...


The belt feed for the 20mm cannons was a further development that would have come if Whirlwind had stayed in production. Drums held 60 rounds, about half what was needed.


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## wuzak (Jan 2, 2020)

Kevin J said:


> IIRC a Spitfire I with 100 octane and 16 lbs boost did 328 mph at sea level, the Rolls-Royce experimental Whirlwind with the same, 338 mph and with the chin radiators 362 mph which you may or may not agree is plausible. So theoretically, you should get about 385 mph out of it at 15,000 feet similar to an early Typhoon I, but that's it, above that the speed falls off. Max dive speed is also very low at about 400 mph similar to the Beaufighter. The Whirlwind is a day fighter only, not all weather so you can't get a lot of use out of it. You're better off with Beaufighters and Typhoons, and of course Mosquitoes when they eventually enter service in large numbers. Sorry, but I can't find the forum with more detailed stats, all I have is this one saved.
> https://bbs.hitechcreations.com/smf/index.php/topic,313538.120.html



338mph to 362mph suggests a reduction in drag of 19%.

I call BS.

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## Kevin J (Jan 2, 2020)

P-39 Expert said:


> The belt feed for the 20mm cannons was a further development that would have come if Whirlwind had stayed in production. Drums held 60 rounds, about half what was needed.


The Whirlwind is a niche long range day fighter and expensive too. It has no development potential.


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## Kevin J (Jan 2, 2020)

Kevin J said:


> The Whirlwind is a niche long range day fighter and expensive too. It has no development potential.


The Seafire LIII went up from 341 mph to 358 mph with drag saving measures. So it's feasible.


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## Snautzer01 (Jan 2, 2020)

pinsog said:


> I thought “missile with a man in it” was the 104 Starfighter nick name?


Funilly enough the Germans called it "erdnagel" meaning ground peg.

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## Shortround6 (Jan 2, 2020)

wuzak said:


> 338mph to 362mph suggests a reduction in drag of 19%.
> 
> I call BS.


For this to be true the Westland wing leading edge radiators must have been the world's worst. We have other threads with people wanting to yank off chin radiators and replace then with leading edge radiators on other aircraft.
The plane in the picture (photo shopped?) Has ejector exhaust and may pick up some thrust there but one has to believe an awfull lot that such a Whirlwind was faster than a MK XIV Spit using 18lbs of boost.


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## Zipper730 (Jan 2, 2020)

P-39 Expert said:


> Always thought the P-40 radiator arrangement was very good.


I generally agree: The P-40 basically proved to be a good fighter for its time. It's just that the original intent for, what would become the P-40, was the XP-37. So the idea was how to reduce the overlong nose.


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## Kevin J (Jan 2, 2020)

Shortround6 said:


> For this to be true the Westland wing leading edge radiators must have been the world's worst. We have other threads with people wanting to yank off chin radiators and replace then with leading edge radiators on other aircraft.
> The plane in the picture (photo shopped?) Has ejector exhaust and may pick up some thrust there but one has to believe an awfull lot that such a Whirlwind was faster than a MK XIV Spit using 18lbs of boost.


Didn't the Lightning go faster with chin radiators.


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## P-39 Expert (Jan 2, 2020)

Kevin J said:


> Didn't the Lightning go faster with chin radiators.


Yes, but with a lot more HP.


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## Kevin J (Jan 2, 2020)

P-39 Expert said:


> Yes, but with a lot more HP.


The chin radiators enabled it to cool the engines better. The Cobra was faster after the draggy turbo inlets were removed. The Spitfire lost 20 mph productionising it. The Spitfire V could be cleaned up by another 35 mph, but only the Seafire used all these mods.


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## drgondog (Jan 2, 2020)

P-39 Expert said:


> Always thought the P-40 radiator arrangement was very good. Virtually all the radiators and ducting were "hidden" in the area below the engine and ahead of the wing, only adding a very small amount of space to the frontal area. I think that even this could have been reduced by substituting rectangular coolant and oil radiators, or ones similar to those used on the P-40F. Altogether a very neat and compact arrangement. P-40 was one of the few US fighters that met cooling requirements during tests.
> 
> Biggest problem with the P-40 was excessive weight.



Under the engine is the Worst location possible from consideration of profile/parasite drag. The P-39/P-51 were much better. Even the Hurricane and Spit and Bf 109F/G were better as the flow around the nose, cockpit and leading edge of the wing is more fully developed with respect to delayed boundary layer build up.

Weight is a function of internal volume required for various fractions (fuel, armament, crew, etc.) as well as the structural design limit and ultimate load factors - for good design. Otherwise take your pick for crappy design. Remember that the P-40 firewall and aft fuselage design originated from the pre-Allison P-36 and Curtiss never figured out a low drag radiator scheme adequate for climb conditions using Meredith Effect concepts of burying the radiator/oil cooler aft of the mid chord of the wing.

The only relief for crappy design is increased horsepower - and lots of it.

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## wuzak (Jan 2, 2020)

Kevin J said:


> Didn't the Lightning go faster with chin radiators.



The P-38 never had chin radiators.

What the P-38J onwards had were core type intercoolers in place of the leading edge intercoolers on earlier models. The P-38J had the same engine as the P-38H, but could run at higher power because the intercooler was superior and allowed higher boost. The second benefit of the chin intercoolers was that the leading edges were freed up for extra fuel tanks, giving greater range.


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## wuzak (Jan 2, 2020)

Kevin J said:


> The Seafire LIII went up from 341 mph to 358 mph with drag saving measures. So it's feasible.



At what altitudes?

Were they the same engine? Did they have the same power?


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## Reluctant Poster (Jan 2, 2020)

A little off topic but I thought of the 24 Calquin. The radial engined version of the Mosquito built in Argentina.
I.Ae. 24 Calquin - Wikipedia

Not the best example of improving a design.

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## xylstra (Jan 2, 2020)

Zipper730 said:


> It's an intellectual exercise, revolving around how aircraft could have been made better with technology available at the time around either
> 
> The existing specification: Basically, the idea would be working within the existing specification, but you could modify or change anything within the boundary of it.
> A different winner: Sometimes the problem wasn't the design so much as the winner to the contender: While way after WWII, many feel the YF-23 should have won over the YF-22, for example.
> ...


Although yours, and the replies that have followed are entirely focussed on WW2 aircraft design, if you want the perfect example of a truly futuristic and fantastic design, have a look at the 1917 de Bruyere C1 - compare it to say, the RUTAN 'Quickie" from ~65 years later. Truly visionary, and amazing!


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## Admiral Beez (Jan 3, 2020)

One firm that desperately needed some design help was the fighter department of Martin-Baker.

The same country that made the Spitfire made this POS.

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## Elmas (Jan 3, 2020)

Admiral Beez said:


> One firm that desperately needed some design help was the fighter department of Martin-Baker.
> 
> The same country that made the Spitfire made this POS.
> 
> View attachment 565695



And certainly they found the help needed...






Photo source: the Internet

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## Kevin J (Jan 3, 2020)

wuzak said:


> At what altitudes?
> 
> Were they the same engine? Did they have the same power?


Absolutely same engine, same height, its all in wwiiaircraftperformance.org.


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## Kevin J (Jan 3, 2020)

Admiral Beez said:


> One firm that desperately needed some design help was the fighter department of Martin-Baker.
> 
> The same country that made the Spitfire made this POS.
> 
> View attachment 565695


Stick a couple of floats underneath it and we could have had a decent float plane fighter


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## Kevin J (Jan 3, 2020)

They learnt fast, but not fast enough. If only the MB3 had the Griffon. 


Elmas said:


> And certainly they found the help needed...
> 
> View attachment 565697
> 
> ...


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## wuzak (Jan 3, 2020)

Kevin J said:


> Absolutely same engine, same height, its all in wwiiaircraftperformance.org.



Really.

There is only 1 report on the MK.III of that site and two speed charts - for LF.III and F.III which have different FTH.


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## buffnut453 (Jan 3, 2020)

Admiral Beez said:


> One firm that desperately needed some design help was the fighter department of Martin-Baker.
> 
> The same country that made the Spitfire made this POS.
> 
> View attachment 565695



What's so very wrong about the MB2? It offered reasonable performance, an air-cooled engine and was rugged and easy to maintain. Granted, it didn't have the looks of the Spitfire, or even the Hurricane, but I don't think it was that bad as a design. Other manufacturers would have done well to emulate MB's emphasis on ergonomics and ease of maintenance.

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## Kevin J (Jan 3, 2020)

wuzak said:


> Really.
> 
> There is only 1 report on the MK.III of that site and two speed charts - for LF.III and F.III which have different FTH.


The LFIII tops out at 296 knots or about 340 mph,


wuzak said:


> Really.
> 
> There is only 1 report on the MK.III of that site and two speed charts - for LF.III and F.III which have different FTH.


The LIII max speed is 296 knots so 340 mph at 6000 feet, the FIII at 351 mph at 10500 feet. These would be the figures before the general cleanup, like individual exhaust stacks, close attention to badly fitting panels, and on Cunliffe-Owen built Seafires, flush riveting which increased speed on the LIII to 358 mph. If you believe the lower figures then why not use the FM-2 instead?


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## yulzari (Jan 3, 2020)

Kevin J said:


> Here's the photo that I saved to my laptop. I'll have a look for the forum next.
> View attachment 565633


IIRC this was found to be Photoshopped. Enhancement suggests that the leading edge radiators are still in place. I can't find the reference but it was in some modelling forum.

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## yulzari (Jan 3, 2020)

Admiral Beez said:


> One firm that desperately needed some design help was the fighter department of Martin-Baker.
> 
> The same country that made the Spitfire made this POS.
> 
> View attachment 565695


The much lauded MB5 essentially used the same structure. Martin Baker were not allowed a Merlin nor immediate access to retracting undercarriage kit. Easy to make and easy to maintain.


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## P-39 Expert (Jan 3, 2020)

drgondog said:


> Under the engine is the Worst location possible from consideration of profile/parasite drag. The P-39/P-51 were much better. Even the Hurricane and Spit and Bf 109F/G were better as the flow around the nose, cockpit and leading edge of the wing is more fully developed with respect to delayed boundary layer build up.
> 
> Weight is a function of internal volume required for various fractions (fuel, armament, crew, etc.) as well as the structural design limit and ultimate load factors - for good design. Otherwise take your pick for crappy design. Remember that the P-40 firewall and aft fuselage design originated from the pre-Allison P-36 and Curtiss never figured out a low drag radiator scheme adequate for climb conditions using Meredith Effect concepts of burying the radiator/oil cooler aft of the mid chord of the wing.
> 
> The only relief for crappy design is increased horsepower - and lots of it.


Why is the worst location for coolant/oil radiators under the engine?


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## Kevin J (Jan 3, 2020)

yulzari said:


> IIRC this was found to be Photoshopped. Enhancement suggests that the leading edge radiators are still in place. I can't find the reference but it was in some modelling forum.


You could be right, but theoretically the performance is feasible given the way the radiator on the Mustang gave extra thrust and boosted performance.


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## drgondog (Jan 3, 2020)

P-39 Expert said:


> Why is the worst location for coolant/oil radiators under the engine?


Re-read my comment.

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## wuzak (Jan 3, 2020)

Kevin J said:


> You could be right, but theoretically the performance is feasible given the way the radiator on the Mustang gave extra thrust and boosted performance.



The Typhoon Mk I with wing leading edge radiators was significantly faster than the Typhoon Mk V with chin radiator. Albeit with a different spec engine.

The Mosquito was trialed with the Beaufighter/Lancaster engine power egg with the chin radiator, and was found to be no faster, slightly better radiator cooling, but worse oil cooling.

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## Admiral Beez (Jan 3, 2020)

P-39 Expert said:


> Why is the worst location for coolant/oil radiators under the engine?


Surely the worst location for coolant/oil radiators is above the engine. Everyone put them somewhere below the engine.


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## GrauGeist (Jan 3, 2020)

Kevin J said:


> The problems with the Whirlwind are twin engine complexity, low diving speed and lack of a suitable engine, then there's cost; why buy the Whirlwind when you can a Warhawk or Mustang for half the price that does the job as well as or better.


The Whirlwind was being developed at the same time as the P-40 and first flew years before the P-51 was even conceived.


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## Reluctant Poster (Jan 3, 2020)

wuzak said:


> The Typhoon Mk I with wing leading edge radiators was significantly faster than the Typhoon Mk V with chin radiator. Albeit with a different spec engine.
> 
> The Mosquito was trialed with the Beaufighter/Lancaster engine power egg with the chin radiator, and was found to be no faster, slightly better radiator cooling, but worse oil cooling.


I believe Rolls Royce felt the chin radiator was a better solution for the Mosquito. That being said it may have been more difficult to implement with the two stage engines.


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## Reluctant Poster (Jan 3, 2020)

wuzak said:


> Really.
> 
> There is only 1 report on the MK.III of that site and two speed charts - for LF.III and F.III which have different FTH.


The F III used the Merlin 55, the LF III used the Merlin 55M. The difference being that the 55M had a smaller diameter impeller.


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## Admiral Beez (Jan 3, 2020)

Hawker Typhoon. Fix the tail at the onset, get a reliable and mass produced Sabre or Centaurus engine into the Typhoon by end 1940. Send four squadrons to Malaya in early 1941, eight more by October 1941.


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## MiTasol (Jan 3, 2020)

Centaurus production started in 1942 so it would be difficult to _send four squadrons to Malaya in early 1941, eight more by October 1941._

And yes I do know it first ran in 1938 but is was not produced until 1942 because Bristol needed to improve the reliability of their entire sleeve valve engine line and it did not make it into any ww2 aircraft

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## wrenchedmyspanner (Jan 3, 2020)

Snautzer01 said:


> Funilly enough the Germans called it "erdnagel" meaning ground peg.



That sounds a lot like a Lawn Dart (the old, now banned style) to me.


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## Shortround6 (Jan 3, 2020)

Forget the Typhoon. Give Wittle more money in 1930s, get the engine sorted out sooner and get Gloster on the ball. Send 5 squadrons of armed E.28/39s to Malaya in the Spring of 1941 and 10 squadrons more by Oct 1941. Japanese are in for a nasty surprise

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## Kevin J (Jan 3, 2020)

Shortround6 said:


> Forget the Typhoon. Give Wittle more money in 1930s, get the engine sorted out sooner and get Gloster on the ball. Send 5 squadrons of armed E.28/39s to Malaya in the Spring of 1941 and 10 squadrons more by Oct 1941. Japanese are in for a nasty surprise


I like the idea.


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## Admiral Beez (Jan 4, 2020)

MiTasol said:


> Centaurus production started in 1942 so it would be difficult to _send four squadrons to Malaya in early 1941, eight more by October 1941._
> 
> And yes I do know it first ran in 1938 but is was not produced until 1942 because Bristol needed to improve the reliability of their entire sleeve valve engine line and it did not make it into any ww2 aircraft


Hence my opening two sentences.


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## MikeMeech (Jan 4, 2020)

wuzak said:


> The Typhoon Mk I with wing leading edge radiators was significantly faster than the Typhoon Mk V with chin radiator. Albeit with a different spec engine.



Hi

I presume you mean the Tempest as there were only the Typhoon (F18/37 spec. First flight 24 Feb 1940) Mk. Ia (12x.303) and Ib(4x20mm), the Typhoon II became the Tempest (Spec. F10/41) before flying. Tempest V (Sabre II) first flight 2 Sept. 1942, Tempest I (Sabre IV) first flight 24 Feb. 1943, Tempest II (Centaurus IV) first flight 28 Jun. 1943. While the Tempest I was faster there were problems with the Sabre IV so the order for the RAF was changed from Tempest I to Tempest V.
The Centaurus was also tested on the Hawker Tornado aircraft (also spec. F18/37) which was mainly designed for the Vulture engine, this was cancelled. The Tempest took over the Centaurus engine option. Typhoon development was delayed in part by the Battle of Britain and the demands to keep up Hurricane production. I don't think there would have been any possibility of Tempest aircraft before December 1941, whatever scenario is used.

Mike


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## wuzak (Jan 4, 2020)

MikeMeech said:


> Hi
> 
> I presume you mean the Tempest



Yes, I meant the Tempest I and V.


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## Shortround6 (Jan 4, 2020)

Kevin J said:


> then there's cost; why buy the Whirlwind when you can a Warhawk or Mustang for half the price that does the job as well as or better.


Timing, Timing,Timing.

When the Whirlwind was entering production and first entering squadron service the Warhawk and Mustang pretty much existed as drawings on paper and parts being assembled into prototypes.

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## MiTasol (Jan 4, 2020)

Shortround6 said:


> Timing, Timing,Timing.
> 
> *When the Whirlwind was* entering production and *first entering squadron service* the Warhawk and Mustang pretty much existed as drawings on paper and parts being assembled into prototypes.



The first operational Whirlwind unit was No. 263 Squadron and that was declared operational with the Whirlwind on 7 December 1940. 

But the P-40 was only a few months behind and was equipping far more than three squadrons only 6 months later.

P-40s first saw combat with the British Commonwealth squadrons of the Desert Air Force in the Middle East and North African campaigns, during June 1941
The Model Bs were received by Chennault at the end of 1941 
The 24th Pursuit Group in the Philippines received their first P-40s in early 41 and their first Es well before PH.

Yes the Mustang was over a full year behind and first operational in the RAF in January 42.

That said I still put the Whirlwind third only to the Hornet and Mosquito as the best looking Brit fighters and I think if a better engine was available it would have been a winner. The only possible engine that comes to mind is the Pratt Hornet and that was at the end of its life and probably not worth developing further so that was not a viable option.


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## wuzak (Jan 5, 2020)

MiTasol said:


> That said I still put the Whirlwind third only to the Hornet and Mosquito as the best looking Brit fighters and I think if a better engine was available it would have been a winner. The only possible engine that comes to mind is the Pratt Hornet and that was at the end of its life and probably not worth developing further so that was not a viable option.



Also several hundred horsepower short of the Peregrine.


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## Shortround6 (Jan 5, 2020)

MiTasol said:


> The first operational Whirlwind unit was No. 263 Squadron and that was declared operational with the Whirlwind on 7 December 1940



That is true but I believe No 25 squadron got a few in the summer of 1940, granted more in the nature of operational trials than actual operations. I would note that the original statement by another poster said "Warhawk" and not Tomahawk and the Warhawk would not even fly until May 7th 1941 (P-40D)




MiTasol said:


> That said I still put the Whirlwind third only to the Hornet and Mosquito as the best looking Brit fighters and I think if a better engine was available it would have been a winner. The only possible engine that comes to mind is the Pratt Hornet and that was at the end of its life and probably not worth developing further so that was not a viable option.



The Whirlwind didn't need a "better" engine, it neede the one it had sorted out and/or those hydraulic throttle controls gotten rid of. 

Take a Spitfire, screw up the intake ducts to lessen the Ram (Vokes filter?), take away the ejector exhausts (or reduce their efficiency substantially ) and fit them with that lousy throttle control (which sometimes had to be "bled" several times in one flight) and see what happens to performance and reliability.


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## Reluctant Poster (Jan 5, 2020)

Kevin J said:


> Here's the photo that I saved to my laptop. I'll have a look for the forum next.
> View attachment 565633


That installation looks virtually identical to the Peregrine powered Gloster F9/37.
WT Live // Image by MiniMeteor

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## MiTasol (Jan 5, 2020)

Shortround6 said:


> That is true but I believe No 25 squadron got a few in the summer of 1940, granted more in the nature of operational trials than actual operations. I would note that the original statement by another poster said "Warhawk" and not Tomahawk and the Warhawk would not even fly until May 7th 1941 (P-40D)



Actually in US service every P-40 variant was a Warhawk.

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## MiTasol (Jan 5, 2020)

Shortround6 said:


> The Whirlwind didn't need a "better" engine, it needed the one it had sorted out and/or those hydraulic throttle controls gotten rid of.
> Take a Spitfire, screw up the intake ducts to lessen the Ram (Vokes filter?), take away the ejector exhausts (or reduce their efficiency substantially ) and fit them with that lousy throttle control (which sometimes had to be "bled" several times in one flight) and see what happens to performance and reliability.



I totally agree about that stupid throttle system but it is British so what do you expect. I know virtually nothing about the engine itself except that it was notoriously unreliable and that RR did not adequately support it as they wanted to put all their efforts into the Merlin. Westlands exhaust and intake designs were no doubt the cause of performance losses as well


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## TheMadPenguin (Jan 9, 2020)

1: Mr Richard Gatling invented a method for disposing of ammunition in a hurry back around 1960. It's known as the Gatling gun. 1939 tech could couple electric or hydraulic drive for faster burst firings, steeper cam for fewer barrels, and round-counters as burst limiters. .30, .50, and .80 (20mm) Gatlings, weighing less than two guns and firing faster than three guns, could increase destructive power considerably.


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## wuzak (Jan 9, 2020)

TheMadPenguin said:


> 1: Mr Richard Gatling invented a method for disposing of ammunition in a hurry back around *1960*. It's known as the Gatling gun. 1939 tech could couple electric or hydraulic drive for faster burst firings, steeper cam for fewer barrels, and round-counters as burst limiters. .30, .50, and .80 (20mm) Gatlings, weighing less than two guns and firing faster than three guns, could increase destructive power considerably.



Wrong century.


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## Shortround6 (Jan 9, 2020)

A big problem is not getting rid of the empties, but feeding the ammo to the gun. It doesn't matter what rate the gun will fire at if you can't get the ammo to the gun. And in fighters you have to do it while pulling 4 "G"s or more. What weight of ammo over what distance?


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## Admiral Beez (Jan 9, 2020)

Give the Zero and the Ki-43 a sufficiently powerful engine to allow for the weight of hydraulic controls, armour, self sealing fuel tanks, greater firepower and ammunition capacity. Basically I’m suggesting the Nakajima Ki-84.

There‘s nothing on the Ki-84 or its Nakajima Homare engine that was evolutionarily unlikely or technologically infeasible in the late 1930s to be in frontline service by Dec 1941. Make it a single type (fixing the Ki-84’s weak undercarriage and add folding wings) for both the IJN and IJAF to streamline the types and production capacity.


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## tyrodtom (Jan 9, 2020)

Only think wrong with the gatling gun during the WW2 era is, it's a big gun, and has to be installed as a whole system. the magazine fairly close to the gun.

You couldn't mount it in the center of a single engine aircraft, because it couldn't be synchronized .
So even if it was as small as .30 caliber, that would be a pretty big chunk to put in each wing


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## MiTasol (Jan 9, 2020)

and I doubt it would fit in the nose of a P-38 It would fit in the nose of a P-61 if you stripped the radar out but then your night fighter becomes a day fighter


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## Shortround6 (Jan 9, 2020)

Admiral Beez said:


> There‘s nothing on the Ki-84 or its Nakajima Homare engine that was evolutionarily unlikely or technologically infeasible in the late 1930s to be in frontline service by Dec 1941. Make it a single type (fixing the Ki-84’s weak undercarriage and add folding wings) for both the IJN and IJAF to streamline the types and production capacity.




There is nothing "evolutionarily unlikely or technologically infeasible" in Britain making Griffon powered Spitfires in late 1940 or early 1941 either. Or the US making P-47s in 1941 or..............................


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## Shortround6 (Jan 9, 2020)

MiTasol said:


> and I doubt it would fit in the nose of a P-38 It would fit in the nose of a P-61 if you stripped the radar out but then your night fighter becomes a day fighter


 It might be able to fit a pair in the belly bulge where the 20mm guns were. 

But unless you can figure out how to feed the things (move .50 cal or 20mm belted ammo 3-6 times faster than "normal" WW II guns you aren't going to get very far.

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## Admiral Beez (Jan 9, 2020)

Shortround6 said:


> There is nothing "evolutionarily unlikely or technologically infeasible" in Britain making Griffon powered Spitfires in late 1940 or early 1941 either. Or the US making P-47s in 1941 or..............................


Fair point. But what I meant was by late 1941 and into 1942 when Japan was still primarily flying 940 hp, lightweight and fragile Zeros and Oscars, most European and US single engine fighters had the horsepower, firepower, hydraulics and armour that I suggest. For example, in Nov. 1941 the Spitfire Mark V was in service with over 1,450 hp, and the first Griffon-powered Spitfire has just flown with over 1,750 hp. It‘s not fantasy to propose Japan look at everyone else and find the same.


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## Shortround6 (Jan 9, 2020)

Few, if any, single engine fighters (or even multi engine) were using hydraulic flight controls in 1941-42, it took until early 1944 (?) for the P-38 to get powered ailerons. 

The British got 1450hp Merlins in 1941 (and I would really check on that, the Merlin 45 in the MK V had it's boost limit raised several times, and even at 12lbs boost instead of 9lbs it was a few hundred HP short of 1450hp) because the British fuel was a lot better and allowed higher boost. 

It is fantasy to propose 1944 engines in 1941. 
See how long and how much trouble P & W had with the crankshaft of the R-2800 for instance. 
Getting high powered aircraft engines to properly cool, for their bearings to work and and to get the vibrations levels down to an acceptable limit was not easy. 

The Homare used the same size (bore and stroke) cylinders as the Sakae engine. If you had built the 18 cylinder Homare engine in 1941 and didn't change the supercharger, or the manifold pressure or the rpm from the Sakae 11 you would have gotten an engine of around 1265hp, not 1800-2000hp.

you needed to change something or several somethings to get the power per liter up the level of the Homare engine of 1944.

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## MiTasol (Jan 10, 2020)

Shortround is right when he says *It is fantasy to propose 1944 engines in 1941.*

Remember that the 1,525 hp Wright R-1820 built in the 1950s started life at 700 hp in 1931.
Even if you have a good basic engine it takes years to get maximum power and good reliability out of it.

The Pratt R-1830 likewise grew from 800 hp in 1932 to 1350 hp in the mid 40s.

The Sakae was first *RUN *in 1939. It did not have almost 10 years of development like the Pratts and Wrights did by 1941 yet it had a remarkably low sfc and reasonable reliability from day one.

Both American manufacturers were into production runs far greater than any Japanese engine long before 1941 and much development comes from the experience gained by running the engines in flying aircraft. Until any engine is in service in numbers (in the days before computers) you had no way of knowing if that cracked cylinder head or other defect is a one off, a result of the powerplant design, a result of pilot mismanagement, of pilot training, bad manufacturing, or truly an engine design fault. Even when a problem became known it still took a lot of research to determine the cause - look at the Allison reliability in the P-38 as an example. All caused by the pilots obeying the USAAC flight manual instead of Lockheed and Allison's operating instructions.

Even now on computer designed FADEC engines with the aircraft effectively flown by the FMC computer the same applies (both of which take most pilot problems off the list). Just look at all the problems operators of the newer Rolls Royce Trent engines have been having for the last five years.
Design problems on an engine has been in operation for almost 30 years. Maybe they have kept the Trent going beyond its practical stretch limits?


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## swampyankee (Jan 10, 2020)

To expand what MiTasol said: P&WA and CW had a lot of those engines in commercial service pre-war. Commercial aircraft spend much more time flying than military ones (the expected usage of the CH-53 by the USMC was 360 hours per year; this may be lower than expected usage of military combat aircraft in the 1930s but the Marines did not pull that number from their collective behinds: they got it from peacetime and Vietnam-era usage. In contrast, commercial users would be looking at something like ten to fifteen times that. A commercial plane on the ground is losing money. A military plane on the ground isn’t costing money)


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## Shortround6 (Jan 10, 2020)

Admiral Beez said:


> It‘s not fantasy to propose Japan look at everyone else and find the same.


 The Japanese were looking. 

Ki -44 first flight Aug 1940
KI-60 first flight March 1941
Ki-61 first flight Dec 1941

For the navy and from wiki
"Towards the end of *1940*, the Imperial Japanese Navy asked Mitsubishi to start design on a 16-_Shi_ carrier-based fighter, which would be the* successor to the carrier-based Zero.* At that time, however, there were no viable high-output, compact engines to use for a new fighter. In addition, Jiro Horikoshi's team was preoccupied with addressing early production issues with the A6M2b as well as starting development on the A6M3 and the 14-_Shi_ interceptor (which would later become the Mitsubishi J2M Raiden, a land-based interceptor built to counter high-altitude bombers). As a result, work on the Zero successor was halted in January 1941."

J2M Raiden first flight March 1942. 


Unfortunately the phrase "_evolutionarily unlikely or technologically infeasible_" opens up a bunch of possibilities that tend to fall apart upon closer examination. 

Take the Bristol Hercules engine, problems with sleeve valves aside, it went from a 1300-1400hp engine in the late 30s (in development and testing) to a 2100hp engine at the end of the war or post-war. It was NOT done by pouring higher PN number fuel into the tanks and screwing the boost control adjusting screw down. 
Everything that was done _could be_ considered evolutionary and technically feasible (although the last is questionable) in 1940-41. However along the way (evolutionary) the Hercules went through 7 different cylinder head designs with ever increasing finning for better cooling, early heads were cast and machined, later heads were forged and machined. Yes forging was known but how much forging capacity did they have in the early years? I believe (open to correction) that the last engines (200, 600 and 700 series) got alloy heads with a very high percentage of copper(if not mostly copper) for better heat transfer. While not technologically infeasible in 1930-41 (?)(depends on the state of the metallurgy) it is a major problem in wartime to be using pounds of copper per engine for better cooling fins. The later engines also got a new crankcase and crankshaft with larger bearings. 

The Wright R-1820 has been mentioned already is a classic case of "improvements" as the engine could be considered a series of engines of at least 5 engines that share a common bore and stroke (and sometimes mounting points and propshaft spline) as the engine went from 600 to 1525hp. 

The arguments and improvements start to get circular in that there was no reason to design and try to build the later "style" of engine early when the fuel was only 80 octane and the engine was limited to 1900-1950rpm. As better fuel became available, the compression or boost could be raised and as better ways of manufacturing cylinders with more fin area were developed (an often overlooked aspect of air cooled engine design) the rpm could be increase (along with better bearings and vibration dampers) as the heat load increased. 
The early 1930s R-1820E went 850lbs without reduction gear. The 1950s 1525hp R-1820 for use in Helicopters went over 1400lbs without reduction gear. there is no sense building a 1200-1300lb 30 liter engine if the available fuel will only support 600-700hp. 
One book notes the changes between the 1100hp R-1820G100 engines and the 1200hp R-1820G200 engines as (but not limited to) a new crankcase (both are steel but not interchangeable) and increase from 2800sq in of finning on the cylinder barrel and head to 3510 sq in. (this is per cylinder), the exhast valve is changed in shape to give more volume for the sodium filling. The exhaust valve guides are more streamlined and the area of the exhaust port is increased by 20%, The intake pipes from the supercharger diffuser to the inlet port of the heads was increased in size. There was a new oil scavenging system. The crankshaft had a double vibration damper instead of a single vibration damper. The supercharger diffuser had 12 blades instead of 9 blades although the impeller was the same size.

This was to go from 2350rpm and 1100hp max to 2500rpm and 1200hp max. 

I have no idea what the Japanese did to go from about 70hp per cylinder on the Sakae 11 to 111hp per cylinder on the Homare but there was obviously a LOT of development.


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## tomo pauk (Jan 10, 2020)

Shortround6 said:


> ...
> I have no idea what the Japanese did to go from about 70hp per cylinder on the Sakae 11 to 111hp per cylinder on the Homare but there was obviously a LOT of development.



Partial answers:
- Steel crankcase + counterweights on the crankshaft = better rpm (2900-3000 vs. 2700-2800). 
- increase of manifold pressure to +500 mm Hg via ADI, vs. +300 for the latest Sakae without ADI (due also to better crankcase + crankshaft?)
- size/material/type of valves?
- better pistons, crankpins?
- per TAIC, the Homare 20 series have had increased compression ratio - from 7:1 to 8:1 (my comment - if true, it was a nice way to shot oneself into foot)

Unfortunately, we don't seem to have good data on Army's Sakae (Ha 112) with ADI.

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## Admiral Beez (Jan 10, 2020)

MiTasol said:


> Shortround is right when he says *It is fantasy to propose 1944 engines in 1941.*


I see your point. Let's avoid fantasy. My thinking was to give the Japanese hp levels that others were getting from radials at the time. Can we get the Japanese some influence from the Fw 190's BMW 801 for instance?


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## tomo pauk (Jan 10, 2020)

Admiral Beez said:


> I see your point. Let's avoid fantasy. My thinking was to give the Japanese hp levels that others were getting from radials at the time.



Japanese radials were either equal or slightly better than Soviet, German or British radials, and far better than Italian radials.



> Can we get the Japanese some influence from the Fw 190's BMW 801 for instance?



Single-lever operation (Kommandogeraet), direct injection?
Japanese improved the layout of exhaust stacks at the BMW 801 level by some time 1943-44


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## Shortround6 (Jan 10, 2020)

You have two or three different problems making high powered aircraft engines for service use. 

1. is just getting the engine to make high power for any period of time. This requires either high BMEP (usually high boost) or high rpm or both.
2, getting the engine to survive for even a few minutes, too high a BMEP level (too much boost/compression) for a given type of fuel leads to detonation and wrecked engines pretty quick. 
3, Getting the engine to survive the power level desired for a worthwhile amount of time in squadron service. The Russians would tolerate an engine life of 50 to 100 hours while the US and Britain would not. If you are going to send planes halfway round the world you want to send about 20-25% spare engines and not 2-3 engines per airplane. 

When things get desperate you may accept lower service life, but there was a continual battle between more power and long engine life. 
The Allison went through 4 different crankshafts. the first 3 look identical, plain alloy steel followed by shot peening, followed by shot peening and nitriding and finally a crankshaft with both shot peening, nitriding and 27lbs worth of extra counterweights. Please note the last crankshaft could be put in an early engine and there was no change in the size/dimensions of either the main bearings or the rod bearings yet fatigue life went up by an order of magnitude. (later engines may have gotten better bearings?). 

The Japanese actually weren't doing too badly.
Problem is the BMW 801 was a 41.8 liter engine. 
The Kasei engine was 42 liters and Kinsei engine was only 32.3liters. 
The American R-2600 was 42.6 liters
The Hercules was 38.7 liters (as were the Gnome Rhone 14K, 14N and 14R and their cousins) 

There was no magic technology that was going to overcome the displacement gap, especially considering the Japanese fuel situation.

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## jetcal1 (Jan 10, 2020)

Shortround6 said:


> You have two or three different problems making high powered aircraft engines for service use.
> 
> 1. is just getting the engine to make high power for any period of time. This requires either high BMEP (usually high boost) or high rpm or both.
> 2, getting the engine to survive for even a few minutes, too high a BMEP level (too much boost/compression) for a given type of fuel leads to detonation and wrecked engines pretty quick.
> ...


Like it or not, fuel (Octane) is the magic elixir that will unleash the most horsepower all other things being equal. After you hit the horsepower target you start doing the engineering clean-up to fix the weak links in the design chain. 
After that? you'd better have a Stanley Hooker on your staff who can find the hidden horsepower and the engineering staff to start fixing the new weak links caused by the increase in horsepower.

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## Kevin J (Jan 10, 2020)

Shortround6 said:


> You have two or three different problems making high powered aircraft engines for service use.
> 
> 1. is just getting the engine to make high power for any period of time. This requires either high BMEP (usually high boost) or high rpm or both.
> 2, getting the engine to survive for even a few minutes, too high a BMEP level (too much boost/compression) for a given type of fuel leads to detonation and wrecked engines pretty quick.
> ...


Until the LA-5FN arrived in 1943 and the Yak-3 arrived in 1944, everything the Russians had was outclassed from 1941, so they had no choice, it was either the engine or the pilot. At least us Brits had the Spitfire IX and Typhoon from 1942, the Americans, the P-38J/L, P-47D and P-51B/C/D from 1943/44.


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## MiTasol (Jan 10, 2020)

swampyankee said:


> To expand what MiTasol said: P&WA and CW had a lot of those engines in commercial service pre-war. Commercial aircraft spend much more time flying than military ones (the expected usage of the CH-53 by the USMC was 360 hours per year; this may be lower than expected usage of military combat aircraft in the 1930s but the Marines did not pull that number from their collective behinds: they got it from peacetime and Vietnam-era usage. In contrast, commercial users would be looking at something like ten to fifteen times that. A commercial plane on the ground is losing money. A military plane on the ground isn’t costing money)



In the 30's an efficient operator was probably getting about 6 hours utilization per day because very little night flying was done and heavy maintenance kept the aircraft (and engines) on the ground for a couple of weeks per year. For every DC-2 or Boeing 247 that means every aircraft flew over 4000 engine hours per year.

Engine time may have been as high as 4 to 5 hours per day as engines had relatively low overhaul lives and overhauls took time. Still that puts a civil engine at operating possible up to somewhere around 1500 to 2000 hours per year, depending on how fast the overhaul was and how few spares the operator carried. 

When I was last directly involved in jet maintenance in the 90's the 767-300ER aircraft in the hands of most efficient long haul operators were averaging over 14 hours flying time a day for 365 days a year. One operator was pushing 16 hours per day on extra long haul ops. With long haul the hours between overhaul when the aircraft is averaging 10 hour legs are way beyond what any piston engine can ever dream of and usually come down to the life limit of components.

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## swampyankee (Jan 10, 2020)

2000 flight-hours/year is still several times the likely usage for most military aircraft, especially fighters. Patrol aircraft may be above that.


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## MiTasol (Jan 10, 2020)

Admiral Beez said:


> Give the Zero and the Ki-43 a sufficiently powerful engine to allow for the weight of hydraulic controls



Why?
Hydraulic controls are needed when you cannot get the aerodynamics right. The Sabre has boosted controls and they killed a number of pilots including one of Reno's premier racing Merlin builders when they locked up.
The Mig 15 only has boosted aileron and fly's quite nicely with the boost off until you reach the higher end of its speed range.
If you ever watched DC-9s and MD-80 series aircraft start and taxi it was not unusual to see one elevator up and the other down. They used servo tabs instead of hydraulics.

Why add weight, complexity and more things to go wrong unless there is no other option?


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## swampyankee (Jan 10, 2020)

I think the only WWII-era fighter with hydraulically boosted controls was the P-38. They weren’t needed, as far as I know on any of the single engine piston fighters. A bit later, the B-47 used boosted controls but the B-52 (at least earlier models) and the 707 used servotabs.


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## Shortround6 (Jan 10, 2020)

MiTasol said:


> In the 30's an efficient operator was probably getting about 6 hours utilization per day because very little night flying was done and heavy maintenance kept the aircraft (and engines) on the ground for a couple of weeks per year. For every DC-2 or Boeing 247 that means every aircraft flew over 4000 engine hours per year.


 This is not quite right, at least in the US. Due to the distances in the US overnight sleeper services started fairly early. 





21 of these were built in 1933/34 with berths for 12 passengers. 
The Overnight sleeper market was the main idea behind the DC-3, originally called the DST (Douglas Sleeper Transport) They wanted a plane that would hold as many passengers in sleeper berths as the DC-2 would carry in seats. Hence the fatter fuselage (which wound up seating 3 across normally and 4 across in crowded (for the 1930s) conditions. 

Engine overhauls were rarely done in airline shops (although top end overhauls/repairs might be) engines were swapped out when they needed to be overhauled. The planes had to be kept in the air to make money and trying to overhaul the engines took too long. Daily averages are hard to come by but the DSTs were flying Between Chicago and New York in June of 1936 and a 10 hour non stop between Los Angles and Chicago in July. Coast to coast (with stops) was started in Sept. 
By 1937 the DC-3s in a number of interior layouts (14 seat club car or sky lounge) 21 seat standard and up to 28 seats. but planes were being tasked with flying all the way from New York to San Francisco (with stop/s)The planes were refueled as a SOP and not changed during the stop/s unless something needed seeing to. 
By Nov of 1937 United Airlines had completed it's 20,000th coast to coast trip ( started before the DC-3) and other air lines on other routes certainly added substantially to that number. 

Obviously US AIrlines placed a premium on reliability and durability.

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## MiTasol (Jan 11, 2020)

Shortround6 said:


> This is not quite right, at least in the US. Due to the distances in the US overnight sleeper services started fairly early.
> 21 of these were built in 1933/34 with berths for 12 passengers.
> The Overnight sleeper market was the main idea behind the DC-3, originally called the DST (Douglas Sleeper Transport) They wanted a plane that would hold as many passengers in sleeper berths as the DC-2 would carry in seats. Hence the fatter fuselage (which wound up seating 3 across normally and 4 across in crowded (for the 1930s) conditions.
> Engine overhauls were rarely done in airline shops (although top end overhauls/repairs might be) engines were swapped out when they needed to be overhauled. The planes had to be kept in the air to make money and trying to overhaul the engines took too long. Daily averages are hard to come by but the DSTs were flying Between Chicago and New York in June of 1936 and a 10 hour non stop between Los Angles and Chicago in July. Coast to coast (with stops) was started in Sept.
> ...



Yes and no.

Yes there were a number of overnight sleeper operations and yes the DC-3 started as the DST but as a percentage of the total airline fleet do not think that these aircraft were that significant a percentage of total fleet hours. I could be wrong of course. I would also add that long before the sleeper services started the majority of mail and some freight flew at night. Again as a percentage of the whole I believe that this was not that significant.

And yes engines were swapped out, not overhauled while the aircraft sat around idle. That is why I said that aircraft were doing some 2000 hours per year and engines up to 1500. Depending on the engine an operator would hold 30-100% spares for this reason (making my estimation of about 1500 way too high). Many operators did their own engine and component overhauls as depending on the manufacturer could result in your engines being held up in overhaul by brand X's engines so having your own shop guaranteed your engines got priority and were done the way you wanted.

Ten hours non stop for a DC-3 sounds like they were pushing the limit somewhat as my (very fallible) memory is that the DC-3 did not have that endurance. I will have to check.
*EDIT - *According to the USAAF C-47 flight manual the C-47 had an endurance of 11.82 hours if you made no allowances for take off and climb so that does make 10 hour flight possible but they would definitely be running on the smell of an oily rag on landing and have nothing in reserve. I suspect the earlier engines were a little less fuel efficient than the 1830-92 which would have shortened the range a little as well. I cannot find my DC-2 flight manual.


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## Zipper730 (Jan 12, 2020)

MiTasol said:


> Shortround is right when he says *It is fantasy to propose 1944 engines in 1941.*


Agreed. Read the first page...


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## pinehilljoe (Jan 12, 2020)

Shortround6 said:


> This is not quite right, at least in the US. Due to the distances in the US overnight sleeper services started fairly early.
> View attachment 566385
> 
> 21 of these were built in 1933/34 with berths for 12 passengers.
> ...



What aircraft is shown in the photo?


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## swampyankee (Jan 12, 2020)

pinehilljoe said:


> What aircraft is shown in the photo?


I think it's the Curtiss T-32.


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## MiTasol (Jan 12, 2020)

Also known as Curtiss Condor. The T32 had fixed pitch props and the AT32 had two pitch props. 
Curtiss T-32 Condor II


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## Koopernic (Jan 12, 2020)

MiTasol said:


> Why?
> Hydraulic controls are needed when you cannot get the aerodynamics right. The Sabre has boosted controls and they killed a number of pilots including one of Reno's premier racing Merlin builders when they locked up.
> The Mig 15 only has boosted aileron and fly's quite nicely with the boost off until you reach the higher end of its speed range.
> If you ever watched DC-9s and MD-80 series aircraft start and taxi it was not unusual to see one elevator up and the other down. They used servo tabs instead of hydraulics.
> ...



While the servo tab is an German invention (by Flettner) and was widely used in WW2 bombers and transports its perfection as the geared spring tab came from the NACA in the 1940s which allowed the technology to be expanded over a wider speed range than just bombers. The later war Hellcat and Corsair received them and it seems to have doubled high speed roll rate but at a noticeable expense in low speed roll rate. The P-38 received hydraulic boosted ailerons and enjoyed a massive increase in roll rate without it effecting low speed roll. 

Traditional spring tabs tended to deflect too much at high speed which would destroy the pilots linear force feedback and he could over stress(destroy) the airframe at high speed. What I'm saying is it was an American invention unknown. The Arado 234 apparently had them and so the Germans may have figured them out but they used hydraulics on the Do 335.

The problem with spring tabs of any kind is that they are finicky to design and can be prone to flutter. Once you are in the supersonic speed range they are completely inadequate and can even reverse. American Eagle 4184 (An ATR 72) crashed because icing on the NACA 5 digit air foils led to the ailerons reversing, the aircraft inverting and a total loss of the hull and all souls. Admittedly that was the case of the FAA rusting a badly done French (Pre EASA) certification re icing.

Nevertheless geared spring tabs allowed the B36 to be flown with no trouble without boosted controls. If you go to the B737 site there is some interesting photos of the elevator spring tabs along side of which are anti balance tabs to keep the force feedback linear.

Supersonic aircraft have fully hydraulic controls not boosted because they can not tolerate any forces getting back to the pilot which may cause PCO pilot coupled oscilations. They artifical feel applied from a pitot static tube.

Because of the spacious trailing edge of the P51 laminar profile wing it used internal pressure balancing where for instance if a aileron was deflected up the high pressure air was channeled to a bellows to reduce airleron force.

Of course your trying to stop the pilot over stressing the airframe. If you have fly by wire the practice is to simply reduce deflection as speed goes up.


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## Jugman (Jan 12, 2020)

MiTasol said:


> Yes and no.
> 
> Yes there were a number of overnight sleeper operations and yes the DC-3 started as the DST but as a percentage of the total airline fleet do not think that these aircraft were that significant a percentage of total fleet hours. I could be wrong of course. I would also add that long before the sleeper services started the majority of mail and some freight flew at night. Again as a percentage of the whole I believe that this was not that significant.
> 
> ...




Most DC-3 were Cyclone powered, which were more fuel efficient than the Twin Wasp. In any event prewar models of both engines should have equal or slightly better fuel efficient do to less friction and lighter construction of moving parts. The typical DC-3 was a good 600-1500lbs lighter empty than a C-47 as well. 

From the R4D-5 SAC sheet combat range for the R4D-3 was:
1295 n.mi./111kts @ 29000lbs
1405 n.mi./107kts @ 26000lbs
Both aircraft have the same fuel load of 4824lbs.

Cruising altitude was 1500ft. There is no breakdown of allowances if there are any. Because SAC sheets were designed as practical aides for mission planing, I suspect these range figures are most likely practical with allowances for

That 11.82 hours is based on the minimum specific fuel consumption rate 34 gph at 450hp. This is neither the minimum fuel consumption to maintain level flight nor the power for best range.


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## MiTasol (Jan 12, 2020)

Jugman said:


> Cruising altitude was 1500ft.
> That 11.82 hours is based on the minimum specific fuel consumption rate 34 gph at 450hp. This is neither the minimum fuel consumption to maintain level flight nor the power for best range.



You are right of course but I would comment that

as a quick calc a sfc of 34gph was the only figure that produced the ability to remain airborne for 10 hours. Your navy numbers give 13 hours at 107kts which shows that I should have done my homework. I never bothered keeping my old DC-3 ops manuals. 
1,500 feet cruising altitude will get you killed in most places over land. I first thought that you had left out a zero but 15,000 feet was never a option either so that must be for over water ops
*IF* memory is correct in the early 70's with -92 engines the Dak used over 70 imp gal/hour (72igph??) at 7,000ft, 2050rpm and 26" giving a 115mph cruise clean at a normal operating weight of 23,000lbs. With max usable fuel at 690 Imp gals that gives under ten hours fuel even before allowances for takeoff/climb/45mins reserve/etc are included so I still do not see how the Navy and overnight sleeper operators got their endurance. As you say the tankage is identical. The early Cyclones must have been significantly lower in fuel consumption but that that does not cover the Navy R4D-3 with Pratt -92s unless the lower altitude made a massive difference. Maybe the Navy did not carry deicer boots but I cannot see that helping that much either.


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## Shortround6 (Jan 13, 2020)

I would note that the commercial DC-3s (and DSTs) of the 1930s didn't use the same engines as the C-47. 

When the DST was introduced in 1936 it used Wright GR-1820-G2 engines rated at 850hp at 5800ft and 930hp for take-off, but max fuel may have been 650 gallons. 
I would also note that the 10 hour flight mentioned above was from Los Angles to Chicago and flight times were often several hours different between east bound and west bound flights coast to coast due to the prevailing winds out of the west. 

A lot depends on what power settings were used as the older/lower powered engines could make about 75% power on around 100 gallons an hour. 

By the time you get the P & W R-1830 powered planes (about 6 months later) the R-1830 being used was the SB3G engine rated at 1100hp for take-off and 900hp at 8,000ft (single speed supercharger), cruising speed at 75% power was 196mph and that took 100gph. standard fuel was 650 gallons and max fuel was 822 gallons. 
Max gross weight of these planes 24,400lbs but the sleeper planes and "Skylounge" often ran light.


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## Zipper730 (Jan 14, 2020)

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## Admiral Beez (Jan 14, 2020)

Admiral Beez said:


> Hawker Typhoon. Fix the tail at the onset, get a reliable and mass produced Sabre or Centaurus engine into the Typhoon by end 1940. Send four squadrons to Malaya in early 1941, eight more by October 1941.





MiTasol said:


> Centaurus production started in 1942 so it would be difficult to _send four squadrons to Malaya in early 1941, eight more by October 1941._
> 
> And yes I do know it first ran in 1938 but is was not produced until 1942 because Bristol needed to improve the reliability of their entire sleeve valve engine line and it did not make it into any ww2 aircraft


Fair enough. Then let's just fix the tail. That surely meets the criteria of this thread.


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## Jugman (Jan 14, 2020)

Raising the altitude several thousand feet shouldn't hurt endurance to much. 
Either your weight or your speed is way off. A DC-3 at that weight and speed should cruise on 1800 rpm 26" was fuel consumption of no more than 75 usgal an hour.
This is somewhat moot because the DC-3 can fly somewhat faster than what I posted above with little penalty to range. 98% the range for 60% the flight time seems pretty worth it to me.


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## Zipper730 (Jan 22, 2020)

I'm curious when the Vickers Long-Range High-Altitude "Victory Bomber" and Vickers Windsor were first floated as proposals? I figure that, if the Windsor came later, one could have devoted the effort to the building the Windsor into the High-Altitude Bomber proposal.

The problem with the Vickers High Altitude bomber was that, it was designed only with the provisions to deliver a 22,000 pound bomb. From what I remember reading, it seemed that Wallis did eventually amend the design to carry up to 32,000 pounds of ordinance, or a 22,000 lb. "Grand Slam", over a considerable distance, but it was too late: However, if the design was simply built around carrying a 22,000 pound Grand Slam, or regular ordinance from the start, it seems like it would have been a great design. With the ability to operate around 40,000 to 45,000 feet, it'd be extremely difficult to catch.

Given that the Windsor had a maximum payload 17,000 pounds less, with a top-speed 35 miles an hour lower, at a cruising altitude 9,000-14,000 feet lower, with (potentially) less range: I see the earlier design as being better in principle.


G
 Glider
, 

 GrauGeist
, 
S
 Shortround6
, 

 swampyankee
, 
W
 wuzak


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## Admiral Beez (Jan 22, 2020)

I have to think the Blackburn Skua could have been made more aerodynamically streamlined. Petter from Westland Whirlwind fame should be able to smooth out some of the Skua's dreadful lines, starting with the vertical windshield.


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## tomo pauk (Jan 22, 2020)

Once could argue that Skua was far more streamlined than Ju-87 or Aichi Val - retractable U/C vs. fixed, and no 'dropped' flaps like the Ju 87 had. Where it lacked was 'under the hood', 900 HP is not going to enable much more than it was historically so.


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## Admiral Beez (Jan 22, 2020)

tomo pauk said:


> Once could argue that Skua was far more streamlined than Ju-87 or Aichi Val - retractable U/C vs. fixed, and no 'dropped' flaps like the Ju 87 had. Where it lacked was 'under the hood', 900 HP is not going to enable much more than it was historically so.


I see what you mean, but this vertical windshield and all these protrusions near the engine, under the wings and fuselage plus that tail wheel must rob some speed. I'm no aerodynamicist, but there's probably another 20-30 mph in top speed easy here.

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## tomo pauk (Jan 22, 2020)

Admiral Beez said:


> I see what you mean, but this vertical windshield and all these protrusions near the engine, under the wings and fuselage plus that tail wheel must rob some speed. I'm no aerodynamicist, but there's probably another 20-30 mph in top speed easy here.
> 
> View attachment 567482



Protrusion under the engine is the ram air intake - that is going to stay where it was. Granted, the bomb racks for small bombs (flares?) are as draggy as it gets, that needs some rework indeed, so does the tail wheel. As for the windscreen - install a 'false windscreen' in front of the existing one? OTOH - engine was firmly behind the curve by 1940. 
All in all, perhaps going with Fulmar or Henley as a dive bomber nets you a better solution for 1939-42?

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## Zipper730 (Feb 15, 2020)

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## Zipper730 (Mar 17, 2020)

wuzak said:


> I can't remember if the He 177 was originally proposed and designed without provision for dive bombing, but the requirement for dive bombing was added later causing delays and structural issues.


There was some glide-bombing requirement. I've bought a book or two on this and there was no real clear answer, Eric M. Brown's book on the Luftwaffe's aircraft also seemed to bear no useful information except that the dive requirements were increased to 60-degrees after the Spanish Civil War. Maybe there's a source with more detail out there, but I haven't been able to find it.



GrauGeist said:


> The He177 was purely conceived as a strategic heavy bomber in answer to the RLM's "Bomber A" program, which would have seen it penetrate into Soviet airspace to strike industrial targets.


They wanted to fly to the Urals and back right? That's a round trip of something like 3500 miles from Berlin. From what I recall, they wanted a speed of 500 kph, a provision for shallow/moderate glide-bombing capability pretty early on, not sure what cruise altitude they wanted. They seemed really fixated on having two props over four. I know it was based on installation drag, but it was all of 3%. Now that's significant at speeds in the 300 mph range, but they were planning to use surface evaporative cooling which would greatly improve climb performance, and lower overall drag. The landing-gear would have been easier to work out if the propellers weren't so large.


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## Zipper730 (Mar 18, 2020)

kmccutcheon
, 
S
 Shortround6
, 
W
 wuzak


Regarding the Hyper Engine: From what I remember, it would have been possible for the USAAC to have simply changed the contract terms for the V-1008 to the IV-1430 from single cylinder to mono-block to single-cylinder at any point in time. Would that have been a good idea to have done so?

As for two valves per cylinder: The first development of four-valves per cylinder in a reciprocating engine was in 1916. I'm not sure when it first appeared in aircraft-engines, though it seemed to be there in the 1930's.


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## GrauGeist (Mar 18, 2020)

Zipper730 said:


> They wanted to fly to the Urals and back right? That's a round trip of something like 3500 miles from Berlin. From what I recall, they wanted a speed of 500 kph, a provision for shallow/moderate glide-bombing capability pretty early on, not sure what cruise altitude they wanted. They seemed really fixated on having two props over four. I know it was based on installation drag, but it was all of 3%. Now that's significant at speeds in the 300 mph range, but they were planning to use surface evaporative cooling which would greatly improve climb performance, and lower overall drag. The landing-gear would have been easier to work out if the propellers weren't so large.


The Grief was an answer to the "Bomber A" program after the "Ural Bomber" request produced few results. It had impressive range with a light bomb load, but like most heavy bombers, it's range was drastically reduced if it carried it's max. load of 15,000 pounds.
The major issue Heinkel had, was the engines overheating and subsequent fires, just like the US had with the B-29.

The "glide bombing" doctrine hampered development, as with other types, as it stressed large Airframes - the RLM was infatuated with everything being dive-bomb capable and they really screwed themselves with that fixation.
Imagine the USAAC requiring the B-17 to have the same requirement and how long it would have taken Boeing to make it happen...

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## Zipper730 (Mar 18, 2020)

GrauGeist said:


> The Grief was an answer to the "Bomber A" program after the "Ural Bomber" request produced few results. It had impressive range with a light bomb load, but like most heavy bombers, it's range was drastically reduced if it carried it's max. load of 15,000 pounds.


Do you have any data that indicates the specs that were dictated? Speed, altitude, range, payload over range, maximum payload, etc...


> The major issue Heinkel had, was the engines overheating and subsequent fires, just like the US had with the B-29.


Yeah, the ironic problem was that, the fires were caused by the requirements for dive-bombing: It had to do with flexing of the engine nacelle (which resulted in a shorter nacelle shoved further back in the wing), a poorly designed oil pump, and other issues which I think had to do with the position of the electrical harnesses.


> The "glide bombing" doctrine hampered development


Agreed. They were fixated on the idea to the point of stupidity. It made sense for the Ju-87 to have this capability. One could even argue modifying a Do-17 to do it. It's getting a bit silly with the Ju-88, and by the He-177, it was fucking nuts.

What kind of bombsights did the Luftwaffe have from 1935 to 1941?


> Imagine the USAAC requiring the B-17 to have the same requirement and how long it would have taken Boeing to make it happen...


They would have needed serious creativity, and probably would have produced an overweight clunk that would have climbed considerably slower, and had a substantially shorter range that would have probably seen it useless in the intended role.


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## wuzak (Mar 18, 2020)

Zipper730 said:


> 1. Regarding the Hyper Engine: From what I remember, it would have been possible for the USAAC to have simply changed the contract terms for the V-1008 to the IV-1430 from single cylinder to mono-block to single-cylinder at any point in time. Would that have been a good idea to have done so?



Yes, of course they could. But that would involve more design and cost.

Also, there was never a V-1008 - that was always going to be the O-1008.




Zipper730 said:


> As for two valves per cylinder: The first development of four-valves per cylinder in a reciprocating engine was in 1916. I'm not sure when it first appeared in aircraft-engines, though it seemed to be there in the 1930's.



The 1912 Peugeot L76 Grand Prix car had dual overhead camshafts and 4 valves per cylinder. It won Grands Prix and also the 1913 Indianapolis 500.

That is often credited as being the first multi-valve engine, but I thought another was earlier, but I can't find that now.

Maybach and Daimler-Benz had 4V aero engines in 1916, and the Napier Lion appeared in 1918, also with 4V cylinder heads.
Bugatti's U-16 (two upright straight 8s connected by gears) had 3V heads in 1916. It was also built under licence in the US as the King-Bugatti.

The 1915 Hispano-Suiza 8 was the first aero engine to use a monoblock design. It was made under licence in many countries, including the UK and the US.

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## GrauGeist (Mar 18, 2020)

The Ju88 was actually an effective dive-bomber and used to good effect on the eastern front...one of many hats the Ju88 wore well.

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## Zipper730 (Mar 21, 2020)

S
 Shortround6
, 

 tomo pauk



wuzak said:


> Yes, of course they could. But that would involve more design and cost.
> 
> Also, there was never a V-1008 - that was always going to be the O-1008.


Actually, from what I remember the first design was 1008 cubic inches, and a V-inline. Would the money pooled up for the project have sunk us?


> The 1912 Peugeot L76 Grand Prix car had dual overhead camshafts and 4 valves per cylinder. It won Grands Prix and also the 1913 Indianapolis 500.


I didn't know that actually...


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## Zipper730 (Jun 12, 2020)

W
 wuzak


Actually, it did seem to have been a V at first...


> Sam Heron, head of development at Wright Field and a former colleague of Ricardo while Heron had been working at the Royal Aircraft Factory, Farnborough, started working on the problem with a single-cylinder test engine that he converted to liquid cooling, using a Liberty L-12 engine cylinder. He pushed the power to 480 psi Brake Mean Effective Pressure, and the coolant temperature to 300 °F (149 °C) before reaching the magic numbers. By 1932, the USAAC's encouraging efforts led the Army to sign a development contract with Continental Motors Company for the continued development of the engine design. The contract limited Continental's role to construction and testing, leaving the actual engineering development to the Army.
> Starting with the L-12-cylinder, they decreased the stroke from 7 in to 5 in in order to allow higher engine speeds, and then decreased the bore from 5 in to 4.62 in, creating the 84 in³ cylinder. This would be used in a V-12 engine of 1008 in³ displacement. They used the L-12's overhead camshaft to operate multiple valves of smaller size, which would improve charging and scavenging efficiency. Continental's first test engine, the single-cylinder Hyper No.1, first ran in 1933.
> They eventually determined that exhaust valves could run cooler when a hollow core filled with sodium is used — the sodium liquefies and considerably increases the heat transfer from the valve's head to its stem and then to the relatively cooler cylinder head where the liquid coolant picks it up.
> Liquid cooling systems at that time used plain water, which limited operating temperatures to about 180 °F (82 °C). The engineers proposed using ethylene glycol, which would allow temperatures up to 280 °F. At first they proposed using 100% glycol, but there was little improvement due to the lower specific heat of the glycol (about 2/3 that of water). They eventually determined that a 50/50 mixture (by volume) of water and glycol provided optimal heat removal.


While this comes from wikipedia *ducks*, it happens to match things I've heard said on this forum, though I can probably sift through this forum and find much of the same thing.

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## Admiral Beez (Jun 12, 2020)

wuzak said:


> This is loking a lot like an earlier thread
> 
> This is the way it should have been from the beginning....


Whenever I see a post like this I always assume we're being sent to a thread started by the poster. And yep, true enough.


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## Snowygrouch (Jun 12, 2020)

Ref the quote that 50/50 is the best coolant mix, thats totally dependant on operating conditions such as available pressurisation level
and the degree of cold weather the engine has to survive.

From a thermodynamics perspective there is absolutely nothing better than 100% water (possibly with some very small trace level of additives for surface tension reduction).

30% glycol that was used by many was basically just there as an anti-freeze and nothing more, as with high pressure cooling you dont need its higher boiling point.

50% glycol was needed if you a) Didnt want to run high system pressure or b) wanted to be able to leave the plane outside in the depths of winter (or both).

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## Zipper730 (Jun 12, 2020)

I was thinking about two things...

Blackburn Firebrand: How much performance could've been extracted out of the Blackburn Firebrand if it had a wing-design more like the Blackburn B.44?

Lockheed P-38: While the extreme modifications that NACA proposed for the P-38 were something that would have been too extreme from war production requirements. Would it have been too much to have added a tail-cone extension around either the time the P-38J came online (I saw a picture dated December 24, 1941, I'm not sure when tests were completed by the P-38J's came online in '43 if I recall)?


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## tomo pauk (Jun 12, 2020)

Zipper730 said:


> I was thinking about two things...
> 
> Blackburn Firebrand: How much performance could've been extracted out of the Blackburn Firebrand if it had a wing-design more like the Blackburn B.44?



Blackburn: make other people's designs and everyone is happy.



> Lockheed P-38: While the extreme modifications that NACA proposed for the P-38 were something that would have been too extreme from war production requirements. Would it have been too much to have added a tail-cone extension around either the time the P-38J came online (I saw a picture dated December 24, 1941, I'm not sure when tests were completed by the P-38J's came online in '43 if I recall)?



NACA's modifications for P-38s were not that extreme.


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## Zipper730 (Jun 12, 2020)

tomo pauk said:


> Blackburn: make other people's designs and everyone is happy.


I'm not sure I understand?


> NACA's modifications for P-38s were not that extreme.


Well they wanted them to extend the inboard wing chord, reposition the radiator in front of the wings, and add a tail-cone extension to the back of the gondola.

I was told this was something that wouldn't have been allowed at the time...


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## tomo pauk (Jun 12, 2020)

Zipper730 said:


> I'm not sure I understand?



The less Blackburn is allowed to design, the better for British war effort. Better have them making other people's designs.



> Well they wanted them to extend the inboard wing chord, reposition the radiator in front of the wings, and add a tail-cone extension to the back of the gondola.
> I was told this was something that ...



'It wouldn't have been allowed at the time' and 'the extreme modifications' are not synonyms. 
Do we have a correspondence between NACA and USAAF with regards to this?

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## Zipper730 (Jun 12, 2020)

tomo pauk said:


> The less Blackburn is allowed to design, the better for British war effort.


Okay, I gotcha. That said the wing-design for the B.44 was quite an improvement.


> 'It wouldn't have been allowed at the time' and 'the extreme modifications' are not synonyms.


True enough, but these were not small changes to the airframe. That said, the tail-cone seems fairly small


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## tomo pauk (Jun 12, 2020)

Zipper730 said:


> Okay, I gotcha. That said the wing-design for the B.44 was quite an improvement.



For a floatplane fighter - yes, B.44 as a whole was something else.



> True enough, but these were not small changes to the airframe. That said, the tail-cone seems fairly small



Wing was otherwise left unchaged, central pod received tailcone and a more slant windscreen. Same tail, fuel tanks, undercarriage, weapon suite.
The changes were much smaller than what Hawker did with Typhoon -> Tempest -> Sea Fury, or Bf 109E ->109F. Or, Re.2000 -> Re.2001 ->Re.2005. LaGG-3 -> La-5 -> La-7? Or Fw 190 -> Ta 152. Or the whole new aircraft the P-63 was against P-39, or P-51H vs. P-51D. 

A lot of P-38 potential was probably not realized due not having another source, like the P-51, F4U, A-20, B-17, Bf 109, Ju-87 or P-47 had. Any change will imply that production will drop to zero for several weeks, especially for the already complex aircraft the P-38 was.


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## Zipper730 (Jun 12, 2020)

tomo pauk said:


> For a floatplane fighter - yes, B.44 as a whole was something else.


Correct: Top speed was 360 mph. Regardless, the wings resemble the Tempest a little bit, though I don't know what the thickness/chord ratios are.


> The changes were much smaller than what Hawker did with Typhoon -> Tempest -> Sea Fury, or Bf 109E ->109F. Or, Re.2000 -> Re.2001 ->Re.2005. LaGG-3 -> La-5 -> La-7?


Good point, but the Tempest wasn't considered a variant of the Typhoon. It was essentially viewed as a new design entirely. The La-5 and La-7 were also viewed as different aircraft.


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## jmcalli2 (Dec 28, 2020)

Shortround6 said:


> I think they finally got one.
> The Updraft carb was probably a mistake in hindsight as any air intake on the bottom of the plane and 4-6 feet behind the propeller is going to catch all kinds of crud the prop blast/swirl kicks up, especially when the tail wheel comes up and the prop is only inches from the sod, dirt, sand, coral, etc, etc.
> 
> P-40s and Allison P-51s had the air intake on top and only inches behind the prop so their intake of self made grinding compound was much less, However formation take-offs needed care as your buddy's/wingman's plane could sure kick up enough crap to kill your engine.
> ...



Many aircraft had air filters designed in; P-61 (bottom of nacelle right behind the engine), B-24 (that box at the rear opening of each nacelle under the wing), P-51B onward (sides of the chin intake), P-38 (inside the main landing gear bays), P-40D onward (between spinner and exhaust stacks). I'm sure many more did too.

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## P-39 Expert (Dec 29, 2020)

jmcalli2 said:


> Many aircraft had air filters designed in; P-61 (bottom of nacelle right behind the engine), B-24 (that box at the rear opening of each nacelle under the wing), P-51B onward (sides of the chin intake), P-38 (inside the main landing gear bays), P-40D onward (between spinner and exhaust stacks). I'm sure many more did too.


I believe the P-63 had a built in air filter, adjustable for filtered or non-filtered air from a knob in the cockpit.

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## Zipper730 (Dec 29, 2020)

tomo pauk said:


> A lot of P-38 potential was probably not realized due not having another source, like the P-51, F4U, A-20, B-17, Bf 109, Ju-87 or P-47 had.


Just to circle back on this: Lockheed only had one factory making P-38's?

While on the matter of different ideas: I'm curious if they could have modified the XP-49 design requirement to include the modifications desired for the P-38?


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## P-39 Expert (Dec 29, 2020)

Zipper730 said:


> Just to circle back on this: Lockheed only had one factory making P-38's?
> 
> While on the matter of different ideas: I'm curious if they could have modified the XP-42 design requirement to include the modifications desired for the P-38?


?? P-42 was a P-36 with modified cowling and spinner.


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## tomo pauk (Dec 29, 2020)

Zipper730 said:


> Just to circle back on this: Lockheed only had one factory making P-38's?



It was a big factory  Though, it was supposed to make other aircraft, too. 
Once the XP-39 was discovered what it really was by NACA, I'd cancel it all together and have Bell making the P-38s under licence.



Zipper730 said:


> While on the matter of different ideas: I'm curious if they could have modified the XP-42 design requirement to include the modifications desired for the P-38?



I'm not sure that there was a relation between XP-42 and P-38.


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## GrauGeist (Dec 29, 2020)

Consolidated received a contract for 2,000 P-38s and manufactured 113 P-38L types at their Nashville (Tennessee) plant before war's end.
The serial numbers were #43-50234 through #43-50303.

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## jmcalli2 (Dec 29, 2020)

tomo pauk said:


> It was a big factory  Though, it was supposed to make other aircraft, too.
> Once the XP-39 was discovered what it really was by NACA, I'd cancel it all together and have Bell making the P-38s under licence.



Then Germany may have defeated the USSR! LOL


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## Conslaw (Dec 29, 2020)

tomo pauk said:


> It was a big factory  Though, it was supposed to make other aircraft, too.
> Once the XP-39 was discovered what it really was by NACA, I'd cancel it all together and have Bell making the P-38s under licence.
> 
> 
> ...



It not only was supposed to, it did. Lockheed Burbank plant B-1 made P-38 fighters and Hudson bombers. Plant A-1 built 2,750 B-17 bombers. Would Plant A-1 have been better utilized making P-38s? Well, I think you would have needed another plant making V-1710 engines too. AFAIK, all Allison V-1710 engines were built in Allison's Indianapolis Plant. Virtually all of the American high-volume radial engines had multiple plants building each one.

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## Zipper730 (Dec 30, 2020)

Uh... I meant XP-49. I corrected the earlier message.

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## P-39 Expert (Jan 3, 2021)

tomo pauk said:


> It was a big factory  Though, it was supposed to make other aircraft, too.
> Once the XP-39 was discovered what it really was by NACA, I'd cancel it all together and have Bell making the P-38s under licence.
> 
> 
> ...


What will you use for fighters in 1942? P-38 didn't get into combat until late '42.


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## tomo pauk (Jan 3, 2021)

P-39 Expert said:


> What will you use for fighters in 1942? P-38 didn't get into combat until late '42.



Wasn't the P-38 earlier in the combat than P-39?


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## P-39 Expert (Jan 3, 2021)

tomo pauk said:


> Wasn't the P-38 earlier in the combat than P-39?


I don't think so. P-39 was at Port Moresby in April '42. P-38 got into sustained combat in the Pacific and N. Africa in late '42. AAF would have ben hard pressed in '42 without the P-39.

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## GrauGeist (Jan 3, 2021)

P-39 Expert said:


> *What will you use for fighters in 1942? * P-38 didn't get into combat until late '42.


The Curtiss P-40...

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## P-39 Expert (Jan 3, 2021)

GrauGeist said:


> The Curtiss P-40...


A clean P-40E could not get to 20000' without climb falling below 1000fpm, the minimum for combat and speed topped out at 340mph at only 15000ft. Cold meat for any Zero or 109/190.


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## tomo pauk (Jan 3, 2021)

P-39 Expert said:


> I don't think so. P-39 was at Port Moresby in April '42. P-38 got into sustained combat in the Pacific and N. Africa in late '42. AAF would have ben hard pressed in '42 without the P-39.



They were hard pressed in 1942 in Pacific, but not in theaters against Germany, at least not until the Operation Torch.
1/4 or P-39s were lost en route from Australia to Port Moresby - so let's send the P-38s and P-40s there, not in the UK at 1st.
If AAF is lacking fighters inn 1942, there is that company in Inglewood that is begging for the USAAF attention during 1941.

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## P-39 Expert (Jan 3, 2021)

The P-39s lost en route from Australia to PM were due to weather and the fault of the fledgling AAF. Any P-38s and P-40s sent into that weather would have been lost.


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## XBe02Drvr (Jan 3, 2021)

tomo pauk said:


> Once the XP-39 was discovered what it really was by NACA, I'd cancel it all together and have Bell making the P-38s under licence.





P-39 Expert said:


> What will you use for fighters in 1942? P-38 didn't get into combat until late '42.


When the shortcomings of the P39 sank in, that big shiny new plant in Niagara built by Uncle Sam for Larry Bell could have been switched over to P40 production. This would have relieved Curtiss's overcrowded facility in downtown Buffalo, just down the road, as at that time, the new Bell plant was still tooling up. With no P39 the Soviets would have made better use of the P40 and never missed the P39. The P40 was a more versatile fighter and in short supply in 1941-42.
My dad worked at Bell Niagara late war, and said that in addition to P39s and P63s, they built sub assemblies for P38s. Oddly enough, 25 years later, I worked in the former Bell plant in Burlington VT, which by then was GE Aircraft Armament Division. Vulcans, minis, micros, turrets, pods, VADS, pintles, we made them all. And eventually (after my time), the 'Hog cannon and the CIWS. (the Sea-Whizz)

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## GrauGeist (Jan 3, 2021)

P-39 Expert said:


> A clean P-40E could not get to 20000' without climb falling below 1000fpm, the minimum for combat and speed topped out at 340mph at only 15000ft. Cold meat for any Zero or 109/190.


You do realize that the early P-40s saw action against Axis aircraft prior to 1942 and was able to hold it's own, right?
The bulk of engagements occurred at lower altitudes and the P-40 was proven to best the A6M and KI-43 as long as it maintained it's speed in a fight (i.e.: force the enemy to fight on the P-40's terms).

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## jmcalli2 (Jan 3, 2021)

tomo pauk said:


> Wasn't the P-38 earlier in the combat than P-39?



The P-39D fought over New Guinea in April 1942. By the end of 1942 P-39s had claimed 80 Japanese aircraft.
The first P-38 in action was the F-4, an unarmed photo recon version of the P-38E, in April 1942. The fighter version followed, shooting down their first Japanese aircraft in August 1942. That same month a P-38 based in Iceland shot down a Fw-200.

It wasn't so much which went into action first, it was production. The P-39 used one V-1710, the P-38 used two. In 1942 there were more P-39s than p-38s. In 1941, you could build P-39s faster than P-38s, so there were more P-39s available. 

A P-38 in the field required more mechanic time to maintain, more oil & fuel per mission, and twice the number of engine parts such as spark plugs compared to the P-39. To get fighters in place quickly in 1942, you used the single engined ones.

Overall, 9,588 P-39s and 3,303 P-63s, a total of 12,891 Cobras, were built during WWII. 
There were 10,037 P-38s built during WWII.


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## jmcalli2 (Jan 3, 2021)

GrauGeist said:


> The Curtiss P-40...



Not enough of them, and they were based on an older design, the P-36.


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## jmcalli2 (Jan 3, 2021)

GrauGeist said:


> You do realize that the early P-40s saw action against Axis aircraft prior to 1942 and was able to hold it's own, right?
> The bulk of engagements occurred at lower altitudes and the P-40 was proven to best the A6M and KI-43 as long as it maintained it's speed in a fight (i.e.: force the enemy to fight on the P-40's terms).



I believe that the P-40s with the AVG didn't fight Zeros, they fought Oscars and Nates. Zeros were naval fighters, and the AVG was up against Japanese Army units. Also, the AVG and Chinese used P-40s, P-66s, P-43s and other aircraft in addition to P-40s. Same tactics applied though; Chenault developed them by, among other things, learning from Soviet pilots who had fought the Japanese.
Interesting that the tactics didn't get out from the AVG to the AAF and USN/USMC; they had to reinvent these tactics for themselves. The P-39s in New Guinea suffered for it.


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## GrauGeist (Jan 3, 2021)

jmcalli2 said:


> Not enough of them, and they were based on an older design, the P-36.


That's pretty much common knowledge - plus the P-36 and P-40 fought alongside each other at Pearl Harbor.


jmcalli2 said:


> I believe that the P-40s with the AVG didn't fight Zeros, they fought Oscars and Nates. Zeros were naval fighters, and the AVG was up against Japanese Army units.


You apparently missed where I stated A6M AND KI-43 in my post, which did not have anything to do with the AVG specifically.
The P-40 did fight both, the A6M being prevelant in the defence of Australia and the Solomons/New Guinea campaigns early on.

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## tomo pauk (Jan 3, 2021)

jmcalli2 said:


> The P-39D fought over New Guinea in April 1942. By the end of 1942 P-39s had claimed 80 Japanese aircraft.
> The first P-38 in action was the F-4, an unarmed photo recon version of the P-38E, in April 1942. The fighter version followed, shooting down their first Japanese aircraft in August 1942. That same month a P-38 based in Iceland shot down a Fw-200.



With Bell making P-38s instead the P-39s, there can be more of P-38s than historically. They also have far better range & radius, a thing that was a crucial asset in Pacific; better turn of spedd and climb from 10000 ft on are another nods for the P-38.



> It wasn't so much which went into action first, it was production. The P-39 used one V-1710, the P-38 used two. In 1942 there were more P-39s than p-38s. In 1941, you could build P-39s faster than P-38s, so there were more P-39s available.
> 
> A P-38 in the field required more mechanic time to maintain, more oil & fuel per mission, and twice the number of engine parts such as spark plugs compared to the P-39. To get fighters in place quickly in 1942, you used the single engined ones.



P-38 could do the missions P-39 could do, while vice-versa is not true. P-39 is incapable of escorting the bombers beyond 150-200 miles, the P-38 can do more than twice of that. P-38 can intercept Japanese flying at 17000 ft and above, P-39 not so well.
As above - Bell making P-38s means there is more P-38s to come by, even if it might be 4:9 ratio in favor of P-39.


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## jmcalli2 (Jan 3, 2021)

GrauGeist said:


> That's pretty much common knowledge - plus the P-36 and P-40 fought alongside each other at Pearl Harbor.
> 
> You apparently missed where I stated A6M AND KI-43 in my post, which did not have anything to do with the AVG specifically.
> The P-40 did fight both, the A6M being prevelant in the defence of Australia and the Solomons/New Guinea campaigns early on.



I blame my fat fingers.

LOL

Sorry!


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## XBe02Drvr (Jan 3, 2021)

jmcalli2 said:


> Not enough of them, and they were based on an older design, the P-36.


There could have been, if Bell Niagara had been tooled for P40 production in place of P39. Alternate assembly lines could have allowed newer or modified models to go on line without pausing production to retool the one and only production facility. E's and perhaps F's sooner and in greater quantities.

PS: We used to fly to Buffalo and to Niagara, and I've seen both plants, as well as what used to be Curtiss's airport facility (which didn't yet exist at the time frame in question).
The Bell Niagara plant was huge, though when I saw it was a Westinghouse plant and an industrial park.


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## jmcalli2 (Jan 3, 2021)

tomo pauk said:


> With Bell making P-38s instead the P-39s, there can be more of P-38s than historically. They also have far better range & radius, a thing that was a crucial asset in Pacific; better turn of spedd and climb from 10000 ft on are another nods for the P-38.
> 
> 
> 
> ...



That is true.

However, if you look at production, in 1941 the USAAF accepted 205 P-38s and 926 P-39s for the entire year.
Through the end of April 1942 they accepted 325 more P-38s and 486 P-39s.
That gives you 530 P-38s and 1412 P-39s for a total of 1942 (!) by the end of April 1942.
You just were not going to ramp up P-38 production any faster.
If you used Bell to make P-38s, then you'd at best make half as many P-38s as P-39s were built there due to engine supply. That means you've have 1236 fighters instead of 1942.
I don't see having 706 fewer fighters as being an advantage.

In case I botched the math, you can see the production figures here:

U.S.A.A.F. Fighter Monthly Acceptances (1940-1946)

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## tomo pauk (Jan 3, 2021)

jmcalli2 said:


> That is true.
> 
> However, if you look at production, in 1941 the USAAF accepted 205 P-38s and 926 P-39s for the entire year.
> Through the end of April 1942 they accepted 325 more P-38s and 486 P-39s.
> ...



I'm sure your math is correct; the production of P-38s at Lockheed was not something they will be able to brag about until well into 1942.
Striving just to have as many fighters as possible while not looking at what the fighters are capable for might be a bad math for the USAAC in 1942, however. The P-39, as a fighter that was ill able to cover the area 200-300-400 miles away from the base, was heavily criticized by Gen Kenney.


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## P-39 Expert (Jan 3, 2021)

tomo pauk said:


> With Bell making P-38s instead the P-39s, there can be more of P-38s than historically. They also have far better range & radius, a thing that was a crucial asset in Pacific; better turn of spedd and climb from 10000 ft on are another nods for the P-38.
> 
> 
> 
> ...


Here's a performance graph of the P-39K (basically same as P-39D), A6M2 Zero in red and P-40E in green. Blue is P-39 climb at 3000rpm. All straight from wwiiaircraftperformance.

The P-40E is barely faster than the Zero at 15000ft but falls off rapidly above that and will not climb to 20000ft and maintain 1000fpm climb rate. P-40E is deficient to P39 in all respects and barely as fast as the Zero. This is mid '42 and P-38 Lightning is not available yet.


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## tomo pauk (Jan 3, 2021)

P-39 Expert said:


> Here's a performance graph of the P-39K (basically same as P-39D), A6M2 Zero in red and P-40E in green. Blue is P-39 climb at 3000rpm. All straight from wwiiaircraftperformance.
> 
> The P-40E is barely faster than the Zero at 15000ft but falls off rapidly above that and will not climb to 20000ft and maintain 1000fpm climb rate. P-40E is deficient to P39 in all respects and barely as fast as the Zero. This is mid '42 and P-38 Lightning is not available yet.



Let's pick the least capable P-40 and the least capable Zero, while picking the most capable P-39 and draw conclusions? Sorry - no. 
Lighting is available already in 1941.


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## P-39 Expert (Jan 3, 2021)

tomo pauk said:


> Let's pick the least capable P-40 and the least capable Zero, while picking the most capable P-39 and draw conclusions? Sorry - no.
> Lighting is available already in 1941.


Those were the versions available in mid 1942. By October the improved P-39s and P-40s with the 9.6 supercharged engines would be in production but the P-40 always lagged behind the P-39 in performance since they were about 600lbs heavier. The much improved Merlin P-40F had about the exact same performance as that P-39K on the graph. And the K model was about the same as the D model. And these were the 7650lb versions which could have been significantly lighter. 

In the entire year of 1941 there were only 205 lightnings produced including only 36 P-38Ds and maybe 60 P-38Es. 115 E models were produced between Sept '41 and April '42. The first real combat capable P-38s were the F & G models. Lightnings were just not available for combat yet.


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## jmcalli2 (Jan 3, 2021)

tomo pauk said:


> I'm sure your math is correct; the production of P-38s at Lockheed was not something they will be able to brag about until well into 1942.
> Striving just to have as many fighters as possible while not looking at what the fighters are capable for might be a bad math for the USAAC in 1942, however. The P-39, as a fighter that was ill able to cover the area 200-300-400 miles away from the base, was heavily criticized by Gen Kenney.



But, it held the Japanese at bay; it accomplished what it needed to.
The P-40 was the most numerous AAF fighter at the time, but was slower, climbed worse, and did not turn as well as the P-39. Had there been P-40s in New Guinea instead of P-39s, nothing would have changed.

As a mentor once told me, sometimes 'just good enough' is good enough.

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## tomo pauk (Jan 3, 2021)

jmcalli2 said:


> ...
> Had there been P-40s in New Guinea instead of P-39s, nothing would have changed.
> ...



Thank you.

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## GrauGeist (Jan 3, 2021)

jmcalli2 said:


> Had there been P-40s in New Guinea instead of P-39s, nothing would have changed.


Just a head's up: there were P-40s in New Guinea and northern Australia, both USAAF and RAAF. They had been diverted when the Japanese attacked the Philippines.
They were reinforced by new P-40s as well as new P-39s (delivered 25 April 1942).


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## jmcalli2 (Jan 3, 2021)

tomo pauk said:


> Thank you.



Some thoughts on that:

The P-39s did not have what the AVG did; an 'early warning system' of observers warning them of incoming attacks.
They often had 10 minutes or less to get in their planes and climb to 20,000 ft to intercept. Too often they were bounced on the vulnerable way up.

The USAAF planned for combat put to 15,000 ft. The rest of the world planned on 20,000 ft.
The turbocharged P-43 had capabilities well above 20,000 ft, yet AAF testing, http://www.wwiiaircraftperformance.org/P-43/P-43_Official_Performance_Summary.jpg , tended to stop at 15,000 ft.

In December of 1941 the USAAF was in the process of replacing their too few P-35s and P-36s with P-40s, P-39s, and P-38s while developing P-47s and P-51s. 1942 was the year of gaining experience while building up forces. 
All that was required of the P-39s and P-40s was to be good enough.
They were good enough.

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## wuzak (Jan 3, 2021)

jmcalli2 said:


> Not enough of them, and they were based on an older design, the P-36.



Weren't there many more P-40s available than P-39s at the time?


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## jmcalli2 (Jan 3, 2021)

wuzak said:


> Weren't there many more P-40s available than P-39s at the time?



U.S.A.A.F. Fighter Monthly Acceptances (1940-1946)

4380 P-40s were accepted by the USAAF from 1940 through the end of April 1942.
Even though the P-40 had a seven month 'head start' over the P-39 and about a year on the P-38, Curtiss did a very good job of cranking them out.
But by 1943 Bell was producing more P-39s than Curtiss was P-40s. 
In fact, in 1943 Bell cranked out more P-39s @ 4,947, than P-40s @ 4,258, P-47s @ 4,428, P-38s @ 2,213, and P-51s @ 1,710.
That's 17,556 solid fighters in 1943 alone, not including 6,065 USN/USMC fighters.
Germany produced 10,059 fighters in 1943.
Japan produced 7,147 fighters in 1943.
Germany and Japan were not producing meaningful numbers of heavy bombers in 1943. The US produced over 9,500 that year.
US fighter production surged from 23,000+ in 1943 to over 38,000 in 1944, the year P-40 production stopped.

It was as much a numbers war as a qualitative one.

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## GrauGeist (Jan 3, 2021)

wuzak said:


> Weren't there many more P-40s available than P-39s at the time?


Between January 1941 and December 1941, the USAAC took delivery of 131 P-40Bs, 193 P-40Cs and 22 P-40Ds.
This doesn't include the first type, P-40 (no "A") that the Air Corps accepted before the production was deferred to fill the French order.
A number of these P-40s listed above, were lost during the Japanese attacks at Pearl Harbor, the Philippines and the sinking of the USS Langley (CV-1) in January 1942, which saw the loss of 64 P-40s: 32 "fly off" and 27 crated.


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## nuuumannn (Jan 3, 2021)

jmcalli2 said:


> while developing P-47s and *P-51s*.



Just a wee note, by December 1941, all Mustang production was for the RAF. The Mustang was at that time ostensibly a 'British' aircraft, although two examples had gone to Wright Patterson for evaluation in July 1941. The USAAC/AAF had not shown any interest in it initially, but the Army ordered 150, simply designated P-51s (which became Mustang Ias and Mustang IIs) in July 1941 under Lend Lease for the RAF, but it wasn't until early/mid 1942 that the USAAF looked to the type, as an attack aircraft, not a fighter, for its own ranks.

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## Milosh (Jan 3, 2021)

Why did it take so long for the AAF to look at the Mustang?


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## GrauGeist (Jan 3, 2021)

Milosh said:


> Why did it take so long for the AAF to look at the Mustang?


At the time, the Army had fighter contracts for the P-40, P-38 and P-39.
With the Mustang being developed for Britain, the Army was not particularly involved until they evaluated it.

And to touch on an earlier comment about Curtiss production: Bell may have delivered more P-39s to the USAAF than Curtiss, but that's not taking into account that Curtiss (at the time) was delivering more P-40s to Britain than the U.S. (which is the reason the Mustang came into being).

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## nuuumannn (Jan 3, 2021)

Milosh said:


> Why did it take so long for the AAF to look at the Mustang?



Because it was designed and built for the British and contractually, RAF requirements had to be met first. As Dave points out, the AAF already had fighters under order when the Mustang entered the picture.

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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> Interesting that the tactics didn't get out from the AVG to the AAF and USN/USMC; they had to reinvent these tactics for themselves.


They did get out, Chenault saw to that. His nemesises from Air Corps days saw to it that they they were debunked as "Buck Rogers stuff" and didn't get disseminated.


tomo pauk said:


> Lighting is available already in 1941.


Maybe stateside, and for testing and training, but not where it counts; battle-ready in the theater of operations. It's a long way from official acceptance on the manufacturer's ramp to the first combat sortie.

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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> The USAAF planned for combat put to 15,000 ft. The rest of the world planned on 20,000 ft.
> The turbocharged P-43 had capabilities well above 20,000 ft, yet AAF testing, http://www.wwiiaircraftperformance.org/P-43/P-43_Official_Performance_Summary.jpg , tended to stop at 15,000 ft.


"Big Army", who held the purse strings for USAAF, still tended to think of pursuit aviation as a battlefield tool, not a defensive or strategic asset.


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## XBe02Drvr (Jan 4, 2021)

GrauGeist said:


> the P-40 was proven to best the A6M and KI-43 as long as it maintained it's speed in a fight (i.e.: force the enemy to fight on the P-40's terms).


And the P40's controls were better balanced and easier to handle at higher speeds than the Japanese fighters. Something that doesn't show up on performance charts, but makes a big difference in combat.

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## P-39 Expert (Jan 4, 2021)

jmcalli2 said:


> Some thoughts on that:
> 
> The P-39s did not have what the AVG did; an 'early warning system' of observers warning them of incoming attacks.
> They often had 10 minutes or less to get in their planes and climb to 20,000 ft to intercept. Too often they were bounced on the vulnerable way up.
> ...


True on the early warning system of observers, sometimes called coast watchers. They were usually people who lived in the area, farmers, etc. Hazardous as they were hunted by the Japanese. 

Australian radar was just too far away to do much good. Radar was installed at Milne Bay in August and at Port Moresby in September, but from April until August/September they were blind for incoming raids. And those raids were coming from Lae less then 200 miles away. Either fly patrols with the two squadrons available or wait on the ground. Tough duty.

I've always maintained that the P-39 would have been much more effective much higher up had it weighed less, and the weight reduction could have been accomplished at forward bases.

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## P-39 Expert (Jan 4, 2021)

nuuumannn said:


> Just a wee note, by December 1941, all Mustang production was for the RAF. The Mustang was at that time ostensibly a 'British' aircraft, although two examples had gone to Wright Patterson for evaluation in July 1941. The USAAC/AAF had not shown any interest in it initially, but the Army ordered 150, simply designated P-51s (which became Mustang Ias and Mustang IIs) in July 1941 under Lend Lease for the RAF, but it wasn't until early/mid 1942 that the USAAF looked to the type, as an attack aircraft, not a fighter, for its own ranks.


Didn't some of the early Mustangs have four 20mm cannons? Were they belt-fed, and how many rounds did they carry?


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## jmcalli2 (Jan 4, 2021)

GrauGeist said:


> At the time, the Army had fighter contracts for the P-40, P-38 and P-39.
> With the Mustang being developed for Britain, the Army was not particularly involved until they evaluated it.
> 
> And to touch on an earlier comment about Curtiss production: Bell may have delivered more P-39s to the USAAF than Curtiss, but that's not taking into account that Curtiss (at the time) was delivering more P-40s to Britain than the U.S. (which is the reason the Mustang came into being).




Weren't P-40s going to Britain Lend Lease planes, officially accepted by the US? Certainly that holds true for the P-39s & P-63s, most of which ended up in the USSR.


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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> Weren't P-40s going to Britain Lend Lease planes, officially accepted by the US? Certainly that holds true for the P-39s & P-63s, most of which ended up in the USSR.


Once Lend-Lease was approved as official policy, planes passed through US ownership enroute to allies. Prior to that, they were direct purchase export products and belonged to their purchasers. This happened in the middle of production of several types: Boston, Harvard, Maryland, Catalina, Hawk 75, Tomahawk, Airacobra, to name a few.

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## jmcalli2 (Jan 4, 2021)

P-39 Expert said:


> True on the early warning system of observers, sometimes called coast watchers. They were usually people who lived in the area, farmers, etc. Hazardous as they were hunted by the Japanese.
> 
> Australian radar was just too far away to do much good. Radar was installed at Milne Bay in August and at Port Moresby in September, but from April until August/September they were blind for incoming raids. And those raids were coming from Lae less then 200 miles away. Either fly patrols with the two squadrons available or wait on the ground. Tough duty.
> 
> I've always maintained that the P-39 would have been much more effective much higher up had it weighed less, and the weight reduction could have been accomplished at forward bases.



Once the AAF had decided the P-39 was for ground attack, they put a LOT of armor into it. Some models had almost four times the armor of a Spitfire:

The WWII Fighter Gun Debate: Fighter Armour

The other issue with the AAF during the first two years of the war was their babying of the V-1710. While evaluating the Mustang I the RAF found they could use it at much higher boost levels than the manuals allowed; in fact, the throttles were locked at 44" Hg. The RAF found they could operate the Allisons at up to 72" Hg for 20 minutes without harm to the engine:

E-GEH-16. near the bottom of the page.

Gotta wonder what the P-39 would have done with the extra boost.


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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> Gotta wonder what the P-39 would have done with the extra boost.


In the icy steppes of Russia, plenty; in the steaming jungles of New Guinea, probably not so much.


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## jmcalli2 (Jan 4, 2021)

tomo pauk said:


> Let's pick the least capable P-40 and the least capable Zero, while picking the most capable P-39 and draw conclusions? Sorry - no.
> Lighting is available already in 1941.



Again, 205 P-38s were accepted by the AAF in ALL of 1941.
In the beginning of January 1941 the AAF had exactly one P-38. By the end of the month they had two.
They had to produce the planes, deploy them and figure out & deploy the logistics to support them, develop a training program and train the pilots.

U.S.A.A.F. Fighter Monthly Acceptances (1940-1946)

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## jmcalli2 (Jan 4, 2021)

XBe02Drvr said:


> "Big Army", who held the purse strings for USAAF, still tended to think of pursuit aviation as a battlefield tool, not a defensive or strategic asset.



Which, interestingly, was how the USSR used the P-39.
And they had great success with it.

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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> Which, interestingly, was how the USSR used the P-39.
> And they had great success with it.


But as a local air superiority weapon, not a tank buster or a troop attacker.

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## P-39 Expert (Jan 4, 2021)

jmcalli2 said:


> Once the AAF had decided the P-39 was for ground attack, they put a LOT of armor into it. Some models had almost four times the armor of a Spitfire:
> 
> The WWII Fighter Gun Debate: Fighter Armour
> 
> ...


Extra boost would only be available up to the critical altitude of around 14000' with ram.

Interesting how the Brits required 120kg of armor on the P-400 (P-39) but only 33kg on their Spitfire.

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## jmcalli2 (Jan 4, 2021)

XBe02Drvr said:


> Once Lend-Lease was approved as official policy, planes passed through US ownership enroute to allies. Prior to that, they were direct purchase export products and belonged to their purchasers. This happened in the middle of production of several types: Boston, Harvard, Maryland, Catalina, Hawk 75, Tomahawk, Airacobra, to name a few.



The production numbers in total match the entire production run for each model. It's down at the bottom of the column for each fighter.
For example, the 13,738 P-40s matches total production cited in Angelucci and Matricardi 1978, p. 48

U.S.A.A.F. Fighter Monthly Acceptances (1940-1946)

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## jmcalli2 (Jan 4, 2021)

XBe02Drvr said:


> But as a local air superiority weapon, not a tank buster or a troop attacker.



The P-38 was never a tank buster. The 37mm M4 was designed as a bomber killer. While there was an AP shell produced, that shell was never provided to the USSR. They only got the HE shells.
You don't get to be the American made fighter that shoots down the most enemy planes in WWII by firing at tanks.


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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> The production numbers in total match the entire production run for each model.


Betcha those totals were compiled "for the record" *after* Lend-Lease became official.


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## jmcalli2 (Jan 4, 2021)

P-39 Expert said:


> Extra boost would only be available up to the critical altitude of around 14000' with ram.
> 
> Interesting how the Brits required 120kg of armor on the P-400 (P-39) but only 33kg on their Spitfire.



Reading those reports can give a lot of "peripheral" information that makes you go, "Hmm!"

Like, why did the AAF stop testing maximum speed on the P-43 at 15,000 feet when it was supposed to operate from 20,000-25,000 feet? Hmm.


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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> The P-38 was never a tank buster. The 37mm M4 was designed as a bomber killer. While there was an AP shell produced, that shell was never provided to the USSR. They only got the HE shells.
> You don't get to be the American made fighter that shoots down the most enemy planes in WWII by firing at tanks.


We're on the same page here. My comment was a reflexive response to the common myth that the P39 was intended for attack work. I see now that was not your intended implication.

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## Milosh (Jan 4, 2021)

jmcalli2 said:


> The production numbers in total match the entire production run for each model. It's down at the bottom of the column for each fighter.
> For example, the 13,738 P-40s matches total production cited in Angelucci and Matricardi 1978, p. 48
> 
> U.S.A.A.F. Fighter Monthly Acceptances (1940-1946)



Looks like a copy from, army_air_forces_statistical_digest_ww2_1945.pdf (91stbombgroup.com)


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## XBe02Drvr (Jan 4, 2021)

jmcalli2 said:


> Like, why did the AAF stop testing maximum speed on the P-43 at 15,000 feet when it was supposed to operate from 20,000-25,000 feet? Hmm


Ref post #692. "Who cares about the stratosphere? It's troops on the ground need protection!"

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## XBe02Drvr (Jan 4, 2021)

P-39 Expert said:


> Extra boost would only be available up to the critical altitude of around 14000' with ram.


And that density altitude would be at a much lower MSL physical altitude in a tropical climate. Taking off at sea level on a summer's day in Key West, we could be starting off with a density altitude of 1,000-1500 feet, and that's only subtropical. A Cessna 150 with two lanky guys aboard and the magneto timing adjusted for 100LL has a climb performance slightly shy of a lead sled and feels like a solar heated phone booth full of octopi.
With the standard cruise prop, that little 200 cu in, 100 HP, 80 octane engine running on 100LL can only muster 87 HP at Vy. Thank God for thermals!

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## jmcalli2 (Jan 4, 2021)

XBe02Drvr said:


> We're on the same page here. My comment was a reflexive response to the common myth that the P39 was intended for attack work. I see now that was not your intended implication.



I understood, just reinforcing you.

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## jmcalli2 (Jan 4, 2021)

Milosh said:


> Looks like a copy from, army_air_forces_statistical_digest_ww2_1945.pdf (91stbombgroup.com)



Could be. At the top of the page are links to the data in a spread sheet format which may be useful. I didn't check to see if the links were still active though.


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## P-39 Expert (Jan 4, 2021)

XBe02Drvr said:


> And that density altitude would be at a much lower MSL physical altitude in a tropical climate. Taking off at sea level on a summer's day in Key West, we could be starting off with a density altitude of 1,000-1500 feet, and that's only subtropical. A Cessna 150 with two lanky guys aboard and the magneto timing adjusted for 100LL has a climb performance slightly shy of a lead sled and feels like a solar heated phone booth full of octopi.


Yes and your opponent would be flying in the same atmosphere.


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## swampyankee (Jan 4, 2021)

P-39 Expert said:


> Extra boost would only be available up to the critical altitude of around 14000' with ram.
> 
> Interesting how the Brits required 120kg of armor on the P-400 (P-39) but only 33kg on their Spitfire.



How did one need to arrange the armor to get comparable protection?


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## XBe02Drvr (Jan 4, 2021)

P-39 Expert said:


> Yes and your opponent would be flying in the same atmosphere.


Yes, but with a significant supercharger advantage and a super lightweight and high lift airframe. Superior power giving superior thrust/weight, and superior L/D at altitude.


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## jmcalli2 (Jan 4, 2021)

swampyankee said:


> How did one need to arrange the armor to get comparable protection?


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## wuzak (Jan 4, 2021)

P-39 Expert said:


> Extra boost would only be available up to the critical altitude of around 14000' with ram.



Not only that, the full extra boost of 72" MAP was only available at sea level, reducing with altitude until the standard boost was reached at critical altitude.


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## GrauGeist (Jan 4, 2021)

swampyankee said:


> How did one need to arrange the armor to get comparable protection?


Easy, really. To improve performance, simply remove the front, rear and pilot plates as well as the safety glass. Push the aircraft into the ocean and get a P-38...

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## Stig1207 (Jan 5, 2021)

P-39 Expert said:


> True on the early warning system of observers, sometimes called coast watchers. They were usually people who lived in the area, farmers, etc. Hazardous as they were hunted by the Japanese.
> 
> Australian radar was just too far away to do much good. Radar was installed at Milne Bay in August and at Port Moresby in September, but from April until August/September they were blind for incoming raids. And those raids were coming from Lae less then 200 miles away. Either fly patrols with the two squadrons available or wait on the ground. Tough duty.
> 
> I've always maintained that the P-39 would have been much more effective much higher up had it weighed less, and the weight reduction could have been accomplished at forward bases.



Huh? It was the coast watchers that provided early warning of incoming Japanese raids, so the P-39's were up at altitude waiting for the raiders. It was the Japanese that had no early warning system and were blind to incoming raids over New Guinea in 1942.



> You don't get to be the American made fighter that shoots down the most enemy planes in WWII by firing at tanks.



It might be the American made fighter that *claims *the most enemy planes shot down in WWII, but it is certainly not the one that *actually *shot down the most enemy planes.


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## GrauGeist (Jan 5, 2021)

Stig1207 said:


> It might be the American made fighter that *claims *the most enemy planes shot down in WWII, but it is certainly not the one that *actually *shot down the most enemy planes.


Please, enlighten us on which aircraft type (I assume Allied) downed the most enemy aircraft, then.


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## buffnut453 (Jan 5, 2021)

Oh no!!! They're talking about removing my armour plate and reducing my weight again!!!! Do I really look that overweight? All this discussion about my weight and ability to climb is affecting my ego. Time for another session with my therapist. MAKE THE BAD MEN STOP!!!!!!!

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## XBe02Drvr (Jan 5, 2021)

Stig1207 said:


> It might be the American made fighter that *claims *the most enemy planes shot down in WWII, but it is certainly not the one that *actually *shot down the most enemy planes.


Are you implying that our esteemed allies on the eastern front would stoop so low as to over-claim air-to-air kills? Tsk, tsk, come on now, be nice!

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## P-39 Expert (Jan 5, 2021)

jmcalli2 said:


> View attachment 607593


Delete those 100lb plates right behind the propeller. Plane would need reballasting by moving the radio up from the tail cone to above the engine right behind the pilot, or some other means. After all, Bell was able to balance the plane with both the 37mm cannon and the 20mm cannon which weighed 140lbs less. Other WWII fighters didn't have armor for their nose reduction gears.


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## jmcalli2 (Jan 5, 2021)

Stig1207 said:


> Huh? It was the coast watchers that provided early warning of incoming Japanese raids, so the P-39's were up at altitude waiting for the raiders. It was the Japanese that had no early warning system and were blind to incoming raids over New Guinea in 1942.(



Not in 1942.


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## jmcalli2 (Jan 5, 2021)

P-39 Expert said:


> Delete those 100lb plates right behind the propeller. Plane would need reballasting by moving the radio up from the tail cone to above the engine right behind the pilot, or some other means. After all, Bell was able to balance the plane with both the 37mm cannon and the 20mm cannon which weighed 140lbs less. Other WWII fighters didn't have armor for their nose reduction gears.



To be honest, and using 20/20 hind sight, I'd drop the armor behind the oil tank and replace the 37mm with another .50cal. Save another 200lbs.


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## XBe02Drvr (Jan 5, 2021)

P-39 Expert said:


> Other WWII fighters didn't have armor for their nose reduction gears.


Of course not. Their reduction gears were integral to the engine and not vulnerable from the rear quarter unless the entire engine was penetrated. A hit from the front would likewise take out the engine, likely allowing pilot survival.
Propeller driveshafts are notorious for having balance and torsional flexing problems leading to fatigue failures. A piston engine doesn't rotate smoothly, but in a series of impulses, like a hammer drill. Now connect that to a smoothly rotating propeller via a rotary tuning fork subject to 1100 HP worth of torque impulses at 3,000 RPM which passes right under the pilot's seat. Now imagine at full throttle this contraption takes a hit to the reduction gearbox, which either decouples the propeller, instantly way overreving and blowing the engine, or seizes the gearbox, snapping the shaft with the same result. Given that the engine is practically in the cockpit, and emergency egress is awkward at best, what does that say for survivability? Armor that gearbox, but "don't give me a P39!"

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## pinsog (Jan 5, 2021)

jmcalli2 said:


> Reading those reports can give a lot of "peripheral" information that makes you go, "Hmm!"
> 
> Like, why did the AAF stop testing maximum speed on the P-43 at 15,000 feet when it was supposed to operate from 20,000-25,000 feet? Hmm.







top speed of the P43 was listed at 352-356 at 25,000 feet. I wish they had given time to climb up to 30,000 feet along with top speed at 30,000 feet. I like the P43 myself. If it had fuel tanks (just regular tanks that didn’t leak, not to mention self sealing) and a bit of pilot armor I think it would have done well against the Zero and KI43 in the Pacific using hit and run tactics.

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## jmcalli2 (Jan 5, 2021)

pinsog said:


> View attachment 607674
> 
> top speed of the P43 was listed at 352-356 at 25,000 feet. I wish they had given time to climb up to 30,000 feet along with top speed at 30,000 feet. I like the P43 myself. If it had fuel tanks (just regular tanks that didn’t leak, not to mention self sealing) and a bit of pilot armor I think it would have done well against the Zero and KI43 in the Pacific using hit and run tactics.



It's hard to tell if the graph was testing or extrapolation neither the graph nor the report have dates on them.
The report only gives 339 at 15,000' as the max speed.
Another mystery...


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## swampyankee (Jan 5, 2021)

P-39 Expert said:


> Delete those 100lb plates right behind the propeller. Plane would need reballasting by moving the radio up from the tail cone to above the engine right behind the pilot, or some other means. After all, Bell was able to balance the plane with both the 37mm cannon and the 20mm cannon which weighed 140lbs less. Other WWII fighters didn't have armor for their nose reduction gears.



Other planes had engines in front of the pilot. Perhaps that’s a reason for the armor there


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## jmcalli2 (Jan 5, 2021)

swampyankee said:


> Other planes had engines in front of the pilot. Perhaps that’s a reason for the armor there



Their was also armor to protect the pilot:


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## BiffF15 (Jan 5, 2021)

P-39 Expert said:


> Delete those 100lb plates right behind the propeller. Plane would need reballasting by moving the radio up from the tail cone to above the engine right behind the pilot, or some other means. After all, Bell was able to balance the plane with both the 37mm cannon and the 20mm cannon which weighed 140lbs less. Other WWII fighters didn't have armor for their nose reduction gears.



I thought the radio was so far aft to prevent interference from the engine?

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## jmcalli2 (Jan 5, 2021)

BiffF15 said:


> I thought the radio was so far aft to prevent interference from the engine?



I think some P-39s and P-63s had some of their radio equipment behind the pilot's head;

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## Stig1207 (Jan 5, 2021)

GrauGeist said:


> Please, enlighten us on which aircraft type (I assume Allied) downed the most enemy aircraft, then.



For an American made fighter it would have to be the P-51.



> Are you implying that our esteemed allies on the eastern front would stoop so low as to over-claim air-to-air kills? Tsk, tsk, come on now, be nice!



Overclaiming was hardly unique to either the Soviets or to the Eastern Front.


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## Stig1207 (Jan 5, 2021)

jmcalli2 said:


> Not in 1942.



In 1942 over New Guinea.


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## XBe02Drvr (Jan 6, 2021)

jmcalli2 said:


>


And there it is. The Bell plant at IAG. Used to do overnights in IAG.

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## XBe02Drvr (Jan 6, 2021)

Stig1207 said:


> For an American made fighter it would have to be the P-51.


What's your data source? I always heard the Hellcat and the Spitfire held the top spots.


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## XBe02Drvr (Jan 6, 2021)

BiffF15 said:


> I thought the radio was so far aft to prevent interference from the engine?





jmcalli2 said:


> I think some P-39s and P-63s had some of their radio equipment behind the pilot's head;


EMI shielding, like everything else evolves over time. Metal jacketed resistor spark plugs, shielded ignition harnesses, generator noise filters, and grounded electronic chassis enclosures each play their part.

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## tyrodtom (Jan 6, 2021)

That


Stig1207 said:


> For an American made fighter it would have to be the P-51.
> 
> 
> 
> Overclaiming was hardly unique to either the Soviets or to the Eastern Front.





jmcalli2 said:


> I think some P-39s and P-63s had some of their radio equipment behind the pilot's head;
> View attachment 607742
> View attachment 607743
> View attachment 607744


That's identified as the IFF in some cutaways.
In the WW2 era radios were usually two different parts, receiver and transmitter, one was much heavier and delicate than the other.
That has the receiver mounted right over the engine, I think that's actually the transmitter, or the IFF.
The receiver were usually mounted on bungee cords, etc., and as far from the engine as they could be located.
I may have the receiver and transmitter confused as to which was heavier, and delicate, but in most WW2 aircraft they were separate assemblies, and sometimes mounted in separate locations.

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## P-39 Expert (Jan 6, 2021)

XBe02Drvr said:


> Of course not. Their reduction gears were integral to the engine and not vulnerable from the rear quarter unless the entire engine was penetrated. A hit from the front would likewise take out the engine, likely allowing pilot survival.
> Propeller driveshafts are notorious for having balance and torsional flexing problems leading to fatigue failures. A piston engine doesn't rotate smoothly, but in a series of impulses. Now connect that to a smoothly rotating propeller via a rotary tuning fork subject to 1100 HP worth of torque impulses at 3,000 RPM which passes right under the pilot's seat. Now imagine at full throttle this contraption takes a hit to the reduction gearbox, which either decouples the propeller, instantly way overreving and blowing the engine, or seizes the gearbox, snapping the shaft with the same result. Given that the engine is practically in the cockpit, and emergency egress is awkward at best, what does that say for survivability? Armor that gearbox, but "don't give me a P39!"


A hit in the reduction gearbox is the same whether it was mounted on the engine or remotely like the P-39. No other reduction gearboxes were armored.


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## P-39 Expert (Jan 6, 2021)

XBe02Drvr said:


> Yes, but with a significant supercharger advantage and a super lightweight and high lift airframe. Superior power giving superior thrust/weight, and superior L/D at altitude.


All the planes were tested and performance figures adjusted to standard day conditions. Planes in combat with each other all flew in the same atmosphere. The faster plane in standard day conditions will still be the faster plane in hot day conditions.


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## tyrodtom (Jan 6, 2021)

P-39 Expert said:


> A hit in the reduction gearbox is the same whether it was mounted on the engine or remotely like the P-39. No other reduction gearboxes were armored.


What other aircraft had a remote or separate gearbox like the P-39? P-63 ?


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## P-39 Expert (Jan 6, 2021)

tyrodtom said:


> What other aircraft had a remote or separate gearbox like the P-39? P-63 ?


None that i know of.


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## tyrodtom (Jan 6, 2021)

P-39 Expert said:


> All the planes were tested and performance figures adjusted to standard day conditions. Planes in combat with each other all flew in the same atmosphere. The faster plane in standard day conditions will still be the faster plane in hot day conditions.



You haven't thought that through. 
Some aircraft might have a cooling system that is up to keeping the engine cool enough to make full power on a standard day, but not good enough to cool it on a hot day.
The same can be true of the air induction system.


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## Milosh (Jan 6, 2021)

P-39 Expert said:


> None that i know of.


Piaggio P-119

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## jmcalli2 (Jan 6, 2021)

Stig1207 said:


> For an American made fighter it would have to be the P-51.
> 
> 
> 
> Overclaiming was hardly unique to either the Soviets or to the Eastern Front.




It's sort of a trick question.
It was the P-39 that shot down the greatest number of aircraft for an American built aircraft; the USSR shot down a LOT of German planes with it.

Much of that had to do with the nature of the Eastern Front air war. Lower altitudes, airfields closer to the front lines brought a lot of recon and transport aircraft into range; removing the wing guns to reduce weight and improve roll rate; removing the throttle stops made higher boost levels available at Eastern Front combat altitudes.
(The British noted that the P-39 was faster and more maneuverable than the Me-109 below 17,000 feet in their tests, and faster than the Spitfire (Mk V I think) below 15,000 feet by 18mph, equal at 17,000 feet; the Spitfire out turned the P-39 at all levels and was 55mph faster at 25,000 feet. The P-39 was exactly what the Russians needed.)
But most of the USSR's highest scoring aces scored most of their victories in the P-39, and their totals rivaled the German numbers: 3 over 60, 5 over 50, 18 over 40, and 30 over 30.
The P-39 was the last Luftwaffe kill of WWII, falling to a Me-262.
The P-39 scored the last Luftwaffe plane shot down in WWII, a FW-189.
US pilots score 320 kills in the P-39.

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## jmcalli2 (Jan 6, 2021)

Stig1207 said:


> In 1942 over New Guinea.



Funny not a mention of it here:





All the incoming Japanese bombers were picked up a few miles out.

At 200 mph a plane travels over 33 miles in ten minutes.
It took early models of P-39s that long to reach 20,000 feet.

That is why on almost every intercept in New Guinea they had to climb up first, then chase. It was rare for the P-39s up and waiting for the bombers as the AVG often was.

EDIT:

I went into the Kindle edition and searched for "warning." 

You were right, I was wrong. The P-39s did have SOME warning some of the time that "helped offset the P-39's rate of climb."

My apologies.


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## jmcalli2 (Jan 6, 2021)

XBe02Drvr said:


> What's your data source? I always heard the Hellcat and the Spitfire held the top spots.



Spitfire was not an American built aircraft.

Hellcat had the highest kill ratio of planes in US service during WWII.

The all time kill ratio, kills divided by combat losses, is held by the F-15; no other plane has ever shot one down, so it's ratio is infinity.


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## jmcalli2 (Jan 6, 2021)

tyrodtom said:


> That
> 
> 
> That's identified as the IFF in some cutaways.
> ...



https://airandspace.si.edu/webimages/collections/full/Pilot's flight manual for P-39 Airacobra.pdf
Manual for the P-39N-0 and N-1

http://www.wwiiaircraftperformance.org/P-39/P-39Q-1_Operating_Instructions.pdf
Manual for the P-39Q

The N manual identifies the one behind the pilot's head as the receiver, the one aft as the transmitter. That manual also includes instructions on the IFF and other radios, but I didn't find anything giving the location of them.

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## GrauGeist (Jan 6, 2021)

jmcalli2 said:


> Spitfire was not an American built aircraft.


But it's still Allied...


jmcalli2 said:


> Hellcat had the highest kill ratio of planes in US service during WWII.


Thought that distinction went to the Corsair.

And the tricky part, is to take into consideration the span of service and such.

Types like the SBD had an impressive kill to loss ratio and while I don't have the numbers handy, I beleive the Brewster Buffalo in Finnish service had one of the most impressive kill to loss ratios of any type.

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## Zipper730 (Jan 6, 2021)

*On the Short Stirling*


Simon Thomas said:


> Short Stirling + 112' wing span - 9000+ lbs of "good ideas" from the air ministry - 3° incidence by undercarriage extension = rather good bomber


I'm not really all that knowledgeable on the Shorts Stirling, but I'm not sure what you mean by the 9000 + pounds of "good ideas" from the Air Ministry.

As for the larger wingspan, I thought they reduced that because of the need to fit it in the hangars?


*On the XP-54*


wuzak said:


> I don't believe it was designed as a low altitude aircraft. It was supposed to have higher performance than aircraft then in production and the performance of fighters in development.


It seemed most of the desired area of performance sought was speed and climb. It would appear the turbochargers were added as the design evolved.


*On the He 177*

I'm curious if the Jumo would have been a better choice than the DB 601? From what I was reading about the German engine design, it seemed the best configured for higher coolant pressure which would make radiators smaller?


*On the P-61*

If I recall, they wanted eight hours loitering initially, then they superseded this requirement with either the demand eight hours loitering at low power, or two-hours at maximum-continuous, or "merely" two hours at maximum continuous power.

If the eight our requirement was simply replaced with the two-hour maximum continuous power requirement only, they really should have fitted a turbocharger to the design rather than going for the twin-stage supercharger arrangement: It would have given it better range and speed.

Does anybody have any power-curve charts for the P-61C?


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## Zipper730 (Jan 6, 2021)

davparlr said:


> To beat an old drum of mine, putting the big wing on the B-26 was the error. Instead, the AAF, and Navy should have started addressing adapting to faster flying, and landing, aircraft, which was the future.


What would that have entailed starting around 1940-1941?


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## GrauGeist (Jan 6, 2021)

Zipper730 said:


> *On the XP-54*
> It seemed most of the desired area of performance sought was speed and climb. It would appear the turbochargers were added as the design evolved.


The XP-54, XP-55 and XP-56 are responses the the Air Corp's 1939 request R-40C for an improved fighter (speed, firepower, etc.) And the XP-54, XP-55 and XP-56 were designed around the P&W X-1800 engine.

The XP-55 ended up with an Allison V-1710, the XP-54 ended up with a Lycoming XH-2460 and the XP-56 ended up with a P&W R-2800.


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## Milosh (Jan 6, 2021)

GrauGeist said:


> But it's still Allied...
> 
> Thought that distinction went to the Corsair.
> 
> ...


I believe that GregP has USN statistics. Maybe he can post then again.


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## jmcalli2 (Jan 6, 2021)

GrauGeist said:


> But it's still Allied...
> 
> Thought that distinction went to the Corsair.
> 
> ...



"Still Allied" was NOT THE QUESTION.


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## SaparotRob (Jan 6, 2021)

Did Soviet P-39’s ever encounter Finnish Buffaloes?

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## davparlr (Jan 6, 2021)

Zipper730 said:


> What would that have entailed starting around 1940-1941?


It should have been anticipated. Upgrades to the B-17 (B-29), and the A-20 (A-26), B-26, P-80. They should update primarily training. Handling increased take-off and landing speeds are not difficult if the operator understands and is familiar the required techniques. In 1940-41 time frame studies and tests should have been made so that training could be implemented quickly. As for the Navy, they should be studying how to improve efficiency and safety of carrier deck operations and how to handle heavier and faster aircraft. Instead they were busy making advance aircraft compatible with aircraft carriers designed to carry biplanes. Of course both services were up to their butt in alligators at the time.
.


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## wuzak (Jan 6, 2021)

Zipper730 said:


> *On the He 177*
> 
> I'm curious if the Jumo would have been a better choice than the DB 601? From what I was reading about the German engine design, it seemed the best configured for higher coolant pressure which would make radiators smaller?



Not sure if the Jumo 211 had been developed into a double engine, as the DB 601 was with the DB 606.

Unless you are talking of having the He 177 with 4 separate engines.


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## swampyankee (Jan 6, 2021)

tyrodtom said:


> What other aircraft had a remote or separate gearbox like the P-39? P-63 ?



No production airplanes that I've heard of, although quite a few prototypes. They are, however, very common in helicopters.


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## jmcalli2 (Jan 6, 2021)

SaparotRob said:


> Did Soviet P-39’s ever encounter Finnish Buffaloes?



I don't know, but I wondered the same thing!

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## Zipper730 (Jan 6, 2021)

davparlr said:


> It should have been anticipated.


You mean the trends that were occurring at the time with aircraft getting bigger and faster. The A-26 and P-80 weren't airborne in 1940-1941, the first flew in 1942, the other in early '44.


> In 1940-41 time frame studies and tests should have been made so that training could be implemented quickly.


Seems to make enough sense.


> As for the Navy, they should be studying how to improve efficiency and safety of carrier deck operations and how to handle heavier and faster aircraft. Instead they were busy making advance aircraft compatible with aircraft carriers designed to carry biplanes.


That sort of *is* adapting to higher performance aircraft.


> Of course both services were up to their butt in alligators at the time.


Alligators?



wuzak said:


> Not sure if the Jumo 211 had been developed into a double engine, as the DB 601 was with the DB 606.


Probably not, but it seemed that the requirements didn't seem to dictate two propellers at first. I was told that about 3% of a difference in top speed occurred with the same horsepower if four nacelles and props were used instead of two.


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## jmcalli2 (Jan 6, 2021)

GrauGeist said:


> The XP-54, XP-55 and XP-56 are responses the the Air Corp's 1939 request R-40C for an improved fighter (speed, firepower, etc.) And the XP-54, XP-55 and XP-56 were designed around the P&W X-1800 engine.
> 
> The XP-55 ended up with an Allison V-1710, the XP-54 ended up with a Lycoming XH-2460 and the XP-56 ended up with a P&W R-2800.



I always wondered if the XP-54 wouldn't have faired better with the V-3420 and ditching the "turret" in the nose. It certainly looked cool! 
I also wondered if all three (along with the XP-69 and XP-75) couldn't have been adapted to jet engines rather nicely...


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## Stig1207 (Jan 7, 2021)

XBe02Drvr said:


> What's your data source? I always heard the Hellcat and the Spitfire held the top spots.



Not that I can vouch for the validity of the numbers in the attachment, there are some differences in other sources, but it is close enough. The P-51 has almost 800 victories more than the Hellcat; I don't how many victories were achieved by Allied airforces with these two types, but I would think that the P-51 also leads the Hellcat.

The important thing to note is that the P-51 scored the majority of it's victories in the late war ETO, where claiming accuracy was better than it had been earlier and better than in other theatres. The Hellcat would be a contender for most shot down enemy aircraft by an American made fighter, if the claiming accuracy was just as good in the PTO, but I don't know if a case can be made for that.


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## Stig1207 (Jan 7, 2021)

jmcalli2 said:


> But most of the USSR's highest scoring aces scored most of their victories in the P-39, and their totals rivaled the German numbers: 3 over 60, 5 over 50, 18 over 40, and 30 over 30.



A high number of victories those necessarily mean an equally high number of enemy losses; been over it already in the groundhog thread #700.


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## Stig1207 (Jan 7, 2021)

jmcalli2 said:


> Funny not a mention of it here:
> View attachment 607818



I am pretty sure it is, seeing as it's the only book I've read on that particular campaign, but I can't tell you what page it's on as I've had to return it to the library.


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## XBe02Drvr (Jan 7, 2021)

P-39 Expert said:


> A hit in the reduction gearbox is the same whether it was mounted on the engine or remotely like the P-39. No other reduction gearboxes were armored.


Reread *and understand *post #727. The P39/63 were NOT like other aircraft.


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## XBe02Drvr (Jan 7, 2021)

P-39 Expert said:


> All the planes were tested and performance figures adjusted to standard day conditions. Planes in combat with each other all flew in the same atmosphere. The faster plane in standard day conditions will still be the faster plane in hot day conditions.


YOU JUST DON'T GET IT!

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## jmcalli2 (Jan 7, 2021)

Stig1207 said:


> Not that I can vouch for the validity of the numbers in the attachment, there are some differences in other sources, but it is close enough. The P-51 has almost 800 victories more than the Hellcat; I don't how many victories were achieved by Allied airforces with these two types, but I would think that the P-51 also leads the Hellcat.
> 
> The important thing to note is that the P-51 scored the majority of it's victories in the late war ETO, where claiming accuracy was better than it had been earlier and better than in other theatres. The Hellcat would be a contender for most shot down enemy aircraft by an American made fighter, if the claiming accuracy was just as good in the PTO, but I don't know if a case can be made for that.



The problem is at the top of the page:
"FLOWN BY US PILOTS"

That is a different statistic than "Shot down by US manufactured aircraft"


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## jmcalli2 (Jan 7, 2021)

Stig1207 said:


> A high number of victories those necessarily mean an equally high number of enemy losses; been over it already in the groundhog thread #700.



That assumes ALL P-39 victories were Me-109s.

A patently absurd idea.

I reject the article.

In THIS post.


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## jmcalli2 (Jan 7, 2021)

Stig1207 said:


> I am pretty sure it is, seeing as it's the only book I've read on that particular campaign, but I can't tell you what page it's on as I've had to return it to the library.



Could be, I have no interest in rereading the book again.

What I remember is that the P-39s had little warning of approaching raids, certainly not the amount of time the AVG had.


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## Milosh (Jan 7, 2021)

There is also something called 'target rich environment'. Europe and Eastern Front were 'tre' while the Pacific not so much.

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## davparlr (Jan 7, 2021)

Zipper730 said:


> You mean the trends that were occurring at the time with aircraft getting bigger and faster. The A-26 and P-80 weren't airborne in 1940-1941, the first flew in 1942, the other in early '44.


Much work was being done in the early 40s on upgrading war fighters. B-29 concepts started before the war, ditto with the A-26, and Lockheed was already studying design concepts for an advanced jet aircraft, the L-133. I should have also mentioned that they needed to define operational requirements for higher wing loaded aircraft, which, within four or five years would become prevalent. You shouldn't wait until the aircraft first flies to anticipate operational support.



> Alligators?


From an old saying
When you are up to your a** in alligators it’s difficult to remember that your job was to drain the swamp. Which means, that in this case, they were so busy fighting a war to address a lot of anticipated designs.

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## GrauGeist (Jan 7, 2021)

jmcalli2 said:


> That assumes ALL P-39 victories were Me-109s.
> 
> A patently absurd idea.
> 
> ...


*IF* one actually read the artical, then one would see that the artical stated (in Russian):


> Действительно, по данным Журнала боевых действий 5-й воздушной армии в воздушных боях лётчиками было сбито довольно внушительное количество вражеских самолетов – 240, из них: 122 Ме-109, 83 ФВ-190, 25 Ю-87, 4 Ю-88, 3 Хш-129, 1 Хш-123, 1 ФВ-189 и 1 ПЗЛ-24. Кроме того, на аэродромах было уничтожено 4 самолета


Which translates to (my bold for clarification):


> Indeed, according to the Journal of Combat Actions of the 5th Air Army in air battles, pilots shot down a rather impressive number of enemy aircraft - 240, of which: 122 *Me-109*, 83 *FW-190*, 25 *Ju-87*, 4 *JU-88*, 3 *HS-129*, 1 *HS-123*, 1 *FW-189* and 1 *PZL-24*. In addition, 4 aircraft were destroyed at the airfields.



So 118 EA downed out of 240 were NOT Bf109s...


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## jmcalli2 (Jan 7, 2021)

Stig1207 said:


> I am pretty sure it is, seeing as it's the only book I've read on that particular campaign, but I can't tell you what page it's on as I've had to return it to the library.




I went into the Kindle edition and searched for "warning." 

You were right, I was wrong. The P-39s did have SOME warning some of the time that "helped offset the P-39's rate of climb."

My apologies.

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## Stig1207 (Jan 8, 2021)

jmcalli2 said:


> The problem is at the top of the page:
> "FLOWN BY US PILOTS"
> 
> That is a different statistic than "Shot down by US manufactured aircraft"



I don't know how many victories British and Commonwealth had flying eg. P-51's, they would need to be added to statistic for American made aircraft.


jmcalli2 said:


> I went into the Kindle edition and searched for "warning."
> 
> You were right, I was wrong. The P-39s did have SOME warning some of the time that "helped offset the P-39's rate of climb."
> 
> My apologies.



No problem

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## jmcalli2 (Jan 8, 2021)

Stig1207 said:


> I don't know how many victories British and Commonwealth had flying eg. P-51's, they would need to be added to statistic for American made aircraft.



True. 
That would also apply to P-47s flying for Britain, Brazil, Free France, USSR, and Mexico.
It's all interesting.


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## P-39 Expert (Jan 8, 2021)

XBe02Drvr said:


> YOU JUST DON'T GET IT!


What am I not getting? Please enlighten me.


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## P-39 Expert (Jan 8, 2021)

jmcalli2 said:


> I went into the Kindle edition and searched for "warning."
> 
> You were right, I was wrong. The P-39s did have SOME warning some of the time that "helped offset the P-39's rate of climb."
> 
> My apologies.


From what I have read there were some coastwatchers in NG but not to the same extent as Guadalcanal. Guadalcanal had the advantage of being much farther away from Japanese bases so raids had to come in about the same time every day, around noon. In NG Port Moresby was less than 200mi from the Japanese bases at Lae so those raids could come at any time. No radar until August at Milne Bay and September at PM. There was Australian radar but it was just too far away to be effective.

Even after radar was installed at PM interceptions were often sent after clouds or flocks of birds. Still very primitive. But better than coastwatchers.

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## XBe02Drvr (Jan 8, 2021)

P-39 Expert said:


> What am I not getting? Please enlighten me.


In post #703, you stated:
"Extra boost would only be available up to the critical altitude of around 14000' with ram."
And I replied in post #711:
"And that density altitude would be at a much lower MSL physical altitude in a tropical climate."
To which you replied in post #714:
"Yes and your opponent would be flying in the same atmosphere."
And my reply was, in post #716:
"Yes, but with a significant supercharger advantage and a super lightweight and high lift airframe. Superior power giving superior thrust/weight, and superior L/D at altitude."
Which you either ignored or didn't comprehend. The Zero (ignore Koga's plane; it wasn't performing to capacity) has all the advantages enumerated above in any atmosphere, making the P39 of the time a *LOSER *any way you slice it. The only factors, as I see it, that allowed the New Guinea P39s to establish any sort of a win/loss record was the occasional tendency of teenage IJN pilots to exuberantly ignore their hard learned lessons of combat and play to the P39's strengths, as well as the ability of American pilots to un-learn their trained tactics and adapt to the new reality.


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## P-39 Expert (Jan 8, 2021)

XBe02Drvr said:


> In post #703, you stated:
> "Extra boost would only be available up to the critical altitude of around 14000' with ram."
> And I replied in post #711:
> "And that density altitude would be at a much lower MSL physical altitude in a tropical climate."
> ...


The supercharger and weight advantage you allude to would be operating in the same atmosphere as the P-39. If the P-39 was faster than the A6M2 in tests it would still be faster in theater since both planes would be at the same disadvantage. By the way, what supercharger advantage are you speaking of? Both planes had about the same critical altitude and speed bled off above that at about the same rate. See attached chart.


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## XBe02Drvr (Jan 8, 2021)

P-39 Expert said:


> A hit in the reduction gearbox is the same whether it was mounted on the engine or remotely like the P-39. No other reduction gearboxes were armored


YOU STILL DON'T GET IT!
On WWII era engines, the reduction gears weren't "mounted on" the engine, they were *integral *to it. A hit to the nosecase was a hit to the engine and would generally lead to failure, whether immediate or delayed. A "straight drive" engine, with no reduction gears like the P39 had, was an anomaly, not the norm. P39/P63 was different in that a hit to the reduction box could "unload" the engine, causing it to overspeed to destruction, with perhaps a catastrophic driveshaft failure, to boot. Not good for pilot survival.


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## P-39 Expert (Jan 8, 2021)

XBe02Drvr said:


> YOU STILL DON'T GET IT!
> On WWII era engines, the reduction gears weren't "mounted on" the engine, they were *integral *to it. A hit to the nosecase was a hit to the engine and would generally lead to failure, whether immediate or delayed. A "straight drive" engine, with no reduction gears like the P39 had, was an anomaly, not the norm. P39/P63 was different in that a hit to the reduction box could "unload" the engine, causing it to overspeed to destruction, with perhaps a catastrophic driveshaft failure, to boot. Not good for pilot survival.


I think I get it all right, in either case a hit to the nosecase, whether mounted on the engine or mounted remotely would result in failure of the engine. The nosecase mounted on the engine was not armored, why armor a remotely mounted nosecase? It was redundant and therefore not needed.


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## XBe02Drvr (Jan 8, 2021)

P-39 Expert said:


> The supercharger and weight advantage you allude to would be operating in the same atmosphere as the P-39. If the P-39 was faster than the A6M2 in tests it would still be faster in theater since both planes would be at the same disadvantage. By the way, what supercharger advantage are you speaking of? Both planes had about the same critical altitude and speed bled off above that at about the same rate. See attached chart.


I don't have a computer to hand at the moment, but on my tiny cellphone screen I can't make much sense of that chart. But this I did notice; the P39s in question were Ds, but the chart depicts Ks, which, IIRC, had more power and different supercharger gears. The A6M2 data, if derived from the Akutan Zero, is not accurate, as that plane was not perfectly restored and not performing to spec. (Issues with airframe rig, carburetor configuration, unknown "actual" engine limitations, reluctance to damage a valuable intelligence asset, etc). It's impossible to restore a damaged aircraft to spec without the proper documentation.

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## jmcalli2 (Jan 8, 2021)

XBe02Drvr said:


> In post #703, you stated:
> "Extra boost would only be available up to the critical altitude of around 14000' with ram."
> And I replied in post #711:
> "And that density altitude would be at a much lower MSL physical altitude in a tropical climate."
> ...



I agree except for the "loser any way you slice it."

Give the P-39 pilots the AVG early warning and tactics, and they would do at least as well by your own standards; the P-39 had the same engine and supercharger, a higher rate of climb, a lower wing loading, and a higher power/mass ratio than the P-40 of similar models. 

Even with the poor tactics, the P-39 was even in wins/losses with the Zero.
( reference Claringbould "P-39/P-400 vs. A6M2/3 Zero-sen New Guinea 1942 )

Or, should it be said this way: the vaunted Zero could do no better than fight the Airacobra to a draw over New Guinea.

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## XBe02Drvr (Jan 8, 2021)

P-39 Expert said:


> I think I get it all right, in either case a hit to the nosecase, whether mounted on the engine or mounted remotely would result in failure of the engine. The nosecase mounted on the engine was not armored, why armor a remotely mounted nosecase? It was redundant and therefore not needed.


Do you relish the thought of an engine exploding ten inches behind your precious posterior? Have you ever seen an engine that has come unglued due to an "unloaded" overrev at full throttle? Not pretty! Internal parts come right out through the engine crankcase. Scalding hot oil and coolant flying everywhere. Not healthy.
A hit to a front mounted engine's nose case is likely to continue on into the crankcase proper, as there's not much to stop it, bringing the engine to a halt without the "unloading" scenario described above.

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## P-39 Expert (Jan 8, 2021)

XBe02Drvr said:


> I don't have a computer to hand at the moment, but on my tiny cellphone screen I can't make much sense of that chart. But this I did notice; the P39s in question were Ds, but the chart depicts Ks, which, IIRC, had more power and different supercharger gears. The A6M2 data, if derived from the Akutan Zero, is not accurate, as that plane was not perfectly restored and not performing to spec. (Issues with airframe rig, carburetor configuration, unknown "actual" engine limitations, reluctance to damage a valuable intelligence asset, etc). It's impossible to restore a damaged aircraft to spec without the proper documentation.


K model engine was the -63 with the same 8.8 supercharger gears as the -35. It was strengthened and developed 1325hp at takeoff vs 1150 for the -35, but HP at critical altitude was the same 1150hp at 12000ft. So above 12000ft they made the same power. Performance of the D and K were virtually identical. I use the K chart because that's all I have.


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## P-39 Expert (Jan 8, 2021)

XBe02Drvr said:


> Do you relish the thought of an engine exploding ten inches behind your precious posterior? Have you ever seen an engine that has come unglued due to an "unloaded" overrev at full throttle? Not pretty! Internal parts come right out through the engine crankcase. Scalding hot oil and coolant flying everywhere. Not healthy.
> A hit to a front mounted engine's nose case is likely to continue on into the crankcase proper, as there's not much to stop it, bringing the engine to a halt without the "unloading" scenario described above.


And either way both engines stop working. Immediately.


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## P-39 Expert (Jan 8, 2021)

jmcalli2 said:


> I agree except for the "loser any way you slice it."
> 
> Give the P-39 pilots the AVG early warning and tactics, and they would do at least as well by your own standards; the P-39 had the same engine and supercharger, a higher rate of climb, a lower wing loading, and a higher power/mass ratio than the P-40 of similar models.
> 
> ...


You are correct, no P-40 was as fast or climbed nearly as well as any contemporary P-39. Being 750lbs lighter had its advantages.


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## XBe02Drvr (Jan 8, 2021)

P-39 Expert said:


> And either way both engines stop working. Immediately.


Front engine: pilot survival likely.
Rear (driveshaft) engine: not so much.


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## P-39 Expert (Jan 8, 2021)

XBe02Drvr said:


> Front engine: pilot survival likely.
> Rear (driveshaft) engine: not so much.


In your opinion. A round into the nosecase of a P-40 will cause the engine to slowly stop itself while a round into a P-39 nosecase will cause the engine to explode? Okay, if you say so.


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## XBe02Drvr (Jan 8, 2021)

P-39 Expert said:


> In your opinion. A round into the nosecase of a P-40 will cause the engine to slowly stop itself while a round into a P-39 nosecase will cause the engine to explode? Okay, if you say so.


In the P40's case the round will likely stop the engine, as it will continue on into its internals. In the P39, if it shatters the reduction gears or the driveshaft, it will likely "unload" the engine resulting in an over-rev catastrophic failure. An over-rev failure ten feet out in front of the cockpit (if it occurs) is more likely survivable than one ten inches behind.


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## Shortround6 (Jan 8, 2021)

P-40 doesn't have 10 feet of drive shaft running through the cockpit and nose. 

One reason the XP-39's claim to 390mph top speed is so suspect is that the engine in initial testing was limited to either 2600 or 2700rpm due to fears about the drive shaft having vibration problems should the engine misfire. A heavier drive shaft (larger diameter and heavier walls) was designed and fitted but not until the Plane had gone to Langley, 
Gearbox doesn't need to have a catastrophic failure, Not much you can do about the propeller but anything that throws the reduction gears out of wack balance wise will affect the vibration patterns.


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## GrauGeist (Jan 8, 2021)

A good comparison would be when a top-fuel funny car grenades it's rear-end.
The engine and driveline are no longer under load and catastrophic failure is the result.
Granted, the driveshaft loop and transmission shield help reduce the chance that the driver won't be injured or killed, but not always.

The P-39 did not have the benefit of modern drag racing safety protocols...

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## jmcalli2 (Jan 8, 2021)

GrauGeist said:


> A good comparison would be when a top-fuel funny car grenades it's rear-end.
> The engine and driveline are no longer under load and catastrophic failure is the result.
> Granted, the driveshaft loop and transmission shield help reduce the chance that the driver won't be injured or killed, but not always.
> 
> The P-39 did not have the benefit of modern drag racing safety protocols...



That's why no other aircraft has ever been designed with a drive shaft or counterrotating props since...

Except for:
many autogyros
XF5U
N-1M
FM-1
XF-84H
P-75
XB-42
B-35
B-36C
Do-335
J2M
A2D
Bristol 167
V-22
R-4
H-5
H-19/34
CH-47
plus many more helicopter designs, not to mention every turboprop design where the airscrew shaft is offset from the turbine shaft. All use driveshafts and remote gearboxes of varying lengths and configurations and with various degrees of success.

I've never heard of a P-39/63 drive shaft being a problem until these last few posts. That doesn't mean it wasn't a problem, but it does mean it's unlikely such problems were anything but a rare issue.

Could you be confusing armor with adequate structural strength?


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## XBe02Drvr (Jan 9, 2021)

jmcalli2 said:


> I've never heard of a P-39/63 drive shaft being a problem until these last few posts. That doesn't mean it wasn't a problem, but it does mean it's unlikely such problems were anything but a rare issue.


Quite likely it wasn't, *because *of the gearbox armor, and because in whatever cases may have occurred, there may have been no one left to tell about it.

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## GrauGeist (Jan 9, 2021)

A production P-39 off the assembly line is not likely to suffer a driveshaft/gearbox failure.
Once it's in combat, things change.
A bullet or cannon shell can alter the manufacturer's design specs in a fraction of a second.

And regarding the list, most of those types never left the prototype stage. The XF5U for example, which never flew because of dangerous vibrations at higher RPMs - the V-173 did, however.
The FM-1 had a radial engine mounted the same as the F4F/FM-2, not sure why it's on the list - same goes for the J2M. Perhaps you meant "YFM-1"?
And the B-36 didn't have a driveshaft.


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## jmcalli2 (Jan 9, 2021)

XBe02Drvr said:


> Quite likely it wasn't, *because *of the gearbox armor, and because in whatever cases may have occurred, there may have been no one left to tell about it.



If that were a problem, then why don't we see P-39s that belly landed torn up by driveshafts whipping around? The props stopping suddenly when hitting the ground would add as much if not more stress than a bulett hitting gears engineered to withstand huge amounts of stress.
Again, the structure wouldn't allow it, with or without the armor.


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## eagledad (Jan 9, 2021)

P-39 Expert

Attached is a graph for the P-39D-2, powered by the Allison V-1710 E-6 (Military designation V-1710-63).
For your use and information.

Eagledad

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## Glider (Jan 9, 2021)

Suggest you take a P39. Put the engine in front of the pilot, saving the weight and complexity of the drive shaft, its supporting structure and making it less twitchy on COG issues. Move the guns to the wings with uniform 0.50.
It would weigh a lot less than the P40 with similar power equalling a better performance.

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## Zipper730 (Jan 9, 2021)

eagledad said:


> P-39 Expert
> 
> Attached is a graph for the P-39D-2, powered by the Allison V-1710 E-6 (Military designation V-1710-63).
> For your use and information.
> ...


This is a good graph, and honestly it'd be a good idea to create more graphs of that detail.


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## XBe02Drvr (Jan 9, 2021)

jmcalli2 said:


> If that were a problem, then why don't we see P-39s that belly landed torn up by driveshafts whipping around?


Because in a belly landing the engine and prop would be turning at minimum power, if not at idle, the prop would be out of its governing range, and if the pilot had any sense at all, he would have killed the engine just before touch down and the prop would be wind milling down at time of impact. This would mean minimum stress on the entire drivetrain when the prop starts hitting the ground, especially since the high wing loading in a power off condition would result in a nose high touchdown so the prop blades get curled inward from the tips in a series of glancing blows instead of a single blade sudden stop.

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## eagledad (Jan 9, 2021)

Zipper730

I can't take credit for the graph, as I found it in the Wisconsin State Historical Library nearly 50 years ago! Been looking for performance graphs ever since. Found Nirvana with AHT. Mike Williams and Neil Sterlings web site and TAIC manuals.

Eagledad

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## Zipper730 (Jan 9, 2021)

eagledad said:


> I can't take credit for the graph, as I found it in the Wisconsin State Historical Library nearly 50 years ago! Been looking for performance graphs ever since. Found Nirvana with AHT. Mike Williams and Neil Sterlings web site and TAIC manuals.


It's hard to find graphs for certain aircraft, isn't it?

Regardless, I do like the way everything is laid out very well on one graph.


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## tyrodtom (Jan 9, 2021)

XBe02Drvr said:


> Because in a belly landing the engine and prop would be turning at minimum power, if not at idle, the prop would be out of its governing range, and if the pilot had any sense at all, he would have killed the engine just before touch down and the prop would be wind milling down at time of impact. This would mean minimum stress on the entire drivetrain when the prop starts hitting the ground, especially since the high wing loading in a power off condition would result in a nose high touchdown so the prop blades get curled inward from the tips in a series of glancing blows instead of a single blade sudden stop.



I am familiar with a case where a OH-6 tail rotor drive shaft come free from the tail rotor transmission, It whipped around,destroyed the tail boom, then got into the main rotor. It evidently happened so quick no mayday message got transmitted, Both occupants died.
It took a few weeks before the investigation determined the order of the failure from the scattered wreckage left.
And that was from a drive shaft that had only a fraction of that engine's power going through it.

Imagine in the P-39, the driveshaft going beneath the pilots butt, and then going forward right between his legs, and it's transmitting over 1000 hp.
Can you guess what would happen if the forward transmission failed and that driveshaft did detach from it. There would be no survivor, and scattered wreckage.
Under WW2 conditions, just how much investigation would there be ?
Maybe that's why that isolated forward gearbox was armored, some failure modes of it could be catastrophic .

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## Milosh (Jan 9, 2021)

Wasn't there a rumor that the vibration from the drive shaft in the P-39 would make the pilot impotent?


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## tyrodtom (Jan 9, 2021)

Milosh said:


> Wasn't there a rumor that the vibration from the drive shaft in the P-39 would make the pilot impotent?



There were tons of rumors in the military.
I remember one I heard in basic.
They put saltpeter in our food to make us impotent.


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## XBe02Drvr (Jan 9, 2021)

Milosh said:


> Wasn't there a rumor that the vibration from the drive shaft in the P-39 would make the pilot impotent?


The infamous "buzz balls" theory.


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## XBe02Drvr (Jan 9, 2021)

tyrodtom said:


> Maybe that's why that isolated forward gearbox was armored, some failure modes of it could be catastrophic .


The point I've been making all along. Now convince our favorite Ex-spurt.


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## SaparotRob (Jan 9, 2021)

XBe02Drvr said:


> The point I've been making all along. Now convince our favorite Ex-spurt.


Okay, you convinced me.


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## davparlr (Jan 9, 2021)

I'm having a hard time biting on the driveshaft issue. First, while I haven't read much about the P-39, and, while there are a lot of complaints about flying the plane, driveshaft issues and failures does not seem to pop up much. And this issue of getting a bullet through it causing catastrophic failures, how about a bullet or shell through a propeller blade, or hub, a fuel line, the pilot, or a control line. In wartime, an aircraft is not a safe place to be.


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## tyrodtom (Jan 9, 2021)

davparlr said:


> I'm having a hard time biting on the driveshaft issue. First, while I haven't read much about the P-39, and, while there are a lot of complaints about flying the plane, driveshaft issues and failures does not seem to pop up much. And this issue of getting a bullet through it causing catastrophic failures, how about a bullet or shell through a propeller blade, or hub, a fuel line, the pilot, or a control line. In wartime, an aircraft is not a safe place to be.


If you get a bullet through the propeller blade, it would depend on what size bullet, either a hole with a whistle and slight imbalance, keep flying.
Big shell through propeller, you'd might loose the blade outboard of the hole. Big imbalance that could shake the engine right out of it's mounts if you didn't shut the engine down in time.
Bullet in the hub, same thing , same as above..
Bullet in the fuel line ? Obvious result, reduced flight time, maybe fire.
Bullet in the pilot ? Maybe that's why they try to put a lot of armor around him. Of course something might get through with obvious results.
Bullet in the control line ? That's why they're made of cable, it takes a solid hit to sever the cable clear thru. If it does cut the control cable, or tube, or whatever, reduced control ability.

All those are not instant catastrophic failures, except maybe a bullet in the pilot's heart, or brain.

I've circle track raced for over 20 years, I've seen a loose drive shaft, from a broken back u-joint, flip a 3500 lb car instantly.
That's why most car racing associations require driveshaft hoops, front and rear, made from 1/4 in. steel.

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## Milosh (Jan 9, 2021)

tyrodtom said:


> I've circle track raced for over 20 years, I've seen a loose drive shaft, from a broken back u-joint, flip a 3500 lb car instantly.
> That's why most car racing associations require driveshaft hoops, front and rear, made from 1/4 in. steel.



Wouldn't that be a front U joint, which would act like a pole vault pole as the shaft dropped and dug in?


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## Simon Thomas (Jan 9, 2021)

Zipper730 said:


> *On the Short Stirling*
> I'm not really all that knowledgeable on the Shorts Stirling, but I'm not sure what you mean by the 9000 + pounds of "good ideas" from the Air Ministry.
> 
> As for the larger wingspan, I thought they reduced that because of the need to fit it in the hangars?


From "Short Stirling, The First of the RAF Heavy Bombers – Pino Lombardi"


> Shorts were constantly bombarded with 'minor' alterations to the original design. At one stage over 150 modifications had been requested; one was a requirement to carry small 50-lb bombs along the trailing edges of the wings.
> During early 1939, the all up weight of the Stirling had risen by some 9,000 lbs and was still creeping up doe to extra equipment required by the Air Ministry.



IIRC, one reference quoted 15,000 lbs of extra weight. To put this in context, it is roughly equivalent to the Stirling having to carry an empty de Havilland Mosquito or fully loaded Hawker Tempest. I am sure you could imagine the impact if the Stirling was ~15,000 lb lighter on every mission would have a significant impact on cruising altitude and speed. [Is there an easy way to determine the increase in cruise altitude with a weight reduction of 15,000 lbs?)


The 100 ft limit on the wing span was not related to hangars. I have read a few books on the Stirling, and there is no clear answer however most point to the Air Ministry using it to limit the all up weight. Which is rather ironic, considering the plethora of mandatory requirements which drove the weight so high in the finished product.

I have a WAG that watching the Stirling go from a reasonable aeroplane to an overweight underperformer may have taught the Air Ministry officials to not interfere as much. They did not allow Shorts to use the 112' wing they had already designed, and they were refused permission. Not that much later Avro and Handley Page wanted to add extra engines, and that was allowed. Adding extra engines would take considerably more time to engineer and get into production than using a wing design that already existed.

Mind you, this still happens today. The Royal Australia Navy wanted to buy helicopters, and then drowned them in specifications to the extent that they were incapable of entering service. Seasprite - The Billion Dollar Blunder

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## jmcalli2 (Jan 9, 2021)

eagledad said:


> P-39 Expert
> 
> Attached is a graph for the P-39D-2, powered by the Allison V-1710 E-6 (Military designation V-1710-63).
> For your use and information.
> ...



The V-1710-63 had a 1325hp rating on take off, the rest seems right.

http://www.enginehistory.org/References/ModDesig/jpg/I30.jpg

What I find fascinating about P-39 models is the seemingly haphazard manor of engine choices. 
Some models have engines with critical altitudes of 11 or 12,000 feet, and still others were 14 or 15,000 feet.





The choices seem to overlap P-39 models.

Data source: USAF Engine Models


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## jmcalli2 (Jan 9, 2021)

Milosh said:


> Wouldn't that be a front U joint, which would act like a pole vault pole as the shaft dropped and dug in?



The race car didn't have the heavy bearings bolted onto the frame the way the P-39 did. The race car's drive shaft has to take suspension movement into account. The P-39 didn't have universal joints.


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## jmcalli2 (Jan 9, 2021)

XBe02Drvr said:


> Because in a belly landing the engine and prop would be turning at minimum power, if not at idle, the prop would be out of its governing range, and if the pilot had any sense at all, he would have killed the engine just before touch down and the prop would be wind milling down at time of impact. This would mean minimum stress on the entire drivetrain when the prop starts hitting the ground, especially since the high wing loading in a power off condition would result in a nose high touchdown so the prop blades get curled inward from the tips in a series of glancing blows instead of a single blade sudden stop.



The stress of stopping would be more immediate on a belly landing.

A bullet would not sever the drive shaft!
Or, if it was big enough to, it would obliterate the aircraft and ANY armor it could carry.


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## GrauGeist (Jan 9, 2021)

The gearbox and reduction box at either end were armored for a reason.

The driveshaft transferred a great deal of energy and if either gearbox was damaged, then all that energy stored in the shaft under load has to go somewhere.

A bullet through the prop was not enough to stop the aircraft - a P-47 took a 20mm round through a prop and flew back to England. Matyer of fact, a P-47 flew through an Olive grove, bending back all four of the props (amongst other things) and still flew over 100 miles back to base.

So back to the core of the issue:
Is the armor at the prop's gearbox nessecary? Yes.
Is the armor at the engine's gearbox nessecary? Yes.
Reason for the armor? To prevent catastrophic failure if struck by projectiles while in combat.

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## tyrodtom (Jan 9, 2021)

Milosh said:


> Wouldn't that be a front U joint, which would act like a pole vault pole as the shaft dropped and dug in?



No in this particular case it was the rear u-joint, it hit the pavement hard enough to turn the car over, then the driveshaft slide out.
The front U-joint was still on the shaft, the rear broken U-joint half was still on the rear end.
Though I've seen it happen more often the way you describe.
After a few years of those types of mishaps, they started requiring drive shaft hoops on all RWD cars, no matter how little HP they have.
The rear U-joint breaking is by far the most destructive of the 2 failure modes.

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## tyrodtom (Jan 10, 2021)

jmcalli2 said:


> The race car didn't have the heavy bearings bolted onto the frame the way the P-39 did. The race car's drive shaft has to take suspension movement into account. The P-39 didn't have universal joints.



No u-joints maybe, but if the front gear box took damage that locked it up solid. 
That's where you get those fantastic pictures of the whole prop coming off.
What ever was weakest would fail, if it happened at the front of the drive shaft, coming out of the front gearbox, you'd have the drive shaft whipping around like a giant weed eater.

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## GrauGeist (Jan 10, 2021)

tyrodtom said:


> No in this particular case it was the rear u-joint, it hit the pavement hard enough to turn the car over, then the driveshaft slide out.
> The front U-joint was still on the shaft, the rear broken U-joint half was still on the rear end.
> Though I've seen it happen more often the way you describe.
> After a few years of those types of mishaps, they started requiring drive shaft hoops on all RWD cars, no matter how little HP they have.
> The rear U-joint breaking is by far the most destructive of the 2 failure modes.


Back in the 80's, I saw a Pro-street Charger blow his pumpkin on the launch and the driveshaft ripped free of the loops, launching it sideways through the fence and into the crowd.
No one was killed, but seeing that beast hurling into the crowd while we were dodging ring-gear, pinion and spline debris left a lasting impression.

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## Ascent (Jan 10, 2021)

As a job I work in an engine test house doing development work for various manufacturers. One time while doing an acceleration test on an engine the propshaft connection to the Dyno failed, this resulted in the propshaft destroying the solid metal guard mounted around it for just such an occasion. Fortunately most of it was contained but one end of the shaft spun around the test cell like a top and large metal bearings from the universal joint scattered around putting some big dents in a couple of pipes.

This was just a 2L, 4 cylinder engine, although it was around 6,000 rpm which an aero engine wouldn't achieve. Fortunately we have all sorts of control software to shut the engine down when they lose the load suddenly like that, but even so they massively over rev. That's not something you'd have in a WWII aircraft.

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## Koopernic (Jan 10, 2021)

PAT303 said:


> I would have liked to have seen the Spit reach it's full potential. The interim models were needed, MkV-IX-XIV but I can't help but think the blooding of the spit in 1941-42 by the likes of the FW190A would not have happened if the MkIII running 2 stage Merlin XX's could have been made.


The Merlin XX had a two speed supercharger drive but still single stage supercharger. The Merlin 60 with two stages, after-cooling and two speeds came much latter. 
Pretty much the ideal spitfire was the Mk VIII with the lower fueselage tank increased from 36 to 48 gallons and 2 x 12 gallon wing tanks and retractable tail wheel. If the tail tank used as a ferry tank in the simpler IX were added it would have impressive range though the tail tank would need to be half burned of before combat. Probably some machine tool company in Cincinnati saved the day with gear cutting machines to allow more gearboxes to be built.


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## jmcalli2 (Jan 10, 2021)

GrauGeist said:


> The gearbox and reduction box at either end were armored for a reason.
> 
> The driveshaft transferred a great deal of energy and if either gearbox was damaged, then all that energy stored in the shaft under load has to go somewhere.
> 
> ...



More like the AAF decided to armor everything on the P-39. Almost 250lbs worth for the smallest operational fighter since the P-26.

Once again, a bullet would not shake the drive shaft loose:

LiTOT: P-39: Why a Rear Engine Installation


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## jmcalli2 (Jan 10, 2021)

tyrodtom said:


> No u-joints maybe, but if the front gear box took damage that locked it up solid.
> That's where you get those fantastic pictures of the whole prop coming off.
> What ever was weakest would fail, if it happened at the front of the drive shaft, coming out of the front gearbox, you'd have the drive shaft whipping around like a giant weed eater.



It was designed and tested for that.

LiTOT: P-39: Why a Rear Engine Installation


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## GrauGeist (Jan 10, 2021)

jmcalli2 said:


> Once again, a bullet would not shake the drive shaft loose:


So you're saying that a bullet or cannon shell, which could tear apart aircraft engine blocks, was incapable of damaging either gearbox of a P-39?

Interesting...


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## jmcalli2 (Jan 10, 2021)

GrauGeist said:


> So you're saying that a bullet or cannon shell, which could tear apart aircraft engine blocks, was incapable of damaging either gearbox of a P-39?
> 
> Interesting...



Of course a bullet could disable the gearbox. That is not the discussion.
Remember the "reason" everyone gives for the armor in front of the gearbox; a bullet in the gearbox would cause the gearbox to explode and the driveshaft would then whip around and destroy the aircraft; that the same bullet hit on a P-40 gearbox would only kill the gearbox, not destroy the pilot via said whipping driveshaft; and what that armor could do: stop a .30cal bullet.
A "cannon shell" on a trajectory to hit the gearbox would not be stopped by the armor installed.
Therefore all the arguments were about a .30cal bullet causing the driveshaft to destroy the aircraft.
As can be seen here, the driveshaft/gearbox assembly was run for 20 hours in a way some believe would cause the driveshaft to whip around:

LiTOT: P-39: Why a Rear Engine Installation

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## GrauGeist (Jan 10, 2021)

I'm sure that pages upon pages of test results, graphs and illustrations are interesting, but as has been stated before: this is not under combat conditions.

If a standard fighter (radial or inline) suffers catastrophic failure of their gearbox, the result is the propeller coming free from the front of the engine - the point being that the P-39's gearbox was not impervious to damage, which is why it was protected by armor plate.

A .30 caliber bullet (7mm) can and will penetrate cast-iron, mild steel plate and so on. So will .50 caliber (13mm) and 20 and 30mm goes without saying.

A basic grasp of physics and a close look at the P-39 will make it clear that a failure of the shaft's gearbox (on either end) can wreak havoc on the interior of the fuselage in the event it comes free under load.

No one has implied the shaft will fail during testing, normal flight and so on, the conversation is about the need for armor and what can happen if the aircraft is in combat and suffers damage from enemy aircraft without the armor protection.

Evidently, Bell thought it was needed...


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## tyrodtom (Jan 10, 2021)

jmcalli2 said:


> Of course a bullet could disable the gearbox. That is not the discussion.
> Remember the "reason" everyone gives for the armor in front of the gearbox; a bullet in the gearbox would cause the gearbox to explode and the driveshaft would then whip around and destroy the aircraft; that the same bullet hit on a P-40 gearbox would only kill the gearbox, not destroy the pilot via said whipping driveshaft; and what that armor could do: stop a .30cal bullet.
> A "cannon shell" on a trajectory to hit the gearbox would not be stopped by the armor installed.
> Therefore all the arguments were about a .30cal bullet causing the driveshaft to destroy the aircraft.
> ...



I read that information BEFORE I entered this discussion, You seem to think it says something that it simply does not say.
They only tested it in a mock-up fixture that simulated a severe air frame distortion, but within it's design limits, but much longer that it was ever likely to occur.
They never tested it in a failure mode, such as the front driveshaft becoming detached from the gearbox.
They probably never tested it for that because they knew it was catastrophic .

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## jmcalli2 (Jan 10, 2021)

GrauGeist said:


> I'm sure that pages upon pages of test results, graphs and illustrations are interesting, but as has been stated before: this is not under combat conditions.
> 
> If a standard fighter (radial or inline) suffers catastrophic failure of their gearbox, the result is the propeller coming free from the front of the engine - the point being that the P-39's gearbox was not impervious to damage, which is why it was protected by armor plate.
> 
> ...




Well then we have the P-51s that disappeared due to entering a spacial anomaly from high diving speeds.

There is absolutely no evidence of this at all, but of course it happened on every mission a P-52 never came back from.

We know because those P-51s never came back.


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## jmcalli2 (Jan 10, 2021)

tyrodtom said:


> I read that information BEFORE I entered this discussion, You seem to think it says something that it simply does not say.
> They only tested it in a mock-up fixture that simulated a severe air frame distortion, but within it's design limits, but much longer that it was ever likely to occur.
> They never tested it in a failure mode, such as the front driveshaft becoming detached from the gearbox.
> They probably never tested it for that because they knew it was catastrophic .




Translation:
"You can cite page after page of studies, but I KNOW."

"To argue with a person who has renounced the use of reason is like administering medicine to the dead."
Thomas Paine


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## GrauGeist (Jan 10, 2021)

jmcalli2 said:


> Well then we have the P-51s that disappeared due to entering a spacial anomaly from high diving speeds.
> 
> There is absolutely no evidence of this at all, but of course it happened on every mission a P-52 never came back from.
> 
> We know because those P-51s never came back.


To be honest, that's an asinine analogy

Then it's up to YOU to prove the facts otherwise.
Start by sorting through USAAF, RAF and VVS loss reports and discount any catastrophic failures by enemy contact.

Take your time, we've got all day


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## swampyankee (Jan 10, 2021)

Did the P-39's driveshaft have any intermediate bearings?


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## jmcalli2 (Jan 10, 2021)

GrauGeist said:


> To be honest, that's an asinine analogy
> 
> Then it's up to YOU to prove the facts otherwise.
> Start by sorting through USAAF, RAF and VVS loss reports and discount any catastrophic failures by enemy contact.
> ...



It is an exact analogy of the argument of everyone claiming that a bullet in the gearbox would cause the drive shaft to whip around and destroy the aircraft.

I provided exactly as much prof for the P-51 time warp as they did for the P-39 drive shaft.

As for the P-39 drive shaft, I have posted several references backing up my position. those who disagree have provided zip, zero, nada to back up their claims.

So, some one, anyone show some documentation of an aircraft destroyed by a drive shaft gone wild after a bullet hits the remote gearbox.

No one has.


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## tyrodtom (Jan 10, 2021)

jmcalli2 said:


> Translation:
> "You can cite page after page of studies, but I KNOW."
> 
> "To argue with a person who has renounced the use of reason is like administering medicine to the dead."
> Thomas Paine



That's your translation of what I'm trying to get across.
I and several other people on this forum have seen what a powered loose drive shaft can do, and you refuse to accept that we saw what we saw.

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## GrauGeist (Jan 10, 2021)

jmcalli2 said:


> It is an exact analogy of the argument of everyone claiming that a bullet in the gearbox would cause the drive shaft to whip around and destroy the aircraft.
> 
> I provided exactly as much prof for the P-51 time warp as they did for the P-39 drive shaft.
> 
> ...


It appears you don't understand the difference between a P-39's power train versus other conventional types.
A typical radial powered fighter (Fw190, F6F, P-47, A6M, etc.) has the propeller assembly attached to the front of the engine, which is mounted foreward of the cockpit.
A typical inline powered fighter (Spitfire, P-40, Bf109, Yak-9, etc.) has the propeller assembly attached to the front of the engine, which is foreward of the cockpit.

The P-39 and P-63 as the engine mounted behind the cockpit, with a driveshaft extending 120 inches to the front of the aircraft, connecting to the propeller assembly via a gear reduction box (which is normally directly between the propeller and engine). It is this shaft, that carries a considerable amount of energy when under load.

As has been carefully explained by several people here, a shaft coming free under load can cause considerable damage and to think that the 120 inch long shaft in a P-39, under load, driven by over 1,000 horsepower cannot fail, nor ever did, during combat is a little odd.

That's like saying that a bullet could not possibly destroy a jet engine on the Me262...


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## ThomasP (Jan 10, 2021)

Hey Swampyankee,

re"Did the P-39's driveshaft have any intermediate bearings?"

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## XBe02Drvr (Jan 11, 2021)

ThomasP said:


> Hey Swampyankee,
> 
> re"Did the P-39's driveshaft have any intermediate bearings?"
> 
> View attachment 608535


Now we see "center bearing support for flexible splines coupling", and a whole new arena of potential disaster scenarios opens up. I hope that center bearing support is bolted to some mighty robust structure, or I see a potential wrecking ball.

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## XBe02Drvr (Jan 11, 2021)

GrauGeist said:


> to think that the 120 inch long shaft in a P-39, under load, driven by over 1,000 horsepower cannot fail, nor ever did, during combat is a little odd.
> 
> That's like saying that a bullet could not possibly destroy a jet engine on the Me262...


Almost certainly there would be no documented proof of its happening, if it occurred in a combat scenario.

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## XBe02Drvr (Jan 11, 2021)

GrauGeist said:


> Evidently, Bell thought it was needed..


...to keep the CG within limits, even if for no other reason.

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## XBe02Drvr (Jan 11, 2021)

jmcalli2 said:


> "To argue with a person who has renounced the use of reason is like administering medicine to the dead."
> Thomas Paine


EPITAPH FOR A NATION.

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## GrauGeist (Jan 11, 2021)

XBe02Drvr said:


> Now we see "center bearing support for flexible splines coupling", and a whole new arena of potential disaster scenarios opens up. I hope that center bearing support is bolted to some mighty robust structure, or I see a potential wrecking ball.


A follow-on to Thomas' diagram (in answer to Swampyankee's query), there was a center joint supported by a bearing.

Shown here, from a P-39Q, is the driveline between the V-1710-85 and the propellor's gearbox. The first segment of shaft (60 inches) runs beneath the cockpit. The last segment (60 inches) runs beneath the weapon bay.

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## XBe02Drvr (Jan 11, 2021)

GrauGeist said:


> Shown here, from a P-39Q, is the driveline between the V-1710-85 and the propellor's gearbox. The first segment of shaft (60 inches) runs beneath the cockpit. The last segment (60 inches) runs beneath the weapon bay.


Very interesting. And apparently devoid of U-joints.


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## special ed (Jan 11, 2021)

Now we need a description how the flexible splines coupling works.

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## P-39 Expert (Jan 11, 2021)

Glider said:


> Suggest you take a P39. Put the engine in front of the pilot, saving the weight and complexity of the drive shaft, its supporting structure and making it less twitchy on COG issues. Move the guns to the wings with uniform 0.50.
> It would weigh a lot less than the P40 with similar power equalling a better performance.


The drive shaft only weighed about 10lbs. If you put the engine in the front you increase the weight a couple hundred pounds for a new engine mount. Basically no engine mount on the P-39 since it was mounted on the wing.


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## P-39 Expert (Jan 11, 2021)

GrauGeist said:


> The gearbox and reduction box at either end were armored for a reason.
> 
> The driveshaft transferred a great deal of energy and if either gearbox was damaged, then all that energy stored in the shaft under load has to go somewhere.
> 
> ...


Reduction gearbox armor on the P-39 is unnecessary since no other planes had armored reduction gearboxes. Now the gearbox itself may be sturdy enough to withstand a direct hit, but I doubt it.

There were no structural issues with the driveshaft. No need for the nose gearbox armor plate, no issues with the symmetrical airfoil, and no tumbling problems. Only problem with the early P-39 was it was too heavy to climb above 20000ft with a drop tank. Dump the wing .30s and the nose armor and even that is fixed. Move on.


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## GrauGeist (Jan 11, 2021)

lmao...no other aircraft had nose armor because they didn't have 10 feet of driveshaft between it and the engine.

It's EXTREMELY obvious that a few people here don't understand why the gearbox was armored, but removing the armor would have been sheer folly and is why it was never done, so, move on.

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## GrauGeist (Jan 11, 2021)

Just an example of what a driveshaft can do when it fails under load:

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## XBe02Drvr (Jan 11, 2021)

GrauGeist said:


> Just an example of what a driveshaft can do when it fails under load:



Can you imagine that right underneath a full load of 37MM and .50 cal ammo?

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## XBe02Drvr (Jan 11, 2021)

P-39 Expert said:


> Reduction gearbox armor on the P-39 is unnecessary since no other planes had armored reduction gearboxes.
> There were no structural issues with the driveshaft. No need for the nose gearbox armor plate, no issues with the symmetrical airfoil, and no tumbling problems. Only problem was it was too heavy to climb above 20000ft with a drop tank. Dump the wing .30s and the nose armor and even that is fixed. Move on.



"To argue with a person who has renounced the use of reason is like administering medicine to the dead."
Thomas Paine

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## GrauGeist (Jan 11, 2021)

XBe02Drvr said:


> Can you imagine that right underneath a full load of 37MM and .50 cal ammo?


Notice that the shaft breached the safety devices and ripped through the Camero's steel floorpan and steel tunnel?

Typically, a stock driveshaft on a '69 Camaro weighs about 25 pounds, I'm guessing his was reinforced and rebalance for pro-street.

But a 10 foot long shaft, which had considerably more weight, coming loose in a predominately aluminum structure would be a terrible mess.

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## wuzak (Jan 11, 2021)

XBe02Drvr said:


> Can you imagine that right underneath a full load of 37MM and .50 cal ammo?



Or your balls!


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## wuzak (Jan 11, 2021)

P-39 Expert said:


> The drive shaft only weighed about 10lbs. If you put the engine in the front you increase the weight a couple hundred pounds for a new engine mount. Basically no engine mount on the P-39 since it was mounted on the wing.



The fuselage structure was stronger behind the pilot (the engine bay) than a typical aircraft with a nose mounted engine.

And the engine was not mounted on the wing.

Also, how much did the gearbox weigh?

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## BiffF15 (Jan 11, 2021)

wuzak said:


> Or your balls!



Testicular fortitude required.

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## XBe02Drvr (Jan 11, 2021)

BiffF15 said:


> Testicular fortitude required.


Armor plated codpiece, anyone?

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## GrauGeist (Jan 11, 2021)

wuzak said:


> Also, how much did the gearbox weigh?


Not sure about the gearbox's weight, but the shaft (each one) would have weighed at least 75 pounds. They weren't hollow like an automobile, but rather turned from solid stock (much like a hydraulic ram) in order to handle the torque between the engine and the prop's loading as well as being "tuned" (balanced rotationally).

I would also add that the center carrier bearing assembly that joined the two shafts weighed in the neighborhood of 10 pounds.

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## wuzak (Jan 11, 2021)

GrauGeist said:


> Not sure about the gearbox's weight, but the shaft (each one) would have weighed at least 75 pounds. They weren't hollow like an automobile, but rather turned from solid stock (much like a hydraulic ram) in order to handle the torque between the engine and the prop's loading as well as being "tuned" (balanced rotationally).



75lbs each? I was assured that it only weighed 10lb!

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## wuzak (Jan 11, 2021)

special ed said:


> Now we need a description how the flexible splines coupling works.



I would think that the male spline would be spherical and the female spline straight.

This would allow for small misalignments in the shafts and the forward shaft to translate fore/aft as the airframe flexes.

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## GrauGeist (Jan 11, 2021)

wuzak said:


> 75lbs each? I was assured that it only weighed 10lb!


I saw that original comment and figured it was supposed to read "100 pounds", which would be realistic.


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## Shortround6 (Jan 11, 2021)

There may have been 3 different shafts used between the XP-39 and production P-39s.

The XP-39 was fitted with shafts of 2.500 diameter and 0.156 wall thickness to begin with but new shafts were fabricated while the XP-39 was at Langley. 
The New shafts (weight increase 11-15lbs but not specified as to each shaft or both shafts) were 2.550 in diameter and wall thickness 0.200.

Production P-39s got 3.000 diameter shafts that were only 5 lbs heavier (book doesn't give wall thickness.) all in the larger couplings and flanges. 
The 3 in shafts were supposed to have the same torsional characteristics as the 2.550 in shafts. 


a 60 in solid shaft 3 in in diameter would weigh about 118lbs (?) depending on exact alloy.

BTW the Shaft is one of the reasons there is considerable doubt about the XP-39 ever coming close to 390mph in it's original form (pre Langley) as the engine was restricted to either 2600rpm or 2700rpm due to potential vibration problems should the engine misfire at higher RPM. 

The 2nd shaft was supposed to be about 30% stiffer and raised the vibration problem area by 400rpm which was above the normal operating range of the Allison at that time. 

The entire drive shaft may have weighed 100lbs? (or 50lbs plus the fuselage weighing another 50lbs more than a front engine plane due to extra stiffening?)
I can't remember were I read that or the exact numbers assigned to each part (shaft/s and fuselage) 

The drive shaft (the the flexible coupling in the middle) was designed to accommodate +/- 1 degree of misalignment between the engine drive flange and the gearbox input flange.
This was supposed to be a total of 3.64in of possible travel over 10 ft.

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## Admiral Beez (Jan 11, 2021)

tomo pauk said:


> OTOH - engine was firmly behind the curve by 1940.
> All in all, perhaps going with Fulmar or Henley as a dive bomber nets you a better solution for 1939-42?


That's probably where the Skua needs help the most, where its 905 hp Perseus (55" dia, 1,025 lb) engine needs a replacement. What pre-Hercules options do we have? The Bristol Taurus is rated at 1,050 hp and at 46" wide and 1,301 lb. it could allow the Skua's engine bay to be narrowed and more streamlined, but it's 30% heavier. 

If we're keeping the Perseus, reject the fighter role and remove two of the forward .303 guns to allow for a heavier bombload.


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## jmcalli2 (Jan 11, 2021)

tyrodtom said:


> That's your translation of what I'm trying to get across.
> I and several other people on this forum have seen what a powered loose drive shaft can do, and you refuse to accept that we saw what we saw.



You saw a drive shaft on a CAR.

My point is that the P-39 drive shaft is secured in a way the car's drive shaft is not.

AND that a .30cal bullet would NOT sever that driveshaft.

Your argument is back to, "I KNOW."

Show me where it happened to a P-39.

I'll wait.


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## Shortround6 (Jan 11, 2021)

Yanking a pair of 24lb guns and about 80lbs of ammo (600rpg ? 1200 rounds total) isn't going to do much for the bomb load.

The 905 HP Perseus made the 905hp at 6,500ft. 
The Production Taurus engines were mostly rated at 3500ft. using 100/130 fuel. (1130hp?) 
Of course it took a while to solve the Taurus engine overheating problem/s. 

You could get a single speed Pegasus to have 1,010hp for take-off and 890hp at 6,500ft using 87 octane fuel and be about 165lbs lighter than the Taurus. 
A two speed Pegasus offers a lot of improvement without the sleeve valve troubles.


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## jmcalli2 (Jan 11, 2021)

GrauGeist said:


> It appears you don't understand the difference between a P-39's power train versus other conventional types.
> A typical radial powered fighter (Fw190, F6F, P-47, A6M, etc.) has the propeller assembly attached to the front of the engine, which is mounted foreward of the cockpit.
> A typical inline powered fighter (Spitfire, P-40, Bf109, Yak-9, etc.) has the propeller assembly attached to the front of the engine, which is foreward of the cockpit.
> 
> ...




It appears you haven't bothered to read my other posts.
Start with Improve That Design: How Aircraft Could Have Been Made Better

Notice that the drive shaft is supported in the front, rear, and center by the P-39's main structure,

Then read Improve That Design: How Aircraft Could Have Been Made Better

Notice that the P-39 driveshaft installation was tested extensively.

A .30cal bullet hitting the gearbox would NOT cause the P-39 driveshaft to whip around.

Show me some documentation that it ever happened.

I'll wait.


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## GrauGeist (Jan 11, 2021)

Shortround6 said:


> There may have been 3 different shafts used between the XP-39 and production P-39s.
> 
> The XP-39 was fitted with shafts of 2.500 diameter and 0.156 wall thickness to begin with but new shafts were fabricated while the XP-39 was at Langley.
> The New shafts (weight increase 11-15lbs but not specified as to each shaft or both shafts) were 2.550 in diameter and wall thickness 0.200.
> ...


I recall reading (ages ago) that they tested quite a few different types (hollow, solid, fluid filled, etc.) and different alloys to address a host of potential issues.
The division General Motors created just for this project did come up with a winner, though.
The P-39 may not have been all it was expected to be, fighter-wise, but it was certainly one hell of an engineering job.

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## tyrodtom (Jan 12, 2021)

jmcalli2 said:


> It appears you haven't bothered to read my other posts.
> Start with Improve That Design: How Aircraft Could Have Been Made Better
> 
> Notice that the drive shaft is supported in the front, rear, and center by the P-39's main structure,
> ...



To be .30 caliber proof is just how useful when all Bf-109s from the late F up had two 20mm wing cannon in addition to the usually .50 cal. cowl guns.
The armament situation for the Bf109 is so confusing, late B's had 4 .30s, middle E models had 2 .30s, and 2 20mm, the F model had so many configurations, 15mm, .50 caliber, 20mm, and ???
But once the G model came out I don't think there were any more .30 armed Bf109s.
The F model was just coming into service when Germany invaded the USSR.
Then the Fw190 had wing cannons from the beginning, in addition to the cowl .30s.

So just how useful is .30 caliber proof, when almost any opponent you're going up against has heavier armament ? 
I think you're being deliberately obtuse about the realities of most of the actions the P-39 was involved in, especially the war on the eastern front. .
Planes lost in action , for any cause, very seldom could have any investigation, the most intense conflict the world has ever seen was going on.

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## tomo pauk (Jan 12, 2021)

Admiral Beez said:


> That's probably where the Skua needs help the most, where its 905 hp Perseus (55" dia, 1,025 lb) engine needs a replacement. What pre-Hercules options do we have? The Bristol Taurus is rated at 1,050 hp and at 46" wide and 1,301 lb. it could allow the Skua's engine bay to be narrowed and more streamlined, but it's 30% heavier.
> 
> If we're keeping the Perseus, reject the fighter role and remove two of the forward .303 guns to allow for a heavier bombload.



As noted by SR6, a 2-speed suprcharged Pegasus is probably the best choice for the Skua - engine is light enough, reliable, no-nonsense and in production, can do another ~100 HP for take off, while also offering much more power at altitude.


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## Milosh (Jan 12, 2021)

tyrodtom said:


> But once the *G model* came out I don't think there were any more .30 armed Bf109s.


That should be G-6.

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## XBe02Drvr (Jan 12, 2021)

GrauGeist said:


> the shaft (each one) would have weighed at least 75 pounds. They weren't hollow like an automobile, but rather turned from solid stock (much like a hydraulic ram) in order to handle the torque between the engine and the prop's loading





Shortround6 said:


> The XP-39 was fitted with shafts of 2.500 diameter and 0.156 wall thickness to begin with





Shortround6 said:


> The New shafts (weight increase 11-15lbs but not specified as to each shaft or both shafts) were 2.550 in diameter and wall thickness 0.200.





Shortround6 said:


> Production P-39s got 3.000 diameter shafts that were only 5 lbs heavier


We seem to have a contradiction here. First, it's a solid shaft, then it appears to be a hollow shaft with various specified wall thicknesses. Which is it? A solid shaft seems rather unlikely from a weight standpoint, but then a 1/5" thick wall hollow one seems rather delicate for the forces involved. I'm no engineer, but that doesn't feel right "in the gut".


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## Koopernic (Jan 12, 2021)

Milosh said:


> That should be G-6.


The Me 109G1 was as clean a machine as the Me 109F4. However by the time time of the Me 109G5/G6 had
1 Developed bulges over the engine where the large 13.2mm MG131 replaced the rifle calibre MG81
2 Bulges over the wings to incorporate enlarged wheels
3 Lost its retractable tail wheel
4 Didn't have wheel covers.
These problems were probably mostly fixed by the Me 109K1 but it was delayed at least 7 months due to bombing and loss of plans we didn't see them fixed till the Me 109K4 in October 1944.

The major issue of the Me 109G was the lack of range. A small tank (about 100L) was added to the rear but although it was meant to be plumbed for Nitrous Oxide, Methanol-Water or Extra Fuel seems to have carried MW50 most of the time.

A secondary issue was the lack of fire power for engaging 4 engine bombers. This was partially remedied by removable underslung gondola weapons. Latter in the Me 109K6 30mm MK108 canon were to be integrated within the wing.

Why not fit MG131 13.2mm within the wing in 1942? The rifle calibre guns can remain in the cowling without bulges.

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## Admiral Beez (Jan 12, 2021)

tomo pauk said:


> As noted by SR6, a 2-speed suprcharged Pegasus is probably the best choice for the Skua - engine is light enough, reliable, no-nonsense and in production, can do another ~100 HP for take off, while also offering much more power at altitude.


Sounds like a good plan.

Can we get heavier bomb load? It's more than engine power, but also the weight of the bomb cradle and mounts. We also need a reasonable takeoff speed for carrier ops. Also, can the undercarriage and hook hold up if we're carrying a full load and for example a 1,000 lb. GP or AP bomb (we'll need to design the latter) and need to return to the carrier? We don't want to be dumping ordinance into the sea after every patrol.


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## special ed (Jan 12, 2021)

Not wanting to derail the thread, I would still like to know how the flexible splines coupling worked. If as suggested a spherical end within tubed splines, then lubrication, especially in a combat aircraft, would be critical. The spherical splined part would not have full contact with fixed splines. Perhaps an expert on the P-39 may have the answer.


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## GrauGeist (Jan 12, 2021)

The shaft at either end (engine/gearbox) would pass through a seal in the housing, much like the front and rear seal on your car's engine where the ends of the crankshaft emerge for the crank pulley and the transmission drive.
The P-39's gearbox (in the nose) had a 2 gallon oil tank that provided lubrication and the shaft's coupling would have been lubricated along with the reduction gears and prop coupling.
The rear of the shaft entering the engine's output coupling would have been lubricated by the engine's oiling system.
The shaft's center carrier bearing assembly would have been greased like your car's driveshaft U-joints or other joints, either by packing or via "zirc fittings" (I'm not sure which).

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## GregP (Jan 12, 2021)

The P-38 was the ARMY fighter that shot down the most enemy aircaft in the Pacific Theaters, not the single aircraft, regardless of service, that shot down the most enemy aircraft for the entire war.


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## swampyankee (Jan 12, 2021)

Torsional stress on a shaft is torque time radius divided by second moment of the area. For a thin-walled tube, this reduces to torque divided by (twice the thickness times the tube area). See Torsion Equations - Roy Mech


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## P-39 Expert (Jan 12, 2021)

jmcalli2 said:


> The V-1710-63 had a 1325hp rating on take off, the rest seems right.
> 
> http://www.enginehistory.org/References/ModDesig/jpg/I30.jpg
> 
> ...


A few corrections need to be made (as usual).

The first D is actually a D-2.

The second L is incorrect, I don't believe a production L had a -83 engine, just the -63.

The M had the -83, [email protected]'.

The N had the -85, same rating as the -83, just a different reduction gear from 2.0 to 2.23.

All Qs had the -85 like the N with 1200HP for takeoff and [email protected]'. Or [email protected]', take your pick.

The 11800' models are often listed at 12000' and have the earlier 8.8 supercharger gears. The 14600' models have the later 9.6 supercharger gears but these engines still had the port backfire screens which would be deleted from all V-1710 models with the introduction of the aluminum intake manifolds in mid-'42. The production 9.6 models (-83 and -85) never had the backfire screens since they were gone before the 9.6 models started production in August '42. Backfire screens were a real nuisance since they clogged quickly and getting rid of them improved critical altitude by 900' (14600' to 15500').

The -59 in the P-39J was an early attempt (Dec '41) at the 9.6 gears but they couldn't pass the 150 hour test and were converted back to 8.8 geared models. Only 25 -J models produced so basically disregard this model. The accessories drive was redesigned for wider 9.6 gears that would pass the 150 hour test but that set the program back about 8 months in 1942 (Dec-Aug). The M was the first user with production of that plane beginning in October 1942.

Simple, eh? It was pretty much chronological with the -35 in the P-400, D, D-1, and F, the -63 in the D-2, K and L, the -83 in the M and the -85 in the N and Q. The -35 and -63 had the 8.8 gears and the -83 and -85 had the 9.6 gears.

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## XBe02Drvr (Jan 12, 2021)

jmcalli2 said:


> A bullet would not sever the drive shaft!


QUOTE="jmcalli2, post: 1609575, member: 45349"]Once again, a bullet would not shake the drive shaft loose[/QUOTE]
It wouldn't need to. What's going to happen when a hollow tube carrying the torque from 1150 HP in walls .020" thick at 3,000 RPM, carefully balanced and tuned to avoid resonances, is holed or furrowed by a 7.7MM round, upsetting all that balancing and tuning? I suspect the shaft would shake itself loose, possibly ripping the intermediate coupling loose from its supporting structure.


jmcalli2 said:


> Of course a bullet could disable the gearbox. That is not the discussion.


Actually, it is. Imagine you're in a dogfight, pulling 3,000 RPM and all the MP the supercharger will give you, plus fluctuating G and gyroscopic loads from your gyrations, and your reduction gearbox is disabled, suddenly unloading that engine right behind your seat. Wide open throttle and no load on the crankshaft, what do you think is going to happen? Right, it's going to come unglued. Spectacularly. The only question is how many revs it'll hit before it does. 3,500? 4,000? Who cares? You won't. The scalding glycol and engine oil will have seen to that. And nobody will be around to tell the tale.
Reduction gearbox armor was essential.

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## P-39 Expert (Jan 12, 2021)

XBe02Drvr said:


> QUOTE="jmcalli2, post: 1609575, member: 45349"]Once again, a bullet would not shake the drive shaft loose


It wouldn't need to. What's going to happen when a hollow tube carrying the torque from 1150 HP in walls .020" thick at 3,000 RPM, carefully balanced and tuned to avoid resonances, is holed or furrowed by a 7.7MM round, upsetting all that balancing and tuning? I suspect the shaft would shake itself loose, possibly ripping the intermediate coupling loose from its supporting structure.

Actually, it is. Imagine you're in a dogfight, pulling 3,000 RPM and all the MP the supercharger will give you, plus fluctuating G and gyroscopic loads from your gyrations, and your reduction gearbox is disabled, suddenly unloading that engine right behind your seat. Wide open throttle and no load on the crankshaft, what do you think is going to happen? Right, it's going to come unglued. Spectacularly. The only question is how many revs it'll hit before it does. 3,500? 4,000? Who cares? You won't. The scalding glycol and engine oil will have seen to that. And nobody will be around to tell the tale.
Reduction gearbox armor was essential.[/QUOTE]

_________________________________________________________________________________________________________________________________________

All the reading I have done on the P-39 I've never read of a driveshaft problem, never read that the shaft was struck by a bullet, never read that the shaft came loose, no Bell tech reps ever heard of the reduction gears being struck. The nose armor would be unlikely to stop anything larger than a .30cal round anyway, and maybe not even that. Nose armor was useless redundant weight mostly for ballast pending expected larger, heavier propellers. No other planes had nose reduction gear armor.


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## swampyankee (Jan 12, 2021)

While I am far from a big fan of the P-39 -- I feel there were far more disadvantages to the mid-engine location than advantages -- in fighter-vs-fighter combat the vast majority of hits will be from the rear aspect, where the drive shaft and reduction gearing is well-protected by the bulk of the airframe. From the front aspect, a P-39 would likely be targeted by flexibly-mounted guns. The gearbox will be a small target and will also shield the drive shaft.

Alas, I've no access to detailed causes of P-39 and P-36 combat losses.

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## XBe02Drvr (Jan 13, 2021)

P-39 Expert said:


> All the reading I have done on the P-39 I've never read of a driveshaft problem, never read that the shaft was struck by a bullet, never read that the shaft came loose.


You wouldn't. Dead men tell no tales. Combat losses are generally not accessible for investigation.

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## GrauGeist (Jan 13, 2021)

It's not the shaft being hit by a bullet that's cause for concern, it's the gearbox being damaged.

Plenty of people have pointed out that if the gearbox is damaged, the shaft will bind and let go (just like the Camaro video posted), which is WHY it was protected by armor.

Not sure how many times this point needs to be repeated, but, here we are once again...

And this:
"No other planes had nose reduction gear armor."
Seriously?? How many other fighters had 10 feet of driveshaft between their engine and prop? 
As has been said over and over and over and over: conventional fighters (radial and inline) did not need armor on their gearbox because if it took damage, the very worst that would happen is the engine would bind and worse-case scenario, the prop would come apart - at which point, the pilot would most likely want to bale out.

The P-39/P-63 was the only production fighter with 10 feet of spinning steel underneath the pilot, who would be beat to death by the shaft in the event the gearbox was damaged.

I thought this was a fairly straight-forward point being made - but it appears I was wrong...

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## GrauGeist (Jan 13, 2021)

And to touch on the P-39 armor "thing" - I appreciate the exhaustive attempts to try to reimagine the P-39 into a world beater by moving this and eliminating that, so it would maybe, somehow, be better than it was.

So let's do this:
We'll remove the gearbox armor and while we're at it, let's remove the 2 gallon oil tank, too. Then let's get rid of the Olds 37mm cannon, way too heavy.
It seems to me that the driveshaft assembly is extra weight we don't need, so that goes.
What's next - oh yeah, CoG issues, so let's move the engine to the front where all that empty space is and maybe adjust the mainwing a bit to balance things out. Nice.
Now the two cowl .50MGs will have to go in the wings with the others, of course.
Ahh yeah, let's get rid of the nosegear, way too heavy - a tailwheel will do just fine, less weight, you know.

So now we get to see the what we've created and...what do we have? A P-40 - that's what we have.

Someone better get the DeLorean and go back and tell Bell!

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## P-39 Expert (Jan 13, 2021)

Find one instance where the driveshaft gave way. One. 9500 examples produced, in combat all over the world in all kinds of weather. 

Find one instance where a P-39 took a round in the nose armor. One. In all of history.

Dead men tell no tales? Well you're telling a big one right now.


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## pbehn (Jan 13, 2021)

P-39 Expert said:


> Find one instance where a P-39 took a round in the nose armor. One. In all of history.


With all those produced and used in combat, an absence of any plane that took a hit in the nose armour and returned is evidence that it was fatal not that it didn't happen, that is survivorship bias The Statistics That Kept Countless Allied Fighter Planes In The Sky . I don't know about the P-39 history, just stating the general principle.

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## pbehn (Jan 13, 2021)

GrauGeist said:


> So now we get to see the what we've created and...what do we have? A P-40 - that's what we have.
> 
> !


Or a P-51 or that very rare Allison engined Spitfire.


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## XBe02Drvr (Jan 13, 2021)

pbehn said:


> Or a P-51 or that very rare Allison engined Spitfire.


Or a P51? Larry Bell may have had some experience at Consolidated, but he was no Dutch kindelberger. Not by a long shot.


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## pbehn (Jan 13, 2021)

XBe02Drvr said:


> Or a P51? Larry Bell may have had some experience at Consolidated, but he was no Dutch kindelberger. Not by a long shot.


Just a joke on the general principle.

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## swampyankee (Jan 13, 2021)

pbehn said:


> With all those produced and used in combat, an absence of any plane that took a hit in the nose armour and returned is evidence that it was fatal not that it didn't happen, that is survivorship bias The Statistics That Kept Countless Allied Fighter Planes In The Sky . I don't know about the P-39 history, just stating the general principle.



Since there’s no evidence, there’s no evidence that it happened, either. One way to see how likely gearbox damage is to examine the damage records of twins, especially twin fighters.


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## XBe02Drvr (Jan 13, 2021)

GrauGeist said:


> So now we get to see the what we've created and...what do we have? A P-40 - that's what we have.


No, we have a smaller, lighter, P40 wannabe that probably can outperform the P40 in the interceptor role, but is nowhere near as versatile, and can't hold a candle to it in attack and CAS modes. That small wing with its symmetrical airfoil impairs its ordnance lift capacity and increases its runway length requirements.


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## GrauGeist (Jan 13, 2021)

XBe02Drvr said:


> No, we have a smaller, lighter, P40 wannabe that probably can outperform the P40 in the interceptor role, but is nowhere near as versatile, and can't hold a candle to it in attack and CAS modes. That small wing with its symmetrical airfoil impairs its ordnance lift capacity and increases its runway length requirements.


Of course, I was being facetious, but in reality, there was only a few feet difference (length/width) between the two.

Now Bell's XP-77 was most certainly smaller - but definately no better than the P-39's spin-offs: XFL, XP-76.


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## jmcalli2 (Jan 13, 2021)

tyrodtom said:


> To be .30 caliber proof is just how useful when all Bf-109s from the late F up had two 20mm wing cannon in addition to the usually .50 cal. cowl guns.
> The armament situation for the Bf109 is so confusing, late B's had 4 .30s, middle E models had 2 .30s, and 2 20mm, the F model had so many configurations, 15mm, .50 caliber, 20mm, and ???
> But once the G model came out I don't think there were any more .30 armed Bf109s.
> The F model was just coming into service when Germany invaded the USSR.
> ...



Again YOU HAVE NO IDEA WHAT THE CONVERSATION IS ABOUT!

It is about the armor in front of the gearbox.

ARMOR THAT WOULD NOT STOP A 20mm SHELL.


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## jmcalli2 (Jan 13, 2021)

XBe02Drvr said:


> No, we have a smaller, lighter, P40 wannabe that probably can outperform the P40 in the interceptor role, but is nowhere near as versatile, and can't hold a candle to it in attack and CAS modes. That small wing with its symmetrical airfoil impairs its ordnance lift capacity and increases its runway length requirements.



The P-40 had two advantages over the P-39:
1. longer range on internal fuel;
2. early production. 7,478 P-40s and 2,912 P-39s were delivered by the end of '42.

As for being "more versatile," P-40 production began in May 1940 and stopped in November 1944 with 13,738 built. 
Nothing replaced it on Curtiss assembly lines.

P-39 production began in December 1940 and ended in August '44 with 9,588 built; P-63 production began in January '44 (31 P-63s were delivered in '43) and continued through June '45 with 3,303 built (including 30 delivered between September 1945 and April 1946) for a total of 12,891 'Cobras built.

Both lines slowed down from peaks of 463 P-40s in August '43 and 503 P-39s July '43 to 200 P-40s in May '44, with 201 P-39s and 110 P-63s the same month.

The US didn't need the P-39/63 by early '44; they were built for the USSR.

The USSR wanted P-39s and P-63s.

The US didn't need any P-40s by early '44 and the USSR didn't want anymore P-40s; so P-40 production ended.

Being "more versatile," whatever that means, didn't keep the P-40 in demand as long as the P-39/63 line.


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## jmcalli2 (Jan 13, 2021)

P-39 Expert said:


> A few corrections need to be made (as usual).
> 
> The first D is actually a D-2.
> 
> ...




I got my engine model info from USAF Engine Models 

The chart does not say how many of a specific model carried the specified engine; could be one, could be more of the production run.


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## jmcalli2 (Jan 13, 2021)

XBe02Drvr said:


> QUOTE="jmcalli2, post: 1609575, member: 45349"]Once again, a bullet would not shake the drive shaft loose


It wouldn't need to. What's going to happen when a hollow tube carrying the torque from 1150 HP in walls .020" thick at 3,000 RPM, carefully balanced and tuned to avoid resonances, is holed or furrowed by a 7.7MM round, upsetting all that balancing and tuning? I suspect the shaft would shake itself loose, possibly ripping the intermediate coupling loose from its supporting structure.

Actually, it is. Imagine you're in a dogfight, pulling 3,000 RPM and all the MP the supercharger will give you, plus fluctuating G and gyroscopic loads from your gyrations, and your reduction gearbox is disabled, suddenly unloading that engine right behind your seat. Wide open throttle and no load on the crankshaft, what do you think is going to happen? Right, it's going to come unglued. Spectacularly. The only question is how many revs it'll hit before it does. 3,500? 4,000? Who cares? You won't. The scalding glycol and engine oil will have seen to that. And nobody will be around to tell the tale.
Reduction gearbox armor was essential.[/QUOTE]

I disagree.

Because the drive shaft is supported front and midsection by the main structural beam of the aircraft. 

Because if your "I KNOW" scenarios were true, EVERY Sikorsky helo would have had that problem; radial engine with drive shaft going through the cabin.

So, once again, show me some documentation OTHER THAN "Oh, I KNOW."

I'm still waiting.

As for hot glycol, that is BELOW and BEHIND the pilot int the P-39;

Perhaps you are confused by the P-40, with the coolant and oil radiators in front of the pilot, where one little bullet could scald him?
Then the P-40 was a deathtrap! It should have had foot-thick armor in front of those radiators!


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## P-39 Expert (Jan 13, 2021)

I'll s


jmcalli2 said:


> I got my engine model info from USAF Engine Models
> 
> The chart does not say how many of a specific model carried the specified engine; could be one, could be more of the production run.


I'll stick with my answer.

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## GrauGeist (Jan 13, 2021)

jmcalli2 said:


> Because the drive shaft is supported front and midsection by the main structural beam of the aircraft.


Nothing supported the drive shaft between the engine and gearbox except the carrier bearing assembly that was situated at the 60" mark, where the two shafts joined.


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## tyrodtom (Jan 13, 2021)

jmcalli2 said:


> Again YOU HAVE NO IDEA WHAT THE CONVERSATION IS ABOUT!
> 
> It is about the armor in front of the gearbox.
> 
> ARMOR THAT WOULD NOT STOP A 20mm SHELL.



I'm beginning to wonder if you do.
I'm pointing out that .30 caliber proof armor is minimum armor, no aircraft I'm aware of carried a smaller caliber weapon, while almost any axis aircraft you would meet ( with the exception of the Ki-43 early in the war) had additional guns that were bigger than .30 cal. 
So just what good did the armor do?
What Larry Bell did IMO was create a aircraft that was so different from other aircraft it was dangerous.
Right at the end of a combat mission when the ammo is low or out, and the pilots flying skills aren't the best because he's probably dog tired.
Most aircraft handle the best at the end of the flight, if there's no battle damage, lower total weight, lower stalling speed, etc.
But in the P-39's case that's when it's most sensitive, with close to aft CG.
Pull that turn to final a little too tight, or rough, and you'll end up in a stall/spin that'll take more altitude to recover from than you've got. 

Most aircraft destroyed in combat in the WW2 era would get no investigation under most conditions.
The pilot, if he survived, sometimes might have a clue. His squadron friends might see it, but are likely too busy with the mission, or their own survival , to really concentrate on exactly what happened.
And even if they could find a secure crash site, no one had the time to do a complete forensic investigation on a smoking hole in the ground, like modern crash investigations .

I feel like this is a waste of time trying to have a adult conversation with someone who evidently has no knowledge beyond what he reads, and has no real experience with anything mechanical.


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## GregP (Jan 13, 2021)

The P-39L was built with both -63 and -83 engines. Basically, the P-39L was a P-39K with a Curtiss Electric propeller and a modified nosewheel.

The -63 has 7.48 : 1 supercharger gearing. It had 1325 hp at S.L. and 1100 hp at 13,800 ft and 44.2 in. Hg.

The -83 had 9.60 : 1 supercharger gearing. It had 1200 hp at S.L. and 1125 hp at 15,500 ft. and 38.8 in. Hg.

Both airplanes were likely flown at considerably higher power settings than 39" - 44" Hg by the Soviets, so they likely got sprightly performance that another 300 - 400 hp would offer.

So, the -63 was better way down low and the -83 was better a couple of thousand feet higher than the -63 airplane ... but neither one should have had a decisive difference in flight performance except for shorter takeoff in the -63 airplane and slightly better very low-altitude climb performance.

In service, there was no problem with drivehsaft failures. There wll might have been combat drivehsaft failures, but there were NONE in-service in airplanes that returned from combat.


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## GrauGeist (Jan 13, 2021)

Interesting - I've seen photographs and guncam footage showing aircraft being attacked and in the process, engines falling away, landing gear dropping, control surfaces flying off, canopy structures blown out and a whole host of other indications of deadly fire.

But aparently Bell was a genius and built an indestructible machine that can defy the laws of physics...


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## XBe02Drvr (Jan 14, 2021)

jmcalli2 said:


> Perhaps you are confused by the P-40, with the coolant and oil radiators in front of the pilot, where one little bullet could scald him?
> Then the P-40 was a deathtrap! It should have had foot-thick armor in front of those radiators!


The P40 had a firewall between the propulsion compartment and the rest of the airframe, as front engine planes generally do. They are made of stainless steel, ruggedly constructed to take the stresses of the engine mounts bolted to them, and generally do their job well, keeping engine related fluids and risks out of the rest of the plane. Anyone who's had grease under their fingernails from working on airplanes knows this.



jmcalli2 said:


> As for hot glycol, that is BELOW and BEHIND the pilot int the P-39;


In all the drawings and photos I've seen of P39s in service, being maintained, or under construction, there doesn't seem to be any sort of a solid secure firewall between the engine compartment and the cockpit, and the radiator and oil cooler plumbing run right under the pilot's feet. The engine mounts appear to be supported by the lower fuselage "backbone" beams rather than cantilevered from a firewall in the usual manner. This means that cockpit and engine compartment form a cocoon that will confine and contain any escaped hot fluids, frying the pilot. Not my favorite way to go.


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## P-39 Expert (Jan 14, 2021)

GregP said:


> The P-39L was built with both -63 and -83 engines. Basically, the P-39L was a P-39K with a Curtiss Electric propeller and a modified nosewheel.
> 
> The -63 has 7.48 : 1 supercharger gearing. It had 1325 hp at S.L. and 1100 hp at 13,800 ft and 44.2 in. Hg.
> 
> ...


The -63 engine had the same 8.8 supercharger gears as the -35. The 7.48 geared engines were all two stage.

The 9.6 engines developed the same 1150HP as the 8.8 engines, just at about 3000ft higher critical altitude. At the same altitude, the 9.6 engines developed about 100HP more than the 8.8 engines above about 9000ft. Gave the P-39N a big performance edge over the D/F/K/L at the same weights. See attached chart. 

I don't know of any L models with the -83 engine, otherwise they would be Ms.

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## P-39 Expert (Jan 14, 2021)

tyrodtom said:


> I'm beginning to wonder if you do.
> I'm pointing out that .30 caliber proof armor is minimum armor, no aircraft I'm aware of carried a smaller caliber weapon, while almost any axis aircraft you would meet ( with the exception of the Ki-43 early in the war) had additional guns that were bigger than .30 cal.
> So just what good did the armor do?
> What Larry Bell did IMO was create a aircraft that was so different from other aircraft it was dangerous.
> ...


The slightly aft CG after ammunition was expended did not affect approach or landing. Or any normal maneuvers for that matter, just post-stall. P-39 was as safe as any other AAF fighter.


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## tyrodtom (Jan 14, 2021)

jmcalli2 said:


> It wouldn't need to. What's going to happen when a hollow tube carrying the torque from 1150 HP in walls .020" thick at 3,000 RPM, carefully balanced and tuned to avoid resonances, is holed or furrowed by a 7.7MM round, upsetting all that balancing and tuning? I suspect the shaft would shake itself loose, possibly ripping the intermediate coupling loose from its supporting structure.
> 
> Actually, it is. Imagine you're in a dogfight, pulling 3,000 RPM and all the MP the supercharger will give you, plus fluctuating G and gyroscopic loads from your gyrations, and your reduction gearbox is disabled, suddenly unloading that engine ri





P-39 Expert said:


> The slightly aft CG after ammunition was expended did not affect approach or landing. Or any normal maneuvers for that matter, just post-stall. P-39 was as safe as any other AAF fighter.



Sometimes landings can get a little more extreme than you seem to think, more accidents happen during landing than any other normal flight operation. 
You can choose when to take off, but when landing you have to accept whatever the weather is, and your decision might be pressured by fuel shortage, then add in a tired pilot.


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## GregP (Jan 14, 2021)

Regarding post 898, Graugeist, I assume you're just being sarcastic.

Other airplanes had engines mounted in engine mounts that were attached to the firewall and airframe. A few well-placed, or badly-placed depending on how you look at it, shots could essentially remove an engine mount. Especially cannon shots. The engine could depart the airframe in those cases, along with other bits and pieces that were attached to the engine somehow. We've all seen it in gun cam clips.

In the P-39, the engine was mounted to the center of the fuselage. To make the engine drop away from the airpolane, you'd have to blow the airplane in half. I'm sure that happened in combat at some point, but it didn't return from combat if it was blown in half, so there isn't a recorded driveshaft failure for it. Nobody said there wasn't driveshaft damage, what they said was therre was no recorded driveshaft failure in planes that returned from combat. There well might be and likely were driveshaft failures in airplanes that went down in combat. I'd be very surprised if there weren't, but the driveshaft was not a problem failure point for the airplane or even a blip on the chart of issues.

That doesn't magically make the P-39 a better airplane. All it means is that the driveshaft was not an issue. There were plently of other issues with the P-39, as we have expounded upon at length in the groundhog thread.

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## XBe02Drvr (Jan 14, 2021)

P-39 Expert said:


> *The slightly aft CG after ammunition was expended did not affect approach or landing. *Or any normal maneuvers for that matter, just post-stall. P-39 was as safe as any other AAF fighter.


*BULLPUCKY!* Even a docile, user friendly airplane like a Cessna 150 or Piper Warrior, or even a Beech T34 stalls more suddenly, more violently and less predictably when loaded to its aft CG limit. I used to explore this with my students, knowing that most of their future recreational and/or professional flying would be done in aft loaded planes, unlike the forward loaded scenario that prevails in training flights. We would do a careful W&B calculation, then ballast the aft baggage space to put the CG right at the aft limit at the worst case scenario for the flight, as some planes shift CG aft with fuel burn. Sometimes this would entail calculating how far forward of the aft limit we would have to set the CG to not go out of limit during the time of the lesson. A good exercise for a student who you know is going to take the family out for a ride as soon as the ink is dry on their license.
As CG approaches aft limit, stick force gradient gets lighter and lighter, and the tendency to over control increases exponentially. The last few degrees of angle of attack come much faster than expected, you get a brief "bleep" of the stall horn, and WHAM!, the nose and one wing drop sharply, your stomach tries to egress through your esophagus, and the windshield is full of trees. Not the gentle "rocking chair ride", easily controllable stall you've become accustomed to in your docile pussycat airplane. The key here is unpredictability: when it will occur, the minimal to non-existent warning, and the asymmetry of the stall break.
Now translate this to a mid-engine, high performance, high wing loading fighter plane with reduced inherent stability, a propensity for aft CG loading, and an acknowledged out-of-AAF-spec super light stick force gradient, and the assertion that approach and landing at aft CG limit (or perhaps beyond it) were "normal" is pretty hard to swallow.
Even in light, stable, easy-to-fly GA airplanes, it's not the set piece straight and level stall that will kill you; it's the descending, turning, close to the ground stall that sneaks up on you and bites you in the ass. Exponentially more so with higher performance aircraft.
And still, terrestrial aviation hasn't embraced the AoA indicator, something the sea services have been relying on for over a half century.

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## GrauGeist (Jan 14, 2021)

GregP said:


> Regarding post 898, Graugeist, I assume you're just being sarcastic



No sarcasm - I just recently watched some Luftwaffe guncam footage and in one segment, a Bf110G-2 closed in a B-24 and tore it apart, literally. The inboard engine on the starboard wing tumbled free after cannon hits. It was horrible to see.

There's other instances, but this shows that an aircraft under fire is subject to damage - in some cases, catastrophic damage.

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## Tord55 (Jan 14, 2021)

swampyankee said:


> P-61A:
> 
> Eliminate the gunner and the turret. Put the pilot and radar operator under a tandem canopy, that is jump right to the P-61E configuration. Getting rid of the turret and gunner would probably save close to a ton in empty weight, twenty percent in zero-lift drag, and months in development



Tandem-seating has proved over and over as draggier than side by side (see Hawker Hunter, Skyraider, and many more). The ideal in sub-sonic speeds are quite corpulent fuselages unless we are talking laminar flow, at transonic speeds.


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## tyrodtom (Jan 14, 2021)

I about got caught by a stall on final in a Piper Cherokee.
Cross wind , turned from base to final a little late, tightened the turn too much to try and line up with the runway.
Horn went off, aircraft shook a little, and I eased out of the bank, put the nose down a little, then lined up late on final. 
I almost landed short. A experienced pilot who observed my landing was pretty critical of my performance.

I should have aborted that landing and went around.
That's same scenario has killed a lot of people.

If I had had two people in the rear seat, and luggage, I probably would have not have had enough control authority to ease the bank, or lower the nose.

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## Tord55 (Jan 14, 2021)

PAT303 said:


> I would have liked to have seen the Spit reach it's full potential. The interim models were needed, MkV-IX-XIV but I can't help but think the blooding of the spit in 1941-42 by the likes of the FW190A would not have happened if the MkIII running 2 stage Merlin XX's could have been made.



Bigger, better flaps would have made a hell of a change, too!


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## BiffF15 (Jan 14, 2021)

P-39 Expert said:


> The slightly aft CG after ammunition was expended did not affect approach or landing. Or any normal maneuvers for that matter, just post-stall. P-39 was as safe as any other AAF fighter.



P39Expert,

If the P-39 was as safe as other fighters why did it have a reputation for tumbles / squirrely handling, or why did the USAAF do a spin demo film on it AND show one crash?

Hint: the crash was at the end as a punctuation point to the novice fighter pilots, a poke in the chest if you will.

Just because a person repeats something DOESN’T make it true no matter how many times it’s said.

Also realize there are actual experienced pilots on here who can and do refute erroneous statements so please don’t take it personal.

V/R,
Biff


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## P-39 Expert (Jan 14, 2021)

BiffF15 said:


> P39Expert,
> 
> If the P-39 was as safe as other fighters why did it have a reputation for tumbles / squirrely handling, or why did the USAAF do a spin demo film on it AND show one crash?
> 
> ...


Biff, if I took any of this personal then I wouldn't continue to post on this board. 

Virtually every AAF pursuit pilot trained on a P-39. If they were as dangerous as some on here claim then their role as trainers would have been curtailed. It wasn't. Chuck Yeager's favorite plane (until he got a Merlin P-51). He also said he didn't know anyone who didn't like the the P-39, and all the people who made those adverse claims had never flown a P-39. That includes the pilots who post on here. 

And deliberate spinning was prohibited in virtually every AAF pilot's manual. The magnificent Merlin P-51 was a bitch in a spin too.

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## XBe02Drvr (Jan 14, 2021)

P-39 Expert said:


> If they were as dangerous as some on here claim then their role as trainers would have been curtailed. It wasn't.


It wasn't, because training command P39s were ballasted to keep CG away from the limits of the envelope, and didn't need as much aft mounted radio gear as combat zone planes did. This still didn't keep it from acquiring a "weirdo" rep amongst the pilots, as its ergonomics, its "feel", its handling, and especially its operating speeds were so different from the AT6s they were used to. Chuck Yeager was that rare nugget: a gifted "natural" from the get-go, who had the analytical mind, the disciplined approach, the confidence, and the reflexes and vision to quickly master a plane, and once past its quirks, appreciate its potential. Not a representative sample. I'm sure he appreciated its "hotrod" nature vs the Texan he'd been flying, and revelled in it, rather than be intimidated by it.
Ever wonder why so many P39s were stateside as fighter trainers when so many fighters were needed in combat theatres? They weren't actually optimum for the job, as their handling characteristics were so different from the advanced trainers and frontline fighters the students had come from and would go to, but they were available stateside, while every P40, and later P47 and P51, was urgently needed for combat. Makes you wonder, doesn't it?


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## P-39 Expert (Jan 14, 2021)

XBe02Drvr said:


> It wasn't, because training command P39s were ballasted to keep CG away from the limits of the envelope, and didn't need as much aft mounted radio gear as combat zone planes did. This still didn't keep it from acquiring a "weirdo" rep amongst the pilots, as its ergonomics, its "feel", its handling, and especially its operating speeds were so different from the AT6s they were used to. Chuck Yeager was that rare nugget: a gifted "natural" from the get-go, who had the analytical mind, the disciplined approach, the confidence, and the reflexes and vision to quickly master a plane, and once past its quirks, appreciate its potential. Not a representative sample. I'm sure he appreciated its "hotrod" nature vs the Texan he'd been flying, and revelled in it, rather than be intimidated by it.
> Ever wonder why so many P39s were stateside as fighter trainers when so many fighters were needed in combat theatres? They weren't actually optimum for the job, as their handling characteristics were so different from the advanced trainers and frontline fighters the students had come from and would go to, but they were available stateside, while every P40, and later P47 and P51, was urgently needed for combat. Makes you wonder, doesn't it?


Yes I really do wonder. Half of them went to the Soviets where they won the war and the other half were used as trainers here. And ANY combat plane would be a major step up from an AT-6 Texan.

You can keep grasping for any straw and rumor to somehow make the P-39 a deathtrap, but in reality it was a very serviceable combat plane. Do you consider the F6F Hellcat to be a good plane? Scourge of the Japanese and kings of the Pacific. Shot down more Japanese aircraft than any other plane. Look at the attached graph (wwiiaircraftperformance.org) with P-39N performance overlayed in red. Pretty competitive, no? And consider that the P-39N was out of production before the Hellcat had it's first combat with the USN.


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## PAT303 (Jan 14, 2021)

GrauGeist said:


> No sarcasm - I just recently watched some Luftwaffe guncam footage and in one segment, a Bf110G-2 closed in a B-24 and tore it apart, literally. The inboard engine on the starboard wing tumbled free after cannon hits. It was horrible to see.
> 
> There's other instances, but this shows that an aircraft under fire is subject to damage - in some cases, catastrophic damage.



Plus you need to add the aerodynamic loading G forces etc, there are many video's of aircraft being hit while turning hard and suddenly having a wing fold or pitch up into a stall and drop like a lead fart, as a former heavy vehicle mechanic I didn't see many driveshaft failures but when it did happen the damage was catastrophic, having a universal joint fail while hauling a load at very slow speed, like pulling away from the lights meant the engine immediately redlined and the tail shaft thrashed the underside to pieces, the energy released and the damage it causes has to be seen to be believed, I cannot image an aircraft can go through an entire war with a 12' driveshaft through it's middle not having a failure, whether by mechanical failure or by battle damage, the shaft is simply to big a component to not be hit by enemy fire.

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## PAT303 (Jan 14, 2021)

XBe02Drvr said:


> while every P40, and later P47 and P51, was urgently needed for combat. Makes you wonder, doesn't it?



That one line describes the P-39, if it was such a war winner why didn't it go to war?

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## GrauGeist (Jan 14, 2021)

Bill Overstreet (P-51C pilot) absolutely hated it.

And in a twist of irony, the only American P-39 ace, Bill Fiedler, was killed by a P-38 - while sitting in the cockpit of his P-39 on the ground.

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## swampyankee (Jan 14, 2021)

The P-39 and P-63 _did_ go to war, it's just that the war they seemed to be good at fighting wasn't the war that the US or Commonwealth were fighting. In the Pacific, it really didn't have the range (or carrier compatibility) to be much use in the island-hopping campaigns and its range may have been an issue with its lack of use in the China-Burma-India theatre. It's also entirely possible that it, like some other aircraft, was competitive against German aircraft but struggled against the Japanese ones.

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## Milosh (Jan 14, 2021)

P-39 Expert said:


> Yes I really do wonder. Half of them went to the Soviets where they won the war and the other half were used as trainers here. And ANY combat plane would be a major step up from an AT-6 Texan.


The AT-6 wasn't exactly a docile a/c.

Talk to ten different people with first-hand knowledge of a particular aircraft and you get ten different accounts of the same aircraft. Not so with the T-6 "Texan". All agree the Texan had some terrible flight characteristics (fairly normal for a low wing monoplane of the mid 30's),


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## GrauGeist (Jan 14, 2021)

The AT-6 (aka T-6/Harvard/SNJ/etc.) has quite a legacy for a 1930's aircraft, being used by dozens of nations for everything from training to combat, finally being retired by several air forces in the 1990's.

Not many interwar aircraft types can lay claim to that notoriety.

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## swampyankee (Jan 14, 2021)

Tord55 said:


> Tandem-seating has proved over and over as draggier than side by side (see Hawker Hunter, Skyraider, and many more). The ideal in sub-sonic speeds are quite corpulent fuselages unless we are talking laminar flow, at transonic speeds.



The problem with the P-61 wasn't tandem vs side-by-side seating, it was that the center nacelle was sized for three crew members and a bulky turret. The P-61E/F-15 nacelle was significantly smaller than that of the other P-61 models.


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## BiffF15 (Jan 14, 2021)

P-39 Expert said:


> Yes I really do wonder. Half of them went to the Soviets where they won the war and the other half were used as trainers here. And ANY combat plane would be a major step up from an AT-6 Texan.
> 
> You can keep grasping for any straw and rumor to somehow make the P-39 a deathtrap, but in reality it was a very serviceable combat plane. Do you consider the F6F Hellcat to be a good plane? Scourge of the Japanese and kings of the Pacific. Shot down more Japanese aircraft than any other plane. Look at the attached graph (wwiiaircraftperformance.org) with P-39N performance overlayed in red. Pretty competitive, no? And consider that the P-39N was out of production before the Hellcat had it's first combat with the USN.



P39 Expert,

Okay, the P39 versus F6F comparison is really not that good. 
A. The P39 wasn't carrier capable, wasn't able to carry the bomb load, nor did it make as many aces as did the F6F. 
B. Range? 
C. Grumman was known for making great flying planes. Did the F6F have any problems qualifying on the carrier, did the guys complain about it biting them in any manner similar to what the P39 experienced? The F6F was a large plane due to performance requirements as well as carrier operations imposed weight penalties. 

Guys have spent a LARGE amount of time on here trying to show you where you are making assumptions that are not correct, or coming to conclusions based on incomplete or incorrect data.

Your ability to ignore facts, or information you don't agree with is TREMENDOUS.

Good luck.

V/R,
Biff

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## jmcalli2 (Jan 14, 2021)

GrauGeist said:


> Nothing supported the drive shaft between the engine and gearbox except the carrier bearing assembly that was situated at the 60" mark, where the two shafts joined.



So, you have no understanding of the structure of the P-39.
So either read up on it or please go to a different topic.


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## jmcalli2 (Jan 14, 2021)

tyrodtom said:


> I'm beginning to wonder if you do.
> I'm pointing out that .30 caliber proof armor is minimum armor, no aircraft I'm aware of carried a smaller caliber weapon, while almost any axis aircraft you would meet ( with the exception of the Ki-43 early in the war) had additional guns that were bigger than .30 cal.
> So just what good did the armor do?
> What Larry Bell did IMO was create a aircraft that was so different from other aircraft it was dangerous.
> ...



So, your argument is the same as the P-51 time warp story.

Entirely in your head.


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## jmcalli2 (Jan 14, 2021)

XBe02Drvr said:


> The P40 had a firewall between the propulsion compartment and the rest of the airframe, as front engine planes generally do. They are made of stainless steel, ruggedly constructed to take the stresses of the engine mounts bolted to them, and generally do their job well, keeping engine related fluids and risks out of the rest of the plane. Anyone who's had grease under their fingernails from working on airplanes knows this.
> 
> 
> In all the drawings and photos I've seen of P39s in service, being maintained, or under construction, there doesn't seem to be any sort of a solid secure firewall between the engine compartment and the cockpit, and the radiator and oil cooler plumbing run right under the pilot's feet. The engine mounts appear to be supported by the lower fuselage "backbone" beams rather than cantilevered from a firewall in the usual manner. This means that cockpit and engine compartment form a cocoon that will confine and contain any escaped hot fluids, frying the pilot. Not my favorite way to go.




So you didn't bother to read the design analysis I posted hear.

Sorry for your loss.


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## GrauGeist (Jan 14, 2021)

jmcalli2 said:


> So, you have no understanding of the structure of the P-39.
> So either read up on it or please go to a different topic.


You and your smartass comments are growing tiresome.

Any halfwit can look at a P-39's cutaway and see CLEARLY that the driveshaft is NOT SUPPORTED by any other means than the 1) Engine Output, 2) Carrier bearing assembly at the coupling (at the halfway point) and finally, 3) Gearbox situated at the nose. It was a 102 inch spinning shaft - it wasn't going to be attached to anything other than components that required it's energy transfer.

Perhaps you should go look under your car for a rudimentary idea of what the grownups are talking about here, or find a topic better suited to your limited abilities.

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## XBe02Drvr (Jan 15, 2021)

jmcalli2 said:


> So you didn't bother to read the design analysis I posted hear.
> 
> Sorry for your loss.


A couple of the attachments people put up on this thread refused to open on my Android, but I haven't seen anything contradicting what I posted. Explain yourself.

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## XBe02Drvr (Jan 15, 2021)

P-39 Expert said:


> Yes I really do wonder. Half of them went to the Soviets where they won the war and the other half were used as trainers here.





swampyankee said:


> The P-39 and P-63 _did_ go to war, it's just that the war they seemed to be good at fighting wasn't the war that the US or Commonwealth were fighting.


Yup, we in the west just couldn't come up with a theater of operations suited to the Airacobra's rather limited advantages, so we made trainers out of them.

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## XBe02Drvr (Jan 15, 2021)

GrauGeist said:


> Perhaps you should go look under your car for a rudimentary idea of what the grownups are talking about here, or find a topic better suited to your limited abilities.


He probably has a front wheel drive and will miss your point entirely.

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## nuuumannn (Jan 15, 2021)

Simon Thomas said:


> The Royal Australia Navy wanted to buy helicopters, and then drowned them in specifications to the extent that they were incapable of entering service.



And now we (the Royal New Zealand Air Force) have them! 



Simon Thomas said:


> I have read a few books on the Stirling, and there is no clear answer however most point to the Air Ministry using it to limit the all up weight. Which is rather ironic, considering the plethora of mandatory requirements which drove the weight so high in the finished product.



Part of the problem with the Stirling was that construction of the prototype was begun before trials with the small scale aircraft had been completed, which meant Short didn't foresee that the wing's angle of incidence was too shallow, which meant it would have had an inordinately long take off run fully loaded, so its gangly undercarriage was lengthened to steepen the angle at which the wing began to produce adequate lift to get the thing off the ground.

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## XBe02Drvr (Jan 15, 2021)

nuuumannn said:


> Short didn't foresee that the wing's angle of incidence was too shallow, which meant it would have had an inordinately long take off run fully loaded


The commuter airline I worked for had a couple Short SD30s. They were real ground lovers, too. You could tell they were designed and built by shipyard people. The front office was more like a ship's bridge than an airplane's cockpit. Crews called it "the wheelhouse".


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## nuuumannn (Jan 15, 2021)

XBe02Drvr said:


> The commuter airline I worked for had a couple Short SD30s.



I used to know a Short 360 driver who called it the Short Shed.

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## GrauGeist (Jan 15, 2021)

XBe02Drvr said:


> He probably has a front wheel drive and will miss your point entirely.


Damn...didn't think about that.

I figured the lack of reply was because he was trying to find a cutaway where the driveshaft itself was physically bolted to the center frame...


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## GregP (Jan 15, 2021)

Regarding post 912: Hi P-39 Expert.

The F6F flew 66,530 action sorties for the Navy, claimed 5,163 enemy aircraft shot down, and had 2,461 combat losses, only 270 of which were to enemy aircraft. That averages out to one kill every 13 action sorties. It was the first USN fighter to be able to outclimb the A6M Zero and almost turn with one. It was VERY forgiving and was called the Ace-maker. The kill to loss ratio was 19.12 : 1 for air-to-air and 2.09 : 1 overall if you figure in ALL losses, which is not generally done.

The P-39 flew zero action sorties, had no kills, and no losses in US Navy service.

In USAAF service, it flew 30,547 combat sorties, had 14 air kills and 18 ground kills claimed, had handling quirks that made it a plane nobody wanted to fly in combat. It was nicknamed the Peashooter by pilots becasue of its ineffectivness in combat. It had 107 combat losses, but the USAAF doesn't tell us how many were air-to-air and how many were ground. I can't tell you if the losses were air-to-air or total. That averages out to one kill every 955 combat sorties if you use the total and 1 kill every 2,182 sorties if you take air-to-air kills. The kill to loss ratio was .13 : 1 for air kill and .30 : 1 for all kills. I don't know the makeup of the losses.

When I compare 1 kill every 13 sorties to 1 kill every 955 sorties or 1 kill every 2,182 sorties for air kills (for overall kill-to-loss ratio), and 19.12 : 1 for air kill to 0.13 : 1 for air kills, I have a definite preference for which airplane I'd choose to fly in combat. It ain't exactly a tough choice. Give me the Ace-maker every time.

If you can’t see a huge difference in that combat performance, you are blind and fail to realize it. That performance was over the entire population of F6Fs in US service and the vast majority of the USAAF P-39s in Pacific service, which is where we mostly used them. So, both are pretty valid statistical comparisons for airplanes in US service in the Pacific. If you can find the numbers for the P-39 in Soviet service that are from a primary source and not some Russian forum with no references to sources, please share them. I can't find them myself to date.

The Soviet Union fought a low-altitude war and had no restrictions on engine boost. That allowed them to get good performance from the P-39 in a very low-altitude environment that happened to be right where the P-39's strength was. The U.S.A. didn’t fight in a low-altitude environment that favored the P-39 and didn’t get the performance from the P-39 that the Russian got because we flew by a very different book that was effective in the war WE fought.

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## Milosh (Jan 15, 2021)

Not the best. scroll down
The Modelling News: Kittyhawk’s new Airocobra makes it's first built up debut...


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## P-39 Expert (Jan 15, 2021)

BiffF15 said:


> P39 Expert,
> 
> Okay, the P39 versus F6F comparison is really not that good.
> A. The P39 wasn't carrier capable, wasn't able to carry the bomb load, nor did it make as many aces as did the F6F.
> ...


Agree that the Hellcat was a carrier plane and the P-30 was a land based plane. But like most of my assertions this graph is based solely on facts. Nothing but facts from sources like wwiiaircraftperformance.org and AHT. Official tests conducted by the Navy and Wright Field. The P-39N outperformed the F6F by a substantial margin. This is not an assumption but a fact.

Why can't you, like most on this board, just admit that you had not seen the P-39 performance tests on wwiiaircraftperformance.org? Admittedly the information was not posted on the site until 2012. This is well after most all the reference books on WWII fighters were published, including AHT, the William Green books, etc. All the reference material you have seen on the P-39 is basically wrong/out of date based on those tests. 

I have made very few assumptions on here, just results of official military tests. The rest of you guys are the ones who deal in heresay, like tumbling, symmetrical airfoils, the driveshaft breaking, ets. That is all based on heresay and conjecture. Go look at the facts.


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## P-39 Expert (Jan 15, 2021)

GregP said:


> Regarding post 912: Hi P-39 Expert.
> 
> The F6F flew 66,530 action sorties for the Navy, claimed 5,163 enemy aircraft shot down, and had 2,461 combat losses, only 270 of which were to enemy aircraft. That averages out to one kill every 13 action sorties. It was the first USN fighter to be able to outclimb the A6M Zero and almost turn with one. It was VERY forgiving and was called the Ace-maker. The kill to loss ratio was 19.12 : 1 for air-to-air and 2.09 : 1 overall if you figure in ALL losses, which is not generally done. *Hellcat was a great plane, the best Navy fighter in WWII.*
> 
> ...



Please expand above.


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## Milosh (Jan 15, 2021)

P-39Q
service ceiling: 34,900 (100fpm)
absolute ceiling: 35,700 (0fpm)

spin tests, Report on Spin Tests, P-39Q (wwiiaircraftperformance.org)

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## XBe02Drvr (Jan 15, 2021)

Milosh said:


> P-39Q
> service ceiling: 34,900 (100fpm)
> absolute ceiling: 35,700 (0fpm)
> 
> spin tests, Report on Spin Tests, P-39Q (wwiiaircraftperformance.org)


Note: This spin test was conducted with CG well forward (28.8% MAC) of the aft limit (31% MAC) that would be approached by a combat equipped P39 with ammunition expended.

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## Shortround6 (Jan 15, 2021)

P-39 Expert said:


> Agree that the Hellcat was a carrier plane and the P-30 was a land based plane. But like most of my assertions this graph is based solely on facts. Nothing but facts from sources like wwiiaircraftperformance.org and AHT. Official tests conducted by the Navy and Wright Field. The P-39N outperformed the F6F by a substantial margin. This is not an assumption but a* fact*.
> 
> Why can't you, like most on this board, just admit that you had not seen the P-39 performance tests on wwiiaircraftperformance.org?



Facts
1. The P-39N was running clean except for the drop tank shackle (no sway braces).
2. The F6F-3 was running with fuselage bomb rack and "T" braces, also wing bomb rack fairings and sway braces. In Clean condition the F6F-3 was supposed to be good for 321mph at sea level and 384mph at 18,000ft, not the 372mph shown on the chart. 
3. The P-39N was running light. 3-400lbs below normal clean gross weight. Reduced fuel? 
4. The F6F-3 is rated at full clean gross weight. Full internal fuel.
5. A minor consideration. (sarcasm) the P-39N was running above (well above?) the the AIr Corp standards for cooling temperatures. 
6. This P-39N seems to show an _amazing_ deviation from other P-39s. Performance at 5,000ft
.......................................P-39M.........................P-39N........................P-39Q 
Weight...........................7430lbs.........................7301lbs.....................7871lbs
Horsepower..................1395.............................1375............................1382
Climb ft/min.................3840..............................4240...........................3770
Speed at 9,500ft..........385.5............................398.4*.........................374
All at 57in MAP and 3000rpm except the speed of the P-39N.
P-39N used 59.8in MAP at 9700ft. 

P-39Q speed was at 10,000ft. P-39Q had the under wing gun pods.
Notes the test of the P-39-Q-5 (different pane than above) state that the external gunpods on the XP-63 were worth about 110ft/min climb. This was noted as the test P-39Q-5 engine was not running properly and so could not be compared to the P-39Q-1 test. 

Yep, let's pick and choose our facts _very, very_ carefully and then accuse others of being unaware or failing to see the brilliance of the concept. 

rapid climb by P-39 ending with overheated engine in tropical/desert conditions. Great way to start combat, engine already cooking itself. 

I would really love to see the different P-39 model's performance on a chart as I think this P-39N would be in a class by itself.

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## GregP (Jan 15, 2021)

Regarding post #935 ... I think not. The point was made very clearly.


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## Shortround6 (Jan 15, 2021)

I would like to note another "FACT".

The P-39N test was test of a single airplane.

The F6F-3 data is from an Airplane Characteristics and Performance sheet (multiple) used for mission planning. 
In other words every plane (or most) in the unit had to meet those numbers. Yes they were based on tests but using best numbers means some planes might not make it home due to running out of fuel.


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## GregP (Jan 15, 2021)

When I was in the military weapons business, the MINIMUM testing we did was five units. Then we'd throw out the high and low readings, and average the other three. Mostly, it was more units than five, sometimes ten or fifteen. That was non-destructive testing.

For destructive testing, the number of units expended was dependent upon cost. One doesn't fire ten Navy Standard Missiles just to check performance. But bench-tesing the proximity fuze was non-destructive and could be run as many times as you wanted, and the test unit could still be delivered to the fleet.

Also, Shortround6, by the time the P-39N came along, the P-39's reputation in the USAAF was already well established, and making it sound better wasn't going to work with the rank and file pilots. They already knew people who had flown them, and they had their opnions. Forcing P-39s on them wasn't gling to help morale. The first time a P-39N shows up is Nov 42, and pilot morale was IMPORTANT at that time. Also, the P-39N had a smaller fuel tank that decreased the already-too-short range. Nov 42 was contemporary with the Fw 190A-5 and the P-40M.

The P-40M was basically a purely export version of the P-40K although many ended up in US units. The Allison had 1,325 hp and gave noticeably better performance than the P-40E, particularly at low altitudes. The Fw 190A-5 needs no introduction; it was one of the finest fighters at the time, if not the BEST. If you had a choice, almost everyone would choose the Fw 190 or the P-40 over the P-39N, if only from reputation.

The P-40 flew 67,059 sorties and had 521 claimed kills against 553 combat losses. That in the ETO. That's 1 kill every 129 sorties. Much better than the P-39's 1 kill every 955 sorties.

Update from above: My P-39 numbers were from the ETO 1942 - 1945, not the Pacific, as are the P-40 numbers above.

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## P-39 Expert (Jan 15, 2021)

Shortround6 said:


> Facts
> 1. The P-39N was running clean except for the drop tank shackle (no sway braces). *Correct. *
> 2. The F6F-3 was running with fuselage bomb rack and "T" braces, also wing bomb rack fairings and sway braces. In Clean condition the F6F-3 was supposed to be good for 321mph at sea level and 384mph at 18,000ft, not the 372mph shown on the chart. *Agree. The F6F-5 chart showed 382mph top speed but 300fpm less climb. Take your pick, 10mph is negligible in the grand scheme of things.*
> 3. The P-39N was running light. 3-400lbs below normal clean gross weight. Reduced fuel? *Now don't act like you and I haven't beaten this to death in previous threads.  All the AAF fighters tested at less than published gross takeoff weight. All planes weigh less at the end of their mission than the start due to fuel burn. The test weight was the average weight of the plane for that flight. P-39 normally carried 720lbs internal, 360lbs is half. That's just how the AAF tested their planes. The British used a flat 95% of gross takeoff weight as tested weight. P-39N test 7274lbs divided by 95%=7656lbs, almost exactly gross weight. *
> ...



Please expand above.


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## P-39 Expert (Jan 15, 2021)

GregP said:


> When I was in the military weapons business, the MINIMUM testing we did was five units. Then we'd throw out the high and low readings, and average the other three. Mostly, it was more units than five, sometimes ten or fifteen. That was non-destructive testing.
> 
> For destructive testing, the number of units expended was dependent upon cost. One doesn't fire ten Navy Standard Missiles just to check performance. But bench-tesing the proximity fuze was non-destructive and could be run as many times as you wanted, and the test unit could still be delivered to the fleet.
> 
> ...


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## GregP (Jan 15, 2021)

So, pretty much the entire Allied aviaiton world thought the Fw 190 was the best fighter in the world when it came out, even the Spitfire V guys, but you are saying the P-39N was a match for it?

Am I interpreting that right? Just making sure before I reply to an incorrect assumption.

If you look at the Pilot's Operating Handbook for the P-39N-0 and N-1, the rate of climb at 3,000 rpm and 44.5" MAP (listed as Military Power), at 3,000 ft. and 5,000 ft. is shown as 2,250 fpm at 8,000 lbs gross weight and 2,900 fpm at 7,100 lbs. That won't outclimb an Fw 190A-5. This is from the Pilot's Operating Handbook straight from the USAAC.

The test in wwiiaricraftperformance are at 57" MAP. So, exactly WHEN did 57" MAP get approved? I don't know, but the coolant was overheating at this power setting, as indicated in the report. Definitely NOT as described in the Pilot's Operating Handbook, which is generally "the bible" on a military airplane.

Google P-39N POH pdf.

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## P-39 Expert (Jan 16, 2021)

GregP said:


> So, pretty much the entire Allied aviaiton world thought the Fw 190 was the best fighter in the world when it came out, even the Spitfire V guys, but you are saying the P-39N was a match for it? *A little slower at higher altitudes, better climb rate. P-39N had better performance than a Spitfire V.*
> 
> Am I interpreting that right? Just making sure before I reply to an incorrect assumption.
> 
> ...



Expand above.


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## GregP (Jan 16, 2021)

Yeah, right. Better than a Spitfire Mk.V. The numbers you are reporting are twice what is in the POH. Sorry, but another couple or three hundred hp just doesn't DO that, and neither did operational P-39s.

I'm not biting again for any reason. You're on your own. It's a good thing I'm not a moderator I suppose. Cheers.


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## P-39 Expert (Jan 16, 2021)

GregP said:


> Yeah, right. Better than a Spitfire Mk.V. The numbers you are reporting are twice what is in the POH. Sorry, but another couple or three hundred hp just doesn't DO that, and neither did operational P-39s.
> 
> I'm not biting again for any reason. You're on your own. It's a good thing I'm not a moderator I suppose. Cheers.


Just an official Wright Field performance test. What did they know?


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## Milosh (Jan 16, 2021)

*57" was WEP, you are looking at the WEP climb test. Right above that in wwiiaircraftperformance.org is the military power test at 50.5", which is what I used in the comparison.* 

P-39Q-5, AAF No. 42-19615 *57"* boost _4 August 1943_ 
P-39Q-5, AAF No. 42-19615 *55"* boost _9 October 1943_


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## P-39 Expert (Jan 16, 2021)

Milosh said:


> *57" was WEP, you are looking at the WEP climb test. Right above that in wwiiaircraftperformance.org is the military power test at 50.5", which is what I used in the comparison.*
> 
> P-39Q-5, AAF No. 42-19615 *57"* boost _4 August 1943_
> P-39Q-5, AAF No. 42-19615 *55"* boost _9 October 1943_



We're talking about the P-39N, not the P-39Q.


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## jmcalli2 (Jan 16, 2021)

GrauGeist said:


> You and your smartass comments are growing tiresome.
> 
> Any halfwit can look at a P-39's cutaway and see CLEARLY that the driveshaft is NOT SUPPORTED by any other means than the 1) Engine Output, 2) Carrier bearing assembly at the coupling (at the halfway point) and finally, 3) Gearbox situated at the nose. It was a 102 inch spinning shaft - it wasn't going to be attached to anything other than components that required it's energy transfer.
> 
> Perhaps you should go look under your car for a rudimentary idea of what the grownups are talking about here, or find a topic better suited to your limited abilities.



That bearing just sort of floats on air...

You morons have a problem.

You hate the P-39, but that's not your problem.

When someone posts documentation that the P-39 didn't suck, you go out of your way to invent "design flaws" that never existed.

When people post documentation that you were wrong, you say without evidence that people (such as the AAF flight test reports and designers such as Robert Woods and writers of the time like Martin Caidin and Eugene Miller) were wrong or lying.
Because you "KNOW!"

When asked to produce documentation of your positions, you change the subject or simply state, "I KNOW!"

Had you read ANYTHING about the P-39 structure, including the design analysis I posted, you would clearly see that "the airplane fuselage beam assembly was to all intents and purposes a part of the engine assembly since it was really a crank case extension and acted as a housing and support for the extension drive shaft and independent gear box assembly and propeller."

NONE of you have demonstrated ANY understanding of there P-39 structures. You even missed the fume-proof armor bulkhead that separates the cockpit from the gun compartment.

You don't understand the P-39 because your egos won't allow it.

When presented with documentation you turn off and fall back on "I KNOW!"

I know you.

And I feel sorry for you.


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## jmcalli2 (Jan 16, 2021)

XBe02Drvr said:


> A couple of the attachments people put up on this thread refused to open on my Android, but I haven't seen anything contradicting what I posted. Explain yourself.



Still waiting for ANY documentation from you...

You morons have a problem.

You hate the P-39, but that's not your problem.

When someone posts documentation that the P-39 didn't suck, you go out of your way to invent "design flaws" that never existed.

When people post documentation that you were wrong, you say without evidence that people (such as the AAF flight test reports and designers such as Robert Woods and writers of the time like Martin Caidin and Eugene Miller) were wrong or lying.
Because you "KNOW!"

When asked to produce documentation of your positions, you change the subject or simply state, "I KNOW!"

Had you read ANYTHING about the P-39 structure, including the design analysis I posted, you would clearly see that "the airplane fuselage beam assembly was to all intents and purposes a part of the engine assembly since it was really a crank case extension and acted as a housing and support for the extension drive shaft and independent gear box assembly and propeller."

NONE of you have demonstrated ANY understanding of there P-39 structures. You even missed the fume-proof armor bulkhead that separates the cockpit from the gun compartment.

You don't understand the P-39 because your egos won't allow it.

When presented with documentation you turn off and fall back on "I KNOW!"

I know you.

And I feel sorry for you.


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## buffnut453 (Jan 16, 2021)

My-oh-my, we're getting passionate about this topic! I'm pretty sure nobody on this forum "hates" any aircraft. We are all interested in learning more about aviation and to explore the reasons why things happened. 

Personally, I find it frustrating that the P-39 seems to crop up in every bluddy thread on this forum...and it's the same people having the same arguments on all the threads. Nobody's pre-existing perspectives are getting swayed by arguments in either direction. There's a lot of transmitting but not a lot of receiving going on. 

Frankly, it's getting boring.

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## P-39 Expert (Jan 16, 2021)

buffnut453 said:


> My-oh-my, we're getting passionate about this topic! I'm pretty sure nobody on this forum "hates" any aircraft. We are all interested in learning more about aviation and to explore the reasons why things happened.
> 
> Personally, I find it frustrating that the P-39 seems to crop up in every bluddy thread on this forum...and it's the same people having the same arguments on all the threads. Nobody's pre-existing perspectives are getting swayed by arguments in either direction. There's a lot of transmitting but not a lot of receiving going on.
> 
> Frankly, it's getting boring.


I hate the Brewster Buffalo.  I'll show myself out...

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## Simon Thomas (Jan 16, 2021)

nuuumannn said:


> Part of the problem with the Stirling was that construction of the prototype was begun before trials with the small scale aircraft had been completed, which meant Short didn't foresee that the wing's angle of incidence was too shallow, which meant it would have had an inordinately long take off run fully loaded, so its gangly undercarriage was lengthened to steepen the angle at which the wing began to produce adequate lift to get the thing off the ground.


I don't buy that. The Empire wing incidence was spot on, as the aerodynamics and hydrodynamics of the TO run of a flying boat is rather critical. Arthur Gouge had already designed a flying boat that was incapable of lift off from the water. After learning his lesson, he didn't suddenly forget how to angle airfoils when he worked on the Stirling.
The incidence problem was not identified by Parker when he was running the factory tests, rather it was a complaint from the pilots at RAE when the factory testing was well advanced.
If Shorts was able to "correct" the wing incidence wrt the airframe, the cruise angle of the airframe would have been sub-optimal.
Any pilot can lift off at the correct airspeed - having to add a few more degrees nose up is not that complicated or time-consuming. Having said that, the Cessna Cardinal is an interesting example of having to re-design an aeroplane due to pilots failing to follow the manual .


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## GrauGeist (Jan 16, 2021)

jmcalli2 - I'll (once again) post an actual Bell Aircraft image of the propulsion unit for a P-39Q.
In the image, is shown the Allison V-1710-85 (which was obviously mounted to the airframe), the 60" rear shaft, the carrier bearing/coupling (which was mounted to the airframe), the 60" foreward shaft and the gearbox/propeller mount (which was mounted to the airframe).
Now, there were only THREE points of contact for this assembly:
1. Engine
2. Carrier bearing
3. Gearbox.







That's it - nothing more. Period.

So calm the eff down.

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## Glider (Jan 16, 2021)

That shaft only weighed 10 pounds?


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## GregP (Jan 16, 2021)

The Allison V-1710 has exactly four points of attachment. There is no "crankcase extension, " and the driveshaft simply bolts to the extension shaft flange sticking out of the front of the gearbox. I have personally worked on some 15 of them and worked in a shop that has 150+ of them, a mixture of E's and F's and a few odd G's.

Here's a F-series engine:




Note it has a propeller shaft sticking out of the gearbox where the propeller mounts.

Here's a turbo compund E-series:




It has an extension shaft sticking out of the front (left side) that is very short compared with the F-series.

There is no magic here. You can make an E-engine by simply removing the nosecase from an F-engine and bolting on an E-engine front case. And there is no "stucture" supporting the driveshaft. The only point of connection to the engine is the extension shaft.

Honestly jmcalli2, if you're going to fuss at the entire forum, you at LEAST should go look at the airplane or engine you're fussing about.

War Emergency performance numbers are not very interesting because they very seldom ever got used. If they DID get used, the engine usually had to be pulled and changed, depending on group policy. Pilots were very unlikely to use WER when far from home because abusing your engine when you were several hundred miles from home was not every smart and not very good for survival. If you were going to have engine issues and bail out or were forced land, it didn't make sense to court disaster unless your life was in immediate danger.

The P-39N-1 performance test dated 17 Oct 42 used 50.5" MAP and the max rate of climb was 3,920 fpm at 11,000 ft. It dropped off pretty steeply from 11,000 ft. upward and was down to 2,630 fpm at 20,000 ft. 50.5" MAP was takeoff power and 52" MAP was approved just for takeoff and up to 5 minutes after takeoff. Military power was 44.2" MAP and it was approved for up to 15 minutes. Max continuous power was 39.2" MAP. 55" or 57" MAP wasn't even approved when the Pilot's Operating Handbook was written, and it was released in 1 Feb 1943.

The gross weight for the test from wwiiaircraftperformance was 7,274 lbs. . Normal load was 7,500 lbs. or more, so I guess the test was conducted without the center fuel tank ... which was generally needed in the Pacific since the range was nothing spectacular without it.

Wing tanks held 87 gallons and aux tank held 75 gallons. You needed a reserve of fuel, so if you had no aux tank, you'd generally plan for 70 gallons. If you were cruising at 2600 rpm, you had from 210 to 255 miles range. You COULD get up to 430 miles, but you'd be cruising at 2200 rpm and 215 mph or so at low MAP. Without the aux tank, you don't get many places in the Pacific, so they all generally hauled the aux tank. Gross weight was higher than 7,274 lbs. for Pacific operations unless you were doing CAP for the home airfield.

The rate of climb for the P-39N-0 and N-1 was 2,700 fpm and 44.5" MAP (15-minute limit for combat) at sea level, and it went down from there. Ferry climb was 1,350 fpm at sea level, again for 15 minutes. The performance charts note you increase the time to climb by a set percent for each 10°C above 0°C free air temperature. In the Pacific, there were damned few days when the temperature was 0°C, so NONE of the Pacific P-39N's likely climbed as well as 2,700 fpm right off the runway. That's an estimate, of course, but I never saw 0°C in the South Pacific any time I was ever there personally.

If you flog the engine and run it up to 57" MAP, you have a very short duration experience with good climb rates. The Soviets used them at 70" MAP and more, but they didn't fly in the USAAC/F where that would likely get you grounded if it happened very many times. The crew chief could tell because the wire across the throtte quadrant would be broken and it had to be reported.

Moral of the story is that yes, you CAN get 3,900 fpm climb rate from the P-39N in a test of WER climb for a short time, but the operating airplanes in-service in the Pacific and the ETO generally didn't get anywhere NEAR that performance when they were operated by the book at usual weights. Most were.

You two spouting about the P-39 won't change the FACT that the U.S.A. never embraced the airplane and it wasn't anywhere NEAR as good as a Spitfire V or an Fw 190A-5. It could have been the best fighter in the world (wasn't) and the U.S.A. would still not have embraced it due to the solidly mediocre performance of the first several thousand of them. After that, nobody wanted them. Oh yeah, it also had a solidly anemic combat record in U.S. service. The Soviets operated them in cold weather and ran the engines hard, and the P-39 seemed to thrive there, but not when and where the U.S.A. operated it.

In actual history, it ranks down near the bottom of the WWII fighters in U.S. use, right close to the Buffalo but definitely above the Buffalo. Much ado about nothing doesn't change that.

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## Jugman (Jan 16, 2021)

GrauGeist The shafts were only 48.5625" long. overall length of a single-stage E was 194" vs 85.625 for an F.

Glider total additional weight for an E was 90lbs. most of that was the drive shaft

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## buffnut453 (Jan 16, 2021)

P-39 Expert said:


> I hate the Brewster Buffalo.  I'll show myself out...



There's no accounting for taste...or even lack thereof. 

Truth be told, I'm really, REALLY struggling with the concept of anyone hating an inanimate object. It has to be the most futile of actions given that the object, being inanimate, has no conception of the feelings anyone may have about it.


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## pbehn (Jan 16, 2021)

GregP said:


> So, pretty much the entire Allied aviaiton world thought the Fw 190 was the best fighter in the world when it came out, even the Spitfire V guys, but you are saying the P-39N was a match for it?
> 
> .


This is my issue with the discussion the timing, the first P-39s to enter RAF service were not at all sorted and more of a danger to its own pilots than the enemy. These aircraft were contemporaries of the Fw-190. By the time 601 squadron packed these early versions off to Russia the Spitfire Mk IX and the Mustang Mk Is were starting to appear and the Fw 190 was a beast.

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## XBe02Drvr (Jan 16, 2021)

buffnut453 said:


> Truth be told, I'm really, REALLY struggling with the concept of anyone hating an inanimate object.


I used to think the P39 was a cool airplane. I'm a changed man now, and have learned to embrace my inner bigot. Thanks, Expert and JMCalli!

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## pbehn (Jan 16, 2021)

XBe02Drvr said:


> I used to think the P39 was a cool airplane. I'm a changed man now, and have learned to embrace my inner bigot. Thanks, Expert and JMCalli!


Maybe we could come together as a group and admit when we became haters, I wasn't aware at the time but I think it was when the 1971 Airfix catalogue was printed, I was still in my "box top art" phase.


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## nuuumannn (Jan 16, 2021)

Simon Thomas said:


> I don't buy that.



Whether you buy it or not doesn't mean it didn't happen.

Shorts Aircraft since 1900, C.H.Barnes (Putnam, 1989 revised edition):

"The Martlesham test pilots were impressed by its good handling qualities, but considered its take-off and landing runs rather too long in view of unavoidable future growth in the weight of the full-size Stirling; they recommended an increase of 3 degrees in wing incidence, which had purposely been kept to the optimum (31/2 degrees) for minimum cruising drag, but tooling up on the Stirling production line had already passed the point at which any such change could be made in the wing-fuselage junction design without altering the entire bomb suspension structure; quite apart from the cost of so radical a design change, the delay in delivery would have been totally unacceptable. So Gouge adopted the compromise solution of adding 3 degrees to the ground angle by lengthening the main landing gear."

It's in multiple entries on the Short S.31 half scale aircraft, even on wikipedia:

"There was one notable criticism amongst the feedback from pilots, being that the length of the take off run was considered to be excessive and that improvements would be desirable. Fixing this required that the angle of the wing to be increased for take off; however, if the wing itself was modified, the aircraft would fly with a nose-down attitude while cruising (as in the Armstrong Whitworth Whitley); making this change was also complicated by the fact that work on the production line had already reached an advanced stage. Thus, Shorts lengthened the undercarriage struts to tilt the nose up on take-off, leading to its spindly gear which in turn contributed to many take off and landing accidents."

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## jmcalli2 (Jan 16, 2021)

Glider said:


> That shaft only weighed 10 pounds?



I've never seen the drive shaft weight referenced.

It was however 10 feet long.

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## pbehn (Jan 16, 2021)

nuuumannn said:


> Whether you buy it or not doesn't mean it didn't happen.
> 
> Shorts Aircraft since 1900, C.H.Barnes (Putnam, 1989 revised edition):
> 
> "The Martlesham test pilots were impressed by its good handling qualities, but considered its take-off and landing runs rather too long in view of unavoidable future growth in the weight of the full-size Stirling; ."


 Were these comments valid or just not appreciating a new normal for take off runs? By all accounts I have read later Lancasters just laboured up in the air especially when carrying something like an Upkeep, Tallboy and Grandslam or even a normal load out for a very long mission

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## Shortround6 (Jan 16, 2021)

I could be wrong but the Stirling dated from the era of very short RAF airfields, even for bombers which lead to that whole catapult the Manchester scheme.

Flying boats were built because they had, in theory, nearly unlimited runway lengths in order to get up to take-off speed. 

The Poor Stirling may have been caught by timing and changing operational environments. 
Couldn't get out of the pea patch RAF airfields during early development and was replaced by aircraft that needed much larger airfields. Stirlings capabilities did increase with the larger airfields (higher gross weight) but it was too late to change the basic airframe. Getting both production lines bombed sure didn't help early deployment either so there was little opertunity for it to make a name for itself before the Halifax and Lancaster showed up. 

1st thousand bomber raid on Germany 30/31st of May 1942.

88 Stirling heavy bombers 
131 Halifax heavy bombers 
73 Lancaster heavy bombers 
46 Manchester medium bombers 

Plus all the other odds and sods. 
Had the Factories not been bombed (or hit?) dozens or scores more Stirlings may have been available at that point in time and the Stirling may have had at least a few weeks/months in the limelight and not been competing with aircraft that were around two years newer?

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## pbehn (Jan 16, 2021)

Shortround6 said:


> I could be wrong but the Stirling dated from the era of very short RAF airfields, even for bombers which lead to that whole catapult the Manchester scheme.
> 
> Flying boats were built because they had, in theory, nearly unlimited runway lengths in order to get up to take-off speed.
> 
> ...


Possibly the interaction of military and political decisions and comments. Saying the take off run is too short is the same as saying the runways must be made longer, but making lots of longer runways is a political decision. The local BC airfield to me started to be developed in 1938 and became operational in 1941. I think the Stirling and the Whitley were caught in this limbo and suffered because of it, by the time of the 1000 bomber raid in May 1942 there were many very long runways in UK and 60,000 people constructing more.


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## Glider (Jan 16, 2021)

jmcalli2 said:


> I've never seen the drive shaft weight referenced.
> 
> It was however 10 feet long.


P39 - can I ask for your views on this


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## nuuumannn (Jan 16, 2021)

pbehn said:


> Were these comments valid or just not appreciating a new normal for take off runs?



Well, it depends on several things. What, in 1938 - 1940 was considered a "too long" take-off or landing run? This gets into the territory of contemporary airfield design, which is a different topic altogether, but remember, the judgement was made whilst the S.31 was under trial by the Aircraft and Armament Experimental Establishment, which was designed to work as an evaluation of equipment and to make recommendations based on the status quo, not just a bunch of pilots voicing their opinions. Clearly changes were made to the Stirling's undercarriage as a result - take a look at a schematic and it is easy to see the added extension to the original layout.

No. 218 (Gold Coast) Squadron 1936-1945: Image (wordpress.com) 



Shortround6 said:


> The Poor Stirling may have been caught by timing and changing operational environments.
> Couldn't get out of the pea patch RAF airfields during early development and was replaced by aircraft that needed much larger airfields.



I think you might be right. The British underwent a massive airfield building programme in 1940/1941 and the standard "Type A (Bomber) Dispersed Airfield", with its lengthy concrete runways, dispersal pans and triangular layout became a familiar sight around the country. Mind you, everyone in aviation, not just the RAF was playing catch up during the late 30s in terms of the new technology and how aircraft design was changing everything.

This is RAF East Fortune in Scotland, completed in late 1941 and opened in 1942; typical of the new style of airfield being built in large numbers round the country at the time.





EF1942

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## GregP (Jan 16, 2021)

An Allison F3R (V-1710-39) came in at 1335 lbs. The E4R (V-1710-35: same power section and auxiliary section as F3R ... just a new nosecase) came in at 1425 lbs. I can tell you from personal experience that the remote gearbox used in the P-39 / P-63 is heavier than the nosecase on an F-series engine. A friend overhauled one for the CAF.

So, the driveshaft, center bearing support and everything associated with it weigh something like 50 - 60 lbs. It isn't heavy by any means. Max it could weigh might be 65 lbs. or so.

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## Simon Thomas (Jan 16, 2021)

nuuumannn said:


> Whether you buy it or not doesn't mean it didn't happen.


Sorry I should have been more specific. I was referring to your comment "Part of the problem with the Stirling was that construction of the prototype was begun before trials with the small scale aircraft had been completed, which meant *Short didn't foresee that the wing's angle of incidence was too shallow* ".

You are accusing Shorts / Gouge of getting the angle of incidence wrong. That is what I don't agree with. As I said, Gouge knew what he was doing. If Gouge was able to change the wing incidence like RAE wanted, it would have flown at a crazy nose down angle like the Whitley with the corresponding increase in drag.

The compromise solution was a reasonable outcome to an unnecessary request. Maybe making the retract mechanism stronger would have helped with the many failures - although again the weight would have increased.


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## DerAdlerIstGelandet (Jan 16, 2021)

jmcalli2 said:


> That bearing just sort of floats on air...
> 
> You morons have a problem.
> 
> ...



You morons?

Who are you calling a moron?

Knock it off with the insults.


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## Admiral Beez (Jan 16, 2021)

pinsog said:


> When you guys are suggesting how fantastic a Seafire would have been, consider how it compared to a 6 gun Wildcat:
> 
> View attachment 541022
> View attachment 541023


It may or may not better than the Wildcat, but I’d like to see the first Seafire enter service in 1941 from the onset with folding wings, modified (strength and oleo) undercarriage and greater internal fuel.


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## DerAdlerIstGelandet (Jan 16, 2021)

tyrodtom said:


> I about got caught by a stall on final in a Piper Cherokee.
> Cross wind , turned from base to final a little late, tightened the turn too much to try and line up with the runway.
> Horn went off, aircraft shook a little, and I eased out of the bank, put the nose down a little, then lined up late on final.
> I almost landed short. A experienced pilot who observed my landing was pretty critical of my performance.
> ...



I had that happen to me in Cherokee on one of my cross country solos during my flight training. Total pucker factor.


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## DerAdlerIstGelandet (Jan 16, 2021)

I have been really busy, and am now just getting caught up on this thread. This thread is so exhausting and tiresome. But one thing is for sure...

I am getting really tired of this bickering and insults. If I see one more person call someone else a moron, or some other insult that member will be sent on a vacation to cool off.

A heated debate is fine, but conduct it like an adult, or don’t do it all. Kapeesh?

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## Marcel (Jan 17, 2021)

P39 seems to pop up everywhere on this forum, starting streetfights amongst the members. Must be the groundhogs. They are everywhere. Nasty little buggers.

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## PAT303 (Jan 17, 2021)

jmcalli2 said:


> And I feel sorry for you.



The Spitfire evolved throughout the war because the airframe had development growth, so did the Me109, FW190, P47 and especially the P51, the P39 had zero growth potential because the planes design was fundamentally flawed, you can sugar coat it as much as you want but everyone involved with running the air war new it, why waste time and effort on it when better designs were already in service?.


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## Shortround6 (Jan 17, 2021)

Larry Bell and boys sure screwed up when they went to all the trouble to design and build the P-63 when all they had to do was tweak the P-39 (take the armor out of the nose and move the radio),

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## DerAdlerIstGelandet (Jan 17, 2021)

Marcel said:


> P39 seems to pop up everywhere on this forum, starting streetfights amongst the members. Must be the groundhogs. They are everywhere. Nasty little buggers.



Let’s change the forum’s name from WW2Aircraft.net to P39 Hijacks The Forum.net

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## GrauGeist (Jan 17, 2021)

Oddly enough, in the P-39N pilot's manual (dated February 1943), they seemed to be under the impression that the front armor was needed...

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## Reluctant Poster (Jan 17, 2021)

Shortround6 said:


> I could be wrong but the Stirling dated from the era of very short RAF airfields, even for bombers which lead to that whole catapult the Manchester scheme.
> 
> Flying boats were built because they had, in theory, nearly unlimited runway lengths in order to get up to take-off speed.
> 
> ...


The problem with the Stirling was its enormous fuselage. An empty Stirling weighted 4,000 lb more than an empty Lancaster.

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## Glider (Jan 17, 2021)

Reluctant Poster said:


> The problem with the Stirling was its enormous fuselage. An empty Stirling weighted 4,000 lb more than an empty Lancaster.


I think the Sterling was designed when the RAF didn't know quite what it wanted. IIRC one of the design parameters was that it could be broken into three and carried by rail, quite why you would want to do that is a total mystery to me.
It did make it quite a good freighter and troop transport


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## Glider (Jan 17, 2021)

GrauGeist said:


> Oddly enough, in the P-39N pilot's manual (dated February 1943), they seemed to be under the impression that the front armor was needed...
> 
> View attachment 609288



It's such a damned nuisance, those gunners on the bombers your attacking, firing back when your trying to shoot them down.

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## pbehn (Jan 17, 2021)

Glider said:


> I think the Sterling was designed when the RAF didn't know quite what it wanted. IIRC one of the design parameters was that it could be broken into three and carried by rail, quite why you would want to do that is a total mystery to me.
> It did make it quite a good freighter and troop transport


I think it was a half baked idea of sending Stirlings by ship and rail to outposts of empire to bomb things, carry supplies and act as a transport.


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## nuuumannn (Jan 17, 2021)

Simon Thomas said:


> You are accusing Shorts / Gouge of getting the angle of incidence wrong. That is what I don't agree with.



Easy, tiger - let's not get personal. I think you might be reading too much into my wording as I'm not accusing anyone of anything. Obviously there was some miscalculation in its design as the aircraft did not meet a few of the criteria in B.12/36, notably and obviously altitude performance. This was common, as all three of Britain's first generation heavies suffered from design issues that took a bit of effort to fix. The Halifax suffered severe rudder overbalance and was notoriously draggy and couldn't meet the performance criteria, the Manchester suffered from aerodynamic issues, aside from the unreliable engines, which thankfully were cured by the time the Lancaster was put into production.


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## pbehn (Jan 17, 2021)

Make a gunsight that can be taken out of the way for a forced landing, how many pilots were put out of action for a long time by hitting their heads on them?


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## Shortround6 (Jan 17, 2021)

Shorts/Gouge were experimenting with the Gouge flap. 
Gouge flap - Wikipedia

Perhaps they thought they had the take-off and landing covered until the plane gained about 9,000lbs due to air ministry add ons. ??


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## jmcalli2 (Jan 17, 2021)

Glider said:


> P39 - can I ask for your views on this




You don't believe the drive shaft was 10 feet long?

LiTOT: P-39: Why a Rear Engine Installation


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## jmcalli2 (Jan 17, 2021)

DerAdlerIstGelandet said:


> You morons?
> 
> Who are you calling a moron?
> 
> Knock it off with the insults.



It took a LOT to get me to call them morons.

They earned it.

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## jmcalli2 (Jan 17, 2021)

PAT303 said:


> The Spitfire evolved throughout the war because the airframe had development growth, so did the Me109, FW190, P47 and especially the P51, the P39 had zero growth potential because the planes design was fundamentally flawed, you can sugar coat it as much as you want but everyone involved with running the air war new it, why waste time and effort on it when better designs were already in service?.



I never said the P-39 was a world beater.

Sorry you think your post is an insult to me, as is obvious by your tone.

The P-39 was better than the P-40, as evidenced by the follow on, the P-63 which was as much like the P-39 as the P-51H was like the P-51A; the P-40 ended production in 1944 with nothing to follow on.

The P-39 was good enough. So was the P-40. Just like the M4 Sherman.

You all have some fetish against the plane.

You attack anyone who says anything good about it, to the point of making things like 'whipping drive shafts' up.

I think that's sad.


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## jmcalli2 (Jan 17, 2021)

Shortround6 said:


> Larry Bell and boys sure screwed up when they went to all the trouble to design and build the P-63 when all they had to do was tweak the P-39 (take the armor out of the nose and move the radio),



The P-63 was the result of tweeting the P-39.


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## jmcalli2 (Jan 17, 2021)

buffnut453 said:


> My-oh-my, we're getting passionate about this topic! I'm pretty sure nobody on this forum "hates" any aircraft. We are all interested in learning more about aviation and to explore the reasons why things happened.
> 
> Personally, I find it frustrating that the P-39 seems to crop up in every bluddy thread on this forum...and it's the same people having the same arguments on all the threads. Nobody's pre-existing perspectives are getting swayed by arguments in either direction. There's a lot of transmitting but not a lot of receiving going on.
> 
> Frankly, it's getting boring.



Took a lot of words to say that.

If you were really bored, you'd have skipped to a different topic.

Nice bit of passive-aggression though.


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## tyrodtom (Jan 17, 2021)

jmcalli2 said:


> I never said the P-39 was a world beater.
> 
> Sorry you think your post is an insult to me, as is obvious by your tone.
> 
> ...



I think you're calling me a liar.
Nobody attacked you, or got personal, you're the one that crossed that threshold. 
I've, along with other people on this forum, have seen the damage a whipping drive shaft can do.
Any driveshaft has that potential, the P-39 was no exception.
There's thousands of lost WW2 aircraft that nobody knows what happened to them, or their pilots. 
WW2 aircraft crash sites are still being found to this day and excavated, usually to recover remains.


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## Shortround6 (Jan 17, 2021)

jmcalli2 said:


> The P-63 was the result of tweeting the P-39.



Yep, they tweaked a whole new wing, tweaked the wings location on the fuselage, tweaked about 2 feet of extra fuselage length, tweaked the wheelbase and tread.
In fact just about everything on the P-63 was bigger ( Larger horizontal stabilizer area, larger vertical stabilizer area, larger propeller, etc etc etc) 
It just sort of looks like the P-39. 
BTW the Army ordered two XP-63 prototypes in June of 1941.


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## DerAdlerIstGelandet (Jan 17, 2021)

Time for some cooling off.

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## XBe02Drvr (Jan 17, 2021)

pbehn said:


> Make a gunsight that can be taken out of the way for a forced landing, how many pilots were put out of action for a long time by hitting their heads on them?


Inertia reel shoulder straps. They existed, but there seemed to be shortage of intracranial light bulbs in the aviation world. "Duhh! Why didn't I think of that!"


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## GrauGeist (Jan 17, 2021)

Shortround6 said:


> Yep, they tweaked a whole new wing, tweaked the wings location on the fuselage, tweaked about 2 feet of extra fuselage length, tweaked the wheelbase and tread.
> In fact just about everything on the P-63 was bigger ( Larger horizontal stabilizer area, larger vertical stabilizer area, larger propeller, etc etc etc)
> It just sort of looks like the P-39.
> BTW the Army ordered two XP-63 prototypes in June of 1941.



And it still had armor up front!

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## buffnut453 (Jan 18, 2021)

jmcalli2 said:


> Took a lot of words to say that.
> 
> If you were really bored, you'd have skipped to a different topic.
> 
> Nice bit of passive-aggression though.



It's hard to skip the thread given that there's nothing in the title to suggest it contained the same P-39 arguments that have discussed ad nauseam in at least 2 other different threads. I actually have an interest in the topic of discussing designs that could have been improved, I just don't want to see the same arguments here that already have existing type-specific threads. 

Pretty rich to be accusing me of passive aggression when you proclaim anyone who criticizes the P-39 as being a "hater", not to mention your active aggression of calling other forum members "morons".


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## Marcel (Jan 18, 2021)

buffnut453 said:


> It's hard to skip the thread given that there's nothing in the title to suggest it contained the same P-39 arguments that have discussed ad nauseam in at least 2 other different threads. I actually have an interest in the topic of discussing designs that could have been improved, I just don't want to see the same arguments here that already have existing type-specific threads.
> 
> Pretty rich to be accusing me of passive aggression when you proclaim anyone who criticizes the P-39 as being a "hater", not to mention your active aggression of calling other forum members "morons".


Guys (in general), Adler dealt with the situation. I suggest all of you leave it behind. I’ll close this thread if I see it happen again before any more have to be put in the “cooler”.

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## MikeMeech (Jan 18, 2021)

pbehn said:


> I think it was a half baked idea of sending Stirlings by ship and rail to outposts of empire to bomb things, carry supplies and act as a transport.





Glider said:


> I think the Sterling was designed when the RAF didn't know quite what it wanted. IIRC one of the design parameters was that it could be broken into three and carried by rail, quite why you would want to do that is a total mystery to me.
> It did make it quite a good freighter and troop transport



Hi

It is hardly a 'secret' or 'unknown' why large aircraft were designed to be able to split into smaller sections, in production these aircraft were manufactured in sections and fitted out before being joined together in the factories. This meant that if an aircraft was damaged by enemy action or in an accident that was repairable it could be divided up into these sections and sent by road or rail to a repair facility, each section could be repaired individually and fitted together again or various sections reused on different airframes as appropriate. 
Below are Lancaster forward sections under repair:





A Lancaster split up into 'Queen Mary' trailer loads:




A Halifax split into 'Queen Mary' loads:




Why do you think this idea was 'half-baked' or a 'mystery' for the Stirling, when it appears to be a very sensible and practical idea for all large aircraft in the circumstances of the period?

Mike

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## DerAdlerIstGelandet (Jan 18, 2021)

Marcel said:


> Guys (in general), Adler dealt with the situation. I suggest all of you leave it behind. I’ll close this thread if I see it happen again before any more have to be put in the “cooler”.



Thank you.


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## Koopernic (Jan 18, 2021)

Glider said:


> I think the Sterling was designed when the RAF didn't know quite what it wanted. IIRC one of the design parameters was that it could be broken into three and carried by rail, quite why you would want to do that is a total mystery to me.
> It did make it quite a good freighter and troop transport


The Whitley could carry 10 paratroopers. I think this was not uncommon. I suspect that even the Manchester spec allowed for some transport capability


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## Glider (Jan 18, 2021)

MikeMeech said:


> Hi
> 
> It is hardly a 'secret' or 'unknown' why large aircraft were designed to be able to split into smaller sections, in production these aircraft were manufactured in sections and fitted out before being joined together in the factories. This meant that if an aircraft was damaged by enemy action or in an accident that was repairable it could be divided up into these sections and sent by road or rail to a repair facility, each section could be repaired individually and fitted together again or various sections reused on different airframes as appropriate.
> Below are Lancaster forward sections under repair:
> ...


Very good and interesting photographs. Almost any aircraft can be broken down into components as no aircraft (that I am aware of) is built in one piece. The difference is the reason for breaking it down. The Sterling is the only one I am aware of that was designed to be broken down so it can be shipped by rail. Being an aircraft of some size and range it can of course fly, wherever it can go by train.


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## Glider (Jan 18, 2021)

Koopernic said:


> The Whitley could carry 10 paratroopers. I think this was not uncommon. I suspect that even the Manchester spec allowed for some transport capability


When I made my observation I was thinking of an operation where originally the Sterling's were going to assist some USAAF Liberators with the transport of troops and equipment behind German lines. When they arrived and it was realised that using the Sterling instead of the Liberator would mean reducing the number of aircraft by half, the lift was solely undertaken by the Sterling's.

I forgot to add that from the start the Sterling was designed to carry 25 troops and equipment. It's high 'stance' also made some things easier as it was relatively easy to carry large items such as 6pd AT guns and Jeeps under the fuselage though how often this was done is open to conjecture.

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## Glider (Jan 18, 2021)

jmcalli2 said:


> You don't believe the drive shaft was 10 feet long?
> 
> LiTOT: P-39: Why a Rear Engine Installation


I don't doubt that it was 10ft long. It was claim that the shaft only weighed 10 pounds I wasn't expecting. It's certainly possible but quite an achievement considering the load the shaft would be under.


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## swampyankee (Jan 18, 2021)

The P-39 was very much a niche design. Unfortunately, the niche it fit wasn't with any of the western Allies; while the USSR used it effectively Soviet secrecy and western PC minimized its contributions.

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## tyrodtom (Jan 18, 2021)

XBe02Drvr said:


> Inertia reel shoulder straps. They existed, but there seemed to be shortage of intracranial light bulbs in the aviation world. "Duhh! Why didn't I think of that!"


 Did they have inertial shoulder straps in WW2 era aircraft ?

The pictures I've seen looks very similar to the seat belts NASCAR still uses, except modern are nylon fabric instead of the canvas of WW2 belts.
NASCAR still doesn't allow any inertial take up on seatbelts. They expect you to tighten them, tight.
But in crashes even 3 inch belts stretch, and the body deforms, you move a lot more than you'd expect in a hard crash.

I know because I hit the padded header bar of the roll cage, with a helmet on, hard enough to get a mild concussion, and I though my belts were tight.

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## XBe02Drvr (Jan 18, 2021)

tyrodtom said:


> Did they have inertial shoulder straps in WW2 era aircraft ?


AFAIK, no they didn't. I understand they were in use in some tanks and PT boats, but like many innovations, encountered some resistance from sceptics. I've flown gliders and an acro bird or two that had the old WWII style canvas belts. Not great, as you say, but better than nothing. It's really hard to check six with unyielding shoulder straps, which perhaps explains those WWII gunsight head knocks. In the back seat of an A4 or F4 it's much easier to keep track of traffic in a furball with inertia reel harnesses.


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## MikeMeech (Jan 18, 2021)

Glider said:


> Very good and interesting photographs. Almost any aircraft can be broken down into components as no aircraft (that I am aware of) is built in one piece. The difference is the reason for breaking it down. The Sterling is the only one I am aware of that was designed to be broken down so it can be shipped by rail. Being an aircraft of some size and range it can of course fly, wherever it can go by train.



Hi

According to Barnes in 'Shorts Aircraft since 1900' page 371, the requirements for specification B.12/36, which the Stirling was one of the designs, included the following:

"Other requirements included the breakdown of the airframe, by means of bolted or screwed joints, into components no larger than the existing Air Ministry packing-case sizes, which in turn were based on the capacity of standard-gauge railway wagons, and all such components had to be strictly interchangeable."

This also applied to the P.13/36 designs as well (Manchester and Halifax). These are requirements for aircraft or parts of aircraft which could not fly, it is not 'instead' of flying as you appear to imply. Supply depots and many airfields were either near or had railway links alongside so it did make sense in many cases.

Mike


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## tyrodtom (Jan 18, 2021)

XBe02Drvr said:


> AFAIK, no they didn't. I understand they were in use in some tanks and PT boats, but like many innovations, encountered some resistance from sceptics. I've flown gliders and an acro bird or two that had the old WWII style canvas belts. Not great, as you say, but better than nothing. It's really hard to check six with unyielding shoulder straps, which perhaps explains those WWII gunsight head knocks. In the back seat of an A4 or F4 it's much easier to keep track of traffic in a furball with inertia reel harnesses.



I'm sure they would have kept the shoulder straps loose during flight.
In a lot of cases you probably don't know you're going to have a crash landing until everything suddenly goes all to hell, and you've got your hands too busy to take a couple of seconds to tighten your belts.

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## pbehn (Jan 18, 2021)

tyrodtom said:


> I'm sure they would have kept the shoulder straps loose during flight.
> In a lot of cases you probably don't know you're going to have a crash landing until everything suddenly goes all to hell, and you've got your hands too busy to take a couple of seconds to tighten your belts.


If you look at any Spitfire or Hurricane pilot sat in the cockpit, it is impossible to tighten the straps enough to stop your head hitting it in a hard landing, some pilots like Bob Doe almost lost their face and were out for months if not permanently. meninroad: “© IWM (HU 54419) Portrait of a sergeant pilot of No. 610 Squadron, sitting in the cockpit of a Spitfire, … | Battle of britain, Fighter pilot, Luftwaffe


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## GregP (Jan 18, 2021)

There were great fighters in WWII, but they weren't designed with pilot safety in the event of a forced landing as a factor of consideration.


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## GrauGeist (Jan 18, 2021)

At least they tried to lessen the impact with pads, like on the German Revi and the US N-9 sights...


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## SaparotRob (Jan 18, 2021)

swampyankee said:


> The P-39 was very much a niche design. Unfortunately, the niche it fit wasn't with any of the western Allies; while the USSR used it effectively Soviet secrecy and western PC minimized its contributions.


I wonder if the P-39 had been a strictly Soviet product (through licensing or whatever) it would have had a much different reputation.

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## pbehn (Jan 18, 2021)

SaparotRob said:


> I wonder if the P-39 had been a strictly Soviet product (through licensing or whatever) it would have had a much different reputation.


It was fighting a different war on a different front. After D-Day the war in the west was similar (apart from bombing raids on Germany itself) performance at altitude and range don't matter so much but numbers do and with the Russians the P-39 was part of a huge force with planes to fit any and every niche.

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## gruad (Jan 18, 2021)

Ok, this is a bit speculative, but would the Fw190/BMW spinner option helped with the B29/R3350 combination.

Many B29s were lost to engine fires and IIRC correctly the engine required a huge amount of maintenance where the rear bottom cylinders had to be regularly replaced. 

Also I heard that the cowling design was a problem as when it was open to allow cooling air, it was very draggy and could become stuck dropping the bomber out of formation and increasing fuel consumption.


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## wuzak (Jan 18, 2021)

gruad said:


> Ok, this is a bit speculative, but would the Fw190/BMW spinner option helped with the B29/R3350 combination.
> 
> Many B29s were lost to engine fires and IIRC correctly the engine required a huge amount of maintenance where the rear bottom cylinders had to be regularly replaced.
> 
> Also I heard that the cowling design was a problem as when it was open to allow cooling air, it was very draggy and could become stuck dropping the bomber out of formation and increasing fuel consumption.




The ducted fan and cooling exits without gills would have helped.


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## GregP (Jan 18, 2021)

The Planes of Fame flies a Flugwerk Fw 190 repolica with an R-2800 in it and a cut down prop from a C-47 Glider Tug wide-chord unit. There are small oil coolers all over the inside of the cowling, similar to the German approach. Not surprisingly, it got hot on its first flight. The solution was to add two oil coolers, one under each wing, with very small inlets that do not detract from the looks or aerodynamics. 

Today, it flies without cooling problems and John Maloney hearded it around Reno in the Bronze Race in 2010 at 283 mph. The bronze winner was a Yak-3 at 317 mph, so it wasn't exactly slow but also wasn't exactly run very hard either since it was just a fun fly arond the pylons.

No real point here except that cooling was and IS an issue with the Fw 190 and all radials. Some handle it better than others. Basically, running an air-cooled radial at WEP means running it at high power until the oil gets to the upper limit of temperature. Then you either reduce power or have a forced landing when the radial throws a scrap iron fit up front and drips all over the windscreen.

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## XBe02Drvr (Jan 18, 2021)

gruad said:


> Many B29s were lost to engine fires


Once that magnesium accessory case caught fire, there was no putting it out. Next comes the header tank, then the wing spar. Time to git outta Dodge while the gittin's good!


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## XBe02Drvr (Jan 18, 2021)

GregP said:


> when the radial throws a scrap iron fit up front and drips all over the windscreen.


Such a way with words, Greg!


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## TheMadPenguin (Jan 19, 2021)

B-29: Give it a new wing (ok, 2 new wings) mounting 3 R2800s (as found in the P-47 with super and turbo) each instead of 2 3350s
The R3350 improved over time, so did the R2800 in the P-47.


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## Koopernic (Jan 19, 2021)

GregP said:


> The Planes of Fame flies a Flugwerk Fw 190 repolica with an R-2800 in it and a cut down prop from a C-47 Glider Tug wide-chord unit. There are small oil coolers all over the inside of the cowling, similar to the German approach. Not surprisingly, it got hot on its first flight. The solution was to add two oil coolers, one under each wing, with very small inlets that do not detract from the looks or aerodynamics.
> 
> Today, it flies without cooling problems and John Maloney hearded it around Reno in the Bronze Race in 2010 at 283 mph. The bronze winner was a Yak-3 at 317 mph, so it wasn't exactly slow but also wasn't exactly run very hard either since it was just a fun fly arond the pylons.
> 
> No real point here except that cooling was and IS an issue with the Fw 190 and all radials. Some handle it better than others. Basically, running an air-cooled radial at WEP means running it at high power until the oil gets to the upper limit of temperature. Then you either reduce power or have a forced landing when the radial throws a scrap iron fit up front and drips all over the windscreen.



Did anyone ever try an engine driven cooling fan on the R-2800?


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## MiTasol (Jan 19, 2021)

tyrodtom said:


> Did they have inertial shoulder straps in WW2 era aircraft ?



Yes and no
They had retractable shoulder harness but not inertia reels. The pilot had to lean back, wait about a second for the spring mechanism to pull the harness tight and then manually lock it in that position.

P-40 seat -- the circular item is the belt tensioner - the shaft across the front connects to the locked/free handle. The tension cable runs through the conduit to part way up the back of the seat then connects to the shoulder straps. On the P-40 there are also side adjusters for the lap straps that are quick adjust.

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## wuzak (Jan 19, 2021)

Koopernic said:


> Did anyone ever try an engine driven cooling fan on the R-2800?



There was one on the XP-56

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## P-39 Expert (Jan 19, 2021)

Glider said:


> P39 - can I ask for your views on this


The driveshaft weighed 10lbs according to Larry Bell in an interview once. I'll try and look it up when I get home. The center bearing that connected the two 5ft shafts was indeed securely mounted on the base of the very robust "canoe" that held the engine, pilot, nose armament, nose landing gear and remote reduction gear which drove the propeller. The "canoe" assembly was mounted on the wing which gave the whole thing a very sturdy construction.


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## P-39 Expert (Jan 19, 2021)

Shortround6 said:


> Larry Bell and boys sure screwed up when they went to all the trouble to design and build the P-63 when all they had to do was tweak the P-39 (take the armor out of the nose and move the radio),


What I'm saying is Bell/AAF should have put the -93 two stage Allison into the P-39 while they were waiting for the first P-63 to get finished. The -93 was in production in April 1943 but the first P-63 wasn't available until October. Seven wasted months, but then again I think the AAF was intentionally delaying the whole thing because it was just going to the Russians anyway.


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## TheMadPenguin (Jan 19, 2021)

P-39 Expert said:


> The driveshaft weighed 10lbs according to Larry Bell


I'm inclined to think this might be the truth in a strange (to us today) way. Armor plate (STS for example) was referenced in pounds, to tell the thickness, but that was pounds per square foot.
The drive shaft given as 10 pounds per linear foot makes good sense to me: two 50 pound sections making a 100 pound, 10 foot shaft.

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## swampyankee (Jan 19, 2021)

Koopernic said:


> Did anyone ever try an engine driven cooling fan on the R-2800?



All the helicopter installations used cooling fans. A well-designed airplane installation won’t need one.


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## GregP (Jan 19, 2021)

Hi XBe02Drvr,

Wish I could claim that wording, but it's a phrase Joe Yancey uses when an engine commits suicide. That's when he gets to repair them.

One Allison user had a unit run out of fuel (another person trying to fly with air in the gas tanks), and when they "pickled" the engine for transport for repair after the "ground strike," they removed all the spark plugs, put paper towels in the coolant openings, but left the spark plug holes open to the elements! So, when Joe got it, I was working there at the time, there was sand all in the cylinders, but the cooling jacket was pristine! Go figure! After complete disassembly, it needed to have all 12 cylinders honed. Other than that, it was good to go. Whoever took charge of the cleanup and aircraft retrieval wasn't exactly having his sharpest day that day.

Most of the scrap iron fits I have seen with Allisons were caused by the hand on the throttle / mixture levers. I have only seen two where the Allison failed.

In one, a distributor shaft broke cleanly. Luckily, the pilot was making a fast low pass down the runway at the time, traded airspeed for altitude, and landed without incident. The repair was simple and quick ... a new shaft and he was good to go. But, Joe didn't know that until the engine got to the shop and was examined, so it still had to be pulled and transported. I don't work there anymore, but we are still good friends.

The other one was a cylinder liner failure on Galcier Girl's attempt to recreate Operation Bolero. That was preventable in hindsight.

I'm not too sure how familiar with Allisons most in here are, but the pistons have four ring slots. Three up high (a compression ring and two oil rings), and one at the bottom of the piston skirt (an oil ring). The bottom ring prevents the piston from slapping in the bore when it is running. After WWII, they started using Allisons and Merlins for hydroplane racing, and those boys were nothing if not lazy when it came to going by the book for overhauls. One of their "tricks" was to chuck the pistons up in a lathe and remove the bottom ring groove. If they did that, they could remove and install the cylinder banks without cracking the engine cases. But, that leaves the piston no bottom support and it can slap back and forth in the bore. It will do that for about 100 - 250 hours and then crack the liner, which leaks coolant into the cylinder. The pilot can see the failure because coolant leaves a smoke trail. Some of the guys even drilled lightening holes in the piston skirt. I have a pair of those (only 3 rings and skirt holes) that used to be in Guy Lombardo's championship-winning hydroplane.

As it happens, the engines in Glacier Girl at the time had pistons with the bottom ring removed. That is no longer the case, and she is running very well these days. I hope she does so for a long time to come.

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## XBe02Drvr (Jan 19, 2021)

GregP said:


> The bottom ring repvents the piston from slapping in the bore when it is running.


Is that why Allisons could handle high MP, ultralow RPM cruise more gracefully than some of their contemporaries?


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## GregP (Jan 19, 2021)

Generally, Allison components are beefier and less numerous than Merlin components, including bolts. Merlins have about 13,000 parts in them, give or take a few. Allisons have about 7,000 parts in basically the same size package. Beefier parts generally mean less breakage at normal stress levels. Actually, they'd have the same dispalcement except the Allison has 0.1 inches more bore. Both have 6-inch stroke. The Merlin has a 5.4-inch bore while the Allison has a 5.5-inch bore. 1649 cubic inches versus 1710 all due to 0.1" of bore.

Not too sure if bottom piston rings are a real reason; Merlin pistons also have four rings with one at the bottom of the skirt. But, Allison rods will handle a LOT more power than Merlin rods. Merlin rods will give up and fail somewhere around 2500 hp. Allison rods will take more and the G-series rods will take over 4000 hp, so they use them in the racing "Merlins" at Reno that really have very little "Merlin" left in them. Yes, they have Merlin cases and crankshafts, but they generally run Allison G-series rods, aftermarket pistons and wrist pins, aftermarket valves and fuel systems, and a host of other mods. 

Basically, Racing Merlins are a "power system" composed of a lot parts that start with a Merlin engine case and cylinder bank set. Also, Allison bearings were the best at the time. The War Department made Allison share their bearing technlogy with Rolls Royce during the war. Otherwise, the TBO of the Merlin would never have been as good as it was. 

It would not have changed the way the Merlin ran; it ran great. But it DID change the time between overhaul, which helped during the war. Methinks the crew chiefs were busy anyway during the war. They'd have been even MORE busy had not Rolls Royce implemented the 0.020"silver over 0.040" lead over steel bearings that Allison shared.

As far ultra low rpm cruising, low rpm is more stressful to the rods and bearings than high rpm, assuming the "high rpm" is within book limits (basically 3,000 rpm). Once you get to 3,600 rpm, then the high rpm is more stressful to the engine as a whole. Nobody much thinks about it, but the bearings take a beating at and around idle since ignition basically pushes the pistons and rods down against the bearing surface while the engine is turning over very slowly. Both Allisons and Merlin bearings (and all inlines) are less stressed at 1800 rpm than they are at 900 rpm. Let's recall that one Allison cylinder, assuming WER of 1,600 hp, can produce 125 hp. That's a pretty big hit on the bearing.

Anyway, Allisons and Merlins were both good engines. If you were going to 25,000 feet and didn't have a turbocharger, then the 2-stage Merlin was the way to go. The Merlin was one of the great engines of the war, for sure, regardless of any other stories or intrigue behind the engine. It worked when it needed to work and went as high as was needed easily. The Allison could, too, but not without the high-altitude boost system affored by the turbocharger setup. I'd like to have seen a complete Merlin 2-stage supercharger adapted to an Allison power section. Maybe somebody did one but, if so, I have not seen it or heard of it.

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## wuzak (Jan 19, 2021)

P-39 Expert said:


> The "canoe" assembly was mounted on the wing which gave the whole thing a very sturdy construction.



What a radical concept. The wing connects to the fuselage!


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## MiTasol (Jan 19, 2021)

TheMadPenguin said:


> I'm inclined to think this might be the truth in a strange (to us today) way. Armor plate (STS for example) was referenced in pounds, to tell the thickness, but that was pounds per square foot.
> The drive shaft given as 10 pounds per linear foot makes good sense to me: two 50 pound sections making a 100 pound, 10 foot shaft.



Having hoisted P-39 drive shafts hundreds of time I can absolutely gaurantee they did no weigh 50lb though I do think they were weighed more than 10. If I get interested enough I will dig out my microfilm and see what the blueprint says.


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## GregP (Jan 19, 2021)

Hi MiTasol,

My estimate was the heaviest I think it could be based on POH weights, not a guess at actual weight. Think-wall shafts aren't very heavy in general.

I've seen one many times, but always inside the P-39/P-63, never all by itself. I'd guess most people who have seen one have not seen it by itself. They aren't exactly around in large numbers. Out of curiosity, how is it you have hoisted one so many times? Are you working on a P-39 restoration? If so, where? Again, just curious.


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## Reluctant Poster (Jan 19, 2021)

Glider said:


> I think the Sterling was designed when the RAF didn't know quite what it wanted. IIRC one of the design parameters was that it could be broken into three and carried by rail, quite why you would want to do that is a total mystery to me.
> It did make it quite a good freighter and troop transport


The Lancaster and Halifax were built to the same constraints. Their fuselages were divided into 4 sections.
This was not an unreasonable requirement. It allowed shipping overseas with assembly locally. Packing cases are shown in the following link
Harry Boyle's Tango over Takoradi > Vintage Wings of Canada

It also allowed dispersed construction. An excellent example of dispersed construction was the London Aircraft Production Group
https://www.rchs.org.uk/wp-content/uploads/2017/01/342-London-Aircraft-Production-Group.pdf

The Americans also adopted the idea of dividing the fuselage
_“Douglas found it necessary to break the DC-3 down to meet wartime schedules for the military version, the C-47. The fuselage was broken into three, later four, longitudinal sections, each of which could be assembled separately, and then installations were made in each section on a production line basis.”_

Finally, it should also be noted that the Supermarine 317 was designed to the same specification as the Stirling. The designs could not be more contrasting in terms of their bulk.
The overlay of the three bombers in the wiki article on the Stirling is eye opening
Short Stirling - Wikipedia
There was no reason for the Stirling to be 18 feet longer than a Lancaster.
I would hate to see how bulky Short would have made the Stirling without size constraints.

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## nuuumannn (Jan 19, 2021)

Reluctant Poster said:


> There was no reason for the Stirling to be 18 feet longer than a Lancaster.
> I would hate to see how bulky Short would have made the Stirling without size constraints.



The Stirling (and Halifax) have always appeared to me to be over-engineered the more I learn about them and a lot of that, particularly in the Stirling's case comes from Air Ministry interference and attempting to work within the specifics of the written requirements and specs. Short Brothers had experience with large multi engined aircraft (as did Handley page for that matter), yet the Stirling, a massive undertaking at the time fell short of the performance criteria of B.12/36 for numerous reasons and came with built-in obsolescence that could not be worked around without major redesign.

What it does illustrate (along with the Halifax) is that it wasn't easy to put into production large four-engined aircraft built to mid 30s specifications and anticipating whether or not they would be viable going forward. That the Manchester was Avro's very first attempt at a big (ish) all-metal aircraft is impressive (Avro had built Blenheims under licence as their first all-metal type in its workshops) and resulted in a noble but flawed effort, but essentially once the aerodynamic (and equipment) issues were worked out was a very sound design free of the performance constraints of the Stirling and the aerodynamic and overly complicated problems the Halifax suffered. Of course, the Manchester benefitted from the torpedo requirement in P.13/36, giving it that impressively large unobstructed bomb bay, as well as its inherent strength as a result of the catapulting requirement.

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## swampyankee (Jan 19, 2021)

SaparotRob said:


> I wonder if the P-39 had been a strictly Soviet product (through licensing or whatever) it would have had a much different reputation.



Sure. Nobody except _cognescenti_ would have heard of it.

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## nuuumannn (Jan 19, 2021)

swampyankee said:


> Nobody except _cognescenti_ would have heard of it.



Well, on this forum we're making damn sure that _everybody's_ heard of the P-39...

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## GregP (Jan 19, 2021)

Nothing really wrong with the P-39, but I think we've had more P-39 discussion than it's merits warrant.

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## nuuumannn (Jan 19, 2021)

GregP said:


> Nothing really wrong with the P-39,



Care to elaborate?



GregP said:


> but I think we've had more P-39 discussion than it's merits warrant.



Oh, I guess not, then...

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## TheMadPenguin (Jan 19, 2021)

So: B-29... suppose we built it with three R2800s per wing instead of two 3350s? 
1: About the same rated power per wing
2: Many many fewer engine-destroying mishaps with the R2800
3: Many fewer planes lost to "causes other than enemy action".

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## wuzak (Jan 19, 2021)

TheMadPenguin said:


> So: B-29... suppose we built it with three R2800s per wing instead of two 3350s?
> 1: About the same rated power per wing
> 2: Many many fewer engine-destroying mishaps with the R2800
> 3: Many fewer planes lost to "causes other than enemy action".



Suppose Fisher managed to finish the V-3420 power egg and put that in production instead of wasting their time on the XP-75.

Would the B-39 have been able to take-over from B-29 production by 1944? 

The concept being that the R-3350 could be unbolted and the V-3420 power egg bolted in its place (it contained all coolers for the engine).

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## wuzak (Jan 19, 2021)

TheMadPenguin said:


> So: B-29... suppose we built it with three R2800s per wing instead of two 3350s?
> 1: About the same rated power per wing
> 2: Many many fewer engine-destroying mishaps with the R2800
> 3: Many fewer planes lost to "causes other than enemy action".



I would gather that the B-29/6e would be heavier than the regular B-29A on account of its extra engines.


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## GrauGeist (Jan 19, 2021)

General Motors had a wide range of divisions.
The division in charge of the development of the V-3420 was Allison, the aircraft itself was being developed at Fisher, which was GM's auto body division during peacetime.

If Fisher had dropped the XP-75 project, it would have had zero effect on the V-3420 development.


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## Admiral Beez (Jan 19, 2021)

If there’s any pre-jet era FAA aircraft that desperately needed intervention it’s the Blackburn Firebrand.









Blackburn Firebrand - Wikipedia

_“In test pilot and naval aviator Captain Eric Brown's opinion the aircraft was "short of performance, sadly lacking in manoeuvrability, especially in rate of roll".[12] The position of the cockpit even with the trailing edge of the wing gave the pilot a very poor view over the nose, inhibited his ability to view his target and to land his aircraft aboard a carrier, sufficient for Brown to call it "a disaster as a deck-landing aircraft".[13]”_

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## TheMadPenguin (Jan 19, 2021)

wuzak said:


> I would gather that the B-29/6e would be heavier than the regular B-29A on account of its extra engines.


Well ... I don't have the numbers for the weights of the full-up R2800 power egg (Turbo & Super) nor the full up R3350 (Turbo & Super, but before PRT which IIRR was post-war).


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## wuzak (Jan 19, 2021)

GrauGeist said:


> General Motors had a wide range of divisions.
> The division in charge of the development of the V-3420 was Allison, the aircraft itself was being developed at Fisher, which was GM's auto body division during peacetime.
> 
> If Fisher had dropped the XP-75 project, it would have had zero effect on the V-3420 development.



Fisher designed the power egg/Quick Engine Change module for the B-19A/B-39, which used the V-3420. The QEC included oil coolers, radiators and maybe even the turbos.

Diversion of Fisher to the XP-75 slowed that development.

Allison's work on the V-3420 was changed from one with a single rotation propeller with reduction gear connected to the end of the engine, to a dual rotation propeller with extension shafts and remote gearbox.


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## GrauGeist (Jan 20, 2021)

Fisher wasn't building the engine, Allison was. They had 8 plants producing tanks, prime movers, artillery, B-25s, B-17 and B-29 parts and more.

Allison had several plants and the V-3420's development was not derailed by the Fisher project, yes, the V-3420-23 variant was going to consume resources, but it's development had other projects ear-marked too, like the XP-58, etc.


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## GregP (Jan 20, 2021)

By "nothing really wrong with the P-39" I mean the USAAC got what it ordered, and later models could have performed well if flown at high MAP. They would never have made escort or high-altitude fighters, but the P-39N was likely a decent performer if flown at 57+" MAP in combat, even at 20,000 feet. It was quite good if flown at 70+" MAP. We just didn't DO hat as a matter of standard practice like the Soviets did. As a result (along with OTHER reasons so well-described before this post in the Groundhog thread), it was not a popular airplane with the USAAC/F.

Alas, we TESTED them at higher MAP, but did not approve 75" as recommended by Ben Kelsey. I heard that the P-40 was quite a good fighter when flown at 70+" MAP from Major General (Ret) John Allison - no relation to the engine family - before he passed away. He visited Joe Yancey's shop and Joe let him start an Allison and run it. He had an ear-to-ear grin. When he demonstrated the P-40 under Tex Hill, he used 70" MAP, according to Gen. Allison. I have no reason to doubt that and he knew exactly what MAP he could run without major damage to the engine. He was comforrtable with the V-1710 even after many years of not seeing or operating one.


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## wuzak (Jan 20, 2021)

GrauGeist said:


> Fisher wasn't building the engine, Allison was. They had 8 plants producing tanks, prime movers, artillery, B-25s, B-17 and B-29 parts and more.
> 
> Allison had several plants and *the V-3420's development was not derailed by the Fisher project*, yes, the V-3420-23 variant was going to consume resources, but it's development had other projects ear-marked too, like the XP-58, etc.



I didn't say that V-3420 engine development was affected by the XP-75 program, but the V-3420 QEC for the B-39 that Fisher was developing.

If the B-39 had gone ahead Allison may have been able to justify dedicating more resources to it. As it was, the V-3420 was an on-again, off-again project for Allison due to the USAAF continually changing its mind.


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## GrauGeist (Jan 20, 2021)

wuzak said:


> due to the USAAF continually changing its mind.


Ever notice how many proposals were hijacked by the very people who issued the proposals in the first place?

I know it's popular to poke sticks at the RLM (and rightly so), but the USAAF, USN and even the Air Ministry were the assassins of many potential aircraft types.


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## wuzak (Jan 20, 2021)

btw, the XP-75 caused a delay of the first flight of the XB-39 by about a year.


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## GregP (Jan 20, 2021)

When I was working at Motorola in electronic engineering, almost all of the cost bumps and overruns were the direct result of the customer (DOD in one guise or another) asking for a change from what was tested, on order, and in production. What gets me is that most of the "changes" could have and should have been anticipated in the first place.

It's like they ask for somethng basic thinking it can't be done, and then, when it gets developed, they want all these "add ons" instead of thinking about, "What if they CAN develop this weapon? What might we want added to the basic device?" A little bit of that would go a long way to controlling cost escalations due solely to government change requests to production line items.

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## ThomasP (Jan 20, 2021)

Hey GregP,

I think your last post is a large part of the answer to the current discussion "Motivations for the Creation of RAND"

Maybe?


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## GrauGeist (Jan 20, 2021)

GregP said:


> When I was working at Motorola in electronic engineering, almost all of the cost bumps and overruns were the direct result of the customer (DOD in one guise or another) asking for a change from what was tested, on order, and in production. What gets me is that most of the "changes" could have and should have been anticipated in the first place.
> 
> It's like they ask for somethng basic thinking it can't be done, and then, when it gets developed, they want all these "add ons" instead of thinking about, "What if they CAN develop this weapon? What might we want added to the basic device?" Al little bit of that would go a long way tyo controlling cost escalations due solely to government change requests to production line items.


When I was in charge of the automotive department of the Telecomm company I worked for, we would bid out for public safety vehicle outfitting based on the agencies' equirements (push-bumper, console, partition, lightbar, two-way, etc.) and 9 times out of 10, the customer would want something changed midstream, which would of course create delays, cost over-runs and finger pointing.

Why none of those changed/upgrades were drafted into the original proposal BEFORE things got rolling, is beyond me.

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## GregP (Jan 20, 2021)

It's also the sofware engineer's lament. They ask you to write some software to do something and, when it is finished, THEN they start asking for add-ons. Guaranteed.

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## SaparotRob (Jan 20, 2021)

GregP said:


> It's also the sofware engineer's lament. They ask you to write some software to do something and, when it is finished, THEN they start asking for add-ons. Guaranteed.


And to help us set up our printers.

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## Admiral Beez (Jan 20, 2021)

pbehn said:


> If you look at any Spitfire or Hurricane pilot sat in the cockpit, it is impossible to tighten the straps enough to stop your head hitting it in a hard landing, some pilots like Bob Doe almost lost their face and were out for months if not permanently. meninroad: “© IWM (HU 54419) Portrait of a sergeant pilot of No. 610 Squadron, sitting in the cockpit of a Spitfire, … | Battle of britain, Fighter pilot, Luftwaffe
> 
> View attachment 609376


I wonder if Seafire or Sea Hurricane pilots smacked their heads when catching the wire? You're going from about 80 knots relative to carrier speed, to zero in seconds.


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## P-39 Expert (Jan 20, 2021)

GregP said:


> By "nothing really wrong with the P-39" I mean the USAAC got what it ordered, and later models could have performed well if flown at high MAP. They would never have made escort or high-altitude fighters, but the P-39N was likely a decent performer if flown at 57+" MAP in combat, even at 20,000 feet. It was quite good if flown at 70+" MAP. We just didn't DO hat as a matter of standard practice like the Soviets did. As a result (along with OTHER reasons so well-described before this post in the Groundhog thread), it was not a popular airplane with the USAAC/F.
> 
> Alas, we TESTED them at higher MAP, but did not approve 75" as recommended by Ben Kelsey. I heard that the P-40 was quite a good fighter when flown at 70+" MAP from Major General (Ret) John Allison - no relation to the engine family - before he passed away. He visited Joe Yancey's shop and Joe let him start an Allison and run it. He had an ear-to-ear grin. When he demonstrated the P-40 under Tex Hill, he used 70" MAP, according to Gen. Allison. I have no reason to doubt that and he knew exactly what MAP he could run without major damage to the engine. He was comforrtable with the V-1710 even after many years of not seeing or operating one.

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## Admiral Beez (Jan 20, 2021)

GregP said:


> Nothing really wrong with the P-39, but I think we've had more P-39 discussion than it's merits warrant.


Damn straight. Is there a way to filter out P-39 chat within a thread?

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## GrauGeist (Jan 20, 2021)

Admiral Beez said:


> Damn straight. Is there a way to filter out P-39 chat within a thread?


It'll pass in time.
Every so often this sort of thing comes up - before the P-39, it was a P-40 discussion if I remember right, that ran well past it's point of being useful.

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## swampyankee (Jan 20, 2021)

Back to how aircraft could be made better....
*
F4U Corsair:* floorboards under cockpit and some seat adjustments so somebody shorter than a 75th percentile male would fit properly

*Single-engine fighters in general:* Standardize on cockpit layout. Bluntly, it's not exactly rocket science to have the instruments and controls in similar locations on different aircraft.

*P-38:* Put generators on both engines (the aircraft had Curtiss Electric propellers. It needed electricity to fly)

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## GregP (Jan 20, 2021)

Regarding Post #1059:

The top fighter in the Pacific flown at military power loaded for combat against the bottom fighter flown at WER and light enough to be useless on a mission?

That's useful! Thanks!

You'd be a lot better off and a lot more believable if you stick to the numbers from the Pilot's Operating Handbook rather than lightweight WER tests. The P-39N was nowhere NEAR what you posted when it was flown at normal weihgts and Normal power settings.

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## tyrodtom (Jan 20, 2021)

GregP said:


> Regarding Post #1059:
> 
> The top fighter in the Pacific flown at military power loaded for combat against the bottom fighter flown at WER and light enough to be useless on a mission?
> 
> ...



You wasting your breath. well, not really breath, but typing skills.
He's already been told that how many times ?

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## GregP (Jan 21, 2021)

Yeah, I suppose you are correct. Ah well ... one retains hope.

Cheers, Tyrodtom. And no P-39s, unless you REALLY want one.


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## P-39 Expert (Jan 21, 2021)

GregP said:


> Regarding Post #1059:
> 
> The top fighter in the Pacific flown at military power loaded for combat against the bottom fighter flown at WER and light enough to be useless on a mission?
> 
> ...


P-39 weight was listed at average weight for a flight, fully loaded with half fuel. Took off with full fuel, landed with minimum reserve. British used 95% of gross weight to allow for fuel burn. Hellcat flown at WER, as was P-39 except no WER above 17000ft. Standard tests for AAF and USN.

Pilot's manual was a guide for pilots, not the results of a performance test. Climb (and range) almost always lower in the manual than on an official test to give the pilot a reserve. Hellcat manual had no similar climb chart, only listed time to climb with no feet per minute figures at different altitudes.


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## PAT303 (Jan 21, 2021)

P-39 Expert said:


> P-39 weight was listed at average weight for a flight, fully loaded with half fuel. Took off with full fuel, landed with minimum reserve. British used 95% of gross weight to allow for fuel burn. Hellcat flown at WER, as was P-39 except no WER above 17000ft. Standard tests for AAF and USN.
> 
> Pilot's manual was a guide for pilots, not the results of a performance test. Climb (and range) almost always lower in the manual than on an official test to give the pilot a reserve. Hellcat manual had no similar climb chart, only listed time to climb with no feet per minute figures at different altitudes.



If the P39 was all the things you claim it was it would have been used across all theatres in all roles like all the great fighters were, Spitfire, Hurricane, Me109, FW190, P40, P47, P51, Wildcat Hellcat the list goes on, the P39 was a donkey in a world of thoroughbreds, move along people, nothing to see.

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## Admiral Beez (Jan 21, 2021)

swampyankee said:


> *F4U Corsair:* floorboards under cockpit and some seat adjustments so somebody shorter than a 75th percentile male would fit properly


Doesn’t the P-47 have the same issue? I’d probably drop my Big League Chew into the bowels of the aircraft.

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## GrauGeist (Jan 21, 2021)

Wasn't there was a joke about the P-47's cockpit size, I believe came from the RAF?
Something like: "When bounced by the Germans, you could run around and hide."


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## GregP (Jan 21, 2021)

Hi P-39 Expert,

OK, P-39 Expert, let’s take a look at it.

I’ll use a P-39N-1 at 7,514 lbs. That’s basic airplane plus full internal fuel (87 gallons) and no center tank. Let’s say we cruise at 15,000 feet.

1) Takeoff and climb to 5,000 feet uses 20 gallons and gets you 5.42 miles from brake release. You can do the math.

2) Climb from 5,000 feet to 15,000 feet takes 4.7 minutes at 142 gal/hrs and uses another 11.12 gallons. It also gets you another 11.714 miles from brake release.

3) Let’s say you have an action sorties in which you are at combat power for 6 minutes. You basically don’t go anywhere, but you use 13.80 gallons of fuel.

4) Now, instantly, you go from combat to cruise flight and you choose to cruise at 2,200 rpm, 31” MAP, for a fuel burn of 59 gallons per hour. That means you have 42.79 minutes of flight at 247 mph, which means another 176.15 miles.

5) So, the total range is 193.28 miles from brake release, or less than 100 miles out and back. In the Pacific, that means the P-39 was a viable airplane on full internal fuel and no aux fuel if it was flying between the islands in Hawaii. If you don’t engage in any combat, the range goes up to 251 miles under the above conditions. The conditions do not allow for fuel reserve.

Not very useful. You can get out 300 – 345 miles if you cruise at absolute economy power. But, getting caught cruising at 194 mph by a Zero means you are right in the middle of his best-performance airspeed range. Not a good place to be if you are the P-39 pilot. If you cruise at 250 mph, your range is less than 250 miles one-way, which means a 125-mile mission range.

Again, not very useful when the Pacific Ocean is your playground. You can get as many as 430 statute miles, but you’ll be cruising at 160 - 194 mph, so don’t get caught by a Zero (or any other Japanese fighter). If you DO happen to need 5 minutes of combat, and you are out at the max range, you won’t get back home before running out of fuel. The range tables don’t allow for combat.

With the 75-gallon aux tank, you can get out to 694 miles, but that is at best economy power and low-speed (160 – 194 mph) cruise, with no allowance for combat. To actually get to the max range, you’d have to basically fly the entire mission at best economy cruise power (2,000 rpm). Nobody who wanted to live would go into a potential combat area where he expected to see enemy aircraft at economy cruise. So, the max range is basically a ferry flight with no combat.

So, the P-39 looks like it could be a useful fighter for local defense and short-range attacks. That only helps offensively if there are short-range targets around. In the Pacific, there were in some island chains, notably around Port Moresby and similar island chains. Not so much if you were flying out of an island with nothing around for hundreds of miles. 

In total, it doesn't look very useful, and it didn't prove to be so in real life during WWII in the Pacific. 

In the Russian steppes, the targets could be only a few miles or a few tens of miles away, so it wasn't range-limited and the space between the launch airfield and the target was ground and not water. That meant if you had to get out of the P-39, you could walk home if you had to. A completely different scenario from the Pacific where going down might mean a LONG swim. Heck, in a flight suit a 100-foot swim was a long one.

The above come from the POH, not the lightweight WER test report.

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## GregP (Jan 21, 2021)

Hi Graugeist,

I hear they said you could take evasive acion by jumping about in the cockpit. 

But it all means the same thing, the P-47 was a LARGE aircraft if you were coming from a Spitfire. 

When I got into a P-47D, the size of the cockpit was a surprise, It was large and comfortable compared with any other fighter. The smallest cockpit I've been in is a Messerschmitt Bf 109 (actually a Hispano Ha.1112 Buchon; same as a Bf 109). If you aren't claustrophobic, you might get that way in a Bf 109. An F4U Corsair is pretty roomy, but if you drop anything (like a map or a pencil) it will likely fall into the belly and get tangled in the control cables.

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## GrauGeist (Jan 21, 2021)

I've been in the cockpit of a Bf109E (it was hangared in Chino back in the 70's) and it was certainly a tight fit - even though I was in my late teens, I stood 6'1" and there was almost zero room between the canopy ceiling and my head. I have no idea how those guys did it!
I have also been in the cockpit of an SNJ, and it's also a pretty tight fit, although it had better elbow room than a 109

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## P-39 Expert (Jan 21, 2021)

GregP said:


> Hi P-39 Expert,
> 
> OK, P-39 Expert, let’s take a look at it.
> 
> ...


You're doing this the hard way. Straight from the pilot's manual. If range is important then use the full 120gal internal, we're in the Pacific, not the Russian steppes. And lets cruise at 20000ft just in case we do get jumped by Zeros. Deduct 20gal for takeoff and climb to 5000ft, 32gal for a full 20minutes of combat at 20000ft, and a 10gal reserve for landing. That leaves us with 58gal for cruise out and back at 35gph or 1.7 hours at 224mph TAS is 380miles. Not 193. That's with a full 20 minutes at combat power at 20000ft.

Now virtually every mission was a drop tank mission so let's use the 110gal external tank most common in the Pacific. And let's go on up to 25000ft in case we meet any Zeros. Start with 230gal (120+110) less the same 20gal for takeoff, 24gal for combat at 25000ft and landing reserve of 10 gal. That leaves 176gal for cruising at 62gph or 2.8hours of cruising time at 276mph or 772miles. Full 20min combat at 25000ft and a 10gal landing reserve. 

The F6F-3 stat sheet shows a combat radius of 335mi with a 150gal drop tank, but the USN figured theirs differently. Figured like an army mission use 400gal (250 internal and 150 drop) less 45gal takeoff and climb to 5000ft, 93gal for 20 min combat at 25000ft and a 20gal reserve for landing. That leaves 242gal for cruising at 93gph (max cruise) or 2.6hours. About the same as the P-39N at 2.8hrs. Max cruise is not max continuous (normal) which used 250gph at 25000ft, that would give you less than 1hr.


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## PAT303 (Jan 21, 2021)

P-39 Expert said:


> You're doing this the hard way. Straight from the pilot's manual. If range is important then use the full 120gal internal, we're in the Pacific, not the Russian steppes. And lets cruise at 20000ft just in case we do get jumped by Zeros. Deduct 20gal for takeoff and climb to 5000ft, 32gal for a full 20minutes of combat at 20000ft, and a 10gal reserve for landing. That leaves us with 58gal for cruise out and back at 35gph or 1.7 hours at 224mph TAS is 380miles. Not 193. That's with a full 20 minutes at combat power at 20000ft.
> 
> Now virtually every mission was a drop tank mission so let's use the 110gal external tank most common in the Pacific. And let's go on up to 25000ft in case we meet any Zeros. Start with 230gal (120+110) less the same 20gal for takeoff, 24gal for combat at 25000ft and landing reserve of 10 gal. That leaves 176gal for cruising at 62gph or 2.8hours of cruising time at 276mph or 772miles. Full 20min combat at 25000ft and a 10gal landing reserve.
> 
> The F6F-3 stat sheet shows a combat radius of 335mi with a 150gal drop tank, but the USN figured theirs differently. Figured like an army mission use 400gal (250 internal and 150 drop) less 45gal takeoff and climb to 5000ft, 93gal for 20 min combat at 25000ft and a 20gal reserve for landing. That leaves 242gal for cruising at 93gph (max cruise) or 2.6hours. About the same as the P-39N at 2.8hrs. Max cruise is not max continuous (normal) which used 250gph at 25000ft, that would give you less than 1hr.



So if all this was true why didn't at happen Expert, why did the US leave their most valuable A6M killer back in the states or used it for secondary roles when quite clearly it would have turned the tide in the Pacific?.

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## GregP (Jan 21, 2021)

I wasn't doing it the hard way, I was using the Pilot's Operating Handbook, which the REAL pilots would have been using, and which YOU should be using, too.

My P-39N POH says full internal fuel is 87 gallons. Could be that later P-39Ns had 120 gal, I won't look it up, but I thought the P-39Q-5 was the one with full internal tanks restored after they had been reduced to 87 gallons. Maybe I disremember and maybe you do. If they DID have 120 gallons, you had 32 more gallons, which would last for 133 more miles at fast cruise, 67 more miles combat range because you have to fly back. Still isn't very impressive and isn't likely to get that way ... they are long out of service and there isn't much chance of them doing better in another war.

The F6F Hellcat was the best fighter, in terms of enemy aircraft shot down, in the Pacific, so I won't really bother with analyzing it; go look at the POH. It stands upon merit. The fact that is WAS the best at shooting down enemy aircraft is no doubt due to the US Navy holding off approving the F4U for carrier operations until the British embarrassed them by approving it for their own carriers, forcing the Navy to "save face" and ALSO use it that way. As a result, the early Corsairs were used from ground bases by the Marines and weren't living in the target-rich environment of a front-line WWII U.S. carrier fighter in the Pacific. In point of fact, the Corsair was also a VERY good fighter and would have held its own or even have been the best had it been deployed at the same time to carriers. Again, it stands upon earned merits.

The P-39 has no such merits in U.S. or British service and thus should be looked at with some scrutiny since it had short-range and didn't prove very good at air comat in U.S. or British service. Now, had we been fighting ourselves over, say, Nebraska, where targets were close and there was gound under the belly, it might have been fine. It wasn't over water at longer ranges. About the ground part, the P-39 didn't do very well in Europe where there WAS ground under the belly. In the ETO, it was removed from service by the British and sent to obscrure low-priority fronts, like North Africa and the Med, where it ALSO didn't do very well. It did OK in Russian service, but that isn't my country and it didn't do well for us.

And, if you use a 110-gallon drop tank, you drop it before combat, so all the extra fuel is dependent upon NOT finding combat. If you are flying P-39s, you are, or SHOULD be, based close to your targets or you won't get there and back. At least with the P-51 in Europe, if they dropped tanks, there was enough range to fight combat and get home even if they DID abandon escort to make it home.

You are beating a dead horse, guy, and it isn't going to get any better.

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## Milosh (Jan 21, 2021)

P-39 Expert said:


> Now virtually every mission was a drop tank mission so let's use the 110gal external tank most common in the Pacific. And let's go on up to 25000ft in case we meet any Zeros. Start with 230gal (120+110) less the same 20gal for takeoff, 24gal for combat at 25000ft and landing reserve of 10 gal. That leaves 176gal for cruising at 62gph or 2.8hours of cruising time at 276mph or 772miles. Full 20min combat at 25000ft and a 10gal landing reserve.



Are you saying the P-39 went into combat with the 110gal drop tank still attached?

P39FOIC.pdf (zenoswarbirdvideos.com)
P39TOCLC.pdf (zenoswarbirdvideos.com)


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## Shortround6 (Jan 21, 2021)

It also tends to gloss over details.

If you want to use 95% of the gross weight for the performance, fine use it.
*BUT* make sure the plane you are comparing to is also at 95% and not 100-102% 
The P-39N will still beat the F6F-3, just not by as much.

Lets also consider than some of the P-39Ns (the early ones) were delivered with 87 gallon fuel tanks. There was no just fill them up with 120 gallons internal fuel for certain missions.
Later P-39Ns got the 120 gallon fuel tanks restored and some of the ones in the field were refitted. 
Part of the reason for this was to get rid of the weight of the self sealing fuel cells holding the last 33 gallons. 
You also don't "just" add drop tanks and presto-chango get quite the boost in range you are calculating. Just adding the 75 gallon tank cost the P-39Q 2-5 gallons in climb to height. Adding another 210-225lbs might cost a few more gallons just for the climb.

and then we have the _HUGE _problem of the P-39 having no combat power rating at 20,000ft. It doesn't even have a full military power rating. Sure you can run it at 3000rpm but the supercharger will NOT supply even the 44.5in of MAP for military power. The engine can only make about 880-885 hp at 3000rpm. This is the big reason it has such good range at 20,000ft.
The engine isn't making any power. Even worse at 25,000ft. 

It doesn't matter how much fuel you can strap underneath. What matters is trying to fight on internal fuel (minus warm up and take-off) and then how much fuel is left in the internal tanks for the trip home. You don't fight with drop tanks attached ( well the Japanese did but..........) 

At 25,000ft the P-39 has about 725hp available running at 3000rpm and wide open throttle. 

I would also like to see the Flight operation instruction chart for the P-39 with the 110 gallon tank attached. 

P-39Q-1 with the gun pods could only do 267mph true at 25,000ft with the tank attached at 2600rpm and wide open throttle. 

I would like to know how or why the F6F-3 used up 45 gallons getting to 5,000ft. Corsair with basically the same engine only used up 22 gallons to take-off and climb to 5,000ft with a gross weight of 14,200lbs.


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## Milosh (Jan 21, 2021)

Weight and Balance chart for the P-39Q, P39WBC.pdf (zenoswarbirdvideos.com)


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## nuuumannn (Jan 21, 2021)

P-39 Expert said:


> And let's go on up to 25000ft in case we meet any Zeros.



Actual fly-off tests between A6Ms and P-39s proved that anything above 15,000 feet and the P-39 is outclassed by the Zero. Trials using a P-39D against a Zero 21 in August 1942, admittedly an earlier model than the 'N although the 'D model was what was on the frontline at the time, shows that anything above 12,500 feet and it is left behind. During this particular fly-off, the trial had to be called off because the P-39 was low on fuel, and that was during a trial fly-off under controlled conditions. During similar fly-offs with F4U, F4F, P-38 and P-51, no other aircraft ran out of fuel.

The F6F however during later trials against a Zero 52 in 1944 proved that above 14,000 feet it was superior in every way, below that height up to 9,000 feet the Zero was faster, but between 9 and 14,000 ft the F6F gradually caught up. The F6F-5 model however was superior in speed to the Zero 52 at _all_ altitudes.

No comparison between the F6F and the P-39 as combat aircraft, to be honest. One is clearly superior to t'other, and their relevant combat histories prove that beyond doubt.

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## Shortround6 (Jan 21, 2021)

The F6F-3 could also use it's full power with less chance of cooking the engine on a hot day. 

The tests for the P-39N were done on two days, one a bit hotter than a "standard day" temp was about 39 degrees F at 11,000ft when the "standard" called for 19.8.

However the 2nd test report on the same airplane was done on a day when the outside temp was -12 degrees C (10.4 degrees F) at 12,000ft and the plane was judged not acceptable as the estimated temperature on a "hot day" would have been 152 degrees C (305.6 degrees F). 
The engine was running about 10 degrees C cooler than the earlier test. 

WEP isn't much use if you can't use in the tropics or dessert conditions "Hey, Germans, could you only please attack just about at dawn (coolest part of the day) so our engines won't overheat trying to climb up for the intercept, please, please?"

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## nuuumannn (Jan 21, 2021)

Shortround6 said:


> WEP isn't much use if you can't use in the tropics or *dessert* conditions



No, the P-39N gives you notoriously bad digestion straight after the main course. 

Not only that, but according to the reports on the 'N model under trial conditions is the following statement; "Airplane does not meet Air Corps cooling requirements at any of these powers."

Here: Memorandum Report on P-39N-1, A.C. No. 42-4400 (wwiiaircraftperformance.org)

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## pbehn (Jan 21, 2021)

I think we have another groundhog infestation?

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## P-39 Expert (Jan 21, 2021)

PAT303 said:


> So if all this was true why didn't at happen Expert, why did the US leave their most valuable A6M killer back in the states or used it for secondary roles when quite clearly it would have turned the tide in the Pacific?.


The 1942 P-39s (D/F/K/L) were very overweight for the power available (V-1710-35/63) and had a hard time cruising over 18000ft with the ever-present drop tank. Almost every combat with the A6M2 Zero or Ki-43 Oscar began with the Japanese planes making a firing pass from above. Not fun. At all. Those 1942 P-39s did fight the Japanese planes to a draw despite inexperienced pilots because they were about 40mph faster and had armor protection. But pilots hated them (along with the P-40) because they had to give the Japanese the first punch, and intercepting high flying Japanese bombers (18000-22000ft) was an iffy proposition.

The decision had already been made by the AAF brass that the war would be fought with turbocharged P-38 Lightnings and P-47 Thunderbolts. Problem was they didn't have enough of them yet until the P-38F/G got into combat in very late 1942 and the P-47C in April 1943. The P-39 and P-40 would be exported under lend-lease to our allies or used for training by the AAF.

By November 1942 the -85 engine with the 9.6 supercharger gears was in the P-39N which was the best performing model of the P-39 series. It was faster under 20000ft and would outclimb and out turn both the early P-38F/G and the P-47C/D. It dived better than the P-38 and had about the same endurance as the P-47. Ceiling was competitive with both. And the P-39 was inexpensive compared to the ultra-expensive Lightnings and Thunderbolts. But the AAF had four fighters in production and the Merlin P-51 was being put into production too. 

The P-39 (and P-40) would have benefitted from the two stage -93 engine that was in production in April 1943. But the field was crowded and the decision had been made to emphasize the turbo P-38 and P-47.


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## nuuumannn (Jan 21, 2021)

As I pointed out, at the time of those trials in August 1942, frontline P-39 units were using the 'D model, not the 'N model. And despite the P-39N's obvious advantages compared to the earlier models, by 1944, when the P-39N has reached the frontline and had been equipping for around a year, the P-38, P-47 and P-51 were the AAF's primary fighters across both the PTO and ETO. That the P-39 remained in service beyond 1943 was down to the numbers game - the AAF needed fighters and the P-39 was available, warts 'n all. If the AAF _could_ have equipped all its P-39 units with _any_ of the other fighters it probably would have. They offered significant advantages over their enemies the P-39 did not possess.


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## Shortround6 (Jan 21, 2021)

You have about 3 things going on in late 1942, maybe more.

1, the change to the 9.60 supercharger gears on the single speed/single stage Allison. These are not magic, they do improve altitude performance by about 4,000ft. (What plane powered by the older engines could do at 13,500 it could now do at 17,500) which is not enough to make the P-40 and P-39 effective fighters at 20,000ft and above unless they lost a _LOT_ of weight.
2. The US was late to party when it came to overboosting engines. A lot of testing was going on, some squadrons were overboosting in the field. _Officially_ The US did not approve over boosting until Dec of 1942 (after the tests of the P-39N).
3. It took the US about 3 to 6 months to get a fighter from the factory door to an operational combat unit overseas. In the case of the P-39N the first ones rolled out the door in Nov 1942, They showed up in North Africa in April (?) of 1943 and at Henderson field in June of 194*3*. Shipping space arrangements and allocations of aircraft were often made before the actual planes rolled out the door.

Decisions as to which planes to send where in the first part of 1943 were made before the test flights of the P-39N. And the test flights using WEP settings in the P-39N showed some serious problems. THE USAAF and Allison called for a max cooling temperature of 250 degrees F or 121 degrees C .

We may well consider that P-39 use the Soviet union was quite different due to the Soviets acceptance of lower service life between overhauls and the usually colder temperatures the engines were operating in. You could get hot temperatures in southern Russia in the summer but lets face it, The P-39N was overheating using WEP in Buffalo New York in Oct and barely exceeding the allowable in limit in November.

Correction from Wuzak

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## wuzak (Jan 21, 2021)

Shortround6 said:


> 3. It took the US about 3 to 6 months to get a fighter from the factory door to an operational combat unit overseas. In the case of the P-39N the first ones rolled out the door in Nov 1942, They showed up in North Africa in April (?) of 1943 and at Henderson field in *June of 1942*.



Either that was a type or Henderson Field was using a time machine.


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## wuzak (Jan 21, 2021)

P-39 Expert said:


> The P-39 (and P-40) would have benefitted from the two stage -93 engine that was in production in April 1943. But the field was crowded and the decision had been made to emphasize the turbo P-38 and P-47.



In production and available in meaningful numbers are two different things.

In any case, Bell was working on the P-63 to use the 2 stage engine.

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## BiffF15 (Jan 21, 2021)

swampyankee said:


> Back to how aircraft could be made better....
> 
> *F4U Corsair:* floorboards under cockpit and some seat adjustments so somebody shorter than a 75th percentile male would fit properly
> 
> ...



SwampYankee,

I can't help but agree that all three of your points are good. However, point number 2 has always dumbfounded me. It would have made transition from one to the next much easier and safer.

Cheers,
Biff


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## swampyankee (Jan 21, 2021)

BiffF15 said:


> SwampYankee,
> 
> I can't help but agree that all three of your points are good. However, point number 2 has always dumbfounded me. It would have made transition from one to the next much easier and safer.
> 
> ...



Thank you.

Panel design is something where, I think, the NACA, USAAC/USAAF and USN could have actually agreed on in the early 1930s. A lot of the panel designs looked like something a drunken frat boy puked up after a hard night of drinking.


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## Shortround6 (Jan 21, 2021)

wuzak said:


> In production and available in meaningful numbers are two different things.
> 
> In any case, Bell was working on the P-63 to use the 2 stage engine.



It took until the fall of 1943 to clear the 2 stage engine for WEP ratings. This including things like the new keystone piston rings. 

Without the WEP/water injection the V-1710-93 engine was rated at 1180hp at 21,000ft 
which is about 200hp less at 2,500ft lower than the Merlin 61 of spring/summer of 1942, one year earlier. 

First P-63s built with the engine flew under restrictions until the engine was cleared.


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## BiffF15 (Jan 21, 2021)

swampyankee said:


> Thank you.
> 
> Panel design is something where, I think, the NACA, USAAC/USAAF and USN could have actually agreed on in the early 1930s. A lot of the panel designs looked like something a drunken frat boy puked up after a hard night of drinking.



I have attached the cockpit panel of the mighty T-37 Tweet. This nightmare was in use into the 2000's. Plane was designed for day visual flight rules and morphed into a full Instrument Flight Rules (IFR) jet. Oh, and it held very little fuel. But at least it was loud, and the A/C sucked...

Cheers,
Biff

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## GregP (Jan 21, 2021)

One of the big improvement they COULD have made to the F6F was to remove the dihedral from the outer wing panels. The decision was not to interrupt production to make the F6F roll much better. Instead, they developed the F8F Bearcat while producting the F6F-5. The F6F-6 was the fastest Hellcat, but they only built 2 of them ...

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## special ed (Jan 21, 2021)

A friend flew the AT-37 in VN. All sorts of interesting experiences in combat.


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## BiffF15 (Jan 21, 2021)

special ed said:


> A friend flew the AT-37 in VN. All sorts of interesting experiences in combat.



He probably flew the A-37 Dragonfly, with different engines and a whole lot more capabilities. Panel still sucked I’m sure...


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## GregP (Jan 21, 2021)

Panel DID suck, but the performance was nothing short of spectacular if you compare it with a standard T-37 dog whistle. One engine made thrust and the other one just made noise. Still, you could at least go up and spin one of them.

Here's one of them:

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## special ed (Jan 21, 2021)

From time to time while he was still in his career he would call and I'd listen to war stories. Before he retired, I asked him if it turned out as well as he hoped at the start. He said, " listen Ed, I get up and look outside and it's a beautiful day. I call ops and ask for a plane. (He was flying F-16s then). I go down check out, get in the bird they fueled, and go flying. It's great and they pay me to do it."

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## P-39 Expert (Jan 22, 2021)

GregP said:


> I wasn't doing it the hard way, I was using the Pilot's Operating Handbook, which the REAL pilots would have been using, and which YOU should be using, too.
> 
> My P-39N POH says full internal fuel is 87 gallons. Could be that later P-39Ns had 120 gal, I won't look it up, but I thought the P-39Q-5 was the one with full internal tanks restored after they had been reduced to 87 gallons. Maybe I disremember and maybe you do. If they DID have 120 gallons, you had 32 more gallons, which would last for 133 more miles at fast cruise, 67 more miles combat range because you have to fly back. Still isn't very impressive and isn't likely to get that way ... they are long out of service and there isn't much chance of them doing better in another war. *All P-39s up to the 167th N model had the normal 120 gallons. Fuel was reduced for the Russians. Kits were available to restore the full 120 gallons. The POH numbers speak for themselves.*
> 
> ...


Answers above.


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## P-39 Expert (Jan 22, 2021)

Milosh said:


> Are you saying the P-39 went into combat with the 110gal drop tank still attached?
> 
> P39FOIC.pdf (zenoswarbirdvideos.com)
> P39TOCLC.pdf (zenoswarbirdvideos.com)


Like any plane that carries a drop tank, it was dropped just prior to combat.


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## Milosh (Jan 22, 2021)

P-39 Expert said:


> Like any plane that carries a drop tank, it was dropped just prior to combat.



Did it have enough fuel to get home then? 
I suggest you look at the charts in the links posted.


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## P-39 Expert (Jan 22, 2021)

Shortround6 said:


> It also tends to gloss over details.
> 
> If you want to use 95% of the gross weight for the performance, fine use it.
> *BUT* make sure the plane you are comparing to is also at 95% and not 100-102% *That's how the AAF (and British) tested their planes. Full of fuel, but the quoted weight in the test was the average weight of the plane for that particular flight. *
> ...


See above.


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## P-39 Expert (Jan 22, 2021)

nuuumannn said:


> Actual fly-off tests between A6Ms and P-39s proved that anything above 15,000 feet and the P-39 is outclassed by the Zero. Trials using a P-39D against a Zero 21 in August 1942, admittedly an earlier model than the 'N although the 'D model was what was on the frontline at the time, shows that anything above 12,500 feet and it is left behind. During this particular fly-off, the trial had to be called off because the P-39 was low on fuel, and that was during a trial fly-off under controlled conditions. During similar fly-offs with F4U, F4F, P-38 and P-51, no other aircraft ran out of fuel. *Actually a P-39D-1, at 7850lbs the heaviest of the 1942 P-39s. Could have easily weighed 7150lbs without redundant equipment and left the Zero behind. In continuous climb from SL they were actually equal up to 14500ft when the D-1 had to reduce power to 2600rpm as it had reached the 5 minute limit. By mid 1942 that was increased to 15 minutes. Even the D-1 was faster than the Zero at all altitudes. Zero did hold more fuel than the P-39. *
> 
> The F6F however during later trials against a Zero 52 in 1944 proved that above 14,000 feet it was superior in every way, below that height up to 9,000 feet the Zero was faster, but between 9 and 14,000 ft the F6F gradually caught up. The F6F-5 model however was superior in speed to the Zero 52 at _all_ altitudes. *All P-39 models were faster than any Zero at all altitudes.*
> 
> No comparison between the F6F and the P-39 as combat aircraft, to be honest. One is clearly superior to t'other, and their relevant combat histories prove that beyond doubt. *See the attached comparison chart, and please note that the P-39N was out of production before the F6F got into combat.*


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## P-39 Expert (Jan 22, 2021)

Shortround6 said:


> The F6F-3 could also use it's full power with less chance of cooking the engine on a hot day.
> 
> The tests for the P-39N were done on two days, one a bit hotter than a "standard day" temp was about 39 degrees F at 11,000ft when the "standard" called for 19.8.
> 
> ...


Performance tests were converted to standard day conditions. Opposing planes in combat were flying in the same weather conditions, the faster plane in standard tests would still be faster on a hot day. 1943 P-38 and P-47 overheated at combat power settings. Apparently they all made do.


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## P-39 Expert (Jan 22, 2021)

Shortround6 said:


> It took until the fall of 1943 to clear the 2 stage engine for WEP ratings. This including things like the new keystone piston rings. *What's the hurry, the P-63 airframe wasn't ready until October. They were going to the Russians anyway.*
> 
> Without the WEP/water injection the V-1710-93 engine was rated at 1180hp at 21,000ft
> which is about 200hp less at 2,500ft lower than the Merlin 61 of spring/summer of 1942, one year earlier. *Merlin made more power but wouldn't fit into a P-39 or P-63. Put the -93 into a P-39 in April 1943. Give up on the intercooler and move the carb from the auxiliary stage to the normal position on the engine stage. Now you have 1150hp at 25000ft. Don't worry about WEP, just use military power. No need for intercooling or water injection. No need for the P-63 either.*
> ...


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## P-39 Expert (Jan 22, 2021)

Double post.


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## P-39 Expert (Jan 22, 2021)

Milosh said:


> Did it have enough fuel to get home then?
> I suggest you look at the charts in the links posted.


Any plane has enough fuel to get home as long as the capacity of the drop tank is less than the internal fuel.


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## pbehn (Jan 22, 2021)

P-39 Expert said:


> Any plane has enough fuel to get home as long as the capacity of the drop tank is less than the internal fuel.


Only if you ignore the fuel used in combat. A Merlin consumed about three times as much fuel on maximum power compared to economic cruise (150 gal/hr against 50 gal/ hr), I have no reason to think an Allison engine would be much different.


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## Milosh (Jan 22, 2021)

fuel consumption
P39SEFC.pdf (zenoswarbirdvideos.com) 

war emergency: 170g/h

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## P-39 Expert (Jan 22, 2021)

pbehn said:


> Only if you ignore the fuel used in combat. A Merlin consumed about three times as much fuel on maximum power compared to economic cruise (150 gal/hr against 50 gal/ hr), I have no reason to think an Allison engine would be much different.


In planning your mission you have already deducted reserves for takeoff, combat and landing from total fuel. Use your drop tank for warmup and taxi, switch to internal for the actual takeoff, then back to the drop tank asap (normally less than a minute) so that your internal fuel should be almost full. After dropping the external tank (or turning for home if there is no combat) you should have full internal fuel including reserves for combat and landing. If there is no combat and landing goes smoothly there will still be the reserves for combat and landing in your internal tank.


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## Milosh (Jan 22, 2021)




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## P-39 Expert (Jan 22, 2021)

Milosh said:


> View attachment 609816


Interesting, I had seen this chart before and the -63/83/85/93 engines had military power for 15 minutes but the original -35 was still rated for only 5 minutes even though it had a war emergency rating from late 1942.


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## pbehn (Jan 22, 2021)

P-39 Expert said:


> In planning your mission you have already deducted reserves for takeoff, combat and landing from total fuel. Use your drop tank for warmup and taxi, switch to internal for the actual takeoff, then back to the drop tank asap (normally less than a minute) so that your internal fuel should be almost full. After dropping the external tank (or turning for home if there is no combat) you should have full internal fuel including reserves for combat and landing. If there is no combat and landing goes smoothly there will still be the reserves for combat and landing in your internal tank.


That is a different issue, if you fly to a point using only a 110 gal drop tank, then use your internal tank for 15 mins @ 170 gal/hr how much internal fuel do you have left? Will it get you back as far as your external tank took you?


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## GregP (Jan 22, 2021)

I make a motion we improve the forum by avioding the P-39 until such time as real-world use and results come into play.

If you look at aerial victories by type and theater, the legacy of the P-39 becomes apparent. First, let’s remove the essentially non-participating fighters like the P-26, P-35, P-36, P-43, P-70, F2A, Beaufighter (lend-lease), TBF/TBM, P-61, and the SBD. That leaves the P-38, P-39, P-40, P-47, and P-51 (including F-6 and A-36), F4F/FM-2, F6F, and F4U, and Spitfire (only the MTO) which is most of our fighters.

If we just look at the Pacific, the Spitfire wasn’t used by the U.S.A. and it drops out. The Lowest total victories is 288 by the P-39/P-400. Next would be 297 by the P-51 since it got to the Pacific essentially at the end of the war. The FM-2 is next at 422, followed by the P-40 with 661. It continues going up from there.

If we get out of the Pacific only and look at the entire war, the lowest victory tally is 321 by the P-39 / P-400, followed by the Spitfire in the MTO/ETO with 379, and it goes up from there.

The Mosquito, P-26, P-35, P-36, P-43, P-70, F2A, and Beaufighter only scored 58 victories combined, so they don’t really count as major fighters in service with the U.S.A. . The TBF/TBM outscored them all combined with 98 victories, but isn’t a fighter.

So, we have had 100+ pages and all this “it could have been a great airplane” about the fighter with the lowest score of any major fighter in service with the U.S.A. . The P-51, in all theaters, scored 5,954 victories, followed by the F6F with 5,168. Why we are so concerned with the fighter with the least victories in WWII in U.S. service? It was NOT a good airplane for anything other than short-range, low-altitude missions. We didn’t fly many of those except to keep the P-39 drivers current in their airplanes.

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## pbehn (Jan 22, 2021)

GregP said:


> I make a motion we improve the forum by avioding the P-39 until such time as real-world use and results come into play.
> 
> If you look at aerial victories by type and theater, the legacy of the P-39 becomes apparent. First, let’s remove the essentially non-participating fighters like the P-26, P-35, P-36, P-43, P-70, F2A, Beaufighter (lend-lease), TBF/TBM, P-61, and the SBD. That leaves the P-38, P-39, P-40, P-47, and P-51 (including F-6 and A-36), F4F/FM-2, F6F, and F4U, and Spitfire (only the MTO) which is most of our fighters.
> 
> ...


Great post, I agree with all except the part in bold. for the USA the greatest use of the P-39 in my opinion was as an advanced trainer IN THE USA. There were 1934 accidents 369 were fatal and 865 airframes wrecked, that isnt a reflection on it as a trainer but more its level of use. Many pilots did advanced training in USA and then completed combat training "on type" in UK or elsewhere, they will not be on those statistics which are purely for USA. The accident numbers are completely out of proportion to its production numbers and combat use when compared against other US fighters. A trainer isn't a spectacular role, but someone has to do it and I can see a lot of advantages to tricycle U/C in a training centre. United States World War II Aircraft Loss Statistics during Flight Training


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## GregP (Jan 22, 2021)

Verey good point, pbehn. The P-39 was often the first fighter that new pilots flew after advanced training. Naturally, it would be one of their favorites if not THE favorite since it had much higher performance than an AT-6, which was likely the highest-performance aircraft they had fown to date in training.

I should not have left out the training use of the aircraft.

Cheers.


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## Shortround6 (Jan 22, 2021)

"If you want to use 95% of the gross weight for the performance, fine use it.
*BUT* make sure the plane you are comparing to is also at 95% and not 100-102% *That's how the AAF (and British) tested their planes. Full of fuel, but the quoted weight in the test was the average weight of the plane for that particular flight.*
The P-39N will still beat the F6F-3, just not by as much."

I have tried to point out the difference before but you are not getting it.

The chart that you keep posting for the F6F-3 with your dots for the P-39N was for the F6F-3 at* 12,500lbs*.
trouble is that the gross weight for an F6F-3 with full internal fuel and ammo was from around 12,200 to 12,450lbs depending on the exact airplane (weights did vary a few percent) and exact outfit/fittings. Plane the chart is for had three bomb racks/drop tank stations/racks. The slightly lighter "standard" planes only had the center line station.
What is the performance of the F6F-3 at *11,600lbs*? ie, 95%
Not as good as the P-39N but not as bad as your chart shows.

_"and then we have the HUGE problem of the P-39 having no combat power rating at 20,000ft. It doesn't even have a full military power rating. Sure you can run it at 3000rpm but the supercharger will NOT supply even the 44.5in of MAP for military power. The engine can only make about 880-885 hp at 3000rpm. This is the big reason it has such good range at 20,000ft.
The engine isn't making any power. Even worse at 25,000ft. _*On that paltry horsepower the P-39 still did 385mph and climbed at 2650fpm at 20000ft. At 25000ft it did 370mph and climbed at 1950fpm. For 1943 the speed is good but the climb is excellent. Look at the P-39/F6F chart."*

How about we look at the following.

Plane.................P-40N-1...............P-39M-3...............P-39N-1....................P-39Q-5.................P-51A.....................P-63A-9
weight................7413lbs................7430lbs................7274lbs......................7821lbs.................8000/7730lbs...........8950lbs.
Speed................371mph................373mph.............389.5mph....................371mph..................408mph..................400mph 
altitude............17,300ft..................15,900ft..............16,100ft.......................15,000ft....................17,500ft.................16,000ft
power................1125hp...................1125hp...............1125hp.......................1140hp......................1125hp..................1285hp

climb
15,000ft.............2680fpm................2640fpm..............3340fpm...................2840fpm..................2610fpm................3390fpm
power..................1090hp...................1040hp.................1060hp....................1050hp......................1090hp..................1360hp.
20,000ft.............1970fpm.................2000fpm..............2630fpm...................2200fpm..................1980fpm...............2660fpm
power...................905hp.....................880hp...................885hp........................882hp.........................910hp...................1175hp
25,000ft.............1400fpm.................1400fpm..............1940fpm....................1570fpm..................1350fpm................2020fpm.
power................750hp.........................725hp....................745hp.........................740hp......................760hp.....................985hp.

All except the P-63 were using Allison engines with 9.60 supercharger gears. Fuel and ammo loads seemed to vary a bit. 
Yes the P-39Q and the P-63 had the external .50 cal pods. 
The P-39 has less drag than the P-40. The P-40 and P-51 seem to have better ram effect on their inlets? 
The P-51A took off at 8000lbs but the speed ratings were at lower weight for each altitude. 

All performance should be at altitudes where the WEP settings stop having any effect. 
The P-63 is about 23% heavier than the P-39N, however the P-63 has 28-32% more power in the climb scenarios and 14% more power in the highspeed flight (it is a bigger airplane) 

The P-39N seems to have a performance way, way out of line with the other planes that cannot be explained away with just a few hundred pounds of weight.
All planes and engines are going to vary a few percent. 

You also need to figure out what a plane needs in order to maneuver at 20,000ft, while it is pretty much the same as lower altitudes things are getting further out. The stall speed is higher for one thing. You need to go faster in just level flight. Now bank 60 degrees (2 Gs) or more and if you are at anywhere near max speed you have to slow down or loose altitude. Maybe both. The lower wing loading airplanes have an advantage. 
Nobody thought the P-51A was a high altitude plane even though it could hit 395mph at 25,000ft (at 7617lbs) because it could not sustain speed in a turn or regain speed or altitude quick enough after performing manuever/s.

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## pbehn (Jan 22, 2021)

GregP said:


> Verey good point, pbehn. The P-39 was often the first fighter that new pilots flew after advanced training. Naturally, it would be one of their favorites if not THE favirote since it had much higher performance than an AT-6, which was likely the highest-performance aircraft they had fown to date in training.
> 
> I should not have left out the training use of the aircraft.
> 
> Cheers.


The same could possibly be said about the P-51B and C. If it takes 200 hours to train a pilot on type and a Merlin needs a rebuild after 250 hours plus an airframe needs an overhaul after 500 hours, how many were worn out if not actually wrecked before they took off for a combat mission?


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## Shortround6 (Jan 22, 2021)

P-39 Expert said:


> In planning your mission you have already deducted reserves for takeoff, combat and landing from total fuel. Use your drop tank for warmup and taxi, switch to internal for the actual takeoff, then back to the drop tank asap (normally less than a minute) so that your internal fuel should be almost full. After dropping the external tank (or turning for home if there is no combat) you should have full internal fuel including reserves for combat and landing. If there is no combat and landing goes smoothly there will still be the reserves for combat and landing in your internal tank.



Nobody would follow that procedure, on a routine basis, there is too much chance of error/problems. Every time you switch tanks (and the left and right tanks were selected separately, not together), there was a chance of sucking an air bubble. 
While they often did not wait until they were at 5000ft to switch over common practice was to get the landing gear retracted and get enough altitude to either restart the engine if it stopped or to turn and dead stick the plane on the runway (or alternate runway). Most planes did route the excess fuel from the carb to one of the internal tanks so that it was slowly refilled in flight, This was to whatever tank on the airplane was also the reserve tank. 
This procedure is actually more efficient because if the internal tank the return line is routed to is full the excess fuel is dumped overboard. Note that this is the only way to get fuel from the drop tank into the internal tank. 
also note that if the selector switch (five positions----off, left, right, reserve, and belly tank) is set to the right tank the left tank will slowly refill in flight, 
A long range flight could be conducted with just 5 tank switches,
1. start on reserve (left tank) switching from off. 
2. after 20 minutes change to belly tank and run dry
3. change to right tank and run dry. 
4. change to left tank and run dry.
5. change to reserve and land or bail out. 
6th change is moving the tank selector back to off when shutting down the engine. 

This is from the manual for the P-39K & L.

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## Admiral Beez (Jan 22, 2021)

GregP said:


> Hi P-39 Expert,


Damn, where’s my P-39 filter?

How about early development and adoption of three blade, variable pitch props for the Spitfire and Hurricane? This may get us to an earlier Sea Hurricane, for starters.

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## P-39 Expert (Jan 22, 2021)

Shortround6 said:


> "If you want to use 95% of the gross weight for the performance, fine use it.
> *BUT* make sure the plane you are comparing to is also at 95% and not 100-102% *That's how the AAF (and British) tested their planes. Full of fuel, but the quoted weight in the test was the average weight of the plane for that particular flight.*
> The P-39N will still beat the F6F-3, just not by as much."
> 
> ...


Expand above.


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## P-39 Expert (Jan 22, 2021)

Shortround6 said:


> Nobody would follow that procedure, on a routine basis, there is too much chance of error/problems. Every time you switch tanks (and the left and right tanks were selected separately, not together), there was a chance of sucking an air bubble.
> While they often did not wait until they were at 5000ft to switch over common practice was to get the landing gear retracted and get enough altitude to either restart the engine if it stopped or to turn and dead stick the plane on the runway (or alternate runway). Most planes did route the excess fuel from the carb to one of the internal tanks so that it was slowly refilled in flight, This was to whatever tank on the airplane was also the reserve tank.
> This procedure is actually more efficient because if the internal tank the return line is routed to is full the excess fuel is dumped overboard. Note that this is the only way to get fuel from the drop tank into the internal tank.
> also note that if the selector switch (five positions----off, left, right, reserve, and belly tank) is set to the right tank the left tank will slowly refill in flight,
> ...


All AAF fighters had multiple internal tanks and carried external tanks. Procedure was the same on all of them.


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## P-39 Expert (Jan 22, 2021)

GregP said:


> I make a motion we improve the forum by avioding the P-39 until such time as real-world use and results come into play.
> 
> If you look at aerial victories by type and theater, the legacy of the P-39 becomes apparent. First, let’s remove the essentially non-participating fighters like the P-26, P-35, P-36, P-43, P-70, F2A, Beaufighter (lend-lease), TBF/TBM, P-61, and the SBD. That leaves the P-38, P-39, P-40, P-47, and P-51 (including F-6 and A-36), F4F/FM-2, F6F, and F4U, and Spitfire (only the MTO) which is most of our fighters.
> 
> ...


P-39 shot down more planes than any other American fighter in Russian service. That was its main combat deployment.


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## pbehn (Jan 22, 2021)

Two things that always puzzle and amuse me about these discussions is that combat lasts 15 minutes, does someone ring a bell and say "time to go home" and that it ends where it starts. 360 MPH is 6 miles per minute , on average pilots may end where they start after 15 minutes but they may be anywhere in a 90 mile radius, that is 90 miles closer to base or 90 miles further away. The Fw 190 that landed in south Wales did so because its pilot didn't have a clue where he was and didn't trust his instruments to tell him. Many accounts I have read say the pilots start to figure out where they were when its over, though they may have some awareness while in combat.

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## Shortround6 (Jan 22, 2021)

P-39 Expert said:


> All AAF fighters had multiple internal tanks and carried external tanks. Procedure was the same on all of them.


 Yep and none of them used the procedure you outlined.


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## Admiral Beez (Jan 22, 2021)

pbehn said:


> Two things that always puzzle and amuse me about these discussions is that combat lasts 15 minutes, does someone ring a bell and say "time to go home" and that it ends where it starts. 360 MPH is 6 miles per minute , on average pilots may end where they start after 15 minutes but they may be anywhere in a 90 mile radius, that is 90 miles closer to base or 90 miles further away. The Fw 190 that landed in south Wales did so because its pilot didn't have a clue where he was and didn't trust his instruments to tell him. Many accounts I have read say the pilots start to figure out where they were when its over, though they may have some awareness while in combat.


I assumed combat ends when one side of the combatants are dead, disabled, out of fuel or out of ammunition.


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## Shortround6 (Jan 22, 2021)

*P-39 was the second most aerodynamic behind the P-51. Seems
logical it would be the second fastest. BTW why include the P-63?
It had a two stage engine.* 

The P-51 had the least drag, the P-39M & N next, followed by the P-39Q, the P-63 has a smaller flat plate than the P-40 despite being the largest plane of the group. 

As for the P-63, please compare to the P-39N. The P-63 climbs better by 50fpm at 15,000ft. 1.4% better. 30fpm better at 20,000ft 1.3% and 80fpm better at 25,000ft or 4%. 
Strange coincidence. 

*P-39 was the lightest of this group, logical that it had the best climb.* 

Logic climbed out the window on this one and it was on the 20th floor. 

P-39 was 98.7% as heavy as the P-39M and yet this just over 2% decrease in weight is supposed to be responsible for a 26.5% increase in climb at 15,000ft, 31.5% increase in climb at 20,000ft and a whopping 38.6% increase in climb at 25,000ft. 
If you believe that I have vacation land for sale in Florida, usable 1/2 the year (every 12 hours) 

The change in reduction gear and different prop might be worth something but the poor P-39Q-5 was faster climbing on the same power (or very slight changes) while being over 400lbs heavier than the P-39M. But compared to the N????? N is only 92.4 percent as heavy but the increase in climb is for the N is 17.6%, at 15,000, 19.5% at 20,000, 23.5% at 25,000 a lot of improvement for a 7.6% change in weight. 

The P-40, P-39M and P-51A actually track pretty well. small differences in climb with small differences in power and weight. 

Climb is pretty much dependent on power to weight _after _ you subtract out the power needed to fly at the best climbing speed (usually a bit faster than the lowest drag speed.) 
The P-40 climb speeds were the slowest of the group by about 10-20mph depending on altitude. The P-39N was actually flying a couple mph faster than the P-51A, strangely the P-39M and P-39Q, despite being a bit heavier flew just a bit slower than the P-39N. 

. *So, we have another bad test? Those Wright Field test pilots could test every plane in the AAF inventory, but somehow all their P-39 tests were wrong?* 

There are a number of typos, moved rows/columns and mislabeled headings in some of the tests and pilots manuals and data sheets. I have no idea why the P-39N numbers are so far off but something doesn't seem right.
BTW check out the manual for the P-39Q, max cruise is labeled IAS for the clean aircraft while the chart with drop tank says true airspeed in the max cruise column. 
Not a biggy but the clean airplane is supposed to do 330mph IAS at 25,000ft. 
cruise at 2600rpm is 495mph true?????
Sometimes the error is easy to spot, sometimes it is not. 
In this case a number of other charts for other airplanes give the max cruise in true airspeed and all the other columns are IAS so it was really easy to pick up on.


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## Shortround6 (Jan 22, 2021)

Admiral Beez said:


> I assumed combat ends when one side of the combatants are dead, disabled, out of fuel or out of ammunition.


 This assumes the pilot/s who are at the disadvantage have enough speed, or climb, or altitude or distance between them and their opponents to disengage without winding up first in your list. 

Pilots did push their planes past the artificial time limits, there was no clockwork mechanism (except on some 109s) that would automatically reduced power. 
However pushing the plane/engine increases the likelihood of the engine breaking down at worst and used up the fuel needed to get home at best.


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## GregP (Jan 23, 2021)

It didn't HAVE that climb rate uless they ran extra MAP. Use the POH climb rates for U.S. sevice airplanes abd service MAP levels. It sure isn't even 3,000 fpm in climb, especially at 44" MAP, and P-39s typically took off at about 8,000 lbs, not 7,500 lbs.

The statement was made that the P-39 shot down more enemy aircraft than any other American fighter in Soviet service. So, how many did it shoot down and what is the source for that statement. I have certainly seen the statement in print, have repeated it myself, but have also seen no victory figures with sources to back it up. So, its basically an unsupported statement.

Enough round words of greatness, what are the figures? I hope they imclude sorties, too. including action and non-action sorties.

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## GrauGeist (Jan 23, 2021)

And there was only one USAAF pilot who made ace while flying a P-39.

One...


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## pbehn (Jan 23, 2021)

Admiral Beez said:


> I assumed combat ends when one side of the combatants are dead, disabled, out of fuel or out of ammunition.


Only if you have a plane good enough to break off, that was the issue with a Spitfire MkV against the Fw 190. There is the other scenario, when you are relieved as an escort it is then your choice how much fuel and ammunition you use on targets of opportunity.


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## Juha3 (Jan 23, 2021)

GregP said:


> ...The statement was made that the P-39 shot down more enemy aircraft than any other American fighter in Soviet service. So, how many did it shoot down and what is the source for that statement. I have certainly seen the statement in print, have repeated it myself, but have also seen no victory figures with sources to back it up. So, its basically an unsupported statement.
> 
> Enough round words of greatness, what are the figures? I hope they imclude sorties, too. including action and non-action sorties.



I guess nobody knows, same goes to any widely used fighter, claims, even accepted claims are not the same as the real figures. But
-Stalin asked more P-39s and Spitfires, not P-40s and Hurricanes
-Three of the five top Soviet aces (Grigori Rechkalov, Nikolai Gulaev and Dmitri Glinka) got most of their kills while flying P-39s and Rechkalov and D. Glinka ended the war in May 1945 still flying P-39s with Guards units operating inside Germany. Gulaev was badly wounded in Aug 44, while still flying P-39 with 129 GIAP
The two other aces being Kozhedub (1st) (La-5, -5FN, -7) and Yevstigneyev (4th) (La-5, -5FN). 6th was Vorozheikin, I-16 and Yaks, 7th Pokryshkin
Soviets did not have high regard on the few P-51s they got and did not understand P-47, to them it was far too big and heavy to be a good fighter, and there were not many of them to be used, they were used mainly as fighter bombers IIRC.

So there are clear indicators that P-39 clearly was the most successful US fighter in the VVS service.

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## GregP (Jan 23, 2021)

Hi Juha3,

Yes, I agree. There are clear indications the P-39 did rather well in Soviet service. Just not numbers. It surely shot down more than U.S.-operated P-39's did, but there seems to be no real way to tell how many. So, that being the case, there is no real way to compare its perofrmance in Soviet hands with aircraft in U.S. service in an apples-to-apples manner.

So, any arguments are sort of based on opinions, not combat statistics. Personally, I LIKE the P-39. But 100+ pages of gushing about its virtues leaves me with a very sour opinion of the subject in general. If it was so good, why doesn't is show up in the war record? And ... we don't HAVE the Soviet war record for any of the aircraft they operated as far as I can tell.

Opinions can only really stand up for a post or two. Not 100+ pages, especially when using flight manual seems to make no dent in the performance claimed. Except for the WER tests, there is no other evidence the P-39 could climb so well in combat reports. They tested the P-40 at 75" MAP, too, but I do not claiming it generally flew at those numbers. If youa re going to take the highest numbers you can find and claim all of them were that good, the argument falls on its face all by itself.


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## Milosh (Jan 23, 2021)

*Lend-Lease aircraft supplied to the Red Air Force 1942-1944* 

*US aircraft *Total
Curtiss P-40 2,097
Bell P-39 Airacobra 4,746
Bell P-63 Kingcobra 2,400
P-47 Thunderbolt 195
B-25 Mitchell 862
Douglas A-20 Boston 2,908
*US total *13,208

*British aircraft *Total
Curtiss Tomahawks, Kittyhawks 270
Hawker Hurricane 2,952
Spitfire Mk V 143
Spitfire Mk IX 1,188
Handley Page Hampden 46
Armstong Albemarle 14
*British total *4,613
*OVERALL *17,821


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## GrauGeist (Jan 23, 2021)

The British gave the Soviet Union many of their Airacobras, too.


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## SaparotRob (Jan 23, 2021)

GrauGeist said:


> The British gave the Soviet Union many of their Airacobras, too.


.. and happily.


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## TheMadPenguin (Jan 23, 2021)

swampyankee said:


> All the helicopter installations used cooling fans.


Umm... you DO KNOW that "cooling fan" is what keeps the helicopter airborne, yes?

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## GrauGeist (Jan 23, 2021)

TheMadPenguin said:


> Umm... you DO KNOW that "cooling fan" is what keeps the helicopter airborne, yes?


Early Sikorsky's had their radial engines encased in the nose - plus on most helos, the prop-wash is minimal at the hub.

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## TheMadPenguin (Jan 23, 2021)

GrauGeist said:


> Early Sikorsky's had their radial engines encased in the nose - plus on most helos, the prop-wash is minimal at the hub.


There you go, spoiling the joke...

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## SaparotRob (Jan 23, 2021)

TheMadPenguin said:


> There you go, spoiling the joke...


I know, right?


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## Admiral Beez (Jan 23, 2021)

GrauGeist said:


> The British gave the Soviet Union many of their Airacobras, too.


The Soviets can have them, but I’d preferred that the British had kept their Canadian-made Valentines and Hurricanes. Those two should have gone to North Africa and/or Malaya.


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## pbehn (Jan 23, 2021)

Admiral Beez said:


> The Soviets can have them, but I’d preferred that the British had kept their Canadian-made Valentines and Hurricanes. Those two should have gone to North Africa and/or Malaya.


At what time? In the early days of the war between Germany and Russia it was a conflict that the allies couldn't afford to lose.

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## GregP (Jan 23, 2021)

So, what exactly is a Valentine? 

I mean other than for Valentine's Day.


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## Shortround6 (Jan 23, 2021)

a small, slow, not very well armed tank with thick armor, was more reliable than many British tanks though.


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## Admiral Beez (Jan 23, 2021)

GregP said:


> So, what exactly is a Valentine?


This is a Valentine, of the Canadian variety. It is these, and Canada’s Hurricanes that I want to ship to North Africa and/or Malaya instead of to Russia. 






As it was, IIRC many of both intended for the USSR ended up being lost at sea, something that would have spared any shipped to Malaya via Vancouver.


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## GrauGeist (Jan 23, 2021)

The Japanese were very proficient at sinking cargo ships, too...


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## GregP (Jan 24, 2021)

Out of nothing but curiosity, and not disputing what you say, why would you call it a Valentine instead of a Hurricane?


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## GrauGeist (Jan 24, 2021)

Aparently Canadian built Hurricane fighters and Valentine Tanks...


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## P-39 Expert (Jan 24, 2021)

GregP said:


> It didn't HAVE that climb rate uless they ran extra MAP. Use the POH climb rates for U.S. sevice airplanes abd service MAP levels. It sure isn't even 3,000 fpm in climb, especially at 44" MAP, and P-39s typically took off at about 8,000 lbs, not 7,500 lbs.
> 
> The statement was made that the P-39 shot down more enemy aircraft than any other American fighter in Soviet service. So, how many did it shoot down and what is the source for that statement. I have certainly seen the statement in print, have repeated it myself, but have also seen no victory figures with sources to back it up. So, its basically an unsupported statement.
> 
> Enough round words of greatness, what are the figures? I hope they imclude sorties, too. including action and non-action sorties.


You want figures, but the official Wright Field tests are somehow wrong. And there were two P-39N tests that verified those climb numbers, one at WEP and one without. No WEP available over the critical altitude anyway. POH climb rates are always lower than comparable tests, for every AAF plane. POH was a guide for the pilots, not the results of an official test.

Russian P-39 claims are available, just search.


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## P-39 Expert (Jan 24, 2021)

Shortround6 said:


> Yep and none of them used the procedure you outlined.


They all took off on internal, cruised out on external and came back on internal.


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## Shortround6 (Jan 24, 2021)

P-39 Expert said:


> They all took off on internal, cruised out on external and came back on internal.



Not quite what you said earlier, then it was.
1, warm up on external
2, taxi out on external.
3. take off on internal
4, switch to external in a minute 
5, then cruise out out external.
6. come back in internal
.
So if we ignore or change items 1, 2 and quite possibly 4 then your latest statement is correct.


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## Admiral Beez (Jan 24, 2021)

GrauGeist said:


> The Japanese were very proficient at sinking cargo ships, too...


If any go to Malaya it’s a prewar deployment.


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## GrauGeist (Jan 24, 2021)

Admiral Beez said:


> If any go to Malaya it’s a prewar deployment.


The Canadian Valentine was still pre-production by 1941


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## Admiral Beez (Jan 24, 2021)

GrauGeist said:


> The Canadian Valentine was still pre-production by 1941


If we can’t get any before hostilities begin they should go to North Africa. As for the Canadian-made Hurricanes, they could have been railed to Vancouver throughout 1940 and 41.


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## SaparotRob (Jan 24, 2021)

When you guys mention Valentine, are you talking about the tank or yet another airplane I never heard of?


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## buffnut453 (Jan 24, 2021)

It's a tank.

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## Milosh (Jan 24, 2021)

To develop its own tank forces, Canada had established tank production facilities. An order was placed in 1940 with Canadian Pacific and after modifications to the Valentine design to use local standards and materials, the production prototype was finished in 1941. Canadian production was mainly at CPR Angus Shops in Montreal and 1,420 were produced in Canada of 1,388 were sent to the Soviet-Union, with 2,394 exported from Britain. They formed the main Commonwealth export to the Soviet Union under lend-lease. The remaining 32 were retained for training. The use of local GMC Detroit Diesel engines in Canadian production was a success and the engine was adopted for British production. British and Canadian production totaled 8,275, making the Valentine the most produced British tank design of the war. Valentine tank - Wikipedia

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## Juha3 (Jan 24, 2021)

Shortround6 said:


> View attachment 609939
> 
> a small, slow, not very well armed tank with thick armor, was more reliable than many British tanks though.



The Valentine in the photo is one of the late versions with a long barrelled 57 mm (6 pdr) cannon, so it had better A/T capacity than a standard Sherman, late Churchills, Cromwells used in the ETO or T-34/76 and KV-1. Soviets even used them sometimes for Tiger hunting because it was small. fairly silent and had a good A/T capacity. Valentine was the only British tank that Soviets asked more and it was kept in production after British thought it was obsolescent only because of the Soviet demands.

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## SaparotRob (Jan 24, 2021)

As long as we’re off thread, Sherman “Firefly” rules.

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## GrauGeist (Jan 24, 2021)

SaparotRob said:


> As long as we’re off thread, Sherman “Firefly” rules.


Noway - StuG III for the win!

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## SaparotRob (Jan 24, 2021)

GrauGeist said:


> Noway - StuG III for the win!


Ah yes, the “StuG life”. 
Lotsa’ good stuff on YouTube about that.


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## Admiral Beez (Jan 24, 2021)

SaparotRob said:


> When you guys mention Valentine, are you talking about the tank or yet another airplane I never heard of?


Might be both. Here's a proposal by Raoul Hafner, to fit a rotor to the Valentine tank. The prototype was tested as the "Rotabuggy", by which time the concept was superseded by the Hamilcar transport glider.





Hafner "Rotabuggy" helicopter - development history, photos, technical data

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## GregP (Jan 24, 2021)

P-39 Expert,

The test for the P-39N-1 was conducted at 7,272 lbs with ammunition in it. A stock P-39N-1 came in at 7,468 lbs. with ammunition in it. The only things that could be removed were amror, and it puts the P-39N right about the test weight. The climb test was at 50.5" MAP or full throttle, whichever is available. The U.S didn't fly them without armor or at that boost level in service, at least for a good chunk of the P-39's operational career. They flew them by the POH and squadron standard operating procedures, which weren't especially lenient about boost.

Get real. Nobody ever gets the absolute best performance ever recorded for an airplane in normal use, especially after a few months outside in the environment. There is nothing wrong with the Wright field tests. Just your determinination to use the lightweight WER Wright Field test results as normal for the P-39N, which they weren't. 

But, I expect you'll stick to your guns even in the face of testimony from people who flew the P-39 that it was a dog in general. I bet in you world, stock muscle cars always run quarter miles in the quickest time ever recorded for a stock vehicle by a professional driver, too.

Not in the real world.

I had a good friend in high school who became a professional golfer. He told me once that par was the score an average professional should achieve on an average day, and that golf was the only endeavor where the average amateur participant somehow expected to be able to shoot as well as the average professional. Apparently, it isn't the ONLY endeavor where that happens.

Cheers.

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## pbehn (Jan 24, 2021)

GregP said:


> Get real. Nobody ever gets the absolute best performance ever recorded for an airplane in normal use, especially after a few months outside in the environment. There is nothing wrong with the Wright field tests. Just your determinination to use the lightweight WER Wright Field test results as normal for the P-39N, which they weren't.
> .


Absolute best performance isn't top speed either, top speed is just one measure. The Spitfire Mk II was slightly slower than the MkI because that's what the RAF wanted, or rather they would sacrifice a few MPH on top speed to have an all around better aircraft.


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## XBe02Drvr (Jan 24, 2021)

Hey folks, I sense that many here are suffering from Airacobra fatigue. I know I am. How about we enter into a gentlemen's agreement to refrain from continuing to feed this beast which has devoured so many threads on this forum and diverted us from more meaningful topics? There are plenty other aircraft out there that could be improved more profitably than the P39.
What say ye?

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## nuuumannn (Jan 24, 2021)

SaparotRob said:


> As long as we’re off thread, Sherman “Firefly” rules.



How about the Panzerkampfwagen (Grumman F-11) "Tiger"?



Admiral Beez said:


> The prototype was tested as the "Rotabuggy"



Hafner was an imaginative fella... A couple more of the Rotabuggy concept in practise...





0207 Museum of Army Flying Rotor Jeep




0207 Museum of Army Flying Rotachute

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## Admiral Beez (Jan 25, 2021)

Admiral Beez said:


> How about early development and adoption of three blade, variable pitch props for the Spitfire and Hurricane? This may get us to an earlier Sea Hurricane, for starters.





P-39 Expert said:


> Expand above.


We discussed in another thread VP props to get the Sea Hurricane into earlier service.

Earlier/better/more Sea Hurricane: pros cons


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## XBe02Drvr (Jan 25, 2021)

Admiral Beez said:


> We discussed in another thread VP props to get the Sea Hurricane into earlier service.
> 
> Earlier/better/more Sea Hurricane: pros cons


If you're going to put all the effort and weight into converting to a variable pitch propeller it's silly to not replace the actuating oil selector valve with a governor and have a full constant speed propeller system.
In practice, a variable pitch prop is essentially a two position fixed pitch prop. You can select back and forth between a "climb" prop and a "cruise" prop, but anything in between requires too much distraction of the pilot from flying and fighting, and he/she still has no protection against overreving or over-squaring (lugging) the engine.
For the ten to fifteen pound penalty of a governor, your variable pitch two position propeller can become constant speed and will hold whatever RPM you set it at, regardless of aerodynamic loads and throttle setting. Frees up the pilot for flying and fighting and maintaining situational awareness.
There's no fancy high technology or exotic production techniques in a hydraulic prop governor, which leaves attitudes and inertia as the primary reasons why it was so late in coming. Once you've flown one, it's a no-brainer.
Cheers,
Wes

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## Admiral Beez (Jan 25, 2021)

XBe02Drvr said:


> For the ten to fifteen pound penalty of a governor, your variable pitch two position propeller can become constant speed and will hold whatever RPM you set it at, regardless of aerodynamic loads and throttle setting.


Keeping the early Hurricane's lower power Merlin, would this get a Sea Hurricane, especially one with the added weight of folding wings off a carrier's 500-600ft flight deck with 25-40 knots WOD? AIUI, the original fixed, two blade Hurricanes with the early Merlin would have been challenged to get off the deck, especially with the folding mechanism.


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## ThomasP (Jan 25, 2021)

Yes.

Somewhere, on the internet . . . there are tests for the Hurricane Mk I when switched from the Watts 2-blade wood prop to the (Rotol? DH?) CS prop. While the top speed dropped a few mph, the TO run decreased significantly and the climb improved a bit.

edit: Found one of the tests. Hurricane Mk I at ~6300 lb TOGW had a TO roll (zero wind) decreased from 1110 ft (Watts 2-blade wood prop) , to 840 ft (DH 3-blade 2-pitch), to 720 ft (Rotol CS prop).

edit again: The TO run for the Watts was 1110 ft, it was the DH 2-pitch that had a TO run of 840 ft, so the difference was even greater


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## Milosh (Jan 25, 2021)

Admiral Beez said:


> Keeping the early Hurricane's lower power Merlin, would this get a Sea Hurricane, especially one with the added weight of folding wings off a carrier's 500-600ft flight deck with 25-40 knots WOD? AIUI, the original fixed, two blade Hurricanes with the early Merlin would have been challenged to get off the deck, especially with the folding mechanism.


Did the See Hurricane ever have folding wings?


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## ThomasP (Jan 25, 2021)

Unfortunately, no.


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## Admiral Beez (Jan 25, 2021)

Milosh said:


> Did the See Hurricane ever have folding wings?


No, but it was probably the easiest of all the RAF's fighters to modify for them. Just need to install a hinge where the wing snaps on. This is why I want to improve the Hurricane, so that we can gain the ability to operate from carriers with narrow 22-25 ft wide lifts, like Ark Royal and Illustrious, but in 1939, not 1942 when folding Martlets, Fulmars and (eventually) Seafires canceled the need for a folding Sea Hurricane.

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## ThomasP (Jan 25, 2021)

Edited my post#1,168 above for TO distances.


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## Admiral Beez (Jan 25, 2021)

While we're at it.... I want the Sabre engine made reliable earlier, so I can have this....

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## XBe02Drvr (Jan 25, 2021)

Admiral Beez said:


> Keeping the early Hurricane's lower power Merlin, would this get a Sea Hurricane, especially one with the added weight of folding wings off a carrier's 500-600ft flight deck with 25-40 knots WOD? AIUI, the original fixed, two blade Hurricanes with the early Merlin would have been challenged to get off the deck, especially with the folding mechanism.


More blades will usually convert the same horsepower into more thrust at lower speeds, while fewer blades are usually more efficient at the top end. A fixed pitch "climb" prop (or a VP prop at max fine position) is generally set for just a little shy of its optimum pitch in an attempt to give the engine a little protection from over revving as the aircraft accelerates. The same thing occurs in reverse at the top end, also for over rev reasons.
A constant speed prop can have its pitch stops expanded a bit in both directions, as long as the governor's travel is limited to keep revs out of the red, thus allowing for a tad more efficiency at both ends of the spectrum.
Unfortunately, AFAIK, no one's yet come up with a variable blade count propeller to extract that last percentage point at the high end!

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## Glider (Jan 25, 2021)

Admiral Beez said:


> While we're at it.... I want the Sabre engine made reliable earlier, so I can have this....
> 
> View attachment 610196


Now that would have been more than handy


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## pbehn (Jan 25, 2021)

Admiral Beez said:


> While we're at it.... I want the Sabre engine made reliable earlier, so I can have this....
> 
> View attachment 610196


The Sabre was never reliable, it became less than chronically unreliable after many years.


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## nuuumannn (Jan 25, 2021)

Admiral Beez said:


> While we're at it.... I want the Sabre engine made reliable earlier, so I can have this....



And to think that was the back-up to the Firebrand entering service as the Fleet Air Arm's fighter du jour...


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## nuuumannn (Jan 25, 2021)

XBe02Drvr said:


> If you're going to put all the effort and weight into converting to a variable pitch propeller it's silly to not replace the actuating oil selector valve with a governor and have a full constant speed propeller system.



Yup, that Woodward C/S governor was readily available too. If only it could be built under licence, like, say, Hamilton Standard props by de Havilland... Wait a minute...


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## XBe02Drvr (Jan 25, 2021)

nuuumannn said:


> Yup, that Woodward C/S governor was readily available too. If only it could be built under licence, like, say, Hamilton Standard props by de Havilland... Wait a minute...


NIH Syndrome? "Bloody colonials, going gadget-happy on us again! And make us pay through the nose for the privilege! That's one gadget we can do without."


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## Shortround6 (Jan 25, 2021)

XBe02Drvr said:


> NIH Syndrome? "Bloody colonials, going gadget-happy on us again! And make us pay through the nose for the privilege! That's one gadget we can do without."


 It's bad enough we have to fly monoplanes and have wheels with brakes, now they want us to have those heavy, expensive bloody variable pitch propellers too. 

I Keep saying. 20 different airlines around the world were using constant speed _*fully feathering*_ propellers in *1938*. It was not a military secret or particularly expensive if airlines thought it was a good idea, profit and loss and all that.

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## XBe02Drvr (Jan 26, 2021)

Shortround6 said:


> It's bad enough we have to fly monoplanes and have wheels with brakes, now they want us to have those heavy, expensive bloody variable pitch propellers too.


Or even worse (horror of horrors!), those bloody CONSTANT SPEED propellers! Sheer bloody gadgetry!

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## nuuumannn (Jan 26, 2021)

XBe02Drvr said:


> Or even worse (horror of horrors!), those bloody CONSTANT SPEED propellers! Sheer bloody gadgetry!



And cooping a flier up INSIDE the aeroplane??? And what's wrong with precision flying VIC formations into battle? It's good discipline!

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## Admiral Beez (Jan 28, 2021)

I like the look of the Curtiss A-18 Shrike. Surely we can improve this design to make it a competitor in WW2. Swap in a pair of Allison inline engines?

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## tomo pauk (Jan 28, 2021)

Already the 1000+ HP Cyclones or Twin Wasps are an improvement.

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## Admiral Beez (Jan 28, 2021)

tomo pauk said:


> Already the 1000+ HP Cyclones or Twin Wasps are an improvement.


I agree. Improve the canopy and you could have a USAAF Mosquito, or at least a Kawasaki Ki-45 or even a Gekko.




.

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## Shortround6 (Jan 28, 2021)

Admiral Beez said:


> I like the look of the Curtiss A-18 Shrike. Surely we can improve this design to make it a competitor in WW2. Swap in a pair of Allison inline engines?
> 
> View attachment 610512




Been looked at before. 
It has a 530 sq ft wing that is fabric covered from the main spar aft. 

Basically an American Blenheim with a skinny fuselage. 
Throw it out and start over.


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## Glider (Jan 28, 2021)

Shortround6 said:


> It's bad enough we have to fly monoplanes and have wheels with brakes, now they want us to have those heavy, expensive bloody variable pitch propellers too.
> 
> .


You can always try gliding, no big noisy thing in front that causes panic if it stops and all goes quiet.

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## XBe02Drvr (Jan 28, 2021)

Glider said:


> You can always try gliding, no big noisy thing in front that causes panic if it stops and all goes quiet.


But there's no fan to keep the pilot from sweating under his plexiglas bubble on a sunny day!* You'd have a pilot strike on your hands for sure.

*That WWII Schweizer TG2 I got a couple rides in as a teen was an oven with wings.

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## SaparotRob (Jan 28, 2021)

I went up in a sailplane a couple of times years ago. A Schweitzer, I believe. Most fun I had with my clothes on. I had about 2 minutes of stick time. So Wes, if I happen to be passengering with you and we lose both engines, I can help you out.

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## SaparotRob (Jan 28, 2021)

I said that to a pilot on a flight I took long ago. My first aviation laugh.

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## Glider (Jan 28, 2021)

XBe02Drvr said:


> But there's no fan to keep the pilot from sweating under his plexiglas bubble on a sunny day!* You'd have a pilot strike on your hands for sure.
> 
> *That WWII Schweizer TG2 I got a couple rides in as a teen was an oven with wings.



True, but can you think of a better way to get an almost instant tan!!

PS there are air vents to help


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## swampyankee (Jan 28, 2021)

XBe02Drvr said:


> But there's no fan to keep the pilot from sweating under his plexiglas bubble on a sunny day!* You'd have a pilot strike on your hands for sure.
> 
> *That WWII Schweizer TG2 I got a couple rides in as a teen was an oven with wings.



Plexiglass bubble?

How gauche. Open cockpit, lads.

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## XBe02Drvr (Jan 28, 2021)

SaparotRob said:


> I went up in a sailplane a couple of times years ago. A Schweitzer, I believe. Most fun I had with my clothes on. I had about 2 minutes of stick time. So Wes, if I happen to be passengering with you and we lose both engines, I can help you out.


I used to be a glider flight instructor, so if that ever happens to us, I'm PF, you can be PNF. Make sure your emergency checklist is handy and your memory items are reflexive. Sh!t happens quick.


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## SaparotRob (Jan 28, 2021)

XBe02Drvr said:


> I used to be a glider flight instructor, so if that ever happens to us, I'm PF, you can be PNF. Make sure your emergency checklist is handy and your memory items are reflexive. Sh!t happens quick.


We’re dead.

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## XBe02Drvr (Jan 28, 2021)

Glider said:


> PS there are air vents to help


When best glide speed is only 38 MPH (a real floater) and both vents are in the front cockpit, it doesn't do much for you back in the hell hole. Back in WII they probably figured the "old pro" instructors in back could keep their cool unaided, while the poor nugget up front needed all the help he could get.

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## XBe02Drvr (Jan 28, 2021)

swampyankee said:


> Plexiglass bubble?
> 
> How gauche. Open cockpit, lads.


The TG2 (SGS2-8)'s immediate predecessor, the Schweizer SGS1-7, WAS open cockpit. My favorite was the 2-32, "the B52 of gliders".


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## SaparotRob (Jan 28, 2021)

How long ago was that sailplane introduced? Sure looks and seems like the one on my second flight. I went up with my then girlfriend and let me tell you, it’s a great date!


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## Glider (Jan 28, 2021)

XBe02Drvr said:


> When best glide speed is only 38 MPH (a real floater) and both vents are in the front cockpit, it doesn't do much for you back in the hell hole. Back in WII they probably figured the "old pro" instructors in back could keep their cool unaided, while the poor nugget up front needed all the help he could get.


That is slow. I was more used to instructing on the K13 which was no rocket ship.


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## nuuumannn (Jan 28, 2021)

swampyankee said:


> How gauche. Open cockpit, lads.



Amateurs...




MoF 46




Musee de l&#x27;Air 161

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## Glider (Jan 28, 2021)

At least they won't complain about getting too hot.

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## XBe02Drvr (Jan 28, 2021)

SaparotRob said:


> How long ago was that sailplane introduced? Sure looks and seems like the one on my second flight. I went up with my then girlfriend and let me tell you, it’s a great date!


The 2-32 was first available in 1964, and all 87 were produced in less than a decade. If you both went on the same flight, almost certainly it was a 2-32. Most glider operations used it as a cash cow, two rides for one flight, but it required a robust tug: Bird dog or Pawnee; Super Cubs and Citabrias were pretty marginal for the job. Our club made theirs off limits for member's recreational flying. Only Commercial CFIs could get checked out in "the bomber" and then only to fly commercial rides. When did you fly? I might have been your pilot.
Babs Nutt, the examiner who gave me my Glider Commercial and CFI, still (posthumously now) holds the feminine absolute altitude record (35,000+ feet) for 2-seat gliders, which she set in a 2-32 in the 1970s. She was a great pilot, a great teacher, and even owned her own airport. Read Burton Bernstein's book, _Plane Crazy_ For an account of Babs and her airport.

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## SaparotRob (Jan 28, 2021)

This had to be in the ‘80’s. It was with Soaring Adventures at Gabreski Airport, Long Island, New York. I still have the refrigerator magnet.

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## SaparotRob (Jan 28, 2021)

I’m changing the date to probably early ‘90’s.


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## XBe02Drvr (Jan 28, 2021)

SaparotRob said:


> This had to be in the ‘80’s. It was with Soaring Adventures at Gabreski Airport, Long Island, New York. I still have the refrigerator magnet.
> View attachment 610556


That's a 2-32, alright. Crowded airspace to be soaring in back in the the day, with Grumman flight test right nearby and east JFK arrivals and departures and with NY ANG based there. We had a lot less traffic issues up in VT.


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## SaparotRob (Jan 28, 2021)

By way of context, Grumman had lost the F-14D contract a couple of years earlier. Would Grumman flight testing have been reduced?


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## XBe02Drvr (Jan 29, 2021)

SaparotRob said:


> By way of context, Grumman had lost the F-14D contract a couple of years earlier. Would Grumman flight testing have been reduced?


Grumman was still at it; they did electronic warfare conversions on the F111 and F18, and were upgrading the E2C and EP3C.

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## XBe02Drvr (Jan 29, 2021)

SaparotRob said:


> This had to be in the ‘80’s. It was with Soaring Adventures at Gabreski Airport, Long Island, New York.


I used to pass through that area on BOS-JFK and PVD-JFK flights. If you went IFR, ATC would send you "the great circle route", up to 10,000 feet, out the Victor Airway towards ALB, then trickle you down in a series of steps south across western CT, over Bridgeport, across the sound, and into JFK, about doubling the mileage. Weather permitting, we would go VFR down Narragansett Bay and Long Island Sound at 2,500 feet. Passengers loved this and always asked for it. Our fuel purchasing agent loved it too.
The fly in the ointment was the fog bank that could form rapidly over Long Island and the Sound after a wind change, leaving us orbiting east of Montauk begging ATC for a pop up IFR clearance into Kennedy. Said wind change would, of course dictate a runway change at JFK, and the redirecting of the streams of inbound traffic and the departures taxiing to their initially assigned runways. A regular chinese fire drill if it caught the weather guessers by surprise.
When we got our IFR it would be up to 3,000, direct Calverton, (Grumman Plant), Calverton 195° radial to some obscure waypoint 25 miles out to sea, then hold. Souls on board? Fuel remaining? They would give us an Expect Further Clearence time 25 minutes shy of our fuel exhaustion time, and seemingly forget about us. We quickly learned to lie about our fuel remaining and pad it by 30 minutes.
All in a day's work.

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## Koopernic (Jan 29, 2021)

Admiral Beez said:


> I like the look of the Curtiss A-18 Shrike. Surely we can improve this design to make it a competitor in WW2. Swap in a pair of Allison inline engines?
> 
> View attachment 610512


Instead of 9 cylinder CW R-1820-47 of 850hp use a 12 cylinder PW R-1830-21 of 1200 hp.

40% extra power should give about 13% extra speed should get speed from 247mph to 280mph. There would be some speed gain from the lower frontal area radial.


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## Shortround6 (Jan 29, 2021)

Koopernic said:


> Instead of 9 cylinder CW R-1820-47 of 850hp use a 12 cylinder PW R-1830-21 of 1200 hp.
> 
> 40% extra power should give about 13% extra speed should get speed from 247mph to 280mph. There would be some speed gain from the lower frontal area radial.



AND that pretty much explains WHY it wasn't done.

Martin 167 (AKA Maryland)




304mph at 13,000ft using 1050hp R-1830s.

Douglas DB-7




304mph at 5,000ft using 1100hp R-1830 engines.

North American NA-40




A mere 268mph at 5000ft using 1100hp R-1830 engines.

Stearman XA-21




257mph using P&W R-2180s.

All four planes were flying in 1938 for a design competition to replace the A-17 single engine attack plane and the A-18 Shrike. 
Curtiss did not bother to enter an updated version in the competition.
The Douglas and the Sterman both crashed before the actual flying evaluation but the army later ordered the DB-7 which evolved into the A-20, France ordered the Martin 167 design and North American reworked the NA-40 into the B-25. 

BTW the R-1820 engines in the A-18 weighed 1178lbs each.
1200hp P&W R-1830s don't show up until 1940/41 and the lightest versions with single speed superchargers weigh around 1420-1460lbs depending on propeller reduction gear and other details.

Despite the smaller diameter radials there may have been too much detail drag on the A-18, or too much that needed changing besides the engines.

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## XBe02Drvr (Jan 29, 2021)

Koopernic said:


> Instead of 9 cylinder CW R-1820-47 of 850hp use a 12 cylinder PW R-1830-21 of 1200 hp.


Actually, the 1830 is a 14 cylinder engine. Each row in a radial has to have an odd number of cylinders. Try to work out a firing order for an even number and you'll see why. With radials cooling drag is generally proportional to heat dissipation requirements, irrespective of frontal diameter. The extra internal baffling to keep the second row cool largely cancels the gain from smaller diameter. Compare performance of C47/DC3s with equivalent horsepower 1820s and 1830s. No significant difference.



Shortround6 said:


> Despite the smaller diameter radials there may have been too much detail drag on the A-18, or too much that needed changing besides the engines.


In a nutshell.

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## Shortround6 (Jan 29, 2021)

I would also note that this type aircraft could make 248mph at 8000ft on just about the same engines as the A-18 used. 





If an airliner with a crew of 3 and 10-11 passengers can go as fast as your light bomber/attack aircraft using the same engines then either the published figures are off or there is something wrong with the design of the attack aircraft or both.

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## Admiral Beez (Jan 29, 2021)

Have Rolls-Royce skip the Exe and Vulture, and Eagle programs and focused entirely on the Merlin and Griffon.

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## tomo pauk (Jan 29, 2021)

Admiral Beez said:


> Have Rolls-Royce skipped the Exe and Vulture, and Eagle programs and focused entirely on the Merlin and Griffon.



This, very much. Skip the Peregrine, too.


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## SaparotRob (Jan 29, 2021)

XBe02Drvr said:


> I used to pass through that area on BOS-JFK and PVD-JFK flights. If you went IFR, ATC would send you "the great circle route", up to 10,000 feet, out the Victor Airway towards ALB, then trickle you down in a series of steps south across western CT, over Bridgeport, across the sound, and into JFK, about doubling the mileage. Weather permitting, we would go VFR down Narragansett Bay and Long Island Sound at 2,500 feet. Passengers loved this and always asked for it. Our fuel purchasing agent loved it too.
> The fly in the ointment was the fog bank that could form rapidly over Long Island and the Sound after a wind change, leaving us orbiting east of Montauk begging ATC for a pop up IFR clearance into Kennedy. Said wind change would, of course dictate a runway change at JFK, and the redirecting of the streams of inbound traffic and the departures taxiing to their initially assigned runways. A regular chinese fire drill if it caught the weather guessers by surprise.
> When we got our IFR it would be up to 3,000, direct Calverton, (Grumman Plant), Calverton 195° radial to some obscure waypoint 25 miles out to sea, then hold. Souls on board? Fuel remaining? They would give us an Expect Further Clearence time 25 minutes shy of our fuel exhaustion time, and seemingly forget about us. We quickly learned to lie about our fuel remaining and pad it by 30 minutes.
> All in a day's work.


Don’t forget the Grand Tour of all the runways and hangars at JFK as we taxi to some elusive gate.


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## SaparotRob (Jan 29, 2021)

I was the only baggage on board that LOVED it.


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## XBe02Drvr (Jan 29, 2021)

SaparotRob said:


> Don’t forget the Grand Tour of all the runways and hangars at JFK as we taxi to some elusive gate.


"Ground, Metro Air three four one seven's clear of two two left at Echo Echo for gate six five."
"Metro thirty four seventeen..huh...standby...uh, you can't get to that gate from where you are due to construction on Charlie Echo. Make a one eighty and stand by. If we ever get a break in traffic we'll backtaxi you on the runway to Golf. Sorry bout that."

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## XBe02Drvr (Jan 29, 2021)

Shortround6 said:


> I would also note that this type aircraft could make 248mph at 8000ft on just about the same engines as the A-18 used.


Then there's the nugget pilot in an old OTU P39 off the California coast who saw a sleek four engine plane with a triple tail cruising through his practice area at a high rate of speed. He dove down, formed up on its left wing, and discovered he needed full throttle just to stay with it. The Lockheed test pilot noticed him, waved, then pulled smartly ahead and vanished in the haze.

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## SaparotRob (Jan 29, 2021)

XBe02Drvr said:


> Then there's the nugget pilot in an old OTU P39 off the California coast who saw a sleek four engine plane with a triple tail cruising through his practice area at a high rate of speed. He dove down, formed up on its left wing, and discovered he needed full throttle just to stay with it. The Lockheed test pilot noticed him, waved, then pulled smartly ahead and vanished in the haze.


True or not, I love those stories.

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## wuzak (Jan 29, 2021)

Admiral Beez said:


> Have Rolls-Royce skip the Exe and Vulture, and Eagle programs and focused entirely on the Merlin and Griffon.



That pretty much happened after the BoB.

It also depends on when you are talking about. If you are saying that in mid to late 1937 then there is no Griffon on which to concentrate - paper or otherwise.


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## Admiral Beez (Jan 29, 2021)

wuzak said:


> That pretty much happened after the BoB.
> 
> It also depends on when you are talking about. If you are saying that in mid to late 1937 then there is no Griffon on which to concentrate - paper or otherwise.


Developmentally can‘t RR get to the Griffon through the Merlin?


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## GrauGeist (Jan 29, 2021)

I believe the Griffon was a clean-sheet design.


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## Reluctant Poster (Jan 31, 2021)

nuuumannn said:


> The Stirling (and Halifax) have always appeared to me to be over-engineered the more I learn about them and a lot of that, particularly in the Stirling's case comes from Air Ministry interference and attempting to work within the specifics of the written requirements and specs. Short Brothers had experience with large multi engined aircraft (as did Handley page for that matter), yet the Stirling, a massive undertaking at the time fell short of the performance criteria of B.12/36 for numerous reasons and came with built-in obsolescence that could not be worked around without major redesign.
> 
> What it does illustrate (along with the Halifax) is that it wasn't easy to put into production large four-engined aircraft built to mid 30s specifications and anticipating whether or not they would be viable going forward. That the Manchester was Avro's very first attempt at a big (ish) all-metal aircraft is impressive (Avro had built Blenheims under licence as their first all-metal type in its workshops) and resulted in a noble but flawed effort, but essentially once the aerodynamic (and equipment) issues were worked out was a very sound design free of the performance constraints of the Stirling and the aerodynamic and overly complicated problems the Halifax suffered. Of course, the Manchester benefitted from the torpedo requirement in P.13/36, giving it that impressively large unobstructed bomb bay, as well as its inherent strength as a result of the catapulting requirement.



I think massive is an appropriate adjective for anything to do with the Stirling. 
I think the blame for the Stirling rests almost entirely with the Shorts design team. The Air Ministry didn't insist that the Stirling have such a deep fuselage, in fact they were trying to limit the size. The Stirling fuselage was far deeper than is rival the Supermarine 317 ordered to the same specification. The Air Ministry didn't require the fuselage to be far longer than its rivals. The Air Ministry didn't insist on the largest, most complex undercarriage seen up to that time.
On the other hand the majority of credit for the Lancaster's large unobstructed bomb bay should go to Avro. The Halifax was built to the same spec but it couldnt even close its doors when carrying a cookie.

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## nuuumannn (Feb 1, 2021)

Agree with what you have to say, Reluctant poster.



Reluctant Poster said:


> The Air Ministry didn't insist on the largest, most complex undercarriage seen up to that time.



That was most definitely Short Bros since the wing incidence was found to be shallower than desired in the S.31 small scale aircraft, but the incidence on the Stirling couldn't have been altered at such a time, as development had already progressed on the prototype, so the undercarriage was altered to increase the wing's incidence angle. That the Air Ministry approved the Stirling to B.12/36 was on it however, but little did it know how convoluted the Stirling's development would become as a result of the original specification.



Reluctant Poster said:


> On the other hand the majority of credit for the Lancaster's large unobstructed bomb bay should go to Avro.



Yes and no. P.13/36 did stipulate the carriage of two 18 inch torpedoes side by side. It's worth remembering that the HP.56, which was the original entry to P.13/36 and the HP.57 were totally different designs and the latter, which was the Halifax was essentially an entirely new design. The Manchester echoed the original requirement's stipulations more closely than how the Halifax evolved, as the torpedo carrying and catapult requirement had been cancelled before the Halifax prototype had been finished, and the Manchester's design was altered to do away with the catapult requirement, which caused delays, although the big bomb bay remained.


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## Thumpalumpacus (Feb 9, 2021)

BiffF15 said:


> But at least it was loud, and the A/C sucked...
> 
> Cheers,
> Biff



We had a flight of six at my base, right in front of the fire station where I worked -- maybe 100 yards. They sounded like Black & Decker drills pulling 140 dB, and could wake us up in our sound-proofed bunkrooms.

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## Thumpalumpacus (Feb 9, 2021)

GregP said:


> The statement was made that the P-39 shot down more enemy aircraft than any other American fighter in Soviet service. So, how many did it shoot down and what is the source for that statement. I have certainly seen the statement in print, have repeated it myself, but have also seen no victory figures with sources to back it up. So, its basically an unsupported statement.
> 
> Enough round words of greatness, what are the figures? I hope they imclude sorties, too. including action and non-action sorties.



For that statement to have any meaning, we'd need to know 1) which other American fighters saw significant Soviet service, and in what numbers, and 2) total sorties. A fighter's efficiency isn't measured by kills, it's measured by kills per sortie, and/or kills per combat loss.

Put another way: I'd bet the -39 suffered the highest losses of any American fighter flying for the VVS. That too is simply a function of raw numbers, rather than any statement of quality or deficiency.

It looks like the P-39 doubled the numbers in Soviet use over the next American fighter, the P-40. Not sure about the kill/loss ratios between the two types under Soviet use. But I'd expect the P-39 to both have the most kills and the most losses, simply because they were more prevalent.

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## wuzak (Feb 10, 2021)

I have some suggestions for the P-39, with a couple of variations.


Lengthen main landing gear.
Move pilot close to the nose (now the nose armour is pilot armour).
Remove doors and replace with sliding canopy.
Remove guns from nose (no longer any space). Replace with a pair of 37mm M4 cannons (because they fire flat to 400 yards!) mounted on the sides, with the ammo bay behind the new pilot position. With the new placement longer barrels may be able to be fitted to the M4, enabling higher muzzle velocity. Add 2 or 4 M2 0.50 cals on the sides of the fuselage, using same ammo bay. Alternatively, ditch the M4s and replace with 4 x 20mm or 6 x 0.50" firing along the sides of the fuselage.
Provide extra fuel tank between the engine and ammo bay.
Use lower altitude V-1710 to turn P-39 into ground-pounder. Or find some way to fit a Merlin, or fit a Merlin supercharger to the V-170 for normal pursuit work.
Add nitrous oxide bottle for performance boost at altitude.
No wing guns, internal or suspended.

Variation A: Move prop to tail to become pusher aircraft. Replace conventional tail with one arranged like a Y - one fin down and two angled fins above. Could put a tail wheel in lower fin and remove nose gear.

Variation B: Not having enough variations of the V-1710 was always a problem for Allison, so have then design a remote gearbox and driveshaft assembly that takes the drive to a propeller on each wing, with a small nacelle. Drive shafts should, ideally, not interfere with wing tankage.


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## GrauGeist (Feb 10, 2021)

wuzak said:


> I have some suggestions for the P-39, with a couple of variations.
> 
> 
> Lengthen main landing gear.
> ...


Ok...so then something like this?

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## Zipper730 (Feb 10, 2021)

GrauGeist said:


> Ok...so then something like this?
> 
> View attachment 612183


What kind of plane is that?

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## GrauGeist (Feb 10, 2021)

Zipper730 said:


> What kind of plane is that?


Yokosuka R2Y1 of the IJN.

Messerschmitt had a nearly identical project, the Me509, though it did not progress nearly as far as the R2Y1.


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## BiffF15 (Feb 10, 2021)

wuzak said:


> I have some suggestions for the P-39, with a couple of variations.
> 
> 
> Lengthen main landing gear.
> ...



Or Variation C: Buy... More... Merlin... Mustangs...

Cheers,
Biff
😉

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## wuzak (Feb 11, 2021)

BiffF15 said:


> Or Variation C: Buy... More... Merlin... Mustangs...
> 
> Cheers,
> Biff
> 😉



Actually, variation C: have Bell build the P-51B or D.

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## P-39 Expert (Feb 11, 2021)

wuzak said:


> I have some suggestions for the P-39, with a couple of variations.
> 
> 
> Lengthen main landing gear.
> ...


You need a whole new plane. I always liked the idea of the pusher with a simpler radial with a cooling fan pulling air through the engine. Something like an XP-56 but more stable.


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## wuzak (Feb 11, 2021)

P-39 Expert said:


> You need a whole new plane. I always liked the idea of the pusher with a simpler radial with a cooling fan pulling air through the engine. Something like an XP-56 but more stable.



I think the P-39 is uniquely set up to convert to a pusher!

But I like your thinking - keep the IFF and build a completely new aircraft.


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## wuzak (Feb 11, 2021)

BiffF15 said:


> Or Variation C: Buy... More... Merlin... Mustangs...
> 
> Cheers,
> Biff
> 😉



The only other thing to say about that is that my suggested mods could make the P-39 into an effective low altitude ground attack aircraft.


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## Shortround6 (Feb 11, 2021)

except the 37mm guns would have to be pushed Wwaaaaaaayyyyyy out.

I don't believe they could be synchronized and 37mm projectile (even without explosive) meeting propeller blade makes for a really bad day. 

Time for the pusher prop?

Just be careful or the customer may demand something like this.


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## XBe02Drvr (Feb 12, 2021)

Shortround6 said:


> Just be careful or the customer may demand something like this.
> View attachment 612280


Fantastique! Ze WussAir!


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## P-39 Expert (Feb 12, 2021)

Shortround6 said:


> except the 37mm guns would have to be pushed Wwaaaaaaayyyyyy out.
> 
> I don't believe they could be synchronized and 37mm projectile (even without explosive) meeting propeller blade makes for a really bad day.
> 
> ...


Correct on the 37mm not synchronizable, and they had to be in the nose. Out on the wings the slow rate of fire would have had them spraying shells all over the sky unless they somehow fired at the same exact instant (doubtful).

What is that second open cockpit up on top in the photo? 

I think the pusher was the wave of the future in WWII, but then the jet engine came along and they all became pushers.


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## tyrodtom (Feb 12, 2021)

P-39 Expert said:


> Correct on the 37mm not synchronizable, and they had to be in the nose. Out on the wings the slow rate of fire would have had them spraying shells all over the sky unless they somehow fired at the same exact instant (doubtful).
> 
> What is that second open cockpit up on top in the photo?
> 
> I think the pusher was the wave of the future in WWII, but then the jet engine came along and they all became pushers.



Wave of the future during WW2 , the pusher ???
Can you think of a single successful pusher design from WW2 ?
The Saab 21 hardly qualifies , it didn't become operational till after WW2 was over.


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## P-39 Expert (Feb 12, 2021)

tyrodtom said:


> Wave of the future during WW2 , the pusher ???
> Can you think of a single successful pusher design from WW2 ?
> The Saab 21 hardly qualifies , it didn't become operational till after WW2 was over.


Japanese Shinden? Very late in the war if it made it at all.


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## tyrodtom (Feb 12, 2021)

The Shinden had one or two successful flights.
Is that your definition of a successful aircraft ?
Well, 3 flights in early August 45, for a grand total of 45 minutes of flight time.


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## P-39 Expert (Feb 12, 2021)

tyrodtom said:


> The Shinden had one or two successful flights.
> Is that your definition of a successful aircraft ?
> Well, 3 flights in early August 45, for a grand total of 45 minutes of flight time.


Only one I could think of.

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## GrauGeist (Feb 13, 2021)

Does the Do335 with it's front engine shut off count? 

Plenty of pusher designs:
Curtiss XP-55
Ambrosini SS.4
Miles M.35
Vulture XP-54
Kayaba Ku-4 (which looked a great deal like the Handley-Page HP.75)
Northrop XP-56

And an interesting sidenote:
Bell had two pusher designs in the works, the XP-52 and XP-59 (not the XP-59A) but the projects were shelved.


And yes, the J7W as already mentioned.

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## tyrodtom (Feb 13, 2021)

GrauGeist said:


> Does the Do335 with it's front engine shut off count?
> 
> Plenty of pusher designs:
> Curtiss XP-55
> ...




There's several pusher designs out there during the WW2 era, but how many made it past the prototype/ research phase into production ?
Only the Saab 21, and it barely qualifies as being WW2 era.


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## GrauGeist (Feb 13, 2021)

tyrodtom said:


> There's several pusher designs out there during the WW2 era, but how many made it past the prototype/ research phase into production ?
> Only the Saab 21, and it barely qualifies as being WW2 era.


Which is why I joked about the Do335 - plenty of fighter designs but nothing really came of any of them.
The J7W had several issues that had to be worked out, like overheating, torque roll and shaft vibration.
*if* the Japanese had enough time, than perhaps it might have had a chance, but to be honest, I doubt it. Like many other nations, they had jets in the works and the efforts to address the Shiden's problems might not have been worth it.


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## P-39 Expert (Feb 14, 2021)

GrauGeist said:


> Which is why I joked about the Do335 - plenty of fighter designs but nothing really came of any of them.
> The J7W had several issues that had to be worked out, like overheating, torque roll and shaft vibration.
> *if* the Japanese had enough time, than perhaps it might have had a chance, but to be honest, I doubt it. Like many other nations, they had jets in the works and the efforts to address the Shiden's problems might not have been worth it.


Sure the Do335 should be listed as a pusher, was faster on the rear engine than the front.

Turbojet engine made all prop fighter planes obsolete, not just pushers.


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## swampyankee (Feb 14, 2021)

There are some cases where pushers may make sense, _e.g._, when one needs to maintain laminar flow over a fuselage, or have a wide, unobstructed view, such as the Edgely Optica (By Nigel Ish - Own work, CC BY-SA 3.0, File:Edgley Optica Sywell 1.jpg - Wikimedia Commons)






Other than these special cases, there's really very little to recommend pushers.


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## Shortround6 (Feb 14, 2021)

Well, they ended the Fokker scourge.

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## pbehn (Feb 14, 2021)

Shortround6 said:


> Well, they ended the Fokker scourge.
> 
> View attachment 612702


I am starting to see some laminar flow there.


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## Zipper730 (Apr 6, 2021)

*On the B-26*


Greg Boeser said:


> The short, symmetrical wing was chosen because that met the Army's requirements for high speed, but at the cost of higher stall speeds, longer take offs. The B-25 used a more conventional airfoil and though it cost speed, it improved low speed handling, improved take off performance.


I was thinking about that. The Mosquito was made with an airfoil that was pre laminar-flow but still a good airfoil that was not a symmetrical airfoil. Did we have anything equivalent in the United States?

I would say that the design would have profited off the following features

Fowler flaps
Having some kind of bomb-bay that was a big cavernous arrangement like the Mitchell

*On the He 177*


wuzak said:


> Not sure if the Jumo 211 had been developed into a double engine, as the DB 601 was with the DB 606.
> 
> Unless you are talking of having the He 177 with 4 separate engines.


Yeah, it seems that 4 engines makes the most sense for something that large. I'm not really sure why they came to the belief that 2 engines were inadequate.


*On the XP-49*

Would there have been some wisdom in evolving the aircraft into an all-new design rather than simply putting new-engines on the existing frame?

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## pbehn (Apr 6, 2021)

Zipper730 said:


> *On the He 177*
> Yeah, it seems that 4 engines makes the most sense for something that large. I'm not really sure why they came to the belief that 2 engines were inadequate.


The He 177 had 4 engines, they just drove 2 props. There were theoretical advantages to joining two engines together but outweighed by the problems caused by the way they did it.


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## Zipper730 (Apr 6, 2021)

pbehn said:


> The He 177 had 4 engines, they just drove 2 props.


Good point, but I think having four props is better -- even if one engine gets struck, you still have three that will run right. Also, the Jumo engines apparently (according to 

 Snowygrouch
) had a higher coolant pressure which would reduce cooling drag.

Admittedly, I know that Heinkel had an interest in an evaporatively cooled DB600/601 engine. While that would provide a theoretical edge, it wouldn't survive combat.


> There were theoretical advantages to joining two engines together


3% reduction in drag from what I was told


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## pbehn (Apr 6, 2021)

Zipper730 said:


> Good point, but I think having four props is better -- even if one engine gets struck, you still have three that will run right. Also, the Jumo engines apparently (according to
> 
> Snowygrouch
> ) had a higher coolant pressure which would reduce cooling drag.
> ...


Also stuff about suitability as a dive bomber which is above my pay grade.

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## XBe02Drvr (Apr 6, 2021)

pbehn said:


> Also stuff about suitability as a dive bomber which is above my pay grade.


"All bombers must be dive bombers! Der sturtzkampflugzug ist die grosseste waffe."

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## pbehn (Apr 6, 2021)

SaparotRob
I wasn't actually joking. There are arguments about concentration of weight and wing structure, plus things about the controllability of a twin with large props versus a four with smaller spread out props. The He 177 wasn't intended to do vertical dives but inclined at about 30 degrees to increase speed and accuracy. I have read the stuff, I have no idea if it is valid or how valid it may be. In fact the He 177 did use this to some extent, they started outside RADAR space at high altitude and the whole raid was a shallow dive, increasing speed across UK and exiting at a much lower level and higher speed than just level flight would allow.


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## Simon Thomas (Apr 6, 2021)

Zipper730 said:


> *On the B-26*
> I was thinking about that. The Mosquito was made with an airfoil that was pre laminar-flow but still a good airfoil that was not a symmetrical airfoil. Did we have anything equivalent in the United States?


The NACA M6 airfoil was rather close.




RAF 34 AIRFOIL (raf34-il)
NACA M6 (nacam6-il)

Interesting that I believe Max Munk developed the M6 in the 20's when he was working at NACA. He, like Glauert who developed the RAF 30 series, was a theoretical aerodynamicist.
When Jacobs took over, NACA started making families of airfoils based on physical parameters as well.

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## SaparotRob (Apr 6, 2021)

pbehn said:


> SaparotRob
> I wasn't actually joking. There are arguments about concentration of weight and wing structure, plus things about the controllability of a twin with large props versus a four with smaller spread out props. The He 177 wasn't intended to do vertical dives but inclined at about 30 degrees to increase speed and accuracy. I have read the stuff, I have no idea if it is valid or how valid it may be. In fact the He 177 did use this to some extent, they started outside RADAR space at high altitude and the whole raid was a shallow dive, increasing speed across UK and exiting at a much lower level and higher speed than just level flight would allow.


It was the “above my pay grade” comment I found amusing. The rest of that post was above my IQ grade.

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## Zipper730 (May 28, 2021)

pbehn said:


> Also stuff about suitability as a dive bomber which is above my pay grade.


Is there any members here who are knowledgeable about such things?


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## pbehn (May 28, 2021)

Zipper730 said:


> Is there any members here who are knowledgeable about such things?


Maybe but I doubt it apart from theoretical stuff, no one alive has practical experience of the difference between two and four engined aircraft used as dive bombers. What I read on wiki seemed logical, but could be very clever horth thit.


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## Zipper730 (May 28, 2021)

pbehn said:


> Maybe but I doubt it apart from theoretical stuff, no one alive has practical experience of the difference between two and four engined aircraft used as dive bombers.


I figure if you don't have practical, then theoretical is fine.


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## pbehn (May 28, 2021)

Zipper730 said:


> I figure if you don't have practical, then theoretical is fine.


I think it was all theoretical, did anyone ever do serious dive bombing in four engined ww2 bombers and evaluate the difference to something like a He177?


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## Zipper730 (May 29, 2021)

pbehn said:


> I think it was all theoretical, did anyone ever do serious dive bombing in four engined ww2 bombers and evaluate the difference to something like a He177?


What would intrinsically stop a 4 engined plane from dive-bombing? The only issue would be structural limits and, I can't see why two huge engines or four large engines would make a difference if the bomber weighs around the same amount.


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## pbehn (May 29, 2021)

Zipper730 said:


> What would intrinsically stop a 4 engined plane from dive-bombing? The only issue would be structural limits and, I can't see why two huge engines or four large engines would make a difference if the bomber weighs around the same amount.


It is way above my pay grade in the subject but it is about the slowing effect of two big props against four smaller ones, then the spread of the loads on pull out from the dive, you need massively strong wings to withstand the forces of the engine weight so far from the fuselage/wing root.

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## Thumpalumpacus (May 29, 2021)

Zipper730 said:


> What would intrinsically stop a 4 engined plane from dive-bombing? The only issue would be structural limits and, I can't see why two huge engines or four large engines would make a difference if the bomber weighs around the same amount.



The weight itself. When we talk about a "3-G pullout" or "6-G turn" what is really being said is that for a short period of time, the aircraft functionally weighs that much more in that part of the envelope. So a big 4-engined bomber (two or four props, I don't think it's very different) weighing 60,000 lbs at the bottom of a dive requiring a 2-G pullout functionally weighs, for a few brief moments, 120,000 lbs -- meaning that the airframe must be designed for the stresses of that weight if you want it to do that maneuver.

The bitch about that with heavy bombers pulling higher Gs is that all the reinforcement you put on it to resist those strains also add a lot of weight when you're pulling Gs. And with wider spans and longer lengths, you get more leverage at high-Gs at the ends of the wings, or the tailplane. I think it's called "moment"? I'm still learning this stuff, hopefully someone can chime in with detail and fix what I've gotten wrong.

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## Zipper730 (May 29, 2021)

pbehn said:


> It is way above my pay grade in the subject but it is about the slowing effect of two big props against four smaller ones, then the spread of the loads on pull out from the dive, you need massively strong wings to withstand the forces of the engine weight so far from the fuselage/wing root.


With the He 177, I remember the drag difference was around 3%. If you're supposed to do 500 km/h, that would shave off around 15 km/h of top-speed, which isn't trivial.

As for the structural loads, i was told that the engine pods counter wing bending, which increases with g-load. I figure that would be beneficial not counterproductive. Admittedly, that knowledge comes from commercial aviation.



Thumpalumpacus said:


> The bitch about that with heavy bombers pulling higher Gs is that all the reinforcement you put on it to resist those strains also add a lot of weight when you're pulling Gs. And with wider spans and longer lengths, you get more leverage at high-Gs at the ends of the wings, or the tailplane. I think it's called "moment"? I'm still learning this stuff, hopefully someone can chime in with detail and fix what I've gotten wrong.


G-loads are a force of acceleration, in this case centrifugal as a result of changing direction. To do so requires excess lift, which has to be present to pull off the maneuver. That said, it's a structural issue for sure, and strength/weight and thrust/weight favor the small (volume favors the large).


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## XBe02Drvr (May 29, 2021)

Thumpalumpacus said:


> The bitch about that with heavy bombers pulling higher Gs is that all the reinforcement you put on it to resist those strains also add a lot of weight when you're pulling Gs. And with wider spans and longer lengths, you get more leverage at high-Gs at the ends of the wings, or the tailplane. I think it's called "moment"? I'm still learning this stuff, hopefully someone can chime in with detail and fix what I've gotten wrong.


Well said. Another factor to consider is with a high aspect ratio long wing full of heavy fuel and engines your inertial moment is going to be so great as to interfere with rolling maneuvers. Why does this matter? Look at how dive bombing (as opposed to glide bombing) is actually done. Positioning for the run in requires the pilot to keep the target in sight as he judges angles and spacing, resulting in a roll-in to the final dive, not the gentle forward bunt into the dive that armchair heavy dive bomber designers imagine. Dive bombers have shorter, lower aspect wings and weight concentrated near the CG for a reason.

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## Thumpalumpacus (May 29, 2021)

Zipper730 said:


> G-loads are a force of acceleration, in this case centrifugal as a result of changing direction.



Yeah, that's what I was getting at.



Zipper730 said:


> To do so requires excess lift, which has to be present to pull off the maneuver. That said, it's a structural issue for sure, and strength/weight and thrust/weight favor the small (volume favors the large).



Yep. Big wings are required to swing a big plane through the sky. Those same big wings come with the penalty of having to be robust enough to carry the airplane that nominally weighs thirty tons through a turn that makes the plane think it's sixty tons. 

As others have noted above, He-177s used much more a glide profile for attack. I bet wing-loading at pullout would be too much for steeper attacks.


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## Thumpalumpacus (May 29, 2021)

XBe02Drvr said:


> Well said. Another factor to consider is with a high aspect ratio long wing full of heavy fuel and engines your inertial moment is going to be so great as to interfere with rolling maneuvers. Why does this matter? Look at how dive bombing (as opposed to glide bombing) is actually done. Positioning for the run in requires the pilot to keep the target in sight as he judges angles and spacing, resulting in a roll-in to the final dive, not the gentle forward bunt into the dive that armchair heavy dive bomber designers imagine. Dive bombers have shorter, lower aspect wings and weight concentrated near the CG for a reason.



That really makes sense to a layman like me. I hadn't considered that aspect at all.


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## Zipper730 (May 30, 2021)

Thumpalumpacus said:


> As others have noted above, He-177s used much more a glide profile for attack.


In practice, I'm not sure if the aircraft ever used dive-bombing attacks. That said, the aircraft was able to pull a normal rated g-load of 4.0 (4.8 if you used a safety factor of 1.5) with an ultimate load of 7.2 (the Germans, for reasons I'm not clear, used a safety factor of 1.8)


> I bet wing-loading at pullout would be too much for steeper attacks.


Wing loading is the ratio of weight to wing area. You're talking about g-load, or structural loads, but I know what you mean.


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## Thumpalumpacus (May 30, 2021)

Zipper730 said:


> Wing loading is the ratio of weight to wing area. You're talking about g-load, or structural loads, but I know what you mean.



As the functional weight increases due to g-loading, so does the wing loading.


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## pbehn (May 30, 2021)

Zipper730 said:


> In practice, I'm not sure if the aircraft ever used dive-bombing attacks. That said, the aircraft was able to pull a normal rated g-load of 4.0 (4.8 if you used a safety factor of 1.5) with an ultimate load of 7.2 (the Germans, for reasons I'm not clear, used a safety factor of 1.8)
> Wing loading is the ratio of weight to wing area. You're talking about g-load, or structural loads, but I know what you mean.


I think you just stumbled upon the difference between a pound weight and a kilogramme.

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## Zipper730 (May 30, 2021)

*Regarding the V-3420*



jmcalli2 said:


> I always wondered if the XP-54 wouldn't have faired better with the V-3420 and ditching the "turret" in the nose. It certainly looked cool!


I'm curious when the V-3420 was first available. The first plane that flew with it off the bat might have been the P-75, which first flew 11/17/43. That said, the XB-19 was fitted with it at some point in 1943. I'm not sure if anybody has anything on that.

(The following members 
P
 pbehn
, 
S
 Shortround6
, 
W
 wuzak
might have something here).

*Regarding the Blackburn Firebrand*



Admiral Beez said:


> If there’s any pre-jet era FAA aircraft that desperately needed intervention it’s the Blackburn Firebrand.


It definitely could have used quite a number of refinements. From what I understand, it was designed as a single-seat, high-performance fighter to defend naval bases, but also could be carrier suitable, with a considerable endurance demanded.


> _“In test pilot and naval aviator Captain Eric Brown's opinion the aircraft was "short of performance, sadly lacking in manoeuvrability, especially in rate of roll".[12] The position of the cockpit even with the trailing edge of the wing gave the pilot a very poor view over the nose, inhibited his ability to view his target and to land his aircraft aboard a carrier, sufficient for Brown to call it "a disaster as a deck-landing aircraft".[13]”_


Why the poor over the nose visibility to start with?

*Regarding the B-26*



Simon Thomas said:


> The NACA M6 airfoil was rather close.


While I'm not sure why the NACA M6 wouldn't have been usable on the B-26, I think it would have been a good fit, and with mods, it could have probably been refined into something similar to the RAF 34.

I remember another member (

 Greg Boeser
?) who appeared to have suggested the use of fowler flaps. I'm mixed on that. On one hand, it would have lowered increased the wing-area, but on the other hand -- it might have made the wing weaker (requiring additional beefening).


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## pbehn (May 30, 2021)

look at it Interesting facts about the Blackburn Firebrand

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## pbehn (May 30, 2021)

Zipper730 said:


> With the He 177, I remember the drag difference was around 3%. If you're supposed to do 500 km/h, that would shave off around 15 km/h of top-speed, which isn't trivial.
> 
> As for the structural loads, i was told that the engine pods counter wing bending, which increases with g-load. I figure that would be beneficial not counterproductive. Admittedly, that knowledge comes from commercial aviation.
> 
> G-loads are a force of acceleration, in this case centrifugal as a result of changing direction. To do so requires excess lift, which has to be present to pull off the maneuver. That said, it's a structural issue for sure, and strength/weight and thrust/weight favor the small (volume favors the large).


Wiki says this from Heinkel He 177 Greif - Wikipedia In the section on engines.
"A four-engine version would have been possible with engines like the Daimler-Benz DB 601 but the four-engine layout would impose higher propeller drag to the detriment of performance in dive bombing. "


The ins and outs of what propeller drag is and what it means are way above what I know or even want to know.

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## MiTasol (May 30, 2021)

pbehn said:


> look at it Interesting facts about the Blackburn Firebrand
> View attachment 625425


Too bad the author did such sloppy research and writes so poorly. Could have been a much better article if the many mistakes like _after equipping the aircraft with a Centaurus VII inline position engine _had been edited by someone who knows that the Centaurus is a radial and left out the redundant word _position_.

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## pbehn (May 30, 2021)

MiTasol said:


> Too bad the author did such sloppy research and writes so poorly. Could have been a much better article if the many mistakes like _after equipping the aircraft with a Centaurus VII inline position engine _had been edited by someone who knows that the Centaurus is a radial and left out the redundant word _position_.


I was just looking at the pictures, it has the canopy of a Reno racer.


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## XBe02Drvr (May 30, 2021)

Zipper730 said:


> Why the poor over the nose visibility to start with?


Are you asking why that visibility Is considered poor, or why did they build it that way? The first part of that question is obvious. Put yourself in that little cubbyhole almost back in the tail with your eyes only inches above the fuselage top and that big round engine sticking away out in front. Nuff said.




As for why they designed it that way, think of CG and fixed vs variable loads. Which would you rather have sitting on the CG, fuel or pilot? Got it?


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## Thumpalumpacus (May 30, 2021)

pbehn said:


> look at it Interesting facts about the Blackburn Firebrand
> View attachment 625425



This needs an "oh s**t" likey-button.


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## Shortround6 (May 30, 2021)

Zipper730 said:


> Why the poor over the nose visibility to start with?









Engine and placement of the main fuel tank. 
Changing to the radial did not help.


----------



## Conslaw (May 30, 2021)

Zipper730 said:


> *Regarding the V-3420*
> 
> I'm curious when the V-3420 was first available. The first plane that flew with it off the bat might have been the P-75, which first flew 11/17/43. That said, the XB-19 was fitted with it at some point in 1943. I'm not sure if anybody has anything on that.
> .



Well, it depends on what you mean by "available". The V-3420 was never set up for mass production It had commonality with the V-1710, but if you stole V-1710 production for the V-3420, you wouldn't have had as many P-38s, P-40s, P-39s, P-63s. There was only one plant building V-1710s (Indianapolis). Setting up a large bomber engine plant was a huge undertaking, witness the big R-3350 engine plant in Chicago.


----------



## Zipper730 (May 30, 2021)

*Re: He 177 Grief*



pbehn said:


> "A four-engine version would have been possible with engines like the Daimler-Benz DB 601 but the four-engine layout would impose higher propeller drag to the detriment of performance in dive bombing."


Hang on, I thought the drag was the installation (carburetor intake, radiator, oil-cooler) not the propeller? Is a larger propeller similar in effect to a wing with higher aspect ratio?

Regardless, I would have figured that higher drag would be beneficial in the dive phase as it acts like a brake a little bit. I'd have figured the problem would be during the cruise phase.

*Re: Blackburn Firebrand*



Shortround6 said:


> Engine and placement of the main fuel tank.


I guess it would have been preferable to put more fuel in the wings to avoid this?

*Re: V-3420*



Conslaw said:


> Well, it depends on what you mean by "available".


I figure used in an aircraft for a starting point.


> The V-3420 was never set up for mass production It had commonality with the V-1710, but if you stole V-1710 production for the V-3420, you wouldn't have had as many P-38s, P-40s, P-39s, P-63s.


I would have figured they'd have just built another factory to be honest.

I'm kind of tired, but I'd almost swear I was told once by somebody online that the original idea was to simply use 2 x V-1710 blocks, and it started out as an X-cylinder engine, but for one reason, it ended up as a W.

Why was this?


----------



## wuzak (May 31, 2021)

Zipper730 said:


> I figure used in an aircraft for a starting point.



I'm sure it flew in a test bed before it made its way into the XB-19A.




Zipper730 said:


> I would have figured they'd have just built another factory to be honest.



A factory was built for the IV-1430, but that never went into production.

Instead, other engines were built there - a radial (not sure which one) and then the V1-650 Merlin.

If needs must, that factory could have been converted to production of the V-1710 and V-3420.




Zipper730 said:


> the original idea was to simply use 2 x V-1710 blocks, and it started out as an X-cylinder engine, but for one reason, it ended up as a W.
> 
> Why was this?



The original scheme was for the X-3420, which was an X engine, using four V-1710 cylinder banks and heads on a crankcase that had a single crankshaft. Each bank had 6 cylinders. The angles between the banks were not 90° like the Vulture, but I can't recall what the angle were.

The X-3420 was also to be direct injected, as was the goal at the time for the V-1710 as well.

Allison produced a mock-up of the engine, but I don't think they built a running example.

It may have been due to a change in personnel that saw Allison counter-propose the V-3420. The reasoning was that using twin crankshafts, and 60° between two banks either side there were more components that could be carried over from the V-1710. It was also though that more power would be available, due to stronger crankshafts and connection rods - which would be the master and slave type for the X-3420. The projected power output was, simply, twice the output of the V-1710 at the time. Which meant 2,000hp for the V-3420 at that time, as compared to 1,600hp estimated for the X-3420.

The V-3420 was expected to be cheaper and easier to build, and be available for production sooner, due to the higher number of shared components.

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## Conslaw (May 31, 2021)

I don't know about the technical details of the V-3420. Based on the performance of the prototype engines, which did pretty well, I think there were likely two related reasons it didn't go forward. First the R-3350 was a bit ahead in development and (2) without an earmarked plant by 1942, there was no place to build it. As it turns out, it wasn't needed and the powers that be made the right call.


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## pbehn (May 31, 2021)

Zipper730 said:


> *Re: He 177 Grief*
> 
> Hang on, I thought the drag was the installation (carburetor intake, radiator, oil-cooler) not the propeller? Is a larger propeller similar in effect to a wing with higher aspect ratio?
> 
> Regardless, I would have figured that higher drag would be beneficial in the dive phase as it acts like a brake a little bit. I'd have figured the problem would be during the cruise phase.


I have no idea, the world of propellers is lost on me, it is a science in itself. I do know that an engine that is shut down with an un feathered prop causes massive drag. But that is my limit of "expertise".


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## XBe02Drvr (May 31, 2021)

pbehn said:


> I do know that an engine that is shut down with an un feathered prop causes massive drag.


Commonly known as "windmilling". Akin to using engine braking to slow a motor vehicle. A similar phenomenon exists when an airplane wants to go faster (perhaps in a dive) than the speed its propeller governed at redline and full throttle would naturally pull it. Now the tail is wagging the dog and the prop is creating lots of drag and abusing the reverse thrust bearing in the engine, which in engines not designed for reversible props is often much less robust than the main thrust bearing, if it exists at all.
That's why planes like that are required to carry power in the dive, and if steep dive bombing, need some variety of aerodynamic speed limiting.
Now imagine an 80-90 thousand pound four engine bomber engaging in such antics and "diminishing returns" comes to mind, doesn't it?

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## pbehn (May 31, 2021)

XBe02Drvr said:


> Commonly known as "windmilling". Akin to using engine braking to slow a motor vehicle. A similar phenomenon exists when an airplane wants to go faster (perhaps in a dive) than the speed its propeller governed at redline and full throttle would naturally pull it. Now the tail is wagging the dog and the prop is creating lots of drag and abusing the reverse thrust bearing in the engine, which in engines not designed for reversible props is often much less robust than the main thrust bearing, if it exists at all.
> That's why planes like that are required to carry power in the dive, and if steep dive bombing, need some variety of aerodynamic speed limiting.
> Now imagine an 80-90 thousand pound four engine bomber engaging in such antics and "diminishing returns" comes to mind, doesn't it?


That bit I understand, its when it comes to how a constant speed prop behaves when overspeeding in a dive I havnt a clue. The proposition is that two large props are better than 4 small ones. I understand the logic of the argument having that braking effect close to the centre of gravity (and all the other centres too) is beneficial. But if some learned fellow were to propose that it was advantageous to have this breaking effect spread by four props along the wing, I would have to agree with that too because I just dont know.


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## Greg Boeser (May 31, 2021)

Pilots in the Aleutians learned to use the braking power of their propellers to decrease their landing rolls in B-26s. They would cut the engines on touchdown, then restart them when they needed the power to taxi. This got a few pilots in trouble when they rotated back to the States, where such unorthodox methods were frowned upon. They also found that while the technique worked on the Pratt and Whitney equipped B-26s, it didn't work so well on the Wright equipped B-25s.

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## XBe02Drvr (May 31, 2021)

Greg Boeser said:


> while the technique worked on the Pratt and Whitney equipped B-26s, it didn't work so well on the Wright equipped B-25s.


Wright engines weren't famous for their strong reverse thrust bearings.



Greg Boeser said:


> Pilots in the Aleutians learned to use the braking power of their propellers to decrease their landing rolls in B-26s. They would cut the engines on touchdown, then restart them when they needed the power to taxi. This got a few pilots in trouble when they rotated back to the States, where such unorthodox methods were frowned upon.


No wonder! That's a great way to shock cool engines and crack cylinders.

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## XBe02Drvr (May 31, 2021)

pbehn said:


> But if some learned fellow were to propose that it was advantageous to have this breaking effect spread by four props along the wing, I would have to agree with that too because I just dont know.


(Another restating the obvious!) If you have your braking effect props spread out, they become more susceptible to a slight imbalance in drag, especially in the outboard ones, making aircraft control and thus, bombing accuracy, difficult.
Otherwise it's just comparative pi r□'s of the propeller disks.

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## pbehn (May 31, 2021)

XBe02Drvr said:


> (Another restating the obvious!) If you have your braking effect props spread out, they become more susceptible to a slight imbalance in drag, especially in the outboard ones, making aircraft control and thus, bombing accuracy, difficult.
> Otherwise it's just comparative pi r□'s of the propeller disks.


Thats easy for you to say because you know what you are talking about, flaps and other devices are frequently spread along the wings, so if some fellow of letters was to say "four engines are advantageous in dive bombing due to the spanwise spreading of loads and limiting of maximum beam stresses" (or some other BS) I couldnt say that its wrong. Like the stuff you just posted about bearing loads and shock cooling, its all very complicated lols.

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## Zipper730 (May 31, 2021)

XBe02Drvr said:


> Commonly known as "windmilling". Akin to using engine braking to slow a motor vehicle. A similar phenomenon exists when an airplane wants to go faster (perhaps in a dive) than the speed its propeller governed at redline and full throttle would naturally pull it. Now the tail is wagging the dog and the prop is creating lots of drag and abusing the reverse thrust bearing in the engine, which in engines not designed for reversible props is often much less robust than the main thrust bearing, if it exists at all.


So the matter is that the windmilling effect would produce higher drag in dives, which normally is good, but it would put excessive stress on the engine?

Still, with a drag difference of 3%, would it be that serious? The He 177 already had dive-brakes, and they weren't all that big compared to the Ju 88.


> Now imagine an 80-90 thousand pound four engine bomber engaging in such antics and "diminishing returns" comes to mind, doesn't it?


Truthfully the dive-requirement was added only after the aircraft had passed the mockup. Early on the plane was configured to perform some degree of glide-bombing (the Germans called it light to moderate angle dive-bombing), which I'm unclear on the exact number (though 40-50 degrees was a figure I heard once).

The dive-bombing requirement was added (supposedly) after the plane had been evaluated at a mock-up. Supposedly after the mock-up went okay: Udet told Heinkel the plane wouldn't be needed! Despite this, Udet said he was okay with the plane being used for other roles, including maritime patrol, but it'd require dive-bombing capability. Heinkel flat-out told Udet that the aircraft would never be capable of the 60-degree dive-requirement.

From what I remember reading, the idea to demand dive-bombing for all bomber aircraft seemed to have come out of the Spanish Civil War: The idea was that a dive-bomber could heap more bombs on target than level-bombing. Interestingly, the Germans didn't seem to devote much effort to bombsights early on.


> If you have your braking effect props spread out, they become more susceptible to a slight imbalance in drag, especially in the outboard ones, making aircraft control and thus, bombing accuracy, difficult.


Technically, that could be argued to say that even a twin-engined dive-bomber would have problems in that regard.



Greg Boeser said:


> Pilots in the Aleutians learned to use the braking power of their propellers to decrease their landing rolls in B-26s. They would cut the engines on touchdown, then restart them when they needed the power to taxi. This got a few pilots in trouble when they rotated back to the States, where such unorthodox methods were frowned upon. They also found that while the technique worked on the Pratt and Whitney equipped B-26s, it didn't work so well on the Wright equipped B-25s.


Were the DB 601 or Jumo 211/213 sturdy in that regard?


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## XBe02Drvr (May 31, 2021)

Zipper730 said:


> Technically, that could be argued to say that even a twin-engined dive-bomber would have problems in that regard.


True, but the proximity of the engines to aircraft centerline tends to minimize that effect to remain within the corrective ability of the flight controls. Less so with outboard mounted engines.

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## wuzak (May 31, 2021)

Conslaw said:


> I don't know about the technical details of the V-3420. Based on the performance of the prototype engines, which did pretty well, I think there were likely two related reasons it didn't go forward. First the R-3350 was a bit ahead in development and (2) without an earmarked plant by 1942, there was no place to build it. As it turns out, it wasn't needed and the powers that be made the right call.



The problem for the V-3420 was that it wasn't always a required engine, so development wasn't continuous. Allison had limited development resources, so they concentrated on the V-1710 and the myriad variations the AAF kept asking for.

On the plus side, developments on the V-1710 were (mostly) applicable to the V-3420.

The biggest hope for production orders for the V-3420 would likely have been a production B-39. When the XB-39 program started the R-3350 wasn't very reliable. But by the time the XB-39 took its first flight most of the issues with the R-3350 were solved. But there were still issues, such as take-off performance at high loads.

The XB-39 program was also to use experimental twin stage turbos, instead of the standard type turbos that the B-29 had. That caused delay, and eventually the XP-39 flew without.

The big problem for the XB-39 was the development of the XP-75. This took Fisher away from building the engine modules for the XB-39, and also required Allison to develop the remote shaft and gearbox system and 2 stage supercharging.

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## Simon Thomas (Jun 1, 2021)

XBe02Drvr said:


> No wonder! That's a great way to shock cool engines and crack cylinders.


For current typical single and twins, the coolests operating CHTs are at touch down. Even taxiing back causes the CHT's to rise again.
I see no reason a similar behaviour would not be seen with the radials.
Shock cooling would be very unlikely in this scenario.


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## XBe02Drvr (Jun 1, 2021)

Simon Thomas said:


> I see no reason a similar behaviour would not be seen with the radials.
> Shock cooling would be very unlikely in this scenario.


Apples and oranges. Modern light aircraft in a temperate climate are not the same as heavy military aircraft operating in Alaska. The "incredible prostitute", aka "Baltimore sewer pipe", with its high wing loading would carry more power on its tightly cowled engines on the approach, and the much greater mass of the R2800 would be storing more heat. They ran hot anyway. Landing speeds were high and OATs were low; recipe for shock cooling if the engines were caged at touchdown. The effect is cumulative with repeated abuses. I've had experience towing gliders (Bird Dogs forever) and operating turbocharged planes at high altitudes in winter, as well as changing cracked cylinders. BTDT.
PS: I guess it wasn't clear above, but to get down to survivable landing speeds on short slippery Aleutian runways the Marauder had to be operated on the backside of the power curve on final, a tricky and power hungry operation. "One a day in Tampa Bay!"
Not the case with today's light aircraft.

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## Greg Boeser (Jun 1, 2021)

73rd BS lost two within minutes touching down late on a rain slick runway at Naknek, AK on 16 Aug 1942. One fatality and several injured. Both aircraft were recovered in the '70s and spent time at Hill AFB in Utah, awaiting restoration. Last I saw they were up for sale in 2018. Haven't seen any new info.

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## Dcazz7606 (Jun 3, 2021)

P-39 Airacobra. Give it a ventral radiator similar to Mustang or Ki-61 and use the space in the wings for more fuel tanks.


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## SaparotRob (Jun 3, 2021)

Uh-oh.

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## Thumpalumpacus (Jun 3, 2021)

Yeah, there be a s**tstorm a-brewin'. We'll be removing armor before you know it.

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## P-39 Expert (Jun 3, 2021)

Sorry to disappoint you.

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## SaparotRob (Jun 3, 2021)

You da' MAN!

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## pbehn (Jun 3, 2021)

Dcazz7606 said:


> P-39 Airacobra. Give it a ventral radiator similar to Mustang or Ki-61 and use the space in the wings for more fuel tanks.


The P-51 is a much bigger aircraft, the inlet is ventral but a lot of the cooling system is inside the fuselage.


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## SaparotRob (Jun 3, 2021)

I don't see the whistle.

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## pbehn (Jun 3, 2021)

SaparotRob said:


> I don't see the whistle.


You know how to whistle, don’t you? You just put your lips together, and blow.”

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## SaparotRob (Jun 3, 2021)

You get a Bacon and a side of fries, Sir!

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## pbehn (Jun 3, 2021)

SaparotRob said:


> You get a Bacon and a side of fries, Sir!


That movie was made in 1944, she obviously had the P-51D cooling system in mind.

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## XBe02Drvr (Jun 3, 2021)

SaparotRob said:


> I don't see the whistle.


Don't look, just listen.

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## Zipper730 (Jun 3, 2021)

Dcazz7606 said:


> P-39 Airacobra. Give it a ventral radiator similar to Mustang or Ki-61 and use the space in the wings for more fuel tanks.


You'd have two basic problems.

1. Volumetrics: Basically the P-51 had room in the middle of it's fuselage for the belly radiator because it had no engine there. Unless you were to place a radiator behind the engine, which might throw the C/G out of whack.

2. Belly-Landing Characteristics: The P-39 was actually pretty good in that regard (even despite having an extension shaft). Add a belly-radiator and you'd run the risk of wheel-barrowing (the nose would pitch over upon contact with the ground -- if this was in water, the results would see you exploring the watery depths).

While I don't want to get into the P-39 too much, I am curious if a design that was closer to mid-wing would have worked.


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## XBe02Drvr (Jun 3, 2021)

pbehn said:


> The P-51 is a much bigger aircraft, the inlet is ventral but a lot of the cooling system is inside the fuselage.
> View attachment 625962


And you're proposing shifting EVEN MORE weight aft??
"Holy tumbling tinkerBells, Batman, what are they thinking of?"

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## pbehn (Jun 3, 2021)

XBe02Drvr said:


> And you're proposing shifting EVEN MORE weight aft??
> "Holy tumbling tinkerBells, Batman, what are they thinking of?"


I was flirting with the dark side of forum discussions.


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## special ed (Jun 3, 2021)

Wouldn't a mid wing put the spar through the engine?


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## XBe02Drvr (Jun 3, 2021)

special ed said:


> Wouldn't a mid wing put the spar through the engine?


No, through the pilot. As it is, he appears to be sitting on it. Shift him forward. CG problem solved. Visibility improved. What's not to like?
Driveshaft a little longer, but we can live with that, can't we?

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## special ed (Jun 3, 2021)

I think you have it. A TP-39 without the aft cockpit!

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## XBe02Drvr (Jun 3, 2021)

special ed said:


> I think you have it. A TP-39 without the aft cockpit!


Groundhogs, fixed or jettisonable?

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## pbehn (Jun 3, 2021)

Why not take the Allison engine out of a P-39 swap it for a Merlin and put it into a P-51, this new variant could be called a P-39WHITHNOSEWHEELATTHEBACK?

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## XBe02Drvr (Jun 3, 2021)

pbehn said:


> Why not take the Allison engine out of a P-39 swap it for a Merlin and put it into a P-51, this new variant could be called a P-39WHITHNOSEWHEELATTHEBACK?


Coals to Newcastle. Didn't you chaps have enough Mustang Mk1s already?
Have fun Merlinizing the P39! "Exercises in futility are fun to watch."
-- Gyro Gearloose

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## FLYBOYJ (Jun 3, 2021)

I'd spin this!

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## FLYBOYJ (Jun 3, 2021)




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## pbehn (Jun 3, 2021)

XBe02Drvr said:


> Coals to Newcastle. Didn't you chaps have enough Mustang Mk1s already?
> Have fun Merlinizing the P39! "Exercises in futility are fun to watch."
> -- Gyro Gearloose


As far as I know the high altitude version of the P-39 was called (with delicious irony) the P-38, I am not an expert on the subject of numbers but I believe that 38 comes before 39.

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## XBe02Drvr (Jun 3, 2021)

FLYBOYJ said:


> View attachment 625996
> 
> 
> I'd spin this!


That should auger well for you!

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## pbehn (Jun 3, 2021)

XBe02Drvr said:


> That should auger well for you!


I saw what you did there.

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## XBe02Drvr (Jun 3, 2021)

pbehn said:


> I saw what you did there.


What? What'd I do? T'w'ant me!


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## pbehn (Jun 3, 2021)

XBe02Drvr said:


> What? What'd I do?


Well if you cant figure it out, screw you, into the nearest lawn.


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## XBe02Drvr (Jun 3, 2021)

pbehn said:


> Well if you cant figure it out, screw you, into the nearest lawn.


The dart of outrageous fortune!

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## wuzak (Jun 3, 2021)

FLYBOYJ said:


> View attachment 625996
> 
> 
> I'd spin this!



It looks similar to the MiG-3.

I was going to say to improve the P-39 you could move the engine forward, then you would also have to move the pilot forward, but that would unfortunately mean the 37mm cannon will have to be ditched.

Then move the engine forward some more. Now the pilot has run out of room, so better relocate him behind the engine.

Also, the extension shaft is getting short. Better take that out and run the prop from a reduction gear on the engine. 

Then we can install the P-51 style radiator....


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## wuzak (Jun 3, 2021)

Dcazz7606 said:


> P-39 Airacobra. Give it a ventral radiator similar to Mustang or Ki-61 and use the space in the wings for more fuel tanks.



The radiator was actually in the centre fuselage, under the engine. The ducts to the radiator, plus the oil coolers and their ducts, were in the wings.


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## XBe02Drvr (Jun 3, 2021)

wuzak said:


> It looks similar to the MiG-3.
> 
> I was going to say to improve the P-39 you could move the engine forward, then you would also have to move the pilot forward, but that would unfortunately mean the 37mm cannon will have to be ditched.
> 
> ...


...after a 15% total airframe upsize.


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## wuzak (Jun 3, 2021)

XBe02Drvr said:


> ...after a 15% total airframe upsize.



And the addition of laminar flow wings with a group of 0.50" mgs in the wings.


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## P-39 Expert (Jun 4, 2021)

FLYBOYJ said:


> View attachment 625997


Thank God the AAF chose the Model 4.


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## VA5124 (Jun 7, 2021)

what would have happened had you stuck the pratt and whintey from the corsair in the mustang


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## FLYBOYJ (Jun 7, 2021)

VA5124 said:


> what would have happened had you stuck the pratt and whintey from the corsair in the mustang


You'd have a very goofy looking airplane!

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## VA5124 (Jun 7, 2021)

FLYBOYJ said:


> You'd have a very goofy looking airplane!


but how would it have performed with the higher hp radial


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## GrauGeist (Jun 7, 2021)

VA5124 said:


> but how would it have performed with the higher hp radial


Probably similar performance as the P-47, because it was the same engine.


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## VA5124 (Jun 7, 2021)

ok plan b have the usaf adopt a verison of the corsair and the p51 never happens

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## XBe02Drvr (Jun 7, 2021)

VA5124 said:


> but how would it have performed with the higher hp radial


I would bet that the extra horsepower would have been consumed by the extra drag and loss of the Meredith effect. Also the range would suffer bigtime from the radial's higher specific fuel consumption, and high altitude performance would probably suffer as well. Witness how much more fuel the P47 required to fly the same distance as a P51.

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## GrauGeist (Jun 7, 2021)

VA5124 said:


> ok plan b have the usaf adopt a verison of the corsair and the p51 never happens


The USAAF had the P-47, didn't need a Corsair clone.


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## XBe02Drvr (Jun 7, 2021)

GrauGeist said:


> Probably similar performance as the P-47, because it was the same engine.


Same engine, but not the same powerplant. P47 was turbocharged, F4U was two speed supercharged. P47 would have more power available above the low 20s in altitude.


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## GrauGeist (Jun 7, 2021)

XBe02Drvr said:


> Same engine, but not the same powerplant. P47 was turbocharged, F4U was two speed supercharged. P47 would have more power available above the low 20s in altitude.


I kept the answer simple.


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## Dash119 (Jun 7, 2021)

XBe02Drvr said:


> I would bet that the extra horsepower would have been consumed by the extra drag and loss of the Meredith effect. Also the range would suffer bigtime from the radial's higher specific fuel consumption, and high altitude performance would probably suffer as well. Witness how much more fuel the P47 required to fly the same distance as a P51.


My understanding was that the Meredeth effect merely negated the drag created by the scoop. No scoop, no Meredith effect, no difference.


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## XBe02Drvr (Jun 7, 2021)

VA5124 said:


> ok plan b have the usaf adopt a verison of the corsair and the p51 never happens


The Corsair couldn't have done the Mustang's job of high altitude ultra long range escort. The P47 eventually got there, at the cost of lugging an inordinate amount of fuel around, but it was turbocharged, and could do it. The Corsair wasn't and couldn't. The Corsair fought a different war with different requirements.

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## wuzak (Jun 7, 2021)

VA5124 said:


> ok plan b have the usaf adopt a verison of the corsair and the p51 never happens



The P-51 happened because the British wanted more P-40s to fulfil their requirements. 

If the USAF didn't adopt the P-51, they would still have been made for Britain, and the British would have built a conversion centre to change the Allison to the Merlin.

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## wuzak (Jun 7, 2021)

VA5124 said:


> what would have happened had you stuck the pratt and whintey from the corsair in the mustang



The R-2800 was ~66% wider than the Merlin and ~25% taller and maybe about 500lb heavier.

An R-2800 in a Mustang would look odd.

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## wuzak (Jun 7, 2021)

P-39 Expert said:


> Thank God the AAF chose the Model 4.



Why?

It looks to me they have both been designed to fit a big cannon firing through the propeller, when two cowl and two wing 0.50" HMGs would have enough for most tasks, and the cannon it did end up with wasn't that great anyway.

I believe the Model 3 was designed around a proposed or imaginary 25mm cannon.

If such a cannon existed, would not 2 in the wings plus the cowl MGs be more than enough firepower?


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## XBe02Drvr (Jun 7, 2021)

Dash119 said:


> My understanding was that the Meredeth effect merely negated the drag created by the scoop. No scoop, no Meredith effect, no difference.


Well, having just read drgondog's book on the P51, the understanding I got was that the major drag negated was the radiator and oil cooler inside the scoop as well as the profile drag of the scoop itself. That means that nearly all the cooling drag of the entire powerplant was cancelled, which is HUGE. On most airplanes engine cooling represents 35-45% of total airframe drag. The only exception on the Mustang was the supercharger intercooler, which had it's own separate duct independent of the scoop. Forcing air through a heat exchanger matrix at high speed requires a lot of energy, which was recouped in the form of thrust generated by the heated air being ejected from the carefully shaped plenum. The temperature controlled variable orifice "nozzle" that maximized the thrust effect could be viewed as the great grandaddy of today's variable geometry afterburner "tailfeathers".
This gives the P51 a significant advantage over an R2800 or R3350 powered plane which still has to squirt the cooling air through the fins and baffles of 18 cylinders, then out under the cowl flaps, not to mention the oil cooler and intercooler.

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## wuzak (Jun 7, 2021)

XBe02Drvr said:


> Well, having just read drgondog's book on the P51, the understanding I got was that the major drag negated was the radiator and oil cooler inside the scoop as well as the profile drag of the scoop itself. That means that nearly all the cooling drag of the entire powerplant was cancelled, which is HUGE. On most airplanes engine cooling represents 35-45% of total airframe drag. The only exception on the Mustang was the supercharger intercooler, which had it's own separate duct independent of the scoop.



I though the intercooler radiator was with the engine radiator in the scoop, the oil cooler having its own duct.


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## VA5124 (Jun 7, 2021)

i know how to do this have the usaf adopt the f4u but supercharge the r 2800 and instead of the .50s install 6x20mm cannon perfect to use as a intercepor in both the eto and pto


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## wuzak (Jun 7, 2021)

VA5124 said:


> i know how to do this have the usaf adopt the f4u but supercharge the r 2800 and instead of the .50s install 6x20mm cannon perfect to use as a intercepor in both the eto and pto



Why?


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## P-39 Expert (Jun 7, 2021)

wuzak said:


> Why?
> 
> It looks to me they have both been designed to fit a big cannon firing through the propeller, when two cowl and two wing 0.50" HMGs would have enough for most tasks, and the cannon it did end up with wasn't that great anyway.
> 
> ...


Pilot visibility mainly.

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## XBe02Drvr (Jun 7, 2021)

wuzak said:


> I though the intercooler radiator was with the engine radiator in the scoop, the oil cooler having its own duct.


That's not what my infallible  memory says, but I've got the book handy and will look it up tomorrow. According to the arrangement drawing, the intercooler is between the two stages of the supercharger, and it seems unlikely that they would duct it all the way down to the scoop plenum and back again. In any case, does it make a difference? Oil cooler and intercooler are both relatively minor compared to the glycol radiator which carries off the vast majority of the engine heat and will generate the most drag.


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## special ed (Jun 7, 2021)

The radial in a P-51 would look and require the mods that changed the Ki-61 into the Ki-100. Result: A very different airframe.


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## wuzak (Jun 7, 2021)

XBe02Drvr said:


> That's not what my infallible  memory says, but I've got the book handy and will look it up tomorrow. According to the arrangement drawing, the intercooler is between the two stages of the supercharger, and it seems unlikely that they would duct it all the way down to the scoop plenum and back again. In any case, does it make a difference? Oil cooler and intercooler are both relatively minor compared to the glycol radiator which carries off the vast majority of the engine heat and will generate the most drag.



The intercooler is a water-to-air system, with a separate radiator for the air stream.

In the Spitfire IX the intercooler radiator is in one of the under wing radiator ducts, along with one of the radiators.


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## Shortround6 (Jun 7, 2021)

VA5124 said:


> i know how to do this have the usaf adopt the f4u but supercharge the r 2800 and instead of the .50s install 6x20mm cannon perfect to use as a intercepor in both the eto and pto



Ok the answers are out there. Or in a number of threads in the forum. 

short answers.

The 20mm gun weighs about twice as much as the .50 cal machine gun the US used. 20mm ammo weighs roughly, twice what a .50 cal ammo weighs per 100 rounds. You are proposing a substantial increase in armament weight. 

Engine used in the Corsair was good for 1650hp at around 22,000ft. P-47 engine was good for 2000hp at 25-27,000ft depending on RAM. P-47 engine needed a much more capable (larger) inter cooler and ducts. 
Engine in the F4U was two stage, not two speed, it already had one supercharger (two speed with a neutral) feeding the engine supercharger. And it had inter coolers. 

Fitting either one into the P-51 would have resulted in a new airplane.


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## VA5124 (Jun 7, 2021)

then dont fit to the p51 just adopt the f4u and dont bulid the mustsng


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## tyrodtom (Jun 7, 2021)

VA5124 said:


> then dont fit to the p51 just adopt the f4u and dont bulid the mustsng



The F4U doesn't have the range, or the ability to fight at high altitude that the Mustang has, it can't perform the mission the Mustang did.

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## XBe02Drvr (Jun 7, 2021)

VA5124 said:


> then dont fit to the p51 just adopt the f4u and dont bulid the mustsng


What have you got against the Mustang, anyway? By the time you trick out a Corsair to (almost) do the Mustang's job you have a larger, heavier, more expensive, more fuel hungry, P47 wannabe that can't quite do the job.
Sure, it has more rated horsepower, but that horsepower has to drag a larger, heavier airframe around which is less efficient than the Mustang's, and at escort altitudes (25-30,000 feet) its available power advantage has shrunk to near zero, but its airframe hasn't shrunk at all. What have you gained? The Corsair was a great machine in the type of war for which it was designed, but it wasn't the invincible super weapon you imagine.

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## VA5124 (Jun 7, 2021)

what about the idea of a twin supercharged sbd with refored wings to make it capible of carry 4x1000lb bombs


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## VA5124 (Jun 7, 2021)

XBe02Drvr said:


> What have you got against the Mustang, anyway? By the time you trick out a Corsair to (almost) do the Mustang's job you have a larger, heavier, more expensive, more fuel hungry, P47 wannabe that can't quite do the job.
> Sure, it has more rated horsepower, but that horsepower has to drag a larger, heavier airframe around which is less efficient than the Mustang's, and at escort altitudes (25-30,000 feet) its available power advantage has shrunk to near zero, but its airframe hasn't shrunk at all. What have you gained? The Corsair was a great machine in the type of war for which it was designed, but it wasn't the invincible super weapon you imagine.


 i dont i like the mustang but i perfer the corsair


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## GrauGeist (Jun 7, 2021)

VA5124 said:


> what about the idea of a twin supercharged sbd with refored wings to make it capible of carry 4x1000lb bombs


That's called a B-17...

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## VA5124 (Jun 7, 2021)

GrauGeist said:


> That's called a B-17...


im not talking about a b-17 im talking about buliding a supercharged dive bomber


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## XBe02Drvr (Jun 7, 2021)

VA5124 said:


> i dont i like the mustang but i perfer the corsair


Well I liked the F14, but that never changed the fact that when it came to an up close knife fight, the F15 would usually come out on top. My preferences couldn't change that.
On the other hand an element of F14s and an element of F15s out over the ocean searching for each other out of range from GCI or AWACS, and now it's a different ball game. In a real life combat situation the F15s would die of Phoenix venom before they got close enough to paint the Tomcats on their radar screens.
Different planes for different fights.

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## GrauGeist (Jun 7, 2021)

VA5124 said:


> im not talking about a b-17 im talking about buliding a supercharged dive bomber


The SBD could already deliver 2,250 pounds to it's target. Why try and turbosupercharge it?

Dive bombers had to limit their speed in a dive (the SBD's limit was 250mph) so they could recover from the dive. One of the fastest divers was the Stuka at a duve speed of a little over 300mph.

Stuffing a monster engine in it won't change that.

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## VA5124 (Jun 7, 2021)

GrauGeist said:


> The SBD could already deliver 2,250 pounds to it's target. Why try and turbosupercharge it?
> 
> Dive bombers had to limit their speed in a dive (the SBD's limit was 250mph) so they could recover from the dive. One of the fastest divers was the Stuka at a duve speed of a little over 300mph.
> 
> Stuffing a monster engine in it won't change that.


thats the best way i can think to make it a better bomber


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## GrauGeist (Jun 7, 2021)

VA5124 said:


> thats the best way i can think to make it a better bomber


You can't fix perfection - the SBD broke the back of the Imperial Japanese Navy by sinking 4 fleet carriers and 2 light carriers, not to mention other warships.

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## XBe02Drvr (Jun 7, 2021)

VA5124 said:


> thats the best way i can think to make it a better bomber


You need to learn a little more about engines and aerodynamics.
The SBD already had a supercharger built right into its engine. In mechanic school we took a Wright R1820 (the engine the SBD used) apart, put it back together, and ran it. Adding a turbo to it won't give you more performance at the altitudes a WWII dive bomber operated at, only at higher altitudes where it has no need to go.
There's not much value in carrying multiple bombs, as the plane normally gets only one pass on a defended target. One 2,000 pound bomb is more effective against a hardened target than two 1,000 pounders.
There's a wealth of information in the various threads on this site. Read up.

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## ThomasP (Jun 7, 2021)

Hey VA5124, check these out.

AM-1 Mauler
3x2000 lb torpedoes and 12x250 lb bombs, for a total of 9,000 lb payload






AD-1 Skyraider
3x2000 lb bombs, 6x500 lb bombs, and 6x250 lb bombs, for a total of 10,500 lb payload

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## Shortround6 (Jun 7, 2021)

And not a turbo in sight


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## XBe02Drvr (Jun 7, 2021)

XBe02Drvr said:


> That's not what my infallible  memory says, but I've got the book handy and will look it up tomorrow.


Guess I shouldn't trust my memory. According to the drawings on page 304 and 306 of _P51B Mustang _by our very own drgondog, the two stage Merlin supercharger has *two *coolers, an intercooler between stages, which is integral to the supercharger housing, and an aftercooler after the second stage, which is plumbed to a radiator adjacent to the glycol radiator in the belly scoop. The oil cooler is mounted in a separate duct in the belly scoop forward of and below the glycol/aftercooler radiator.
Thus it appears the belly scoop is handling nearly all of the powerplant cooling load and converting it to thrust. (When the belly scoop's rear exit auto-adjust scoop is working right!)

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## Admiral Beez (Jun 7, 2021)

GrauGeist said:


> You can't fix perfection - the SBD broke the back of the Imperial Japanese Navy by sinking 4 fleet carriers and 2 light carriers, not to mention other warships.


Given the circumstances of thirty-one USN dive-bombers arriving at the ideal time, location and altitude with zero HA CAP to counter them and IJN CVs in disarray with vulnerable aircraft and unsecured fuel and bombs, I would argue that pretty much any dive bomber could have done the job. Replace those Dauntless with Vought SB2U Vindicator or Blackburn Skuas and the results should be about the same.


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## pbehn (Jun 7, 2021)

Admiral Beez said:


> Given the circumstances of thirty-one USN dive-bomber squadrons arriving at the ideal time, location and altitude with zero HA CAP to counter them and IJN CVs in disarray with vulnerable aircraft and unsecured fuel and bombs, I would argue that pretty much any dive bomber could have done the job. Replace those Dauntless with Vought SB2U Vindicator or Blackburn Skuas and the results should be about the same.


That is not how history works.

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## GrauGeist (Jun 7, 2021)

Admiral Beez said:


> Given the circumstances of thirty-one USN dive-bomber squadrons arriving at the ideal time, location and altitude with zero HA CAP to counter them and IJN CVs in disarray with vulnerable aircraft and unsecured fuel and bombs, I would argue that pretty much any dive bomber could have done the job. Replace those Dauntless with Vought SB2U Vindicator or Blackburn Skuas and the results should be about the same.


(just a head's-up: you might want to fix that "31 squadrons" thing)

The SBDs were diving at between 80 and 70 degrees in the Midway attack.
Any other dive-bomber (Stuka excluded) would have a higher chance of being spotted on it's approach due to a shallower dive angle.
That being said, the SBD sank two carriers that did have CAP as well as protected troop transports, Cruiser and so on.

The fact that all got through was due to the lack of CAP and they proceeded to overkill the carriers. It would have only taken several of them to do the job and the A6Ms, no matter how hard they tried, would not have been able to stop all of them.

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## XBe02Drvr (Jun 7, 2021)

Admiral Beez said:


> Given the circumstances of thirty-one USN dive-bomber squadrons arriving at the ideal time, location and altitude with zero HA CAP to counter them


Huh? Where did you come up with *thirty-one squadrons *of SBDs?? Each carrier had two SBD squadrons, a bombing (VB) and a scouting (VS), which was also a trained dive bombing squadron. Hornet's two SBD squadrons never made the scene, but one from Midway did. The Midway squadron were rookies, new to dive bombing and new to the aircraft, with predictable results. Adds up to five squadrons in my book.
They were fortunate in that the CAP, while fairly strong at 42, was scattered and distracted (not all at low altitude, as common mythology asserts), but the scattered-to-broken cloud deck and the Japanese lack of effective radar obscured their approach. Given equally competent crews, Vindicators or Skuas, with their slower speeds and lighter payloads would likely have been hard put to match that performance.


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## SaparotRob (Jun 7, 2021)

Perhaps 31 SBD's? I don't recall the exact number of Dauntless's but I'm sure the Admiral didn't mean squadrons.

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## GrauGeist (Jun 7, 2021)

The problem with the Midway based SBDs and SB2Us during the battle, is that they did not follow their training and attack from a high altitude, instead attacking from a much lower elevation.
This not only alerted the Japanese to their presence, but allowed the CAP to interdict before getting into position.

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## SaparotRob (Jun 7, 2021)

It may have been lack of training. I recall reading that the Midway based SBD's were new pilots and their CO (It's bugging me that I can't remember his name) did a glide bombing attack due to their inexperience. I'm going to have to do some reading.

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## Zipper730 (Jun 7, 2021)

wuzak said:


> I'm sure it flew in a test bed before it made its way into the XB-19A.


It was merely the first aircraft that I knew it flew on, though I'm not sure the exact timeframe.


> If needs must, that factory could have been converted to production of the V-1710 and V-3420.


That's good to know. Honestly, I'm curious to know how hard it would have been for US Army to have simply changed the hyper-engine from single to monoblock construction?


> The original scheme was for the X-3420, which was an X engine, using four V-1710 cylinder banks and heads on a crankcase that had a single crankshaft. Each bank had 6 cylinders. The angles between the banks were not 90° like the Vulture, but I can't recall what the angle were.
> 
> The X-3420 was also to be direct injected, as was the goal at the time for the V-1710 as well.


What advantages come with direct injection vs. the pressure carburetor?


> It may have been due to a change in personnel that saw Allison counter-propose the V-3420. The reasoning was that using twin crankshafts, and 60° between two banks either side there were more components that could be carried over from the V-1710. It was also though that more power would be available, due to stronger crankshafts and connection rods - which would be the master and slave type for the X-3420.


I'm guessing having an X-cylinder with 2-sets of 60-degrees between them top and bottom would be more difficult to pull off? What's a master and slave type rod, and what would make it weaker than the twin-crankshafts of the X-3420?


> The V-3420 was expected to be cheaper and easier to build, and be available for production sooner, due to the higher number of shared components.


How much earlier would you have guessed?


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## GrauGeist (Jun 7, 2021)

SaparotRob said:


> It may have been lack of training. I recall reading that the Midway based SBD's were new pilots and their CO (It's bugging me that I can't remember his name) did a glide bombing attack due to their inexperience. I'm going to have to some reading.


Maj. Henderson USMC (Henderson field was named in his honor)


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## Zipper730 (Jun 7, 2021)

XBe02Drvr said:


> The SBD already had a supercharger built right into its engine.


Yeah, almost all WWII engines had an integral supercharger built into them.


> Adding a turbo to it won't give you more performance at the altitudes a WWII dive bomber operated at, only at higher altitudes where it has no need to go.


I'd stipulate to the argument that, later in the war, with proposed single-engined dive-bomber/attack aircraft (like the XA-41), that an improved supercharger would have been useful since the fighters were now able to go higher, the attack planes should be able to cruise higher too, as it'd give them better performance.


> There's not much value in carrying multiple bombs, as the plane normally gets only one pass on a defended target. One 2,000 pound bomb is more effective against a hardened target than two 1,000 pounders.


Generally speaking, land-based dive-bombers usually tended to have multiple smaller bombs (ranging from about 110-500 lb. typically), whereas naval dive-bombers usually were built around carrying larger bombs (500 lb. to 1600 lb., maybe 2000 lb.) because land-based dive-bombers would probably be aiming at things like tanks, pill-boxes, and people (with the occasional bridge). People are, for better or worse, soft and squishy and, while tanks are armored, they seem easier to destroy than ships.

I have no idea how sturdy a typical pillbox or a bridge of WWII vintage was.


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## SaparotRob (Jun 7, 2021)

GrauGeist said:


> Maj. Henderson USMC (Henderson field was named in his honor)


And that’s why it was bugging me. Senility sucks.


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## Admiral Beez (Jun 7, 2021)

XBe02Drvr said:


> Huh? Where did you come up with *thirty-one squadrons *of SBDs??


That’s your contribution? 


GrauGeist said:


> (just a head's-up: you might want to fix that "31 squadrons" thing)
> 
> The SBDs were diving at between 80 and 70 degrees in the Midway attack.
> Any other dive-bomber (Stuka excluded) would have a higher chance of being spotted on it's approach due to a shallower dive angle.
> ...


Thanks Grau. I had started as three squadrons but edited to the number of aircraft instead.

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## pbehn (Jun 7, 2021)

Admiral Beez said:


> That’s your contribution?
> .


Obviously not, you edited out the rest of his contribution? Here it is, " Each carrier had two SBD squadrons, a bombing (VB) and a scouting (VS), which was also a trained dive bombing squadron. Hornet's two SBD squadrons never made the scene, but one from Midway did. The Midway squadron were rookies, new to dive bombing and new to the aircraft, with predictable results. Adds up to five squadrons in my book.
They were fortunate in that the CAP, while fairly strong at 42, was scattered and distracted (not all at low altitude, as common mythology asserts), but the scattered-to-broken cloud deck and the Japanese lack of effective radar obscured their approach. Given equally competent crews, Vindicators or Skuas, with their slower speeds and lighter payloads would likely have been hard put to match that performance. " Though I dont see how this type of discussion moves anything on.

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## GrauGeist (Jun 7, 2021)

And an interesting side-note regarding the Battle of Midway:
The SBD pilots were using the Hinomaru painted on the Carriers' deck as their primary aim-point.
Shortly after the battle, the IJN removed it from their other carriers.

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## Greg Boeser (Jun 7, 2021)

The SBDs at Midway got lucky, their success won by the sacrifice of dozens of torpedo bomber crews and land based dive bombers. 
Nothing occurs in a vacuum.
A5Ms were shooting down SBDs in the Marshalls in February 1942, Zeroes claimed quite a few at Coral Sea and in the Solomons. They weren't invincible.


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## VA5124 (Jun 7, 2021)

Greg Boeser said:


> The SBDs at Midway got lucky, their success won by the sacrifice of dozens of torpedo bomber crews and land based dive bombers.
> Nothing occurs in a vacuum.
> A5Ms were shooting down SBDs in the Marshalls in February 1942, Zeroes claimed quite a few at Coral Sea and in the Solomons. They weren't invincible.


 if you would bulid it like i said it would have been better


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## Greg Boeser (Jun 7, 2021)

They did. It is called the AD-1 Skyraider.


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## BiffF15 (Jun 7, 2021)

XBe02Drvr said:


> Well I liked the F14, but that never changed the fact that when it came to an up close knife fight, the F15 would usually come out on top. My preferences couldn't change that.
> On the other hand an element of F14s and an element of F15s out over the ocean searching for each other out of range from GCI or AWACS, and now it's a different ball game. In a real life combat situation the F15s would die of Phoenix venom before they got close enough to paint the Tomcats on their radar screens.
> Different planes for different fights.



Let me dispel a myth or two from a bit more modern era. Contrary to what Tomcat guys claim, the AIM-54 was not the end all be all missile. It was designed to kill large, mostly unaware bomber aircraft from great distances. It was used in combat by the US only twice, both in 1999, all missiles fired missing. The Iranians had a bit more success, claiming 70+ AIM-54 kills against... Iraqi's. Use Operation Desert Storm Iraqi Air Force statistics as a measuring tape to their training proficiency.

What the F-14s radar, the AWG-9, was designed to do was launch AIM-54s out of a radar mode known as TWS (Track While Scan pronounced TWiS). TWS allowed targeting of multiple aircraft by one (aircraft) or Tomcat. In the early 90s, when I first started fighting them it was call Track While Lie. Other TWS equipped fighters radar would tell (indicate to) the pilot when it had low confidence something was actually being tracked. Not the Tomcat. TWS also fooled most Radar Warning Receivers (RWR) on fighters until the advent of the ALR-56C on the F-15C model. I spoke with my Kadena buddies about fighting it in large force exercises (LFEs). The consensus was not good. They routinely called kills and no one was near where they thought their opponent was (hence the Track While Lie reputation). Also of note is their radar was High Pulse Repetition Frequency (HPRF) only. HPRF only sees things closing towards it, and in the case of the AWG-9, did not do well over land either. Targets maneuvering near the beam or less aspect it REALLY had a tough time. The F-15 & F-18 have radars that are both HPRF and Medium PRF (MPRF) and use it in an interleaved manner. The F-16 is MPRF only. MPRF handles aircraft maneuvering VERY well, especially compared to HPRF only.

I have fought them in much smaller scale fights, and the results where decidedly lopsided. In one of my squadrons we were not allowed to do check rides with them as the adversary. I have fought them in BFM, with both the original and GE motors. The GE powered version could be work in a slow speed fight, but not insurmountable. The original engines were way too small for that airframe. Wings pop out at a certain speed, it's limited to 7Gs, it has two people in it, it's huge, and it's over hyped. Look at it's thrust to weight, and compare that to any radar equipped fighter that came out of the US or Russia starting in 1974 (F15, F16, F18, MiG-29, Su-27) and note that none of them, or anything made since, have wings that swing or HPRF only. It was technologically advanced for late 60's, early 70's. After about 1974, not so much.

And the classified summary of its short comings was long as well.

However, it did do some good work once they hung bombs on them.

As was written earlier, the stories are large and written at a time when no one countered them (because we didn't want anyone to really know how bad it was). Get a group of non Tomcat fighter pilots together, and ask them which fighter was the least threatening, and the answer will be the F-14. 

Cheers,
Biff

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## ThomasP (Jun 7, 2021)

Hey BiffF15,

Did you ever get to play with the F-14D? The reason I ask is due to the radar being replaced with the APG-71, and the upgraded JTIDS system. I realize that the engines still did not raise the T/W ratio much past 1:1 at dogfight weights, but I believe the radar upgrade included all the bells and whistles that the APG-71 had, plus a few unique to the F-14D. I also wonder how much help the improved IRST would be.

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## Shortround6 (Jun 7, 2021)

The SBD is a bit over rated, not in what it did, which is beyond dispute, but in some of the "book" figures which crop up all too frequently.

The often quoted 2250 lb bomb load consisted of a 1600lb AP bomb, which so far nobody can find a record of the SBD dropping in action, and two 325lb depth charges, which is certainly an odd combination. It also would have meant an operational radius a tiny bit more than the visual horizon. A US Navy data sheet lists the SBD-5 as holding 254 gallons with a 1000lb bomb and 165 gallons with the 1600lb bomb. Yes, lots of Navy documents list the 1600lb but actual use??
Now unless you exceed max gross weight hanging those 325lb depth charges under the wings calls for leaving 108 gallons of fuel out out of the tanks from that 165. 
*53 gallons* to take off, fly to target, climb to bombing height on the way, execute dive and run for home????????

Makes the P-PTMNBN (Plane That Must Not Be Named) look long ranged  

The Use of the SBD as a "fighter" needs to be looked at also. Yes it was used, but for how long or how many times? 
Was it ever used after the Battle of Coral Sea? I don't believe it was used as a CAP during Midway or after? I could be wrong.

it is a nice little factoid but doesn't really reflect the capabilities or use of the plane over the vast majority of the war.

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## BiffF15 (Jun 7, 2021)

ThomasP said:


> Hey BiffF15,
> 
> Did you ever get to play with the F-14D? The reason I ask is due to the radar being replaced with the APG-71, and the upgraded JTIDS system. I realize that the engines still did not raise the T/W ratio much past 1:1 at dogfight weights, but I believe the radar upgrade included all the bells and whistles that the APG-71 had, plus a few unique to the F-14D. I also wonder how much help the improved IRST would be.



Thomas,

I never fought them, as they were a West Coast based asset (and less than 60 made). The APG-71 as far as I remember, was HPRF only. I read online that it was both HPRF and LPRF (not sure if Low actually means Medium or not). I don't think they were ever equipped with AIM-120's either. As for the GE engines, they were the same in the D as well as the B (or A+) IIRC. As for the JTIDS (Joint Tactical Information Distribution System), it's the Cats Meow. I flew with a detuned version of it in the Eagle, called FDL (Fighter Data Link). The Eagle was originally scheduled to get JTIDS (and one squadron did), it was subsequently replaced with a less expensive and slightly less capable FDL. I can't comment about the IRSTS as I did not fight them.

From what I remember it didn't have all the capabilities that the APG-70 had from the get go, which is a shame (they should have paid for it). The APG-70 was a large leap over the APG-63 (both original and MSIP or Programable Signal Processor versions). The APG-63V1 was new boxes, same old radar dish. The APG-63V2 was the first Eagle to fly with an AESA (Active Electronically Scanned Array), and the APG-63V3 was a much improved AESA over the V2. Those latter radars (V1, 2, & 3) are eye watering in capability. EYE WATERING.

Once the Eagle started flying with AESA radars was the first time to my knowledge that we had Red Flags where no blue air was lost to red air. And that is unbelievably HUGE.

Cheers,
Biff

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## Admiral Beez (Jun 7, 2021)

Thoughts on a thin wing Hurricane?


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## VA5124 (Jun 7, 2021)

Admiral Beez said:


> Thoughts on a thin wing Hurricane?


how thin ?


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## GrauGeist (Jun 7, 2021)

Shortround6 said:


> Was it ever used after the Battle of Coral Sea? I don't believe it was used as a CAP during Midway or after? I could be wrong.



During the battle of Midway, Yorktown's SBDs were used as CAP while the F4Fs were vectored out to intercept the inbound force from Hiryu.

While not a gun-slinger, the SBD did, on several occasions, prove it's worth as supplemental CAP by intercepting B5Ns and D3As.


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## VA5124 (Jun 7, 2021)

i saw a story somewhere where a group of sbds went toe to toe with zeros and lived


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## Greg Boeser (Jun 7, 2021)

It was a SBD rear gunner who put Saburo Sakai out of action for quite a while.


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## Shortround6 (Jun 7, 2021)

Admiral Beez said:


> Thoughts on a thin wing Hurricane?


Gone over it before.





Fuel tanks between front and back spars. Landing gear fits, mostly in the fuselage/wing center section. 





You might be able to use thinner outer wings but that may not give the desired improvement. Making the center section (out to the landing gear attachment points) thinner may have required too much work/rework. Plane would no longer be a Hurricane.

Hurricane was practically a STOL machine once it got the constant speed prop. It could be at 50ft above the runway hundreds of feet before most US army fighters even got the wheels of the ground. Would the extra speed of the thin wing make up for the greater take-off and landing distances (fewer airfields to use? )

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## Shortround6 (Jun 7, 2021)

Greg Boeser said:


> It was a SBD rear gunner who put Saburo Sakai out of action for quite a while.


 And one Avro Anson "claimed" three bf 109s in one fight. doesn't mean the British thought Avro Ansons were the answer to the Bf 109 

The SBD's reputation as a "fighter" seems to be based on a small number of incidents.

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## wuzak (Jun 7, 2021)

Zipper730 said:


> What advantages come with direct injection vs. the pressure carburetor?



I'd guess better metering of fuel to each cylinder.

Incidentally why later R-3350s went to direct fuel injection - poor mixture distribution in earlier models.




Zipper730 said:


> I'm guessing having an X-cylinder with 2-sets of 60-degrees between them top and bottom would be more difficult to pull off?



No more than any X-engine, though balancing could be an issue.




Zipper730 said:


> What's a master and slave type rod, and what would make it weaker than the twin-crankshafts of the X-3420?



Master and Slave rods are what is used by radials. It was also used, on occasion, on in-line engines. The Rolls-Royce R in 1929 ran with fork and blade rods, like the Buzzard it was based on, but the 1931 version was converted to master and slave rods because of big end bearing failures.

The master rod is connected to the crankshaft. The master rods are connected to the master rod.

Master and Slave Rod





Fork and Blade Rods






From Connecting rod - Wikipedia

Not sure if you can say that one is stronger than the other. There are downsides to both.

The twin crank solution adds weight, and requires gears to join the crankshafts together, but simplified other parts of the engine, such as using the same blocks, heads and intake manifolds as the base Vee engine.

The downside to master and slave rods is that the pistons don't have the same stroke, so extra tuning may be required.

The Vulture had master and slave rods, with the big end bearing on the master rod causing a lot of problems, probably the last major issue the Vulture had to be solved at the time of its cancellation.




Zipper730 said:


> How much earlier would you have guessed?



How early would the Army have fully committed to the V-3420? That is the real question, since Allison was not big enough or willing to develop engines without the prospect of sales.

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## Shortround6 (Jun 7, 2021)

wuzak said:


> How early would the Army have fully committed to the V-3420? That is the real question, since Allison was not big enough or willing to develop engines without the prospect of sales.


Quite correct .

The Army, at one point in 1939 owed Allison something like 900,000 dollars for work already done. They never paid it.

In order to get permission to build the Export engines for the French and British P-40 orders (Hawk 81) Allison had to agree to forgive the debt.

Allison at some point in 1939 had a grand total of 25 people working in the engineering section and that include two guys that ran the blueprint machine. 

any and all suggestions that Allison "JUST" do such and such need to be looked at in that light. 

GM had loaned (put in ) over 1/2 million dollars into the V-1710 program and had not the Army ordered the engines for the 524 P-40s in April of 1939 GM was considering shutting down the program. 

Allison was running a highly successful bearing manufacturing operation. many people do not understand how massive the build up of some American companies was.

year..........................end of year employees
1937........................322
1938........................530
1939........................786
1940......................4,303
1941.....................9,763
1942..................14,323
1943..................23,019

Number of employees includes the Bearing division. 

There is reason to believe that Allison could not have done what it did as far as building the engines it did build if it had spent much more time on side projects or not built the engine in a somewhat modular fashion.

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## XBe02Drvr (Jun 7, 2021)

Greg Boeser said:


> It was a SBD rear gunner who put Saburo Sakai out of action for quite a while.


Actually, according to Sakai's own book (with Caudin), it was the rear gunners of a flight of TBFs that did the deed. Spotted from a distance through his soda pop encrusted canopy, he mistook them for F4Fs and raced in to bounce their six. OOOPS! Popping a soda bottle cap at 20,000 feet has certain undesirable effects.


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## Admiral Beez (Jun 7, 2021)

VA5124 said:


> how thin ?


I need to defer to the more aeronautically informed, but this site has some info, The Incomplete Guide to Airfoil Usage


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## wuzak (Jun 7, 2021)

Shortround6 said:


> There is reason to believe that Allison could not have done what it did as far as building the engines it did build if it had spent much more time on side projects or not built the engine in a somewhat modular fashion.



I don't think that the modularity was a problem.

But having to do the base engine (with the long nose, C series engines) plus remote gearbox drives (D series engines) for pusher aircraft (YFM), remote gearbox (E series engines)for tractor aircraft (P-39), opposite hand engines (for P-38), plus the fuel injection project and X-3420/V-3420 work must have put a lot of strain on the small design team, and slowed the development of the core engine. And all this before they got substantial orders from the Army.


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## GrauGeist (Jun 7, 2021)

In Sakai's memoirs (Samurai In The Big Sky), he stated that they were SBDs (which he realized at the last moment during his attack).
It was an SBD of VS-6, piloted by Ens. Shaw, on a bombing mission at Tulagi that Sakai attacked. The rear gunner, Harold Jones lit him up at point-blank range with his twin .30MGs.

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## Thumpalumpacus (Jun 8, 2021)

VA5124 said:


> if you would bulid it like i said it would have been better



Putting more engines on a dive-bomber increases the practical weight of the aircraft as it pulls out of the dive. A 2-G pullout doubles the weight the airframes thinks it is, and you have to structure for that.

Now put those engines out on the wings -- which is more weight in and of itself -- and then add in the extra weight for the load-bearing members to keep the wings from flying off due to the extra leverage the weight location adds, and you end up with something that might drop a good load, but cannot go too steep, and has its level-flight performance impaired dragging around all that reinforcement. Of course, if the dive is accurate enough it can still perhaps crash into the target.

It's about trade-offs. It's why you didn't see too many twin-engined dive-bombers.


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## VA5124 (Jun 8, 2021)

you need more enigiesm just a supercharing systhem


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## GrauGeist (Jun 8, 2021)

VA5124 said:


> you need more enigiesm just a supercharing systhem


The Stuka had a supercharged engine.
The SBD had a supercharged engine.

Perhaps you'd be happy to know the Heinkel He177 was "dive bomb capable" and could carry about 15,000 pounds of bombs and it had four supercharged engines (two DB610s).
Or if you're wanting fast, there was the Henschel He132 jet dive-bomber, but it couldn't carry 4,000 pounds and it didn't have a supercharger...


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## VA5124 (Jun 8, 2021)

change the wright for a pratt and then supercharge it


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## GrauGeist (Jun 8, 2021)

VA5124 said:


> change the wright for a pratt and then supercharge it


Um...hello?

The SBD's engine WAS supercharged...


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## VA5124 (Jun 8, 2021)

but it was a 9 cyl wright that made no power change it to a 14 or 18 cyl pratt renfoce the wings to increase the bomb load switch the .50s in the wings for 20s swich the tiwn 30 in the rear for a twin .50 and make the landing gear stronger to handle the speed and weight


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## Greg Boeser (Jun 8, 2021)

VA5124 said:


> i saw a story somewhere where a group of sbds went toe to toe with zeros and lived


Check out John Lundstrom's _First Team_ and _First Team at Guadalcanal, _two excellent books about the USN carrier operations during 1942. Although he focuses on the fighter pilots, he also covers the activities of the other carrier based aircraft, as well as the activities of the Japanese. He relies on both US and Japanese records, as well as interviews with pilots from both sides. His analysis shreds many popular myths.

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## GrauGeist (Jun 8, 2021)

Why not put rocket engines on the wings with phase-cannons in each wing?

I suspect it could carry at least two photon torpedoes, not sure of the weight of each.

Then again, an Imperial TIE/LN might be able to intercept it if it carried more than two - I'm speculating here, though.

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## VA5124 (Jun 8, 2021)

i dont know anything about star wars but im serious about the changes i metionsed


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## GrauGeist (Jun 8, 2021)

VA5124 said:


> i dont know anything about star wars but im serious about the changes i metionsed


Your changes are about as realistic as Star Trek and Star Wars combined.

In a fantasy universe, you can stuff a turbo-supercharged engine In anything you want, then add 8,000 pounds of bombs and 12.machine guns and go kill Nazis.

In this universe, we have what's called "laws of physics".
This is why the SBD didn't have monster engines and the Corsair didn't have jets...

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## VA5124 (Jun 8, 2021)

it would be called the douglas demon


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## GrauGeist (Jun 8, 2021)

VA5124 said:


> it would be called the douglas demon


And then the Imperial Japanese would use their Shōki (Demon Queller) to snuff it.

Now what?


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## VA5124 (Jun 8, 2021)

japan wouldnt have a chance againist the sbd-6 aka the douglas demon


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## Greg Boeser (Jun 8, 2021)

VA5124 said:


> but it was a 9 cyl wright that made no power change it to a 14 or 18 cyl pratt renfoce the wings to increase the bomb load switch the .50s in the wings for 20s swich the tiwn 30 in the rear for a twin .50 and make the landing gear stronger to handle the speed and weight


Dude! I'm telling you! AD-1 Skyraider!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
First flight: March 18 1945
Wright Duplex-Cyclone R3350 (Sorry, not a Pratt)
No rear gunner either, but a pair of 20mm in the wings
Could carry more bombs than a B-17

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## VA5124 (Jun 8, 2021)

Greg Boeser said:


> Dude! I'm telling you! AD-1 Skyraider!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> First flight: March 18 1945
> Wright Duplex-Cyclone R3350 (Sorry, not a Pratt)
> No rear gunner either, but a pair of 20mm in the wings
> Could carry more bombs than a B-17


 the ad 1 came too late to see sercive in ww2 thats why i suggested buliding the douglas demon


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## GrauGeist (Jun 8, 2021)

VA5124 said:


> japan wouldnt have a chance againist the sbd-6 aka the douglas demon


The KI-201 Karyu would destroy it.


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## VA5124 (Jun 8, 2021)

if they got it bulit before the war ended which according to wiki the prototype was never bulit leaving the douglas demon to rain suprame


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## GrauGeist (Jun 8, 2021)

VA5124 said:


> if they got it bulit before the war ended which according to wiki the prototype was never bulit leaving the douglas demon to rain suprame


Um...but your "demon" doesn't exist, the KI-201 prototype actually did, so the Japanese win by default.

Next...


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## VA5124 (Jun 8, 2021)

this thread said improve the design which i did it didnt say anything about it being bulit so i win


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## Greg Boeser (Jun 8, 2021)

But the "Demon" wasn't built at all. And wouldn't be.
The AD-1 _was_ built and was one of the most successful carrier based attack aircraft ever. It was in frontline service for over twenty years in the USN and USAF, and served many more years in reserve components.

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## GrauGeist (Jun 8, 2021)

VA5124 said:


> this thread said improve the design which i did it didnt say anything about it being bulit so i win


Ahh...but you have to PROVE it was a viable improvement under the laws of known physics, not fantasy nonsense.

Otherwise, this is what your "Demon" would be up against:

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## VA5124 (Jun 8, 2021)

Greg Boeser said:


> But the "Demon" wasn't built at all. And wouldn't be.
> The AD-1 _was_ built and was one of the most successful carrier based attack aircraft ever. It was in frontline service for over twenty years in the USN and USAF, and served many more years in reserve components.


 bulid the demon and the skyraider wouldnt have happened


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## Zipper730 (Jun 8, 2021)

wuzak said:


> I'd guess better metering of fuel to each cylinder.


Okay, that makes sense. As for the R-3350's switching to direct-fuel injection, was this during the war?


> No more than any X-engine, though balancing could be an issue.


So, it's preferable to have 90-degrees for an X and 60-degrees for a V?


> Master and Slave rods are what is used by radials. It was also used, on occasion, on in-line engines. The Rolls-Royce R in 1929 ran with fork and blade rods, like the Buzzard it was based on, but the 1931 version was converted to master and slave rods because of big end bearing failures.


So the master rod is the bigger one?


> The twin crank solution adds weight, and requires gears to join the crankshafts together, but simplified other parts of the engine, such as using the same blocks, heads and intake manifolds as the base Vee engine.


I'm confused why the horsepower would be different, you basically have two V-1710's -- one upright, the other upside down. I don't quite grasp why you would have less than twice the horsepower.


> The downside to master and slave rods is that the pistons don't have the same stroke, so extra tuning may be required


Wait, all the pistons don't go up and down the same amount? I thought they were all the same...


> The Vulture had master and slave rods, with the big end bearing on the master rod causing a lot of problems


Why did it cause so many problems?


> How early would the Army have fully committed to the V-3420? That is the real question, since Allison was not big enough or willing to develop engines without the prospect of sales.


The US Army was the one that wanted the engine built. That's what lead Allison to design it. So, that's not the issue.

I can see the following advantages for the W-3420 (as it was): It was lighter, and simpler; and the following disadvantages: It was very wide and would make it difficult to fit in some fighter designs.


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## Zipper730 (Jun 8, 2021)

I remember something being said about medic's having a cross on their helmet, which they said enemy snipers were using to aim at them better. This might have been during the course of the Vietnam war.


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## wuzak (Jun 8, 2021)

Zipper730 said:


> Okay, that makes sense. As for the R-3350's switching to direct-fuel injection, was this during the war?



I believe that happened just before the end of the war.




Zipper730 said:


> So, it's preferable to have 90-degrees for an X and 60-degrees for a V?



I would think that equal spacing of the banks is preferable on an X engine.

Engines with that arrangement include the Rolls-Royce Vulture, Exe, Pennine and Eagle XVI, the Allison X-4520 and the Daimler Benz DB 604. All were X-24s, except for the Eagle XVI, which was an X-16.

The Napier Cub engine of 1919 was an X-16 with the outer pairs of banks separated by 90°, with the upper banks separated by 52.5°.

Both the X-3420 and V-3420 had 60° between the outer banks. So both could share the cylinder blocks, heads, intakes with the V-1710.

The X-3420 had 90° between the upper banks, which meant that the lower banks were 150° apart, and pointing down 15° from the horizontal. This would require adding a system to return the oil to the sump from the cylinder heads/cam covers.

The V-3420 had 90° between the centrelines of the outer banks. Which meant that the upper banks were 30° apart, but also spaced by 12 3/4in separation between the cranlshafts.




Zipper730 said:


> So the master rod is the bigger one?



Yes.




Zipper730 said:


> I'm confused why the horsepower would be different, you basically have two V-1710's -- one upright, the other upside down. I don't quite grasp why you would have less than twice the horsepower.



Allison estimated 1,600hp for the X-3420 and 2,300hp for the V-3420 (ie double what the V-1710 had, or was projected to have, at the time).

Allison did not have much, if any, experience with master and slave rod engines. The X-4520 mentioned above had each pair of banks connected to the crankshaft with fork and blade rods, with one pair of banks offset from the other (the same was the case for the Eagle XVI).

They estimated a maximum of 2,400rpm for the X-3420, which is why the power estimate is lower.




Zipper730 said:


> Wait, all the pistons don't go up and down the same amount? I thought they were all the same...



They can't be with master and slave rods. The master rod is connected to the crankshaft, and the slave rods to it. So the slave rods are shorter and do not centre on the crank pin, so they have different motion from the master rod. This means they either have shorter or longer stroke than the master rod (I can't recall which).

Engines with fork and blade rods have the same stroke across all cylinders.




Zipper730 said:


> Why did it cause so many problems?



The designs they had never did get sufficient clamping force on the bearing for it to work effectively.




Zipper730 said:


> The US Army was the one that wanted the engine built. That's what lead Allison to design it. So, that's not the issue.



They did. And then they didn't. Then they did. And then they didn't.

It also did not help Allison that the Army wanted the engine but did not give firm orders for production models.




Zipper730 said:


> I can see the following advantages for the W-3420 (as it was): It was lighter, and simpler; and the following disadvantages: It was very wide and would make it difficult to fit in some fighter designs.



I don't know why you would think that the V-3420 would be lighter than the X-3420, since it had two crankshafts, which is one of the heaviest components of the engine. The X-3420 was estimated to be 2,160lb against 2,300lb for teh V-3420.

The X-3420 would have been more compact.


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## XBe02Drvr (Jun 8, 2021)

GrauGeist said:


> Or if you're wanting fast, there was the Henschel He132 jet dive-bomber, but it couldn't carry 4,000 pounds and it didn't have a supercharger...


Actually, it HAD a supercharger, just not a piston engine to attach it to. It had a turbine and a compressor, just no crankcase, crankshaft, or cylinders.

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## XBe02Drvr (Jun 8, 2021)

VA5124 said:


> but it was a 9 cyl wright that made no power change it to a 14 or 18 cyl pratt renfoce the wings to increase the bomb load switch the .50s in the wings for 20s swich the tiwn 30 in the rear for a twin .50 and make the landing gear stronger to handle the speed and weight


You know, maybe he's got an idea here. Build a mini Skyraider with an R2800, and cancel the the Curtiss Widowmak(oops, I meant)Helldiver. Engine's already supercharged, no turbo needed, he's got his precious 20s, what's not to like? With an R2800, it could probably carry a B17-over-Regensberg size bombload.


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## Shortround6 (Jun 8, 2021)

VA5124 said:


> japan wouldnt have a chance againist the sbd-6 aka the douglas demon



1. There was an SBD-6, 450 built near the end of WW II. The nine cylinder Wright cyclone gave 1350hp in this version. 
2. The engine in the real SBD-6 weighed 1333lbs.
3. The engine in the SBD-3 weighed 1315lbs. 
4. The P & W R-2800 as used in the F4U weighed 2480lbs and needed a much bigger propeller than the engine used in the SBD. 
4. The engine used in the Skyraider AD-1 weighed 2822lbs. Also a much bigger prop. 

You can build or imagine hypothetical aircraft. They just have to follow the actual laws of physics. It helps a lot if they follow actual history, like not using 1945 engines in 1942. 

You might want to consider the need to actually get a hypothetical plane on and off an aircraft carrier if a naval plane. For take off distance the worst US Navy fighter on land used hundreds of feet less runway than the Best US Army fighter.

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## Shortround6 (Jun 8, 2021)

XBe02Drvr said:


> You know, maybe he's got an idea here. Build a mini Skyraider with an R2800, and cancel the the Curtiss Widowmak(oops, I meant)Helldiver. Engine's already supercharged, no turbo needed, he's got his precious 20s, what's not to like? With an R2800, it could probably carry a B17-over-Regensberg size bombload.







Not a dive bomber but an R-2800 powered torpedo bomber. Consolidated Seawolf, originally designed by Vought but taken over by Consolidated due to lack of production capacity by Vought. Consolidated did have to build a new factory which delayed things.


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## wuzak (Jun 8, 2021)

XBe02Drvr said:


> You know, maybe he's got an idea here. Build a mini Skyraider with an R2800, and cancel the the Curtiss Widowmak(oops, I meant)Helldiver. Engine's already supercharged, no turbo needed, he's got his precious 20s, what's not to like? With an R2800, it could probably carry a B17-over-Regensberg size bombload.





Shortround6 said:


> View attachment 626662
> 
> Not a dive bomber but an R-2800 powered torpedo bomber. Consolidated Seawolf, originally designed by Vought but taken over by Consolidated due to lack of production capacity by Vought. Consolidated did have to build a new factory which delayed things.



Only 2,000lb bomb load. Not quite a "B17-over-Regensberg size bombload" (ie 5,000lb).


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## Shortround6 (Jun 8, 2021)

wuzak said:


> Only 2,000lb bomb load. Not quite a "B17-over-Regensberg size bombload" (ie 5,000lb).


Yes but the B17-over-Regensberg size bombload when carried by a single engine plane is at a very short distance. 

Could carry four torpedoes with a radius of 215 miles.
Weighed more than an A-20G and even more than an early B-26 at normal gross weight. 
Also needed Midway class carrier


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## XBe02Drvr (Jun 8, 2021)

wuzak said:


> Only 2,000lb bomb load. Not quite a "B17-over-Regensberg size bombload" (ie 5,000lb).


Also, a lot more airplane than is needed for the job. I suggested a mini Skyraider, not a re-engined Fairey Barracuda. An Ed Heineman minimalist approach called for here.

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## XBe02Drvr (Jun 8, 2021)

wuzak said:


> They can't be with master and slave rods. The master rod is connected to the crankshaft, and the slave rods to it. So the slave rods are shorter and do not centre on the crank pin, so they have different motion from the master rod. This means they either have shorter or longer stroke than the master rod (I can't recall which).


IIRC, the radials we tore down and rebuilt in mech school had slave conrods individually sized for their position on the master rod. Our instructor said that was an attempt to keep compression ratios constant across all cylinders.


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## Zipper730 (Jun 9, 2021)

*Regarding Allison Engines*



Shortround6 said:


> There is reason to believe that Allison could not have done what it did as far as building the engines it did build if it had spent much more time on side projects or not built the engine in a somewhat modular fashion.


The numbers of people available makes it easy to understand why they would have had so much difficulty with the V-1710-59's supercharger.

*Regarding the X-3420/V-3420*



wuzak said:


> I believe that happened just before the end of the war.


So, there were some B-29 variants flying around with those in them?


> I would think that equal spacing of the banks is preferable on an X engine.


It definitely produces good symmetry.


> Engines with that arrangement include the Rolls-Royce Vulture, Exe, Pennine and Eagle XVI, the Allison X-4520 and the Daimler Benz DB 604. All were X-24s, except for the Eagle XVI, which was an X-16.


But 90-degrees would have made the engine radically different from the V-1710?

Regarding the X-4520, I'm amazed with so many rows of cylinders (one behind the other) that they managed to employ a successful cooling system (unless they blew the cooling-air in with sufficient force to carry away the heat as fast as it came up) -- the R-4360 had a hard time with four rows, and they were offset from each other.


> Both the X-3420 and V-3420 had 60° between the outer banks. So both could share the cylinder blocks, heads, intakes with the V-1710.


So each bank would be turned on it's side not one bank upper, one bank lower for the X-3420?


> Allison estimated 1,600hp for the X-3420 and 2,300hp for the V-3420 (ie double what the V-1710 had, or was projected to have, at the time).


And this was due to the lower RPM estimated, and this was due to the inexperience with master/slave rods. I'm guessing once they committed to 2400 RPM, it would take serious work to raise it up to 3000 RPM like the V-1710?


> They can't be with master and slave rods.


I guess fork/blades couldn't handle the forces?


> The designs they had never did get sufficient clamping force on the bearing for it to work effectively.


Would this be a problem with the X-3420?


> I don't know why you would think that the V-3420 would be lighter than the X-3420, since it had two crankshafts, which is one of the heaviest components of the engine. The X-3420 was estimated to be 2,160lb against 2,300lb for teh V-3420.


That is interesting.


> The X-3420 would have been more compact.


Because of the lack of two shafts?


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## wuzak (Jun 10, 2021)

Zipper730 said:


> *Regarding the X-3420/V-3420*
> 
> So, there were some B-29 variants flying around with those in them?



If you mean fuel injected R-3350s, then probably there were a few by the end of the war. Someone else may have more details.


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## wuzak (Jun 10, 2021)

Zipper730 said:


> *Regarding the X-3420/V-3420*
> But 90-degrees would have made the engine radically different from the V-1710?



The intakes would not have fitted. And two cylinder heads and/or rocker covers would have to be redesigned to allow for the oil to be scavenged back to the oil tank.




Zipper730 said:


> Regarding the X-4520, I'm amazed with so many rows of cylinders (one behind the other) that they managed to employ a successful cooling system (unless they blew the cooling-air in with sufficient force to carry away the heat as fast as it came up) -- the R-4360 had a hard time with four rows, and they were offset from each other.



4 banks of 6 cylinders.

Not dissimilar to air cooled V-12s, such as the de Havilland Gipsy Major/Twelve. 

Or for the Napier Dagger - 4 banks of 6 air cooled cylinders mounted in a H style engine (with 2 crankshafts).

I think the offset of the R-4360 made it harder to get cooling right than for an air cooled inline - where the cooling air could be fed into a plenum between the cylinders and forced outwards, or vice versa.




Zipper730 said:


> So each bank would be turned on it's side not one bank upper, one bank lower for the X-3420?



If 0° is vertically upwards from the crank centreline, the X-3420 would have cylinder banks at -105°, -45°, 45° and 105°. The outer two banks were angled below the horizontal (which would be +/-90°).

The V-3420 had cylinder banks at -75°, -15°, +15°, +75°. The outer banks were above horizontal.

I don't know what you mean by "turned on its side".




Zipper730 said:


> And this was due to the lower RPM estimated, and this was due to the inexperience with master/slave rods. I'm guessing once they committed to 2400 RPM, it would take serious work to raise it up to 3000 RPM like the V-1710?



I honestly do not know where they came up with 2,400rpm. Maybe it was the speed of 7 or 9 cylinder radials of the time (1937). 

Though, Rolls-Royce were just starting to run the Vulture and would soon run it to its maximum speed of 3,200rpm. The Vulture did have a 5.5 inch stroke, compared to the 6 inch stroke of the V-1710 family.




Zipper730 said:


> I guess fork/blades couldn't handle the forces?



Fork and blade rods could really handle more than 2 cylinders. To run 4 cylinders on a single crankshaft would require two sets of fork and blade rods, side by side. This means that two cylinder banks would be offset along the crankshaft axis with respect to the other banks. 

This is actually what the Allison X-4520 did, as was also the case for the Eagle XVI, which was only built as a test engine, and was not flight cleared.

This lengthens the engine, even if not by a lot.

The bigger issue using side by side fork and blade rods was that the crank pin would have to be longer and thus the bore spacing would need to grow.

The crankshaft pins, obviously, were at the same spacing as the bores. And the crankshaft pins had enough room for one set of fork and blade rods. Needing a second set would double the length of the pin.




Zipper730 said:


> Would this be a problem with the X-3420?



Possibly. The angles were different, so they may have been able to find a more suitable clamping solution.

Note that had the Vulture continued Rolls-Royce may have gone for the fork and blade rod solution. The Vulture had a 5 inch bore, like the Peregrine, but a bore spacing almost a half inch longer.

Also note that the later Rolls-Royce Pennine X-24 used single piece master rods and a multiple piece crankshaft, similar to the practice adopted for many radials (like the R-2800).

Pergelator: Master Connecting Rod




Zipper730 said:


> Because of the lack of two shafts?



Yes, and that the two crankshafts were 12 3/4 inches apart.

The X-3420 would have been 12 3/4 inches narrower.


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## Zipper730 (Jun 15, 2021)

I'm not sure if this was covered before, but what prevented the Consolidated B-32's pressurization system from working?

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## Niceoldguy58 (Jul 25, 2021)

Due to the position of the spar, the diameter of the fuselage was too narrow to accept a "tunnel" from the front pressurized compartment to the back. In order to accommodate one the fuselage diameter would have had to increase by about two more feet or so IIRC. I have copies of the original drawings showing this.

AlanG

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## MIflyer (Jul 25, 2021)

They proposed to use the B-32 as gunships for the invasion of Japan. A friend of mine trained as a gunner for them and was told they would fly low and strafe targets for the invasion of Japan. Some people say this is absurd but they had already been doing that with B-25's in Burma and the distance from Okinawa to the Japanese mainland was a bit far for medium bombers. And for that they did not need pressurization anyway.

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## SaparotRob (Jul 25, 2021)

GrauGeist said:


> Ahh...but you have to PROVE it was a viable improvement under the laws of known physics, not fantasy nonsense.
> 
> Otherwise, this is what your "Demon" would be up against:
> View attachment 626590


How did I miss this post?

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## Zipper730 (Jul 25, 2021)

Niceoldguy58 said:


> Due to the position of the spar, the diameter of the fuselage was too narrow to accept a "tunnel" from the front pressurized compartment to the back. In order to accommodate one the fuselage diameter would have had to increase by about two more feet or so IIRC. I have copies of the original drawings showing this.


Sounds like a major design flaw.


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## 33k in the air (Jul 25, 2021)

MIflyer said:


> They proposed to use the B-32 as gunships for the invasion of Japan. A friend of mine trained as a gunner for them and was told they would fly low and strafe targets for the invasion of Japan. Some people say this is absurd but they had already been doing that with B-25's in Burma and the distance from Okinawa to the Japanese mainland was a bit far for medium bombers. And for that they did not need pressurization anyway.



Seems like a waste of materiel.

The B-32 could carry the same bomb load as the B-29, and had a range that was not that much shorter (compared to the B-29s with the center tank). The big difference is the lack of pressurization and remote-controlled turrets.

I would have thought adding to the bomb dropping striking power would be a better use of the aircraft.

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## GrauGeist (Jul 25, 2021)

33k in the air said:


> Seems like a waste of materiel.
> 
> The B-32 could carry the same bomb load as the B-29, and had a range that was not that much shorter (compared to the B-29s with the center tank). The big difference is the lack of pressurization and remote-controlled turrets.
> 
> I would have thought adding to the bomb dropping striking power would be a better use of the aircraft.


They already had fleets of B-24s, B-17s and B-29s - what was lacking was a long range ground attack platform.

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## 33k in the air (Jul 26, 2021)

GrauGeist said:


> They already had fleets of B-24s, B-17s and B-29s - what was lacking was a long range ground attack platform.



A four-engine very heavy bomber seems like a poor choice and a rather large bullet magnet. Up to 40 x 500-lb bombs in one aircraft seems a more effective attack.

(Tiger Force, the collection of RAF and RCAF Lancaster squadrons, would have also been available had the war dragged on.)


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## GrauGeist (Jul 26, 2021)

But medium bombers didn't have the range from Okinawa and the B-32s that did see action were used mainly as recon including being some of the last Allied aircraft to engage Japanese elements at war's end.
So great, we have a massive fleet of bombers but no flak suppression or close air support - what now?

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## MIflyer (Jul 26, 2021)

GrauGeist said:


> but no flak suppression or close air support - what now?



Exactly! And the experience of the rest of the Pacific showed that we could expect human wave attacks. BANZI! Everything from toddlers to the elderly charging with hoes, rakes, and butter knives. The fighters needed drop tanks to even get to Japan, even from Okinawa, and thus would have only had their .50 cal guns, and limited loiter time.

As for 500 lb bombs, where are you going to drop them when you have troops in close contact? I wonder if they ever hit on the idea of dropping flares for night attacks? They probably would have gotten there

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## Thumpalumpacus (Jul 26, 2021)

GrauGeist said:


> But medium bombers didn't have the range from Okinawa and the B-32s that did see action were used mainly as recon including being some of the last Allied aircraft to engage Japanese elements at war's end.
> So great, we have a massive fleet of bombers but no flak suppression or close air support - what now?



Coordinate with CAGs. By 1945 the four main types flying off carrier decks could carry rockets as well as bombs, and would be much more survivable, being smaller, faster, and more maneuverable, right?

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## drgondog (Jul 26, 2021)

Zipper730 said:


> Sounds like a major design flaw.


Why? Its operating altitude was much lower than B-29 and B-29 ops from March 1945 to EOW showed that high altitude ops were less effective over Japan than traditional ETO ops.

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## drgondog (Jul 26, 2021)

Thumpalumpacus said:


> Coordinate with CAGs. By 1945 the four main types flying off carrier decks could carry rockets as well as bombs, and would be much more survivable, being smaller, faster, and more maneuverable, right?


they don't fly very far w/o combat tanks, meaning that the Carriers were very close to inbound Kamikaze strikes.

IIRC neither F4U nor F6F could carry 2x500 pound bombs 100 miles for a mission - so for longer missions they would escort the other two types.

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## GrauGeist (Jul 26, 2021)

Thumpalumpacus said:


> Coordinate with CAGs. By 1945 the four main types flying off carrier decks could carry rockets as well as bombs, and would be much more survivable, being smaller, faster, and more maneuverable, right?


As the Allied fleet approached Okinawa, they came under savage air attack, both conventional and by Kamikaze, resulting in considerable damage and loss.
The Japanese air elements were not only coming from Okinawa, but bases on the southern home island of Kyushu 500 miles to the north.
For the invasion of the home islands, the Allied fleet would come under the gauntlet of the same, but intensified attacks.
So pre-invasion bombing/ground attack missions would be a must and it would be up to the long range air elements from Okinawa to lead the way and scour every square inch of soil, leaving no stone unturned.

Operation Downfall and all it involved would have made Operation Overlord look like a Sunday outing at the beach.

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## Admiral Beez (Jul 26, 2021)

tomo pauk said:


> Once could argue that Skua was far more streamlined than Ju-87 or Aichi Val - retractable U/C vs. fixed, and no 'dropped' flaps like the Ju 87 had. Where it lacked was 'under the hood', 900 HP is not going to enable much more than it was historically so.


If we can get a 1,000 bomb onto the Skua's cradle whilst keeping its steep dive angle we can, IMO forgive the rest. For starters the FAA needs to source a 1,000 lb. APHE bomb, since the RAF's usual 1,000 lb GP bomb won't do the job. General-purpose bomb - Wikipedia Perhaps some of the old stock of 12" shells could be modified, though they didn't do well at Jutland.


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## SaparotRob (Jul 26, 2021)

A 14" version did do considerable damage to U.S.S. Arizona. Perhaps it might've worked against targets with thinner deck armor?


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## Shortround6 (Jul 26, 2021)

Germans only had 4 ships that would require a 1000lb SAP bomb. Italians only had 3-5?
However the British 500lb SAP was neither fish nor fowl. Not enough penetration for the big ships and too much for small ones. Not enough explosive for either.

Put 1 or 2 1000lb HE bombs into the upper works of most cruisers and battleships and you have a mission kill at the least. Months in dockyard.


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## Admiral Beez (Jul 26, 2021)

SaparotRob said:


> A 14" version did do considerable damage to U.S.S. Arizona. Perhaps it might've worked against targets with thinner deck armor?


The RN likely has a lot of 13.5" shells in stockyards someplace. Maybe that's our APHE of choice.

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## fastmongrel (Jul 26, 2021)

The 1,000lb GP bomb didn't exist when the Skua was being designed.

I have measured my 1/72 scale Skua (I know not an engineering drawing) and it looks like a bigger bomb will fit. The bomb recess is 5' 6" long X 2' 2" wide by approx 10" deep. 

The Skua had a 319 sq ft wing area virtually the same as a Dauntless so with a 1200hp engine I can't see any problems.

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## Admiral Beez (Jul 26, 2021)

fastmongrel said:


> The 1,000lb GP bomb didn't exist when the Skua was being designed.


I tried, I really did.


Admiral Beez said:


> For starters the FAA needs to source a 1,000 lb. APHE bomb....


We're going to need to need to source or develop a 1,000 lb. APHE bomb.

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## Kilkenny (Jul 26, 2021)

A6M- Should have been designed around the Kinsei engine from the outset (ala the A6M8 of 1945), with four 12.5mm guns in the wings, two side-by-side self-sealing fuselage gas tanks, armor protection for the pilot, and butterfly flaps. This would have resulted in a much tougher opponent for the Hellcat and Corsair (even if only topping out at 360mph).
J2M- Should have been given priority attention in 1940, so as to be operational in 1942 (instead of 1944). And received a two-stage turbocharger by 1944 at the latest. A first-class, tough interceptor that would have been a tough opponent for high-altitude US bombers.
Ki-67- Should have been given priority attention in 1940, so as to be operational in 1942 (and totally replace all other Army and Navy two-engined bombers, especially the Betty).
Ki-61- Should have been built with the Kinsei engine from the outset (instead of in 1945 as the Ki-106). This fine aircraft would have totally replaced the Ki-43 and would have been a very tough opponent through 1945.
Ki-84- The Homare engine was too difficult to manufacture and service. This plane also should have been built with the MK9 (18-cylinder Kinsei) engine and likely would have been the last piston fighter needed by the Japanese. It would also have a carrier version.
B7M- Should have been given priority attention in 1940, so as to be operational in 1943 (instead of 1945). Would have replaced all existing IJN naval dive and torpedo bombers.
Of course, all the above assumes that Nakajima and Mitsubishi would cooperate and cross-license everything, and the Japanese Army and Naval would also cooperate in aircraft manufacture. Probably asking way too much!

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## GrauGeist (Jul 26, 2021)

Kilkenny said:


> Ki-61- Should have been built with the Kinsei engine from the outset (instead of in 1945 as the Ki-106). This fine aircraft would have totally replaced the Ki-43 and would have been a very tough opponent through 1945.


Do you perhaps mean the KI-100?

The KI-106 was an upgrade prototype (much like the KI-116) of the KI-84.


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## SaparotRob (Jul 26, 2021)

The J2M showing up in 1942 would have posed quite a problem for the Allies as well as the tougher Zero.


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## 33k in the air (Jul 26, 2021)

GrauGeist said:


> But medium bombers didn't have the range from Okinawa and the B-32s that did see action were used mainly as recon including being some of the last Allied aircraft to engage Japanese elements at war's end.
> So great, we have a massive fleet of bombers but no flak suppression or close air support - what now?



But you do have P-51s available to suppress flak. A swarm of small, fast, agile fighters seems a better choice than big, lumbering, very heavy bombers. If guns aren't enough, load the fighters up with HVARs or fragmentation bombs.

Or, get drop tanks and/or auxiliary bomb bay tanks onto the B-25s to extend their range.

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## fastmongrel (Jul 26, 2021)

Admiral Beez said:


> I tried, I really did.
> 
> We're going to need to need to source or develop a 1,000 lb. APHE bomb.


Interesting page about air munitions in the Pacific. It covers US and Japanese AP bombs


The Pacific War Online Encyclopedia: Bombs

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## SaparotRob (Jul 26, 2021)

Nice link!


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## Admiral Beez (Jul 26, 2021)

Made the Me 262 with the intended yet unobtanium metals and you've got a reliable interceptor.

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## GrauGeist (Jul 26, 2021)

33k in the air said:


> But you do have P-51s available to suppress flak. A swarm of small, fast, agile fighters seems a better choice than big, lumbering, very heavy bombers. If guns aren't enough, load the fighters up with HVARs or fragmentation bombs.
> 
> Or, get drop tanks and/or auxiliary bomb bay tanks onto the B-25s to extend their range.


Odd...we can send in bombers with escort and we can send in fighters in ground attack. We can even send in B-25s but we can't send in a B-32.

Is there something different about the B-32 that sets it aside from the B-17, B-24, B-25 and B-29 that I'm not aware of?


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## 33k in the air (Jul 26, 2021)

GrauGeist said:


> Is there something different about the B-32 that sets it aside from the B-17, B-24, B-25 and B-29 that I'm not aware of?



It's much bigger and far less maneuverable than twin-engine mediums or single-engine fighters? There's also not a lot of them. Saturating a target with many attackers helps split up the defender's fire.

If you could turn the B-32 into a stand-off gun platform like the AC-130 gunship, that might be well worth it. (Not sure if the technology of the time could support the concept, though.)


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## swampyankee (Jul 26, 2021)

GrauGeist said:


> Odd...we can send in bombers with escort and we can send in fighters in ground attack. We can even send in B-25s but we can't send in a B-32.
> 
> Is there something different about the B-32 that sets it aside from the B-17, B-24, B-25 and B-29 that I'm not aware of?


It's what you're positing it being used for. Something like bombardment or minelaying (something B-29s did to quite significant, albeit largely unheralded, result) would be perfectly reasonable. Strafing would not be, especially as carrier-based and land-based fighters and attack aircraft were quite capable of doing so, and both actually did attack land targets in Japan's home islands.


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## GrauGeist (Jul 26, 2021)

The B-32 conducted photo recon missions over the home islands and fared well.

For contrast, the B-25 was close to 100 miles an hour slower than the B-32 (which was rated at 330mph at 10,000 feet with a bombload) and I'm fairly sure that if the B-32 were to be used in a ground attack role, it would be accompanied by fighter escort.

Considering the armament layout of the B-25 and A-26 gunships, it would have been interesting to see the B-32 gunship proposal layout.

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## Greg Boeser (Jul 26, 2021)

33k in the air said:


> But you do have P-51s available to suppress flak. A swarm of small, fast, agile fighters seems a better choice than big, lumbering, very heavy bombers. If guns aren't enough, load the fighters up with HVARs or fragmentation bombs.
> 
> Or, get drop tanks and/or auxiliary bomb bay tanks onto the B-25s to extend their range.


The B-25s flying out of the Aleutians were doing just that.


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## Thumpalumpacus (Jul 26, 2021)

GrauGeist said:


> As the Allied fleet approached Okinawa, they came under savage air attack, both conventional and by Kamikaze, resulting in considerable damage and loss.
> The Japanese air elements were not only coming from Okinawa, but bases on the southern home island of Kyushu 500 miles to the north.
> For the invasion of the home islands, the Allied fleet would come under the gauntlet of the same, but intensified attacks.
> So pre-invasion bombing/ground attack missions would be a must and it would be up to the long range air elements from Okinawa to lead the way and scour every square inch of soil, leaving no stone unturned.
> ...



Agreed, I wasn't trying to say it'd be anything near a picnic. But I agree with 

 33k in the air
, that big, low, and slow would add to the casualty rolls without adding much combat capability. Wasn't this the same reasoning behind not using the A-26 much in ground support in ETO?


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## GrauGeist (Jul 26, 2021)

Thumpalumpacus said:


> Agreed, I wasn't trying to say it'd be anything near a picnic. But I agree with
> 
> 33k in the air
> , that big, low, and slow would add to the casualty rolls without adding much combat capability. Wasn't this the same reasoning behind not using the A-26 much in ground support in ETO?


Again, the B-32 was one of the fastest bombers for it's size of that time.
It was faster than the B-25 and B-26 and it's speed was comparable to the A-26.

The A-20, A-26, B-25 and P-61 all conducted ground attack in the ETO.

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## Thumpalumpacus (Jul 26, 2021)

But at what altitudes? And is it maneuverable enough to line up an low-level attack run? Or are we talking medium-level bombing?


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## GrauGeist (Jul 26, 2021)

Thumpalumpacus said:


> But at what altitudes? And is it maneuverable enough to line up an low-level attack run? Or are we talking medium-level bombing?


It was proposed to make the B-32 a gunship (strafer) like the A-20, B-25 and A-26s were.

And like the strafers, it would make a hot pass, hosing anything in it's path.

I'm simply playing Devil's advocate here, the idea of a monster gunship intrigues me and when I first heard the idea, it occurred to me that the B-32, of all the heavy bombers made, could actually pull it off.
Also, considering the B-25s and A-26s had over a dozen foreward-firing .50MGs (even a few cases of up to eighteen), I tried to imagine just how many .50s (or 20mm, like the P-61) could be applied. Especially since it would not be carrying bombs.

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## Thumpalumpacus (Jul 26, 2021)

GrauGeist said:


> It was proposed to make the B-32 a gunship (strafer) like the A-20, B-25 and A-26s were.
> 
> And like the strafers, it would make a hot pass, hosing anything in it's path.
> 
> ...



Gosh, that just doesn't sound healthy to me.

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## GrauGeist (Jul 26, 2021)

Thumpalumpacus said:


> Gosh, that just doesn't sound healthy to me.


Agreed.
In the forum's "B-25 weapons" thread, there's a few photos of a B-25 that had eight nose-mounted .50s, two cheek packs (one per side with two .50s) and the upper turret locked forward = 14 .50MGs and these strafers raped Japanese shipping and ground targets.

Just imagine what could be done with a much larger platform.

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## Thumpalumpacus (Jul 26, 2021)

GrauGeist said:


> Agreed.
> In the forum's "B-25 weapons" thread, there's a few photos of a B-25 that had eight nose-mounted .50s, two cheek packs (one per side with two .50s) and the upper turret locked forward = 14 .50MGs and these strafers raped Japanese shipping and ground targets.
> 
> Just imagine what could be done with a much larger platform.



I get that, the thing that worries me is that the -32 has to be much less nimble, and a much bigger target carrying more aircrew.

The idea of a bomb-bay fuel tank on a -25 or -26 as mentioned above strikes me as more doable, but I'm no expert and defer to opinions better-informed. About 1100 miles round-trip Okinawa-Kyushu, no? Forsaking any bombs and burning that extra fuel first (once in cruise) might work if you can bring the plane's radius up by about 40%. I'm just spit-ballin', don't rake me over the coals!


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## GrauGeist (Jul 26, 2021)

It was about 500 miles from Okinawa to the southern air bases on Kyushu, so yes, figuring 1,100 miles is a solid number.

Historically, the strafers used to come in low and fast on their targets, hitting them hard and keeping their speed up to reduce chances of being hit by ground fire and they weren't doing much in the way of wild maneuvering during the process.

It should also be noted that the B-29s would come in low and fast during their bombing runs over Tokyo and other cities when they were fire-bombing - if memory serves right, some missions were as low as 5,000 AGL.

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## SaparotRob (Jul 26, 2021)

That's right. I forgot the B-29's missions changed to low and fast at night. 
If there were such a B-32 strafer mission, could a variety of fighters (sea and air) have been used for escort in relay? To minimize carriers exposure to land based air power?

Just how many wing mounted gun pods do you think that monster could carry?


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## GrauGeist (Jul 26, 2021)

SaparotRob said:


> That's right. I forgot the B-29's missions changed to low and fast at night.
> If there were such a B-32 strafer mission, could a variety of fighters (sea and air) have been used for escort in relay? To minimize carriers exposure to land based air power?
> 
> Just how many wing mounted gun pods do you think that monster could carry?


I'm sure that P-51s and P-47s would the workhorses of the show regardless of who was going in.

As far as weapons...Lord have mercy, where to start?
Batteries of .50MGs or 20mm cannon or even perhaps some 37mm cannon?
With a solid nose, a savage battery of .50s could be installed, perhaps supplemented with 20mm cannons in the mix.
Also perhaps an option like was done with the Ju88 and IL-2, with weapons mounted beneath firing down and forward at an angle.

Maybe equip it with a full strafing battery and pack one of the bomb bays with anti personnel bomblets for good measure when making passes behind the beach-heads and trenches?

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## gumbyk (Jul 26, 2021)

GrauGeist said:


> Maybe equip it with a full strafing battery and pack one of the bomb bays with anti personnel bomblets for good measure when making passes behind the beach-heads and trenches?




A bomb-bay full of flechettes?


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## 33k in the air (Jul 26, 2021)

GrauGeist said:


> The A-20, A-26, B-25 and P-61 all conducted ground attack in the ETO.



But not in the same style as was done in the Pacific.

There were a couple of attempts early on to use B-26s in the ETO in the same manner as the strafer B-25s in the Pacific. But the much more capable and numerous German low-level flak chewed up such raids. The result was the switch to bombing from medium altitudes.



GrauGeist said:


> In the forum's "B-25 weapons" thread, there's a few photos of a B-25 that had eight nose-mounted .50s, two cheek packs (one per side with two .50s) and the upper turret locked forward = 14 .50MGs and these strafers raped Japanese shipping and ground targets.
> 
> Just imagine what could be done with a much larger platform.



Seems to me one has much greater tactical flexibility with two or three attack B-25s or A-26s than one B-32 gunship.

Swarming the target has its advantages.

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## Thumpalumpacus (Jul 26, 2021)

GrauGeist said:


> It was about 500 miles from Okinawa to the southern air bases on Kyushu, so yes, figuring 1,100 miles is a solid number.
> 
> Historically, the strafers used to come in low and fast on their targets, hitting them hard and keeping their speed up to reduce chances of being hit by ground fire and they weren't doing much in the way of wild maneuvering during the process.
> 
> It should also be noted that the B-29s would come in low and fast during their bombing runs over Tokyo and other cities when they were fire-bombing - if memory serves right, some missions were as low as 5,000 AGL.



5000 AGL is a bit higher than what the -25s &-20s were pulling in SoWasPac, and though they weren't doing aerobatics, from what I've read they were indeed kicking rudder for spray and targeting, and a B-32 just isn't going to be as responsive, I don't think.

A strafing mission _a la_ A-20/B-25 tactics was what, 500 AGL tops? Asking a plane 1.5x as long and wide to pull that off is asking for a lot of trouble. I'd rather mod a plane that's already shown its ability to perform the mission rather than introduce a new plane as an experiment in the big show.

Hell, use the B-32 for photo-recon (as we did in August 45) in order to identify targets for the strafers/GA aircraft -- i.e., as a force-multiplier rather than a direct-attack weapon. Identify dumps, hidden strips, etc, and let Kenney's kids do what they did best. Better than retraining B-32 crews for a difficult mission, to my thinking.


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## Thumpalumpacus (Jul 26, 2021)

GrauGeist said:


> I'm simply playing Devil's advocate here, the idea of a monster gunship intrigues me and when I first heard the idea, it occurred to me that the B-32, of all the heavy bombers made, could actually pull it off.



And just so we're clear, I'm liking this as a thought-experiment and enjoying what it's making me think, as well.

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## 33k in the air (Jul 26, 2021)

Thumpalumpacus said:


> The idea of a bomb-bay fuel tank on a -25 or -26 as mentioned above strikes me as more doable, but I'm no expert and defer to opinions better-informed. About 1100 miles round-trip Okinawa-Kyushu, no?



According to the Characteristics Summary of the B-25J bomber version, with 1,137 gallons of fuel, 4,000 lbs of bombs, and a mission altitude of 10,000 feet, the aircraft had a combat radius of 685 nautical miles (788 statute miles).

According to the Characteristics Summary of the A-26B attack version, with 1,360 gallons of fuel, 4,000 lbs of bombs, and a mission altitude of 10,000 feet, the aircraft had a combat radius of 860 nautical miles (989 statute miles).

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## Shortround6 (Jul 26, 2021)

Admiral Beez said:


> We're going to need to need to source or develop a 1,000 lb. APHE bomb.


We need to define what a APHE bomb is.

*A*rmor
*P*iercing
*H*igh
*E*xplosive

Was term often used in artillery or tank gun ammunition.
Less so in naval guns, they had different terminology even if perhaps the intent was the same.
For bombs the criteria was way, way different.

Converting naval shells to bombs was a somewhat cheap way to get a small number of bombs in a hurry.
I say somewhat cheap because it took an awful lot of machining on the body of the shell to make even a 1/2 way satisfactory bomb. It was faster than designing and building a new bomb casing of forged steel however. Or depended upon the ability (or inability) to provide quality forgings of the appropriate size. The Japanese AP bombs converted from 16 in naval shells were almost 500lbs lighter than the parent shell. The interior of the shell was bored out and accommodated around twice the explosive.

The British 500lb SAP (Semi Armor Piercing) held 18% explosive by weight.

Naval AP shells were most often between 2 and 4 % HE content. Some navies may have used the term APHE, others used the term "common" shell and some used SAP. HE content was from about 4% to a bit over 6%. These were base fused. Naval HE shells often were nose fused and the HE content was usually between 6% and 10%.

The British used a lot of crappy bombs in the early part of the war. Not only were there no 1000lb bombs but the standard British HE bomb design, the G.P. Series was about 29-31% explosive by weight. The US GP bombs and the German SC series were around 50% explosive by weight. The British got to this level with the M.C. series of bombs. (Medium Case). But the 1000lb MC bomb didn't go into production until the spring of 1943. 
The British seemed to be obsessed with using the cheapest steel they could for bomb bodies and artillery shells. Cheap may be good but not if you have to fire (or drop) a lot more shells/bombs to get the same target effect. 

Back to the Skua dive bomber. With a better engine it probably could have carried a bigger bomb, heck, just put a constant speed prop on it might have done wonders for load carrying ability. Now do a reality check and figure out the most likely target/s. The Twins and the Bismarck or the 3 pocket battleships, several heavy cruisers, 6-7 light cruisers, 20-30 destroyers plus large torpedo boats. You only need AP bombs for the first 3. AP bombs might just go right through the light cruisers and smaller. 
A 1000lb bomb with 50% explosive will cause major damage to most ships if it gets through even one un-armored deck before exploding. They are very dangerous in the case of a near miss (very near) as that is as much or more explosive than many aerial torpedoes used. Damage from 5-10ft away is going to be very similar to a torpedo hit. 
You can't really plan on it but it does increase the target area a bit.

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## GrauGeist (Jul 26, 2021)

gumbyk said:


> A bomb-bay full of flechettes?


More like the M41, which was a 20 pound fragmentation bomb usually wired together in clusters.

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## GrauGeist (Jul 26, 2021)

33k in the air said:


> But not in the same style as was done in the Pacific.
> 
> There were a couple of attempts early on to use B-26s in the ETO in the same manner as the strafer B-25s in the Pacific. But the much more capable and numerous German low-level flak chewed up such raids. The result was the switch to bombing from medium altitudes.


They were using the B-26 in low level bombing runs, not as a strafer.
Many of the medium bombers used that conducted low level bombing attacks in Europe and the Med suffered a high attrition rate until they changed to more medium altitudes.


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## Shortround6 (Jul 26, 2021)

German low level AA was in a whole different category from Japanese low level AA.
Both in quality and quantity. Not saying the Japanese were ineffective but the losses should have been lower.

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## Thumpalumpacus (Jul 26, 2021)

Shortround6 said:


> German low level AA was in a whole different category from Japanese low level AA.
> Both in quality and quantity. Not saying the Japanese were ineffective but the losses should have been lower.



I don't think the Japanese had anything the quality of German static, or especially mobile, low-level AA. But large targets flying low throws a wrench into it.


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## GrauGeist (Jul 27, 2021)

The Japanese Anti-Air Defenses over their cities did account for quite a few Allied losses - not on the scale of the German's 88s or 120s, but they were there.


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## 33k in the air (Jul 27, 2021)

Did the technology exist in 1945 to turn a B-29 or B-32 into a AC-130 style gunship? Obviously infrared sensors are off the table, but were airborne-capable optical sights of the time good enough? Radar-directed options as well perhaps?


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## 33k in the air (Jul 27, 2021)

GrauGeist said:


> They were using the B-26 in low level bombing runs, not as a strafer.
> Many of the medium bombers used that conducted low level bombing attacks in Europe and the Med suffered a high attrition rate until they changed to more medium altitudes.



Yeah, I meant low-level bombing aspect to it.

Although it's interesting to note the USAAF B-26s had their four 'package' side .50-cal MGs mounted, which would be of little value in medium altitude bombing. (I recall reading the 'package' guns were retained by the USAAF but were removed from RAF-operated Marauders.)


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## GrauGeist (Jul 27, 2021)

The Germans had several infrared systems like the ZG 1229 and ZG 1250 and the Allies had the TABBY systems, but for aerial aiming, I'm not sure the ranges needed for viable targeting were technologically available at the time.

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## MiTasol (Jul 27, 2021)

GrauGeist said:


> It was proposed to make the B-32 a gunship (strafer) like the A-20, B-25 and A-26s were.
> 
> I tried to imagine just how many .50s (or 20mm, like the P-61) could be applied. Especially since it would not be carrying bombs.



I think that would depend on where they put the guns. All in the nose probably not so many unless they used fuel ballast tanks (down the back and keep them full until the ammo is used).

This is common now but would probably have been a first if done then


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## MiTasol (Jul 27, 2021)

Thumpalumpacus said:


> I don't think the Japanese had anything the quality of German static, or especially mobile, low-level AA. But large targets flying low throws a wrench into it.


agreed though for the first couple of days the gunners would have been confused by the size and especially speed and screwed up their lead allowances. Lead as in angle not lead as in weight (gosh I love English with its same word totally different meanings)

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## GrauGeist (Jul 27, 2021)

MiTasol said:


> I think that would depend on where they put the guns. All in the nose probably not so many unless they used fuel ballast tanks (down the back and keep them full until the ammo is used).
> 
> This is common now but would probably have been a first if done then


Makes for one heck of a "what if", though.
Not only figuring proper outfitting of weaponry, but how to employ it.
Since it had great range, the approach to the target area would be open to quite a few possibilities.

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## pbehn (Jul 27, 2021)

There are model kits of rocket projectors that they fitted in B-24 bomb bays, I havnt found a picture of the actual thing though.

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## Zipper730 (Jul 28, 2021)

drgondog said:


> Why? Its operating altitude was much lower than B-29 and B-29 ops from March 1945 to EOW showed that high altitude ops were less effective over Japan than traditional ETO ops.


Because, without a tunnel, you end up with two parts of the aircraft that are basically inaccessible to the other.

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## drgondog (Jul 28, 2021)

Zipper730 said:


> Because, without a tunnel, you end up with two parts of the aircraft that are basically inaccessible to the other.


So tell me again why B-32 needs a tunnel? for same design altitudes as B-24 and B-17 - which did not have tunnels?


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## Zipper730 (Jul 28, 2021)

The B-17 and B-24 far as I know have passage ways between the forward and rear compartments. The catwalk over the bomb-bay on those planes does the job


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## GrauGeist (Jul 28, 2021)

The B-32 had a catwalk similar to the B-24's


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## drgondog (Jul 28, 2021)

Zipper730 said:


> The B-17 and B-24 far as I know have passage ways between the forward and rear compartments. The catwalk over the bomb-bay on those planes does the job


That was my point regarding why the B-32 did Not have a pressurized tunnel similar to B-29.


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## MiTasol (Jul 28, 2021)

drgondog said:


> So tell me again why B-32 needs a tunnel? for same design altitudes as B-24 and B-17 - which did not have tunnels?


Because the B-34 was pressurized and the others were not. Without a tunnel you would have to depressurize both areas to allow anyone to travel between.


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## swampyankee (Jul 28, 2021)

I seems to be a poor use of resources to use a B-32 as a ground attack platform when it would a) require escorts and b) require a lot more logistics support.

If it's escorted, that means fighters and dedicated attack aircraft can do the same task. Considering that each B-32 requires, itself, at least as much support as four fighters, plus the support for its escorts, it seems unlikely this is a sensible role to assign to a heavy bomber.

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## nuuumannn (Jul 28, 2021)

33k in the air said:


> Obviously infrared sensors are off the table, but were airborne-capable optical sights of the time good enough? Radar-directed options as well perhaps?



Putting a big airframe low to the ground and at high speeds repeatedly tends to weaken the airframe a bit. Fatigue might become an issue. The B-32's wing was designed for high altitude, not low altitude. Vibration could set in, throwing the pilot's aim, all manner of things might happen. Unless trials were done it would be impossible to say exactly what might or might not work. 

The British put their post-war high altitude heavy bombers to work into a low altitude role, the Valiant didn't respond well to it, having to be withdrawn early because of fatigue (following the Valiant stress failures the Victor underwent extensive low-level trials and redesign to improve its fatigue life). The RAF operated the Buccaneer at low altitude through hills and valleys which induced structural weakness that rendered many aircraft useless, despite the type being designed for low altitude ops; the Bucc was for flying low over water, not flying through mountain ranges.

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## GrauGeist (Jul 28, 2021)

We could also say the same for the bombers that were conducting bombing missions as well as any other types doing ground attack missions (P-47, B-25, etc.).

Japanese home airspace was going to be hotly contested, no matter what Allied type entered it.

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## 33k in the air (Jul 28, 2021)

nuuumannn said:


> Putting a big airframe low to the ground and at high speeds repeatedly tends to weaken the airframe a bit. Fatigue might become an issue. The B-32's wing was designed for high altitude, not low altitude. Vibration could set in, throwing the pilot's aim, all manner of things might happen. Unless trials were done it would be impossible to say exactly what might or might not work.



Hence why I was wondering if making it a predecessor of the AC-47 gunship might have worked, rather than a sort of super B-25 strafer.


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## nuuumannn (Jul 28, 2021)

33k in the air said:


> Hence why I was wondering if making it a predecessor of the AC-47 gunship might have worked,



Clearly, it did. Turning the B-32 into the same might result in a different outcome.


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## Thumpalumpacus (Jul 28, 2021)

MiTasol said:


> agreed though for the first couple of days the gunners would have been confused by the size and especially speed and screwed up their lead allowances. Lead as in angle not lead as in weight (gosh I love English with its same word totally different meanings)



True enough. Anyone who's seen a C-5 on final approach knows how deceptive a large plane flying low can be.



33k in the air said:


> Did the technology exist in 1945 to turn a B-29 or B-32 into a AC-130 style gunship? Obviously infrared sensors are off the table, but were airborne-capable optical sights of the time good enough? Radar-directed options as well perhaps?



I'd bet radar isn't an option given the state of the technology at the time. "Look-down/shoot-down" wasn't a thing then because ground-clutter fouled the screens -- and I bet that would apply to ground targets as well, especially since the targets are not moving and are presumably camouflaged as well, which may interfere with return-reception.

Optical would seem to hold more promise, as gyros were growing more complex, and a slaving-locking system for the guns wouldn't seem too hard to cobble together -- we did about the same for the B-29's defensive guns. Would the planes have the room for the heavy ordnance of the Spectre? Doubtful; a slender fuselage has less room to accommodate recoil, and I'd guess the -29 and -32 weren't stressed for sideways forces like that anyway. But still, hosing a target down with 37mm and a few fifties seems most possible of the three options, from either of the two airplanes.

I don't know how sensitive IR systems were at the time so can't offer an intelligent opinion there.

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## BiffF15 (Jul 28, 2021)

The interesting thing is both the B-1 (Bone) and the B-52 (Buff) became quite useful for Close Air Support (CAS) in Afghanistan. Hours and hours of loiter time, unbelievable amount of weapons (Precision Guided Munitions AKA PGMs), air refuelable. The grunts loved having hours of hate circling above them ready at a moments notice.

Cheers,
Biff

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## Thumpalumpacus (Jul 28, 2021)

BiffF15 said:


> The interesting thing is both the B-1 (Bone) and the B-52 (Buff) became quite useful for Close Air Support (CAS) in Afghanistan. Hours and hours of loiter time, unbelievable amount of weapons (Precision Guided Munitions AKA PGMs), air refuelable. The grunts loved having hours of hate circling above them ready at a moments notice.
> 
> Cheers,
> Biff



They both have the benefit of size (big fuel tanks, large lifting), allowing an expansion of weapons-kit to accommodate better, stand-off arms. The Buff's lifespan already speaks to that ability, and no doubt the Bone's will as well, albeit more technical complication for wings etc.

It's an interesting development -- almost as if the stealth fighters are the destroyers scouting for the fleet while defending themselves, and the bombers are the BBs laying back behind the line to target what's spotted. Done at 600 kts rather than 25 or 30.


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## tyrodtom (Jul 28, 2021)

All the big ground attack aircraft the USAF tried later , AC-47, AC-119, AC-130, were siting ducks when there was anything bigger than light AA present on the ground.

And I hate to think how bad it might have been if they had been up against any kind of aerial opposition.

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## Zipper730 (Jul 29, 2021)

drgondog said:


> Why? Its operating altitude was much lower than B-29 and B-29 ops from March 1945 to EOW showed that high altitude ops were less effective over Japan than traditional ETO ops.


I'm surprised it took so long to be introduced to operational use. It's first flight was around the same time as the B-29.

Regarding high altitude performance, from what I remember the problem with the B-29 had to do with the following

Slow climb-rate: Owing to the aircraft being heavier than initially anticipated, the aircraft was underpowered. Further, the cowling didn't provide adequate cooling at lower speeds (if I recall the R-3350's had magnesium accessory components which made fires more likely, but the B-29's magnesium spar made any engine fire a very serious problem) so the climb-speed had to be above what would be considered remotely optimum. A lot of power is needed to climb the aircraft up and that burns a lot of gas.
Slow acceleration rate: The plane was underpowered and acceleration appeared to be poorer than desired and that would probably mean the plane would take longer to reach the cruise speeds and require higher power settings to cruise at the desired speed than had more engine power been available.
Cowling-flap design: If I recall the position of the cowl-flaps had a serious effect on the plane's cruising speed. I'm not sure if there was anything unusual about the cowl-flaps or simply due to the plane being underpowered.
Is there anything I'm missing?


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## 33k in the air (Jul 29, 2021)

Zipper730 said:


> I'm surprised it took so long to be introduced to operational use. It's first flight was around the same time as the B-29.



The B-32 ran into a lot of development issues. The first prototype had a B-24 style twin rudder tail. It wasn't until 1943 that a B-32 prototype that closely resembled the production aircraft finally took flight.

The B-32 was ordered as a back-up to the B-29, and once the latter had proved itself, the need for the B-32 diminished, particularly since it wasn't pressurized and thus couldn't operate at high altitudes the way the B-29 did. The B-32 also carried less fuel than the B-29s with center fuel tank.


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## wuzak (Jul 29, 2021)

Zipper730 said:


> Cowling-flap design: If I recall the position of the cowl-flaps had a serious effect on the plane's cruising speed. I'm not sure if there was anything unusual about the cowl-flaps or simply due to the plane being underpowered.



I believe this was also an issue with B-29s., though I am not sure about when cruising.

From what I understand, B-29s taking off from shorter than ideal runways on their island bases while being overloaded had to carefully set the cowling flaps so that the engine did not overheat and the drag was low enough that the required take-off speed could be reached before the end of the runway.


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## PAT303 (Jul 30, 2021)

wuzak said:


> From what I understand, B-29s taking off from shorter than ideal runways on their island bases while being overloaded had to carefully set the cowling flaps so that the engine did not overheat and the drag was low enough that the required take-off speed could be reached before the end of the runway.

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## Niceoldguy58 (Jul 31, 2021)

After a lot of research on the topic, I've long since come to the conclusion that the R-3350 of WWII was an absolutely execrable engine in all aspects. In fact, it wasn't until a complete redesign of the engine after WWII that it could be considered useful vs dangerous. And that was due to Chrysler's work on the engine. 

I have often wondered what might have been the case if the USAAF had not been so US-centric and used the Bristol Centaurus "bomber engine" on both the B-29 and the B-32. I suspect that both aircraft would have been substantially safer and earlier in their combat usage had that been the case.

AlanG


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## GrauGeist (Jul 31, 2021)

Niceoldguy58 said:


> After a lot of research on the topic, I've long since come to the conclusion that the R-3350 of WWII was an absolutely execrable engine in all aspects. In fact, it wasn't until a complete redesign of the engine after WWII that it could be considered useful vs dangerous. And that was due to Chrysler's work on the engine.
> 
> I have often wondered what might have been the case if the USAAF had not been so US-centric and used the Bristol Centaurus "bomber engine" on both the B-29 and the B-32. I suspect that both aircraft would have been substantially safer and earlier in their combat usage had that been the case.
> 
> AlanG


So would the USAAF have purchased the engines from Britain (assuming that the British had any to spare) or would the U.S. have had to tool up a manufacturing plant (like Packard did) and make their own.
If the latter, how long would that have taken to get a substantial number built and who would have made them?

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## swampyankee (Jul 31, 2021)

Niceoldguy58 said:


> After a lot of research on the topic, I've long since come to the conclusion that the R-3350 of WWII was an absolutely execrable engine in all aspects. In fact, it wasn't until a complete redesign of the engine after WWII that it could be considered useful vs dangerous. And that was due to Chrysler's work on the engine.
> 
> I have often wondered what might have been the case if the USAAF had not been so US-centric and used the Bristol Centaurus "bomber engine" on both the B-29 and the B-32. I suspect that both aircraft would have been substantially safer and earlier in their combat usage had that been the case.
> 
> AlanG


Much more likely would have been to use the Allison V-3420. While the Centaurus was a great engine, I don't think it would be available in time

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## wuzak (Jul 31, 2021)

swampyankee said:


> Much more likely would have been to use the Allison V-3420. While the Centaurus was a great engine, I don't think it would be available in time



Certainly not in the numbers required.


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## Niceoldguy58 (Aug 2, 2021)

MIflyer, based on what I recall in my B-32 documents your assertion about using the B-32 as essentially a 4-engined attack plane is correct.

And it is also one hell of a thing to imagine....

The concept was not new. 150 sets (4 guns each) of .50 cal. packet guns were produced for mounting on 10th and 14th AF B-24s. I have one photo of this and, while I have the records ordering the production of the packets I have yet to find anything else about the project. Still looking!

Regards,

AlanG

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## ThomasP (Aug 2, 2021)

Hey Niceoldguy58,

This may not be the same thing, but I remember reading about a plan to fit 4x .50 cal guns to B-24s (under the nose or in the forward bomb bay?) for jobs similar to those carried out by Coastal Command Liberators. It may even have been for the RAF's Coastal Command airframes but I do not recall.


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## Greg Boeser (Aug 2, 2021)

Martin had developed a bomb bay pack of 4 x 20mm cannon for the B-26, but it never went into production.


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## Admiral Beez (Aug 5, 2021)

PAT303 said:


> Well I suppose they were busy building masterpieces such as the Barracuda, a plane of such brilliance that it was replaced with the plane it was designed to replace!!!!!.


Put the intended Griffin engine into the Barracuda and we have a good TSR.


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## Shortround6 (Aug 5, 2021)

Admiral Beez said:


> Put the intended Griffin engine into the Barracuda and we have a good TSR.


If the engine had been ready on time they would have done it.


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## swampyankee (Aug 5, 2021)

Conventional designs are common because they work. The P-39's layout was a clever solution to the demand for a cannon that was too heavy and bulky to mount in the wings and not likely synchronizable. While the P-39 was useful, it was far from perfect: the engine location severely restricted fuel capacity and resulted in c/g problems as ammunition was expended.


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## Admiral Beez (Aug 5, 2021)

swampyankee said:


> Conventional designs are common because they work. The P-39's layout was a clever solution to the demand for a cannon that was too heavy and bulky to mount in the wings and not likely synchronizable. While the P-39 was useful, it was far from perfect: the engine location severely restricted fuel capacity and resulted in c/g problems as ammunition was expended.


Did Bell Aircraft design and produce anything fixed wing that wasn't either a poor compromise or just a failure?


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## tyrodtom (Aug 5, 2021)

Admiral Beez said:


> Did Bell Aircraft design and produce anything fixed wing that wasn't either a poor compromise or just a failure?


X-1 ?

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## GrauGeist (Aug 5, 2021)

Admiral Beez said:


> Did Bell Aircraft design and produce anything fixed wing that wasn't either a poor compromise or just a failure?


About the only aircraft they built (that wasn't a rocket or a helicopter) that performed well, was the X-5, which was based on the Messerschmitt P.1101


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## special ed (Aug 5, 2021)

A Wings or Airpower article had photos of the X-5 reconstruction from the P.1101. Much of the airframe is the German aircraft.

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## GrauGeist (Aug 5, 2021)

special ed said:


> A Wings or Airpower article had photos of the X-5 reconstruction from the P.1101. Much of the airframe is the German aircraft.


The captured P.1101 was damaged in transit.
The two X-5s that Bell made were of all new construction.

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## special ed (Aug 5, 2021)

I'll see if I can find the data.


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## GrauGeist (Aug 5, 2021)

Here's a detailed history of the X-5 from NASA:
NASA Armstrong Fact Sheet: X-5 Research Aircraft

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## nuuumannn (Aug 5, 2021)

Shortround6 said:


> If the engine had been ready on time they would have done it.



The first production Griffons were allocated to Firefly and Spitfire production, better use for them, to be honest.


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## nuuumannn (Aug 5, 2021)

special ed said:


> A Wings or Airpower article had photos of the X-5 reconstruction from the P.1101. Much of the airframe is the German aircraft.



hmm, not really, the Bell X-5s, as Dave said were built from the ground up by Bell. The P.1101 was accidentally dropped while being delivered to Bell, but was used for testing the fit of possible engine types and there was a plan to flight test it, but the damage done and small size, which meant it couldn't properly trial the engines under test meant this didn't happen. There is a photo of it fitted with a J35 engine.

The X-5 was designed from scratch and there are a few structural differences between the two aircraft. The P.1101 was fitted with Me 262 outer wing panels and the tailplanes were made of wood. The fuselage contours were quite different between the two.

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## GrauGeist (Aug 5, 2021)

To add to Grant's info, the X-5 was slightly larger, too.
Going by memory: 3 feet longer and a 3 foot wider wing-span (wings fully extended at 20°).

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## Reluctant Poster (Aug 12, 2021)

wuzak said:


> If you mean fuel injected R-3350s, then probably there were a few by the end of the war. Someone else may have more details.


The B29s used to drop the atomic bombs used fuel injection.


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## Reluctant Poster (Aug 12, 2021)

ThomasP said:


> Hey Niceoldguy58,
> 
> This may not be the same thing, but I remember reading about a plan to fit 4x .50 cal guns to B-24s (under the nose or in the forward bomb bay?) for jobs similar to those carried out by Coastal Command Liberators. It may even have been for the RAF's Coastal Command airframes but I do not recall.
> View attachment 635513


It was for costal command. They also tried rockets, but eventually decided close combat with a uboat wasn’t sensible. Depth charges and homing torpedoes were more practical.


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## pbehn (Aug 12, 2021)

Reluctant Poster said:


> It was for costal command. They also tried rockets, but eventually decided close combat with a uboat wasn’t sensible. Depth charges and homing torpedoes were more practical.


I think that reflects the difference between attacking during daylight and night time?


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## ThomasP (Aug 12, 2021)

I believe the .50s were intended for Flak suppression during the bombing/DC run.


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## Reluctant Poster (Aug 12, 2021)

pbehn said:


> I think that reflects the difference between attacking during daylight and night time?


Convey protection was done mostly by day. Leigh light nighttime attacks were done in the bay of biscay on uboats heading out on patrol. B24 were used on long range Atlantic convoy escort.


ThomasP said:


> I believe the .50s were intended for Flak suppression during the bombing/DC run.


Either you are strafing the uboat or doing a depth charge run. You can’t do both at the same time. A flexible 50 cal in the nose is a better choice. CC Halifaxes often substituted a 50 for a 303 in the nose. Shackletons had aimable 20 mms in the nose.


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## ThomasP (Aug 12, 2021)

Hey Reluctant Poster,

re strafing and dropping DCs during the same run

Given that I found more than 30 accounts of strafing and dropping DCs on the attack same run, within 10 minutes search on the web . . . ??

The first site I visited mentions several such attacks at the following address:

"U-boat Successes against aircraft - The History - uboat.net"

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## 33k in the air (Aug 12, 2021)

I remember reading later in the war the tactic become to orbit a surfaced U-boat just out of range of its AA guns. If the U-boat stayed on the surface, it risked more aircraft or enemy surface ships showing up; if it started to dive, the patrol aircraft would swoop in and drop depth charges.

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## Reluctant Poster (Aug 13, 2021)

ThomasP said:


> Hey Reluctant Poster,
> 
> re strafing and dropping DCs during the same run
> 
> ...


Yes with flexible machine guns not fixed. My point is with fixed guns you have to aim the whole aircraft at the uboat which does not allow a proper path for a depth change attack. The discussion point was Coastal commands experiment with fixed guns similar to installations on B25s and 26s

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## ThomasP (Aug 13, 2021)

Hey Reluctant Poster,

They used fixed and trainable guns during the attack. If fixed they often attacked from head on or astern, obviating the angle off problem for the DC attack.


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## Reluctant Poster (Aug 13, 2021)

ThomasP said:


> Hey Reluctant Poster
> 
> They used fixed and trainable guns during the attack. If fixed they often attacked from head on or astern, obviating the angle off problem for the DC attack. Ad


I dont see any runs by aircraft with fixed guns other than mosquitoes wildcats and Avengers. The bigger multi engined aircraft have turrets or hand held guns. The Wildcats and Avengers worked as a team with the Wildcat strafing with the Avenger dropping the depth charges. I don’t believe Beafighters or Mosquitoes carried depth charges.
Incidentally one of my fathers old flying magazines from WWII had a picture of the Liberator with the fixed 20 mms with a caption claiming that the B24 was so agile that the RAF was using it as a fighter.


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## ThomasP (Aug 13, 2021)

Same page which refers to the u-boats that managed to shoot down attacking aircraft, page down to

27 December 1942
". . . flak hits to the cockpit area and starboard engine during the initial strafing run caused four depth charges dropped by the aircraft to fall wide by 80 to 250m" (CC Hudsons were fitted with 2x fixed .303 cal nose guns)

7 May 1943
". . . but then made a strafing attack from the bow and released six depth charges . . ." (CC Halifax GR Mk II VLR with a fixed .50 cal in the nose)

also

Coastal Command Liberator Mk I VLR fitted with a 4x20mm belly pack specifically for strafing u-boats and surface ships

Late-war Coastal Command Halifax GR Mk IIIC with a 4-gun belly pack (either 4x.50 cal or 4x20mm) specifically modded for strafing u-boats and surface ships

also

from THE HOLDING CAMPAIGN AT SEA, 1943-44 Australian War Memorial collection
Sunderland Mk II with the 4x.303 cal fixed guns, 2x per side of the nose (Australian sqdn mod) "The four fixed bow guns not only gave automatic smothering fire but also allowed the pilot to eliminate line error when carrying out a depth-charge attack while at the same time . . ."

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## Reluctant Poster (Aug 13, 2021)

ThomasP said:


> Same page which refers to the u-boats that managed to shoot down attacking aircraft, page down to
> 
> 27 December 1942
> ". . . flak hits to the cockpit area and starboard engine during the initial strafing run caused four depth charges dropped by the aircraft to fall wide by 80 to 250m" (CC Hudsons were fitted with 2x fixed .303 cal nose guns)
> ...


I stand corrected

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## wuzak (Aug 13, 2021)

Reluctant Poster said:


> I don’t believe Beafighters or Mosquitoes carried depth charges.



Not sure if the Mosquito carried depth charges operationally, but they were certainly trialled.

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## pinehilljoe (Aug 13, 2021)

Back to how to improve a design. What could you do to the Me-109F/G with 90 days of design time and minimal tooling change to make a 400mph class fighter?
-design out the mass balance horns on the wings
-retract the tail wheel
-stop painting the aircraft, and go to polished aluminum finish, the operational life of a 109 could not have been that long, who needs the paint.
-fully cowl the landing gear
-use a bubble canopy
-could the oil cooler design have been modified to drop the intake below the wing boundry layer, and redesign to use the Meridith affect?
Any others?


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## Shortround6 (Aug 13, 2021)

pinehilljoe said:


> Back to how to improve a design. What could you do to the Me-109 with 90 days of design time and minimal tooling change to make a 400mph class fighter?
> -design out the mass balance horns on the wings
> -retract the tail wheel
> -fully cowl the landing gear
> ...



First 3 shouldn't be much trouble.
Modifying the windscreen area from that contraption that looks like a refuge from an 1800s blacksmith's shop would certainly bring some improvement. Putting something like a Malcom hood over pilot may give better vision to the rear but might cost a few of the MPH picked up with the better windscreen. Cutting down the rear fuselage may be somewhat harder. 




One prototype, maybe more?
Against is the fact that the extra height of the rear fuselage provided keel area, often made up with larger vertical stabilizer or fin added in front of stabilizer, all planes are different so I won't guess how much modification needed for that. Some planes got more powerful engines about the same time they got bubble canopies and would need more "keel area" for that reason so it does get confusing. 
2nd fact is that if you cut down the height of the rear fuselage with no other changes you reduce the beam strength. Maybe slightly heavier fuselage skin can compensate? maybe the thinner fuselage is still strong enough to handle loads? 
3rd consideration, unless well done, the "bubble" may cause more drag than the highback fuselage due to turbulence at the rear of the canopy. I believe the P-51B/C was faster than the P-51D for this reason (at least partially, there were some other changes) when using the same engines. 
Improved vision may be worth a few MPH? 
For the Germans such changes have to be made in a number of different factories. Not just 2 or 3. 

As far as the oil cooler goes, It is under the nose, the radiators are under the wing. 
Using the Meredith effect was a lot harder than it appears. You need to slow down the incoming air by using a larger duct near the radiator or oil cooler than the opening and then you need to narrow the exit duct in a gradual manner so you don't create turbulence/drag in the duct. If your transition of cross section area isn't done right you don't get much total effect. Part of the "effect" as used in the Mustang was that the Mustang used a very large radiator and the air flow though it was much lower than the airspeed of the airplane and since drag is proportional to speed this meant they radiator itself and less drag than a smaller radiator with a higher speed airflow. Mustang had the room (size of aircraft) to allow for the changes in duct size.

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## Admiral Beez (Aug 13, 2021)

How better would British aircraft have been if the whole sleeve valve idea was rejected by Bristol and instead the firm focused on improving and enlarging its poppet valve Mercury and Pegasus? There's also the Hydra, but that's adding needless complexity to a need that can be addressed with more displacement and more rows of larger cylinders.


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## Trilisser (Aug 13, 2021)

1. Sleeve-valves were superior. Period. 
2. Pure aluminium finish on the 109? Ugly! Would transform a military aircraft to a pimp ride. 
3. Bf 109G-2/6: Delete fuselage machine guns altogether (MG 17 was next to worthless and the MG 131 not much better) and make underwing cannons permanent. 
4. P-39/P-63: Add wingtip fuel tanks to boost fuel capacity. 
5. P-51B/D/H: Remove the 0.5 MGs and use 4 20 mm cannon instead. The same for the F6F and P-47 too. USN BuOrd considered one 20 mm equal to 3 x 0.5" in firepower. 
6. Fw 190: Redesign (originally) the wing with large Fowlers with a stick operated (like in the J2M) manoeuvre position. 
7. The original Bf 109 design should have looked like the Finnish Pyörremyrsky. The PM had some 20 % bigger wing, more spacious fuselage, yet was almost as fast as the 109G with the same engine thanks to its cleanliness. The PM handled much better all-around.


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## Glider (Aug 13, 2021)

Reluctant Poster said:


> I dont see any runs by aircraft with fixed guns other than mosquitoes wildcats and Avengers. The bigger multi engined aircraft have turrets or hand held guns. The Wildcats and Avengers worked as a team with the Wildcat strafing with the Avenger dropping the depth charges. I don’t believe Beafighters or Mosquitoes carried depth charges.
> Incidentally one of my fathers old flying magazines from WWII had a picture of the Liberator with the fixed 20 mms with a caption claiming that the B24 was so agile that the RAF was using it as a fighter.


A lot of CC aircraft were armed with fixed forward firing cannons and or MG's. The idea was to try and knock out the AA gunners at range whilst attacking levelling out for the DC run. The run was the same and fire could be opened at quite a range say 1,000 yard when closing and with luck by the time you reach the U Boat the gun crew will be out of action. 

On the attached video you can clearly see the 4 x 303 fitted in this aircraft





short sunderland flying boat - Bing video







www.bing.com


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## swampyankee (Aug 13, 2021)

Trilisser said:


> 1. Sleeve-valves were superior. Period.
> 2. Pure aluminium finish on the 109? Ugly! Would transform a military aircraft to a pimp ride.
> 3. Bf 109G-2/6: Delete fuselage machine guns altogether (MG 17 was next to worthless and the MG 131 not much better) and make underwing cannons permanent.
> 4. P-39/P-63: Add wingtip fuel tanks to boost fuel capacity.
> ...



1) Yet no one other than the British used them in production aircraft engines. While they did (at least according to Charles Fayette Taylor) provide better volumetric efficiency, they also provided significantly greater mechanical complexity and more difficult manufacturing. In other words, they may have been somewhat superior but not enough better for anyone else to actually use them in a production engine.

2) Natural aluminum finish was largely _de rigueur _for post-war military aircraft. I _suspect_ that many WW2 era, all-metal aircraft were painted at least partly because many "all-metal" aircraft weren't, with things such as fabric-covered control surfaces or wooden empennages.

3) Getting rid of them may enable some general aerodynamic clean-up, as the Bf109 was, according to all the sources I've seen, owner of the highest zero-lift drag coefficient of any single-engine monoplane fighter to serve through WW2.

4) I wonder how that would work in combat. Tip tanks can be drag-neutral, so the only real question would be roll rate and handling with them filled.

5) The problem with this is that the US severely mishandled production of the Hispano 20 mm during the war. But, yes, they were considerably superior to the M2 Browning.

6) No comment

7) No comment.

------

I believe there is one US fighter which could be "redesigned" with minimum need for a time machine and a retroscope: the P-61. While I believe the P-39 was far from an optimum design, I cannot see any solution that would meet the USAAC spec for a 37 mm cannon without an engine designed for a hub-mounted cannon.

My P-61 revision would be straightforward: no turret, a conventional, not twin-boom, layout, tandem seating for the pilot and radar operator, and all guns (4 x 20 mm) mounted beneath the nose. If one is wed to the twin-boom design, well, fine, but that way lies greater wetted area (more skin friction drag) and likely more structural weight.

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## Zipper730 (Aug 13, 2021)

I was thinking about the P-61 with a turbochager and it's effects with earlier horsepower settings on speed. I did some very crude calculations based on manifold pressure to horsepower for the baseline P-61A/B supercharger gear based from a manual in a private message I sent to somebody awhile back. The 22500' figure I just added based on another R-2800 powered aircraft, and put the speed setting based on the fact that I know the top speed was 366 mph.






I'm not sure how the horsepower figures are so high for MCP as 1751 seems to be above the normal-rated setting, but these figures are what came from the manual (TAS, MAP and Altitude) with the exception of the critical altitude figure (22500') and the speed at altitude (the latter came from known performance figures of the P-61, and the former was a guess based on the R-2800).

With turbocharging, the figures seem generally to be quite a bit better, though I'm not sure how much thrust was produced by the R-2800's exhaust-stacks (as that would be lost). If I compute these figures right, I do get numbers just under 400 mph. It does seem that the only way to get around 430 is to add quite a bit more power.


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## Glider (Aug 13, 2021)

To be honest the P61 was simply way too big, too heavy, too complex and too late.

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## GrauGeist (Aug 13, 2021)

In lieu of the P-61, consider the XP-58.

If it weren't for the problematic X-1430 and V-3420 engines, it may have seen quite a few roles: interceptor, ground attack and perhaps night-fighter.

It's armament considerations even included four 37mm cannon.


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## pbehn (Aug 13, 2021)

swampyankee said:


> 1) Yet no one other than the British used them in production aircraft engines. While they did (at least according to Charles Fayette Taylor) provide better volumetric efficiency, they also provided significantly greater mechanical complexity and more difficult manufacturing. In other words, they may have been somewhat superior but not enough better for anyone else to actually use them in a production engine.
> 
> 2) Natural aluminum finish was largely _de rigueur _for post-war military aircraft. I _suspect_ that many WW2 era, all-metal aircraft were painted at least partly because many "all-metal" aircraft weren't, with things such as fabric-covered control surfaces or wooden empennages.


1) They also had problems of heat dissipation, special high copper alloys were developed to solve it.
2) Post war, most aircraft werent involved in a war where they could be shot up on the ground. Vulcan strategic bombers were all white until they had to fly at low level then they got camouflage on upper surfaces.

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## pbehn (Aug 13, 2021)

Glider said:


> A lot of CC aircraft were armed with fixed forward firing cannons and or MG's. The idea was to try and knock out the AA gunners at range whilst attacking levelling out for the DC run. The run was the same and fire could be opened at quite a range say 1,000 yard when closing and with luck by the time you reach the U Boat the gun crew will be out of action.
> 
> On the attached video you can clearly see the 4 x 303 fitted in this aircraft
> 
> ...


Like most conflicts it wasnt static. As depth charge attacks became more successful, U Boats especially in the Bay of Biscay were encouraged to fight it out on the surface rather than diving.


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## swampyankee (Aug 13, 2021)

pbehn said:


> 1) They also had problems of heat dissipation, special high copper alloys were developed to solve it.
> 2) Post war, most aircraft werent involved in a war where they could be shot up on the ground. Vulcan strategic bombers were all white until they had to fly at low level then they got camouflage on upper surfaces.



If I recall, North Vietnam's Air Force's MiGs were in natural metal. Of course, jets have another problem: smoke trails. The J-79s were pretty smokey.

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## Zipper730 (Aug 13, 2021)

Frankly, I think the USAAF shouldn't have given up on single-engined attack planes. The USN didn't and they worked very well.

BTW: Corrected from earlier


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## MiTasol (Aug 13, 2021)

Trilisser said:


> 1. Sleeve-valves were superior. Period.
> 2. Pure aluminium finish on the 109? Ugly! Would transform a military aircraft to a pimp ride.
> 3. Bf 109G-2/6: Delete fuselage machine guns altogether (MG 17 was next to worthless and the MG 131 not much better) and make underwing cannons permanent.
> 4. P-39/P-63: Add wingtip fuel tanks to boost fuel capacity.
> ...



In other words keep the A-36 wing


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## pbehn (Aug 13, 2021)

MiTasol said:


> In other words keep the A-36 wing


The P-51B/C and D were specifically escort fighters, I cant see a reason to impose the extra weight and drag of cannons onto it.


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## Thumpalumpacus (Aug 13, 2021)

Zipper730 said:


> Frankly, I think the USAAF should have given up on single-engined attack planes. The USN didn't and they worked very well.



The USAAF did sort of realize this and by 1944 most single-engined attack missions were done by fighters, some modded with hard-points. Neither 8th nor 9th AFs used dedicated single-engine bombers (A-24, A-25, etc), no? That's giving up on the concept of "single-engined bomber", and transforming it to "let's stick as much ordnance as we can on this fighter." It's a subtle but clear distinction, to me. The RAF did the same thing around the same timeframe.

The USN _had_ to keep with single-engined-bombers by dint of the carriers not being able to handle, regularly, the twins of the day. But once they could put rails/racks on Hellcats, they could back down the bomber complement.


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## 33k in the air (Aug 13, 2021)

pbehn said:


> The P-51B/C and D were specifically escort fighters, I cant see a reason to impose the extra weight and drag of cannons onto it.



Especially considering the .50-cal MGs were more than entirely sufficient to shoot down German (and Italian) fighters.

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## 33k in the air (Aug 13, 2021)

Zipper730 said:


> Frankly, I think the USAAF should have given up on single-engined attack planes. The USN didn't and they worked very well.



The Pacific theater was a very different environment from the European (and Mediterranean).

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## Shortround6 (Aug 13, 2021)

Trilisser said:


> 1. Sleeve-valves were superior. Period.
> 3. Bf 109G-2/6: Delete fuselage machine guns altogether (MG 17 was next to worthless and the MG 131 not much better) and make underwing cannons permanent.
> 4. P-39/P-63: Add wingtip fuel tanks to boost fuel capacity.


1. Actually they didn't prove to be much better. They were better than Bristol poppet valve engines but then Bristol did very little development work on the Poppet valve engines. 
The sleeve valves may have flowed more air. They seemed to have had a real problem with cooling at high power levels. There may have been problem using high boost which also limits take-off and combat power. Compare a Bristol radial to an equivalent P & W or Wright radial. And by equivalent I mean about the same size and about the same year of production. 
Since nobody ever said how much the Bristol sleeve valve engines cost we are left guessing. Guesses from British authors say about double the cost per HP compared to a poppet valve engine but nobody can prove that one way or the other. 

3. A MG 151/20 weighs about 2 1/2 times what an MG 131 does. The 20mm ammo is about 2.6 times heavier per round (averaging weights). Planes with the under wing 20mm guns were not noted for maneuverability. Slower initial role response and less climb may have been more important than loss of speed. 

4. Inside tanks? ( inplace of wing machineguns/ammo storage) or tip tanks like a P-80? 
Problems with the P-39/P-63 was limited internal fuel to fight and get home after external tank/s were punched off. 

P-63s could carry 3 external tanks (at least later ones) a 75 gallon non-self sealing tank under the fuselage and a non-self sealing 75 gallon tank under each wing. 
There was also a 64 gallon self-sealing slipper tank for under the fuselage. You do have to get the plane off the air-field when carrying large/multiple fuel tanks.

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## swampyankee (Aug 13, 2021)

pbehn said:


> The P-51B/C and D were specifically escort fighters, I cant see a reason to impose the extra weight and drag of cannons onto it.



What would the installed weight of 6 or 8 0.5 in M2 be vs 4 Hispano 20 mm? Consider those 4 Hispano would be the equivalent of 12 0.5 in M2.


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## 33k in the air (Aug 14, 2021)

swampyankee said:


> What would the installed weight of 6 or 8 0.5 in M2 be vs 4 Hispano 20 mm? Consider those 4 Hispano would be the equivalent of 12 0.5 in M2.



According to _America's Hundred Thousand_, the weight of a .50-cal MG was 70 lbs, and a 20mm cannon 129 lbs. The total weapon weights would be about:

4 x 20mm = 516 lbs
4 x .50-cal = 280 lbs
6 x .50-cal = 420 lbs
8 x .50-cal = 560 lbs

100 rounds of .50-cal ammunition weighed about 31 lbs; 100 rounds of 20mm weighed about 61 lbs.

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## MiTasol (Aug 14, 2021)

pbehn said:


> The P-51B/C and D were specifically escort fighters, I cant see a reason to impose the extra weight and drag of cannons onto it.


I was purely commenting on the previous post that suggested the P-51 should be fitted with 4 x 20mm cannon showing it had been done and that the USAAF for some reason killed the concept

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## GrauGeist (Aug 14, 2021)

MiTasol said:


> I was purely commenting on the previous post that suggested the P-51 should be fitted with 4 x 20mm cannon showing it had been done and that the USAAF for some reason killed the concept


The US M2 20mm was problematic and wasn't adopted as a primary weapon except for the P-61 and F6F-5N.


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## Reluctant Poster (Aug 14, 2021)

pbehn said:


> Like most conflicts it wasnt static. As depth charge attacks became more successful, U Boats especially in the Bay of Biscay were encouraged to fight it out on the surface rather than diving.


That only lasted about a month before Donitz ordered the Uboats to remain submerged during the day and only surface at night to recharge the batteries.
Note that the British introduced rockets shortly after the order to fight it out on the surface. A swordfish was the first aircraft to lanch a British rocket in anger sinking U 752 on May 23 1943.

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## drgondog (Aug 14, 2021)

MiTasol said:


> In other words keep the A-36 wing


The P-51NA/Mk !A wing - which did not have pylon system for bombs/combat tanks... an 10mph slower w/20mm than Mustang I.

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## drgondog (Aug 14, 2021)

Thumpalumpacus said:


> The USAAF did sort of realize this and by 1944 most single-engined attack missions were done by fighters, some modded with hard-points. Neither 8th nor 9th AFs used dedicated single-engine bombers (A-24, A-25, etc), no? That's giving up on the concept of "single-engined bomber", and transforming it to "let's stick as much ordnance as we can on this fighter." It's a subtle but clear distinction, to me. The RAF did the same thing around the same timeframe.
> 
> The USN _had_ to keep with single-engined-bombers by dint of the carriers not being able to handle, regularly, the twins of the day. But once they could put rails/racks on Hellcats, they could back down the bomber complement.


The A-36 Mustang was designed, proposed, and delivered as 'Low Level Attack Aircraft' - It was deployed and highly successful in all low level attack roles including specifically dive bombing and glide bombing - as well as being capable of defending itself. The Air Force did indeed use the A-24/-25 and not happy with inability to defend themselves.

The CAS Doctrine which emerged in 1941-42 was to deploy two types of aircraft to support US Army battlefield operations - Fast Attack Bomber (originally A-20) for low/medium level tactical strikes, and Fast Attack Fighter for Recon, Strafing, light bombing and capable of battlefield air superiority. The P-38/F-4 was originally tasked for fast battlefield recon but replaced by the emerging Mustang designs beginning with P-51-NA/F-6.

The doctrine based on Lord Cunningham's Desert Air Force tactics began to take root (AAF-HQ) in late 1942 and 43 and at the same time the P-51A contract and design supplanted the A-36. The A-36 was then abandoned as the primary battlefield fighter. It did not have continued production after first 500 and the new P-51A was deemed a superior fighter with superior range, bomb load and performance over the P-39 and P-40. By that time the the AAF Mustang evolution - from Allison 1S/1S supercharged engine based 20mm equipped/no bomb rack (P-51), to 6x0.50 cal/bomb rack/dive brake (A-36), to 4x0.50, bomb rack equipped, 1 Speed/1 Stage/water injected Allison (P-51A) - had morphed performance envelope to the P-51B-1 with Packard Merlin.

In May 1943 the new P-51A and B were tasked to replace all P-39 and P-40 in US TAC, specifically 9th AF. Zero were allocated to Strategic Air Forces.

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## drgondog (Aug 14, 2021)

Zipper730 said:


> Frankly, I think the USAAF should have given up on single-engined attack planes. The USN didn't and they worked very well.


So, in your mind the A-36, P-47, P-51 didn't work?


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## pinehilljoe (Aug 14, 2021)

Glider said:


> To be honest the P61 was simply way too big, too heavy, too complex and too late.


the first hand accounts by pilots in the old Wings and Airpower magazine agreed it was too slow. In the big picture it may have been better if the US had license built Mosquitos for the night fighter role.

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## Ascent (Aug 14, 2021)

pinehilljoe said:


> the first hand accounts by pilots in the old Wings and Airpower magazine agreed it was too slow. In the big picture it may have been better if the US had license built Mosquitos for the night fighter role.


How about licence building Beaufighters for the night fighter role? Replace the engines with something American made, I'm sure there are plenty of options for powerful radials, although I don't know enough about American radials to know what would be equivalent.

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## Shortround6 (Aug 14, 2021)

If the P-61 is too slow the Beaufighter is waaaaaaay to slow. The US did use a number of Beaufighters as night fighters in the Med. Closest US engine was the R-2600 and it won't offer much performance improvement.

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## pinehilljoe (Aug 14, 2021)

Ascent said:


> How about licence building Beaufighters for the night fighter role? Replace the engines with something American made, I'm sure there are plenty of options for powerful radials, although I don't know enough about American radials to know what would be equivalent.


The not-invented here, and the lobbies could never be overcome. Remember Curtis-Wright was the largest company in the USA at the time, bigger than GM. Curtis didnt build the P-61 but with that much money in the industry, the US wasnt going to license an aircraft. The only designs licensed in any number that I can think of were the DH-4, Canberra and Harrier, planes that were superior or unique.


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## GrauGeist (Aug 14, 2021)

Also have to consider the amount of time to find a manufacturer who will accept the job (Cessna, Beech) and then devote a manufacturing site for the project.
Then (assuming DH had jigs to spare) assemble a workforce and necessary equipmentand and add the needed vendors getting on board
Then there's the issue of engine supply - Packard was doing the best they could keeping up with current demand, would an American Mossie production line push them behind on current orders?

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## Ovod (Aug 14, 2021)

pinehilljoe said:


> The not-invented here, and the lobbies could never be overcome. Remember Curtis-Wright was the largest company in the USA at the time, bigger than GM. Curtis didnt build the P-61 but with that much money in the industry, the US wasnt going to license an aircraft. The only designs licensed in any number that I can think of were the DH-4, Canberra and Harrier, planes that were superior or unique.



The US also license-produced many different jet engine designs from the UK, plus I or 2 designs from France as well. Not to mention, the Packard Merlin.


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## Ovod (Aug 14, 2021)

In any case was "night-fighting", and the P-61, all that crucial to USAAF activities in the last year or 2 of the European war?


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## Trilisser (Aug 14, 2021)

Shortround6: Just compare the Hercules with the R-2600. The latter was some 10 % larger, yet topped at 1900 hp while the Hurcules delivered 2000 + hp in a more compact package with better fuel economy. Worth noting is that the Hercules and Centaurus matched the power of equivalent Americans (R-2600 and R-3350) with 100/130 while the latter required 115/145. Which is an indication of a very significant advantage. 

As for cylinder head temperatures, e.g.the Centaurus V allowed a maximum continuous CHT of 300 degrees C. An R-3350 as in the AD-4 allowed 245 degrees C. The implication is very significant as the cooling airflow requirements are lower higher the allowed CHT is. And cooling drag thus lower. 

And as for the copper-alloyed heads, even NACA recommended them for air-cooled engines. 

As for the "mechanical complexity, just compare the parts count of the valve gear Mercury vs. Perseus.


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## drgondog (Aug 14, 2021)

GrauGeist said:


> The US M2 20mm was problematic and wasn't adopted as a primary weapon except for the P-61 and F6F-5N.


Dave - IIRC the primary issue with the license based Hispano was a combination of headspace and ammunition issues - but nevertheless installed on P-38s also as well as F4U-1C. Had the P-51F been produced (as an interceptor) it likely would have had the Olds 20mm as a four gun battery.

That said, the AAF also killed the 2x20m, 2x50cal requirement for the CAC (NA-107 P-51E, then P-51D-5), for Australian manufacturing.

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## swampyankee (Aug 14, 2021)

Wooden structures in large aircraft by the CAA due to some airliner crashes caused by failure of wooden components. I suspect that a plan to build Mosquitoes in the US would result in the companies no-bidding.


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## pbehn (Aug 14, 2021)

Reluctant Poster said:


> That only lasted about a month before Donitz ordered the Uboats to remain submerged during the day and only surface at night to recharge the batteries.
> Note that the British introduced rockets shortly after the order to fight it out on the surface. A swordfish was the first aircraft to lanch a British rocket in anger sinking U 752 on May 23 1943.


I thought they mounted "escorts" to bring submarines in and take them out across the bay of Biscay


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## Shortround6 (Aug 14, 2021)

Shortround6 said:


> . Compare a Bristol radial to an equivalent P & W or Wright radial. And by equivalent I mean about the same size and *about the same year of production*.





Trilisser said:


> Shortround6: Just compare the Hercules with the R-2600. The latter was some 10 % larger, yet topped at 1900 hp while the Hurcules delivered 2000 + hp in a more compact package with better fuel economy.



See bolded part of the 1st quote. They were building 1700hp R-2600s in 1941. They built about 1000 of the 1900hp version (pretty much a whole new engine) in 1943. 
Want to tell us when the 2000hp Hercules showed up?? 
Was it the Hercules 230 of 1946-47? 

I know that Bristol got some very good power outputs out of the Hercules and Centaurus but most of these high power levels were post war (and a few into the 1950s) and after a lot more development work was done. Wright pretty much stopped development of the R-2600 in 1944/45(if not in 1943?) . Production stopped for military R-2600 engines in late 1945 and commercial R-2600 engines stopped in 1946. 

I would be very interested to see the fuel consumption figures. I will tell you that the wiki figure for the R-3350 is total hogwash, No air cooled radial used 0.38lbs per HP hour at take-off rating. The British did make some excellent cowling post war. Unless the fuel consumption figure is tied to a power output (and maybe even altitude) it is useless.

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## Shortround6 (Aug 14, 2021)

swampyankee said:


> Wooden structures in large aircraft by the CAA due to some airliner crashes caused by failure of wooden components. I suspect that a plan to build Mosquitoes in the US would result in the companies no-bidding.


That was for commercial aircraft carrying passengers "for hire".

Something the military was not worried about and in fact the Military did put out some requests for transport aircraft built of non strategic materials, most of which did not end well 
Curtiss C-76 Caravan


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## 33k in the air (Aug 14, 2021)

swampyankee said:


> What would the installed weight of 6 or 8 0.5 in M2 be vs 4 Hispano 20 mm? Consider those 4 Hispano would be the equivalent of 12 0.5 in M2.



To follow up, we can look at the F4U Corsair, normally equipped with 6 .50-cal MGs, but the -1C had 4 20mm cannons.

6 x .50-cal MGs and 2,350 rounds total
4 x 20mm cannons with 880 rounds total

That gives some idea of what switching to four cannons would do to ammunition counts.

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## pbehn (Aug 14, 2021)

swampyankee said:


> What would the installed weight of 6 or 8 0.5 in M2 be vs 4 Hispano 20 mm? Consider those 4 Hispano would be the equivalent of 12 0.5 in M2.


33k posted the weights, you need a lot more 0.5 bullets to have the same firing time as a 20mm cannon due to the different rates of fire. Cannon were heavier in a plane that was already dangerously overweight on take off with max external fuel. As Drgondog has posted cannon on the Mustang Mk Is fitted with 4 cannon were 10MPH slower, but that also means approximately 10MPH less on cruise settings so around 60 miles less on a 6 hour mission or 30miles less range. The Spitfire was 6-8MPH slower with 2 cannon. I agree with your point about hitting power but 4 or 6 x 0.5" was enough to take on LW fighters without taking on more weight and drag as well as possible issues of cannons working after being at altitude for hours.


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## GrauGeist (Aug 14, 2021)

The F4U-1C was used with good effect in a ground attack role, but the cannons suffered frequent jams plus icing issues above 20,000 feet.

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## wuzak (Aug 14, 2021)

Shortround6 said:


> I will tell you that the wiki figure for the R-3350 is total hogwash, No air cooled radial used 0.38lbs per HP hour at take-off rating. The British did make some excellent cowling post war. Unless the fuel consumption figure is tied to a power output (and maybe even altitude) it is useless.



That may be true of the turbo-compound version.


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## Shortround6 (Aug 14, 2021)

I doubt very highly that was the fuel consumption at take-off. 
One book says that 0.38 lbs/hp/hr was at "cruise" for the turbo compound engine. Cruise is given at later point in the page as 1560hp at 2200rpm at 12,000ft. 
Take-off was 3500hp at 2900rpm using water injection and 13.5lbs of boost (57.5in) 
Dry take-off was 3250hp at 2900rpm using 14.8lbs boost (59.5in) 

Cruise is going to auto lean mixture at least if not manual lean by flight engineer using exhaust temperature gauges. Take-off is going to rich mixture (very rich) unless using water injection, then it is just sort of rich


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## Zipper730 (Aug 15, 2021)

drgondog said:


> The CAS Doctrine which emerged in 1941-42 was to deploy two types of aircraft to support US Army battlefield operations - Fast Attack Bomber (originally A-20) for low/medium level tactical strikes, and Fast Attack Fighter for Recon, Strafing, light bombing and capable of battlefield air superiority. The P-38/F-4 was originally tasked for fast battlefield recon but replaced by the emerging Mustang designs beginning with P-51-NA/F-6.


And this was inspired by the RAF's desert air force?


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## PAT303 (Aug 15, 2021)

33k in the air said:


> To follow up, we can look at the F4U Corsair, normally equipped with 6 .50-cal MGs, but the -1C had 4 20mm cannons.
> 
> 6 x .50-cal MGs and 2,350 rounds total
> 4 x 20mm cannons with 880 rounds total
> ...


That's true but no fighter is going to survive a 2 sec burst of API/SAPI rounds from a Hispano, early on in the war less effective guns with lots of ammo is preferred but once gyro gunsights, better pilot training and experience starts to make a difference it's the 20mm all the way.


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## Zipper730 (Aug 19, 2021)

I was thinking of something regarding the P-47 & P-38's used in the ground-attack role: From what I recall, with P-47's at least, they used a cover group which were generally operating purely as fighters, correct?


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## Admiral Beez (Aug 20, 2021)

Get the Centaurus working earlier and put it on the Typhoon and Tempest from the onset.


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## Reluctant Poster (Aug 20, 2021)

pbehn said:


> I thought they mounted "escorts" to bring submarines in and take them out across the bay of Biscay


Yes flak uboats with multiple guns. A flop. Surface escorts were not tried.


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## Reluctant Poster (Aug 20, 2021)

Shortround6 said:


> That was for commercial aircraft carrying passengers "for hire".
> 
> Something the military was not worried about and in fact the Military did put out some requests for transport aircraft built of non strategic materials, most of which did not end well
> Curtiss C-76 Caravan
> View attachment 637887


Very little that Curtiss built turned out well.

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## Shortround6 (Aug 20, 2021)

Admiral Beez said:


> Get the Centaurus working earlier and put it on the Typhoon and Tempest from the onset.


If you can't make the Hercules in the desired numbers then the Centaurus is a non-starter.


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## Reluctant Poster (Aug 20, 2021)

drgondog said:


> The A-36 Mustang was designed, proposed, and delivered as 'Low Level Attack Aircraft' - It was deployed and highly successful in all low level attack roles including specifically dive bombing and glide bombing - as well as being capable of defending itself. The Air Force did indeed use the A-24/-25 and not happy with inability to defend themselves.
> 
> The CAS Doctrine which emerged in 1941-42 was to deploy two types of aircraft to support US Army battlefield operations - Fast Attack Bomber (originally A-20) for low/medium level tactical strikes, and Fast Attack Fighter for Recon, Strafing, light bombing and capable of battlefield air superiority. The P-38/F-4 was originally tasked for fast battlefield recon but replaced by the emerging Mustang designs beginning with P-51-NA/F-6.
> 
> ...


Lord Cunningham was an Admiral. I belive you mean Arthur Coningham.








Arthur Coningham (RAF officer) - Wikipedia







en.wikipedia.org

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## GrauGeist (Aug 20, 2021)

Reluctant Poster said:


> Very little that Curtiss built turned out well.


Curtiss was a highly successful aircraft manufacturer, especially with maritime aircraft, up through the mid-30's.
The P-36 was, for it's time, one of the top fighter designs of the day.
With the P-40, they should have let the type run through it's natural progression of upgrades and not spend so much time and energy trying to find a spin-off that would have succeeded it, but instead work up a clean sheet design to replace it.
As far as other types, the SOC, C-46, SB2C and SC were solid performers.


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## Reluctant Poster (Aug 20, 2021)

GrauGeist said:


> Curtiss was a highly successful aircraft manufacturer, especially with maritime aircraft, up through the mid-30's.
> The P-36 was, for it's time, one of the top fighter designs of the day.
> With the P-40, they should have let the type run through it's natural progression of upgrades and not spend so much time and energy trying to find a spin-off that would have succeeded it, but instead work up a clean sheet design to replace it.
> As far as other types, the SOC, C-46, SB2C and SC were solid performers.


The C46 and SB2C took a long time to get right. They had terrible reputations early in their careers. The SOC was prewar. The SC took too long to get into service to be of any use. As you note Curtiss was great up to the mid 30s, after that it produced a long line of failures. The list of prototype fighters is unbelievable, each one a flop. It’s no accident that Curtiss stopped building aircraft after WWII.

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## drgondog (Aug 20, 2021)

Reluctant Poster said:


> Lord Cunningham was an Admiral. I belive you mean Arthur Coningham.
> 
> 
> 
> ...


I agree the correction..

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## Zipper730 (Aug 25, 2021)

Thumpalumpacus said:


> The USAAF did sort of realize this and by 1944 most single-engined attack missions were done by fighters, some modded with hard-points. Neither 8th nor 9th AFs used dedicated single-engine bombers (A-24, A-25, etc), no? That's giving up on the concept of "single-engined bomber", and transforming it to "let's stick as much ordnance as we can on this fighter." It's a subtle but clear distinction, to me. The RAF did the same thing around the same timeframe.


I corrected my post, it's weird how a few letters can totally change the meaning of a message.


> The USN _had_ to keep with single-engined-bombers by dint of the carriers not being able to handle, regularly, the twins of the day.


The problem seemed to have to do with two matters.

Engine-out Performance: This actually prevented the F7F-1 from carrier service (I could be wrong here, but by the time they finally got around this problem, the aircraft was obsolete)
Weight: While some carriers like the Midway were rated to 68750 lb., not all the carriers were rated to that. As a result, they often had to design around what average carriers could make do with.
Spot Factor: The more planes you can stuff on a ship, the better in theory.
(I'm not sure why the new format no longer has the ability to make numbered and unnumbered lists, but those are my bread and butter. I know a few other people who love making lists).


> But once they could put rails/racks on Hellcats, they could back down the bomber complement.


The difference between the USN and the USAAF was that the USN still retained their single-engined bombers, though both used fighter bombers.

The term attack when used by the USAAF & USN can be misleading: In the US Army they were basically tactical-bombers, in the USN they were all ship-board bombers (B/SB/TB/BT, etc...) became attack-planes.

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## wuzak (Aug 25, 2021)

Could the XP-54, XP-55 and XP-56 have been improved to become realistic alternatives for conventional fighters?

For the XP-54 I would lose the 37mm cannon, the gun tilting mechanism and replace with 4 x 20mm or 6 x 0.50", all in the nose, of course. Ditch the pressurised cockpit. I think this will save significant weight.

Next, reduce the size to be more like the original proposal (wing span was ~10ft less than the eventual XP-54 IIRC). 

Find a suitable engine. The H-2470 was not going to be a production engine, so what can we use? I think the only real option in the US was a turbocharged V-1710. The question then is whether the weight has been sufficiently to allow for performance around that of a P-38 or P-51.


The XP-55 needs to have the elevator be a lifting surface all the time. My understanding of the system is that the elevator was free floating - it did its own thing when the pilot was not using it for pitching the aircraft. It would need to be larger as well.

More vertical stabiliser area was also required. 

I don't know how much the performance could have been improved, it was already pretty small. With the elevator giving more lift, the wing could have been reduced in span and size. A tidy up the aerodynamics would not hurt either.

The performance of the XP-55 was similar to the later model P40s.


For the XP-56 I think they would need to start again. From scratch. Maybe try for a flying wing, rather than the flying wing with fuselage and fins that it ended up as.


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## nuuumannn (Aug 26, 2021)

Reluctant Poster said:


> I belive you mean Arthur Coningham.



That wiki page eyeroll is slightly incorrect, Coningham's nickname was "Mary", not "Maori". He earned his nickname because "Maa-ree" was how he pronounced the word "Maori" (which is from the term _Tangata Maori_, which literally translates to Ordinary Man, so native New Zealanders are called Maoris by non natives - Tangata being Man; Maori are Tangatawhenua; People of the Land)

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## nuuumannn (Aug 26, 2021)

On the subject of close support in WW2, of which Coningham, in command of the RAF's Desert Air Force and responsible for turning it around, was an advocate, who pioneered forward air control operations using radios to communicate between aircraft and troops on the ground for strike operations in the North African desert, the USAAF had its own close support advocate in Gen Elwood "Pete" Quesada, who also tried out the use of radio comms between ground forces and ground attack aircraft with the Ninth AF. Based in the UK in 1944, he and Coningham had a good working relationship, both working toward the same thing around Overlord, when Coningham was C-in-C of the 2nd Tactical Air Force.

Between the pair of them, these two pretty much defined future close support/interdiction principles applied since the war.









LIEUTENANT GENERAL ELWOOD R. QUESADA


Elwood Quesada was a member of the famous Question Mark endurance crew of 1929. In the first week of January, Second Lieutenant Quesada flew as a crew member with Major Carl Spaatz, Captain Ira Eaker,



www.af.mil













General Elwood Quesada: Air Tactics Innovator and Friend to Ground Troops


During the Normandy campaign of 1944, one air commander gave the ground troops the close support they wanted. That man was General Elwood “Pete” Quesada.




www.warhistoryonline.com

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## P-39 Expert (Aug 26, 2021)

wuzak said:


> Could the XP-54, XP-55 and XP-56 have been improved to become realistic alternatives for conventional fighters?
> 
> For the XP-54 I would lose the 37mm cannon, the gun tilting mechanism and replace with 4 x 20mm or 6 x 0.50", all in the nose, of course. Ditch the pressurised cockpit. I think this will save significant weight.
> 
> ...


The two stage Allison -93 engine could have been used.


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## wuzak (Aug 30, 2021)

P-39 Expert said:


> The two stage Allison -93 engine could have been used.



In which one?

I presume you mean the XP-54, since the XP-55 doesn't have room for the 2nd stage and the XP-56 was a turd?

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## wuzak (Aug 30, 2021)

Regarding the P-40, could the circular engine radiators for the V-1710 versions be relocated to the leading edge of the wing, perhaps ahead of the landing gear housing? Tidy up the lower forward fuselage.

Picture thanks to nuuumannn











Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)


Last time I tried to make ice, I ended up burning it I wonder if I turned the dial the wrong way? Check the ingredients. If you added two oxygens to one carbon and then chilled, you'll get something else entirely!



ww2aircraft.net


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## Reluctant Poster (Aug 30, 2021)

wuzak said:


> Regarding the P-40, could the circular engine radiators for the V-1710 versions be relocated to the leading edge of the wing, perhaps ahead of the landing gear housing? Tidy up the lower forward fuselage.
> 
> Picture thanks to nuuumannn
> View attachment 639851
> ...


The circular radiators were an obsolete design. Curtiss should have moved to the vastly superior extended surface radiators (fin and tube, like your car radiator) as used by Rolls Royce. I believe Merlin powered P-40s did use extended surface radiators.


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## P-39 Expert (Aug 30, 2021)

Reluctant Poster said:


> The circular radiators were an obsolete design. Curtiss should have moved to the vastly superior extended surface radiators (fin and tube, like your car radiator) as used by Rolls Royce. I believe Merlin powered P-40s did use extended surface radiators.


Agee, a rectangular coolant radiator and a rectangular oil radiator may have reduced the frontal area enough that the radiator housing didn't extend below the lower wing.


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## Admiral Beez (Sep 22, 2021)

MiTasol said:


> Centaurus production started in 1942 so it would be difficult to _send four squadrons to Malaya in early 1941, eight more by October 1941._


Forget the Centaurus then. The Typhoon needs just two improvements.... make the Sabre reliable and more available, and strengthen the tail. We should be able to get some to Malaya in 1941.


Admiral Beez said:


> Hawker Typhoon. Fix the tail at the onset, get a reliable and mass produced Sabre Send four squadrons to Malaya in early 1941, eight more by October 1941.


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## wuzak (Sep 22, 2021)

Admiral Beez said:


> Forget the Centaurus then. The Typhoon needs just two improvements.... make the Sabre reliable and more available, and strengthen the tail. We should be able to get some to Malaya in 1941.



Highly doubtful.


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## fastmongrel (Sep 23, 2021)

In 1941 the Sabre is an immature very labour and spares intensive engine at the end of a very long logistics tail. Until English Electric take over Napier and move production to a new factory you are not going to get reliable engines.

Napier's factory was a Victorian relic incapable of producing mass production engines with interchangeable parts. For 1941 it's Merlin's or a US round engine.

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## MikeMeech (Sep 24, 2021)

fastmongrel said:


> In 1941 the Sabre is an immature very labour and spares intensive engine at the end of a very long logistics tail. Until English Electric take over Napier and move production to a new factory you are not going to get reliable engines.
> 
> Napier's factory was a Victorian relic incapable of producing mass production engines with interchangeable parts. For 1941 it's Merlin's or a US round engine.


Hi
As far as I know Napier's factory was built on land purchased in 1903 and 1904 at Acton, west of London, after they had out grown their Lambeth site, to build automobile engines. Therefore it would less than 40 years old in WW2 and not 'Victorian'. For mass production of the Sabre MAP built a new factory in Liverpool, initially it was to be managed by Napiers but to re-organize production it ended up being 'taken over' by English Electric at the end of 1942 which was 'encouraged' by MAP.

Mike

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## fastmongrel (Sep 24, 2021)

MikeMeech said:


> Hi
> As far as I know Napier's factory was built on land purchased in 1903 and 1904 at Acton, west of London, after they had out grown their Lambeth site, to build automobile engines. Therefore it would less than 40 years old in WW2 and not 'Victorian'. For mass production of the Sabre MAP built a new factory in Liverpool, initially it was to be managed by Napiers but to re-organize production it ended up being 'taken over' by English Electric at the end of 1942 which was 'encouraged' by MAP.
> 
> Mike


Some of the machinery at Napier's was Victorian. It wasn't a big factory building it was a collection of relativity small buildings set around a cobbled yard. One of the problems with the sleeve valves they were machined in one building and then taken on a wooden hand cart to another building to be hardened then back by hand cart to the assembly building. So the sleeve valves which had to be perfectly round were bumped across a cobbled yard at least twice. 

Napier's factory was a Victorian style small engineering works, the sort that was in common use in the mid 19th Century. There was no production line it was craftsman style production.

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## SaparotRob (Sep 24, 2021)

fastmongrel said:


> Some of the machinery at Napier's was Victorian. It wasn't a big factory building it was a collection of relativity small buildings set around a cobbled yard. One of the problems with the sleeve valves they were machined in one building and then taken on a wooden hand cart to another building to be hardened then back by hand cart to the assembly building. So the sleeve valves which had to be perfectly round were bumped across a cobbled yard at least twice.
> 
> Napier's factory was a Victorian style small engineering works, the sort that was in common use in the mid 19th Century. There was no production line it was craftsman style production.


That reminded me of something that happened when I worked for a medical device manufacturer. We had a "gopher" (go for this, go for that). He was somewhat intellectually challenged. He was sent to pick up a highly machined (and long) component from a supplier. He decided to help by not taking a taxi to save the company money and walked the mile or two back. He was dragging one end up and down the streets of Manhatten back to our factory. He was so proud.


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## Milosh (Sep 24, 2021)

fastmongrel said:


> they were machined in one building and then taken on a wooden hand cart to another building to be hardened then back by hand cart to the assembly building.


Going across would be no problem I would think as they hadn't been machined yet.

How would bumping across the cobbles effect the machined pieced?


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## GrauGeist (Sep 24, 2021)

It's possible that the valves were at least packed in straw or set in racks for the journey, but my first thought was what a time consuming process.
Load a batch, wheel across to the other side, unload.
Conduct the hardening.
Load up the finished valves, wheel back to the plant.
Unload and continue with the assembly process.
For custom work, that would be a non-issue, but for assembly line efficiency, that's a critical bottle-neck.

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## pbehn (Sep 24, 2021)

GrauGeist said:


> It's possible that the valves were at least packed in straw or set in racks for the journey, but my first thought was what a time consuming process.
> Load a batch, wheel across to the other side, unload.
> Conduct the hardening.
> Load up the finished valves, wheel back to the plant.
> ...


In terms of production it can be done but as you say is very labour intensive and inefficient. The real problems start when you have a quality issue, which Napiers had. Trying to pin down what was done to which sleeve valve to cause the problem and then determine which others are or maybe affected is a huge and maybe impossible task.

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## swampyankee (Sep 24, 2021)

Milosh said:


> Going across would be no problem I would think as they hadn't been machined yet.
> 
> How would bumping across the cobbles effect the machined pieced?


The sleeves were very thin. Indeed, I've read they needed to be stored vertically because they'd become too out-of-round to use if they were laid on their sides.

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## don4331 (Sep 24, 2021)

The problem with Napier's sleeve valves starts with the inner and outer surfaces *must* be concentric (or relatively close) i.e. you can't have thick wall on one side and thin on the other. The craftsmen building the prototypes/initial production could hold the tolerances but when they brought in lower skilled individuals for volume production, they weren't able to maintain it. The solution to the problem is to finish the inner surface using a "center-less" operation - in practise, center-less grinding machines were used at the expensive of American valve being able to be produced. Center-less finishing ensures constant wall thickness.

Then they laid the cylinders 5 or 6 high on a hand cart with steel wheels that was pushed over cobbles from one building to next. Somewhere there's a picture of a "gopher" driving tractor pulling a cart of cylinders. The result was the bottom cylinders were no longer round by the time they got to the heat treatment shop. And oval sleeve valves don't work well. As 

 swampyankee
says they needed to be transport vertically.

And you have the standard production line issues: bored employees, rushed production schedules, staff not understanding what they are doing that lead to quality issues.
Rolls Royce Vulture rod bearing issues were example - they needed to be tightened just to certain torque aka tight-enuf. But employees, on the line, gave it an additional tug, just to ensure it wouldn't come loose. The result was the bolts were over-stressed and failed in service. RR changed from measuring tightness via torque to measuring bolt stretch with a no/no-go gage - replacing over tightened bolts and the problem when away. 'Course, by that time, the Vulture already had a "reputation". And it needed a wholesale redesign to be a 2,500hp engine on 100 octane, which RR didn't have time for just then.

Lastly, you need to keep the f🤬 Rolls-Royce technicians away. Their "tweaking" of the Napier "black box" to give "a little" more boost, tended to blow up otherwise fine Sabres. They did make Napier look bad, but at the cost of RAF pilots.

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## MikeMeech (Sep 24, 2021)

fastmongrel said:


> Some of the machinery at Napier's was Victorian. It wasn't a big factory building it was a collection of relativity small buildings set around a cobbled yard. One of the problems with the sleeve valves they were machined in one building and then taken on a wooden hand cart to another building to be hardened then back by hand cart to the assembly building. So the sleeve valves which had to be perfectly round were bumped across a cobbled yard at least twice.
> 
> Napier's factory was a Victorian style small engineering works, the sort that was in common use in the mid 19th Century. There was no production line it was craftsman style production.


Hi
For interest an image of part of Napier's Acton factory during 1924. The engine is the Napier Lion, in 1927 the production of this type was around 50 per month. This was a 'small' factory in WW2 terms which is why MAP 'supplied' the factory at Liverpool aiming to supply 2000 Sabre's per year. Machine tools were also bought in the USA for this and other factories, on top of British machine tools.






Mike

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## wuzak (Sep 25, 2021)

don4331 said:


> Rolls Royce Vulture rod bearing issues were example - they needed to be tightened just to certain torque aka tight-enuf. But employees, on the line, gave it an additional tug, just to ensure it wouldn't come loose. The result was the bolts were over-stressed and failed in service. RR changed from measuring tightness via torque to measuring bolt stretch with a no/no-go gage - replacing over tightened bolts and the problem when away. 'Course, by that time, the Vulture already had a "reputation". And it needed a wholesale redesign to be a 2,500hp engine on 100 octane, which RR didn't have time for just then.



I find it hard to believe that a trained assembly technician would over-torque bolts just because they felt like it. They would have used torque wrenches to apply the correct torque.

The original Vulture big end had only two bolts on one side of the rod. The other side was kept in place with a transverse pin. This design was problematic.

This was redesigned to use 4 bolts - 2 long on one side and 2 short on the other. These did not allow the normal pre-tensioning to Rolls-Royce's normal standards. This design still had bearing issues.

Had the Vulture continued, the master rod would have been a new design, which may have been done but not made it to production.




don4331 said:


> Lastly, you need to keep the f🤬 Rolls-Royce technicians away. Their "tweaking" of the Napier "black box" to give "a little" more boost, tended to blow up otherwise fine Sabres. They did make Napier look bad, but at the cost of RAF pilots.



Rolls-Royce technicians? Do you mean RAF technicians, who were used to working on Merlins?

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## don4331 (Sep 25, 2021)

wuzak said:


> I find it hard to believe that a trained assembly technician would over-torque bolts just because they felt like it. They would have used torque wrenches to apply the correct torque.
> 
> This was redesigned to use 4 bolts - 2 long on one side and 2 short on the other. These did not allow the normal pre-tensioning to Rolls-Royce's normal standards. This design still had bearing issues.


If you believe the assembly line workers are all there because they want to do a perfect job, you've never worked in a manufacturing environment. For most people, it was a job, not a career. And when worker were putting in 6 x 12 hour + 8 on Sunday for an 80 hour week - week after week, the job gets old real fast. And with 100% employment, you can't fire people, because you can't replace them.

And it doesn't have to be deliberate - 2 individuals competing to see who can get their 3 rods done fastest - so, you're overshooting the torque wrench because you're pulling so fast that you don't stop right when the torque wrench clicks. And we aren't even discussing that the individuals have foregone the correct tightening sequence which can result in warped parts.

The long and short bolt of the Vulture rod *are* the problem. The issue with pre-tensioning is the longer bolts need to be tightened to a higher value than shorter so that bolt stretch under load is equal. Any designer/manufacturers prefers that all 4 be the same length, so they can be tightened the same. The easy to do mistake of tightening the short bolts to the long bolts value results in the short bolts being over-tighten and failing in service. Hence, the implementation of a gauge to check bolt stretch.


wuzak said:


> Rolls-Royce technicians? Do you mean RAF technicians, who were used to working on Merlins?


Manufacturers representives, might be better name for them; individuals for whom RR paid their checks, and knew better but were being malicious. The RAF fitters weren't the worst problem.

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## wuzak (Sep 26, 2021)

don4331 said:


> If you believe the assembly line workers are all there because they want to do a perfect job, you've never worked in a manufacturing environment. For most people, it was a job, not a career. And when worker were putting in 6 x 12 hour + 8 on Sunday for an 80 hour week - week after week, the job gets old real fast. And with 100% employment, you can't fire people, because you can't replace them.
> 
> And it doesn't have to be deliberate - 2 individuals competing to see who can get their 3 rods done fastest - so, you're overshooting the torque wrench because you're pulling so fast that you don't stop right when the torque wrench clicks. And we aren't even discussing that the individuals have foregone the correct tightening sequence which can result in warped parts.
> 
> The long and short bolt of the Vulture rod *are* the problem. The issue with pre-tensioning is the longer bolts need to be tightened to a higher value than shorter so that bolt stretch under load is equal. Any designer/manufacturers prefers that all 4 be the same length, so they can be tightened the same. The easy to do mistake of tightening the short bolts to the long bolts value results in the short bolts being over-tighten and failing in service. Hence, the implementation of a gauge to check bolt stretch.



The design of the joint was the problem, not assembly errors.

When did Rolls-Royce start using bolt stretch to measure pre-tension?




don4331 said:


> Manufacturers representives, might be better name for them; individuals for whom RR paid their checks, and knew better but were being malicious. The RAF fitters weren't the worst problem.



Do you have specific instances that you can share?

That sounds like a conspiracy theory, an excuse to explain the poor reliability of the Sabre in its early service.


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## MikeMeech (Sep 26, 2021)

GrauGeist said:


> It's possible that the valves were at least packed in straw or set in racks for the journey, but my first thought was what a time consuming process.
> Load a batch, wheel across to the other side, unload.
> Conduct the hardening.
> Load up the finished valves, wheel back to the plant.
> ...


Hi
For interest, here is a short overview (from 'British Piston Aero-Engines and their Aircraft' by Alec Lumsden, p.175) of Sabre sleeve valve problems and Bristol's involvement:








Also reference to Napier's and the Sabre, with Hives (Rolls-Royce) commercial worries about Napier (from 'Industry and Air Power, The Expansion of British Aircraft Production, 1935-1941' by Sabastian Ritchie, p.140):




Also from an on-line source the Acton factory of Napier from the air:





Mike

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## don4331 (Sep 26, 2021)

wuzak said:


> The design of the joint was the problem, not assembly errors.
> 
> When did Rolls-Royce start using bolt stretch to measure pre-tension?


RRHT No. 16 p.139 - special care being taken during assembly to obtain the correct stretch of the bolt during tightening by means of a direct measurement of sttetch of the bolt

p.142 The condition was slightly improved by a rigid tightening order.


wuzak said:


> Do you have specific instances that you can share?
> 
> That sounds like a conspiracy theory, an excuse to explain the poor reliability of the Sabre in its early service.


Looking for the reference for the Sabre mods. But it was late Sabres operating with 2nd TAF.

Why is it so hard to accept that workers RR added to during the war were human?

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## wuzak (Sep 26, 2021)

don4331 said:


> Looking for the reference for the Sabre mods. But it was late Sabres operating with 2nd TAF.
> 
> Why is it so hard to accept that workers RR added to during the war were human?



Being "human" implies a mistake or mistakes.

But you said they were being "malicious" - which is a deliberate act.



don4331 said:


> Manufacturers representives, might be better name for them; individuals for whom RR paid their checks, and knew better but were being *malicious*.

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## Thumpalumpacus (Sep 26, 2021)

wuzak said:


> But you said they were being "malicious" - which is not a deliberate act.



This appears to be a typo?


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## wuzak (Sep 27, 2021)

Thumpalumpacus said:


> This appears to be a typo?



Thanks. Fixed.

Should have read "But you said they were being "malicious" - which is a deliberate act."

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## Reluctant Poster (Sep 27, 2021)

don4331 said:


> The problem with Napier's sleeve valves starts with the inner and outer surfaces *must* be concentric (or relatively close) i.e. you can't have thick wall on one side and thin on the other. The craftsmen building the prototypes/initial production could hold the tolerances but when they brought in lower skilled individuals for volume production, they weren't able to maintain it. The solution to the problem is to finish the inner surface using a "center-less" operation - in practise, center-less grinding machines were used at the expensive of American valve being able to be produced. Center-less finishing ensures constant wall thickness.
> 
> Then they laid the cylinders 5 or 6 high on a hand cart with steel wheels that was pushed over cobbles from one building to next. Somewhere there's a picture of a "gopher" driving tractor pulling a cart of cylinders. The result was the bottom cylinders were no longer round by the time they got to the heat treatment shop. And oval sleeve valves don't work well. As
> 
> ...


Is this a true story or urban legend? I have never seen a factual account.


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## Reluctant Poster (Sep 27, 2021)

Reluctant Poster said:


> I the Rolls Royce story true or urban legend? I have never seen a factual account.


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## DarrenW (Oct 2, 2021)

P-39 Expert said:


> Yes I really do wonder. Half of them went to the Soviets where they won the war and the other half were used as trainers here. And ANY combat plane would be a major step up from an AT-6 Texan.
> 
> You can keep grasping for any straw and rumor to somehow make the P-39 a deathtrap, but in reality it was a very serviceable combat plane. Do you consider the F6F Hellcat to be a good plane? Scourge of the Japanese and kings of the Pacific. Shot down more Japanese aircraft than any other plane. Look at the attached graph (wwiiaircraftperformance.org) with P-39N performance overlayed in red. Pretty competitive, no? And consider that the P-39N was out of production before the Hellcat had it's first combat with the USN.



The graph you posted displays the performance of the F6F-3 in a "combat" condition, meaning with underwing bomb racks and fuselage bomb shackles. The points you added display the speed of the P-39N in a "clean" condition with no racks or pylons mounted. Not really an apples to apples comparison. 

Sure the P-39N had a decent enough top speed and climb rate but there are other qualities needed in a fighter in order to make it competitive in it's designed role and area of operation.


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## P-39 Expert (Oct 2, 2021)

The P-39N only had one external store, a belly shackle. Deduct 10mph for the shackle with braces. Still very comparable to the F6F in speed and very much better in climb.


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## DarrenW (Oct 2, 2021)

P-39 Expert said:


> The P-39N only had one external store, a belly shackle. Deduct 10mph for the shackle with braces. Still very comparable to the F6F in speed and very much better in climb.


How did you come up with that speed loss figure? But even if that's true at the end of the day what does that really get you? It had a mediocre bomb carrying capability and range suffered even more because it couldn't carry a drop tank at the same time to help overcome the extra drag and weight of the bomb being carried.


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## DerAdlerIstGelandet (Oct 2, 2021)

DarrenW said:


> *How did you come up with that speed loss figure? *But even if that's true at the end of the day what does that really get you? It had a mediocre bomb carrying capability and range suffered even more because it couldn't carry a drop tank at the same time to help overcome the extra drag and weight of the bomb being carried.




*



*

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## GrauGeist (Oct 2, 2021)

P-39 Expert said:


> Still very comparable to the F6F in speed and very much better in climb.

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## pbehn (Oct 2, 2021)

DarrenW said:


> How did you come up with that speed loss figure?


Its in this test P-39 Performance Tests about 9 or 10 MPH depending on engine RPM

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## DarrenW (Oct 2, 2021)

pbehn said:


> Its in this test P-39 Performance Tests about 9 or 10 MPH depending on engine RPM


Thanks for the verification....

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## SaparotRob (Oct 2, 2021)

After scoping out 

 DarrenW
avatar, I watched a video about the Hellcat v. Zero. It stated that the Hellcat had the highest kill ratio of any fighter of WW 2. Is that correct?


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## Greg Boeser (Oct 2, 2021)

DarrenW said:


> The graph you posted displays the performance of the F6F-3 in a "combat" condition, meaning with underwing bomb racks and fuselage bomb shackles. The points you added display the speed of the P-39N in a "clean" condition with no racks or pylons mounted. Not really an apples to apples comparison.
> 
> Sure the P-39N had a decent enough top speed and climb rate but there are other qualities needed in a fighter in order to make it competitive in it's designed role and area of operation.


EEDeeoot! No poken das schleepink Groundhog!!!

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## Thumpalumpacus (Oct 2, 2021)

Damn it, where's my mallet?

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## DarrenW (Oct 2, 2021)

SaparotRob said:


> After scoping out
> 
> DarrenW
> avatar, I watched a video about the Hellcat v. Zero. It stated that the Hellcat had the highest kill ratio of any fighter of WW 2. Is that correct?


I would say it had the highest 'official' kill ratio of any American fighter, when flown by American pilots. And like all claims we can debate for centuries about the true validity of said claims but that's a different discussion all together. 

Some would say the FM-2 Wildcat has it beat but if you group this variant with all other Wildcats produced (as people sometimes do) it has an official ratio that was less than that of the Hellcat.

Interestingly, the Fins were far more successful flying the Brewster Buffalo than the US Navy and racked up a very respectable kill ratio against the Soviets (greater than that of the Hellcat), but again it was an American fighter flown by Finnish pilots so it's not in the same category as the Hellcat.

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## Thumpalumpacus (Oct 2, 2021)

IIRC the claimed ratio was 18:1 for the Hellcat. I'm skeptical. It was certainly the highest _claimed_ ratio. That and four dollars will get you a cup of mud at Starbucks.

I doubt Japanese loss documentation would back that up except for perhaps the special instance of the Philippine Sea battle.

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## SaparotRob (Oct 2, 2021)

I would've thought the BF-109 would've had the highest score. When the Zero was a dominant fighter, it didn't face as many opponents. 
I'm taking your comment about the Buffalo as a win. 
I'm from L.I. Go Grumman!

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## SaparotRob (Oct 2, 2021)

BTW, The B-17B is my all time favorite.

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## SaparotRob (Oct 2, 2021)

Greg Boeser said:


> EEDeeoot! No poken das schleepink Groundhog!!!


Someone please add a like. Clean sweep!

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## GrauGeist (Oct 2, 2021)

Thumpalumpacus said:


> IIRC the claimed ratio was 18:1 for the Hellcat. I'm skeptical. It was certainly the highest _claimed_ ratio. That and four dollars will get you a cup of mud at Starbucks.
> 
> I doubt Japanese loss documentation would back that up except for perhaps the special instance of the Philippine Sea battle.


Going by memory (I know, scary...), the F6F's loss to the Japanese were in the low hundreds whike they accrued over 5,000 claims, so the kill to loss ratio was fairly substantial.
I know the FM2 Wildcat had a high tally, but it's usually lumped in with the F4F, which waters down it K2L ratio, but as I recall (again, memory thing, be warned) the FM2 itself was not far from the F6F's.

In regards to the Bf109's K2L ratio, it was not as high as one may think. Yes, the type accounted for a great many Allied aircraft downed, but it also suffered a considerable amount of losses, lowering the ratio substantially.

*addendum*
I beleive the kill tally for the F6F in U.S. service typically quoted, is mainly focused on victories over Japanese opponents. 
The F6F in USN service also gained victories against Luftwaffe aircraft in Europe, too.
While the number isn't nearly as large, there were no losses to the Luftwaffe during their brief European operation.

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## Spindash64 (Aug 2, 2022)

Ki-61-II: install a larger fuel tank behind the cockpit rather than using lead weights, possibly armored. This wouldn't directly improve performance, but it would at least provide better endurance for the increased weight rather than getting absolutely nothing.

Of course, just ditching the Ha-140 altogether for the Ha-112 worked out just as well for the Japanese.

On the topic of the the Kinsei, from a design standpoint, the Japanese should have really switched to this engine over the Sakae much earlier and give the Zeroes a desperately needed power increase. This would have also freed up manpower at Nakajima to work on the Homare, potentially letting it reach desired reliability and power early enough to allow the A7M1 to reach production. I'm aware that switching engines isn't a small feat, but the Sakae's power output was simply unacceptable in comparison to alternatives, and the Kinsei was almost the exact same weight and diameter, thus making it much less painful to adapt a number of aircraft to the new powerplant than it would be for some other engine installations.


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## gumbyk (Aug 2, 2022)

Spindash64 said:


> Ki-61-II: install a larger fuel tank behind the cockpit rather than using lead weights, possibly armored. This wouldn't directly improve performance, but it would at least provide better endurance for the increased weight rather than getting absolutely nothing.
> 
> Of course, just ditching the Ha-140 altogether for the Ha-112 worked out just as well for the Japanese.
> 
> On the topic of the the Kinsei, from a design standpoint, the Japanese should have really switched to this engine over the Sakae much earlier and give the Zeroes a desperately needed power increase. This would have also freed up manpower at Nakajima to work on the Homare, potentially letting it reach desired reliability and power early enough to allow the A7M1 to reach production. I'm aware that switching engines isn't a small feat, but the Sakae's power output was simply unacceptable in comparison to alternatives, and the Kinsei was almost the exact same weight and diameter, thus making it much less painful to adapt a number of aircraft to the new powerplant than it would be for some other engine installations.


Lead weights are used for ballast to get centre of gravity in the correct place. If you put in fuel tanks in there instead, once the tank is empty you're back to having a C of G issue.

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## Spindash64 (Aug 3, 2022)

Spindash64 said:


> Ki-61-II: install a larger fuel tank behind the cockpit rather than using lead weights, possibly armored. This wouldn't directly improve performance, but it would at least provide better endurance for the increased weight rather than getting absolutely nothing.
> 
> Of course, just ditching the Ha-140 altogether for the Ha-112 worked out just as well for the Japanese.
> 
> On the topic of the the Kinsei, from a design standpoint, the Japanese should have really switched to this engine over the Sakae much earlier and give the Zeroes a desperately needed power increase. This would have also freed up manpower at Nakajima to work on the Homare, potentially letting it reach desired reliability and power early enough to allow the A7M1 to reach production. I'm aware that switching engines isn't a small feat, but the Sakae's power output was simply unacceptable in comparison to alternatives, and the Kinsei was almost the exact same weight, thus making it much less painful to adapt a number of aircraft to the new powerplant than it would be for some other engine installations.





gumbyk said:


> Lead weights are used for ballast to get centre of gravity in the correct place. If you put in fuel tanks in there instead, once the tank is empty you're back to having a C of G issue.


I'm aware. But at least USE the weight for something. Even if it's a bunch of armor plates protecting nothing in particular, it's more useful than nothing. They could also sidestep this by reducing the fuel capacity in the wing tanks slightly and making the new fuselage tank much larger

My point is, if you're adding dead weight to your aircraft for an engine that hasn't had all the kinks worked out, you already flunked up.

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## gumbyk (Aug 3, 2022)

Spindash64 said:


> I'm aware. But at least USE the weight for something. Even if it's a bunch of armor plates protecting nothing in particular, it's more useful than nothing. They could also sidestep this by reducing the fuel capacity in the wing tanks slightly and making the new fuselage tank much larger
> 
> My point is, if you're adding dead weight to your aircraft for an engine that hasn't had all the kinks worked out, you already flunked up.


Still not gonna work. Ballast is put as far back as possible, to minimise the amount of weight needed. Where you might need 100 lbs of weigh in the tail, you could need 3 or 4 times that much as armour plate.
A larger fuel tank behind the pilot (and behind the C of G) will only serve to make the problem worse. Fuel tanks in the wings were placed there because they were ale to put them at the C of G and minimise changes as the fuel burnt off.

Everything in aircraft design is compromise. I doubt that the addition of ballast was the first or only solution considered. 
Sometimes 'dead' weight is the best solution, short of a complete re-design.

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## FLYBOYJ (Aug 3, 2022)

Spindash64 said:


> I'm aware. But at least USE the weight for something. *Even if it's a bunch of armor plates protecting nothing in particular, it's more useful than nothing. *They could also sidestep this by reducing the fuel capacity in the wing tanks slightly and making the new fuselage tank much larger
> 
> My point is, if you're adding dead weight to your aircraft for an engine that hasn't had all the kinks worked out, you already flunked up.


I don't know if you know anything about weight and balance but you can't effectively start adding weight, (be it ballast or armor plate) unless that weight can be installed along the "arm" where the C/G can be maintained within the C/G envelope and can be supported structurally within the aircraft. The other key is to install that ballast in a place within the arm so you use the least amount of weight possible. Using fuel to keep and aircraft within a C/G envelope is dangerous unless there is a method to burn off or transfer fuel in such a manner that the C/G envelope can be maintained. You also have to consider what is going to happen to the C/G after any armament is expelled.

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## GrauGeist (Aug 3, 2022)

Well, if you removed the nose armor...oh, wait.

Never mind...

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## Kilkenny (Aug 3, 2022)

Spindash64 said:


> Ki-61-II: install a larger fuel tank behind the cockpit rather than using lead weights, possibly armored. This wouldn't directly improve performance, but it would at least provide better endurance for the increased weight rather than getting absolutely nothing.
> 
> Of course, just ditching the Ha-140 altogether for the Ha-112 worked out just as well for the Japanese.
> 
> On the topic of the the Kinsei, from a design standpoint, the Japanese should have really switched to this engine over the Sakae much earlier and give the Zeroes a desperately needed power increase. This would have also freed up manpower at Nakajima to work on the Homare, potentially letting it reach desired reliability and power early enough to allow the A7M1 to reach production. I'm aware that switching engines isn't a small feat, but the Sakae's power output was simply unacceptable in comparison to alternatives, and the Kinsei was almost the exact same weight and diameter, thus making it much less painful to adapt a number of aircraft to the new powerplant than it would be for some other engine installations.


Agree totally. The Sakae was a great engine; but just didn't have the same development potential as the Kinsei. If Japan had produced the A6M8 in 1942 (and put in more armor and fuel tank protection--- possibly at the expense of range), the Zero would have been competitive at least by the time the A7M went into service (ideally around mid-1944).


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## Thumpalumpacus (Aug 3, 2022)

GrauGeist said:


> Well, if you removed the nose armor...oh, wait.
> 
> Never mind...









Your coat's on the rack immediately right of the door.

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## MiTasol (Aug 3, 2022)

And there is a sinkhole waiting just where you front step used to be

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## Thumpalumpacus (Aug 3, 2022)

MiTasol said:


> And there is a sinkhole waiting just where you front step used to be



Why'dya say anything?!

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## Spindash64 (Aug 4, 2022)

FLYBOYJ said:


> I don't know if you know anything about weight and balance but you can't effectively start adding weight, (be it ballast or armor plate) unless that weight can be installed along the "arm" where the C/G can be maintained within the C/G envelope and can be supported structurally within the aircraft. The other key is to install that ballast in a place within the arm so you use the least amount of weight possible. Using fuel to keep and aircraft within a C/G envelope is dangerous unless there is a method to burn off or transfer fuel in such a manner that the C/G envelope can be maintained. You also have to consider what is going to happen to the C/G after any armament is expelled.


I get that there's only so much that you can do in that regard, and I get that I was acting like it's way simpler to fix CoG issues than it actually is. But generally, when you're forced to add ballast to an engineering project that desires low weight, you need to ask if the performance gains being made are worth it. IF the Ha-140 were a mature engine, and had acceptable reliability, then maybe it would have been worth the risk, as a 1,500hp engine with low frontal area. But it was not mature, and as such, there was little room for pilots to USE that extra power even if the aircraft DIDN'T need to make massive sacrifices in order to house the engine. So in practice, the only real benefit of the Ki-61-II was in maximum level speed, which was still only decent, and it suffered in maneuverability, reliability, and received little benefit to climb rate, due to the increase in weight balancing out the power gains.

The Ki-100 is the direction a Hien upgrade should have been pushed towards all along: while the Kinsei wasn't a perfect engine either, and the frontal area was larger, the weight was more or less comparable to that of the Ha-40 engine, but without the need for a liquid cooling system. Even if we assume a far less mature variant of the Kinsei that was only rated for 1,200hp, the cost in maximum speed would be compensated for by better serviceability and by greater development potential. Quite simply put, Japan should have simply cut its losses with liquid cooled aircraft engines, as the difference in power to weight and frontal area between types was proving to be much smaller than the difference in Japan's ability to manufacture one or the other at a given rated power.

I suppose if I'm going to keep babbling on about Japanese aircraft, I should probably argue that they should have placed a greater priority of placing at least 1 heavy machine gun on the zero by the next major production variant, the Model 32 (A6M3). Pilots had found the ballistics of the current 20mm cannon unwieldy, but it was also apparent that rifle caliber machine guns were woefully underequipped to deal with USN aircraft. I can't find anything suggesting the Type 3 Aircraft machine gun would be available at this time, but in theory, the Navy could have requested a naval variant of the Ho-103 as a stop gap if the Type 3 couldn't be adapted. Yes, these are much heavier guns, on a plane that is meant to be lightweight, but a single Ho-103 or Type 3 mounted in the cowling would offer superior damage against protected aircraft than a pair of rifle caliber machine guns. Depending on when this was implemented, it could arguably be of greater importance than applying armor plate to the Zero, if only because making use of better pilot protection would requires a complete overhaul of the Japanese military's culture and view of the value of a serviceman's life: it doesn't matter if they survive to bail out or ditch, no one will be coming to save them.



I have no idea where I'm even going with this anymore...

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## MiTasol (Aug 4, 2022)

As you have guessed ballast location can be a real problem. 

The simple solution for nose heavy is to fit the ballast as far back as possible meaning on the rear spar of the fin (or inside the rear spar of the fin if a tubular frame - a common fix on aerobatic aircraft) as that requires the absolute minimum of additional weight but it is not that simple. 

Having the ballast weight that far back is great if your actual operating weight or CG only changes a small amount but can quickly get problematic if you have a large weight reduction from fuel and ammo actually on or near the CG. Then the weight needs to be close enough to the CG to keep it in limits and simultaneously far enough away to the CG to keep it in limits.

Modern airliners have it easy. On one hand the CG moves forward as the fuel in the wing burns off as gravity moves the fuel inboard and forward leaving the outer aft portion of the wing empty. To compensate many have ballast tanks in the tail that they can use to move the CG back and forth as required - especially now that load control software takes the calculations out of the airframe drivers hands to optimise/minimise drag.

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## FLYBOYJ (Aug 4, 2022)

Spindash64 said:


> I get that there's only so much that you can do in that regard, and I get that I was acting like it's way simpler to fix CoG issues than it actually is. But generally, when you're forced to add ballast to an engineering project that desires low weight, you need to ask if the performance gains being made are worth it.


Aside from the what you're saying and the poor performance of this engine, there's still a lot of thought and consideration when placing ballast on an aircraft. In some cases ballast placement and the few extra pounds that came along with it made the aircraft perform better. If I recall, the Spitfire Mk IX had almost 90 pounds of ballast in the tail. Now if you can make armor plate work for you as ballast, that's a plus, but it like hoping planets and stars align in your favor.

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## Spindash64 (Aug 5, 2022)

Yeah, in hindsight that was me talking about of my ass. I DO Still argue that, in the case of the Ki-61-II, it was among the little things that added up as red flags to say "This new engine ain't it, chief". If water injection had been developed for the engine, then maybe the available power could have been enough to actually improve the climb rate. But as it stands, even the Ha-40 was a bit temperamental: this engine was simply never going to be worth the effort. Even the Kasei would have been a better choice, despite it ALSO being somewhat temperamental and likely requiring significant ballast to balance it out again

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## FLYBOYJ (Aug 5, 2022)

Spindash64 said:


> Yeah, in hindsight that was me talking about of my ass. I DO Still argue that, in the case of the Ki-61-II, it was among the little things that added up as red flags to say "This new engine ain't it, chief". If water injection had been developed for the engine, then maybe the available power could have been enough to actually improve the climb rate. But as it stands, even the Ha-40 was a bit temperamental: this engine was simply never going to be worth the effort. Even the Kasei would have been a better choice, despite it ALSO being somewhat temperamental and likely requiring significant ballast to balance it out again


No, it's all good and you probably have valid points about the Ki-61.

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## MiTasol (Aug 5, 2022)

Spindash64 said:


> Yeah, in hindsight that was me talking about of my ass.



Don't beat up on yourself - all the smarter people come here to learn.

to twist the old saying _he who never made a mistake never made learnt anything_

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## Thumpalumpacus (Aug 5, 2022)

Spindash64 said:


> Yeah, in hindsight that was me talking about of my ass.



I'm not gonna lie, I can respect any guy who can write this about himself. I don't have a very informed opinion on this discussion, but I now have a somewhat-informed opinion about what kind of guy you are: one who can admit error.

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## GrauGeist (Aug 5, 2022)

I'm used to being wrong.

I was married - twice...

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## Thumpalumpacus (Aug 5, 2022)

GrauGeist said:


> I'm used to being wrong.
> 
> I was married - twice...



Well, there's at least one mistake there, lol.

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## Admiral Beez (Aug 5, 2022)

Gloster F5/34. Install the intended Perseus or an US radial and change to P-36 like undercarriage.


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## nuuumannn (Aug 6, 2022)

Spindash64 said:


> Depending on when this was implemented, it could arguably be of greater importance than applying armor plate to the Zero, if only because making use of better pilot protection would requires a complete overhaul of the Japanese military's culture and view of the value of a serviceman's life: it doesn't matter if they survive to bail out or ditch, no one will be coming to save them.



Well, there is that point of view, but the other view is that the Japanese did apply better protection to their aircraft, the Allies just did it sooner. At the time of Pearl Harbor, not all the navy's F4Fs had self-sealing tanks. The early models rolled off the production line without them. Later models of A6M did have better protection, including self-sealing tanks. The problem/consideration (depending on which end of the telescope you wanna look down) was the specification to which the A6M was built versus the engines available. Nakajima deemed the specs too difficult and didn't even try, although the Ki-43 was a good fighter with similar performance, if not a naval aircraft. Because it took so long, as you know, to produce the A6M's replacement it was kept in service and upgraded beyond what was expected and beyond its useful life, so adding extra weight was definitely going to stifle its remarkable manoeuvrability while maintaining the performance it had with given engines. 

Not being saved by their own people wasn't necessarily something the Japanese wanted, but it didn't really have the resources to do so, particularly as the war wore on and they began to lose territory - not every Japanese pilot was a Kamikaze, they did expect to survive, after all, why issue them with parachutes if they didn't?

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## MiTasol (Aug 6, 2022)

nuuumannn said:


> Well, there is that point of view, but the other view is that the Japanese did apply better protection to their aircraft, the Allies just did it sooner. At the time of Pearl Harbor, not all the navy's F4Fs had self-sealing tanks. The early models rolled off the production line without them. Later models of A6M did have better protection, including self-sealing tanks. The problem/consideration (depending on which end of the telescope you wanna look down) was the specification to which the A6M was built versus the engines available. Nakajima deemed the specs too difficult and didn't even try, although the Ki-43 was a good fighter with similar performance, if not a naval aircraft. Because it took so long, as you know, to produce the A6M's replacement it was kept in service and upgraded beyond what was expected and beyond its useful life, so adding extra weight was definitely going to stifle its remarkable manoeuvrability while maintaining the performance it had with given engines.
> 
> *Not being saved by their own people wasn't necessarily something the Japanese wanted,* but it didn't really have the resources to do so, particularly as the war wore on and they began to lose territory - not every Japanese pilot was a Kamikaze, they did expect to survive, after all, why issue them with parachutes if they didn't?



I suspect to a certain extent that we are still victims of ww2 propaganda. The A6M had a built in flotation system our aircraft did not but the pilot/crew had a life jacket or life raft

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## EwenS (Aug 6, 2022)

MiTasol said:


> I suspect to a certain extent that we are still victims of ww2 propaganda. The A6M had a built in flotation system our aircraft did not but the pilot/crew had a life jacket or life raft


Flotation bags were more of an inter-war thing for the RN/USN. Possibly an effort to save money back then by rescuing the aircraft. Although early F4Fs seem to have had them.






Warbird Information Exchange • View topic - Aircraft Emergency Flotation Bags ...







www.warbirdinformationexchange.org


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## cherry blossom (Aug 6, 2022)

Coming back to Kawasaki, one possibility is to completely skip even the Ki-61-I and build a Ki-100 analogue from 1942. From late 1941 or early 1942, Mitsubishi were producing the Kinsei 54 for the D3A2 or the H6K5 with 1200 hp at 3000m or 1100 hp at 6200m both at 2500 rpm and with 1300 hp at 2600 rpm available for take off. By 1943, a Ha 112 II of a Ki-46 III gave 1500 hp for take off with 1350 hp at 2000m and 1250 hp at 5800m, all at 2600 rpm.

I don't know when the Ha 112 II (Kinsei 60 series) with an extra bearing and direct fuel injection became available in quantity. Wikipedia says that the Ki-46-III first flew in December 1942. However, it seems that only 10 were produced during 1943 (see Login) and the Ki-46 II was kept in production in parallel throughout 1943. I suspect that this relates to the story that Bosch never provided Japan with the machine tools to make the fuel injection system for the DB 601. The result was that Kawasaki designed its own system for the Ha-40 which was unreliable while Mitsubishi reverse engineered the Bosch system for the Aichi Atsuta. However, I think that I read somewhere that at least initially each Mitsubishi system was essentially hand made rather than mass produced. Mitsubishi thus had the ability to build fairly reliable fuel injection systems for other engines including the Kinsei and Kasei but could not produce them quickly in 1943.


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## SaparotRob (Aug 6, 2022)

GrauGeist said:


> I'm used to being wrong.
> 
> I was married - twice...


A bachelor is a man who didn't make the same mistake once.

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## Spindash64 (Aug 6, 2022)

nuuumannn said:


> Well, there is that point of view, but the other view is that the Japanese did apply better protection to their aircraft, the Allies just did it sooner. At the time of Pearl Harbor, not all the navy's F4Fs had self-sealing tanks. The early models rolled off the production line without them. Later models of A6M did have better protection, including self-sealing tanks. The problem/consideration (depending on which end of the telescope you wanna look down) was the specification to which the A6M was built versus the engines available. Nakajima deemed the specs too difficult and didn't even try, although the Ki-43 was a good fighter with similar performance, if not a naval aircraft. Because it took so long, as you know, to produce the A6M's replacement it was kept in service and upgraded beyond what was expected and beyond its useful life, so adding extra weight was definitely going to stifle its remarkable manoeuvrability while maintaining the performance it had with given engines.
> 
> Not being saved by their own people wasn't necessarily something the Japanese wanted, but it didn't really have the resources to do so, particularly as the war wore on and they began to lose territory - not every Japanese pilot was a Kamikaze, they did expect to survive, after all, why issue them with parachutes if they didn't?


That's certainly correct, but the Japanese were still a bit too slow to recognize the value of a single pilot. The Armor plating and lack of self-sealing fuel tanks weren't the main problem: they were A concern, but as you mentioned, these weren't entirely standard issue at the time of the Zero's debut, and self-sealing fuel tanks compromise internal fuel storage space, limiting range. The larger problem was, again, in doctrine. This is more noticeable with the Japanese army (the infantry specifically), which was downright verbally and emotionally abusive. The Navy, in comparison, was far better at treating its men as human, but they were still prey to the idea that, for a country with high population density and limited resources, it was better to not risk spending all of your resources on them.

On paper, that made sense at the time, but what eventually became clear is that a pilot with combat experience is worth far more than an aircraft, especially pilots like those of the IJN pre Midway. Their mistakes didn't really become apparent in this regard until after Midway, where they doubled down and sent pilots of rapidly degrading quality to the front lines with minimal training in an attempt to take the load off their few surviving pilots. Instead, what they should have done is what the Allies had started doing, which is rotating pilots back home after a certain number of sorties to work as instructors and give "fresh" combat advice to new pilots. I can't fault the Japanese on this entirely, as the Germans made the same mistake. It just became more noticable more quickly with Japan due to Midway decimating much of their naval air experience, meaning they had far less room for error.

That's why I'm arguing that they would have been better served by attempting to fit a better machine gun to the Zeros earlier: the Ho-103 was roughly twice the weight of the Type 97 aircraft machine gun, but fired rounds with more than triple the mass. The RoF while synchronized was unfortunately only around 60-70% that of a synchronized Type 97 (400rpm vs 600-700), but the math still works out so that the Ho-103 will have comparable "power" in terms of kinetic energy of a ball round times rate of fire, to a pair of synchronized 97s. The larger 12.7mm rounds can also carry much greater incendiary, explosive, or armor piercing effect, while the rifle caliber rounds will be much less effective against not only components such as fuel tanks or the engine, but will have even less effect if hitting the wings or rear fuselage.

I'm not phrasing it very well, but I think you understand my point: Rifle caliber machine guns just aren't worth it in 1942.

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## nuuumannn (Aug 6, 2022)

Spindash64 said:


> That's certainly correct, but the Japanese were still a bit too slow to recognize the value of a single pilot. The Armor plating and lack of self-sealing fuel tanks weren't the main problem: they were A concern, but as you mentioned, these weren't entirely standard issue at the time of the Zero's debut, and self-sealing fuel tanks compromise internal fuel storage space, limiting range. The larger problem was, again, in doctrine. This is more noticeable with the Japanese army (the infantry specifically), which was downright verbally and emotionally abusive. The Navy, in comparison, was far better at treating its men as human, but they were still prey to the idea that, for a country with high population density and limited resources, it was better to not risk spending all of your resources on them.



Yup, and these are good points, Spindash, for the reasons you mentioned, and I certainly don't wish to go into the Japanese warrior culture too deeply, but, and this was mentioned by MiTasol in his post, the Zero was engineered with manoeuvrability in mind, so was supposed to be able to get itself out of trouble before the enemy could get a bead on it, but if it did get shot down a modicum of protection for the pilot in case he was over water was provided, the floatation bags. Here's what I mean, see the picture below: To get into the cockpit the pilot presses wee buttons next to these pegs, which pop out from the fuselage, from where they sit flush with the outer skin. This enables the pilot to access the cockpit without standing on the wing and buckling its thin skin. On the inside end of the spring loaded pegs is a mushroom shaped head, which prevents the pegs from puncturing the floatation bag in its inflating state, once it inflates in the water, to enable the pilot to get out. Obviously he's not gonna be worrying too much about the delicate wing outer skin, but those pegs in their retracted state won't puncture the inflating floatation bag, giving the pilot a precious few seconds longer to get out of the sinking aeroplane. That's care and consideration right there.





NX712Z 12

Sure, the Japanese _were_ slow to embody further protective measures into their aircraft compared to the Allies. Their philosophy was akin to that of the battlecruiser, speed (and manoeuvrability in this specific case) over armour plating, to their detriment of course, but let's consider their logic first before we rush to say they didn't care so much for the common pilot. This was their philosophy and until the Allies got wise, it was working for them. When the aircraft that the Japanese designed before Pearl were designed, very few, if any foreign fighters had armour and self-sealing tanks applied from the outset as they were designed. Most aircraft had these things added following combat experience. The Allies learned fast that they were necessary, but aircrews were lost learning those lessons (The US military had British aircrew lose their lives in combat so they could learn from what these things offered, of course  ).

The Japanese took longer, but once the shooting started, that stuff came as standard on new designs. The Ki-44, the Ki-84, the J2M and A7M - the latter two designed by Horikoshi, responsible for the A6M, all had armour plating applied from the outset, and of course the A7M was designed to succeed the A6M in service. As mentioned, the Zero was gonna be hampered by them regardless because of its design philosophy, so the push was not so great because for the first year of the war in the Pacific it was doing pretty good for itself and back in the war offices at home, the A7M was being promised within months, so modification wasn't strictly urgent. Why bother, when reasons mentioned earlier? While the Japanese regard for human life was different to ours, claiming the Japanese didn't care about its pilots doesn't hold water when logical evidence is applied, but I understand your point.




Spindash64 said:


> 'm not phrasing it very well, but I think you understand my point: Rifle caliber machine guns just aren't worth it in 1942.



Nope, you made your point clearly and concisely, so hat's off to you, and I agree with you on this.

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## Admiral Beez (Aug 6, 2022)

nuuumannn said:


> Sure, the Japanese _were_ slow to embody further protective measures into their aircraft compared to the Allies.


I wonder what Japan would have built if they‘d prioritized protection, firepower and speed over agility and endurance. Of course to build what is akin to a Japanese F4F-4, Mitsubishi needs a more powerful engine.


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## PAT303 (Aug 7, 2022)

Admiral Beez said:


> I wonder what Japan would have built if they‘d prioritized protection, firepower and speed over agility and endurance


A MkII Spitfire or Bf109E-4


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## Shortround6 (Aug 7, 2022)

Admiral Beez said:


> Gloster F5/34. Install the intended *Perseus* or an US radial and change to P-36 like undercarriage.



Put the sleeve valve Kool-Aid back on the table.
Back away from the table.
Turn towards the light. 
RUN towards the light. 
Fall to your knees and bask in the light of the poppet valve.

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## MiTasol (Aug 7, 2022)

PAT303 said:


> A MkII Spitfire or Bf109E-4



The MII Spitfire had no protection when designed and when it left the factory. Not even the flotation kit that the A6M had.

And it had one tenth third the range of the A6M

*EDIT note to self - do not post when still half asleep. Drink coffee and turn on brain first. Convert miles to Km and vice versa*

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## Shortround6 (Aug 7, 2022)

MiTasol said:


> And it had* one tenth* the range of the A6M


The A6M could fly 4000 miles!!!!!
Holy Crap!!!!!!!!

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## SaparotRob (Aug 7, 2022)

I knew someone would do a "range check" on that post.

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## PAT303 (Aug 7, 2022)

MiTasol said:


> The MII Spitfire had no protection when designed and when it left the factory. Not even the flotation kit that the A6M had.
> 
> And it had one tenth the range of the A6M


The question asked was what would the Japanese have built if they followed European design philosophy, well my guess would be the same planes the Europeans designed. Are you sure the MkII Spit didn't have protection installed from the factory?.

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## Shortround6 (Aug 7, 2022)

Admiral Beez said:


> I wonder what Japan would have built if they‘d prioritized protection, firepower and speed over agility and endurance. Of course to build what is akin to a Japanese F4F-4, Mitsubishi needs a more powerful engine.


Something like this??





Got two out of 3?

Only so much you were going to do with 1250hp engine.

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## Admiral Beez (Aug 7, 2022)

Shortround6 said:


> Fall to your knees and bask in the light of the poppet valve.


There was nothing inheritently wrong with their Mercury, Neptune and Pegasus engines to suggest to Bristol that the poppet valve should be abandoned. Poppet valves were a stupid distraction at both Bristol and Napier, wasting time, treasure and talent that could have seen superlative, R-2800-like poppet valve engines in early RAF service.


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## GrauGeist (Aug 8, 2022)

Admiral Beez said:


> I wonder what Japan would have built if they‘d prioritized protection, firepower and speed over agility and endurance.


They would have probably ended up with a Nakajima KI-84, Kawasaki N1K1-J or Mitsubishi J2M.

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## XBe02Drvr (Aug 8, 2022)

GrauGeist said:


> They would have probably ended up with a Nakajima KI-84, Kawasaki N1K1-J or Mitsubishi J2M.


...several years earlier than they historically did. How about going up against them in P39s and P40s?


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## Shortround6 (Aug 8, 2022)

GrauGeist said:


> They would have probably ended up with a Nakajima KI-84, Kawasaki N1K1-J or Mitsubishi J2M.


They could prioritize whatever they wanted. 

Without the needed engines they were stuck.

The Ki-44 started with a 1260hp engine at 12,149ft with a single speed supercharger, repeat, single speed.

The two speed engine using the same cylinders didn't show up until the summer of 1942 in prototypes. In the fall of 1942 in pre production and in Nov 1942 in actual production. 
The two speed engine 1440hp at 7,000ft and 1320hp at 17,220ft.

But until you have the improved engine with the 2 speed supercharger you are stuck.
The Navy had planned to improve the engine in the Zero, but Nakajima could never get the water injection to actually give them any real increase in power. Without the increase in power they could either "improve" protection and loose performance, or leave protection less than wanted and keep performance, also less than wanted.

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## XBe02Drvr (Aug 8, 2022)

Were they out of touch with the rest of the world, unable to get exotic materials, experiencing a shortage of engineering talent, or suffering from cultural obstacles? What kept them from achievements other major powers seemed to manage?


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## Shortround6 (Aug 8, 2022)

XBe02Drvr said:


> Were they out of touch with the rest of the world, unable to get exotic materials, experiencing a shortage of engineering talent, or suffering from cultural obstacles? What kept them from achievements other major powers seemed to manage?


It is hard to say, it is probably a combination of a number of things.

The US was fortunate in having a large number of engineers. Many of whom worked in manufacturing and processes. 

It doesn't matter how good your design is if you can't produce it, and not only produce it but produce it in quantity. 

At different points US companies figured out different ways of doing things. See some of the photos here. 





Photos...The Secrets of Casting Those Elegant Pratt and Whitney Radial Heads...


...Pratt and Whitney R1830 Twin Wasp engines for the B-24 Liberator...being Manufactured at Buick's plants... ...and some shots of crankshaft manufacturing for the same engines... ...lots more photos on the source pages... ...source page one...CLICK HERE...



www.practicalmachinist.com





You build forged heads if you can't cast good heads.

Or you design ganged slitting saws controlled by cams that cut all the grooves in pass with each wheel controlled in depth independent of the wheel next to it. 

I think it was Ford that figured out how make parts on a rotary casting table? The molds were spun on the table to get the air pockets out of them as the metal flowed into the mold, but their were eight (?) stations on the table. The system allowed for both high quality and high production.

The US made a number of mistakes in production and production planning in WWII, they just didn't make quite as many as some other countries, 
But the US was always trying to eliminate as much hand fitting/finishing as it could even if it meant machinery that costs hundreds of thousands of dollars. 

The Japanese didn't have that luxury. 
In some cases the Americans weren't using exotic alloys. They were using manufacturing technology to make thinner and closer spaced fins to allow for better cooling of the air cooled cylinders even if the alloy/s were the same. And build thousands of engines in one month in one factory.

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## drgondog (Aug 8, 2022)

Shortround6 said:


> Something like this??
> View attachment 680991
> 
> Got two out of 3?
> ...


Hmm, depends on the atitude you are playing with? The P-51B-5 w/1650-3 at 67" @29K delivered 1275Hp and 440+mph clean.. This is unfair comment to you when the discussion relates to early war designs - which were around 1000-1100 hp at Low FTH -


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## Shortround6 (Aug 8, 2022)

drgondog said:


> Hmm, depends on the atitude you are playing with? The P-51B-5 w/1650-3 at 67" @29K delivered 1275Hp and 440+mph clean.. This is unfair comment to you when the discussion relates to early war designs - which were around 1000-1100 hp at Low FTH -


Got me 

We do tend to look at engines as gross power and not net power. That 1275Hp 1650-3 at 29K may have been making around 1800-1900hp(?) in the cylinders. Overcoming friction, pumps and the hundreds of HP to drive the superchargers. In low gear the engine made the same power in the cylinders but got around 1600hp to to the prop. 

The KI-44's engine was improved over the first one. The supercharger was taking around 120hp more to drive at the higher altitude on the later engine.

If you want higher power with poor fuel you either need a really big engine and/or you need high rpm. And either way is going to increase weight unless you have alloys the guys with the better fuel don't.

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## MiTasol (Aug 8, 2022)

XBe02Drvr said:


> Were they out of touch with the rest of the world, unable to get exotic materials, *experiencing a shortage of engineering talent, or suffering from cultural obstacles? *What kept them from achievements other major powers seemed to manage?



They certainly did not suffer from a shortage of engineering talent as the below A6M items will show. 

As far as cultural obstacles go my belief is that, like the USA, they had military "experts" who would not permit the engineering talent to shine. The things holding back the Japanese aircraft industry in many ways mirror the reasons the Allison never had a two speed or integral second stage blower. A beauracracy that will not bend to the changes in what is happening in the real world. As another US example the P-51 is aircraft that would never have seen the light of day if not for the British purchasing commission.

*Shortround responded * _At different points US companies figured out different ways of doing things._

The Japanese were masters at that. Compare the tailgear of any Brit or US aircraft with the tailgear on the A6M. For example compare the P-40 tailgear (or Spitfire, or Grumman, or F4U or P-47) with the A6M. On the P-40 the fore and aft arm and hockey stick weigh about the same as the complete A6M tail gear. Add to the diagram below two gear doors and the operating linkages which is more weight and complexity and more maintenance and more items to get damaged. All the US and UK aircraft had similar contraptions. Some, like the F4U were absolutely massive, far far more complex and weighed a proverbial ton.





Below is the A6M tail gear. The magnesium casting, the magnesium hockey stick and the wheel become the gear door when retracted.
The oleo and shock strut are a single unit so not only far lighter but also far stronger and there is no need for any linkages etc to adjust and jam and fail. I am sure Shimpachi can provide some diagrams of the gear assembled and in both the extended and retracted positions


















Then compare the arrestor hook on the A6M. Unlike most or all of the pre 1943 US and UK aircraft the A6M arrestor hook swivels from side to side which means it will swing to hook the deck cable rather than slipping off of the aircraft is not in line with the deck. Once the aircraft came to a stop the A6M hook could be released from the cockpit. As far as I know no US or UK aircraft could do that.

Also the A6M spar caps are made from essentially what is now called 7075 alloy. The Japanese had this material long before the US.

Photos taken today

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## yulzari (Aug 10, 2022)

Admiral Beez said:


> There was nothing inheritently wrong with their Mercury, Neptune and Pegasus engines to suggest to Bristol that the poppet valve should be abandoned. Poppet valves were a stupid distraction at both Bristol and Napier, wasting time, treasure and talent that could have seen superlative, R-2800-like poppet valve engines in early RAF service.


At the time Bristol decided to go to sleeve valves in lieu of poppet valves it made complete sense. Poppet valves were being limited by low knock levels and valve seat erosion. However, very shortly thereafter developments in fuels and materials allowed poppet valves to deal with higher compression ratios and boost which took away the undoubted previous advantage of the sleeve valve. What Bristol did not do was drop the sleeve valve and revert to poppet valves. Whether this was personal or company face savings or the inertia of having got so far with sleeve valves already I cannot comment buy the original decision to go sleeve valve was justified when it was made. The classic AH Bristol engine is the frequently touted double Pegasus.

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## Shortround6 (Aug 10, 2022)

yulzari said:


> developments in fuels and materials allowed poppet valves to deal with higher compression ratios and boost which took away


That is a general progression and it takes number of paragraphs (if not pages) to even do a decent over view.
It took Almost 15 years to get the Sleeve valve up to the standards of 1939.
There were a few zigs and zags. 
Yes the Sleeve valve was supposed to solve a lot of problems as you said. 
And yes, some of the problems went away in the late 20s or early 30s.

The Sodium cooled exhaust valve was a big equalizer. 
SO were better valve springs, valve spring failure/breakage was a very real problem in the 1920s but by the early 30s engines were running hundreds of hours without such a failure.
Better fuel helped a bit but was actually not that big a deal until the late 30s. 87 octane fuel was only going to work with 3-5lbs of boost in air-cooled engines. 
And with 3-5lbs of boost and higher RPM than the older engines cooling was becoming a real problem with both types of valves. It was a constant battle to get enough cylinder fin area to keep the engine cool enough.

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## Admiral Beez (Aug 10, 2022)

Shortround6 said:


> Yes the Sleeve valve was supposed to solve a lot of problems as you said.
> And yes, some of the problems went away in the late 20s or early 30s.


At which point, Bristol should have seized on the sodium valve stems and better springs and canceled their sleeve valve projects. Maybe the Perseus gets to run in 1932, as a proof of concept. But by then the engineering and materials improvements available should have canceled any need to proceed to the Aquila, Taurus, Hercules and Centaurus. 

However we get there, this, the early abandonment of sleeve valves was one of Britain’s best opportunities for better results.


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## nuuumannn (Aug 10, 2022)

Admiral Beez said:


> I wonder what Japan would have built if they‘d prioritized protection, firepower and speed over agility and endurance.



They did, just not at the same time as the Allies. As I mentioned, the generation of fighters that entered service, or were to enter service after Pearl did so and steered away from older, more traditional means of flighting. Japan wasn't alone in this, Italy was the same, as was the RAF. Th crucible of actual combat changes things in unexpected ways. Before the Spitfire and Hurricane entered service, the Gloster Gauntlet was the RAF's principal fighter. The Spitfire and Hurricane were plenty manoeuvrable and in a slow speed dogfight both could easily defeat a Bf 109 - this was amply demonstrated during the BoB.

Japan didn't have that widespread combat experience at that time to work from - in fact, neither did the USA, so that concept really only came about from the Battle of Britain that such things were vital - no internet for armchair historians to tell the Japanese what they think. We like to think we were superior than Japan because of this, but the lessons _were_ learned, just later simply because the air forces they initially experienced in their Pacific expansion were far less capable or sizable than their own. When you're winning at the time, you don't think about what to do to prevent losing as much as you do to continuing winning. Japan did learn that lesson. It just took time. Yes, though, engine development was less extensive as Allied/German work so did hamper them, but it suited their philosophy.

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## Thumpalumpacus (Aug 10, 2022)

nuuumannn said:


> The Spitfire and Hurricane were plenty manoeuvrable and in a slow speed dogfight both could easily defeat a Bf 109 - this was amply demonstrated during the BoB.
> 
> Japan didn't have that widespread combat experience at that time to work from - in fact, neither did the USA, so that concept really only came about from the Battle of Britain that such things were vital - no internet for armchair historians to tell the Japanese what they think.



I think the Japanese had some experience in slow-speed dogfights over China well before they entered WWII. The Chinese weren't flying any hustlers, mostly I-15s, some I-16s, the occasional Hawk. The IJN naval air corps built a good body of experience there, so far as my reading has shown. I don't know much about their army air ops, but one reason why everyone regards their naval aviators in 1941 as being premier was from this experience dating from 1937-38 and onward. They knew how to dogfight slow, and had the equipment that could do that very well indeed.

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## nuuumannn (Aug 10, 2022)

Thumpalumpacus said:


> I think the Japanese had some experience in slow-speed dogfights over China well before they entered WWII. The Chinese weren't flying any hustlers, mostly I-15s, some I-16s, the occasional Hawk. The IJN naval air corps built a good body of experience there, so far as my reading has shown. I don't know much about their army air ops, but one reason why everyone regards their naval aviators in 1941 as being premier was from this experience dating from 1937-38 and onward. They knew how to dogfight slow, and had the equipment that could do that very well indeed.



I should have been more specific, I meant the kind of experience against fighters of the type that Europe and the US were building at that time. Even during the Spanish Civil War, the lessons learned from the deployment of the Bf 109 took time to learn, in fact, many of the lessons from that conflict were ignored by Britain, the US etc. If anything, the Japanese experience from those conflicts you mention leaned further toward their accepted tactics and assured them they were on the right track. As mentioned, it wasn't until the BoB that the kind of fighter-versus-fighter combat that we acknowledge as being de rigeur emerged.

Japan certainly didn't have that experience and like I said, for the first year of the Pacific War the A6M and Ki-43 and their superior manoeuvrability and tactics reigned supreme. The US Navy's pilots couldn't defeat them one-on-one, so they outsmarted them, because they themselves were learning on the hoof, too. Thankfully, US manufacturers and the USN and USAAC heeded the lessons from the British and Germans scrapping it out over Britain and armour and self sealing tanks were being fitted at the time Japan attacked Pearl.

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## Thumpalumpacus (Aug 10, 2022)

nuuumannn said:


> I should have been more specific, I meant the kind of experience against fighters of the type that Europe and the US were building at that time. Even during the Spanish Civil War, the lessons learned from the deployment of the Bf 109 took time to learn, in fact, many of the lessons from that conflict were ignored by Britain, the US etc. If anything, the Japanese experience from those conflicts you mention leaned further toward their accepted tactics and assured them they were on the right track. As mentioned, it wasn't until the BoB that the kind of fighter-versus-fighter combat that we acknowledge as being de rigeur emerged.
> 
> Japan certainly didn't have that experience and like I said, for the first year of the Pacific War the A6M and Ki-43 and their superior manoeuvrability and tactics reigned supreme. The US Navy's pilots couldn't defeat them one-on-one, so they outsmarted them, because they themselves were learning on the hoof, too. Thankfully, US manufacturers and the USN and USAAC heeded the lessons from the British and Germans scrapping it out over Britain and armour and self sealing tanks were being fitted at the time Japan attacked Pearl.



You're right (if I'm reading you true) that the Japanese certainly held onto WWI concepts of fighter combat -- i.e. dogfighting -- while the world moved on to higher-speed, heavier platforms, outfitted with better protection, working more with velocity in the vertical rather than tying 'em up.

But I don't agree that they were inexperienced with slow-speed dogfights. That was much of their combat regime in China. That was where they were blooded.


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## nuuumannn (Aug 10, 2022)

Thumpalumpacus said:


> But I don't agree that they were inexperienced with slow-speed dogfights.



I think you might have missed what I said, Thump. I didn't say they were inexperienced in dogfight type combat, in fact I said the exact opposite in that the experience they had tended to reinforce what they believed was the right way to fly and flight. I meant that they had not yet learned the lessons of combat that were being learned during the BoB in the summer of 1940, so their experience in that kind of combat was limited.

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## Thumpalumpacus (Aug 10, 2022)

nuuumannn said:


> I think you might have missed what I said, Thump. I didn't say they were inexperienced in dogfight type combat, in fact I said the exact opposite in that the experience they had tended to reinforce what they believed was the right way to fly and flight. I meant that they had not yet learned the lessons of combat that were being learned during the BoB in the summer of 1940, so their experience in that kind of combat was limited.



Allow me to pause and reread then, and forgive me if I'm misunderstanding.

ETA: I've reread, and you're right; I've misunderstood your point. I'm sorry for that.

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## GrauGeist (Aug 10, 2022)

The Chinese Air Force actually had quite a wide range of types at the start of their war with Japan, like the Fiat CR.32, Gloster Gladiator, Boeing P-26, Curtiss Hawk II and Hawk III and even the Dewoitine D.510.

So while these types (and others) were not fast, they were very maneuverable.

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## Greg Boeser (Aug 10, 2022)

I think you misread the IJN pilot's experience in China. The A5M was definitely a dogfighter, but the Zero was an energy fighter, faster and more powerful than anything the Chinese had.
USN pilots noted the Zero pilots' preferred method of attack during Coral Sea and Midway was a diving attack from the rear followed by a steep climb after recovering out front. Because the F4F was only marginally slower, and rolled better, the USN pilots were able to counter these moves.

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## GrauGeist (Aug 10, 2022)

Agreed about the A5M - until it's arrival in China, the Chinese Air Force was able to meet the Japanese in close to equal terms.

The A5M changed all that.

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## XBe02Drvr (Aug 11, 2022)

It seems the lessons you learn fighting a less potent enemy will require a quick recalibration when you finally meet your match. How quickly and efficiently you can accomplish that will determine your prospects in the long slog of an attrition war.

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## nuuumannn (Aug 11, 2022)

Thumpalumpacus said:


> ETA: I've reread, and you're right; I've misunderstood your point. I'm sorry for that.



It's quite alright, dude. No need to apologise.  I misread stuff all the time!

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## nuuumannn (Aug 11, 2022)

XBe02Drvr said:


> t seems the lessons you learn fighting a less potent enemy will require a quick recalibration when you finally meet your match. How quickly and efficiently you can accomplish that will determine your prospects in the long slog of an attrition war.



Totally agree, especially in Japan's case. They did misinterpret a lot and completely underestimate how the United States would react, to their detriment.

What strikes me as interesting about this whole debate regarding the Japanese philosophy of manoeuvrability and little self protection for their aeroplanes is that we, the observers so many years later apply what we know and can only know in hindsight to argue that the Japanese were somehow stupid for doing so. The reality was that _everyone_ was doing what the Japanese were doing, even the Americans. The P-36 was a decent dogfighter (that doesn't get nearly enough attention - I might be biased, I think it's cooler even than the P-40) and could out-manoeuvre the Spitfire and Hurricane, which in themselves were good dogfighters, which proves that manoeuvrability was definitely a virtue in fighters of the late 1930s vintage.

The Japanese took it to extremes in the A6M, of course, but we are so ingrained with that aircraft's history that we believe that it was the be-all and end-all of Japanese design philosophy, but it wasn't. No other fighter the Japanese built was just like the Zero - except other Zeroes of course. Even Horikoshi's subsequent designs eschewed the Zero's advantages for those things we think the Japanese ignored. Yes, the philosophy of the Ki-43 was the same as the A6M, but it wasn't achieved at the same expenses as the A6M. Its design was based on limited engine power, like the Zero, but we simply don't acknowledge that changes in fighter philosophy, like heavy armament, boom and zoom manoeuvres, armour plate and self-sealing tanks came as a _result _of experience with enemy aircraft, not strictly beforehand.

Combat in Europe, as I mentioned earlier illustrated the need for self-sealing tanks, armour plating and heavier armament, but as mentioned, these took time to implement. There were still Bf 109s in frontline service with only four machine gun-calibre weapons in the spring/summer of 1940. The RAF had frontline fighters with eight guns, more than anyone else's fighters at the time, but they still weren't heavy hitting enough and first contact with the enemy in late 1939 proved that the pilots still had to empty their magazines just to bring down a single Heinkel. Spitfires and Hurricanes didn't get heavy cannon as standard until after the Germans. The A6M had cannon as standard, ironically.

So, to conclude, what we were doing was little different to what the Japanese were doing. They took it quite far with the A6M, but it was not the norm. We like to think that these advantages our fighters had were a given because we've come to accept that, but in the first year to two years of WW2, they simply weren't.

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## SaparotRob (Aug 11, 2022)

XBe02Drvr said:


> It seems the lessons you learn fighting a less potent enemy will require a quick recalibration when you finally meet your match. How quickly and efficiently you can accomplish that will determine your prospects in the long slog of an attrition war.


Which is why I think the Ukrainians are training us. The recent conflicts the US has been involved in haven't been against a large army.


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## Thumpalumpacus (Aug 11, 2022)

XBe02Drvr said:


> It seems the lessons you learn fighting a less potent enemy will require a quick recalibration when you finally meet your match. How quickly and efficiently you can accomplish that will determine your prospects in the long slog of an attrition war.



That whole "fighting the last war" thing is not very new.


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## GrauGeist (Aug 11, 2022)

nuuumannn said:


> The P-36 was a decent dogfighter (that doesn't get nearly enough attention


People tend to forget that the P-36 debuted at the same time as the Bf109 and Hurricane and was one of the Premier fighters of the day.

It's performance at Pearl Harbor is often overlooked by the P-40s, but it was first to draw blood in the U.S. involvement and many pilots (my Uncle Jimmy included) would have preferred to have taken it into battle over other American types early in the war.

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## nuuumannn (Aug 11, 2022)

GrauGeist said:


> People tend to forget that the P-36 debuted at the same time as the Bf109 and Hurricane and was one of the Premier fighters of the day.



Great machine!





Hawk 75 static

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## GrauGeist (Aug 11, 2022)

nuuumannn said:


> Great machine!
> 
> View attachment 681428
> Hawk 75 static


My Uncle Jimmy would have gotten into the fray on 7 December if his P-36 had ammunition.

Would be interesting to see how things would have turned out if he (and his mates) had been able to arm their P-36s as the attack waves were heading home.

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## Admiral Beez (Aug 11, 2022)

Let's improve these RAF Lend Lease failures....

Vultee Vanguard






Vought Chesapeake






Brewster Bermuda






Fine aircraft, but what can we amend for the Dauntless and Helldiver to meet RN/FAA needs? A folding wing might suffice on the former.











I've intentionally left out the Brewster Buffalo as for many it's a obvious candidate. Though if available in sufficient numbers (4 squadrons cannot defend a land mass about the size of the UK) and properly used it could have done well in Malaya, IMO.

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## SaparotRob (Aug 11, 2022)

I thought the SBD had a shorter wingspan to avoid the necessity of folding wings.


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## Admiral Beez (Aug 11, 2022)

SaparotRob said:


> I thought the SBD had a shorter wingspan to avoid the necessity of folding wings.


Yes, but for the RN to consider it, it must be even shorter. Though HMS Indomitable (forward lift only) and Furious should be feasible.

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## GrauGeist (Aug 11, 2022)

SaparotRob said:


> I thought the SBD had a shorter wingspan to avoid the necessity of folding wings.


The design was kept relatively compact (41 foot wingspan) and the wings were designed for strength, so folding was not an option because of that.

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## Admiral Beez (Aug 11, 2022)

GrauGeist said:


> The design was kept relatively compact (41 foot wingspan) and the wings were designed for strength, so folding was not an option because of that.


Given its success and robustness I can't fault its designers. It is noteworthy that Dauntless and Aichi D3A aside (granted, the two most important and successful naval DBs of the war) the other naval dive bombers, including the Skua, Loire-Nieuport LN.401, Vought SB2U, Curtiss SB2C, Stuka (prototype), Yokosuka D4Y and Aichi B7A had folding wings.

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## Shortround6 (Aug 11, 2022)

Admiral Beez said:


> Let's improve these RAF Lend Lease failures....
> 
> Vultee Vanguard


Why???

The Vanguard was an attempt to get more sales from trainer airframe (lower cost of tooling).
It broke a lot in service. 

You can fix anything with enough time and money. 
Question is if the time and money is better spent elsewhere. 

The RAF never ordered it. 
It was offered to them for free when they could not deliver the planes to Sweden. 
The RAF took them to use as trainers (they didn't want them for combat even in the months after the BoB)

There is more to the story but unless you change quite a bit you are putting lipstick on a pig. 



Admiral Beez said:


> Vought Chesapeake


Again, why?
It was underpowered. Unless you can fix the power problem it doesn't matter what else you do with it.
Yes Vought had built a prototype with a P&W R-1830 engine. There were no takers.
The Chesapeake, as built was not used to dive at over 60 degrees. 

You want a better dive bomber than the Skua?

Put a better engine on the Skua, increase gross weight

BUILD BETTER BOMBS!!!

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## XBe02Drvr (Aug 11, 2022)

GrauGeist said:


> The design was kept relatively compact (41 foot wingspan) and the wings were designed for strength, so folding was not an option because of that.


A folding wing SBD would have required a Grumman style fold for height reasons, as well as a thicker (for strength) airfoil, making it an overweight, slow, TBD clone. Ed Heineman found the sweet spot to put it all together. Don't butcher success.

And the Helldiver? Scuttle it and the Curtiss it rode in on, and put Ed to work on the Skyraider early. Meanwhile, up-engine the SBD with the higher powered version of the R1820. I think they eventually got up to ~1475 HP.

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## Shortround6 (Aug 11, 2022)

XBe02Drvr said:


> Meanwhile, up-engine the SBD with the higher powered version of the R1820. I think they eventually got up to ~1475 HP.


They did but not in WW II unless the last few months?

The SBD went through 3 major engine changes (not counting a carburetor or magneto change) and they were _major_ changes.

The SBD-1/4 used a 1000hp engine. 
The SBD-5 used a 1200hp engine. 
The SBD-6 used a 1300-1350hp engine.

The engine used in the SBD-5 was similar to the engine used in the F2A-3 and in the later Mohawks and the basic engine used in the B-17 and other aircraft. 
The engine used in the SBD-1/4 was an R-1829-52 and used a different crankcase, different crankshaft, different cylinder barrels and different cylinder heads. in other words it was built on older tooling. 
The engines used in the SBD-6 was another major change with once again, different everything and the 1300hp and 1350 hp versions used a different crankshaft although I don't know if you could swap the new crankshaft into the existing engine. 

The 1425hp versions weren't shipped until 10/45.

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## EwenS (Aug 11, 2022)

The Vought Chesapeake was an inheritance from a French contract taken over immediately prior to the French surrender in June 1940. Having got 50 of them in early 1941 the question was what to do with them. 811 squadron FAA formed on them in July 1941 and was intended to go aboard one of the escort carriers then building in the USA. They quickly found that its take off run would be too long for those ships so the squadron swapped to Swordfish in Nov 1941. Eric Brown wrote that some of its problems stemmed from British efforts “to render it a ‘fully operational’ aeroplane”.


Britain never intended to acquire the SBD as a front line aircraft so the question of needing to modify it for use from British carriers never arose. It only acquired 9 SBD-5 in late 1943 / early 1944 for trials purposes. Deliveries were divided between the RN and RAF. RN interest was in the bomb sight it was fitted with, as that was also to be fitted to the Curtiss SBW Helldivers that it was about to receive. The RAF was interested in comparative trials against the Vultee Vengeance.

Britain did order 450 SBW Helldivers from the Canadian Car & Foundry production line. But such were the delays in the Helldiver programme it only ever received 26 late 1943 / early 1944. Only one squadron was formed on them. Its history is here:-


1820 Naval Air Squadron



Perhaps the best way of putting its problems is to quote Eric Brown who test flew it in Oct 1944:-
_“...the handling characteristics of the ‘Beast’ were such that it would never have been allowed near a British carrier deck!”_

He concluded:-
_“....Quite frankly, with the terrible aileron control at approach speed and the excessive longitudinal trim change with engine power, the Helldiver would _never _have been acceptable for deck landing by British standards, and, indeed was never flown onto a British carrier by an FAA pilot.”_

That last statement isn’t entirely true as a detachment from 1820 squadron spent 2 days aboard the escort carrier Speaker for deck landing training at the end of Oct 1944 before returning to a shore base and disbanding in mid-Dec 1944.

The other problem with it is one of physical size when folded. Folded width 22’6”, folded height 16’10”. So they don’t fit either an Illustrious or Implacable class carrier as they are too tall. Even if you chop a bit off the wings like the Corsair (which would have probably made the handling around the deck worse) you are only going to be able to fit them two abreast in the hangar, compared to three abreast for the Barracuda and Avenger.

By the time that the Helldiver was rolling of Canadian production lines in July/Aug 1943, the RN had a dive bomber in service with increasing numbers coming off 3 British production lines. While the Fairey Barracuda May not have been the best dive and/ or torpedo bomber of WW2, it handled very well around the flight deck and in particular being easy to land. 

So really the Helldiver had nothing to commend it to the RN.

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## GrauGeist (Aug 11, 2022)

Admiral Beez said:


> Given its success and robustness I can't fault its designers. It is noteworthy that Dauntless and Aichi D3A aside (granted, the two most important and successful naval DBs of the war) the other naval dive bombers, including the Skua, Loire-Nieuport LN.401, Vought SB2U, Curtiss SB2C, Stuka (prototype), Yokosuka D4Y and Aichi B7A had folding wings.


The one attribute the SBD had over the others listed, was it's ability to enter a near 80° dive with absolute rock-solid stability, which in turn, enhanced it's accuracy.

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## Shortround6 (Aug 11, 2022)

EwenS said:


> Eric Brown wrote that some of its problems stemmed from British efforts “to render it a ‘fully operational’ aeroplane”.



Since they never changed the engine from the 825hp R-1535 engine and they did try to add machine guns and protected tanks(?) and crew protection (?) we can see where this was going to go. 

I would note that while max fuel may have been 310 gallons (unprotected tanks) that would have been with no bomb. 

If anybody has not downloaded this manual yet 






upload pilots handbook for sbd-3 dauntless


Hi All, uploaded pilots handbook for sbd-3 dauntless cheers Jerry



ww2aircraft.net





For the SBD I would strongly advise it as it has weights and capacities for both protected and unprotected versions and performance charts/tables. 
It is also at an early gross weight and would be more comparable to other early war aircraft. 

I would also note that Vought's original idea was to use a fully feathering or reversible pitch propeller as an air brake for diving. 
This did not work out in practice and most (all?) of the SB2Us tried to use lowering the landing gear as a substitute. 

Going back to the SBD-3, the dive brakes could be extended at any speed less that the max level speed of the airplane. 
However the landing flaps were not to lowered at speeds over 140kts. Neither was the landing gear supposed to lowered at speeds over 140kts. 

Not saying that the SB2U couldn't lower it's landing gear at higher speeds. Just saying that if you are going to change things sometimes more stuff needs to be changed that it first appears.


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## MiTasol (Aug 11, 2022)

XBe02Drvr said:


> *A folding wing SBD would have required a Grumman style fold for height reasons,* as well as a thicker (for strength) airfoil, making it an overweight, slow, TBD clone. Ed Heineman found the sweet spot to put it all together. Don't butcher success.
> 
> And the Helldiver? Scuttle it and the Curtiss it rode in on, and put Ed to work on the Skyraider early. Meanwhile, up-engine the SBD with the higher powered version of the R1820. I think they eventually got up to ~1475 HP.



Or they could just fold the tips like on the A6M - and have the absolute minimum weight penalty to go with it


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## ThomasP (Aug 11, 2022)

The French model of the SB2U (the V-156-F) had wing fence dive brakes in service, and did not lower the landing gear when diving. From what I have read the French considered the V-156-F quite effective.

The R-1830 powered version was intended for sale to the French.

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## XBe02Drvr (Aug 12, 2022)

MiTasol said:


> Or they could just fold the tips like on the A6M - and have the absolute minimum weight penalty to go with it


Would that reduce span enough to make the SBD viable for the RN?


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## wuzak (Aug 12, 2022)

Some developments that could have helped the Spitfire was to get multiple position flaps and radiator outlets, each of which was only 2 positions on the Spitfire.

Multiple position flaps may have allowed shorter take-offs by enabling partial flaps to be selected. As it was they were either up or down. It also would have helped Seafires.

Multiple position output flaps for the radiators could have improved radiator efficiency by getting the correct amount of cooling, instead of too much or too little.

Smith also, apparently, admitted that that the areas for the inlet and outlet of the radiator duct were incorrectly sized. IIRC, he thought the inlet was too large.


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## EwenS (Aug 12, 2022)

XBe02Drvr said:


> Would that reduce span enough to make the SBD viable for the RN?


The complication with the SBD is that the ailerons extend to the wingtips and would have to be split. Presumably they can’t be reduced in size.

Illustrious class lift size was 45x22ft. The forward lift only in Indomitable and the Implacables increased to 45x33ft.


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## XBe02Drvr (Aug 12, 2022)

EwenS said:


> The complication with the SBD is that the ailerons extend to the wingtips and would have to be split. Presumably they can’t be reduced in size.


That's why the wing fold would have to be at the center section/wing panel junction, making a conventional fold too tall and a Grumman-style fold necessary. A Grumman fold is troublesome on a wing as thin as the SBD's for strength reasons, probably requiring a redesigned thicker (and draggier) wing.


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## ThomasP (Aug 12, 2022)

SBD wing airfoil was the NACA 2415 root to 2409 tip, with a chord of 115" at the join of the inner/outer wing sections. The F4F/F6F/TBF were all NACA 23015 root to 23009 tip. SBD has same T/C ratio as the airframes with the Grumman STO wing fold - so should be enough room in terms of wing thickness.

From SBD-2 Erection & Maintenance manual:

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## EwenS (Aug 12, 2022)

XBe02Drvr said:


> That's why the wing fold would have to be at the center section/wing panel junction, making a conventional fold too tall and a Grumman-style fold necessary. A Grumman fold is troublesome on a wing as thin as the SBD's for strength reasons, probably requiring a redesigned thicker (and draggier) wing.


And then you run into the height constraints on British carriers. Not the 17’6” height of the then modern US ships (earlier ones had more) but 16’ on pre-war and Illustrious class and 14’ in the upper hangar of Indomitable and both hangars in the Implacables.


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## MiTasol (Aug 12, 2022)

XBe02Drvr said:


> Would that reduce span enough to make the SBD viable for the RN?


Depends on where they made the fold. Certainly worked on the Spitfire though the aileron issue may have been a killer.


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## GrauGeist (Aug 12, 2022)

I imagine that if they redesigned the SBD's wing to fold (in any configuration), it would affect it's dive angle for the reason that once those massive dive brakes deploy, that would put considerable stress on the joints.

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## Reluctant Poster (Aug 13, 2022)

nuuumannn said:


> Totally agree, especially in Japan's case. They did misinterpret a lot and completely underestimate how the United States would react, to their detriment.
> 
> What strikes me as interesting about this whole debate regarding the Japanese philosophy of manoeuvrability and little self protection for their aeroplanes is that we, the observers so many years later apply what we know and can only know in hindsight to argue that the Japanese were somehow stupid for doing so. The reality was that _everyone_ was doing what the Japanese were doing, even the Americans. The P-36 was a decent dogfighter (that doesn't get nearly enough attention - I might be biased, I think it's cooler even than the P-40) and could out-manoeuvre the Spitfire and Hurricane, which in themselves were good dogfighters, which proves that manoeuvrability was definitely a virtue in fighters of the late 1930s vintage.
> 
> ...


The primary requirement that dictated no self-sealing fuel tanks was to achieve the fantastic range that no fighter aircraft of the era could remotely duplicate. The Japanese Navy was the only air force in the world that realized the need for long range escort of bomber and actually solved the problem.

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## drgondog (Aug 13, 2022)

Reluctant Poster said:


> The primary requirement that dictated no self-sealing fuel tanks was to achieve the fantastic range that no fighter aircraft of the era could remotely duplicate. The Japanese Navy was the only air force in the world that realized the need for long range escort of bomber and actually solved the problem.


Actually, AAC/AAF recognized the Need, just failed to elicit proper RFP out of Materiel Command before WWII engulfed US. Arnold was well aware that day fighters dominated bombers in Spanish Civil War and BoB. Others in chain of command, particularly Spaatz were of the opinon that high altitude performance of B-17 would reduce attrition sufficiently to achieve strategic objectives as we began deployment of 8th AF to UK.

Additional Factors seperating IJN from AAC was bombing doctrine and platforms. There was no need for Japan to produce long range escort fighters with high altitude performance 

The A6M would not have been a great escort for 8th AF in ETO.

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## GrauGeist (Aug 13, 2022)

The A6M (and KI-43) had long range because of the distances involved in patrolling and expanding the Empire.

That they could escort their bombers over long distances was a bonus to their primary mission.

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## Reluctant Poster (Aug 13, 2022)

drgondog said:


> Actually, AAC/AAF recognized the Need, just failed to elicit proper RFP out of Materiel Command before WWII engulfed US. Arnold was well aware that day fighters dominated bombers in Spanish Civil War and BoB. Others in chain of command, particularly Spaatz were of the opinon that high altitude performance of B-17 would reduce attrition sufficiently to achieve strategic objectives as we began deployment of 8th AF to UK.
> 
> Additional Factors seperating IJN from AAC was bombing doctrine and platforms. There was no need for Japan to produce long range escort fighters with high altitude performance
> 
> The A6M would not have been a great escort for 8th AF in ETO.


Thats why I added the statement "and actually solved the problem". Certainly long range escort at high altitude was a much more difficult problem given the limitations of the engines available in 1940

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## ThomasP (Aug 13, 2022)

Part of the A6M specification required the ability to escort bombers over long ranges. The A5M4 (effective ROA of ~300 miles with DT) was found deficient for escorting bombers over the ranges required during many of the missions occurring in the late-1930s operations.

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## cherry blossom (Aug 14, 2022)

Coming back to Japanese engines, it is clear that Japan had very good engineers. However, they only had so many good engineers and they spread them too thinly. Japan had more engines types in production than most other countries. It is rather easy for us to tell them which designs to push and which ones to abandon but it was harder at the time. It also needed the Army and the Navy to agree on what to tell Mitsubishi and Nakajima to do. 

Mitsubishi had three sizes of cylinder with two of the sizes offered in 14 and 18 cylinder versions. They also made experimental 22 cylinder and 28 cylinder radials and 24 cylinder liquid cooled H. 

Nakajima also had three sizes of cylinder and made 14 and 18 cylinder radials using each cylinder (also the 9 cylinder Kotobuki and Hikari although these were probably not developed in WW2). Again there was interest in a 24 cylinder H and a 22 cylinder radial.

Going from development to production, Mitsubishi mass produced four radials during WW2, the 28l Zuisei, the 32l Kinsei, the 42l Kasei and the 54l Ha-104 (and tried to produce the MK9). Nakajima mass produced the 28l Sakae, the 36l Homare, the 37.5l Ha-5/Ha-41/Ha-109 and the 45l Mamoru (also the Kotobuki remained in production until 1943). For comparison, Pratt & Whitney produced the R-1830, the R-2000 and the R-2800 whilst Wright produced the R-1820, the R-2600 and the R-3350. BMW produced the BMW-132, the Bramo-323, the BMW-801 and the BMW-003. Daimler Benz produced the DB-601, 605 and 603 as well as the coupled DB-606 and 610. Rolls Royce produced the Peregrine, the Merlin, the Griffon and the Vulture as well as the Welland jet.

Thus there is a case that both Mitsubishi and Nakajima designed and produced more engines types than other comparable companies. Obviously simply listing the names does not prove the case. We could argue that Rolls Royce may have abandoned the Peregrine and the Vulture to focus on the Merlin and the Griffon but that the Merlin was extensively redesigned to give the Merlin 60 and Merlin 100 series. However, adding fuel injection and water injection to give the Kinsei 60 series and the Kasei 20 series was also a big step. Unfortunately for Japan it was quite a slow step as these were used in prototypes flying in December 1942, the Ki-46-III and the G4M2, but in both cases production built up slowly with Ki-46-IIs and G4M1s being produced throughout 1943. Also note that the Kasei was produced with contra-rotating propellers for the N1K1 and with a long extension shaft for the J2M.

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## MiTasol (Aug 14, 2022)

cherry blossom said:


> Coming back to Japanese engines, it is clear that Japan had very good engineers. However, they only had so many good engineers and they spread them too thinly. Japan had more engines types in production than most other countries. It is rather easy for us to tell them which designs to push and which ones to abandon but it was harder at the time. It also needed the Army and the Navy to agree on what to tell Mitsubishi and Nakajima to do.
> 
> Mitsubishi had three sizes of cylinder with two of the sizes offered in 14 and 18 cylinder versions. They also made experimental 22 cylinder and 28 cylinder radials and 24 cylinder liquid cooled H.
> 
> ...


Pretty good summary however Pratt also produced the R-985 throughout the war and likewise Wright produced their R-975. Pratt was also still producing the R-1690 and R-2180 Hornet engines at the start of the war.

Like the Japanese Pratt, Rolls and Wright all dabbled in other engines (eg the Wright R-1300 started life in 42) and all did major redesigns of their main products. Unlike the Japanese they did however have Army and Navy, and RAF, who who cooperated with each other and who would not fund too many competing projects.

The 1938 R-1820 F52 series engines at 890hp were much heavier and drank far more fuel than the Sakae which was probably in pre-production testing at that time. The 1820 and 30 were engines that had been around for years by the beginning of ww2 whereas Mitsubishi and Nakajima only created their designs in the very late 30's. To give you a rough idea of where public knowledge of Japanese engine design and production stood in 1938 see Janes below.

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## BobB (Aug 14, 2022)

MiTasol said:


> Pretty good summary however Pratt also produced the R-985 throughout the war and likewise Wright produced their R-975. Pratt was also still producing the R-1690 and R-2180 Hornet engines at the start of the war.
> 
> Like the Japanese Pratt, Rolls and Wright all dabbled in other engines (eg the Wright R-1300 started life in 42) and all did major redesigns of their main products. Unlike the Japanese they did however have Army and Navy, and RAF, who who cooperated with each other and who would not fund too many competing projects.
> 
> ...


P&W quit building single row engines after the US entered the war. Continental, Jacobs and I don't remember who else built R-985 & R-1340 The last US built R-985 were by Jacobs at a government owned plant near Pottstown, PA. P&W production of R-1830 peaked in 1943, then started dropping as Buick & Chevrolet R-1830 production hit their peak rate. Wright production of R-760/R-975(I don't have numbers for R-975 alone) peaked in 1942, then started dropping down to only 20 engines in December 1943. Continental took over R-975 production and continued building them into the 1950's. It made sense for P&W and Wright to get out of building engines that were not being further developed.

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## SaparotRob (Aug 14, 2022)

Are any of these engines still being made? They must be getting scarce.


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## XBe02Drvr (Aug 15, 2022)

SaparotRob said:


> Are any of these engines still being made? They must be getting scarce.


They're nearly indefinitely rebuildable and reworkable if anybody's willing to pay for it.

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## ThomasP (Aug 15, 2022)

The last new-build R-1820 was produced in 1964. I think the R-1820 can claim the last new production of the engine types listed above?

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## yulzari (Aug 15, 2022)

GrauGeist said:


> I imagine that if they redesigned the SBD's wing to fold (in any configuration), it would affect it's dive angle for the reason that once those massive dive brakes deploy, that would put considerable stress on the joints.


The issue with joints for folding is weight not strength. well designed folding joints are as strong as non folding wings but heavier to achieve this. After all, all wings are a conglomeration of joints arranged so as to keep the wings in the shape intended by the designer, folding wings merely have a few big ones that can swivel or be locked in place.

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## MiTasol (Aug 15, 2022)

And a small fold at the tip like the A6M and Seafire weighs very little - plus is not affected by any of the stress that comes from deploying dive flaps.


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## XBe02Drvr (Aug 15, 2022)

ThomasP said:


> The last new-build R-1820 was produced in 1964. I think the R-1820 can claim the last new production of the engine types listed above?


Still in use on T28s, S2s, C1s, and C117s when I got out of the Navy in 1974. Clatterboxes, they always sounded like they were about to come apart at the seams.

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## BobB (Aug 15, 2022)

ThomasP said:


> The last new-build R-1820 was produced in 1964. I think the R-1820 can claim the last new production of the engine types listed above?


I've seen photos of industrial engines derived from the R-1820 which are apparently still in production. If you have a large mine out in the wilderness, you have a GE LM2500 (derived from CF6) turning out 30 MW power. A smaller operation might have the R-1820 derivative driving a generator. Either way, they may have a C-130 with a 3600 gallon tank in the cargo compartment flying in fuel for them.

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## MiTasol (Aug 15, 2022)

Heli Niugini used to fly 4 tonnes of fuel in on sling loads with the Mil-8 helicopters to one gold mine. Early on they used the Mil-26 to sling load fuel in and gold out in shipping containers. The latter containers straight to the ship. Twenty six tonnes max load.

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## Spindash64 (Aug 20, 2022)

BobB said:


> I've seen photos of industrial engines derived from the R-1820 which are apparently still in production. If you have a large mine out in the wilderness, you have a GE LM2500 (derived from CF6) turning out 30 MW power. A smaller operation might have the R-1820 derivative driving a generator. Either way, they may have a C-130 with a 3600 gallon tank in the cargo compartment flying in fuel for them.


Hell, I think there's folks still building parts for US engines specifically to keep warbirds in the air, so depending on how you conclude the Ship of Theseus paradox, the engine never went out of production at all

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## Admiral Beez (Aug 21, 2022)

SaparotRob said:


> Are any of these engines still being made? They must be getting scarce.


I expect Curtiss and P&W radials have readily available or easy to fabricate spares and a small industry keeping them running for both commercial and museum/private aircraft.






Vintage Radials :: Services


Vintage Radials is a FFA certified repair station, VDDR067B, and offers radial engine overhauls, cylinder overhauls, parts and world-wide service.




vintageradials.com





But with far fewer made, a Bristol sleeve valve radial likely doesn't. Though some give it a go, but not for commercial aircraft. 



Bristol Hercules Rebuild











Beaufighter Engine Restorations – June 2022 | Warbirds Online


Beaufighter Engine Restoration News June 2022. Warbirds Online reports on the rebuild of Bristol Hercules engines for the Bristol Beaufighter by Peter Brook



www.warbirdsonline.com.au

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## FLYBOYJ (Aug 22, 2022)

Admiral Beez said:


> I expect Curtiss and P&W radials have readily available or easy to* fabricate spares and a small industry keeping them running for both commercial and museum/private aircraft.*


They don't - but companies with "Parts Manufacturing Approval" or approved Repair Stations may support older Curtiss and P&W products.

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## XBe02Drvr (Aug 22, 2022)

Spindash64 said:


> Hell, I think there's folks still building parts for US engines specifically to keep warbirds in the air, so depending on how you conclude the Ship of Theseus paradox, the engine never went out of production at all


In 1938 the PZL company in Poland took out a license on the Wright R1820 engine, and I believe, continued manufacturing them right up til the end of the cold war.

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## Shortround6 (Aug 22, 2022)

XBe02Drvr said:


> In 1938 the PZL company in Poland took out a license on the Wright R1820 engine, and I believe, continued manufacturing them right up til the end of the cold war.


This gets a bit weird.

Poland may have taken out a license for *A *Wright R-1820 engine 1938 but which one? There are significant differences between the different models.

In 1960 the USSR had Poland start building ASh-62IR as the ASz-62 for Soviet helicopters, agricultural aircraft and later, DHC-3s and DC-3s. 

Since the ASh-62 started as the M-62 which was a modified (?) M-25 which was a licensed Wright R-1820-F3 so there is quite a history of Soviet production of the R-1820 and "improvements" dating back to 1933 and talks starting earlier. 

Soviet engines were supposed to have been converted to metric measurements/standards (Russian book) in the early/mid 30s.

There is no doubt that Poland built R-1820s. The question is which path was followed? 
There is little or no record in the West of Poland building R-1820s in the 40s or 50s. Or indeed much of anything for piston engines until the Mid-late 50s with the WSK WN-3 engine.

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## Admiral Beez (Sep 25, 2022)

PAT303 said:


> A MkII Spitfire or Bf109E-4


Not for their carriers, I don’t think. I think something more like the F4F Wildcat.


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## MIflyer (Sep 25, 2022)

Admiral Beez said:


> I expect Curtiss and P&W radials have readily available or easy to fabricate spares


Well, no, and in some cases parts have been getting scarce for some time.

I recall that around 1979 I read that a company was dealing with the shortage of replacement cylinders for R-1340 engines used in crop dusters and T-6's by taking the much more plentiful R-2800 cylinders and converting them for use in R-1340's. They shortened the cylinders and did what else was needed for the R-1340 use. Note that the R-2800 literally was based on a double stack of R-1340 cylinders, an engine that already had been in use in various applications for almost a decade. Aside from being able to use cylinders that had not been rebuilt over and over, the R-2800 cylinders were based on more advanced technology than the R-1340, giving a more robust engine. 

The R-670 is one of the more popular radials still in use, in Stearman and Waco biplanes. Versions of that engine were also used in M3 Stuart tanks and various landing craft. A man I knew rebuilt R-670 engines by taking the cylinders from the non-aeronautical engines. He could not use the non-aeronautical pistons because they were not suitable; one type was forged and the other was cast. Too late, I realized that he had been hauling the pistons down to the scrapyard and selling them for the value of the aluminum. It suddenly struck me that I could have given him $1.00 each for them, far more than he actually received, mounted them on a suitable wood base, added a plaque describing them as a genuine Stuart tank engine part, and sold them to history buffs for, say, $19.95.

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## XBe02Drvr (Sep 25, 2022)

MIflyer said:


> The R-670 is one of the more popular radials still in use, in Stearman and Waco biplanes. Versions of that engine were also used in M3 Stuart tanks and various landing craft. A man I knew rebuilt R-670 engines by taking the cylinders from the non-aeronautical engines.


We had one of those "resurrected" tank engines at mech school. It was our first strip, rebuild, and run engine before moving on to the R1820, then the Lycoming GO480. As a school run by former Mohawk Airlines victims of the Allegheny takeover, it was clear from that sequence where their priorities lay. They loved the old CV440s and Martin 404s and regarded kerosene burners with distaste.

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## MiTasol (Sep 26, 2022)

Kerosine burners? Don't you mean suck and blow tin cans?


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## GrauGeist (Sep 26, 2022)

AAF guys during WWII called the the German jets "blow jobs".

Just putting this out there for what it's worth...

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## XBe02Drvr (Sep 26, 2022)

MiTasol said:


> Kerosine burners? Don't you mean suck and blow tin cans?


Well, you could put it that way, I suppose. These guys never made it to the BAC 1-11 with its "tin can" Speys. They were still on the "whistlepig" FH227s with their screaming RR Darts and pining for their beloved R2800s when the airline collapsed around them and "Agony Airways" took over. Allegheny tried to avoid a culture clash by offering ex Mohawk employees jobs, but dispersing them to the far reaches of their system and filling all the central NY jobs with their own transplants and new hires. Presented with far away jobs and no relocation allowance, many Utica - Syracuse Mohawk employees quit and left the industry, only to come back a decade later when Utica spawned yet another wildfire growth airline, Empire, which became part of Piedmont, then USAir, and finally, American. One of my former students started on Navajos with Valley Air Service, which became Empire, and retired last year from American, after being typed in every jet that series of airlines flew. His license had two pages to list all his ratings.

PS: As a former RR Dart "victim" myself, I can sympathize with their distaste for the Whistlepig. It certainly was a different sort of beast.

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## MIflyer (Sep 26, 2022)

XBe02Drvr said:


> We had one of those "resurrected" tank engines at mech school.


Some actually hung the tank engines on airplanes. A friend of mime found out that a outfit in Southeast Florida had an R-670 available at an attractive price. He drove down in his pickup and bought it. On the way at home, he started thinking and realized that the engine's crankshaft looked suspiciously short. He turned around, went back, and confirmed it was a tank engine, got his money back.

And maybe 23 years ago there was an ad in the The Ercoupe Club newsletter. Someone had a RR Griffon for sale for about $1700. A friend of mine, an accomplished Army aviator, said he wish he had known since he would have bought it, to use as a coffee table in his house, if nothing else.

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## XBe02Drvr (Sep 26, 2022)

MIflyer said:


> Some actually hung the tank engines on airplanes. A friend of mime found out that a outfit in Southeast Florida had an R-670 available at an attractive price.


There was a guy in Amish PA who bought a wharehouse full of the tank version and put aircraft splined shafts and surplus aircraft cylinders on and advertised in_ Trade-a-Plane_ and _Sport Aviation _(EAA) _"Every biplane deserves a radial!". _An acquaintance of mine wanted to re-engine his PT23 and got all excited until he discovered those PA engines could only be used in Experimental Category aircraft.


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## BobB (Sep 26, 2022)

MIflyer said:


> Well, no, and in some cases parts have been getting scarce for some time.
> 
> I recall that around 1979 I read that a company was dealing with the shortage of replacement cylinders for R-1340 engines used in crop dusters and T-6's by taking the much more plentiful R-2800 cylinders and converting them for use in R-1340's. They shortened the cylinders and did what else was needed for the R-1340 use. Note that the R-2800 literally was based on a double stack of R-1340 cylinders, an engine that already had been in use in various applications for almost a decade. Aside from being able to use cylinders that had not been rebuilt over and over, the R-2800 cylinders were based on more advanced technology than the R-1340, giving a more robust engine.
> 
> The R-670 is one of the more popular radials still in use, in Stearman and Waco biplanes. Versions of that engine were also used in M3 Stuart tanks and various landing craft. A man I knew rebuilt R-670 engines by taking the cylinders from the non-aeronautical engines. He could not use the non-aeronautical pistons because they were not suitable; one type was forged and the other was cast. Too late, I realized that he had been hauling the pistons down to the scrapyard and selling them for the value of the aluminum. It suddenly struck me that I could have given him $1.00 each for them, far more than he actually received, mounted them on a suitable wood base, added a plaque describing them as a genuine Stuart tank engine part, and sold them to history buffs for, say, $19.95.


The R-670 tank engines had two different type pistons, one of which could be used on aircraft. Stoltzfus would x-ray one cylinder on each engine to determine which piston was installed as he could sell an engine with aircraft pistons for more money. A Curtiss-Wright employee told me that they couldn't just scrap their sodium filled exhaust valves since the sodium would burn/explode when dumped in a smelter. They were mounting them on plaques noting that they were from the engines used on B-17 bombers and giving them away to customers. When they lost their last military customer for engine parts, they scrapped a warehouse full of engine parts as their wholesale value wasn't worth the liability exposure.

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## tomo pauk (Sep 27, 2022)

Shortround6 said:


> They could prioritize whatever they wanted.
> 
> Without the needed engines they were stuck.
> 
> The Ki-44 started with a 1260hp engine at 12,149ft with a single speed supercharger, repeat, single speed.



Late to the party, but anyway 
A 1260 HP engine at 12150 ft is perhaps not that big amount of power, but it still means a 30+% increase over the Ha-25 installed on the Ki-43. Single speed S/C on a fighter in 1941-42 is not a bugaboo.



Shortround6 said:


> The two speed engine using the same cylinders didn't show up until the summer of 1942 in prototypes. In the fall of 1942 in pre production and in Nov 1942 in actual production.
> The two speed engine 1440hp at 7,000ft and 1320hp at 17,220ft.



The Ha 109 was delivered in 22 examples in 1941, 645 were delivered in 1942 (double digits production from April, triple digits from October). Note that altitude power was better than on the BMW 801C, with 2/3rds of the weight, a bit smaller size, and a far better reliability; yes, 801 has the better exhausts, but also the worse intakes.



Shortround6 said:


> But until you have the improved engine with the 2 speed supercharger you are stuck.



It is far better to be stuck with a Ha 41, than with the Ha 25. But, for better or for worse, Japanese were betting on the wrong horse (not just here).
Of course, the Kasei is in series production at the competition...


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## Shortround6 (Sep 27, 2022)

tomo pauk said:


> Late to the party, but anyway
> A 1260 HP engine at 12150 ft is perhaps not that big amount of power, but it still means a 30+% increase over the Ha-25 installed on the Ki-43. Single speed S/C on a fighter in 1941-42 is not a bugaboo.



Well, the start of this part of the thread was

"prioritized protection, firepower and speed over agility and endurance".

Yes 1250hp at 12,150ft is not bad in 1941-42 compared to the 1150hp at 11,500ft (or close) from the P-40E but the P-40E didn't work out all that well without a little help. 
Like over-boosting and other allied aircraft to share the sky with. 

Fortunately the Ha 109 showing up in numbers in 1942. Unfortunately the Japanese did not make very good use of it, still betting on the agility and light armament. 

The Homare showed up too late, if the Japanese wanted to prioritize protection, firepower and speed they needed to do it before late 1943 in trickles. 
For radial engines that means the Nakajima Ha 109, the Mitsubishi Kinsei and Kasei and the Kinsei is a bit suspect as to timing. You really need the 60 series engines.

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## MiTasol (Oct 26, 2022)

How to improve the Spitfire is covered in a document at the IWM Notes on Suggested Improvements to the Spitfire, September 1940

Page 3 is below and some of these like 1 to 3 and 8, 9 & 12, are so blindingly obvious that one has to ask why a pilot had to tell the AM that these were needed. Maybe because the AM decision makers were mentally still in Sopwith Camel land where they never fought at altitudes where oxygen was needed and they didnt have cockpit heat so why should these young bucks have it.

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## Admiral Beez (Oct 28, 2022)

Three twin engined ground attack aircraft I’d put forward in need of improving….

Breda Ba.88 Lince
Bréguet 693
Henschel Hs 129


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## Shortround6 (Oct 28, 2022)

Admiral Beez said:


> Three twin engined ground attack aircraft I’d put forward in need of improving….
> 
> Breda Ba.88 Lince
> Bréguet 693
> Henschel Hs 129


And strangely enough the last two used the same engines. 
Better engines may have saved (or at least made it so it didn't suck as much) the Ba.88

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## FLYBOYJ (Oct 28, 2022)

Admiral Beez said:


> Three twin engined ground attack aircraft I’d put forward in need of improving….





Admiral Beez said:


> Breda Ba.88 Lince


It was improved - by making it a target decoy.


Admiral Beez said:


> Bréguet 693


Potential


Admiral Beez said:


> Henschel Hs 129


Hard to improve an aircraft that was designed to be shot at


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## FLYBOYJ (Oct 28, 2022)

Shortround6 said:


> And strangely enough the last two used the same engines.
> *Better engines may have saved (or at least made it so it didn't suck as much) the Ba.88*


And this:

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## GrauGeist (Oct 29, 2022)

Considering that the Hs129 started out with Argus 410 engines, the G-R 14 series was a great improvement.

The problem with upgrading engines, is they weigh more. The G-R Mars weighed just under 1,000 pounds, the closest alternative would be perhaps the BMW132, which weighed about 1,150 pounds - but to what advantage?

The Germans kept loading bigger weapons on the 129, up to the BK7.5, which was far too heavy for the airframe.

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## WARSPITER (Oct 29, 2022)

I used to think the HS 129 wasn't much chop but I've since changed my mind as it was yet another victim of the 
STBR syndrome that was a real problem throughout the war for the Wermacht as a whole.

I call it STBR for Soon To Be Replaced syndrome. There were supposed to be new planes, subs, tanks and so forth always coming
but it was always a case of too little too late or too many design / mechanical faults and delays in the new stuff.

The 129 was supposed to be replaced by the ground attack version of the FW 190 but with the other requirements for that aircraft
the numbers were never enough.

Kursk proved to be a lesson in this as the 129 did well at the start but the overall lack of ground attack planes meant rear areas were
virtually untouched. As soon as the Soviets realised this large amounts of anti aircraft guns were moved forward and caused real
problems for the Luftwaffe ground attack planes. 

The 129 became more vulnerable as time went on not due to it being a bad aircraft but due mainly to STBR.

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## GrauGeist (Oct 29, 2022)

The Hs129 was not "supposed to be replaced" by the Fw190, the Hs129 was one of the first, purpose-built ground attack aircraft made.
The Fw190 was intended to be a fighter, not a ground attack platform - apples and oranges.

The main issue of the Hs129 was not it's ability to subdue AFVs, it was the inability of the Luftwaffe to provide air superiority within it's operation radius.


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## WARSPITER (Oct 29, 2022)

I was thinking of th eFW 190 F and G series which were specific modifications for ground attack and highlight the problems 
the Luftwaffe had in the war with keeping up when so many roles were required.

Again the 129 suffered from a lack of further development.


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## Admiral Beez (Oct 29, 2022)

GrauGeist said:


> the Hs129 was one of the first, purpose-built ground attack aircraft made.


Isn’t that a claim all three could make?


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## buffnut453 (Oct 29, 2022)

Hey look...I've been able to drastically improve the Breda Ba.88. It actually wasn't that difficult in the end:







It's my coat and I'll wear it if I want to...wear it if I want to... etc.

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## GrauGeist (Oct 29, 2022)

Admiral Beez said:


> Isn’t that a claim all three could make?


The Ba.88 started life as a "heavy fighter bomber".

Breuget's 690 series started out as a twin engine fighter design.

The Hs129 was a submission to the RLM's request for a dedicated ground attack platform and it was a clean-sheet design.

Even Focke-Wulf took an existing type (Fw189) and modified it as a submission to the RLM's request: Fw189 V6 (Fw189C).

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## Admiral Beez (Oct 29, 2022)

GrauGeist said:


> The Hs129 was a submission to the RLM's request for a dedicated ground attack platform and it was a clean-sheet design.


I wonder what Henschel would have made had the spec in addition to the armoured cockpit, been built around a pair of BMW 801s and a pair of integral 30mm MK 101/103 cannons along with large ammunition capacity. Something larger than the Hs129, perhaps like a short span Focke-Wulf Fw 187?


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## GrauGeist (Oct 30, 2022)

The Fw187's wingspan was only 8 feet wider than the Hs129's.

The 129 was a solid concept, it just lacked good speed - but that was also an issue, as it's controls became very heavy as it built up speed in a dive.

As brilliant as Kurt Tank was, his submission (the modified Fw189) was a disappointment.

It would have been interesting to see what Heinkel or Junkers could have come up with if they had done a clean sheet design.


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## tomo pauk (Oct 30, 2022)

GrauGeist said:


> Considering that the Hs129 started out with Argus 410 engines, the G-R 14 series was a great improvement.
> 
> The problem with upgrading engines, is they weigh more. The G-R Mars weighed just under 1,000 pounds, the closest alternative would be perhaps the BMW132, which weighed about 1,150 pounds - but to what advantage?
> 
> The Germans kept loading bigger weapons on the 129, up to the BK7.5, which was far too heavy for the airframe.



Germans could've used the Polish-made Mercury engine on the Hs 129. Still 1000 lbs, a bit better power than the 14M - even down low - but the main advantage over the 14M series is that re-engining can be done some 9 months earlier, so the resulting aircraft is fully debugged by late 1940, instead of late 1941.

The BMW 132 (and the Bramo 323) could've been mated to the Ju 87. The bigger 14N too, as well as on the Bf 109, or the original, small-wing Fw 190.


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## yulzari (Oct 30, 2022)

tomo pauk said:


> Germans could've used the Polish-made Mercury engine on the Hs 129


Does anyone know what became of the Polish engine factory? One would have thought that the Germans could have found some uses for Mercuries and Pegasus.


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## Shortround6 (Oct 30, 2022)

yulzari said:


> Does anyone know what became of the Polish engine factory? One would have thought that the Germans could have found some uses for Mercuries and Pegasus.


Perhaps, or perhaps the factory was looted (machine tools sent to German).
The factory was not big, or at least not big in the early 1930s. The factory built 200 (?) Mercury engines for the PZL 11 fighters in the Early 30s at the rate of 20 engines per month.
The Factory was building Pegasus engines in the late 30s, primarily for the PZL 37. 
How much subcontracted was used I don't know. The Polish factory was at least (if not mostly)owned by Skoda in Czechoslovakia. Casting, at least in the 1920s and early 30s came from subcontractors. As aviation technology advanced in the 1920s and 30s they sometimes found they were unable to make new engines because they needed new tooling/machine technology that the older engines did not use.

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## Shortround6 (Oct 30, 2022)

Admiral Beez said:


> Three twin engined ground attack aircraft I’d put forward in need of improving….
> Henschel Hs 129





GrauGeist said:


> Considering that the Hs129 started out with Argus 410 engines, the G-R 14 series was a great improvement.



The idea of "improving" the Hs 129 needs to stay inside of some strict limits.
The whole idea of the Hs 129 was to use small, cheap engines that would not conflict with the production schedules of the normal high powered aircraft engines. 
With the required armor it turned out that small engines didn't have enough power (the FW 189 with armored nacelle was also vastly underpowered).

Once you are competing with Do 17Zs or Ju 52s for engines the rational for the Hs 129 is running into trouble. 

The access to the GR 14M engines pretty much saved the program, the engines were small, offered 50% more power, and didn't use _any_ German production capacity. 

Did I mention *small*? 
The GR 14M was under 1 meter in diameter. A Mercury was about 350mm larger in diameter. A much bigger target and a lot of the increased power is going to get used up by fighting the extra drag ( same for the Bramo 323 and BMW 132 which are a bit bigger than the Mercury) 

Plane carried 134imp gallons of fuel (610 liters) 
Range clean at economical cruise speed was 428 miles, with 30mm MK 103 cannon range was 348 miles. 

If you started with a clean sheet of paper you could come up with a more capable attack plane than the Hs 129, but it would be bigger, heavier, cost a lot more, use more fuel and require engines needed for other things or GR-14N engines. Or ever _3 HS 129 Supers_ means one less Me 323

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## Admiral Beez (Oct 30, 2022)

Shortround6 said:


> Or ever _3 HS 129 Supers_ means one less Me 323


How can we modify the Me 323 for ground attack or CAS? The Me 323E-2 WT might be a good place to start.


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## Thumpalumpacus (Oct 30, 2022)

Shortround6 said:


> Or ever _3 HS 129 Supers_ means one less Me 323



You say that like it's a bad thing!


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## GrauGeist (Oct 30, 2022)

Thumpalumpacus said:


> You say that like it's a bad thing!


Well...from the Luftwaffe's point of view, it would be!

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## Kilkenny (Nov 2, 2022)

- A6M with a Kinsei engine from the outset (ala A6M8), allowing more pilot armor and at least one self-sealing fuel tank
- Ki-61 with a Kinsei engine from the outset (ala Ki-100) - eliminating a need for the Ki-43; Ki-43, Ki-61
- Ki-46 with a Kinsei engine from the outset - allowing more time to develop a better high-altitude supercharger
- NIK2 Shiden-Kai with a Kasei engine instead of the Homare and lower winger/stronger undercarriage
- J2M Raiden given priority status to be both the IJN and the IJA's B-29 interceptor starting in 1943

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## BarnOwlLover (Nov 9, 2022)

This isn't specific to one aircraft, but which designs could've benefited the most from spring tab ailerons and/or powered ones? I sort of knew that the Hawker Tempest and for sure the Sea Fury used spring tabs, and surprised to learn that the Supermarine Seafang used powered ailerons. 

Also, specific to actual aircraft, I would've made the Hawker Typhoon and Tempest all-moncoque (like the Fury/Sea Fury), and I'd have proceeded with making the Spitfire's nose more streamlined, and looked to see how much a ventral Meredith radiator or at least an improved radiator solution would've helped reduce drag.


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## nuuumannn (Nov 9, 2022)

Sounds adventurous, but futile, as with all the effort required to do this, you might as well design a new aeroplane from scratch. The Spitfire's design precludes any Meredith radiator fuselage installation, there's no way, without redesigning the fuselage it could be done as it existed. This would mean stoppages of production and the gaps at the frontline that that meant, whereupon Griffon engined Spitfires could have equalled the results expected from the modifications proposed. In hindsight, the effort to do so would have been needless and would not have offered as much of an advantage to the Spitfire as you might think, although without comprehensive charts etc, that can't be known exactly, but could it produce an aeroplane that could out-perform what the Spitfire became with the fitting of two-speed two-stage Griffons? It's hardly worth the effort. Martin Baker's MB.5 is probably the closer to what you might be thinking of from a Biritsh standpoint. The Griffon engined Spitfire proved the airframe could remain at the forefront of fighter performance that didn't take enormous and extensive refabricating of the basic design.

It's still a Spitfire...





Spitfire static-9

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## Shortround6 (Nov 9, 2022)

Look at the area of the radiators, intercoolers and oil coolers in those two ducts. 
Now figure out how to combine them into one under fuselage duct. 
P-51 hid about 1/2 of the radiator matrix inside the fuselage and about 1/2 inside the duct. 

This is something that has to be designed in, not added later. Unless you have lots of time to redesign that area of the fuselage and redo the tooling (jigs/fixtures)

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## GrauGeist (Nov 9, 2022)

There was also a fuel tank behind the Spitfire's cockpit (one of two) which would have been in the way of a P-51D style radiator system.

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## BarnOwlLover (Nov 10, 2022)

How about a "Westernized" MiG I-225?



Mikoyan/Gurevich I-225 - fighter





Mikoyan and Gurevich I-225








MiG Fighter Aircraft Development WWII


I-211 After operational tests of the MiG-3 powered by the M-82, produced in a small batch of five aircraft designated MiG-9 M-82, one ...




soviethammer.blogspot.com





What's there is pretty good by Soviet standards and late World War II standards overall, and, aside from some engine issues, the aircraft performed well.

But here's changes I'd make to it.

Replace the AM-42 (a 46-47 liter engine) with a Rolls Royce Griffon (more power and lighter weight) or a Merlin (lighter still and similar power to the AM-42).

Doing the latter also gets rid of the troublesome turbo and replaces it with a two stage supercharger. The Griffon and Merlin also would be more economical in terms of fuel economy, which means either longer than the 800 mile range it got with the AM-42, or less fuel for similar range.

Replace the ShVAK 20mm cannons with Hispano-Suiza Mk Vs like on the Hawker Tempest and later Spitfires (sadly, there's no known Western equivlant to the B-20 cannons, which weighed about the same as a AN/M2 or AN/M3 .50 MG).

Move the cannons from the fuselage to the wings (more ammo capacity and more room for fuel in the fuselage).

Possibly go for a wing with wider span and lower aspect ratio.

Get the type rated for underwing stores (like drop tanks, bombs or rockets)

And for both aero and ascetic reasons, widen the spinner and smooth the engine cowling.

I'd also see about getting rid of that ventral intake. I've variously read that it's an oil cooler or maybe the turbo's intercooler. If using the Merlin or Griffon it might be able to go away if it's indeed the intercooler.

And put fully enclosing doors over the main wheels of the undercarriage.


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## tomo pauk (Nov 10, 2022)

Is the stenciling on the gauges & cockpit still metric & cyrilic (where applicable)?

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## XBe02Drvr (Nov 12, 2022)

BarnOwlLover said:


> Possibly go for a wing with wider span and lower aspect ratio.


If you're calling for wider span and lower aspect ratio, you're calling for a huge increase in wing area. Or did you mean a wider *chord *and lower aspect ratio?


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## BarnOwlLover (Nov 12, 2022)

Larger wing area to decrease wing loading, which was an aim of the Mitsubishi A7M and similar IJA/IJN fighters as they got larger and more powerful.


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## XBe02Drvr (Nov 12, 2022)

BarnOwlLover said:


> Larger wing area to decrease wing loading, which was an aim of the Mitsubishi A7M and similar IJA/IJN fighters as they got larger and more powerful.


Comes at the price of less speed and a loss in climb performance. All that extra wing area costs you in induced drag. You gain turn rate performance at the cost of speed, climb rate, and energy decay in high G turns.

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## BarnOwlLover (Nov 30, 2022)

How about a Spitfire with Spiteful-type radiators and inward retracting landing gear?


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## XBe02Drvr (Nov 30, 2022)

BarnOwlLover said:


> How about a Spitfire with Spiteful-type radiators and inward retracting landing gear?


Great idea, but what are you going to do about the much thicker airfoil the supporting structure for that landing gear will require, as well as the repositioning of the wing guns outward? Remember, the designer of the Hurricane later lamented the thick wing he saddled her with, in pursuit of simpler structural design. With a thinner airfoil, the Hurri might have been closer to the Spit in performance.


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## wuzak (Nov 30, 2022)

If I remember correctly, the Spiteful's wing was thinner than the Spitfire's. And the guns were just outside the propeller arc.


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## tomo pauk (Nov 30, 2022)

BarnOwlLover said:


> How about a Spitfire with Spiteful-type radiators and inward retracting landing gear?



Shallower and wider radiators were use on the Spiteful, so I agree with the proposal. Inward-retracting U/C might not went well with the propeller diameter, since, due to the Vee of the wing, ground clearance will be lower for the same length of U/C legs.
I'm not sure that Spitfire have had that much of the problems due to the main U/C retracting outwards.

One thing the late marque Spitfires have had was the fully retractable and covered U/C, that might gain another +-10 mph vs. what Spitfire IX had?


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## BarnOwlLover (Dec 2, 2022)

Which one of these would be best to make an even better P-51 Mustang:

1: Modify it to be built to British design standards with product improvement upgrades and same Packard Merlin engines (XP-51F),

2: Keep the basic B/C/D/K airframe and hope for the Merlin 100 or V-1650-9/11 engines (A Mustang III/P-51B was tested with a Merlin 100 engine, and at a take off weight of 9600-9700 lbs reached 455 mph top speed and an initial climb rate of 4300-4400 fpm per RAE report), or,

3: Do both and get the P-51H/L/M into production quicker?

It should be noted that the FW-190 for example 2, with the BMW 801, weighed almost 10,000 lbs max take off weight, the FW-190D and Ta-152H had a normal "clean" take off weight of 9400 or so lbs. But all (even the Ta-152) had significantly less range on internal fuel than the P-51. We know from the P-51H and the XP-51F/G that the B/C/D/K were kind of overbuilt, but I wonder how "overbuilt" the FW-190 was, given it's weight vs fuel capacity/range, and that a standard Merlin Mustang could climb as fast or faster initially than the FW-190 or Ta-152 initially.


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## BarnOwlLover (Dec 16, 2022)

Also, is there a way that anyone knows of to make the DH Hornet have agility similar to the P-38?


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## WARSPITER (Dec 16, 2022)

BarnOwlLover said:


> Also, is there a way that anyone knows of to make the DH Hornet have agility similar to the P-38?


Only fly it on one engine ?

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## tomo pauk (Dec 16, 2022)

BarnOwlLover said:


> Also, is there a way that anyone knows of to make the DH Hornet have agility similar to the P-38?


What is posted just above is pure gold - it was P-38 that needed to up it's game, not the Hornet.


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## BarnOwlLover (Dec 16, 2022)

I did read in Tony Buttler's book about the Hornet that it's maneuverability, especially roll rate, wasn't great. However, it was compared to single seaters, like the Spitfire, Mustang and even the Vampire. Later P-38s did have powered ailerons, and even early versions were attested by German pilots as being able to out-turn them, though their roll rate until the powered ailerons came in was relatively poor.

Based on Buttler's book, I can't see the Hornet as out-turning most German single seaters, though it could climb much faster than most and was much faster. Same applies vs the P-38.

Of course, I do wonder how the F-82 compared to the Hornet.


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## XBe02Drvr (Dec 16, 2022)

BarnOwlLover said:


> Later P-38s did have powered ailerons, and even early versions were attested by German pilots as being able to out-turn them, though their roll rate until the powered ailerons came in was relatively poor.


The P38 was an older design, dating back to early days of all metal monoplane fighters, and had more of a high lift airfoil (hence its compressibility and critical Mach issues). This, plus it's high thrust available allowed it to sustain a high G turn with less energy bleed than a less powerful single seater with a thinner, more speed-oriented wing, at dogfight speeds. Add a combat flap, and the turning advantage increases. 
Any multi engine fighter (other than centerline thrust) is going to suffer a penalty in roll rate, due to the polar moment of its distributed mass. The effects of this penalty are going to depend on the strength of the roll moment the ailerons, spoilers, or other roll control devices can generate. On the face of it, it would appear the F82 might have more laterally distributed mass than either a Hornet or a Lightning. So, did NA compensate for this in designing the twin pony's roll controls? Can two hands on two sticks generate enough additional roll authority to compensate for the distributed mass?
Stay tuned.

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## BarnOwlLover (Dec 16, 2022)

F-82s used asymmetric boosted controls linked to each pilot's stick due to trying to roll the plane about an asymmetric axis. I don't know if this had any positive effect on roll rate.


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## tomo pauk (Dec 16, 2022)

XBe02Drvr said:


> The P38 was an older design, dating back to early days of all metal monoplane fighters, and had more of a high lift airfoil (hence its compressibility and critical Mach issues).


Wing on the P-38 have had the 16% t-t-c at root (NACA 23016). This is same as P-47, whose compressibility problems were much less severe.
The F4U was at 18% (NACA 23018), F8F was at 19% - again less issues with high-speed dives.
NACA stated also the steep windscreen and abrupt ending of the pod as culprits for the low compressibility limit.
Granted, compressibility was better known a problem when P-38 entered service, than it was the case when it was being designed.

Manual for the P-38 notes that a lot of the compressibility problems were due to the pod and nacelle creating a venturi (obviously x2 per aircraft), that made the airflow speed up.

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## BarnOwlLover (Dec 17, 2022)

Granted, making a twin as agile as a single seater is almost always a tall task, but could anything be done to make the Hornet even better in that aspect?

Also, would handed engines (like on the Hornet) have been of much use on the Mosquito beyond being a bit of a quality of life improvement for the pilot?

And for a plane like the Mosquito (or any other similar SHTF combat planes of World War II, like several promising French designs), what would've been better, the Mosquito's construction method, the use of Duramold wooden construction, or a mix of both?


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## tomo pauk (Dec 17, 2022)

BarnOwlLover said:


> Granted, making a twin as agile as a single seater is almost always a tall task, but could anything be done to make the Hornet even better in that aspect?



ADI for the engines, powered controls (at lest ailerons), Fowler flaps?


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## ThomasP (Dec 17, 2022)

Duramold composite is significantly more dense than the plywood/balsa/plywood sandwich and solid wood structure used on the Mosquito.

But, at least in theory, the phenol impregnated plywood structure of the Duramold type would have needed a lower safety factor due to its mooted lower probability of crack propagation. It would also probably have survived adverse climate conditions better than the Mosquito structure.

Unfortunately, there were only 2 airframes (I think) made ~entirely of Duramold - the Fairchild F-46A and the Hughes H-4 Spruce Goose so there is very little information as to how successful the material would have been during the WWII era. The Spruce Goose came out grossly overweight and only flew once for a very short distance, so the F-46A is the only airframe that was flown to any extent (~20 years??). I have never been able to find any flight test or structural strength/fatigue assessment data for the F-46A.

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## Shortround6 (Dec 17, 2022)

BarnOwlLover said:


> And for a plane like the Mosquito (or any other similar SHTF combat planes of World War II, like several promising French designs), what would've been better, the Mosquito's construction method, the use of Duramold wooden construction, or a mix of both?


Kind of depends what you want to do. 
The Mosquito was not stressed for fighter style maneuvers. I believe the practical limit was about 6 Gs ? 
If you want the same plane to act like a fighter you need a stronger structure Which means more weight and less internal volume (keeping the same external shape/drag).
You also have to have the Material to actually build the desired aircraft in quantity. Classic case the Langley Twin. 





Note that even the cowls were made of laminated molded wood. Very few metal fasteners were used. 
However even this small twin needed over 50 gallons of vinyl and phenol resins and the amount of resins needed turned out to be in shorter supply than metal. 
One account of the French aircraft says that only about 10% of the purchased spruce wood was suitable for aircraft construction. And the French had no suitable domestic Spruce, it all had to be imported. You can't sort the spruce wood until the tree is cut and sent through the sawmill and then it needs drying. 
Getting wood you can make a spar for 350mph airplane that will pull (repeatedly) 6Gs is a whole lot different than building a spar for a 175mph airplane that pulls 3.5 Gs. 
Duramold was used for a lot of small parts for aircraft as it was. Crew seats, bulkheads, hatches, non stress panals.

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## BarnOwlLover (Dec 17, 2022)

This would probably be better suited for it's own thread, but is there any other materials other than wood and metals (namely aluminum and steel alloys) that can be viable for use for aircraft that's "non-strategic"? Such as something like Aerolite or something else that might have been explored?


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## ThomasP (Dec 17, 2022)

A couple of forms of fiber-glass were experimented with as early as the WWI period, but making the consistency/quality of glass fiber and the resins needed was difficult/expensive for the time. Plus wood and aluminum (once the cost of production went down) worked well enough.


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## yulzari (Dec 17, 2022)

The Spitfire had a fuselage made of Gordon Aerolite flax and resin material in lieu of aluminium in 1940





AN ORGANIC SPITFIRE? - Fighters Under Construction in World War Two: Rare Photographs from Wartime Archives


AN ORGANIC SPITFIRE? - Fighters Under Construction in World War Two: Rare Photographs from Wartime Archives - by Graham M. Simons




erenow.net

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