# Re-engined planes



## tomo pauk (Mar 18, 2010)

Since my skills in M$ Paint are growing exponentially, here are some sqetches of good planes, re-engined with different engines.
P-38 with R-2600 (2 x 1600 HP feasible in 1941, 1750 year after that, 1900 HP in 1944) - perhaps the fastest piston job, plus suddenly the A-20, B-25, B-26, A-26, P-61, F-7F became redundant. Note that oil coolers are now where turbo is for plain P-38s located:


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## Waynos (Mar 18, 2010)

I was thinking of something similar yesterday, When we discuss the Westlad Whirlwind the subject of re-engining it with the Merlin always crops up, however looking at a Gloster book yesterday I saw the Peregrine and Taurus powered versions of the Reaper, so, I wondered, how about a Taurus Whirlwind? Any chance you could oblige?


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## Colin1 (Mar 18, 2010)

Waynos said:


> When we discuss the Westland Whirlwind the subject of re-engining it with the Merlin always crops up...


The problem with just dropping Merlins in was that the Whirlwind was really built around the Peregrine and its sparing dimensions just didn't lend themselves to a bigger powerplant. They tried with the Welkin using the Merlin 76 but its primary reason for existing in the first place disappeared when Spitfire HF.VIs made it clear that the Ju86 could no longer range with impunity over SE England.

The Welkin also had one or two compressibility issues but that's digressing a little.


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## tomo pauk (Mar 18, 2010)

Hmm, lets see about Gloster F.9/37: (aka Reaper):
-fastest combat-ready plane when flown (early '39)
-well armed
-able to take punishment (two radials)
-capability for great range (pilot cabin in front, generous internal volume)

And they scrapped it. Well done 

Now back to your question - yes, the Whirlwind with same/similar engines would be just as good plane. While the Peregrines received much criticism, the same engines powered the Whirlies 'till late '43 - not such troublesome engines in my eyes.


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## Colin1 (Mar 18, 2010)

Griffon-powered P-38
5-bladed Hamilton hydromatic screws and radiator air scoop arrangement a la P-51 (1 per nacelle)
Nose battery of 4 x 23mm Madsen cannons

That would shake an Me262 up


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## Waynos (Mar 18, 2010)

Colin1 said:


> The problem with just dropping Merlins in was that the Whirlwind was really built around the Peregrine and its sparing dimensions just didn't lend themselves to a bigger powerplant..



That was my thinking when opting to look at the Taurus, that fitted ok onto the Gloster which was also designed for the Peregrine. And thanks for fixing my typo in the quote 



tomo pauk said:


> Hmm, lets see about Gloster F.9/37: (aka Reaper):
> -fastest combat-ready plane when flown (early '39)
> -well armed
> -able to take punishment (two radials)
> ...



Yes, true genius, lol.

And yet we did put the Defiant into production!

I have often wondered how this aircraft would have fared if produced. For one thing it would mean no Blenheims in FC possibly. But I digress. I also found a photo of a Griffon Beaufighter the other day. That was a surprise.


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## tomo pauk (Mar 18, 2010)

Anyway, here is the 'new' P-51R (=radial). 
R-2800 aboard, with 2000 hp (well above 700 km/h) until early 1945 - then 2450 HP (for beyond 750 km/h), as in F-4U4. No turbo, sorry P-47 lovers (like me). F-4U is for comparison here:

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## tomo pauk (Mar 18, 2010)

The 5-engined B-17, as discussed in thread about twin hulled planes.

The XB-38 - B-17 with 4 turbo-charged Allison engines, was capable for 530 km/h, and service ceiling was beyond 36 kft. The plane I propose would use the 5th engine (located just aft the bomb bay) to supercharge the other 4 engines, a system used in real Do-217P (one DB-605 supercharging two larger DB-603s). The weight increase would be remedied by deletion of all MGs (13 pcs in B-17G, above 80lbs each, tot more than 1000 lbs), 5 crew members less ( x 200 lbs with gear = 1000 lbs), MG ammo, armor. The deletion of 3 prominent turrets and other MGs would also reduce the drag, so I hope that plane would be able to do 600 km/h max, above 40 kft.


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## Shortround6 (Mar 18, 2010)

As usual the question is how much power at what altitude?

The next question for replacing bombers is the range. Late model P-38s with fuel tanks were the old inter coolers were carried 410 gallons of internal fuel. that is not going to go far feeding R-2600s. 

Some versions of the B-25s could carry over 1100gals of fuel I believe while still having some room in the bomb bay. Perhaps a 2000lb bomb load while carrying that much gas.

The lower drag of your radial P-38 will help somewhat but I doubt it is going to get 2 1/2 times the miles per gallon of the bombers while toting a ton or more of bombs.

While you have a good power to weight ratio for lifting a war load your wing loading is going to really stink.


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## tomo pauk (Mar 19, 2010)

The additional fuel tanks would been carried in place once occupied turbocharger and cooler plumbing (from middle of boom, towards the engine), so the inboard pilons would remain free. 
Yep, wing loading would suffer, not so much compared with A-20  Will come with numbers shortly.


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## tomo pauk (Mar 19, 2010)

WIng loadings for max take off weights, late versions (not A-26, but still..), in lbs/sqft, data from Wiki:

B-26: 58 (5300 built)
A-20: 58,5 
P-47N: 64 (included for comparison of wing loading - data from my book about US planes)
A-26: 65 (1000 built till VE day?)
P-38: 66 (10 000 built)
B-25: 68 (10 000 built)

The P-38 w/ R-2600 dwarfs all of them in power loading, as admitted.

The other benefits include that 3 such P-38s could've been built for every pair of B-25s, and 2 per each B-26 and A-26. The crew needed would've shrunk from 3 to 7 times (perhaps a major benefit), if the planes would be issued 1 on 1 basis vs. the planes from comparison of this post (not vs P-47N). The air commander would have the possibilty to launch a thousand or two fighters, then same number of bombers, or same number of anti-shipping strikes.


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## tomo pauk (Mar 19, 2010)

Fw-187 Falke, with Italian radial engines (2 x 840 HP Fiat A.74, good for 550 Km/h, or 2 x 1000 HP Piaggio P.XI, just under 600 km/h clean), depicted here with 30mm for tank busting:


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## tomo pauk (Mar 19, 2010)

Waynos said:


> I was thinking of something similar yesterday, When we discuss the Westlad Whirlwind the subject of re-engining it with the Merlin always crops up, however looking at a Gloster book yesterday I saw the Peregrine and Taurus powered versions of the Reaper, so, I wondered, how about a Taurus Whirlwind?* Any chance you could oblige?*



Sure, here 'tis 
(Damn, those wings are thin - guess we have add some jet engines in place of piston engines)


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## tomo pauk (Mar 19, 2010)

... and here is the Whiry with jet engines. The nose got some volume and different shape to accommodate nose wheel strut, along with ammo for, now, belt-fed cannons. The extension would've also cancel out the dis-balance caused by engine removal.
The main undercarriage is attached to aft spar, retracting inward. The jet version would've been even lighter - RR Welland weighted some 300 lbs less then RR Peregrine, and prop, gearbox and radiators are not needed here. So perhaps 1000 lbs less because of jet engines, and added 200-300 lbs for nose wheel and more ammo - bottom line 700-800 lbs less for empty weight, 7-8% saved.
Feasible in 1941.


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## Colin1 (Mar 19, 2010)

tomo pauk said:


> ... and here is the Whirly with jet engines.
> Feasible in 1941.


I don't think much of the new pilot visibility.
Unlikely any time.


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## tomo pauk (Mar 19, 2010)

Yep, pilot would've seen nothing, got to redesign it 

Too bad you think pioneers of jet technology would've skip it 8)


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## tomo pauk (Mar 20, 2010)

The defender of free world - P-40. 
The most criticized part of plane was that engine power was not seen sufficient for such tough plane, in ETO mostly. So here it is: P-40 with R-2600. Re-engined like LaGG-3 and Ki-61, the plane would have the power of 1600, 1750 and 1900 HP, for 1941, 1942 and 1944 respectively. 6 x .50 cal, clipped wings for some extra mph roll rate. Perhaps even adding a wing fillet as seen on P-38, to smooth those tick wing roots. Speed between 600 and 650 km/h - better than most of Russian, Italian or Japanese designs, while giving almost no advantage to Bf-109 Fw-190. 
The another change would be increase of fuel tank (aft pilot) to cater for increased consumption. 
Version with 1750 HP (1942), weighting 7000 lbs empty (650 more then P-40E) would have power loading of 0.25 hp/lb, compared with Fw-190A-8 with 0.245, Bf-109G-6 with 0.25. 
Wing loading 35 lb/ft, compared with Fw-190A-8 with 35.8, Bf-109G-6 with 34. So, as good as later German machines.
The '44 variant with 4 bladed prop (the visual difference vs. Twin wasp-engined P-36 is negligible - R-2600 was only 5% longer wider, but 80% heavier):


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## tomo pauk (Mar 20, 2010)

One of widely criticized planes on this board (from me too) was Fairey Firefly. 
Here is what it could look like with Napier Sabre. The 2200 HP version was feasible in 1943, offering performance comparable with FR.IV of 1945 (= around 620 km/h); the 3000 HP version (1945) with clipped wings probably around 680-700 km/h.


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## Colin1 (Mar 20, 2010)

Red cross for me Tomo
not sure how comfortable I'd feel over all those watery expanses with a Napier Sabre in front of me...

Anyone for engine failure during catapult launch?


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## tomo pauk (Mar 20, 2010)

What might child between force-landed La-5 and MS-406 from Finnish AF looked like - the real Morko Morane. Not unlike what happened to LaGG-3 when transformed to La-5.
With some 1500 HP and 2 x Shvak 20mm, and necessarry reinforcements, of course.


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## tomo pauk (Mar 20, 2010)

Colin1 said:


> Red cross for me Tomo
> not sure how comfortable I'd feel over all those watery expanses with a Napier Sabre in front of me...
> 
> Anyone for engine failure during catapult launch?



I was under impression that Napier Sabre had it's bugs sorted out by 2nd half of 1943 - Wiki says this in article about development of Sabre:


> In December 1942 the company was purchased by English Electric, who immediately ended the supercharger project and focused the entire company on the production problems. The situation quickly improved.


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## tomo pauk (Mar 20, 2010)

The Bf-109F-4 forced to land after being shot in wings and aft fuselage, so Soviets decided to give new life to the front part - hence the Yak-1 what-if, with some German hardware on board. Hopefully just under 650km/h - 400 mph - emulating the 109F-4 performance.


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## tomo pauk (Mar 21, 2010)

How it might've looked: Avia-135 from Bulgarian air force, with Twin Wasp from B-24 that crash landed. 1200 HP vs. 860 as in original, for comfortable 600 km/h, two MG-151/20 partly buried in wings.


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## Snautzer01 (Mar 21, 2010)

How about a B17 with a little help??


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## Snautzer01 (Mar 21, 2010)

or ho about a Messerspit


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## tomo pauk (Mar 21, 2010)

Neat pics


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## Snautzer01 (Mar 21, 2010)

We all know that the Me109 Z was on the drawing board. Little known is that Republic was going the same way


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## Snautzer01 (Mar 21, 2010)

In the beginning of 1944 it became clear that there had to be an early warning system againt the low flying russian attack planes, wich caused great losses to the Wehrmacht.

It had to have endurance given the enormous front that had to be protected. Because the Fieseler Fi156 was in quantity on the Ost front plans were made to equip these with a FuG 212.

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## Snautzer01 (Mar 21, 2010)

After encounters with the latest Allied fighters it became clear that the Messerspit was the superiour fighter on all fronts.
However the call for better cockpit view was noted.
Mid 1944 the first Messerstang as they were later to be become known left the assembly lines.


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## tomo pauk (Mar 21, 2010)

The fictional Fulmar III (1943) with Bristol Hercules VI (1650 HP) - hopefully enough to slung a torpedo, or to reach 480-500 km/h clean.


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## tomo pauk (Mar 21, 2010)

Hey, Snautzer, the thread is about re-engined planes (= planes with engines different than ones really mounted).


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## Snautzer01 (Mar 21, 2010)

Ahh i thought re engineered.


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## Snautzer01 (Mar 21, 2010)

Henschell Hs 129 with the engines it needed.

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## tomo pauk (Mar 21, 2010)

Yep, a mean looking bugger 
What engines (seems like DB-600) are those? The side view lacks the radiators, btw.


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## tomo pauk (Mar 21, 2010)

How might have looked Ki-61 with front end of an captured P-40 and clipped wings, HMGs relocated in wings. Perhaps 600-630 km/h - depending on Allison - and comparable with Hellcat Spit Mk.V.


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## tomo pauk (Mar 21, 2010)

The unarmed heavy bomber for RAF - Lanc with R-2800, turbocharged of course. Outpacing anything Germans were fielding.


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## tomo pauk (Mar 22, 2010)

What should be true 'schnellbomber': Ju-88, no guns, 1 crew member less, Argus engine (acting as supercharger for Jumos) between pilot's place and bomb bay. Perhaps emulating performance of real Do-217P in 1940?


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## Waynos (Mar 22, 2010)

As a schnellbomer, the Ju-88 prototype, which was a very different looking aircraft, was probably closer to what was later achieved with the Mosquito. This prototype with more power might perhaps work?


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## tomo pauk (Mar 22, 2010)

Yes, as I know RLM kept adding requirements (= weight and drag) eventually making it slower then it should've been. More HP would help it, but Germans had nothing 'classic' to offer. One of reasons I've added the Argus - the Jumos (ones with presssurized cooling system, available from 2nd half of 1940) would develop the full power even above 30 kft. Later replacing them with BMW 801 - those would rock


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## Colin1 (Mar 22, 2010)

What are the net benefits
of using a third powerplant to act as a supercharger for the two existing units?
I can't see the weight of even two supercharger assemblies approaching the weight of a powerplant and what effect will the third unit be having on fuel consumption/range?


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## tomo pauk (Mar 22, 2010)

How might have looked the Romanian 400mph + fighter: IAR-80 hull mated with engine salvaged from P-38J, along with four .05cals. Radiator copied from Hurricane. Supercharger between engine and windscreen. 
Empty weight circa 2000-2200 kg propelled by 1425 HP - the ultimate lightweight fighter.


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## tomo pauk (Mar 22, 2010)

Colin1 said:


> What are the net benefits
> of using a third powerplant to act as a supercharger for the two existing units?
> I can't see the weight of even two supercharger assemblies approaching the weight of a powerplant and what effect will the third unit be having on fuel consumption/range?



The plane with added and deleted stuff would be perhaps 300 kg heavier ( cca 3%) more then ready-to-go JU-88A-4. The main benefit is about power, though: the main engines does not need to drive the superchargers themselves - that's the job of 'slave' engine (Argus). The more fuel could've been carried above the Argus to remedy the consumption. With more power, plane would flew faster higher (nothing new), better utilising residual thrust for even more speed. 
The real plane using such arangement was Do-217P (one DB-605 as slave buried in hull, two DB-603 as masters), being way faster higher then Do-217Ms without DB-605 - despite added weight of DB-605 accesories.


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## tomo pauk (Mar 22, 2010)

Another underdog - He-112. 
Here is how those Romanians coul've used M-88 engine from captured Su-2 (1000-1200 HP, depending on who is talking) to make it go faster then Yak-1 stuff.


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## tomo pauk (Mar 22, 2010)

Yak-1 with engine salvaged from P-40 would perhaps looked this way. Two 20mm under wings. Speed perhaps 600-630 km/h depending on engine.


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## tomo pauk (Mar 23, 2010)

As promised on another thread, here is radial-engined Hurricane what-if.
Engines - R-2600 or Hercules, from 1500-1900 HP  The additional fuel tank behnid pilot, to cater for increased weight of new engine.
The 1st image is an ad-hoc modification, and 2nd one is more throughout, with bubble-canopy from Typhoon and with clipped wings for extra speed roll rate. Also the dorsal fillet for better stability, following the idea from Tempest P-47D for example.

Almost a Hayate, won't you say  Or Tempest II/Sea Fury.


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## tomo pauk (Mar 23, 2010)

The real bomber buster, or German P-38: the He-280 with DB-601/605. 'New' engines mounted slightly more out up for prop clearance. 2 x MK 108 instead of 3 x MG 151. Empty weight climbs from 3200 kg to cca 4700 since new powerplant is much heavier. Maybe the cannons would be mounted in wing roots to remedy the CoG changes. Wing loading is hefty (He-280 did have a small wing), but power loading is pretty good. Perhaps as fast as Mustang, but not as maneuverable.


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## tomo pauk (Mar 23, 2010)

How might have looked the Me-262 with some salvaged engines - depicted here with Merlins from Lancasters or Halifaxes. Perhaps as fast as P-82 with 1600 HP Merlins. Two MK-108 deleted from front, replaced with ones in gondolas from Bf-109 located to lower hull, behind wings because of CoG issues. 
The similar venture was possible with DB-601/605 to solve the problem of awesome airframe waiting for engines.


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## tomo pauk (Mar 24, 2010)

The tank-busting Defiant, with another engine:


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## tomo pauk (Mar 24, 2010)

How to turn Fairey Battle into a proper bomber - delete Merlin and add two radials. The more throughout modification would've included addition of turret from Defiant - 2nd pic. Ready to pounce those damn bridges over Albert canal 
The Australian Canadian production would've involved Twin Wasps instead of Taurus engines. With 2100-2400 HP vs. 4-4.5 tons empty it would beat many single-engined types.
Also as a night fighter it would've been pretty good.

One or two 40mm would've fitted in nicely, in place of bomb aimer.


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## Colin1 (Mar 24, 2010)

tomo pauk said:


> How might have looked the Me262 with some salvaged engines... ...Perhaps as fast as P-82 with 1600hp Merlins. Two MK-108s deleted from front, replaced with ones in gondolas


3-nacelle frontal cross-section, underwing gondolas; can't see it topping a P-82


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## tomo pauk (Mar 24, 2010)

On a benefit side, it had swept wing.


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## Shortround6 (Mar 24, 2010)

tomo pauk said:


> On a benefit side, it had swept wing.



On the debt side the engines from a bomber were single stage supercharged engines and developed their power

at lower altitude than the engines in a P-82. Lower altitude=thicker air=higher drag. 

Also I would be very careful about assessing performance based on nominal take-off HP ratings when max speeds were often obtained at much higher altitudes and in many cases using WEP ratings much higher than the nominal take-off rating.


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## tomo pauk (Mar 24, 2010)

Valid points 

edit: The Lancasters w/ Merlins have had service ceiling (with decent bomb load) of way above 20 000 ft, so 'my' 262 had merit too.


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## Shortround6 (Mar 24, 2010)

tomo pauk said:


> Valid points
> 
> edit: The Lancasters w/ Merlins have had service ceiling (with decent bomb load) of way above 20 000 ft, so 'my' 262 had merit too.



Service ceiling is usually the altitude at which the climb rate has dropped to 100ft per minute. 

Please note that the Merlins used in the bombers performed almost the same as the Merlins used in Hurricane II's and in P-40F's. Most of these engines were rated for 1420HP at 11,000ft in high gear. Power decreasing with altitude after that. 

Merlin 1650-7s, depending on what fuel they were feed were rated at 1625hp at 12,500ft (18lbs of boost) in high gear or 1860hp at 11,000ft (25lbs of boost) or 1580hp at 16,000ft (18lbs boost).

The -23/25 engine used in the P-82 was rated at 1500hp at 15700ft military power which is not WEP. 

Allison engines used in later P-82s gave 1250hp at 32,700ft.


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## hawkeye2an (Mar 25, 2010)

How about a Grumman F7F with DeHaviland Hornet engines? That beautiful slim,streamlined fuselage just asks for those engines. I am currently building one in 1/48th for our 'what if' contest for our local modeling club. The Hornet used "slimline" Rolls-Royce Merlin engines that were versions of the Merlin with engine ancillaries repositioned to achieve a minimum frontal area and less drag.


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## Waynos (Mar 25, 2010)

hawkeye2an said:


> How about a Grumman F7F with DeHaviland Hornet engines? That beautiful slim,streamlined fuselage just asks for those engines. I am currently building one in 1/48th for our 'what if' contest for our local modeling club. The Hornet used "slimline" Rolls-Royce Merlin engines that were versions of the Merlin with engine ancillaries repositioned to achieve a minimum frontal area and less drag.



That would, quite possibly, look even more beautiful than a Spitifre! In fact the description reminds of Supermarines own twin-Merlin proposals. Please post a picture here when its complete?


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## tomo pauk (Mar 25, 2010)

Replacing R-2800 with *anything* is blasphemy 

(steps from soap box)

It would've been a helluva plane.


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## hawkeye2an (Mar 25, 2010)

It's true. But I'm just going for BEAUTIFUL!


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## tomo pauk (Mar 25, 2010)

The what-if Skua III, or Roc  :
Merlin in front takes advantage of generous original front part of Skua, pilot's seat is moved to aft part of reduced, single-seat cockpit, the place previously occupied by piot his equipment is fuel tank (a-la F-4U). 8 x 0.303 in wings for the starter, radiators a-la Spitfire so the bombs could be carried under centreline if needed. Clipped wings.
Hopefully as good as Sea Hurricane, Wildcat, or (don't laugh, by late 1941 it would've had 1300 HP), A6M Zero.


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## tomo pauk (Mar 26, 2010)

A better looking version, late 1941/early 1942, 2-4 Hispano II in wings, Merlin with 1400 HP (1600 HP early 1943):


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## Colin1 (Mar 26, 2010)

tomo pauk said:


> On a benefit side, it had swept wing.


A recip will see no benefit from a swept wing and even if it was somehow fast enough, the sweep-back of the Me262 wing wouldn't have added much.


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## tomo pauk (Mar 26, 2010)

I disagree.


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## Waynos (Mar 27, 2010)

propeller drag.


love the skua. it was originally proposed with the Kestrel and looked similar to yours.


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## tomo pauk (Mar 27, 2010)

Too bad FAA didn't put more faith in it (or directed in a 'better' way) - with later Pegasus (1000+ HP), and/or new Taurus engines it would've doubled the bomb load to 1000 lb. Better than Aichi 'Val' and as good as most of Dauntleses ('till dash-5 perhaps).


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## Burmese Bandit (Mar 28, 2010)

Tomo, let me thank you on making this thread. This is one really good looking thread!!!

Now let's see...can you make a B-29 with 4 Napier Sabres in (a) tractor and (b) pusher configuration, a la the B-36? 

And if you could moung a slave Napier in the certral ring, losing the fuel there, of course, what kind of height/speed performance could we see? 

Without the slave, what kind of low-level Tokyo incendiary type bombing profile could we see?


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## Colin1 (Mar 28, 2010)

Burmese Bandit said:


> Now let's see...can you make a B-29 with 4 Napier Sabres in (a) tractor and (b) pusher configuration, a la the B-36?
> 
> And if you could moung a slave Napier in the certral ring, losing the fuel there, of course, what kind of height/speed performance could we see?
> 
> Without the slave, what kind of low-level Tokyo incendiary type bombing profile could we see?


You could
and you'd end up with a B-29 that couldn't fly as high as a B-17

See above.

Low-level bombing would be around the same as the R-3350-engined B-29 whilst being less resilient to ground fire in and around the engine nacelles.


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## tomo pauk (Mar 28, 2010)

Can make the pic, but I agree with Colin here


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## GrauGeist (Mar 28, 2010)

As far as the Me262's conversion goes, the wings were swept back to solve CoG issues, placing those engine nacelles that far forward would skew it's Center of Gravity substantially resulting in a serious nose-heavy condition.

If any piston engines would be considered, perhaps the BMW 801D-2 raised up in a cowling that bisects the wing?

I know the 801 was much heavier than the DB or Jumo, but it had advantages, too.


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## tomo pauk (Mar 28, 2010)

I've acknowledged that such (what-if) construction would have CoG issues, and proposed relocation of half of armament it's ammo from nose to behind wing gondolas


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## GrauGeist (Mar 28, 2010)

Granted, but the Mk108 was only 130 pounds each (not counting the ammo). Considering the Jumo weighs about 1,585 pounds and the DB weighs about 1,320, you do have a lighter conversion. But once those engines move ahead of the CoG, you'll have serious issues, even if you removed all the cannon and the foreward fuel cell to compensate.

Remember how sensitive the Me262 A-2a was when it released it's two nose-mounted bombs? Just that small of a change in the Center of Mass on the Me262's airframe had huge consequences.


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## Colin1 (Mar 28, 2010)

GrauGeist said:


> Remember how sensitive the Me262 A-2a was when it released it's two nose-mounted bombs? Just that small of a change in the Center of Mass on the Me262's airframe had huge consequences.


To be fair GG
2 x SC250s, roughly 1,000lbs, dropped from one extreme end or the other (the nose in this case) doesn't require a particularly sensitive aircraft in order for it to get upset about the sudden change in trim.


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## tomo pauk (Mar 28, 2010)

GrauGeist said:


> Granted, but the Mk108 was only 130 pounds each (not counting the ammo). Considering the Jumo weighs about 1,585 pounds and the DB weighs about 1,320, you do have a lighter conversion. But once those engines move ahead of the CoG, you'll have serious issues, even if you removed all the cannon and the foreward fuel cell to compensate.
> ...


The CoG is affected by torque - certain weight multiplied by it's distance from CoG. Eg. torque of a 600 kg added piece, 1 meter away from CoG can be canceled out with an opposite 200 kg piece, 3m away from CoG. Or, by removing of the 150 kg piece 4m away from CoG, on the same side of CoG where we just added those 600kg.
Any other combination works. (Sorry if I sound boring).
That was my idea - to cancel effects of adding something heavy, but closer to CoG, by deleting something light, but placed away from CoG, and adding the same deleted stuff on the opposite side of CoG.


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## Shortround6 (Mar 28, 2010)

It is not just the weight of the engines but the weight of the powerplant. 

Where are the propellers (at well over 300lbs each) in relation to the CG?
The radiators and oil coolers in the "Chin" position in regards to the CG?
weight of the cowlings,etc?


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## tomo pauk (Mar 29, 2010)

Under the 'heavy piece' I was referring to the whole powerplant. That's why my sentence starts with "Eg." when talking about torque.


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## tomo pauk (Mar 29, 2010)

Anyway, here is how might have looked one venerable bird that received a little help - perhaps via Twin Wasp, or Taurus: re-engined Swordfish. 
The engine mount received some streamlining. Now, how about the carrier wing (2nd half of 1940) with 30% of such Swordfishes, 40% of Merlin-engined Skuas (2-seat multi-role) 30% of dedicated fighter Skuas (as already depicted in this thread)


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## tomo pauk (Mar 29, 2010)

The 'proper' Stuka' version that never existed, with BMW-801 and 13,1mm MG in barbete (from Me-410):

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## tomo pauk (Mar 29, 2010)

If Fairey can do it, so can Junkers: Stuka with 2 engines. BMW or Bramo, retractable U/C, much easier instalation of tank-busting cannon(s), while it could still hurl a big bomb if no heavy cannon is present. 
2nd pic lacks wing engine to show 37mm cannon mounting. An all-around ground attack plane, with perhaps 1-2 30mm cannons, more up forward, or in wing roots, would of course enable the big bomb all the time. Stern barbete (not shown here) would be nice to have.


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## tomo pauk (Mar 29, 2010)

Another 'Schnellbomber', this time in Do-17 guise.
Instead of glass-house cockpit, the plane would've had the more streamlined, like one at 1st series of original. No gun armament, nor dedicated gunner. Instead of that, we have trusty Argus 410 to supercharge the main engines, located at where gunner was once. 

The second pic is a Mosquito-wannabe. The DB-601/605 are installed (as they really were in some Do-17 variants), Argus 411 is now behind bomb bay, slightly down for better air flow for cooling, 2-3 x 20-30mm, plus 1 x 20-30mm as 'schraege musik'. 
For expected performance, H. Nowarra claims that night fighter Do-17 with 2 x 1175 HP was good for 500 km/h in late 1941 (comparing favorably with Ju-88 Bf-110 in same role, prior 1944) so this combo ought to be really fast with 2 x 1350, or 2 x 1450 HP, with slave engine freeing up the power prior robbed by superchargers of main engines.


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## Waynos (Mar 30, 2010)

Hey Tomo, ever wondered about a radial Mossie? Although a quite different aircraft in reality, in this view at least the similarity of the IAe 24 Calquin is striking.


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## Colin1 (Mar 30, 2010)

I'd like a Griffon-engined Mosquito
with the glasshouse of a Dinah


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## tomo pauk (Mar 30, 2010)

I'll be home the day after tomorrow, so just a little patience


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## Markus (Mar 30, 2010)

tomo pauk said:


> The defender of free world - P-40.
> The most criticized part of plane was that engine power was not seen sufficient for such tough plane, in ETO mostly. So here it is: P-40 with R-2600.



Talk about lost opportunities.


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## Colin1 (Mar 30, 2010)

tomo pauk said:


> I'll be home the day after tomorrow, so just a little patience


I need it by Friday
don't you know there's a war on?


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## tomo pauk (Mar 31, 2010)

Always those demands from Air ministry 

Here is an up-engined Mossie, the engines are Sabres  for almost 4500 HP in 1943. Radiators removed to end of nacelle to cater for upped frontal weights. The new fuel cells in place of where once were radiators.


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## zoomar (Mar 31, 2010)

tomo pauk said:


> If Fairey can do it, so can Junkers: Stuka with 2 engines. BMW or Bramo, retractable U/C, much easier instalation of tank-busting cannon(s), while it could still hurl a big bomb if no heavy cannon is present.
> 2nd pic lacks wing engine to show 37mm cannon mounting. An all-around ground attack plane, with perhaps 1-2 30mm cannons, more up forward, or in wing roots, would of course enable the big bomb all the time. Stern barbete (not shown here) would be nice to have.



Now that is an incredibly cool looking airplane!!


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## tomo pauk (Mar 31, 2010)

Markus said:


> Talk about lost opportunities.



Strangely enough, although R-2600 was the most powerful (reliable available that is) aircraft engine 'till R-2800* come to play, it never served in a fighter aircraft. It was way more powerful than contemporary DB-601/605/603, Jumos, Merlins, BMW 801 prior 1945. Not to mention Soviet Japanese designs.

*Napier Sabre was contender with bugs solved in mid/late 1943


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## Shortround6 (Mar 31, 2010)

It had two things against it as a fighter engine. 

1. it's diameter, it was as big as an R-3350 which didn't do much for streamlining in the early days, bigger than an R-2800.

2. Wright never seemed to get a good high altitude supercharger. While take-off and low altitude power seemed to be fine even the 2 speed supercharged engines had critical (full throttle) altitudes of around 11,000-14,000ft which for western use was a bit on the low side. Not much better than an Allison. Combine that with the fact that there was no WER rating or that military power at 11,000-14,000ft was several hundred HP below the take-off rating and it just didn't offer the performance fighter designers were looking for. Great at getting heavy twin engined planes off the ground though.


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## tomo pauk (Mar 31, 2010)

The über-Mosquito - with two turbo-charged R-2800 
Turbos are at the end of nacelle.The late-1945 variant would've boast with 5600 HP on board.


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## zoomar (Mar 31, 2010)

tomo pauk said:


> Another underdog - He-112.
> Here is how those Romanians coul've used M-88 engine from captured Su-2 (1000-1200 HP, depending on who is talking) to make it go faster then Yak-1 stuff.



Well, here's what the Hungarians did try, the Weiss-Manfred WM-23, a He-112 variant with a Gnome-Rhone radial:


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## tomo pauk (Mar 31, 2010)

Shortround6 said:


> It had two things against it as a fighter engine.
> 
> 1. it's diameter, it was as big as an R-3350 which didn't do much for streamlining in the early days, bigger than an R-2800.
> 
> 2. Wright never seemed to get a good high altitude supercharger. While take-off and low altitude power seemed to be fine even the 2 speed supercharged engines had critical (full throttle) altitudes of around 11,000-14,000ft which for western use was a bit on the low side. Not much better than an Allison. Combine that with the fact that there was no WER rating or that military power at 11,000-14,000ft was several hundred HP below the take-off rating and it just didn't offer the performance fighter designers were looking for. Great at getting heavy twin engined planes off the ground though.



1: The diameter was only 5% greater than of Twin Wasps, the wide-spread fighter engine, says Wiki. The diameter was 4% greater than of R-2800, so not a great issue. If we look at A-20 B-25 cowlings, those were surely well streamlined. 

2. Wright was never tasked with such thing (hi-alt hi-performance). R-2800 (mech-supercharged) also took time to develop a supercharger set for 20kft +.


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## tomo pauk (Mar 31, 2010)

zoomar said:


> Well, here's what the Hungarians did try, the Weiss-Manfred WM-23, a He-112 variant with a Gnome-Rhone radial:



Wow, at 1st glance I thought it was F-4U  
Neat looking plane.


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## Shortround6 (Mar 31, 2010)

tomo pauk said:


> 1: The diameter was only 5% greater than of Twin Wasps, the wide-spread fighter engine, says Wiki. The diameter was 4% greater than of R-2800, so not a great issue. If we look at A-20 B-25 cowlings, those were surely well streamlined.



Please do the math. Twin Wasp is 48.1in in diameter, R-2600 is 54-55in in diameter. 6in is more than 5% of 48in. 

Frontal areas are given as 12.6 sq.ft for the twin wasp, 16.1 sq ft for the R-2600 and 14.8 sq ft for the 52.2 in dia R-2800. 

At 105.6hp/sq ft for the the R-2600 vs 135.1 hp/sq ft for the R-2800 isn't to hard to figure out why the fighter designers skipped the R-2600. HP is 1700 for the R-2600 and 2000 for the R-2800. 

The cowlings on the A-20 and B-25 were well streamlined but nowhere near as good as the cowlings on the FW 190 and the LA-5 through 9 series than used fan cooling. A feature that helped keep down the overall size of the cowlings on those planes. 




tomo pauk said:


> 2. Wright was never tasked with such thing. R-2800 (mech-supercharged) also took time to develop a supercharger set for 20kft +.



That is true but it sure doesn't change the fact that the Wright engine never had one while the P&W R-2800 was in production with such a supercharger by mid/late 1942.

The Wright engine was a very good engine that powered a lot of very good and very useful aircraft. It just wasn't a good choice for a fighter engine given what else was available.

Allison engines being good for 1400-1500hp at altitudes of 5,000ft or so when running at WEP in late 1942 or early 1943.


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## tomo pauk (Mar 31, 2010)

Yep, you're right about the difference vs. Twin Wasp - my bad.

I'm not pitting R-2600 vs. R-2800 in performance category - no point in that. 
But if we talk about availability date, R-2600 beats the 2800. That was my point all the way. Planes powered by 2600 were in combat 2 years before the ones with 2800 - not a bad thing for WW2 needs.

As for cowlings - esp. the one at A-20 looks really neat to me. I guess fan-cowling was no rocket science to prevent installation in an US fighter.



> Allison engines being good for 1400-1500hp at altitudes of 5,000ft or so when running at WEP in late 1942 or early 1943.


Two quirks there:
-5kft makes pretty low altitude, 1.7 km perhaps. 
-It's WEP rating for Allison. I doubt that WEP was out of capability of Wright to develop it by 1942 if brass asked for it in time German tanks overran Poland or France.


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## Shortround6 (Mar 31, 2010)

tomo pauk said:


> . Planes powered by 2600 were in combat 2 years before the ones with 2800 - not a bad thing for WW2 needs.



What planes powered by R-2600s were in combat in the summer of 1940?


tomo pauk said:


> As for cowlings - esp. the one at A-20 looks really neat to me. I guess fan-cowling was no rocket science to prevent installation in an US fighter.



The fan cowlings weren't rocket science but nobody used them until the FW 190 showed the way. Early attempts at streamline cowlings on the P-42 and P-48/66 didn't work out so well. 



tomo pauk said:


> Two quirks there:
> -5kft makes pretty low altitude, 1.7 km perhaps.
> -It's WEP rating for Allison. I doubt that WEP was out of capability of Wright to develop it by 1942 if brass asked for it in time German tanks overran Poland or France.



Liquied cooled engines worked better at WEP. You had to overload the cooling system which took a few minutes compared to overheating the aircooled engine. 
A GR2600-A5A engine from a 1941 book was credited at 1600hp for take off at 2400rpm. 1600hp/2400rpm at 1500ft low blower military power and 1400hp/2400rpm/11,500ft high blower military power. 
Radial engines didn't take to over revving as well as V-12s did either. 
WEP was usually obtained at below the rated altitude of the engine by fulling opening the throttle rather than restricting it's opening in order to limit power and save the engine.

Quirks are that a standard P-40E could develop close to 1500hp at low altitude for a couple of minutes instead of the 1150hp take off rating which evens things up a bit compared to a R-2600 which while rated for take-off at 1600-1700hp wasn't rated any higher. And at altitude the P-40E was still good for 1150hp at 11,000ft compared to the R-2600s 1400-1500hp at 11,000-14,000ft. 
The R-2600 does have more power but not as much as a comparison of the take-off ratings suggests. 

If you can find a rating for WEP for a R-2600 I would be interesting in seeing it.


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## Waynos (Mar 31, 2010)

Hmm, stupid idea coming.........pure fantasy of course...........Jet powered versions of the allied heavies, akin to the post war testbeds, but all-jet for 1945 deployment (4/6 Derwents/Goblins?)

High altitude turretless Lancaster for 500mph at 40,000ft?


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## Colin1 (Mar 31, 2010)

Waynos said:


> High altitude turretless Lancaster for 500mph at 40,000ft?


In 1945
could we hit anything from 40,000ft?


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## Waynos (Mar 31, 2010)

The ground


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## Colin1 (Mar 31, 2010)

Waynos said:


> The ground


Now
if we could just get the enemy to build his factories on the ground...


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## Colin1 (Apr 1, 2010)

Shortround6 said:


> If you can find a rating for WEP for an R-2600 I would be interesting in seeing it


I doubt you'll find one, the R-2600 was never fitted to fighters


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## tomo pauk (Apr 1, 2010)

Shortround6 said:


> What planes powered by R-2600s were in combat in the summer of 1940?



Okay, than it's 20 months vs. 24 as I've claimed. Still plenty of time - much less divides Fw-190 from Battle of Britain, or BMW-801 TS-series from 1944 combined bombing offensive, F4-U from Midway etc. 



> The fan cowlings weren't rocket science but nobody used them until the FW 190 showed the way. Early attempts at streamline cowlings on the P-42 and P-48/66 didn't work out so well.



Fw-190 badly needed the fan to provide useful level of reliability for it's engine - while still not beating R-2600 in power/availability/reliability combo for 3/4s of it's operational use (3 years that is).



> Liquied cooled engines worked better at WEP. You had to overload the cooling system which took a few minutes compared to overheating the aircooled engine.


Again, perhaps in theory. The Russian Ash-82FN had 'forsage' option to bolster the power output for short period of time - WEP in Russian that is.



> A GR2600-A5A engine from a 1941 book was credited at 1600hp for take off at 2400rpm. 1600hp/2400rpm at 1500ft low blower military power and 1400hp/2400rpm/11,500ft high blower military power.



In other words, it took 2 years, plus WEP for Allison to _almost_ equals the performance of R-2600 of 1940/41? I rest my case 



> Radial engines didn't take to over revving as well as V-12s did either.
> WEP was usually obtained at below the rated altitude of the engine by fulling opening the throttle rather than restricting it's opening in order to limit power and save the engine.



Okay - again it theory.



> Quirks are that a standard P-40E could develop close to 1500hp at low altitude for a couple of minutes instead of the 1150hp take off rating which evens things up a bit compared to a R-2600 which while rated for take-off at 1600-1700hp wasn't rated any higher. And at altitude the P-40E was still good for 1150hp at 11,000ft compared to the R-2600s 1400-1500hp at 11,000-14,000ft.
> The R-2600 does have more power but not as much as a comparison of the take-off ratings suggests.


That's still 250-350 HP more, 2 years before. 
Clear advantage in my eyes - I bet Germans would've ritually sacrifice ms. Eva Braun for availability of a reliable 1500 HP engine for Bf-109s in time of BoB. USA was the only country that had that option available, and they skipped it.



> If you can find a rating for WEP for a R-2600 I would be interesting in seeing it.



Colin covered that 

Actually, I've spent a lot of time searching for power curves of piston engines, but those are as rare as hen's teeth. I'd love to lay my hands on any of it


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## Shortround6 (Apr 1, 2010)

tomo pauk said:


> In other words, it took 2 years, plus WEP for Allison to _almost_ equals the performance of R-2600 of 1940/41? I rest my case



Except that the Allison was several hundred pounds lighter, including the radiator, and had about 1/3 the frontal area. 


tomo pauk said:


> Clear advantage in my eyes - I bet Germans would've ritually sacrifice ms. Eva Braun for availability of a reliable 1500 HP engine for Bf-109s in time of BoB. USA was the only country that had that option available, and they skipped it.



I am sure the Germans would have too. They might have even done it for a good 1500hp bomber engine. The Problem is that the R-2600 as built wouldn't have done much for the altitude performance of the 109. 
The diameter of an bare R-2600 is several inches greater than the outside diameter of the cowling of the BMW 801. It is around 600lbs heavier than an early Merlin or an Allison or a DB 601 so even factoring in the weight of radiator and coolant it is around 300lbs heavier. Then you need a heavier propeller and a larger oil tank/oil cooler. 
With-out a larger heavier/better supercharger the power of the R-2600 falls off at a lower altitude than the Merlin or DB 601 so performance at 20,000ft is much closer than the take of figures show. An R-2600 that developed 1700hp for take off was using 44.5in of boost or 1.48 atmo of pressure. it was also using low gear in it's supercharger which took about half the power of high gear to drive. 

The US may have had reason to skip the option.


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## tomo pauk (Apr 1, 2010)

Shortround6 said:


> Except that the Allison was several hundred pounds lighter, including the radiator, and had about 1/3 the frontal area.



Did you include radiator for comparison of frontal areas?
Other planes were re-engind with heavier more draggier engines (also, more powerful) and were better than original ones. And the 1st P-40s had 2 hull MGs, wich would've been not installed (but installed in wings), so the weight increase would be channeled through greater firepower.
When talking about added weights, we need to look at whole plane, not the engine itself, which I've included in my post, BTW, along with wing area reduced to 300 ft^2:



tomo pauk said:


> Version with 1750 HP (1942), weighting 7000 lbs empty (650 more then P-40E) would have power loading of 0.25 hp/lb, compared with Fw-190A-8 with 0.245, Bf-109G-6 with 0.25.
> Wing loading 35 lb/ft, compared with Fw-190A-8 with 35.8, Bf-109G-6 with 34. So, as good as later German machines.





Shortround6 said:


> I am sure the Germans would have too. They might have even done it for a good 1500hp bomber engine. The Problem is that the R-2600 as built wouldn't have done much for the altitude performance of the 109.
> The diameter of an bare R-2600 is several inches greater than the outside diameter of the cowling of the BMW 801. It is around 600lbs heavier than an early Merlin or an Allison or a DB 601 so even factoring in the weight of radiator and coolant it is around 300lbs heavier. Then you need a heavier propeller and a larger oil tank/oil cooler.
> With-out a larger heavier/better supercharger the power of the R-2600 falls off at a lower altitude than the Merlin or DB 601 so performance at 20,000ft is much closer than the take of figures show. An R-2600 that developed 1700hp for take off was using 44.5in of boost or 1.48 atmo of pressure. it was also using low gear in it's supercharger which took about half the power of high gear to drive.



We can take our comparison three-way perhaps (skipping the turbo-supercharged versions for now):
1. vs. Merlin (hi-alt) DB-601/605 - while I agree that those might better choice for hi-alt job, they were not the option for USAAC in 1940-1943 period 
2. vs. Allison, BMW-801, Klimov-105, AM series, Ash-82 series, Merlin (low-alt), plethora of Japanese engines - when R-2600 have had advantage in at least 2 of 3 categories (power, reliability, availability) 
3. vs. Sabre, R-2800, Griffon - r-2600 was available far earlier that each of those



> The US may have had reason to skip the option.



Italians loved biplanes and loathed inline engines, Germans thought the war ended after they conquered France, Brist thought 2pdr is enough armament for a 40 ton tank, Japanese adored turn'n'burn, and don't get me started about Russkies

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## tomo pauk (Apr 1, 2010)

A more streamlined version of radial-engined Mossie:


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## Shortround6 (Apr 1, 2010)

tomo pauk said:


> Did you include radiator for comparison of frontal areas?


I seriously doubt the radiator was 2 twice the size of the engine.


tomo pauk said:


> Other planes were re-engind with heavier more draggier engines (also, more powerful) and were better than original ones.


True but sometimes it is a question of how much more powerful and at what altitudes. In addition sometimes the new engine was more reliable than the old engine and was desirable from that stand point alone. The Earlier 1600hp R-2600s when equipped with a two speed supercharger were rated at a military power of 1400hp at 11,500ft. If I have done the math correctly this means they should have been good for about 1100hp at 18,000ft. Please compare that with Early Merlins, DB 601s, etc. When comparing to the Russian aircraft please note that at least one source credits an early version of the Ash-82 with 1330hp at 17,716ft. 

Maybe your super P-40 would be better than an Allison version, the question is by how much. If the improvement is minor it may not be worth the trouble.



tomo pauk said:


> And the 1st P-40s had 2 hull MGs, wich would've been not installed (but installed in wings), so the weight increase would be channeled through greater firepower.
> When talking about added weights, we need to look at whole plane, not the engine itself, which I've included in my post, BTW, along with wing area reduced to 300 ft^2:



You have lost me on this section. I was referring just to the weight of the engine installation. moving the guns from the fuselage to the wing may help with the balance but does nothing for power plant comparisons. Using power to weight ratios for empty aircraft seems a little bogus when trying to estimate performance. For trying to estimate performance vrs other aircraft you might what to try the power to weight in flying condition at combat altitude. A normal P-40E is around 7850lbs in such condition (allowing for burning off about 50% of fuel). Figuring your R-2600 powered plane at at least 8000lbs in such a condition ( even allowing for reduced armament of 4 guns) means a power to weight ratio of about .1375hp per pound at 18,000ft. Want to re-figure the German planes?






tomo pauk said:


> We can take our comparison three-way perhaps (skipping the turbo-supercharged versions for now):
> 1. vs. Merlin (hi-alt) DB-601/605 - while I agree that those might better choice for hi-alt job, they were not the option for USAAC in 1940-1943 period
> 2. vs. Allison, BMW-801, Klimov-105, AM series, Ash-82 series, Merlin (low-alt), plethora of Japanese engines - when R-2600 have had advantage in at least 2 of 3 categories (power, reliability, availability)
> 3. vs. Sabre, R-2800, Griffon - r-2600 was available far earlier that each of those



You lost me again, what turbo charged versions of which engine were we discussing? the P-38s Allison?
for the rest;
1. True but the idea is try and beat them. if the combination won't do the job why bother? Allison did offer an engine with 9.60 supercharger gears fairly early but it had trouble with the gear sets. When finally used the 9.60 gears sets gave 1125hp at 15,500ft. Not 18,000ft but a much easier "what if".
The Merlin engine used in the P-40F was good for 1120hp at 18,500ft. This seems to have been an option for the USAAC in 1942 and 1943. Since we know how it turned out I am just not seeming the utility of a heavier, draggier version of the plane with little more power at altitude performing a whole lot better. 
2. The BMW-801 and the Ash-82 aren't really common in the time period under discussion are they? at least not until the very end. And again if the question is even power available at 18-20,000ft the R-2600 is questionable.
3. Mixing time lines a bit. No question the R-2600 is ahead of the Sabre and the Griffon but it is not that far ahead of the R-2800. In order to ensure your availability of engines factory construction and tooling up have to begin about 1 1/2 to 2 years before the planes go into combat in numbers. What do you know? The US was planning on massive factory construction projects for the R-2800 in the end of summer/fall of 1940.


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## tomo pauk (Apr 1, 2010)

I'll be back tomorrow for a more throughout answer 

Now the most streamlining one can do for radial engine, other perhaps to bury it on airframe: P-40 with elongated prop shaft ducted fan, here with 1900 HP.


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## tomo pauk (Apr 2, 2010)

Shortround6 said:


> I seriously doubt the radiator was 2 twice the size of the engine.


Never said it was However, when comparing inline vs. radial, we need to take it into account. So there is no 3:1 ratio of frontal crosses, but perhaps 3:2 for P-40 case.



> True but sometimes it is a question of how much more powerful and at what altitudes. In addition sometimes the new engine was more reliable than the old engine and was desirable from that stand point alone. The Earlier 1600hp R-2600s when equipped with a two speed supercharger were rated at a military power of 1400hp at 11,500ft. If I have done the math correctly this means they should have been good for about 1100hp at 18,000ft. Please compare that with Early Merlins, DB 601s, etc. When comparing to the Russian aircraft please note that at least one source credits an early version of the Ash-82 with 1330hp at 17,716ft.



1100hp @ 18kft (military rating) was awesome figure for a reliable engine in production in 1940 - Allisons for P-40 were capable for that in 1943. And almost as good as Merlin XX (1100 @ 22kft, but only 1300 for take off).
As for DB-601, I'll bet that it took germans to develop 601E (one for Bf-109F4, in 1941) to better those figures.

Thanks for pointing out my mistake about Ash-82. Guess Russkies were right to re-engine the LaGG-3 into something that would combat Germans on more level terms - as I advocate so far for Americans 

About 'etc.' ones, those don't come any near the top-notch engines of 1940.



> Maybe your super P-40 would be better than an Allison version, the question is by how much. If the improvement is minor it may not be worth the trouble.



My estimates were that 1940/41 variant (1600 HP, 4 x .50in, wing area down to 200 ft^2, empty weight under 7000 lbs) would be vastly better than any Japanese, Russian or Italian design, better than Spit II Bf-109E, and as good as Bf-109F2 Spit V. Better than any other contemporary US plane, of course
The mid 1942 variant (1750 HP, 4-6 .50in) would've been second only to Spit IX P-38F when at high altitudes (one plane not available for USAAF in more than token numbers, other twice as expensive); as good as Fw-190A-3, better than anything else. 
By mid 1943 plethora of (nominally) better planes are available for waring parties, but P-40 has served it's purpose - to hold the enemy until those come to play.



> You have lost me on this section. I was referring just to the weight of the engine installation. moving the guns from the fuselage to the wing may help with the balance but does nothing for power plant comparisons. Using power to weight ratios for empty aircraft seems a little bogus when trying to estimate performance. For trying to estimate performance vrs other aircraft you might what to try the power to weight in flying condition at combat altitude. A normal P-40E is around 7850lbs in such condition (allowing for burning off about 50% of fuel). Figuring your R-2600 powered plane at at least 8000lbs in such a condition ( even allowing for reduced armament of 4 guns) means a power to weight ratio of about .1375hp per pound at 18,000ft. Want to re-figure the German planes?



My intention was to show how the increased frontal weight influence at CoG would've been canceled 
I don't think it's bogus comparing empty weights, since one loaded weight might differ from another loaded weight (for same plane) for different tasks. 
We can do what you propose, but, for re-figuring the German planes, I do lack accurate figures for their power output @ 18kft.



> You lost me again, what turbo charged versions of which engine were we discussing? the P-38s Allison?



We are not, so I've made a disclaimer 



> for the rest;
> 1. True but the idea is try and beat them. if the combination won't do the job why bother? Allison did offer an engine with 9.60 supercharger gears fairly early but it had trouble with the gear sets. When finally used the 9.60 gears sets gave 1125hp at 15,500ft. Not 18,000ft but a much easier "what if".



Yep, but those 1125 are:
-achieved at WEP rating - so 5-min setting, 
-in late 1942
[email protected] 2500 ft less (minor issue, but still)



> The Merlin engine used in the P-40F was good for 1120hp at 18,500ft. This seems to have been an option for the USAAC in 1942 and 1943. Since we know how it turned out I am just not seeming the utility of a heavier, draggier version of the plane with little more power at altitude performing a whole lot better.


1942/43 minus 1940 equals half of length of US WW2. That is the main advantage of 'my' P-40. 



> 2. The BMW-801 and the Ash-82 aren't really common in the time period under discussion are they? at least not until the very end. And again if the question is even power available at 18-20,000ft the R-2600 is questionable.



1600 HP engine was major breakthrough for Germans in late 1941/early 1942 - that is when those HP were relaible, while never being available in numbers needed. 
R-2600 offered the same power in 1940, reliable, available. By 1942 it was 1750 HP.



> 3. Mixing time lines a bit. No question the R-2600 is ahead of the Sabre and the Griffon but it is not that far ahead of the R-2800. In order to ensure your availability of engines factory construction and tooling up have to begin about 1 1/2 to 2 years before the planes go into combat in numbers. What do you know? The US was planning on massive factory construction projects for the R-2800 in the end of summer/fall of 1940.


No mixing here - the group 3 were engines with more HP than R-2600, but with a major shortcoming: not available.


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## tomo pauk (Apr 2, 2010)

Focke Wulf proposed their Fw-189 for a competition eventually won by Hs-129. 
Here is how it might've looked the 189 with some HP it really needed. The tail gunner is present - feature Hs-129 lacked all the time. Both crew members are within armor.

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## hawkeye2an (Apr 2, 2010)

tomo pauk said:


> Focke Wulf proposed their Fw-189 for a competition eventually won by Hs-129.
> Here is how it might've looked the 189 with some HP it really needed. The tail gunner is present - feature Hs-129 lacked all the time. Both crew members are within armor.



Unusual looking bird. Could we see a top view?


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## tomo pauk (Apr 2, 2010)

Ugly, perhaps 

Not-that-representative picture, but here it goes:

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## Burmese Bandit (Apr 2, 2010)

Tomo, here is an idea I have had for some time for a really, really fast and long range Mossie Recce Photo plane:

Take a Sabre and put it at the front. Take two DH Gipsy Twelve engines and mount them in pusher configuration, so that not only do they produce less drag, the propellers in pusher produce more thrust and their weight helps to counterbalance the very heavy Sabre in front. 

Also have a third Gipsy as a slave engine driving a supercharger in the body. This will give an extra 200 hp to the Sabre and an extra 50 each to the wing Gipsies. 

Total, at least 3,300 to 3,500 hp in all. 

Performance at least 450 - 460 mph. Very very long range possible if Central Sabre is shut down.


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## tomo pauk (Apr 2, 2010)

(Really had to re-think about this claim, sorry for being boring)


Shortround6 said:


> The Merlin engine used in the P-40F was good for 1120hp at 18,500ft. This seems to have been an option for the USAAC in 1942 and 1943. Since we know how it turned out I am just not seeming the utility of a heavier, draggier version of the plane with little more power at altitude performing a whole lot better.



By second half of 1942, R-2600 received 10% more power than the plain 1600 HP version, which should interpolate to 1200 HP @ 18kft, military power. In same time the Merlin XX from P-40F was able to do perhaps 1000 HP @ same alt, military power. 
So, 20% more power, for 1-6% increase of weight* (weight difference between complete power-packs was perhaps 400 lbs, almost canceled out by reducing armament ammo to 4 HMGs related ammo). The drag increase (related to bulkier engine) would present the issue, but I've already proposed clipped wings to cut the drag there.

* so not the 7000 lbs empty as I've proposed previously, but 6500 for 4 HMG version.


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## Shortround6 (Apr 2, 2010)

tomo pauk said:


> (Really had to re-think about this claim, sorry for being boring)
> 
> 
> By second half of 1942, R-2600 received 10% more power than the plain 1600 HP version, which should interpolate to 1200 HP @ 18kft, military power. In same time the Merlin XX from P-40F was able to do perhaps 1000 HP @ same alt, military power.
> ...



UH, NO. the R-2600 went from 1600hp to 1700hp not 1750hp. not a 10% increase. It was good for 1450Hp at 14,100ft though. Figuring the difference in air pressure between 14,000ft and 18,500ft the R-2600 should be good for around 1207hp at 18,500ft. I have already told you the Merlin was good for 1120hp at this altitude which was in the section you quoted. Why you knocked it down another 120 hp I have know idea. Difference is less than 10% not 20%. I doubt clipping the wings a bit is going to cancel out the size the the R-2600. 

P40Fs were a bit heavier than the E model at just under 7100lbs empty. loosing 180lbs worth of guns doesn't change things much. 

For comparison one source for the FW 190A-3 gives an empty weight of 6393lbs with an empty equipped (with guns, radio etc) weight of 7,110lbs and a loaded weight of 8,770lbs. Adjust loaded weight for fuel burned off before combat. Unfortunately for ANY P-40s chances of success the FW 109A-3's engine, while rated at 1700hp for take-off was rated at 1440hp at 18,700ft. giving about a 19% advantage over even your super P-40 not counting the lower drag installation of the FW 190. 

Figures I have for the Bf 109F-4 give 1350Hp for take-off but 1300hp at 18,045 ft. this is for a 6400lb plane loaded. 

Another thing to note is that the R-2600 can suck down 215 gallons an hour at the 1700hp rating. Or roughly 50% more fuel per minute than an Allison engine, Granted that while cruising the consumption should be somewhat closer but any engine swap might have to consider larger fuel tanks or rather shorter range.


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## tomo pauk (Apr 3, 2010)

Yep, it was 1700 HP in 1942, you're right.



> I have already told you the Merlin was good for 1120hp at this altitude which was in the section you quoted. Why you knocked it down another 120 hp I have know idea.



It was WEP figure, so I cut 10% to get military rating. It's 20% difference with R-2600, military rating.



> P40Fs were a bit heavier than the E model at just under 7100lbs empty. loosing 180lbs worth of guns doesn't change things much.



Perhaps you mean 'loaded' when stating 7100 lbs figure for P-40F? 



> For comparison one source for the FW 190A-3 gives an empty weight of 6393lbs with an empty equipped (with guns, radio etc) weight of 7,110lbs and a loaded weight of 8,770lbs.



The empty weight that does not include guns radio is pretty vague number; the 7110 lbs figure makes sense when comparing empty weights. That figure would be equal to 'my' P-40 with 6 guns.



> Another thing to note is that the R-2600 can suck down 215 gallons an hour at the 1700hp rating. Or roughly 50% more fuel per minute than an Allison engine, Granted that while cruising the consumption should be somewhat closer but any engine swap might have to consider larger fuel tanks or rather shorter range.



The historical P-40 has had much greater range than Spit or Bf-109 (Wiki says as greater as 'double'), so the minor decrease wouldn't be that detrimental.


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## tomo pauk (Apr 3, 2010)

The Navy use of such P-40 might have a clue... Alternate time line:

-1st aug 1940: after hearing of production of Army plane capable of 375 mph, Navy performs comparison against F2A F4F. 'P-40' soundly defeats the fixed-wing examples of those, so Navy orders a navalized version as a stop gap 'till F4U comes. Main shortcoming is low set pilot's seat.
-1st dec 1940: the F12C, navalized 'P-40' is flown. Wing folds like at SB2C, wing area reversed back to 236 ft, pilot seat raised 1/2 feet, arrester hook. 600 lbs heavier and 10 mph slower then 'P-40' with same gear engine.
-1st june 1941: Curtiss starts production of F-12C 
-1st oct 1940: General Motors starts production of FC12 as FM1
-1st dec 1941: 1st carrier wings declared operational with new plane. 
(7th dec 1941: Army 'P-40' make IJN take 25% greater losses, while USN loses one BB less. 'P-40s' land with many bullet holes from friendly fire
-may 1942: (Battle of Coral Sea) Lexington CV receives only 1 torpedo hit and makes it to Pearl. Yorktown CV receives only a half of historical bomb hits because of action of their FC12As (with 1700 HP, capable for 375-380 mph)
(-1942: due to plentiful Martlets, RN suffers half of historical casualties on Malta convoys)
-june 1942: (Battle of Midway) four USN carriers sink four IJN carriers for no losses
-july 1942: Navy cancels SB2C project, instead orders the TBF with dive brakes from Grumman; F6F is canceled, Grumman is tasked to develop the plane as light as FC12, but with R-2800 bubble canopy; Navy orders from Curtiss the FC12 with reinforced undercarriage to act as dive brake, plus LE slats; Navy tasks Wright to develop more powerful R-2600; Navy issues request for new all-around attack plane with R-3350
-mid-1943: the FC12B enters production (1750 HP, LE slats, dive bomb to 75 deg, 1500 lbs of bombs), produced also at GM as FM-2
(-late 1943: F4U is in use, F8F 1st flight)
-early 1944: Wright starts production of R-2600 with 1900 HP for T/O, water injection and defined WEP, resulting FC12C (with new engine cowling a-la IJA/IJN planes) making 400+ mph at 18 kft, WEP rating
(-late 1944: F8F in production, 2100 HP; 2400 HP in mid-45)


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> It was WEP figure, so I cut 10% to get military rating. It's 20% difference with R-2600, military rating.



It was not a WEP figure. Some figures for the V-1650-1. 
take off------------------1390hp/3000rpm?+14lbs boost.
max cont (climb)--------1125hp/2850rpm/+9/9,500ft low gear
max cont (climb)--------1130hp/2850rpm/+9/16,750ft high gear
Max power (combat)---1460hp/3000rpm/+14/6,250ft low gear
Max power (combat)---1430hp/3000rpm/+16/11,000ft low gear

1120hp at 18500ft is not out of line.





tomo pauk said:


> Perhaps you mean 'loaded' when stating 7100 lbs figure for P-40F?



Nope.
Sometimes I do make mistakes but in this case I am taking the numbers from the weight charts in "America's Hundred-Thousand" which gives a weigh of 7089lbs "basic" or empty equipped. there is a note that this particular aircraft was 109lbs over the guarantee weight however. To this weight is added 180lbs for pilot and chute, 98lb for oil, 423lbs for .50cal ammo and 888lbs for internal fuel bringing the gross weight to 8678lbs. to this could be added bombs or the ever popular drop tank. Weight for that is 0.5lbs extra piping, 5.0lbs for the rack, 8.6lbs for sway braces, 40lbs for the tank and 312lbs for the fuel. which would put the plane at over 9000lbs.




tomo pauk said:


> The empty weight that does not include guns radio is pretty vague number;



It is if you are trying to use it to predict performance.
It is somewhat more useful if you use it to compare two different planes to see how well the designer did at accommodating useful load. Add the disposable load (pilot, ammo, fuel,oil etc) to the military equipment (guns, armor, radio, oxygen,bombs if carried, etc) to get useful load. compare useful load to empty weight to see which designer built the lightest airplane to carry a given a load. 



tomo pauk said:


> The historical P-40 has had much greater range than Spit or Bf-109 (Wiki says as greater as 'double'), so the minor decrease wouldn't be that detrimental.



that is because it carried more fuel NOT including the drop tank. a P-40E might carry over 120imp gallons of fuel compared to the Spitfires 85Gals. hang 43 imp gal of drop tank underneath and the range does get impressive even if not quite a fair comparison. 

of course this a reason for using loaded weights (or partially loaded) when comparing performance. The larger heavier plane will look better when the larger, heavier load is taken out of it. 

This fuel thing is one reason the P-40 was always in trouble when compared to the Spitfire and Bf 109. Not the only reason but one of many. Not only do you have a larger fuel load but you have bigger fuel tanks so just not filling them all the way doesn't solve the problem. The unprotected tanks on the original P-40 weighed 171lbs (including pipes), the protected tanks on a P-40E weighed 425lbs. the P-40E is going to be carrying around roughly 130-140lbs more fuel tank even when empty than a Spitfire or 109. 

The idea of making the plane heavier while making the wing smaller might have a few problems too. While it helps straight line speed it does impose a few other penalties like higher landing speed.
see:http://www.zenoswarbirdvideos.com/Images/P-40/P-40TOCLC.pdf


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> The Navy use of such P-40 might have a clue... Alternate time line:
> 
> -1st aug 1940: after hearing of production of Army plane capable of 375 mph, Navy performs comparison against F2A F4F. 'P-40' soundly defeats the fixed-wing examples of those, so Navy orders a navalized version as a stop gap 'till F4U comes. Main shortcoming is low set pilot's seat.



I see, now we are not just substituting the the R-2600 for the allison in an existing airplane, the Allison powered P-40 is never ordered in this alternative time line.

The R-2600 powered plane is ordered back in the Spring of 1939?

well,it is you fantasy

a minor shortcoming might be that a P-40E had a much longer take-off roll than the Navy planes (like around double).


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## tomo pauk (Apr 3, 2010)

Down is what I was able to find out for Merlin XX (a.k.a V-1650-1), on P-40F:

So not the WEP indeed, but it also claims 90 HP less for take-off thany you do 
Other figures (but not for max power(combat) - never developed/confirmed for R-2600) seem comfortable within reach even for R-2600 of 1940.

Another question/confirmation - was the max speed reached with 'max power(combat)' - WEP (as I think it was the case)?

The another table (down) claims cca 700 lbs less for every weight category (also from 'P-40 in action'), confirming Wiki. In the Variants P-40F Warhawk, Kittyhawk II site they post another set of data (from Joe Baugher), with values in between (6600 empty) 

How about making a definitive guide to P-40?


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## tomo pauk (Apr 3, 2010)

Shortround6 said:


> I see, now we are not just substituting the the R-2600 for the allison in an existing airplane, the Allison powered P-40 is never ordered in this alternative time line.
> 
> The R-2600 powered plane is ordered back in the Spring of 1939?
> 
> well,it is you fantasy



Navy ordered R-2800-powered plane (F4U) in June 1938, so my idea is not that fantastic 



> a minor shortcoming might be that a P-40E had a much longer take-off roll than the Navy planes (like around double).



2 things 
- real P-40s (and P-47, for that matter) were flown from carriers
-we've just mounted more powerful engine to the airframe


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## tomo pauk (Apr 3, 2010)

The data from here:
http://www.raafwarbirds.org.au/targetvraaf/p40_archive/pdfs/1650-1.pdf
claims that WEP for V-1650-1 was 1300 HP, so those figures with 1450 HP don't seem OK 

Man, you really make me to do the homework


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> Navy ordered R-2800-powered plane (F4U) in June 1938, so my idea is not that fantastic
> 
> 
> 
> ...



Yep, but they were never flown into combat from a carrier.

The carrier was used as an aircraft ferry to get the planes close to a land base. Planes were flown ashore and serviced before being used in combat. this means that flight operations could be timed (within reason) for favorable weather conditions and it may mean that the fighters were flown off at less than full loads of fuel and/or ammunition since these loads would be added at the shore base.

your more powerful engine increased the weight which increased the wing loading which increased the minimum flying speed.


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## tomo pauk (Apr 3, 2010)

Seafires Mk.III (and other Seafires) were flown from RN carriers with bombs, despite having much thinner wing (= less lift for low speed); RN carriers were smaller then USN counterparts. 
Plus, I've proposed this in 'my' time line:


> -mid-1943: the FC12B enters production (1750 HP,* LE slats*, dive bomb to 75 deg, 1500 lbs of bombs), produced also at GM as FM-2


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> So not the WEP indeed, but it also claims 90 HP less for take-off thany you do



Might depend on manifold pressure used but 1300 is a fairly common number. 



tomo pauk said:


> Other figures (but not for max power(combat) - never developed/confirmed for R-2600) seem comfortable within reach even for R-2600 of 1940.


True


tomo pauk said:


> Another question/confirmation - was the max speed reached with 'max power(combat)' - WEP (as I think it was the case)?


Crappy answer----it depends. Since war emergency power is ONLY available BELOW the rated altitude of an engine (and the further below the the higher the power--within reason) and since the MAX speed of an aircraft was often reached within several thousand feet ABOVE the the rated altitude of the engine it may make no difference to the "book maximum speed". Max speed was were the thrust (power) was the greatest in relation to drag. As the airplane climbed, say to 20,000ft were the air is about 1/2 the density of sea level the drag is going to drop to 1/2 the drag at sea level. If the supercharged engine can provide enough power the plane will be faster at the higher altitude until engine power falls off faster than the drag is going down due to thinner air.

As a for instance and keeping with our P-40 motif, The P-40F is often quoted as being just a few mph faster than a P-40E for peak speed. While this is true what is often over looked is that the P-40F acieves this speed around 5,000ft higher than the P-40Eand at 20,000ft it is actually about 25-30mph faster than a P-40E and the higher you go the more advantage it has. The P-40F is slower than it's peak speed at any altitude below about 20,000ft and this is were WEP comes in. at about 12,000ft it may be doing 340mph instead of the 360+ it can do at 20,000ft. Using WEP may allow it to do 350 or a bit more (example don't quote this which while helpful in a fight doesn't change the max speed in the brochure


tomo pauk said:


> The another table (down) claims cca 700 lbs less for every weight category (also from 'P-40 in action'), confirming Wiki. In the Variants P-40F Warhawk, Kittyhawk II site they post another set of data (from Joe Baugher), with values in between (6600 empty)
> 
> weights can be all over the map. The weights I gave you were for a plane 109lbs over the manufactures guarantee weight which means it was 1.25% over weight, it could just as easily been 1-1.25% under weight and once again the 'empty weight" offers the most possibility for confusion. Americans changed their weight procedure to move armor and bullet proof glass from the useful load category to the "armament provisions" category included in empty weight between the E and F models. please note that "armament provisions" does not include the weight of the guns
> British "tare" weight often does not include the radio so a British prepared handbook will show different weights than an American handbook.
> ...


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> Seafires Mk.III (and other Seafires) were flown from RN carriers with bombs, despite having much thinner wing (= less lift for low speed); RN carriers were smaller then USN counterparts.
> Plus, I've proposed this in 'my' time line:



Spitfires had a lower wing loading to begin with and had a shorter take-off run. 

LE slats do squat for take off.


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## tomo pauk (Apr 3, 2010)

Shortround6 said:


> Spitfires had a lower wing loading to begin with and had a shorter take-off run.


Only the Seafire III (of fully navalized Sefires) had lower wing loading, but, since they managed to take off a) with bombs, and b) while using shorter deck, the navalized 'P-40s' would've be in no disadvantage there.
Later Seafires were as heavy as my 'P-40/F12C', and were still capable to take off with bombs.
The Spits have had thinner wings, so less lift there @ low speeds - advantage 'P-40'.



> LE slats do squat for take off.



Sorry, I disagree


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## tomo pauk (Apr 3, 2010)

Shortround6 said:


> ...
> ...
> 
> WEP is also limited by not exceeding allowable coolant/cylinder temperatures and oil temperatures, subject to being shot at



(in order not to quote the whole post)

Informative - thanks


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> Only the Seafire III (of fully navalized Sefires) had lower wing loading, but, since they managed to take off a) with bombs, and b) while using shorter deck, the navalized 'P-40s' would've be in no disadvantage there.



Would you please check your figures again, since no Seafire until the last ones ( MK 47? and such) went over 8000lbs in clean condition and NO P-40 after the C model was under 8000lbs clean (unless it had less than ful internal tanks) and since the normal Spitfire wing was slightly bigger than a P-40 wing I am having a a hard time figuring this one out.


tomo pauk said:


> The Spits have had thinner wings, so less lift there @ low speeds - advantage 'P-40'.


You are counting on a generality here and neither actual lift coefficients or measured performance. 




tomo pauk said:


> Sorry, I disagree



Well, if you can show me a lift to angle of attack chart that shows this to be true I might agree with you. Since the charts that show change in lift coefficients in relation to angle of attack don't show any real improvement over an unslatted wing until the slatted wing exceeds about a 12 degree angle of attack (and a max improvement at 18 or more degrees) I would say you are either using a very unconventional takeoff procedure or they don't do any good. Landing is another story where the glide slope angle can be combined with a nose up attitude to get the required angle of attack on the wing. 

this is in regards to leading edge slats or slots and not in reference to drooping leading edges which are not the same thing.


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## Shortround6 (Apr 3, 2010)

tomo pauk said:


> (in order not to quote the whole post)
> 
> Informative - thanks



You are welcome.
Some sources I am using for engine figures are "British Piston Aero-Engines and their Aircraft" by Alec Lumsden (some of the higher ones). 
"The Merlin in Perspective-the combat years" by Alec Harvey-Bailey and the Rolls-Royce Heritage trust.
Several editions of "Jane's all the Worlds Aircraft" and several editions of "Aircraft Engines of the World" by Paul Wilkinson.


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## tomo pauk (Apr 5, 2010)

I'll re-check the Seafire numbers when I return home; we're at Easter holidays @ my pop mum. My granpa was also here - a WW2 vet, no less


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## tomo pauk (Apr 5, 2010)

Shortround6 said:


> Would you please check your figures again, since no Seafire until the last ones ( MK 47? and such) went over 8000lbs in clean condition and NO P-40 after the C model was under 8000lbs clean (unless it had less than ful internal tanks) and since the normal Spitfire wing was slightly bigger than a P-40 wing I am having a a hard time figuring this one out.



Down is the excerpt from book 'Seafire' - all other fully navalized Seafires after Mk.III (=Merlin aboard) have had Griffon installed, and weighted from 7000 lbs empty on - same 7000 lbs I was estimating for fully navalized 'my' P-40.
Wing area was 236 ft^2 vs. 242 for Seafires = 2.5% (negligible) advantage Seafire. As you see on the table, they could take off with 500lb bomb, even from RN (= smaller than USN) carriers.



> You are counting on a generality here and neither actual lift coefficients or measured performance.



I admit that I have not dug uut the exact figures for lift coefficients; please toss some info if you find it before I do. However, I still believe that ticker wing of P-40 provided more lift 



> Well, if you can show me a lift to angle of attack chart that shows this to be true I might agree with you. Since the charts that show change in lift coefficients in relation to angle of attack don't show any real improvement over an unslatted wing until the slatted wing exceeds about a 12 degree angle of attack (and a max improvement at 18 or more degrees) I would say you are either using a very unconventional takeoff procedure or they don't do any good. Landing is another story where the glide slope angle can be combined with a nose up attitude to get the required angle of attack on the wing.
> 
> this is in regards to leading edge slats or slots and not in reference to drooping leading edges which are not the same thing.



No such detailed info from me yet, but, again, toss any info (table, drawing etc) that could prove your or my claim.
FWIW, some of CV planes sported the slats (SB2C eg.), so think my claim has merit.


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## tomo pauk (Apr 5, 2010)

In my favourite master-slave vogue, here is the beefed-up P-39. The slave engine supercharger is mounted instead of 37mm, 2 x 0,50in, their ammo, and synchro gear. 4 x .50in in wings.
Sure enough, turbo-supercharger might have been installed, with exhaust gasses transferred to front (second pic).


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## zoomar (Apr 5, 2010)

Sort of off the topic, but related to re-engining planes, are there detailed plans that show what the initial Rolls-Royce proposal to mount a Merlin Engine behind the cockpit in the P-51 would have looked like? I've seen photos of the mock up taken from a bad angle, but no actual drawings.


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## tomo pauk (Apr 5, 2010)

Not the P-47, nor the P-44, but P-43 with R-2600; hull .50in MGs moved to wing:


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## zoomar (Apr 5, 2010)

zoomar said:


> Sort of off the topic, but related to re-engining planes, are there detailed plans that show what the initial Rolls-Royce proposal to mount a Merlin Engine behind the cockpit in the P-51 would have looked like? I've seen photos of the mock up taken from a bad angle, but no actual drawings.



Oh, never mind 

http://www.ww2aircraft.net/forum/aircraft-pictures/mid-engined-p-51-a-24041.html


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## tomo pauk (Apr 5, 2010)

I've attached a table from manual for Fw-190A-8 (dated sept 1944), showing that it wouldn't enjoy any power-to-weight-related advantage vs. my proposed designs ('P-40' P-43) using R-2600 (1700 HP in 1942, 1750 in 1943, 1900 in 1944, without any development it might have received). 

Eg. the R-2600 from 1943 was able to produce:


> Power output:
> 
> * 1,750 hp (1,305 kW) at 2,600 rpm at 3,200 ft (975 m) military power
> * 1,450 hp (1,080 kW) at 2,600 rpm at 15,000 ft (4,575 m) military power


while driving planes of well under 7000 lbs empty equipped.


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## tomo pauk (Apr 5, 2010)

In order to avoid problems with BMW-engined Fw-190, RLM might have ordered such a hybrid: Fw-190 with DB-601E/605A.
3 cannons (one central, two in wings - firing out of prop disc), glycol radiator under the engine, in enlarged cowling together with oil radiator. Though nominally with 10% less power, the weight would've also go down (no hull MGs, their ammo synchro gear), while DBs offered greater reliability then 801 prior 1943. And difference of power at altitude would've been negligible. Drag would've been reduced a tad.
The versions with 1800-2000 HP in DB-605AS/AM/D would've been awesome.

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## Shortround6 (Apr 5, 2010)

tomo pauk said:


> Down is the excerpt from book 'Seafire' - all other fully navalized Seafires after Mk.III (=Merlin aboard) have had Griffon installed, and weighted from 7000 lbs empty on - same 7000 lbs I was estimating for fully navalized 'my' P-40.
> Wing area was 236 ft^2 vs. 242 for Seafires = 2.5% (negligible) advantage Seafire. As you see on the table, they could take off with 500lb bomb, even from RN (= smaller than USN) carriers.



The US Navy and the RN operated a bit different. US Navy liked to use large deck parks (many aircraft occupying the aft end of the flight deck) and while they could catapult some aircraft the idea was to fly off as many as possible without using catapults for a much faster pace of operations. This obviously limits the take-off distance to somewhat less than the full length of the carrier. The RN was much more likely to only have a few planes on deck at a time , slower pace but higher percentage of deck available. 




tomo pauk said:


> I admit that I have not dug uut the exact figures for lift coefficients; please toss some info if you find it before I do. However, I still believe that ticker wing of P-40 provided more lift



Well, for an early Spit
fire see: Spitfire Mk I N.3171 Trials Report

Notice the difference just propellers can make.

For a later Spitfire see: http://www.spitfireperformance.com/spitfire-fix-ads.jpg

500yds to 50ft at 7450lbs

For a P-40E see: http://www.zenoswarbirdvideos.com/Images/P-40/P-40TOCLC.pdf

1800ft (600yds) to 50 ft at 7500lbs. 

Granted the MK IX has a bit more power but I am not seeing a advantage to the P-40s thicker wing.




tomo pauk said:


> No such detailed info from me yet, but, again, toss any info (table, drawing etc) that could prove your or my claim.
> FWIW, some of CV planes sported the slats (SB2C eg.), so think my claim has merit.



See: chapt4

GO down to figure #63

quote"Slots.- The maximum coefficient of lift may be increased through the use of a slot formed by a leading-edge auxiliary airfoil called a slat. Figure 63(a) illustrates the operating principle. When the slot is open, the air flows through the slot and over the airfoil. The slot is a boundary-layer control device and the air thus channeled energizes the boundary layer about the wing and retards the separation. The airfoil can then be flown at a higher angle of attack before stall occurs and thus get a higher... CL,max value. A curve showing CL as a function of a [Greek letter alpha] for the normal and the slotted airfoil is given in figure 63(b). Notice particularly that for angles of attack less than the stall angle, the airfoil lift curve is relatively unaffected whether the slot is opened or closed."

Slats do work for landing and they help a lot with maintaining aileron control at speeds close to stall. 

I have seen other charts and have a few in books but my scanner skills are weak


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## Shortround6 (Apr 5, 2010)

tomo pauk said:


> I've attached a table from manual for Fw-190A-8 (dated sept 1944), showing that it wouldn't enjoy any power-to-weight-related advantage vs. my proposed designs ('P-40' P-43) using R-2600 (1700 HP in 1942, 1750 in 1943, 1900 in 1944, without any development it might have received).
> 
> Eg. the R-2600 from 1943 was able to produce:
> 
> while driving planes of well under 7000 lbs empty equipped.




Where are you getting the "well under 7000 lbs empty equipped"from?

The Fw 190 you are quoting is listed as 7608lbs empty equipped. Granted it has 2 to 2 1/2 times the fire power of a four .50 cal plane (or more) .

An old book lists weights for the FW 190A-3 as 6,393lbs empty, 7,110lbs empty equipped and 8770lbs loaded. This is for 7.9mm cowl guns, MG 151 in the wing roots and MG/FF guns in the wings. 

Empty equipped for a P-40E is 6700lbs and for the F is 6980lbs and that is with engine weights 3-400lbs lighter than the R-2600 (including radiator and coolant) . Dropping a pair of .50 cal guns isn't going to cut it. Chopping the wing to 200sq ft might save you 172lbs at the very best. 

As far as the comparisons to the FW 190 goes the R-2600 cowling is going to be 6-8in bigger in diameter than the BMW 801 cowling. This trivial 6in increase actually means about a 24% increase in frontal area. 
As your own figures show the FW 190 has about a 3,700ft altitude advantage. or to put it another way the R-2600 would be putting out approximately 1250hp at the altitude the FW has 1420Hp. 

By the way the R-2600 received a fair amount of development, Difference between 1600hp and 1700hp models was a change from a forged aluminum crankcase to a forged steel crankcase among other things. The Steel crankcase had the strength to allow for the higher rpm. The 1900hp models changed from cast cylinder heads to forged heads and changed from machined cooling fins on the cylinder barrels to sheet metal fins rolled in machined grooves called "W" fins. Considerable retooling of the factory was needed to change over. The Stronger cylinder heads and much increased cooling fin area allowed for the higher power output. There may have been other changes too.


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## tomo pauk (Apr 6, 2010)

Shortround6 said:


> The US Navy and the RN operated a bit different. US Navy liked to use large deck parks (many aircraft occupying the aft end of the flight deck) and while they could catapult some aircraft the idea was to fly off as many as possible without using catapults for a much faster pace of operations. This obviously limits the take-off distance to somewhat less than the full length of the carrier. The RN was much more likely to only have a few planes on deck at a time , slower pace but higher percentage of deck available.



Okay, then we'd launch Dauntleses 1st 


> Well, for an early Spit
> fire see: Spitfire Mk I N.3171 Trials Report
> 
> Notice the difference just propellers can make.
> ...



Tnx for a thorough info.
The Mk.IX have had 25% more power for take off than P-40E later, and that is quite a lot. The R-2600 of the same era have had the same power for TO as Merlin 60 series




> See: chapt4
> 
> GO down to figure #63
> 
> ...



I think that pushing a plane to take advantage of greater AoA would permit it to reduce TO distance, or to take off with greater load from same TO strip.


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## tomo pauk (Apr 6, 2010)

Shortround6 said:


> Where are you getting the "well under 7000 lbs empty equipped"from?



P-40F (6 MGs) was 6300 lbs empty equipped. We delete 2 MGs and their ammo (-180 lbs for guns only), and substitute the engines (+400 lbs, if even so). Result is circa 6500 lbs for P-40 with R-2600.



> The Fw 190 you are quoting is listed as 7608lbs empty equipped. Granted it has 2 to 2 1/2 times the fire power of a four .50 cal plane (or more) .



Of course, but we do not need such firepower - no heavy bombers to take down.


> An old book lists weights for the FW 190A-3 as 6,393lbs empty, 7,110lbs empty equipped and 8770lbs loaded. This is for 7.9mm cowl guns, MG 151 in the wing roots and MG/FF guns in the wings.



Yep, think those figures are pretty accurate - the A8 paid the price for it's heavy punch. OTOH, the engine of A3 not as reliable as later BMWs, nor as many contemporary Allied Axis engines in wide use, and the plane would be still some 600 lbs heavier then a 4-gun P-40 with R-2600.


> Empty equipped for a P-40E is 6700lbs and for the F is 6980lbs and that is with engine weights 3-400lbs lighter than the R-2600 (including radiator and coolant) . Dropping a pair of .50 cal guns isn't going to cut it. Chopping the wing to 200sq ft might save you 172lbs at the very best.



Please re-check your figures. Down is the table with weight for P-40N variant that reinforce my figures. 



> As far as the comparisons to the FW 190 goes the R-2600 cowling is going to be 6-8in bigger in diameter than the BMW 801 cowling. This trivial 6in increase actually means about a 24% increase in frontal area.



The difference in engine diameters is 4in, so the cowl would've been that much wider.



> As your own figures show the FW 190 has about a 3,700ft altitude advantage. or to put it another way the R-2600 would be putting out approximately 1250hp at the altitude the FW has 1420Hp.



Sure, but it has to pull a 1000 lbs heavier plane 



> By the way the R-2600 received a fair amount of development, Difference between 1600hp and 1700hp models was a change from a forged aluminum crankcase to a forged steel crankcase among other things. The Steel crankcase had the strength to allow for the higher rpm. The 1900hp models changed from cast cylinder heads to forged heads and changed from machined cooling fins on the cylinder barrels to sheet metal fins rolled in machined grooves called "W" fins. Considerable retooling of the factory was needed to change over. The Stronger cylinder heads and much increased cooling fin area allowed for the higher power output. There may have been other changes too.



Of course it received the development, but never received ADI, nor it was tasked to qualify for military rating.


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## Shortround6 (Apr 6, 2010)

tomo pauk said:


> I think that pushing a plane to take advantage of greater AoA would permit it to reduce TO distance, or to take off with greater load from same TO strip.



Uh, pushing a plane to take advantage of a greater angle of attack how?

Plane accelerates down the strip, tail comes up and angle of attack on the wing falls to near zero, Or for trike gear aircraft angle of attack stays low until nose wheel comes of the ground. 
Trying to pull the plane up too soon means it stalls and crashes back on the runway or you force the tail back down and increase drag while partially blocking the tail surfaces. 

The idea is to get to flying speed as soon as possible. I still can't see how trying to taxi/accelerate down the runway/carrier deck with the wing tilted at 12 degrees or better is really going to work.


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## Shortround6 (Apr 6, 2010)

tomo pauk said:


> P-40F (6 MGs) was 6300 lbs empty equipped. We delete 2 MGs and their ammo (-180 lbs for guns only), and substitute the engines (+400 lbs, if even so). Result is circa 6500 lbs for P-40 with R-2600.


The 6300lb figure is without guns.




tomo pauk said:


> Of course, but we do not need such firepower - no heavy bombers to take down.



You can guarantee that in 1940? that the Germans or Japanese will not develop a 4 engine bomber in the next 3-4 years. You weight comparison is done much good by using the weight of the particularly heavily armed A-8 model.



tomo pauk said:


> Yep, think those figures are pretty accurate - the A8 paid the price for it's heavy punch. OTOH, the engine of A3 not as reliable as later BMWs, nor as many contemporary Allied Axis engines in wide use, and the plane would be still some 600 lbs heavier then a 4-gun P-40 with R-2600.



What has reliability of the early engine got to do with weight of the entire airplane. ? 



tomo pauk said:


> Please re-check your figures. Down is the table with weight for P-40N variant that reinforce my figures.



you may want to recheck your own figures, you picked the lightest P-40 built since the C model. How did they achieve this? one trick was using aluminum radiators, another was using just 4 guns (you not only save the weight of the guns but the mounts, charging equipment ammo boxes etc), another trick was leaving out the forward fuel tank (and self sealing) reducing internal fuel capacity to 120 US gallons. reductions in landing gear weight and armor may have also helped. 
Later versions of the "N" model with the forward fuel tank replaced and provisions for 6 guns went up to 6200lbs empty. of course reducing the weight of the radiators just increases the difference of the weight installation when you switch to the aircooled engine. The Allison also weighed around 180lbs less than the Merlin in the "F".

Comparing a heavily armed A-8 model FW to a special "stripper" model of the P-40 (only 400 built) doesn't seem a fair weight comparison. 




tomo pauk said:


> The difference in engine diameters is 4in, so the cowl would've been that much wider.


The 52in diameter for the BMW engine includes the cowl. The BMW engine was noted for how tight the cowl was in relation to other radial engines. I have seen one dimension of 60in for the diameter of an A-20 cowl so I figured 58in wasn't a bad compromise. Unless of course your alternative time line has the US beating the Germans to the punch with the whole tight cowl fan cooling thing. Incorporating the oil cooler into the cowling leading edge was another low drag trick the Germans used on the Fw 190 which no WW II US plane copied. How much lower in drag than a standard oil cooler I don't know but you rarely get something for nothing.




tomo pauk said:


> Sure, but it has to pull a 1000 lbs heavier plane



want to recheck that in light of the above. 




tomo pauk said:


> Of course it received the development, but never received ADI, nor it was tasked to qualify for military rating.



You have been quoting military ratings for R-2600. 
Military is not WEP. 
Please note the changes I gave you before and add to them a change in master rod bearing material and increased strength rods and crankshaft. 
ADI is not magic. It does several things to help an engine develop power. 
One thing it cannot do is increase the airflow of a supercharger. ADI systems only increase the power of an engine below it's rated or critical altitude. 
It helps cool the incoming charge, this allows more boost to be used before detonation(assuming the supercharger can supply more boost). More boost means more pressure in the cylinders and acting on the crankshaft, rods and crankcase. While ADI can help in making more power it does nothing in helping an engine stand up to the extra stress.
ADI also acts as an internal engine coolant, it helps cool the inside of the cylinders, piston tops, head areas etc. while this may allow for some increase in power without additional fins or liquid circulation the question maybe how much on a particular engine. Please note the P&W smaller cylinders on the R-2800 meant that they were a bit easier to cool in theory.
Another thing that ADI allowed was that it traded ADI fluid for fuel. Many engines in high boost conditions used extra fuel as an internal coolant, detonation suppressant. As a for instance, one version of the BMW 801 D could inject from 14.3 to 39 gallons an hour (depending on which part of the source you believe) into the supercharger allowing a 3.3lb increase in boost good for 140hp at sea level. 
ADI allowed for the increase in power at the lower fuel consumption and the ADI tank didn't have to have the heavy self sealing liner/coatings. 
How much ADI can be used depends on the capacity of the supercharger to begin with, the strength of the engine and the ability of the engine to stay in temperature operating limits even with the ADI. 

You are no longer talking about swapping one existing engine for another but coming up with new lines of development for engines that they may not have been able to support. Again please note the considerable upgrades and re-tooling of the factories (changing from thousands of cast cylinder heads per week to thousands of forged heads,etc) needed to go from 1600hp to 1900hp. The R-2600 may not have been able to meet the military's requirements for WEP (7.5 hours at WEP on a test stand in, I believe, 5 minute spurts with cool down periods between.)

I may not be the only person who thinks the R-2600 was too wide. Wright developed and tested a short stroke version, the R-2170 with the stroke reduced to 5.25 in but with a much reduced diameter of 47in. It did not go into production however. Sorry, but I have no power figures available.


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## tomo pauk (Apr 7, 2010)

Shortround6 said:


> Uh, pushing a plane to take advantage of a greater angle of attack how?
> 
> Plane accelerates down the strip, tail comes up and angle of attack on the wing falls to near zero, Or for trike gear aircraft angle of attack stays low until nose wheel comes of the ground.



The idea is that pilot would've pull the stick when he reaches last 80% of runaway. That way he'd increase AoA ( as much as tail allows) lift.



> Trying to pull the plane up too soon means it stalls and crashes back on the runway or you force the tail back down and increase drag while partially blocking the tail surfaces.



It wouldn't crash since the deployed slats would allow 'better' airflow and therefore prevent the stall.



> The idea is to get to flying speed as soon as possible. I still can't see how trying to taxi/accelerate down the runway/carrier deck with the wing tilted at 12 degrees or better is really going to work.



The stronger engine would've allowed for better acceleration.


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## tomo pauk (Apr 7, 2010)

Shortround6 said:


> The 6300lb figure is without guns.



You might be right (I was mistaken many times  ), but please post some table or something like that 




> You can guarantee that in 1940? that the Germans or Japanese will not develop a 4 engine bomber in the next 3-4 years.



The P-40B was produced with 2 HMGs 4 LMGs - the 4 HMGs are at least on par with that, more so since the HMGs rate of fire would have not been notably reduced by prop rotation. Not to mention P-40B (of 1940) was lacking the engine power to compete vs. those (anticipated) targets. 
The US have had P-38 ready for production, just aiming at those bombers.



> You weight comparison is done much good by using the weight of the particularly heavily armed A-8 model.



I've agreed with your figures for the A-3 (lightest?) version, and that one too would be in hardly any advantage vs. the opposite number (7100 lbs vs 6500 lbs for 'P-40N' with R-2600) if we talk about power-to-weight ratio.



> What has reliability of the early engine got to do with weight of the entire airplane. ?


 
Pushing a not-so-reliable engine to extract some extra mph from a hefty plane is not very viable, more so if done time again.



> you may want to recheck your own figures, you picked the lightest P-40 built since the C model. How did they achieve this? one trick was using aluminum radiators, another was using just 4 guns (you not only save the weight of the guns but the mounts, charging equipment ammo boxes etc), another trick was leaving out the forward fuel tank (and self sealing) reducing internal fuel capacity to 120 US gallons. reductions in landing gear weight and armor may have also helped.
> Later versions of the "N" model with the forward fuel tank replaced and provisions for 6 guns went up to 6200lbs empty. of course reducing the weight of the radiators just increases the difference of the weight installation when you switch to the aircooled engine. The Allison also weighed around 180lbs less than the Merlin in the "F".



Well, what ever they did to save weight is indeed applicable to 'my' P-40 (minus the reduction of glycol radiator); we can add 50-100 lbs and be done with that 
That's 6600 lbs at most, again favorably vs. any Fw-190.


> Comparing a heavily armed A-8 model FW to a special "stripper" model of the P-40 (only 400 built) doesn't seem a fair weight comparison.



Answered above 




> The 52in diameter for the BMW engine includes the cowl. The BMW engine was noted for how tight the cowl was in relation to other radial engines. I have seen one dimension of 60in for the diameter of an A-20 cowl so I figured 58in wasn't a bad compromise. Unless of course your alternative time line has the US beating the Germans to the punch with the whole tight cowl fan cooling thing. Incorporating the oil cooler into the cowling leading edge was another low drag trick the Germans used on the Fw 190 which no WW II US plane copied. How much lower in drag than a standard oil cooler I don't know but you rarely get something for nothing.



Im 'my' time line, the P-40 would receive the R-2600 ('stead of V-1710) in 1940. My guess is that they would do something about the cowl in years after that. And I've already proposed clipping the wings, canceling a lot of added drag of R-2600, and some added weight. 



> want to recheck that in light of the above.



Think I did that (not that I claim I know everything).




> You have been quoting military ratings for R-2600.
> Military is not WEP.



Sorry fo the typo; I've ment WEP was not developed, not military rating.



> Please note the changes I gave you before and add to them a change in master rod bearing material and increased strength rods and crankshaft.
> ADI is not magic. It does several things to help an engine develop power.
> One thing it cannot do is increase the airflow of a supercharger. ADI systems only increase the power of an engine below it's rated or critical altitude.
> It helps cool the incoming charge, this allows more boost to be used before detonation(assuming the supercharger can supply more boost). More boost means more pressure in the cylinders and acting on the crankshaft, rods and crankcase. While ADI can help in making more power it does nothing in helping an engine stand up to the extra stress.
> ...



Informative as always 


> You are no longer talking about swapping one existing engine for another but coming up with new lines of development for engines that they may not have been able to support. Again please note the considerable upgrades and re-tooling of the factories (changing from thousands of cast cylinder heads per week to thousands of forged heads,etc) needed to go from 1600hp to 1900hp. The R-2600 may not have been able to meet the military's requirements for WEP (7.5 hours at WEP on a test stand in, I believe, 5 minute spurts with cool down periods between.)



I was giving the figures for off-the-shelf engines, available as in original time line all the times.
The ADI and WEP were never developed because nobody was requesting them - no fighter design ever used R-2600 in the 1st place.



> I may not be the only person who thinks the R-2600 was too wide. Wright developed and tested a short stroke version, the R-2170 with the stroke reduced to 5.25 in but with a much reduced diameter of 47in. It did not go into production however. Sorry, but I have no power figures available.



Since R-2170 never went into production, perhaps they were wrong about that 


Have you notice that original P-40 was never talked as able to take at any Fw-190


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## Shortround6 (Apr 7, 2010)

tomo pauk said:


> The idea is that pilot would've pull the stick when he reaches last 80% of runaway. That way he'd increase AoA ( as much as tail allows) lift.



He also increases drag. Please note that this trick would work with a normal wing if it worked at all because the normal wing has a much higher coefficient of lift at 10 degrees than it does at 0-5 degrees that wing may be operating at in a normal take-off. 




tomo pauk said:


> It wouldn't crash since the deployed slats would allow 'better' airflow and therefore prevent the stall.


slats don't create ANY lift. the allow the wing to operate at a higher angle of attack than normal and it is the higher angle of attack that creates the lift. For the slats to work at all (even a few percent) the AoA has to exceed 12-13 degrees, for them to really work the AoA is more like 16-22 degrees. 

this trick might work for changing the distance to clear an obstacle at the end of the runway. Once the plane is flying at 10-20 ft and with a little extra speed pulling back might help the climb out. But I would certainly want to check with an experienced pilot before trying it.

See:http://lets-go-fly.com/Lift and Drag curves for the Wing.pdf


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## Shortround6 (Apr 7, 2010)

tomo pauk said:


> You might be right (I was mistaken many times  ), but please post some table or something like that



Weight figures are from "America's Hundred-Thousand" by by Francis Dean, Schiffer Military History. 
With your interest in aircraft I would strongly recommend getting this book as it has weight break downs for eleven Major US fighters (sometimes for a number of models of each) along with many other details. It may have a few errors (what large book doesn't) but as a one volume resource for US fighters it is hard to beat it's value. 





tomo pauk said:


> The P-40B was produced with 2 HMGs 4 LMGs - the 4 HMGs are at least on par with that, more so since the HMGs rate of fire would have not been notably reduced by prop rotation. Not to mention P-40B (of 1940) was lacking the engine power to compete vs. those (anticipated) targets.
> The US have had P-38 ready for production, just aiming at those bombers.



Being on a par with less than adequate is not a good recommendation.
The US, rightly or wrongly was looking for heavy armament in 1940. Saying the US should have adopted a 4 gun fighter in 1940 because they historical didn't need to shoot down 4 engine bombers 2-4 years later seems a poor argument when one looks at the designs they were considering and which ones they adopted. 733 P-47Bs with R-2800s and 8 guns are ordered in Sept of 1940. This is after the meeting in June (before the BoB) when Republic is told that both the P-44 (a P-43 with an R-2180 engine) and Allison powered XP-47 are to be dropped and a plane using the R-2800 is wanted. 




tomo pauk said:


> I've agreed with your figures for the A-3 (lightest?) version, and that one too would be in hardly any advantage vs. the opposite number (7100 lbs vs 6500 lbs for 'P-40N' with R-2600) if we talk about power-to-weight ratio.



I am not agreeing with your 6500lb R-2600 powered P-40. Even taking a P-40C at 6143lbs and yanking 1649lb worth of engine and cooling system and adding 1950lbs worth of R-2600 is going to push you to 6444lbs, changing from 4 .30 cal guns to 2 .50s is going to add another 50lbs for 6494lbs.

Right on the money you say!!

Of course your 1700hp , 2600cu in engine still has the same oil system as the 1090hp, 1701 cu in engine, the same propeller, the same starter, exhaust system weight, engine mount weight and so on......right?




tomo pauk said:


> Pushing a not-so-reliable engine to extract some extra mph from a hefty plane is not very viable, more so if done time again.



Still has nothing to with estimating performance on a power to weight ratio does it.




tomo pauk said:


> Well, what ever they did to save weight is indeed applicable to 'my' P-40 (minus the reduction of glycol radiator); we can add 50-100 lbs and be done with that
> That's 6600 lbs at most, again favorably vs. any Fw-190.



Reducing the fuel capacity for a larger, thirstier engine doesn't seem like a good idea. First P40N-1 is delivered in March of 1943. 



tomo pauk said:


> Answered above



Really


tomo pauk said:


> Im 'my' time line, the P-40 would receive the R-2600 ('stead of V-1710) in 1940. My guess is that they would do something about the cowl in years after that. And I've already proposed clipping the wings, canceling a lot of added drag of R-2600, and some added weight.



Well, that leaves you with the high drag cowl in 1940-41-42, and I rather doubt clipping the wing is really going to do that much. The Fw 190 was first built with about a 160sq ft wing and changing to the 196sq ft wing only cost them 6mph. As far as weight goes I gave you 172lbs max, that is from dividing the weigh of the wing of a late model P-40 (see book listed above) by the wing area and then multiplying the weight per sq ft by your 36 sq ft reduction. of course this assumes that the weight of the wing is constant per sq ft which it is not. outer sections of wing using smaller, lighter ribs and thinner lighter spar sections.


tomo pauk said:


> I was giving the figures for off-the-shelf engines, available as in original time line all the times.
> The ADI and WEP were never developed because nobody was requesting them - no fighter design ever used R-2600 in the 1st place.



Some of those Avengers and Helldivers might have wanted a bit more power getting off those flight decks, what do you know......they got it!!! when Wright could supply it. 
Same with A-20s and B-25s.
Martin Mariner flying boats even got fan cooled engines to help cure chronic overheating, next model just shifted to R-2800s
Trying to haul a 55,000lb plane out of the water is not easy for one pair of engines
One problem that Wright had was that the father of the R-2600 was sent home and placed in virtual isolation because he was German. A majority of the rest of the engineering staff was trying to turn the R-3360 into a working engine. Just adding 2 cylinders per row to the R-2600 wouldn't seem like a big deal but it turned into a nightmare for Wright and took years (work started in 1936). 
More or faster work on R-2600 may mean the R-3360 is even later in development.




tomo pauk said:


> Since R-2170 never went into production, perhaps they were wrong about that



Well, you might look at the two P&W R-2180s for hints. 

Here is a hint for you though. The lead sentence in the wiki entry "The Pratt Whitney R-2180-A Twin Hornet and R-2180-E Twin Wasp E were closely-related radial engines developed in the United States by Pratt Whitney." is wrong. 



tomo pauk said:


> Have you notice that original P-40 was never talked as able to take at any Fw-190



I have noticed that
Since I don't believe that your R-2600 powered version is going to show any large advantage over the P-40F it does bring us back to the question of why bother.


----------



## tomo pauk (Apr 7, 2010)

Shortround6 said:


> Weight figures are from "America's Hundred-Thousand" by by Francis Dean, Schiffer Military History.
> With your interest in aircraft I would strongly recommend getting this book as it has weight break downs for eleven Major US fighters (sometimes for a number of models of each) along with many other details. It may have a few errors (what large book doesn't) but as a one volume resource for US fighters it is hard to beat it's value.



Yep, some 35-45 USD +p&p - quite a bargain when comparing what they require for not as good books in Croatian book stores. 




> Being on a par with less than adequate is not a good recommendation.
> The US, rightly or wrongly was looking for heavy armament in 1940. Saying the US should have adopted a 4 gun fighter in 1940 because they historical didn't need to shoot down 4 engine bombers 2-4 years later seems a poor argument when one looks at the designs they were considering and which ones they adopted. 733 P-47Bs with R-2800s and 8 guns are ordered in Sept of 1940. This is after the meeting in June (before the BoB) when Republic is told that both the P-44 (a P-43 with an R-2180 engine) and Allison powered XP-47 are to be dropped and a plane using the R-2800 is wanted.



Even better - the USAAC have had 2 world beater designs then  
'My' P-40s/P-43s would've provided numbers required at 'low' part of high-low mix, like P-40 originally did.



> I am not agreeing with your 6500lb R-2600 powered P-40. Even taking a P-40C at 6143lbs and yanking 1649lb worth of engine and cooling system and adding 1950lbs worth of R-2600 is going to push you to 6444lbs, changing from 4 .30 cal guns to 2 .50s is going to add another 50lbs for 6494lbs.
> 
> Right on the money you say!!
> 
> ...



Okay, than we'd add some 300 lbs for beefed-up stuff (exhaust, prop, starter, engine mount), but also remove at least 100 lbs from reduced wing. 'My' P-40C would've been 8% heavier then, but engine power would be 40-50% greater. Comparable with achievements of Spit IX-> Spit XIV, or LaGG-3 -> La5.



> Reducing the fuel capacity for a larger, thirstier engine doesn't seem like a good idea. First P40N-1 is delivered in March of 1943.



We'd trade off some of range to achieve much greater performance.



> Really



Yep 



> Well, that leaves you with the high drag cowl in 1940-41-42, and I rather doubt clipping the wing is really going to do that much. The Fw 190 was first built with about a 160sq ft wing and changing to the 196sq ft wing only cost them 6mph. As far as weight goes I gave you 172lbs max, that is from dividing the weigh of the wing of a late model P-40 (see book listed above) by the wing area and then multiplying the weight per sq ft by your 36 sq ft reduction. of course this assumes that the weight of the wing is constant per sq ft which it is not. outer sections of wing using smaller, lighter ribs and thinner lighter spar sections.



While we'd never know just how much the smaller wing would've canceled the enlarged engine, I've acknowledged the higher drag of it, and suggested the clipped wing as the most obvious/the easiest way of reducing wing's drag. Granted, if the R-2600 was ever mounted on a such streamlined design, like Spit, Bf-109, or P-51, the influence of draggier engine would've been more pronounced than with not-so-sleek P-40 hull.



> Some of those Avengers and Helldivers might have wanted a bit more power getting off those flight decks, what do you know......they got it!!! when Wright could supply it.
> Same with A-20s and B-25s.
> Martin Mariner flying boats even got fan cooled engines to help cure chronic overheating, next model just shifted to R-2800s
> Trying to haul a 55,000lb plane out of the water is not easy for one pair of engines



Never said that R-2600 received no development, but that it never received fighter-plane accessories (ADI, WEP qualification, perhaps a supercharger set for hi-alt work?). I so speak affirmatively about it - hence 'my' P-40 



> One problem that Wright had was that the father of the R-2600 was sent home and placed in virtual isolation because he was German.



Granted, you're very knowledgable man 



> A majority of the rest of the engineering staff was trying to turn the R-3360 into a working engine. Just adding 2 cylinders per row to the R-2600 wouldn't seem like a big deal but it turned into a nightmare for Wright and took years (work started in 1936).
> More or faster work on R-2600 may mean the R-3360 is even later in development.



Perhaps some of stuff developed for R-2600 would've ease the R-3360 development?



> Well, you might look at the two P&W R-2180s for hints.



I could ( will, provided I have time), but I've never had love for those 'intermediate' engines. No niche for those, you know...


> Here is a hint for you though. The lead sentence in the wiki entry "The Pratt Whitney R-2180-A Twin Hornet and R-2180-E Twin Wasp E were closely-related radial engines developed in the United States by Pratt Whitney." is wrong.



I take Wiki as reference only when lacking something better 



> I have noticed that
> Since I don't believe that your R-2600 powered version is going to show any large advantage over the P-40F it does bring us back to the question of why bother.



The difference vs. the P-40N would be indeed small, but the -F presented only 10% of P-40s produced. 'My' P-40 would've been vastly better than Allison-engined planes, and that is it's main quality


----------



## Shortround6 (Apr 7, 2010)

tomo pauk said:


> .
> Okay, than we'd add some 300 lbs for beefed-up stuff (exhaust, prop, starter, engine mount), but also remove at least 100 lbs from reduced wing. 'My' P-40C would've been 8% heavier then, but engine power would be 40-50% greater. Comparable with achievements of Spit IX-> Spit XIV, or LaGG-3 -> La5.



For now lets stick to 1940. The R-2600 available at this time is the 1600hp for take-off version, the "A" series. It has the Aluminum crankcase. It is good for 1600hp at take-off, 1600hp at 3000ft military power in low gear and 1400hp at11,500ft in high gear. 
For an idea of performance lets look at the P-40 in 1940, two, 50cal guns no armor or self sealing tanks and an Allison engine of 1040 for take off and 1030hp at 14300ft or 1090hp at 13,200ft depending on source (although with 60hp less at 900ft higher they aren't that far apart) at a weight of 6,787lbs gross it manages 357mph at 15,000ft. 
Now for an Idea of what the V-12 engine got for it's 'streamlining' we have the numbers for a Curtiss Hawk 75A-4. Poweerd by a 9 cylinder Wright cyclone of 1200hp for take off and Military ratings of 1200hp at 1800ft and 1000hp at 13,600ft. Speed is 323mph at 15,100ft and 272mph at sea level at a weight of 5,750lbs. again no armor, self sealing tanks but with 4 wing guns crating a bit of drag. 

V-12 engined plane with 45-50 more HP is about 10% faster while weighing 1,000lbs more.

The 1940 R-2600 doesn't have 40-50% more power at altitude (13-15,000ft) but 30% or under. At sea level it has 33% more power than the cyclone 9. 
The R-2600 weighs 600lbs more than the Cyclone for a dry, bare engine. Over 40% more.
Using the Hawk 75 as a basis and since drag goes up with the square of the speed you need 21% more power for a 10% increase in speed if everything stays the same. Since it didn't (heavier engine, heavier armament etc) you need even more power for a 10% increase in speed.
Would your R-2600 powered plane be faster than a P-40?
quite possibly but is 5-10mph faster going to be enough to change the tactical situation for the "NEW" P-40 in air combat? Oh yeah, you get an extra 3-5 mph for clipping the wing. 




tomo pauk said:


> .
> We'd trade off some of range to achieve much greater performance.



a couple of hundred pounds isn't going to give you Much greater performance, a little bit yes. This change was thought so valuable by the USAAF that most later versions than the N-1 series had the fuel tank put back in. 


tomo pauk said:


> .
> Never said that R-2600 received no development, but that it never received fighter-plane accessories (ADI, WEP qualification, perhaps a supercharger set for hi-alt work?). I so speak affirmatively about it - hence 'my' P-40



ADI doesn't show up until 1943. Why Wright didn't use it I have no idea, it might have been a god send to B-29 pilots trying to take off with overheating engines form those Pacific Islands. getting event the same take-off power at lower temperatures would have been an advantage. But it does mean greater strain on an engine if used to get more power, I doubt it could be added to much advantage to an "A" series engine. 

WEP only was awarded if the engine proved it could stand up to the power. Given some of the improvements Wright made between the Early engines and the later ones there may be some doubt as the ability of the early engines to use a WEP setting. It is not just a matter of shorter times between overhauls. Breaking a connecting rod or launching a cylinder head through the cowling tends to end a mission pretty quick.
There were a few experimental supercharger set ups and a few very short production runs of turboed early R-2600's. It seems not to have been repeated. Given the troubles with the turboed B-29 engines it might have been a good idea NOT to turbo the R-2600.




tomo pauk said:


> .
> Perhaps some of stuff developed for R-2600 would've ease the R-3360 development?



It might work the other way, I am not sure how much stuff developed for the R-3360 found it's way into later R-2600s.


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## tomo pauk (Apr 7, 2010)

Shortround6 said:


> For now lets stick to 1940. The R-2600 available at this time is the 1600hp for take-off version, the "A" series. It has the Aluminum crankcase. It is good for 1600hp at take-off, 1600hp at 3000ft military power in low gear and 1400hp at11,500ft in high gear.
> For an idea of performance lets look at the P-40 in 1940, two, 50cal guns no armor or self sealing tanks and an Allison engine of 1040 for take off and 1030hp at 14300ft or 1090hp at 13,200ft depending on source (although with 60hp less at 900ft higher they aren't that far apart) at a weight of 6,787lbs gross it manages 357mph at 15,000ft.
> Now for an Idea of what the V-12 engine got for it's 'streamlining' we have the numbers for a Curtiss Hawk 75A-4. Poweerd by a 9 cylinder Wright cyclone of 1200hp for take off and Military ratings of 1200hp at 1800ft and 1000hp at 13,600ft. Speed is 323mph at 15,100ft and 272mph at sea level at a weight of 5,750lbs. again no armor, self sealing tanks but with 4 wing guns crating a bit of drag.
> 
> ...



That would make 8-15 extra mph, making P-40 (from 1940) faster than Spit II Bf-109E-7, the fastest planes in service in second half of 1940. Also much more durable.



> a couple of hundred pounds isn't going to give you Much greater performance, a little bit yes. This change was thought so valuable by the USAAF that most later versions than the N-1 series had the fuel tank put back in.



Okay, the R-2600 was better able to pull it in 1943 with 1750 HP for take off, than Allison with 400 HP less 



> ADI doesn't show up until 1943. Why Wright didn't use it I have no idea, it might have been a god send to B-29 pilots trying to take off with overheating engines form those Pacific Islands. getting event the same take-off power at lower temperatures would have been an advantage. But it does mean greater strain on an engine if used to get more power, I doubt it could be added to much advantage to an "A" series engine.



The more I read about engines, i like ADI more more 



> WEP only was awarded if the engine proved it could stand up to the power. Given some of the improvements Wright made between the Early engines and the later ones there may be some doubt as the ability of the early engines to use a WEP setting. It is not just a matter of shorter times between overhauls. Breaking a connecting rod or launching a cylinder head through the cowling tends to end a mission pretty quick.



Agreed 


> There were a few experimental supercharger set ups and a few very short production runs of turboed early R-2600's. It seems not to have been repeated. Given the troubles with the turboed B-29 engines it might have been a good idea NOT to turbo the R-2600.



No need for turbo here (more so if it was that plagued); USAAC have had two fighter designs with excellent turbo-supercharged engines early enough.



> It might work the other way, I am not sure how much stuff developed for the R-3360 found it's way into later R-2600s.



Yep


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## tomo pauk (Apr 19, 2010)

The FAA planes are my eternal inspiration 
Here is Fulmar again, this time with R-2600 (with 1600 HP, almost 50% more HP for T/O at low level than with Merlin III of Fulmar Mk.I). Sure enough, it would've take a lots of foresight to make it, but it's certainly at my liking. 
On another pic is comparison with Helldiver.


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## tomo pauk (Apr 19, 2010)

A more radical proposal, the Merlin is here supercharged with auxiliary engine of some 300 HP, mounted alt the radiator. Surely, Fairey Battle would've make a good use of it (hopefully).


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## tomo pauk (Apr 19, 2010)

A radical proposal (the Do-355 fans would be thrilled), two Merlins in push-pull layout. It could use some tweaking (we're just added a full ton of metal aft the CoG), like moving the front engine perhaps a foot forward, with some fuel located in the newly acquired sapce, 'thinner' main fuel tank (so the 2nd crew member could move forward to allow 2nd engine being located more towards the CoG), or perhaps an inverted Airacobra layout (engine between main fuel tank navigator, with shaft located under navigator)...
Anyway, here it is (the thin horizontal vertical lines are for 'computing' the aft prop/low fin clearance):


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## tomo pauk (Apr 19, 2010)

Here is how the Fairey Barracuda might have looked like, with a proper engine. R-2800, never the less


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## Marcel (Apr 19, 2010)

G.1 with merlins:


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## tomo pauk (Apr 19, 2010)

Lovely plane indeed


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## tomo pauk (Apr 20, 2010)

The P-51 with a well-streamlined radial; the scale fits to R-2800 Ash-82 (depicted).


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## tomo pauk (Apr 21, 2010)

Fairey Battle in push-pull variant. Mosquito-catcher?
2nd engine is above the place where bomb-aimer originally way in prone position, aux fuel tank and/or bombs would've been there now. Prop shaft under the second crew member (observer/bomb-aimer now, or radar operator in night fighter version), reduction gear afer him.


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## tomo pauk (Apr 23, 2010)

Willy's tandem plane - Bf-110 in push-pull configuration - might have looked this way:


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## hawkeye2an (Apr 23, 2010)

Keep 'em coming Tomo. I look foreward to your new posts. Always something fun to consider.


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## tomo pauk (Apr 24, 2010)

Here are some planes that would've used some extra HP, in master-slave flavor. 
Fw-200, with one slave engine per 2 engines (one per wing), to give it more altitude speed. Note the elongated 'gondola', for better structural integrity.
Second one - Ju-188, with one slave engine per one master engine (BMW-801), only one HMG defensive weapon.


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## tomo pauk (Feb 20, 2011)

Fulmar with 2 Merlins, Beaufighter is for comparison. Hull fuel tank loses lower half (now occupied by guns ammo), new fuel tanks in wings.


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## HBBates (Feb 20, 2011)

Can I offer you one... the French decide to do a post war development on the Ta152c.... reengineer with Bristol Centaurs power egg from the Sea Fury ...
Remove the extension plug at the tail added with the Fw190D to balance out the long nose of the inline.... and a Bristol Centaurs Ta152c looks like a super Fw190A... the fuselage and wing root guns must go so those bays get extra fuel tanks ..... and the out board mg151 gun bay get double up to 2 guns so you back to 4 20mm total


And now for something completely different a He162 seaplane

Because of the high mount engine the He162 is a natural to get made in to a seaplane ...a fighter that can operate off lakes ...and a lake is a runway that can never be bombed out of operation ...
Remove the landing gear and scab on a seaplane hull on the lower fuselage.... think P6M Seamaster like hull .... the guns go up to the wing roots


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## GrauGeist (Feb 20, 2011)

HBBates, because of the size of the He162's wings, you'd probably be better off leaving the cannon in the fuselage...the gunbay can be made isolated from the watertight hull and the ports are far enough foreward, I doubt they'd be an issue regarding water entry...


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## tomo pauk (Apr 8, 2011)

Do 135:
As much of Do-17 airframe as possible, two Jumo 211 (aft engine is behind bomb bay). 2-4 x 20mm, 2 x 30 or 37mm.


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## T Bolt (Apr 8, 2011)

I just love this thread!!


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## tomo pauk (Apr 9, 2011)

Me too


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## Gnomey (Apr 9, 2011)

Interesting stuff! Keep it coming.


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## tomo pauk (Apr 17, 2011)

Thanks for the appreciation 

Fairey Battle with Bristol Hercules; perhaps developed instead of Albacore Barracuda as a carrier torpedo/dive bomber. Dive brakes, later Fairey-Youngman flaps. Exhaust flame suppressors. Extra fuel tanks or MGs in wing bomb cells, if needed. Carb inlet moved to side.


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## Shortround6 (Apr 17, 2011)

What time frame are you thinking of?

For carrier use you need to develop a folding wing. Or leave the planes decked parked. Not something the RN did at the beginning of the war. More fuel isn't really needed, the Battle had pretty good legs as it was, 212 Imp gallons of fuel carried in the wing center section. Beefed up landing gear.

Early Hercules engines were good for about 1375hp for take-off. Trying to match up with the appropriate Merlin is a little difficult. It depends a bit on when the navy planes got 100 octane fuel. You also have to consider that the Hercules has more drag and may use a portion of it's higher power just fighting the drag and not improving the performance of the Airplane. At least one Battle was equipped with a Hercules engine as a test bed aircraft so they probably did have a good idea what the performance was.


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## tomo pauk (Apr 18, 2011)

Ideally it would've been deployed in 1st half of 1940; I reckon it's 1375 HP with 87 oct fuel, and later 1500 with 100 oct (late 1940?). Some 1700 HP for 1944.
We indeed need wing folding, along with stronger landing gear.

Care to share some info about Battle with Hercules? Was it just a test bed for the engine, or some project to upgrade the Battle? 
I've found the pics of the Battle with Taurus (1938 ) and Cyclone (1939?)
The increase of drag would've been noticeable for a clean airframe flying at top speed (provided no power increase), but we need a strong engine to lift a heavy plane from a carrier. Hercules was the best that Brits have had available in the 'dark years'.


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## Shortround6 (Apr 18, 2011)

The Battle was flown with a number of engines, it was big, it was sturdy, it had room in the rear cockpit for test instruments. It was flown with both the Hercules II and XI engines, the Taurus, Fairey's own prince and Monarch engines, Napier Dagger VIII, Napier Sabre I and II, the R-R Exe and 5 different Merlins, all early ones. 
Depending on exactly when in the 'dark years' the Merlin may offer more power than the standard MK III. The MK VIII Merlin used the early Fulmars was good for almost 200hp more than the MK III for take off on 87 octane because it used a different gear ratio to the supercharger. It limited peak altitude performance to 7,500ft instead of 16,250ft like the MK III but it took less power to drive, heated the intake mixture less and allowed the engine to run with the throttle plates more open. 
Switching to a navalised MK X engine would also have boosted take off power from 880 to over 1000hp on 87 octane. Once 100 octane becomes available to the Navy take off power of the Merlins jumps to 1200-1300hp with little more than turning the boost limit adjuster. 
The Battle was a 1934-35 design, time spent modifying it to any great degree would be time spent not working on Barracudas (response to a 1937 requirement) or the Firefly (200 ordered off the drawing board in June of 1940)


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## tomo pauk (Apr 18, 2011)

Hercules was developing 1375 HP (87 oct) in late 1939, Merlin VIII was one year late to achieve 1275 HP (needing 100 oct?). Hercules with 100 oct fuel develops what, 1500 HP? 

I've already stated that such a Sea Battle would've replaced both Albacore Barracuda, so Fairey designers wouldn't be overworked.


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## billswagger (Apr 18, 2011)

tomo pauk said:


> The P-51 with a well-streamlined radial; the scale fits to R-2800 Ash-82 (depicted).


 
i like this rendition, but it makes me think of placing a turbo behind the pilot making leaving the intake originally intended for cooling as an intake for a turbo. 
Performance and weight might dictate the end result. 

Bill


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## tomo pauk (Apr 18, 2011)

A nice (X)P-47J for me, please


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## cherry blossom (Apr 19, 2011)

I feel slightly wicked to distort this thread but were there some planes that should have used their original engines?

For example, the Kawanishi N1K1 Kyōfū floatplane was developed into the N1K1-J Shiden fighter and this later redesigned to give the N1K2-J. One major change was the substitution of the Mitsubishi Kasei of the N1K1 by a Nakajima NK9A Homare 11. However, the Kasei was being developed and the J2M3 Raiden, which was roughly a contemporary of the N1K1-J Shiden, had a Kasei 23a engine which may have given 1580 hp at 5500m at 2500 rpm compared to 1460hp at 5700m at 2900 rpm for the Homare 11 (data from here ). The Kasei was easier to maintain and possibly more reliable. Not changing the engine might have freed up enough designers to prepare a low wing aircraft which might not have had problems with its undercarriage. 

If the Kasei, was judged not to have development potential, could Kawanishi have shoehorned in a 54l Mitsubishi Ha 104 (? Ha. 42 or MK6 or MK10 ?) giving perhaps 1610 hp at 6100m in its 1944 version. The diameter had gone from the Kasei's 1.34 m to 1.372 m but they might have looked at a Fw190 since they designed the Kyōfū. The extra weight of that engine might have been a problem but the development potential was greater. Unfortunately, I don't think that the smaller MK9 series was available.


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## cherry blossom (Apr 19, 2011)

tomo pauk said:


> How might have looked the Romanian 400mph + fighter: IAR-80 hull mated with engine salvaged from P-38J, along with four .05cals. Radiator copied from Hurricane. Supercharger between engine and windscreen.
> Empty weight circa 2000-2200 kg propelled by 1425 HP - the ultimate lightweight fighter.


 
As I cannot compete with the Photoshop work, I will risk Shortround's comments by asking how its performance would compare with an IAR-80 re-engined with a Gnome-Rhone 14R taken from a MB-157


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## Shortround6 (Apr 20, 2011)

1st, the IAR-80 with a salvaged P-38J engine would have been quite a trick. The P-38J powerplant installation went to about 3168lbs (1440kg) not including the fuel system (tanks and piping) even from 2200kg that doesn't leave much weight for the rest of the airplane. 

2nd, the Gnome-Rhone 14R seems to be a bit of a phantom engine. The post war engines never seemed to match the pre/early-war claims for power at altitude. The pre/early war claims of 1700hp at 26,000ft must be viewed with skepticism .
It also weighed about 200kg more than the 14N and would need a larger oil cooler and propeller.
Better performing yes, but how much better?


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## cherry blossom (Apr 20, 2011)

I agree that there is something suspicious about the claimed power of the 14R and the performance of the MB-157. I should also mention that my suggestion was not original as it is at Axis History Forum • View topic - Review: "IAR-80" Story of the Romanian fighter


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## tomo pauk (May 1, 2011)

Ditching the Kingcobra Airacomet, a jet-powered plane is built instead. 4 x .50cals (jet is still weak), enlarged cooling intakes now feed the jet engine.


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## wuzak (Aug 13, 2011)

tomo pauk said:


> How might have looked the Romanian 400mph + fighter: IAR-80 hull mated with engine salvaged from P-38J, along with four .05cals. Radiator copied from Hurricane. Supercharger between engine and windscreen.
> 
> Empty weight circa 2000-2200 kg propelled by 1425 HP - the ultimate lightweight fighter.




While using captured engines would be clever in one sense, it obviously has problems in terms of supply, spares and servicing.

For me the long nose of the IAR-80 beckoned for the installation of a Daimler Benz DB605 or 603 with annular radiator. Apparently a prototype was fitted with a Jumo 211 with annular raditor - maybe the Jumo 213 would have been an option.


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## tyrodtom (Aug 13, 2011)

I wonder what the heat waves coming off that turbo right in front of the windscreen would do to the pilots forward visibility. Any night flying would be out of the question.
Come to think of it, that's where the turbos exhaust is also, they'd never have to worry about the windscreen icing over.


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## wuzak (Aug 13, 2011)

tyrodtom said:


> I wonder what the heat waves coming off that turbo right in front of the windscreen would do to the pilots forward visibility. Any night flying would be out of the question.


 
Not to mention the pilot's comfort levels with that heat in front of him.


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## wuzak (Oct 11, 2011)

A Vulture powered Corsair


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## wuzak (Oct 11, 2011)

tomo pauk said:


> The P-51 with a well-streamlined radial; the scale fits to R-2800 Ash-82 (depicted).



The height of the engine looks OK, but what about the width? The Mustang's fusealge is not much more than 30" wide - and the radial with cowling is going to be 55"+.


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## wuzak (Oct 11, 2011)

As posted before, Griffon powered Lightning


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## tomo pauk (Oct 12, 2011)

wuzak said:


> The height of the engine looks OK, but what about the width? The Mustang's fusealge is not much more than 30" wide - and the radial with cowling is going to be 55"+.



The NAA will have to do what Lavotchkin Kawasaki did while re-engining their fighters


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## wuzak (Oct 12, 2011)

tomo pauk said:


> The NAA will have to do what Lavotchkin Kawasaki did while re-engining their fighters



Rebuild the fuselage?


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## tomo pauk (Oct 12, 2011)

Think they attached different engine mount and added 'skirts' to blend the engine cowling with the hull?


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## brewerjerry (Oct 12, 2011)

tomo pauk said:


> Sure, here 'tis
> (Damn, those wings are thin - guess we have add some jet engines in place of piston engines)



Hi
If you get the time, any chance of a side view/profile of the taurus whirlwind in post 13 ?
cheers
Jerry


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## Shortround6 (Oct 13, 2011)

And the advantages of a Taurus powered Whirlwind are?

More drag

more power for take off and low level work

little or no additional power at 15,000ft or so

An engine that may have had as many problems as the Peregrine


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## wuzak (Oct 13, 2011)

Shortround6 said:


> And the advantages of a Taurus powered Whirlwind are?
> 
> More drag
> 
> ...



An engine that suffered from chronic overheating, from what I understand.

And one that wasn't going anywhere while Bristol were sorting Hercules production out (a la Peregrine and Vulture et al for Rolls-Royce).


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## tomo pauk (Oct 13, 2011)

Shortround6 said:


> And the advantages of a Taurus powered Whirlwind are?
> 
> More drag
> 
> ...



Taurus-engined Gloster F.9/37 was achieving 30mph more than Peregrine-engined one, so that should account for something. Deletion of glycol radiators enables as twice as much of internal fuel. One engine type less (reduces logistics footprint RAF others that could use it). 

Anyway, Twin Wasp is my preferred engine for both Whirly F.9/37.


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## Shortround6 (Oct 13, 2011)

Taurus-engined Gloster F.9/37 used a pair of prototype engines that never saw service. Wasn't it later re-engined with Taurus III engines which dropped it's speed by about 30mph? All service Taurus engines seem to have had a FTH of about 3,500 hundred feet. 

Taurus engine was about 1300lbs, Twin Wasp is about 1450lbs, Peregrine was about 1140lbs without radiators which could be mounted on or slightly behind the center of gravity.


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## tomo pauk (Oct 13, 2011)

Perhaps it was the Taurus III at 900 HP, but Taurus II (1940, for Beaufort I) was rated at 1080 HP?


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## Shortround6 (Oct 13, 2011)

The later Taurus ( VI, VII, XVI ) engines seem to be rated at 1130hp at 3100rpm using 4.75lbs boost at 3,500ft. even on 100/130 fuel, they may have done nothing more than check to see if the fuel fouled the plugs more than 87 grade. If you loose 2% per 1000ft of altitude then these engines would be good for about 870hp at 15,000ft. Great engines (maybe?) for a low altitude attack plane, not so good for a fighter expected to do much of anything even at 15,000ft. If you regear the supercharger to raise the FTH you lose some of the low altitude power. Bristol never really put any more development into the engine and it was troublesome enough that not only Australia power it's Beaufort's with Twin Wasps ( more of a supply issue though) but the British made plans to do so also. Ship carrying the first shipment of engines was torpedoed however. 164 British built planes did wind up with Twin Wasps however.


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## tomo pauk (Oct 13, 2011)

So we have basically two 'paths' for a 'Taurused' Whirly.
One is that engines stay as they were. Such a plane can do tank busting/CAS (in lieu of Hurri II-IV, and (not tank busting) later Blenheims ), anti-shipping job (perhaps not by a torpedo, but with bombs), long range fighter sweeps (but not vs. France/Low countries under LW control), .
With re-geared engines, it can be almost as competitive as Typhoon, perhaps?

As for Taurus being being troublesome, that is clear to all of us


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## nuuumannn (Oct 17, 2011)

tomo pauk said:


> How might have looked Ki-61 with front end of an captured P-40 and clipped wings, HMGs relocated in wings. Perhaps 600-630 km/h - depending on Allison - and comparable with Hellcat Spit Mk.V.



How about Ki-61 with Meredith Effect radiator installation (a la P-51 Mustang; buried in fuse with underneath airscoop)? Maybe a Ki-61D?


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## tomo pauk (Oct 17, 2011)

Original Ki-61 almost 'had' the radiator harvesting Meredith effect; really a 300-400 more HP (with inline, or 500-600 with radial) was needed by 1944 for the plane to remain competitive.


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## nuuumannn (Oct 17, 2011)

tomo pauk said:


> Original Ki-61 almost 'had' the radiator harvesting Meredith effect; really a 300-400 more HP (with inline, or 500-600 with radial) was needed by 1944 for the plane to remain competitive.



There was no plenum chamber area, so in its production state it did not. I'm not arguing whther it remained competitive or not, just what it would look like with a Meredith effect radiator installation and perhaps a better inline engine. Isn't that what this thread is about? A little fantastic indulgence?


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## tomo pauk (Oct 18, 2011)

No need to get upset


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## nuuumannn (Oct 18, 2011)

tomo pauk said:


> No need to get upset



Okay, point taken Was going to say the same to you too

So, seriously now, where's my picture?


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## rank amateur (Sep 17, 2014)

I'm still waiting actually..


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## Ivan1GFP (Sep 18, 2014)

How about a Kawasaki Ki-61-II with a Daimler Benz DB605D from a Me 109K?

Forget that logistically this never would have worked, but here we would have a nice slick airframe with enough engine power to kill just about anything on the Allied side in the Pacific.
The engine installation should be very easy assuming an adequate supply of engines....
....and good consumables such as fuel, spark plugs, etc.

- Ivan.


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## Ivan1GFP (Sep 18, 2014)

Regarding the rather long discussion revolving around the Wright R-2600 engine and how it was never installed in a fighter:
Remember the prototype Grumman Hellcat used a R-2600 which didn't offer enough performance and was promply replaced with the P&W R-2800.

- Ivan.


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## merlin (Sep 19, 2014)

I can't remember what forum it was on - but I have seen a photo of a Beaufighter (Australian I think) with R-2600 engines - looked quite good.

Gloster F.5/34 prototype flew with 840 hp Mercury - which would be the best option 
- (A) more powerful Mercury XV 905 hp (as per Blenheim IV), and Mercury 30 950 hp (as per Blenheim V; or
- (B) R-1830 Twin-Wasp higher power; or,
- (C) Bristol Taurus a narrower engine, but although better than the Mercury in output reliability might be in question; or the French option
- (D) Gnome-Rhone 14N - initially at 970 hp then went up I believe to 1,080 hp


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## razor1uk (Sep 19, 2014)

Some very nice alternative concept blueprint arts, but I wonder if anyone has made this suggestion...
Could all the created/edited or fictional arts should be tagged as such to prevent future mis-identification of these creations as real aircraft concepts/blueprints/sideviews etc, as some of them seem to keep only one of their orignal model identification designations/names/numbers.

Who would know any different if in 50+ years technological changes and or a calamity(../ies) meant that only a portion of remaining data was the fictions in this thread; unlikely as it maybe, no one can predict that far what will happen apart from many what could happen.

Just a thought.


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## tomo pauk (Sep 19, 2014)

Ivan1GFP said:


> Regarding the rather long discussion revolving around the Wright R-2600 engine and how it was never installed in a fighter:
> Remember the prototype Grumman Hellcat used a R-2600 which didn't offer enough performance and was promply replaced with the P&W R-2800.
> 
> - Ivan.



The R-2600 that powered 1st Hellcat have had several thing going against it. 1st will be that, even as a 2-stage engine version, was to power a 6-7 ton fighter. No can do with 1700 HP, at least not satisfactory. 2nd would ne that, even as the 'plain vanilla' R-2600 was developed earlier than similar R-2800, Pratt Whitney have probably had a lead in a development of 2-stage superchargers. 
For a fighter to make sense to be powered with R-2600, it need to use early military version 1st (1600 HP for TO), then switch to 1750 HP version from early 1941 on. Need to be deployed, say, from late 1940 in RAF CW units, and then, as availability allows, in different US fighter units. The fighter also need to be reasonably small (220-270 sq ft, depending whether we talk about land- or CV-based A/C - hence my drumming of the P-36/40 with that engine), and not to have 300-340 sq ft wing like Hellcat and Corsair have had.



merlin said:


> I can't remember what forum it was on - but I have seen a photo of a Beaufighter (Australian I think) with R-2600 engines - looked quite good.
> 
> Gloster F.5/34 prototype flew with 840 hp Mercury - which would be the best option
> - (A) more powerful Mercury XV 905 hp (as per Blenheim IV), and Mercury 30 950 hp (as per Blenheim V; or
> ...



G&R version would look fine for, say, Poland, if they can get that before war started. For the British, the Taurus, for CW license production Twin Wasp. Maybe also the Cyclone?


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## swampyankee (Sep 19, 2014)

Colin1 said:


> What are the net benefits
> of using a third powerplant to act as a supercharger for the two existing units?
> I can't see the weight of even two supercharger assemblies approaching the weight of a powerplant and what effect will the third unit be having on fuel consumption/range?



I'll bet controlling the relationship between the propulsion engines' demand for air and the compressor-engine set's supply of air was easy to solve. And, of course, it would be absolutely easy-peasy to have low-loss, leak-free ductwork connecting the engines to the compressor. 

Neglecting that, I think that the benefits of having a dedicated engine driving a compressor to be shared among all the propulsion engines is shown by the number of aircraft produced using that scheme. Leaving aside the fact that it's a single point of failure, the dedicated engine/compressor set and its required ductwork is going to be heavy and take up a lot of volume, probably heavier than individual engine-driven compressors, and certainly taking up much more volume in the wings and fuselage. 

In any case, if I really wanted an ultra-high altitude, piston-engined aircraft, one could use two-stage turbocharging. Indeed, there is a modern project for an ultra-high altitude aircraft which uses a three-stage turbocharger, NASA's Perseus B (NASA Armstrong Fact Sheet: Perseus B Remotely Piloted Aircraft | NASA).


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## Ivan1GFP (Sep 19, 2014)

tomo pauk said:


> The R-2600 that powered 1st Hellcat have had several thing going against it. 1st will be that, even as a 2-stage engine version, was to power a 6-7 ton fighter. No can do with 1700 HP, at least not satisfactory. 2nd would ne that, even as the 'plain vanilla' R-2600 was developed earlier than similar R-2800, Pratt Whitney have probably had a lead in a development of 2-stage superchargers.
> For a fighter to make sense to be powered with R-2600, it need to use early military version 1st (1600 HP for TO), then switch to 1750 HP version from early 1941 on. Need to be deployed, say, from late 1940 in RAF CW units, and then, as availability allows, in different US fighter units. The fighter also need to be reasonably small (220-270 sq ft, depending whether we talk about land- or CV-based A/C - hence my drumming of the P-36/40 with that engine), and not to have 300-340 sq ft wing like Hellcat and Corsair have had.



So if I understand you correctly: The R-2600 with a Military Rating of 1700 HP is insufficient to power a big fighter like the Hellcat, but the R-2800 with a Military Rating of 1800 HP (from the Pilot's Manual) is quite suitable?

Keep in mind that aircraft are very seldom designed without a requirement. The US military didn't believe in minimalist aircraft. They had specifically gone away from the radial engined P-36 to the P-40 series to get the improved aerodynamics of an inline. The inline installation was significantly heavier but they were willing to sacrifice climb and maneuverability to get just a bit of extra speed. I don't see the Army ever agreeing to go back to the equivalent of a P-36 with a bigger engine.

The Navy even with the Wildcat wanted good altitude performance even if the battles were happening at low altitude which is why they kept using the R-1830 instead of the R-1820 engines until the FM-2 which was never considered a first line fighter. This is certainly a rehash of the earlier conversation, but the R-2600 never had that altitude performance.

- Ivan.


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## wuzak (Sep 19, 2014)

Ivan1GFP said:


> Keep in mind that aircraft are very seldom designed without a requirement. The US military didn't believe in minimalist aircraft. They had specifically gone away from the radial engined P-36 to the P-40 series to get the improved aerodynamics of an inline. The inline installation was significantly heavier but they were willing to sacrifice climb and maneuverability to get just a bit of extra speed. I don't see the Army ever agreeing to go back to the equivalent of a P-36 with a bigger engine.



Don't think they lost anything in climb with the P-40 compared to the P-36.


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## Shortround6 (Sep 19, 2014)

The 1st problem with the R-2600 was that was actually slightly larger in diameter than the R-2800. Not enough that you could pick up the difference in a photo of the plane using the engine but it was there. 

Wiki; " The Cyclone-powered XF6F-1 (02981) first flew on 26 June 1942," 

By which time P&W had built about 120 two stage *2000hp* R-2800s and about 2200 single stage *2000hp* R-2800s, this doesn't count Ford. 

The " just a bit of extra speed" was more like 30-40mph by the time they were done. Of course they then added all kinds of 'stuff' to the P-40 and slowed it down again but try adding the same amount of "stuff" to a P-36 and see what happens 

One reason the Wildcat could go to the Cyclone in the FM-2 was that not only did it have 100-150 more HP for take-off than the Twin Wasp but they were running the new engine 100rpm (and 200 rpm for take-off) faster than the old Cyclones _AND_ had a *NEW* supercharger. The FM-2 Wildcat engine could give 1000hp at 17,000ft compared to the older Cyclone giving 1000hp at 13,500ft. It kind of split the difference in altitude performance between the old Cyclone and the Two stage R-1830 while weighing about 150lbs less and that doesn't include the inter coolers or ducting.


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## rinkol (Sep 19, 2014)

For some reason, the mass produced versions R-2600 fell short in rated altitude, even in comparison with foreign engines, such as the BMW 801, which also used a single stage supercharger. There was one version with a turbosupercharger, but this seems to have been unsuccessful.

Aside from this, the R-2600 probably had more faults than the R-2800 if the following link is anything to go by

http://www.enginehistory.org/Wright/R-2600/R-2600CaseHx.shtml


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## rinkol (Sep 19, 2014)

duplicate post


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## Lefa (Sep 20, 2014)

MÃ¶rkÃ¶-Morane, the Finnish Frankenplane - Passed to Development - War Thunder - Official Forum

The Finnish attempt to improve the old plane performance.


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## merlin (Sep 20, 2014)

tomo pauk said:


> Re: Gloster f.5/34
> 
> G&R version would look fine for, say, Poland, if they can get that before war started. For the British, the Taurus, for CW license production Twin Wasp. Maybe also the Cyclone?



If the prototype is built earlier, Countries that already license produce the Mercury may be interested e.g. Sweden Finland, Poland is interesting - P11c had a Mercury (earlier version), the PZL P.50 was to have the 840 hp Mercury, whilst the P.24 had the Gnome-Rhone 14N.

Which brings an interesting image of the Luftwaffe facing not P.24s but Polish Gloster monoplane fighters - they'll still get beat, but they'll take a few more with them, and they may be more readily accepted by the RAF !!


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## tomo pauk (Sep 20, 2014)

Ivan1GFP said:


> So if I understand you correctly: The R-2600 with a Military Rating of 1700 HP is insufficient to power a big fighter like the Hellcat, but the R-2800 with a Military Rating of 1800 HP (from the Pilot's Manual) is quite suitable?



Military and take off power was 2000 HP for Hellcat's R-2800, at really low altitudes. Same regimes for the R-2600: 1750 HP; maybe it was only 1700 for the 2-stage version used on 1st Hellcat? 



> Keep in mind that aircraft are very seldom designed without a requirement. The US military didn't believe in minimalist aircraft. They had specifically gone away from the radial engined P-36 to the P-40 series to get the improved aerodynamics of an inline. The inline installation was significantly heavier but they were willing to sacrifice climb and maneuverability to get just a bit of extra speed. I don't see the Army ever agreeing to go back to the equivalent of a P-36 with a bigger engine.



The Army fighter 'contest' of 1939 included several radial-engined fighters too, specifically from Seversky. P-40 won, because it offered the best performance (combined with availability for the Army to have plenty of those in reasonable time), not because it was powered by an V-12.



> The Navy even with the Wildcat wanted good altitude performance even if the battles were happening at low altitude which is why they kept using the R-1830 instead of the R-1820 engines until the FM-2 which was never considered a first line fighter. This is certainly a rehash of the earlier conversation, but the R-2600 never had that altitude performance.
> 
> - Ivan.



The R-2600 certainly did not have had that great hi-alt performance, but then it was vastly better under 15000 ft; some 30% greater under 12000 ft. Above 18-19000 ft, it was still offering some 10% more power than a two stage R-1830, and it was considerably more powerful than a single-stage R-1830 that a good number of F4Fs got.



rinkol said:


> For some reason, the mass produced versions R-2600 fell short in rated altitude, even in comparison with foreign engines, such as the BMW 801, which also used a single stage supercharger. There was one version with a turbosupercharger, but this seems to have been unsuccessful.



The main culprit for non-stellar hi-alt performace probably lays in it's small supercharger - 11 in diameter, vs. 13 in for the BMW-801 and Hercules; some Hercules engines have had 12 in S/C installed. Other thing was it's RPM, 2600 vs BMW's 2700 and Hercules with 2800 RPM. 
We can also note that advantage the BMW-801C* (and the restricted 801D?) possessed against the R-2600-13 was some 50 HP at 15100 ft - 1361 HP (1380 PS) vs 1310. BMW installation was a more streamlined affair, though, with a better layout of exhaust stacks. The duration of that power was 3 min for the BMW, vs. 5 for the R-2600. 

*max RPM was only 2550 in second S/C gear? 



> Aside from this, the R-2600 probably had more faults than the R-2800 if the following link is anything to go by
> 
> R-2600 Case History



Yep, too bad some people didn't ended in jail, or worse.


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## Shortround6 (Sep 20, 2014)

A few things to consider about the R-2600.
Cooling of air cooled engines was not as well understood in the mid/late 30s as it was just a few years later. Things changed rapidly. The R-2600 may have been designed as much for commercial transport use as for military (especially fighter) use. The Army sure wasn't buying very much of _anything_ from 1936 until the Spring of 1939. The R-2600 was in low level production in March of 1938, over a year before the the Army 1939 fighter trials. First use was the Boeing 314 Flying boat. Max power at sea level and a few thousand ft was much more important than high altitude performance. The smallest supercharger that will give the needed boost at sea level (or low altitude airports) means more power to the propeller for the same power generated in the cylinders. 
Power generated in the cylinders governs the cooling load/problem. Also the weight/strength of the engine to handle the loads. 
P W started later and P W didn't like _big_ cylinders after they got burned, literally, with the Hornet "B" 9 cylinder engine (R-1860), which had cooling problems including melted pistons. Smaller cylinders offer better cooling because there is more cylinder wall per unit of volume. 
The AAC (Army Air Corp) thought air cooled engines wouldn't work for turbo-charged high altitude bombers and while they were proven wrong it took a lot of work with finning and baffling. 
And here you hit one of the snags with the R-2600 as a fighter engine. It is about the same diameter as a Cyclone 9 or at least much closer than the the R-1830 so that is a better starting point. Then we have the cooling problem.







Granted this is just a single case but please note that for a 1600hp engine the thermal losses are worth 1020hp. Basically going from a 1200hp engine to a 1600hp engine means you have 33% more heat to get rid of and you need 33% more airflow though the cowl or radiators or oil coolers. Some of your extra power is going to the extra cooling drag, certainly not all and you are going to see a performance increase, just not as much as the 33% increase in power implies. Also please note that 140hp to drive the supercharger for a 1600hp engine is on the low side. Using a higher gear ratio to improve altitude performance means more power to the supercharger and less to the propeller percentage wise but changes the cooling load hardly at all. 

Using two-stage superchargers or turbos makes thing even worse at high altitudes. In the original engine (single speed or two speed) the power falls off with altitude as not as much fuel/air is being burned in the cylinders. Of course the thinner air doesn't cool as well either even though it is colder for a bigger temp difference. Going to a two stage supercharger raises the power needed to drive the supercharger/s you get more to the prop at the higher altitudes but you have raised the heat load, can the original cooling system (and on an air cooled engine a large part of that is the number/shape/size of the fins) handle this higher load in the thin air? You also have the problem of the higher intake charge temperature. Temperature of the intake charge flows through the engine, raise the intake temperature by 100 degrees and the exhaust temperature will be about 100 degrees hotter as will the temperature anywhere in-between including the combustion chamber. Those fins that worked just fine at 3,000ft and 70 degrees temperature may not handle the load at 23,000ft and 100+ intake temperature inspite of the much cooler air (you have roughly 1/2 the mass of air passing the fins). The Turbo adds a bit to the problem in that the exhaust is slightly restricted and the exhaust valve/seat/guide area may run a bit hotter. 
ALL of these problems _can_ be cured but it often took new head casting/forging/machining operations, new cylinder barrel fins, new baffles, etc. which all took time to design and try out and find the best (cheapest and quickest) answer. Please note that Wright redesigned the entire engine to get the 1900hp 'version' which was hardly cheap or quick

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## tomo pauk (Sep 21, 2014)

Another take on one of the inspirations here, namely the P-38: the nightfighter, with two turbocharged R-1830s. The radios radar (re)located in the booms, approx. at the area once the Prestone coolers were - in order to compensate for that lost weight. Second crew member, hopefully in a more neat accommodation than as it was with the P-38M. Northrop gets to build these? Not a 400 mph nightfighter, but it should be good for 380 - a bit faster than the Black Widow?


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## Shortround6 (Sep 21, 2014)

The R-2600 was a good bomber or transport engine as it was designed to give good power for weight at low altitude. The early versions were rated variously on 90-91 or 95 octane fuels and with the coming of 100 octane (american) the allowable power did *NOT* go up. This may be a clue 
Many of the early versions used single speed superchargers with _very_ low critical altitudes. Think Merlin VIII
What did happen was that the critical altitude improved, better fuel allowed for more compression in the supercharger compared to outside air but max boost held the same. 
The GR-2600-A-2B using 91 0ctane and a blower ratio of 7.0:1 was rated at 1600hp for take-off, 1600hp Military at 1500ft (yes 1500ft) and max continuous of 1350hp at 5800ft.
The GR-2600-A-2A using 100 0ctane and a blower ratio of 7.0:1 was rated at 1600hp for take-off, 1600hp Military at 1500ft (yes 1500ft) and max continuous of 1350hp at 6200ft.

Adding the two speed drive helped things out a bit.
The GR-2600-A-5B using 91 0ctane and a blower ratio of 7.14:1 was rated at 1600hp for take-off, 1600hp Military at 1000ft (*yes 1000ft*) and max continuous of 1350hp at 5000ft. Using the 10.0:1 high gear gave 1400hp Military at 10,000ft and 1275hp max continuous at 11500ft.
The GR-2600-A-5B using 100 0ctane and a blower ratio of 7.14:1 was rated at 1600hp for take-off, 1600hp Military at 1500ft (back to 1500ft) and max continuous of 1350 hp at 5000ft. Using the 10.0:1 high gear gave 1400hp Military at 11,500ft and 1275hp max continuous at 12,000ft.

Wright had started work on an improved R-2600 (the 1700hp version) in 1938 but it would not run until Nov 1939 and entered production in June of 1941, Only 441 were built in 1941. This has much better prospects as a fighter engine but is a bit late in timing as it comes _between_ The P W R-2800 A rated at 1500hp Military at 14,000ft and the R-2800 B rated at 1600hp Military at 13,500ft. 

The GR-2600-B2 using 100 0ctane and a blower ratio of 7.06:1 was rated at 1700hp for take-off, 1700hp Military at 4100ft (yes 4100ft) and max continuous of 1500 hp at 6,700ft. Using the 10.02:1 high gear gave 1450hp Military at 14,100ft and 1350hp max continuous at 15,000ft.

.


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## Shortround6 (Sep 21, 2014)

tomo pauk said:


> Another take on one of the inspirations here, namely the P-38: the nightfighter, with two turbocharged R-1830s. The radios radar (re)located in the booms, approx. at the area once the Prestone coolers were - in order to compensate for that lost weight. Second crew member, hopefully in a more neat accommodation than as it was with the P-38M. Northrop gets to build these? Not a 400 mph nightfighter, but it should be good for 380 - a bit faster than the Black Widow?



http://zenoswarbirdvideos.com/Images/B-24/B24OL.gif

This one is a real can of worms. SOOOO much depends on the drag of the R-1830 installation. Throw in the fact that the R-1830 _ONLY_ exceeds 1200hp per engine at some point in 1943 in prototype aircraft (although a higher critical altitude for 1200hp was achieved earlier.) The R-1830 _eventually_ hit 1350hp at 30,000ft in the B-24*N* production version. Please note there is *NO* WEP rating. 1350hp from sea level to 30,000ft. By the time the R-1830 gets to 1350hp the Allison is giving 1600hp WEP. I have no idea how big the inter-coolers on the B-24 were. 

One of about 10-12 planes with the 1350hp turbo R-1830;






As for replacing the P-61? The radar used in the P-61 weighed about twice as much as the radar used in the P-38. It had about twice the range depending on target and it could search a 180 degree arc vs the 120 degree cone of the P-38 radar. 

Picture of P-61 radar antenna:






One reason the 20mm cannon were in the belly of the the P-61 with that pregnant look


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## tomo pauk (Sep 22, 2014)

> Shortround6 said:
> 
> 
> > http://zenoswarbirdvideos.com/Images/B-24/B24OL.gif
> ...


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## GrauGeist (Sep 22, 2014)

The SCR-720A radar system used in the P-61 was not only heavy as mentioned, but was also large in size. You would have to modify the fuselage quite a bit in order to fit that antenna assembly in the nose.

After all the modifications and refitting, you'd probably end up with something that looked alot like the XP-58


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## tomo pauk (Sep 22, 2014)

Hopefully not 

Here is the 'Swordfish', FWIW (from Wikipedia):







vs. plain vanilla P-38 (from mustangsmustangs.com):


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## Elmas (Sep 22, 2014)

But there's a reason if engines designed about early-mid thirties gave the maximum power at low levels. As stated before they were designed for _both civil and military _ use, so the flight level of airplanes could not exceed much more than ten thousand feet. No pressurised airframes and unpractical to make the passengers of a liner to breath pure oxigen....


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## Shortround6 (Sep 22, 2014)

tomo pauk said:


> > Thanks for the link to the table rest of the stuff you've contributed here
> > The Japanese were able to make the Ki-45 going 357 mph at 18500 ft, on 2 x 960 HP. The wing area was some 10% greater than of the P-38, but the Ki-45 was significantly lighter.
> > I was not 'aiming' on the 1350 HP variant of the R-1830, but the 'usual' 1200 HP one. There is no doubt that a V-1710 powered version would've been faster.
> 
> ...


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## GrauGeist (Sep 22, 2014)

Here's a couple "glass nosed" P-38s...

The first one was actually built for bombing (P-38J-15-LO 'Colorado Belle', 1943-1945), the second P-38 pictured was modified for civil land surveying.

The fuselage for the P-38 was actually quite small and an adaptation to fit such a large radar in it would require extensive work like I mentioned. And once the fuselage was been modified to shoe-horn the radar system in, where would the weapons go?


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## tomo pauk (Sep 22, 2014)

Shortround6 said:


> Ki-45??
> Or Ki-46?



Ki-45, at least going by this table.http://www.wwiiaircraftperformance.org/japan/japfighters-comp.jpg OTOH, Wikipedia gives only 336 mph. 



> The problem, given even a slightly larger fuselage, isn't so much the space (cubic feet) occupied by the black boxes but the size of the radar antenna and radar dome. That parabolic dish in the photo in 29" (74cm) across and rotates 90 degrees to either side, 20 degrees down and 50 degrees up. and does several hundred times per minute in scan mode.
> The earlier SCR 520 radar used in the P-70 was bulkier and heavier and there is part of the problem with using the "retrospectroscope"
> 
> You KNOW what the size of the finished radar units will be. When work started on the night fighters they had no idea how big/heavy the radars of the future (2-3 years down the road) would be. They might get smaller (they did) they may get longer ranged ( they did) but how much smaller for what range? or would a slightly bigger unit give even more range?



We know that RAF fighters were using bow arrow antennae as early as in 1940. Granted, not as good solution as the late war stuff, but it shows that useful NF, with useful radar can be built much earlier than P-61. 
Once the P-38 NF is in production (winter of 1942/43?), we can go for bigger 'badder' stuff.



GrauGeist said:


> Here's a couple "glass nosed" P-38s...
> 
> The first one was actually built for bombing (P-38J-15-LO 'Colorado Belle', 1943-1945), the second P-38 pictured was modified for civil land surveying.
> 
> The fuselage for the P-38 was actually quite small and an adaptation to fit such a large radar in it would require extensive work like I mentioned. And once the fuselage was been modified to shoe-horn the radar system in, where would the weapons go?



'Swordfish' featured the accommodation for two, in a longer and overall bigger nacelle.


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## GrauGeist (Sep 22, 2014)

tomo pauk said:


> 'Swordfish' featured the accommodation for two, in a longer and overall bigger nacelle.


This is true, the fuselage was "bigger" in the fact that it was lengthened. The radar system used, was a fixed antenna unlike the SCR-720, which was an articulated or "sweeping" type. To place the SCR-720 system in the P-38, you would have to increase the height of the fuselage and widen it, to the same dimensions the P-61 and the A-20 used for their installations.

You'll note that the P-38 nightfighter had a under-nose mounted radar assembly while retaining their upper nose armament, but in a situation where a SCR-720 is stuffed into a heavily modified P-38, you'll have to consider not only relocating the armament, but make the radar mount sufficient far enough forward to clear the nose-gear assembly.

After all that work, you'll end up with something that looks alot like this!


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## Shortround6 (Sep 22, 2014)

The thing is to be built by Northrop, _instead_ of the P-61, it has to do what the P-61 was supposed to do. The US was fooling about with A-20s as night fighters (P-70s).

Douglas P-70 Nighthawk

and although not spelled out, even more different radar fits were used than are mentioned in this article. Even the A-20 resorted to belly packs of guns in order to fit in some of the different radar types. Or to preserve pilots night vision  

If you have trouble putting certain models of radar inside an A-20 the the P-38 doesn't offer much hope. The later P-38s may have been moderately successful but carried a much lower capability radar than the P-61.


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## Nivek (Jul 15, 2017)

P-36 with R-2600


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## Shortround6 (Jul 15, 2017)

Maybe I am missing something but it looks like you are mounting an engine that weighs 535lbs more than a P-36 engine roughly 6in further forward than the existing engine? 
Seems like a lot of faith is being placed on the longer, larger rear fuselage to balance things out?
I would note that lowering the thrust line by 3.5 inches might not be the best idea either unless longer landing gear is used to regain prop clearance. And longer landing gear pushes the wheel/tires further to the rear of the wing into a thinner part. Bulges over the wheel wells?

This also assumes you can get a prop with a similar diameter to absorb the extra power. Douglas A-20 uses an 11ft 3in prop for their R-2600 engines.


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## GregP (Jul 22, 2017)

How about a Reggiane Re.2005 with an R-2800 out of a Corsair?






Lots more power, and reliable. 500 more pounds, but farther back on the airframe.


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## swampyankee (Jul 22, 2017)

It's probably easier to re-engine with engines out on the wings -- there were prototypes of the B-17 with Allison V-12s and of the B-29 with Allison W-24s, and there were production Lancasters, Beaufighters, and Halifaxes built with both Merlins (the majority) and Hercules. 

Sources
British WW2 Bomber Aircraft (1939-1945)


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## Nivek (Jul 22, 2017)

Shortround6 said:


> Maybe I am missing something but it looks like you are mounting an engine that weighs 535lbs more than a P-36 engine roughly 6in further forward than the existing engine?
> Seems like a lot of faith is being placed on the longer, larger rear fuselage to balance things out?
> I would note that lowering the thrust line by 3.5 inches might not be the best idea either unless longer landing gear is used to regain prop clearance. And longer landing gear pushes the wheel/tires further to the rear of the wing into a thinner part. Bulges over the wheel wells?
> 
> This also assumes you can get a prop with a similar diameter to absorb the extra power. Douglas A-20 uses an 11ft 3in prop for their R-2600 engines.



Those are good points. My thoughts: The R-2600 is about 7" larger diameter and I wanted to keep the pilot to top of engine cowl relationship the same. So the engine thrust line is lower than the thrust line of the R-1830 while the top of the engine is about the same place. I used the firewall as a base line for engine installation and the R-2600 is about 3 inches longer than the R-1830. The larger engine will most likely need a larger propeller hub so the front of the engine from the firewall is about 3-6 " farther out. To compensate for the increased front weight I added structure to the rear of the fuselage by increasing its vertical cross section and lengthening the fuselage as much as might be necessary. I think this would also clean up the airflow on the bottom of the fuselage. I don't know how much that would be so I just guessed at a minimum of 12 inches. Moving the battery and radio farther aft along with increasing the strength and weight of the rear fuselage may be enough? ....I supposed more length could be added as necessary.

The length of the prop may need to be a little longer if the increase power cannot be utilized by changing the design of the propeller width/cord. The wing has a cord that could be lengthened to the rear as it extends farther out from the fuselage. This would allow for an increase in landing gear length. Also this would add a little weight to the rear of the center of gravity. It also would increase the wing area a little. This would minimize the wing loading change with the added weight.

But as someone said, The R-2600 had early development issues and seems to not have been super reliable until 1942-43? Still, it is fun to play around with ideas of re-engining these old airplanes.


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## Nivek (Jul 22, 2017)

Re-engined Yak for racing:

Czech Mate


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## Nivek (Jul 22, 2017)

Nivek said:


> Those are good points. My thoughts: The R-2600 is about 7" larger diameter and I wanted to keep the pilot to top of engine cowl relationship the same. So the engine thrust line is lower than the thrust line of the R-1830 while the top of the engine is about the same place. I used the firewall as a base line for engine installation and the R-2600 is about 3 inches longer than the R-1830. The larger engine will most likely need a larger propeller hub so the front of the engine from the firewall is about 3-6 " farther out. To compensate for the increased front weight I added structure to the rear of the fuselage by increasing its vertical cross section and lengthening the fuselage as much as might be necessary. I think this would also clean up the airflow on the bottom of the fuselage. I don't know how much that would be so I just guessed at a minimum of 12 inches. Moving the battery and radio farther aft along with increasing the strength and weight of the rear fuselage may be enough? ....I supposed more length could be added as necessary.
> 
> The length of the prop may need to be a little longer if the increase power cannot be utilized by changing the design of the propeller width/cord. The wing has a cord that could be lengthened to the rear as it extends farther out from the fuselage. This would allow for an increase in landing gear length. Also this would add a little weight to the rear of the center of gravity. It also would increase the wing area a little. This would minimize the wing loading change with the added weight.
> 
> But as someone said, The R-2600 had early development issues and seems to not have been super reliable until 1942-43? Still, it is fun to play around with ideas of re-engining these old airplanes.




I am not an engineer, just a mechanic/technician. It appears one way change the propeller to use an increase in power is to change propeller area with width rather than length.


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## swampyankee (Jul 22, 2017)

Nivek said:


> I am not an engineer, just a mechanic/technician. It appears one way change the propeller to use an increase in power is to change propeller area with width rather than length.


More diameter is always better, but it may be constrained by aircraft geometry or tip speed, then, yes, you start increasing activity factor, by adding blades or increasing chord. Either would require changes to the hub and pitch-change mechanism or, at an absolute minimum, new structural analysis of the hub and to see if there's enough force and power from the pitch change mechanism.

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## wuzak (Jul 22, 2017)

Nivek said:


> Those are good points. My thoughts: The R-2600 is about 7" larger diameter and I wanted to keep the pilot to top of engine cowl relationship the same. So the engine thrust line is lower than the thrust line of the R-1830 while the top of the engine is about the same place. I used the firewall as a base line for engine installation and the R-2600 is about 3 inches longer than the R-1830. The larger engine will most likely need a larger propeller hub so the front of the engine from the firewall is about 3-6 " farther out. To compensate for the increased front weight I added structure to the rear of the fuselage by increasing its vertical cross section and lengthening the fuselage as much as might be necessary. I think this would also clean up the airflow on the bottom of the fuselage. I don't know how much that would be so I just guessed at a minimum of 12 inches. Moving the battery and radio farther aft along with increasing the strength and weight of the rear fuselage may be enough? ....I supposed more length could be added as necessary.
> 
> The length of the prop may need to be a little longer if the increase power cannot be utilized by changing the design of the propeller width/cord. The wing has a cord that could be lengthened to the rear as it extends farther out from the fuselage. This would allow for an increase in landing gear length. Also this would add a little weight to the rear of the center of gravity. It also would increase the wing area a little. This would minimize the wing loading change with the added weight.
> 
> But as someone said, The R-2600 had early development issues and seems to not have been super reliable until 1942-43? Still, it is fun to play around with ideas of re-engining these old airplanes.



A similar example to what you want to do is the Spitfire XIV.

In order to improve the pilot's view the Griffon in the XIV was canted down a small amount. This reduced ground clearance, and resulted in the XIV having a smaller diameter prop than the Merlin powered IX. The solution was to add blades and run it at higher speed.

Your re-engined P-36 would likely have to do the something similar. 

Changing the wing and landing gear sounds like a lot of extra work.

Also, the P-36 did have the R-1820 installed in at least one version:



> The Norwegian government had issued an order for 36 Hawk 75A-8 export versions of the P-36 just before the German occupation. These aircraft were powered by the export-model 1200 hp Wright R-1820-G205A Cyclone radial. Since Norway was under German occupation at the time these aircraft were completed in January of 1941, they were impounded by the US government.



Curtiss P-36G

The R-1820 was the same diameter as the R-2600.

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## Nivek (Jul 22, 2017)

Comparison between Lavochkin LA-5 and Curtiss P-36. 
P-36 introduced 4 years before LA-5. 
Similar physical dimensions except for Horse Power. 
Suggest performance potential with re-engined P-36.


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## Shortround6 (Jul 24, 2017)

We have to remember that the P-40 was a re-engined P-36 and any scheme to use the R-2600 in a P-36/P-40 airframe has to be compared to the P-40 and not the P-36. 

The R-2600 made a lot of power at low altitude, at high altitude ( and here we are talking about 10,000ft as high altitude) things don't look so good. There were also 3 different R-2600 engines so lets not confuse those either. 

Radial engine installations got much better with time. A 1944 radial installation was much better from a drag standpoint than a 1938 radial installation, they also learned to use exhaust thrust much better. Even the F4U-1 didn't make use, if any of exhaust thrust. 

Having said all that as background the early R-2600 made 1600hp/2400rpm for take-off on 91 octane fuel, it made 1600hp/2400rpm at 1,000 ft ( yes, 1,000ft) in low gear military power and 1400hp/2400 at 10,000ft.

Using early American 100 octane fuel allowed no increase in power but did change the altitude ratings. 1600hp up to 1500ft and 1400hp to 11,500ft. 

The XP-40 was fiddled with until it had 22% less drag than an P-36. SO an early P-40 with 1090hp at 13,200 ft compares to R-2600 with about 1345hp at that altitude. But the R-2600 powered plane needs about 1330hp * IF *it had the same drag as as P-36. Which it won't due to the larger size of the engine and the greater cooling air flow through the cowl needed to cool it. 

Design work on the R-2600B (the 1700hp version with 1450hp at 14,1000ft ) was started in Nov 1938, the first experimental engine ran in Nov 1939 and the 5th production engine ran in June of 1941. Or about one month different than the P-40D going into production and the first flight of the XP-40F with Merlin engine. 

Wright never seemed to get it's act together concerning superchargers until it was too late to really matter. 

Sticking a R-2600 in a P-36/P-40 airframe seems like a lot of work for very little return. 

P&W did get a radial engined P-40 to almost match the P-40 in drag (8% more drag) but not until late 1941 at best and more likely 1942. 
How much of the difference may be exhaust thrust is questionable 

GO to 
P-36 Flight Tests

P-40 Performance Tests

For some test that show the amount of power used at different speeds (including cruise) for the P-36 and P-40 for confirmation of the much lower drag of the P-40. 

An R-2600 powered Curtiss just didn't offer anything the Allison powered plane couldn't do.

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## Nivek (Jul 26, 2017)

Yes, I agree with you. the Allison V12 in that air frame was the best idea and it worked out well. It did the job when needed. The P-40 made sense. 

Just from curiosity, I still wonder what the big engine results would have been. 

(_1,450 hp (1,080 kW) at 2,600 rpm at 15,000 ft (4,575 m) military power_) 

Not an altitude engine but not a bad number for 1942. How much HP was the Allison making at 15K ft in 1942? 

A lot of effort and time went into put the XP-37.

_(XP-37: The aircraft flew in April 1937, reaching 340 mph (550 km/h) at 20,000 ft (6,100 m). Although the turbo-supercharger was extremely unreliable and visibility from the cockpit on takeoff and landing was virtually nonexistent, the USAAC was sufficiently intrigued by the promised performance to order 13 service test *YP-37*s. Featuring improved aerodynamics and a more reliable turbo-supercharger, the aircraft first flew in June 1939. However, the powerplant remained unreliable and the project was cancelled in favor of another Curtiss design, the P-40.)
_
R2600 in P-36/P40 air frame I guess would not be much more effort than they put into the various versions of the XP-37 and XP-42.

We will never know.


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