# 1941/42: fighter with single stage R-2800, a missed opportunity?



## tomo pauk (Sep 5, 2012)

An invitation for the discussion: how well would the Allied air forces fared with a fighter made around the single stage R-2800, production starting in second half of 1941 (1733 engines delivered in 1941, per table posted at the AEHS)?


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## davebender (Sep 5, 2012)

What was the average life expectancy of a R-2800 engine during 1941?


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## Shortround6 (Sep 5, 2012)

The vast majority of those engines were the "A" series and the most common model is the -5. 

1850hp at take-off 2600rpm and 49in of boost. Military ratings of 1850hp/2,600rpm/2,700ft and 1,500hp/2,600rpm/14,000ft. "normal" (max continuous) 1500hp/2400rpm/7,500ft and 1450hp/2400rpm/13,000ft. 

weight 2270-2300lbs and a frontal area of 14.8sq ft. 

it might have 1280hp at 20,000ft no RAM. 

Compare to your favorite engine of the second half of 1941?


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## ShVAK (Sep 5, 2012)

What's the point? USAAF needed a good high altitude fighter in the ETO, I don't think anything with a single stage engine would've cut it. If the fighter is big enough for a two-stage R-2800 and all its accompanying hardware all you have is a redundant competitor to the P-47, and in the meantime it would've probably shared the fate of the P-40--durable and good for low to medium altitude and ground attack, not much else.


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## tomo pauk (Sep 6, 2012)

davebender said:


> What was the average life expectancy of a R-2800 engine during 1941?



As good as of other US produced engines?



Shortround6 said:


> The vast majority of those engines were the "A" series and the most common model is the -5.
> 
> 1850hp at take-off 2600rpm and 49in of boost. Military ratings of 1850hp/2,600rpm/2,700ft and 1,500hp/2,600rpm/14,000ft. "normal" (max continuous) 1500hp/2400rpm/7,500ft and 1450hp/2400rpm/13,000ft.
> 
> ...



Many thanks. 
Seem like it was better the BMW-801C (1300 HP @ 14840), and the B series being better than the 801D, even if the BMW is not restricted.



ShVAK said:


> What's the point? USAAF needed a good high altitude fighter in the ETO, I don't think anything with a single stage engine would've cut it. If the fighter is big enough for a two-stage R-2800 and all its accompanying hardware all you have is a redundant competitor to the P-47, and in the meantime it would've probably shared the fate of the P-40--durable and good for low to medium altitude and ground attack, not much else.



USAAF in 1941-mid 1943 did not wanted an high altitude fighter in the ETO, and the one they had was a problematic one. Single stage R-2800 has 20% more power than the single stage, 2 speed Merlin (I admit, more weight drag); it's more powerful than the BMW 801. Further, it's not necessary to build an 6 ton fighter to support the 2800. Look at the late war Japanese fighters, for example.
The fighter with 1-stage R-2800 was pretty much feasible in 1941, doubt it was the case for the turbo R-2800 (corrections welcomed).


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## wuzak (Sep 6, 2012)

tomo pauk said:


> USAAF in 1941-mid 1943 did not wanted an high altitude fighter in the ETO, and the one they had was a problematic one. Single stage R-2800 has 20% more power than the single stage, 2 speed Merlin (I admit, more weight drag)



Which 2 speed single stage Merlin? The XX had 1430hp @ 11,000ft and weighed approximately 900lbs less. Take away some for the rad and you are still looking at 500-600lbs difference.

What about single stage Griffons? The Griffon II has less power down low, 1735hp @ 1000ft, but similar at altitude - 1495hp @ 14,500ft. Still lighter (1790lb) than the R-2800 with less frontal area.


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## tomo pauk (Sep 6, 2012)

The 1st issue is availability. In the time USA starts producing the A series R-2800s, the single stage Merlin is more a year away from the production by Packard. By the time the V-1650-1 is in production, the R-2800 B series is being produced. 
Second issue, power: we are looking at 1300 HP at 20000 ft, vs. 1050 of the Merlin XX, or almost 25% more. (yes, I'm a proponent of the Merlin XX on Spits Mustangs  ) On military rating, it's 1550 HP @ 11000 ft vs. 1280 HP (all figures for B series vs the XX)?

Griffon is as good as unavailable for the US produced planes, even for the British built airframes prior 1943. So we can have an equivalent of the Spit XII a full year earlier?

If I may return at the post by SHvak:



> What's the point? *USAAF needed a good high altitude fighter in the ETO,* I don't think anything with a single stage engine would've cut it.



The thread is about allied usage of a plane, not only USAAFS's. Costumers include the RAF/CW, VVS etc.
Then, the USAAF in 1941-43 (and beyond, of course) needed a plane that would threat IJA/IJN opposition, and a Hayate-sized plane with R-2800 would've fit there just fine. Second area of interest is the MTO, not much of high flying duties there prior 1943, but plenty of under-20000 ft action. Just for such a fighter.


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## Vincenzo (Sep 6, 2012)

R-2800 is large engine (imho too large only US can afford the price to build a fighter with it) i don't think that a hayate sized plane is enough


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## tomo pauk (Sep 6, 2012)

The single stage R-2800 was needing less space, weighted less and was of lower price than the 2-stage R-2800; the turbo R-2800 was of course the king in weight, volume used cost. So the planes built around that version are bound to cost less than historical F4U (even of we make allowance for the wing folding other CV stuff), and far less than the P-47.
On the other hand, I'd venture to say that the other big radials, either US or other, were of similar price (BMW-801, ASh-82, plethora of Japanese engines, Hercules?), or at least coming until 90% of the R-2800 price. Ditto for the big inlines (Jumo 213, Griffon, Sabre), let alone the coupled engines. The plane with R-2800 can carry a decent bomb load, too, unlike some other 'erzatz' bombers that were proudly carrying a single 250 kg bomb.


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## davebender (Sep 6, 2012)

Ju-87D routinely carried 1,000 kg. Powered by 1,340 hp Jumo 211 V12 engine.


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## Shortround6 (Sep 6, 2012)

tomo pauk said:


> .
> Then, the USAAF in 1941-43 (and beyond, of course) needed a plane that would threat IJA/IJN opposition, and a Hayate-sized plane with R-2800 would've fit there just fine. Second area of interest is the MTO, not much of high flying duties there prior 1943, but plenty of under-20000 ft action. Just for such a fighter.



Good call on the Griffon. 

You are not going to get a R-2800 into a Hayate sized airplane. The Homare engine was 2190 cu in (Wiki is wrong, figure the displacement yourself using the bore and stroke) but the engine was compact, about 6in smaller in diameter (smaller than an R-1830) with a frontal area of 11.8ft. even more importantly it was about 400lbs lighter than an R-2800-5. The R-2800 is about 21% heavier than the Homare. 
You also have the US armament problem. A Hayate carried about 291KG worth of guns and ammo (gun accessories, ammo boxes and links not counted) A P-40E carried about 332 kg and a P-51D carried 385kg. Unless you use the R-2800 to carry just four guns you wind up with 30-90kg more in gun/ammo weight depending on length of firing time desired. 
You need 12-20 more square feet of wing just for the dry weight of the engine and guns/ammo to keep the same wing loading of the Hayate let alone any additional structure needed for the larger, heavier engine and armament. 

Hayate carried 697 liters (?) 184 US gallons of internal fuel. All but 217 liters in the wings. Bigger fuselage of the R-2800 plane may house fuel ( and no fuselage guns) displaced from wings by US wing gun installation. 

Did the Japanese build to the same 12 "G" limit as the Americans?

The Grumman F8F-1 went 9,600lbs with 185 gallons of fuel, I don't think you are going to get much lighter than that. An R-2800 single stage can suck down 60-63 gallons of furl per hour at 1650-1700rpm and 33in MAP at 0-5000ft cruise. Max continuous can be as high 198GPH at 2400rpm and 42in MAP at 5000ft.


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## Shortround6 (Sep 6, 2012)

davebender said:


> Ju-87D routinely carried 1,000 kg. Powered by 1,340 hp Jumo 211 V12 engine.



Ju-87Ds made P***-Poor fighters.


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## davebender (Sep 6, 2012)

My point is you don't need an R-2800 engine to carry a heavy bomb load or to provide an aircraft with significant armor protection.


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## Shortround6 (Sep 6, 2012)

You do (or an engine in it's class) if you also expect the same plane to engage in air to air combat. 

Title of thread is "*1941/42: fighter with single stage R-2800, a missed opportunity?*

*NOT*

"1941/42: CAS aircraft with single stage R-2800, a missed opportunity?"


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## wuzak (Sep 6, 2012)

Did the USAAF know what they needed in 1941?

They were pushing the P-38 pretty hard - that was a high altitude fighter.
They had wanted the P-39 to be turbocharged.
The X/YP-37s were turbocharged.
They took the P-40 because it could be produced in numbers quickly.

I suppose the argument would be that a single stage R-2800 powered fighter could be converted to a 2 stage R-2800 powered fighter relatively easily?


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## Shortround6 (Sep 6, 2012)

Or not so easily depending on initial design. you need 15-20 cubic feet of space for the inter-coolers and ducts and such. 20 cubic ft is a space the entire diameter of the engine and about 15 in deep. You can't cram everything into such a space as you need gentile bends in teh ducts to get them to flow properly and even if you need closer to 15 cu ft than 20 that is a lot of space fairly close to the engine. And no, you can't use the space for fuel on a non-two stage engine 

Inter coolers and ducts are full of air and while bulky don't weigh that much. 

You either design a bigger than needed ( and poorer performing) fuselage/airframe to take the two stage installation later or you design a smaller tighter better performing aircraft for the single stage engine


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## tomo pauk (Sep 7, 2012)

Shortround6 said:


> ...
> You are not going to get a R-2800 into a Hayate sized airplane. The Homare engine was 2190 cu in (Wiki is wrong, figure the displacement yourself using the bore and stroke) but the engine was compact, about 6in smaller in diameter (smaller than an R-1830) with a frontal area of 11.8ft. even more importantly it was about 400lbs lighter than an R-2800-5. The R-2800 is about 21% heavier than the Homare.
> You also have the US armament problem. A Hayate carried about 291KG worth of guns and ammo (gun accessories, ammo boxes and links not counted) A P-40E carried about 332 kg and a P-51D carried 385kg. Unless you use the R-2800 to carry just four guns you wind up with 30-90kg more in gun/ammo weight depending on length of firing time desired.
> You need 12-20 more square feet of wing just for the dry weight of the engine and guns/ammo to keep the same wing loading of the Hayate let alone any additional structure needed for the larger, heavier engine and armament.



Hmm, what's your take about the P-51 sized plane that has 1-stage R-2800, compared with, say, historical P-51D? Maybe the wing area of some 250 sq ft? 6 guns, 350 rpg? I'm not trying to have a plane doing 430 mph, but 400 seem within reach?



> Hayate carried 697 liters (?) 184 US gallons of internal fuel. All but 217 liters in the wings. Bigger fuselage of the R-2800 plane may house fuel ( and no fuselage guns) displaced from wings by US wing gun installation.



250 gals internal should be fine for the 'Fat-51?', plus drop tanks? Again, I'm not trying to escort any bombers in Germany proper in 1941/42.



> Did the Japanese build to the same 12 "G" limit as the Americans?



Don't think so.



> The Grumman F8F-1 went 9,600lbs with 185 gallons of fuel, I don't think you are going to get much lighter than that. An R-2800 single stage can suck down 60-63 gallons of furl per hour at 1650-1700rpm and 33in MAP at 0-5000ft cruise. Max continuous can be as high 198GPH at 2400rpm and 42in MAP at 5000ft.



Thanks (time and again) for the figures.


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## wuzak (Sep 7, 2012)

tomo pauk said:


> Hmm, what's your take about the P-51 sized plane that has 1-stage R-2800, compared with, say, historical P-51D? Maybe the wing area of some 250 sq ft? 6 guns, 350 rpg? I'm not trying to have a plane doing 430 mph, but 400 seem within reach?



So, you're looking for an aircraft with similar performance and size to the P-51A but with a single stage R-2800?


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## tomo pauk (Sep 8, 2012)

Something like that; the resulting plane is to be as fast on military power (15 min rating) as it was the P-51A on WEP (5 min rating), some 2 years earlier. Or, it's performance should be somewhere between FW-190s with BMW-801Cs/restricted 801Ds and un-restricted 801Ds (restriction removed in Autumn 1942). Or, similar to the Spit XII, but 18 months earlier.


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## wuzak (Sep 8, 2012)

Surely "2 years earlier than P-51A" is quite a bit earlier than "18 months earlier than the Spit XII"? If it is the latter then the performance will be at about the same time as the P-51A?

Of course, if they don't particularly want the P-51A at the time, would they want the R-2800 equivalent?


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## Shortround6 (Sep 8, 2012)

I think there is a little something wrong with the time line. The Contract for the P-51A is placed June 23, 1942. two years earlier there are a grand total of 6 R-2800 production engines. 1st production P-51 flies in March of 1943. 

Now the performance you want is harder to estimate. So much depends on the _drag_ of the R-2800 installation. At 14-15,000ft you have about 33% more power than a late model Allison but then in 1939 or so an R-1830 had 22% more drag than an Allison in a P-40. How much of the P-51s lower drag compared to the P-40 is due to simple shape? how much due to the wing? how much due to the radiator (Meredith effect)?

The R-2800 is bigger in diameter than the R-1830 and has more frontal area, it is also going to need about 50% more airflow through the cowl for cooling. How much more drag than an R-1830 installation? This is going to eat up some of the HP advantage. There is no (or darn little) Merideth effect from the aircooled engine to offset the cooling drag (at least at this point in time, later installations got better). 

Then there is the exhaust thrust question. The Allison certainly has it. Will your fighter? the early F4Us did not with two exhaust out lets down low. The F6F was better but piped the cylinders to grouped outlets just over the wing. You get the most thrust with the highest pressure at the pipe exit. sending the exhaust through 4 ft of pipe tends to slow it down and reduce the pressure. You can chose to use individual exhausts like on a B-25 but adding 18 bumps to the cowl doesn't do much for streamlining. 

Then you have the weight question. Considering that this is a new airframe we will forget about the CG and such. But a single stage R-2800 weighs about as much as a 2 stage Merlin with cooling system used in the P-51B&C. The bigger cowl, cowl flaps, engine mounts and such may add another 100lbs. 

When all is said and done you are going to wind up with a plane mighty close to 10,000lbs loaded but clean. While the weight may not affect the top speed much it is going affect the climb, altitude and turning. 

You have a 10,000lb plane with 1500hp at 14,000ft compared to the F4U 12,000lbs with 1800hp at 15,500ft or 1190hp (?) at 22,500 ft compared to the F4U's 1650hp. 

That is pretty much the problem with the concept. There is going to be a very small window of time when the R-2800 is on offer (promised at some point in the future) _without_ the two stage supercharger. After all two different airplanes were using two stage supercharged R-1830s in the Jan 1939 fighter trials. Now how much time and effort do you put into designing and finding manufacturing space for a fighter you *KNOW* will be second rate just as soon as P&W gets the bugs out of the R-2800 with two stage supercharger? 

And just like the problems with the turbo on the P-47, most everybody expected the problems to be sorted out sooner than later. 

Once you have tied up millions of dollars in this fighter, how soon can you convert the factory to something else once the two stage engines are available?


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## gjs238 (Sep 8, 2012)

tomo pauk said:


> An invitation for the discussion: how well would the Allied air forces fared with a fighter made around the single stage R-2800, production starting in second half of 1941 (1733 engines delivered in 1941, per table posted at the AEHS)?



Forget about future R-2800 2-stage development.
Just build a 1-stage land-based fighter.
This is sounding like the land-based F4U threads.


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## Shortround6 (Sep 8, 2012)

The problem with forgetting the two stage development is that you are betting the opposing fighters _*never*_ develop a two stage (or other altitude power boosting system). 

Horse power for the A series vs the B series two stage are in a previous post. 

The "B" series engine, single stage, offered 2000hp at take off, 2000hp at 1500ft and 1600hp at 13,500ft. 1534hp at 15,500ft and 1255hp at 22,500ft. Having 76% of the power of the two stage engine at 22,500ft is going to call for a _*a lot of sacrifice*_ in order to offer similar performance. The two stage system, bulky as it was, is certainly not going to suck up the majority of the power difference. 

Getting rid of the carrier equipment isn't likely to make up the difference either. Even the folding wings. You *may* be able to make a better fighter for use from sea level to 15-16,000ft but giving up the higher altitude or depending on P-47s and P-38s for top cover doesn't sound like it is really solving a problem.


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## tomo pauk (Sep 9, 2012)

wuzak said:


> Surely "2 years earlier than P-51A" is quite a bit earlier than "18 months earlier than the Spit XII"? If it is the latter then the performance will be at about the same time as the P-51A?
> 
> Of course, if they don't particularly want the P-51A at the time, would they want the R-2800 equivalent?



Sorry for the time mismatch - I was going after deployment dates (that mens overseas deployment for the P-51A), not the production dates. 'My' fighter should roll of the production lines some time at Jan/Feb 1941.



Shortround6 said:


> I think there is a little something wrong with the time line. The Contract for the P-51A is placed June 23, 1942. two years earlier there are a grand total of 6 R-2800 production engines. 1st production P-51 flies in March of 1943.



Thanks for the info, guess I could read that stuff myself.



> Now the performance you want is harder to estimate. So much depends on the _drag_ of the R-2800 installation. At 14-15,000ft you have about 33% more power than a late model Allison but then in 1939 or so an R-1830 had 22% more drag than an Allison in a P-40. How much of the P-51s lower drag compared to the P-40 is due to simple shape? how much due to the wing? how much due to the radiator (Meredith effect)?
> 
> The R-2800 is bigger in diameter than the R-1830 and has more frontal area, it is also going to need about 50% more airflow through the cowl for cooling. How much more drag than an R-1830 installation? This is going to eat up some of the HP advantage. There is no (or darn little) Merideth effect from the aircooled engine to offset the cooling drag (at least at this point in time, later installations got better).
> 
> ...



Thanks for the numbers estimates.
No quarrels about the 2-stage engine being far superior than the 1-stage. What I'm after is the engine that can beat the 'bread butter' V-1710s and R-1830s of the era, and there (in 1941), the 1 stage R-2800 fits the bill. The 2 stage does not, its some 14 months late. 
We can envision the 200 gal fighter, too, in order to bring the loaded weight down to 9000-9500 (more akin to Fw-190As).



> That is pretty much the problem with the concept. There is going to be a very small window of time when the R-2800 is on offer (promised at some point in the future) _without_ the two stage supercharger. After all two different airplanes were using two stage supercharged R-1830s in the Jan 1939 fighter trials. Now how much time and effort do you put into designing and finding manufacturing space for a fighter you *KNOW* will be second rate just as soon as P&W gets the bugs out of the R-2800 with two stage supercharger?
> 
> And just like the problems with the turbo on the P-47, most everybody expected the problems to be sorted out sooner than later.
> 
> Once you have tied up millions of dollars in this fighter, how soon can you convert the factory to something else once the two stage engines are available?



The key thing for a weapon is not performance, but timing availability. As exemplified by P-38/39/40, F4F, or Hurricane. One thousand of fighters that can make 390 mph in winter of 1941/42 is a far better proposal than one thousand of fighters that can make 410 mph in winter of 1942/43. A simple, available and decent performer is also of far better use for the allies, than a complicated over-performer that is available once the war is almost won.
As for converting a factory to produce something else, seem like that the USA was keen to expand factory space (plus some new factories, like the Eastern aircraft) workforce that was producing fighters making 330-360 mph, so a fighter that can do 390 mph (later 400, with series B engine?) looks like a real winner.
As for unavailability of a design to be updated with the 2 stage variant, the ww2 saw many planes that went from simple engines to 'complicated' heavier ones (Spitfire, P-51, italian series 5 fighters). I can't prove that 'my' fighter can't receive such an upgrade, but dismissing it easily is maybe too much?


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## Shortround6 (Sep 9, 2012)

If you "size" the fighter to take the 2 stage engine later you have 15-20 cubic feet of space around the engine doing basically nothing. 

View attachment 211130


The center part of the intake at the bottom is intake air for the engine, the outer two intakes are for the inter coolers.







And here we see one of the inter cooling housings. We also see half of the exhaust system. 

"The first flight of the XF4U-1 was made on 29 May 1940" It had a two stage engine even if not the same engine as later versions. 

So when did Vought first know about the 2 stage R-2800? The mock-up inspection was in February 1939. Construction on actual aircraft starts soon after.

As for the P-47, In June of 1940 Republic is told that The XP-44 and Allison powered XP-47 and 47A are to be dropped and a new plane with the R-2800 is wanted quickly. Sept, 6 1940 Authorization for the P-47B is given as a contract change on the XP-47 contract. In Sept of 1940 the US Army orders a total of 733 P-47Bs and P-47cs off the drawing board. This a couple of weeks before the first P-51 prototype has it's engine delivered.It is also before the first Tomahawk IIA is delivered (export P-40B). It is the same month that the P-40D is first ordered and 10 months before the the first P-40D flies. 

Like I said, you have a very, very small window of opportunity in which a single stage R-2800 fighter would be viewed as anything but a temporary expedient and a waste of resources that should be going into the 2 stage-fighters.


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## Shortround6 (Sep 9, 2012)

Duplicate.


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## gjs238 (Sep 10, 2012)

But the US Army never fielded a R-2800 1-stage fighter.
Perhaps a 1-stage R-2800 fighter would have performed better (air to air, air to ground, etc) than the fighters historically available in the early war years?


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## tomo pauk (Sep 10, 2012)

> But the US Army never fielded a R-2800 1-stage fighter.
> Perhaps a 1-stage R-2800 fighter would have performed better (air to air, air to ground, etc) *than the fighters historically available in the early war years*?



More or less that's my point in this thread.



Shortround6 said:


> If you "size" the fighter to take the 2 stage engine later you have 15-20 cubic feet of space around the engine doing basically nothing.
> 
> View attachment 211130
> 
> ...



Thanks for the picture, only one is showing?
The intercooler(s) do not need to be located in the airframe proper, but can be located on other places, say, under fuselage, under wing(s), or in front of the leading edges. Saves quite a lot of space. Granted, the 2 stage R-2800 is longer heavier than 1-stage, so maybe the intrercooler (plus the oil cooler) can take the position resembling the P-51 underbelly cooling system. 



> "The first flight of the XF4U-1 was made on 29 May 1940" It had a two stage engine even if not the same engine as later versions.
> 
> So when did Vought first know about the 2 stage R-2800? The mock-up inspection was in February 1939. Construction on actual aircraft starts soon after.



In the same time, the Navy is trying to find out whether the XFL (Airabointa) is of any use, so maybe they were not 100% sure that F4U is as sure thing as the gold at Fort Knox. Actually, both XFL and F4U 1st flew in May 1940. 
So for me an 'insurance' fighter seem like an order of a day, more so if we took a look at F2A and F4F situation development (one ordered, even if another is the winner at the contest). The 'insurance' fighter, based around 1 stage, A series R-2800 can be fielded by the Navy/Marines/RAF/FAA etc. a full year earlier than a fighter with 2 stage B series R-2800 (ie. far before the Pearl Harbour happened). It can be produced by Eastern aircraft instead of F4F, too. It can beat anything Japanese get airborne with ease, at least before 1944, while holding it's own vs. German oposition. It can defend Malta other convoys far better than Martlet/Fulmar/Sea Hurricane, while the 2 stager is too late for that.



> As for the P-47, In June of 1940 Republic is told that The XP-44 and Allison powered XP-47 and 47A are to be dropped and *a new plane with the R-2800 is wanted quickly*. Sept, 6 1940 Authorization for the P-47B is given as a contract change on the XP-47 contract. In Sept of 1940 the US Army orders a total of 733 P-47Bs and P-47cs off the drawing board. This a couple of weeks before the first P-51 prototype has it's engine delivered.It is also before the first Tomahawk IIA is delivered (export P-40B). It is the same month that the P-40D is first ordered and 10 months before the the first P-40D flies.



USAAF wants a new plane with R-2800 quickly, yet they opt of the most complicated option. They also opt for the P-63 (June 1941), while Curtiss is busy with XP-46 -60 (despite the orders for the P-47Gs from them) - second thoughts re. P-47 turbo R-2800 itself? Again, the simple 1-stager can be produced from early 1941, so the Allies can use them far earlier than a working turboed R-2800 fighter, yet of far better capabilities than it was possible for the historic US fighters, prior mid 1943.



> Like I said, you have a very, very small window of opportunity in which a single stage R-2800 fighter would be viewed as anything but a temporary expedient and a waste of resources that should be going into the 2 stage-fighters.



How big is the window of opportunity can be measured in more ways than one. If your turbo R-2800 fighter enters issues that take time to resolve, firm 2 years of service as one of the top fighters is quite an achievement, even more so if the whole war is 4 years long. If one can equip your allies with a fine performer, the allies can make a better job on their own. 
As for the naval bird, it can be ready in service for the major naval actions of 1942, unlike the 2 stager. Even in 1943, it does not like a temporary expedient, but more likely as a fine performer. Far better than the F4F.


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## wuzak (Sep 10, 2012)

tomo pauk said:


> The intercooler(s) do not need to be located in the airframe proper, but can be located on other places, say, under fuselage, under wing(s), or in front of the leading edges. Saves quite a lot of space. Granted, the 2 stage R-2800 is longer heavier than 1-stage, so maybe the intrercooler (plus the oil cooler) can take the position resembling the P-51 underbelly cooling system.



For the intercoolers to be remote from the supercharger they either need copious amounts of ducting or to be liquid:air intercoolers. As far as I am aware all the US developed intercoolers were air:air, particularly on air cooled radial applications. Air:air intercoolers require a larger radiator than liquid:air intercoolers. 

If you are using a liquid cooled engine the intercooler can be part of the radiator group - as was the case with the P-51. Or it can be mounted remotely - such as on the Mosquito (inlet under the spinner on 2-stage Mossies). Not sure that a designer who has chosen an air-cooled engine will then want to use a liquid:air intercooler.


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## Shortround6 (Sep 10, 2012)

tomo pauk said:


> The intercooler(s) do not need to be located in the airframe proper, but can be located on other places, say, under fuselage, under wing(s), or in front of the leading edges. Saves quite a lot of space. Granted, the 2 stage R-2800 is longer heavier than 1-stage, so maybe the intrercooler (plus the oil cooler) can take the position resembling the P-51 underbelly cooling system.



Moving them somewhere besides the rear of the engine means they take up more space, not less. Different space but more space, much like the complaints about the P-47 with ducting intake and inter cooler air to and fro in the fuselage. Remember that the P-38 wing leading edge inter-coolers didn't work all that well for powers much over 1000hp per engine and the P-38 had a 52 ft wing. Around 30ft of that was inter-cooler. Look at an F8F, 35 feet of wing span with a fuselage over over 5ft in the middle. You may make it but the wing guns are going to be a problem. Landing gear may or may not be a problem, you may not need it but you just ruled out leading edge fuel tanks. 



tomo pauk said:


> So for me an 'insurance' fighter seem like an order of a day, more so if we took a look at F2A and F4F situation development (one ordered, even if another is the winner at the contest). The 'insurance' fighter, based around 1 stage, A series R-2800 can be fielded by the Navy/Marines/RAF/FAA etc. a full year earlier............. They also opt for the P-63 (June 1941), while Curtiss is busy with XP-46 -60 (despite the orders for the P-47Gs from them) - second thoughts re. P-47 turbo R-2800 itself? Again, the simple 1-stager can be produced from early 1941, so the Allies can use them far earlier than a working turboed R-2800 fighter, yet of far better capabilities than it was possible for the historic US fighters, prior mid 1943.



Who is left to design/build this fighter? Which historical fighter DOES NOT GET BUILT? Or which bomber?

As an example, Bell (making those P-39s) had 1200 employees in Jan 1940, 5000 Employees in Jan 1941 and 10,000 employees and an additional plant in Dec 1941. 

The XP-46 was ordered in Sept 1939., first flight was Jan 1941. XP-50 was ordered in Nov, 1939, first flight Feb 1941. The contract for the Curtiss XP-53 (start of the XP-60 series) was Oct 1 1940. Some rather severe meddling by the Air Corp, coupled with both an inability of the Air Corp to make up their minds what engine to use and Curtiss's apparent inability to get their sums right means that series goes nowhere but quite a bit of work was done before Curtiss ever got a contract for the P-47G. 

The P-40 and P-39 are already "interim" fighters, planes the Air Corp will buy _until_ they can get something better. The idea of _another_ interim fighter until the P-38 and P-47 get sorted out seems a bit far fetched. The P-43 was purchased as much to finance Republic factory expansion and to train/enlarge Republic's work force as to get a combat worthy fighter. 
The Army may have been a little nuts but in the Fall of 1940 they were ordering things like the XP-56 pusher to try to push the envelope. 

Combat reports from the BoB point to the not uncommon altitudes of 25,000-30,000ft at the start of combat, used mostly to bounce aircraft at lower altitudes rather than actual dog fights at those altitudes but still? What will be the needed altitude in 1942-43? 18,000ft or 28,000ft or 33,000ft? 

We have the _LUXURY_ of *knowing* that the Germans and Japanese never developed mass produced propeller planes that could operate (fight) much over 30,000ft and the major exception is the 109. This was certainly not known in 1941/42. 

If the US had really wanted a better performing fighter in the Spring/Summer of 1942 at low altitudes all they had to do was approve the WEP power settings earlier. 



tomo pauk said:


> How big is the window of opportunity can be measured in more ways than one. If your turbo R-2800 fighter enters issues that take time to resolve, firm 2 years of service as one of the top fighters is quite an achievement, even more so if the whole war is 4 years long. If one can equip your allies with a fine performer, the allies can make a better job on their own.
> As for the naval bird, it can be ready in service for the major naval actions of 1942, unlike the 2 stager. Even in 1943, it does not like a temporary expedient, but more likely as a fine performer. Far better than the F4F.



It takes about 1 1/2 years from placing the contract ( preliminary drawings/calculations are already done) to first flight of prototype. It takes another 6 months ( at best) to a year to get the first Squadron or two equipped. it takes several more months to work those squadrons up to true fighting capability rather than field targets for the enemy. There are always dozens of little details that need working out. 
So you either need to start work in the fall of 1939 to spring of 1940 or you need one of the fastest aircraft design and development programs of WW II. And the engine is only a small part of it. Airframe design was not a sure thing. The Vultee fighter went through 3 different tails. The XP-56 practically refused to take-off. Handling problems with the Helldiver are well known. _IF_ you want a _sure thing_ flight wise it means a "standard" for the time airfoil, a standard configuration and standard construction. 

As far as our "allies" doing a better job with it. Our Allies were months ahead of the US in using WEP settings on the Allison and Merlin and had less need of it. 

You had also better make up your mind if this is a land fighter or a Naval fighter. The F4F with it's two stage R-1830 was disliked for it's poor altitude performance ( due to weight), it's just that most of the US fighter competition at the time was even worse. The F4F was also disliked for it's poor endurance/range without drop tanks with 144-147 US gallons for it's R-1830 engine. 200 gallons for an _ALL PURPOSE_ R-2800 Naval fighter is too little. The F8F had a definite role to play and high altitude CAP was not it. That role was filled by the F6F-5 and late F4Us. Carrier fighters had to stay airborne much longer than originally planed for a variety of reasons including a crash of a plane ahead of them in the landing pattern/queue having to ditch planes because of not enough fuel is not a good plan. Especially when replacements could be a week or more away.


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## gjs238 (Sep 12, 2012)

tomo pauk said:


> An invitation for the discussion: how well would the Allied air forces fared with a fighter made around the single stage R-2800, production starting in second half of 1941 (1733 engines delivered in 1941, per table posted at the AEHS)?


 Would a Wright R-2600 powered fighter in that time period be more likely timewise?


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## tomo pauk (Sep 12, 2012)

Maybe a fighter built around the R-2600 is upgraded with 1-stage R-2800, in early 1941?



wuzak said:


> For the intercoolers to be remote from the supercharger they either need copious amounts of ducting or to be liquid:air intercoolers. As far as I am aware all the US developed intercoolers were air:air, particularly on air cooled radial applications. Air:air intercoolers require a larger radiator than liquid:air intercoolers.
> 
> If you are using a liquid cooled engine the intercooler can be part of the radiator group - as was the case with the P-51. Or it can be mounted remotely - such as on the Mosquito (inlet under the spinner on 2-stage Mossies). Not sure that a designer who has chosen an air-cooled engine will then want to use a liquid:air intercooler.


 


Shortround6 said:


> Moving them somewhere besides the rear of the engine means they take up more space, not less. Different space but more space, much like the complaints about the P-47 with ducting intake and inter cooler air to and fro in the fuselage.


 
No quarrels about 2 stage R-2800 needing a decent volume for it's intercoolers associate plumbing. Having a separate 20 ft ducting to 'bring' the air to the intercooler (= P-47) is in stark contrast with P-51 type layout of (not only) intercooler; we need to add there the volume needed for the exhaust gases ducting that obviously was not a part of the mech-supercharged 2 stage R-2800. So we need two pipes, one to and another from the intercooler.



> Remember that the P-38 wing leading edge inter-coolers didn't work all that well for powers much over 1000hp per engine and the P-38 had a 52 ft wing. Around 30ft of that was inter-cooler. Look at an F8F, 35 feet of wing span with a fuselage over over 5ft in the middle. You may make it but the wing guns are going to be a problem. Landing gear may or may not be a problem, you may not need it but you just ruled out leading edge fuel tanks.



I do not see the reason to use P-38 type of intercoolers. Mount the same type that were used in the F6F F4U, but just outboard of the leading edge and you're set.



> Who is left to design/build this fighter? Which historical fighter DOES NOT GET BUILT? Or which bomber?
> 
> As an example, Bell (making those P-39s) had 1200 employees in Jan 1940, 5000 Employees in Jan 1941 and 10,000 employees and an additional plant in Dec 1941.



NAA, Vultee, Severky/Republic, later Easter aircraft, Goodyear, Northrop, Bell? 
No P-43, Vengeance, P-63, less B-26s? 



> The XP-46 was ordered in Sept 1939., first flight was Jan 1941. XP-50 was ordered in Nov, 1939, first flight Feb 1941. The contract for the Curtiss XP-53 (start of the XP-60 series) was Oct 1 1940. Some rather severe meddling by the Air Corp, coupled with both an inability of the Air Corp to make up their minds what engine to use and Curtiss's apparent inability to get their sums right means that series goes nowhere but quite a bit of work was done before Curtiss ever got a contract for the P-47G.
> 
> The P-40 and P-39 are already "interim" fighters, planes the Air Corp will buy _until_ they can get something better. The idea of _another_ interim fighter until the P-38 and P-47 get sorted out seems a bit far fetched. The P-43 was purchased as much to finance Republic factory expansion and to train/enlarge Republic's work force as to get a combat worthy fighter.
> The Army may have been a little nuts but in the Fall of 1940 they were ordering things like the XP-56 pusher to try to push the envelope.



Thanks for the insight. Army was trying hard with 1200 HP fighters, so a 2000 HP one is hardly a far fetched thing.



> Combat reports from the BoB point to the not uncommon altitudes of 25,000-30,000ft at the start of combat, used mostly to bounce aircraft at lower altitudes rather than actual dog fights at those altitudes but still? What will be the needed altitude in 1942-43? 18,000ft or 28,000ft or 33,000ft?



Army _expects_ that it's turbo fighters would do fine. They do not know for sure whether the turbo will be sorted out to work flawlessly, let alone that it would be easily operated by a single person (that should be looking to kill something while flying in war, too). So they give a chance to a plane that can have almost 1000 HP at 30000 ft, or more than twice as the V-1710s that are to be produced from 1939-43.



> We have the _LUXURY_ of *knowing* that the Germans and Japanese never developed mass produced propeller planes that could operate (fight) much over 30,000ft and the major exception is the 109. This was certainly not known in 1941/42.



Agreed. 



> If the US had really wanted a better performing fighter in the Spring/Summer of 1942 at low altitudes all they had to do was approve the WEP power settings earlier.



Not something I'd agree, on several points.
WEP was not applicable for F4F and F2A (nor F4U/F6F without ADI). For P-39 -40, WEP means high power down low (under 10-12000 ft), so it's rather away from the high altitude mantra. We can take a look at troubles catching IJA/IJN planes flying above mere 15000 ft, and troubles vs. 109/190. WEP was not applicable for the P-40B/C, since the power above 1200 HP would've cracked the reduction gear; for the P-38, the WEP became reality in mid 1943.
As for the WEP itself, it was not just some kind of the switch for pilots to open up when wanting more power. It required testing, approval and increased maintenance, so next time pilot overboosts the engine, it's not damaged. WEP was 5 min rating, military was 15 min rating. The early war US fighters were overweighted when carrying 6 HMG (or P-39s arsenal) plenty of fuel (not P-39, it was not capable for such 'extravaganza'), unlike the 1700+ HP fighters. With 250 gals of fuel, the R-2800 fighter can have it all: range, performance, punch protection, unlike the early types.



> It takes about 1 1/2 years from placing the contract ( preliminary drawings/calculations are already done) to first flight of prototype. It takes another 6 months ( at best) to a year to get the first Squadron or two equipped. it takes several more months to work those squadrons up to true fighting capability rather than field targets for the enemy. There are always dozens of little details that need working out.
> So you either need to start work in the fall of 1939 to spring of 1940 or you need one of the fastest aircraft design and development programs of WW II. And the engine is only a small part of it. Airframe design was not a sure thing. The Vultee fighter went through 3 different tails. The XP-56 practically refused to take-off. Handling problems with the Helldiver are well known. _IF_ you want a _sure thing_ flight wise it means a "standard" for the time airfoil, a standard configuration and standard construction.



Fair reasonable points. 



> As far as our "allies" doing a better job with it. Our Allies were months ahead of the US in using WEP settings on the Allison and Merlin and had less need of it.



Allied pilots were surely fighting dying, in hundreds if not thousands, hats of to the men. But, in Europe, 1941-42, they were flying the fighters decidedly inferior to what the LW was fielding. In Asia, they were fighting with, almost, cast offs, while outnumbered. No WEP setting is going to help the P-40 pitted vs. 109F when above 10000 ft, nor the P-39 is going to catch the Betty Zero that are at 15000 ft. The less we talk about Soviet disadvantage in performance, the better. So the Allied pilots were in dire need to forestall the multiple:1 loss ratios, more so than the US ones.



> You had also better make up your mind if this is a land fighter or a Naval fighter.



Two similar designs - one naval, another land based.



> The F4F with it's two stage R-1830 was disliked for it's poor altitude performance ( due to weight), it's just that most of the US fighter competition at the time was even worse.



Weight had nothing to do with the poor altitude performance - the wing loading was less than of P-39 of P-40. What doomed any performance was the substantial drag - the Cd0 was greater than of P-47, while the wing was of substantial area (260 sq ft). Asking from the R-1830, even the two stager, to make a performer of a draggy airplane is asking too much. 
We can note that, in 1942, it was entirely possible to have a fighter with 2000-1500 HP (B series R-2800) vs. 1200-1000 HP (2 stage R-1830), from SL up to 16000 ft, that would be a tad less draggier than the F4F. Couple of carriers more for 1943? Or, for 1941-42 land based aircraft, the demise of the Fw-190?



> . The F4F was also disliked for it's poor endurance/range without drop tanks with 144-147 US gallons for it's R-1830 engine. 200 gallons for an _ALL PURPOSE_ R-2800 Naval fighter is too little.


You can note that 250 gals of fuel was my 1st call, not 200 (though the resulting fighter would be a better performer when based around less int. fuel). 



> The F8F had a definite role to play and high altitude CAP was not it. That role was filled by the F6F-5 and late F4Us. Carrier fighters had to stay airborne much longer than originally planed for a variety of reasons including a crash of a plane ahead of them in the landing pattern/queue having to ditch planes because of not enough fuel is not a good plan. Especially when replacements could be a week or more away.



Fair points; I'm not trying to 'build' a short-burn VF.


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## Shortround6 (Sep 12, 2012)

tomo pauk said:


> So we need two pipes, one to and another from the intercooler.



Yep. One inlet pipe leading back to the inter cooler from the first stage supercharger and another pipe from the inter cooler back to the second stage. Of roughly the cross section of the middle third of a Hellcats air intake. 



tomo pauk said:


> I do not see the reason to use P-38 type of intercoolers. Mount the same type that were used in the F6F F4U, but just outboard of the leading edge and you're set.


 Well, the F4U may have had the intakes in the wing leading edge but the intercoolers were in the fuselage behind the engine much like the Hellcats. Both planes had substantial wings. Both had landing gear that retracted rearward. A wing the size of the Mustang and using inward retracting gear may be using the wing leading edge and wing root for landing gear wells. 





tomo pauk said:


> NAA, Vultee, Severky/Republic, later Easter aircraft, Goodyear, Northrop, Bell?
> No P-43, Vengeance, P-63, less B-26s?



Thank you for making my point. _IF_ NAA is busy making this thing what aren't they building? British approached NAA becaseu they thought they had spare prodcution capacity or could rapidly build production capacity. Your fighter _INSTEAD_ of the P-51 and not in addition to it? Fewer B-25s? Fewer AT-6s? Not used in combat but there goes some of the later American advantage in better trained pilots. 
Same for Severky/Republic only worse, little or no real production capacity, Before the P-43 contract they hadn't built over 100 planes in the companies history. Eastern Aircraft doesn't exist until the spring of 1942. It used 5 or more General Motors car factories ( plus about 3000 sub contractors). Eastern Aircraft never designed an airplane. Same with Goodyear, unless you count blimps. You have got to be kidding with Bell??? I am not sure these guys ever got the predicted numbers right on any fixed wing aircraft. 
Maybe fewer P-39s and P-63s would have been a good thing but your fighter is later in timing than the P-39 and if it interferes with P-39 production in 1939/40???
Jack Northrop Split from Douglas and formed his own company (his third) in 1939. Maybe he could have built your fighter, if he wasn't distracted by the XP-56  But again he had no real production facility in 1939/40, The P-61 Black Widow may have been the first production aircraft for the new company. 

Vultee? " AVCO hired Dick Palmer away from Howard Hughes to take Jerry's place, and Vultee Aircraft Division began to develop military designs. Dick Palmer created the BT-13, BT-15, and SNV Valiant trainers[2] and oversaw other major production program such as the V-72 Vengeance, serving in the USAAC as the A-31 and A-35. The AVCO Vultee division became the separate Vultee Aircraft Corporation in 1939.[2] The P-66 Vanguard was a 1941 fighter program that was intended for Sweden that was inherited by the USAAC, Great Britain and finally, China. The P-66 had a mediocre combat record in China and was out of service by 1943. The XP-54 fighter project was the last Vultee Aircraft design but only two examples were built." The Vengeance was pretty much Vultee's high point. 

We are pretty much back to who is going to design and build it and what do you give up. 




tomo pauk said:


> Army _expects_ that it's turbo fighters would do fine. They do not know for sure whether the turbo will be sorted out to work flawlessly, let alone that it would be easily operated by a single person (that should be looking to kill something while flying in war, too). So they give a chance to a plane that can have almost 1000 HP at 30000 ft, or more than twice as the V-1710s that are to be produced from 1939-43.



Your almost 1000hp is more like 925hp or so ( for an "A" series R-2800). A Merlin XX should have been good for about 750hp at 30000ft. The two stage R-1830 should have had about 695hp at 30,000ft? How much of that extra 175-230hp is being used to haul around the extra weight and drag of the R-2800 at 30,000ft? And the extra fuel?
"


tomo pauk said:


> Not something I'd agree, on several points.
> WEP was not applicable for F4F and F2A (nor F4U/F6F without ADI). For P-39 -40, WEP means high power down low (under 10-12000 ft), so it's rather away from the high altitude mantra. We can take a look at troubles catching IJA/IJN planes flying above mere 15000 ft, and troubles vs. 109/190. WEP was not applicable for the P-40B/C, since the power above 1200 HP would've cracked the reduction gear; for the P-38, the WEP became reality in mid 1943.
> As for the WEP itself, it was not just some kind of the switch for pilots to open up when wanting more power. It required testing, approval and increased maintenance, so next time pilot overboosts the engine, it's not damaged. WEP was 5 min rating, military was 15 min rating. The early war US fighters were overweighted when carrying 6 HMG (or P-39s arsenal) plenty of fuel (not P-39, it was not capable for such 'extravaganza'), unlike the 1700+ HP fighters. With 250 gals of fuel, the R-2800 fighter can have it all: range, performance, punch protection, unlike the early types.



You originally pitched this idea as better low altitude fighter, in the quoted section of my post I stated "Spring/Summer of 1942 at low altitudes". The British had been using higher than factory recommended boost settings in NA for months ( as did the Flying Tigers) and by the fall of 1942 even US forces had been using higher boost levels at squadron level (unauthorized) and Allison themselves were pushing for higher limits. 

The R-2800 powered fighter can have more, the question is how much more and at what altitudes, and is it worth delaying the better aircraft that are in the design/development stage. Considering that both the Germans and Japanese rather dropped the ball in fighter development. The Fw 190 was fine at low altitudes but the 109G was just marking time compared to a 109F. It was better but not enough better and the later "G"s with the higher powered engines were too late in coming. The Japanese took at least two years too long to switch engines in the Zero ( or get rid of the Ki 43). Depending on the enemy to fail to develop better fighters so your "temporary" fighter can show an advantage is not good planning. 




tomo pauk said:


> Allied pilots were surely fighting dying, in hundreds if not thousands, hats of to the men. But, in Europe, 1941-42, they were flying the fighters decidedly inferior to what the LW was fielding. In Asia, they were fighting with, almost, cast offs, while outnumbered. No WEP setting is going to help the P-40 pitted vs. 109F when above 10000 ft, nor the P-39 is going to catch the Betty Zero that are at 15000 ft. The less we talk about Soviet disadvantage in performance, the better. So the Allied pilots were in dire need to forestall the multiple:1 loss ratios, more so than the US ones.



The Far East and the Soviets were in dire need but they weren't going to get the R-2800 fighter. If the British ship Buffaloes to Singapore in the fall of 1941 instead of MK II Hurricanes or Spitfires what makes you think they would send the few squadrons of R-2800 fighters they were likely to get by then? 

The British "ordered 675 of the export version Bell Model 14 as the "Caribou" on the strength of the company's representations on 13 April 1940" "No. 601 Squadron RAF was the only British unit to use the Airacobra operationally, receiving their first two examples on 6 August 1941. On 9 October, four Airacobras attacked enemy barges near Dunkirk, in the type's only operational action with the RAF." Add at least a month or two to get the planes from England to the Far East. First P-39s the Russians got were part of the batch the British decided they didn't want any more. Russians aren't likely to get any unless the British decide they don't want them for first line use. At least not in the fall/winter of 1941/42 and into the spring. The chances of this fighter out performing a MK V Spitfire at altitude are pretty slim. 





tomo pauk said:


> Two similar designs - one naval, another land based.



More design work??? 





tomo pauk said:


> Weight had nothing to do with the poor altitude performance - the wing loading was less than of P-39 of P-40. What doomed any performance was the substantial drag - the Cd0 was greater than of P-47, while the wing was of substantial area (260 sq ft). Asking from the R-1830, even the two stager, to make a performer of a draggy airplane is asking too much.



It had a lot to do with it. Climb is a reflection of surplus power. Or the power to weight ratio after the power needed to overcome drag is taken out. Now why did the F4F have such a big a wing? Both take-off and landing requirements for carrier operation at the time. These requirements changed as time went on. But in 1939-40 the plane had better land at about the speed of an F4F or the Navy won't buy it. Since this plane is going to weigh about 1 ton more than the F4F it better have a good sized wing. You might be surprised at the difference a few hundred HP can make ( or 1000lbs) to climb in the over 20,000ft area. Navy pilots could tell the difference between F4F-3s, -3As and -4s. All had about the same drag.


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## wuzak (Sep 12, 2012)

tomo pauk said:


> No quarrels about 2 stage R-2800 needing a decent volume for it's intercoolers associate plumbing. Having a separate 20 ft ducting to 'bring' the air to the intercooler (= P-47) is in stark contrast with P-51 type layout of (not only) intercooler; we need to add there the volume needed for the exhaust gases ducting that obviously was not a part of the mech-supercharged 2 stage R-2800. So we need two pipes, one to and another from the intercooler



First, the two stage R-2800s did not need to duct the exhaust gasses anywhere. They could use a style of ejector exhaust, or the exhaust collector manifold system.

Second, the ducting to take the air to the intercooler in the P-47 wasn't necessary as such. The P-47 could just as easily have had a rear fuselage mounted scoop to feed the intercooler. The Republic engineers obviously felt their way was better. Note that on the XP-47J the scoop that feed intercooler and supercharger was moved rearwards from the cowl, but remained under the forward fuselage, still requiring lengthy ducting.


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## wuzak (Sep 12, 2012)

Shortround6 said:


> The chances of this fighter out performing a MK V Spitfire at altitude are pretty slim.



And by the time it gets manufactured in quantity the Spitfire IX wll be coming out, and widening the altitude performance difference.


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## tomo pauk (Sep 13, 2012)

wuzak said:


> First, the two stage R-2800s did not need to duct the exhaust gasses anywhere. They could use a style of ejector exhaust, or the exhaust collector manifold system.
> 
> Second, the ducting to take the air to the intercooler in the P-47 wasn't necessary as such. The P-47 could just as easily have had a rear fuselage mounted scoop to feed the intercooler. The Republic engineers obviously felt their way was better. Note that on the XP-47J the scoop that feed intercooler and supercharger was moved rearwards from the cowl, but remained under the forward fuselage, still requiring lengthy ducting.



Sure enough that 2 stager did not need the exhaust gases duct, sorry for not being crystal clear. Omitting the exhaust gases ducts when talking/criticizing the P-47 belly duct does blur the picture, though.
When the time comes to upgrade the 1 stage fighter with 2 stage R-2800, the belly scoop featuring the boundary layer splitter is well within the state of the art.



wuzak said:


> And by the time it gets manufactured in quantity the Spitfire IX wll be coming out, and widening the altitude performance difference.



By the time Spit IX came out, the RAF was already suffered something like 18 months of receiving the multiple:1 losses above W. Europe. Spit IX was not seen as a viable thing to beat Fw-190 under 15000 ft - RAF was fielding the Spit XII and the low level marks of the V to combat the threat, plus the Typhoon. Spit VIII/IX was not, even in late 1943, the most common Spitfire variant in RAF's inventory, let alone in CW air forces. That Spitfire was not able to pursue the outnumbered LW, say, 250 miles away from the Channel (to be fair, not a culprit of the plane itself). What I'm after is a fighter for 1941-42 anyway, not just for late 1942.


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## tomo pauk (Sep 13, 2012)

Shortround6 said:


> Well, the F4U may have had the intakes in the wing leading edge but the intercoolers were in the fuselage behind the engine much like the Hellcats. Both planes had substantial wings. Both had landing gear that retracted rearward. A wing the size of the Mustang and using inward retracting gear may be using the wing leading edge and wing root for landing gear wells.



I'm not after the internal intercoolers, but the ones that would protrude from leading edge forward (so not Whirlwind, but Mossie layout).



> Thank you for making my point. _IF_ NAA is busy making this thing what aren't they building? British approached NAA becaseu they thought they had spare prodcution capacity or could rapidly build production capacity. Your fighter _INSTEAD_ of the P-51 and not in addition to it? Fewer B-25s? Fewer AT-6s? Not used in combat but there goes some of the later American advantage in better trained pilots.



I'm not making your point. It's about the combined question that I didn't bothered to split up and answer one thing at time.
NAA was capable to design a fighter, any plane they made was an decent- or over-performer. They did not expanded the production lines for the P-51 until the USAAF order came for hundreds of those. Having a plane that attracts USAAF attention and it's ordered in hundred or two, and then the British and French order what's already flying as a prototype, means earlier expansion. 
There is no reason that P-51 doesn't came along - flying for the 1st time in late 1942, instead in 1940, with 2 stage Merlin from start. 



> Same for Severky/Republic only worse, little or no real production capacity, Before the P-43 contract they hadn't built over 100 planes in the companies history.



They can design it. As for the production capacity, there was no way they would expand their production capacity when USAAF orders ~150 planes (= historical P-43). But with USAAF ordering hundreds of planes, they have something to base their future upon, and invest in expansion. Same thing applies for UK French order.



> Eastern Aircraft doesn't exist until the spring of 1942. It used 5 or more General Motors car factories ( plus about 3000 sub contractors). Eastern Aircraft never designed an airplane. Same with Goodyear, unless you count blimps. You have got to be kidding with Bell??? I am not sure these guys ever got the predicted numbers right on any fixed wing aircraft. Maybe fewer P-39s and P-63s would have been a good thing but your fighter is later in timing than the P-39 and if it interferes with P-39 production in 1939/40???



Before 'Eastern aircraft etc.' in my reply, you can notice small word 'later'. That means they start the production later. Ditto for Goodyear Bell. No design job for them.



> Jack Northrop Split from Douglas and formed his own company (his third) in 1939. Maybe he could have built your fighter, if he wasn't distracted by the XP-56  But again he had no real production facility in 1939/40, The P-61 Black Widow may have been the first production aircraft for the new company.



Darn the XP-56 



> Vultee? " AVCO hired Dick Palmer away from Howard Hughes to take Jerry's place, and Vultee Aircraft Division began to develop military designs. Dick Palmer created the BT-13, BT-15, and SNV Valiant trainers[2] and oversaw other major production program such as the V-72 Vengeance, serving in the USAAC as the A-31 and A-35. The AVCO Vultee division became the separate Vultee Aircraft Corporation in 1939.[2] The P-66 Vanguard was a 1941 fighter program that was intended for Sweden that was inherited by the USAAC, Great Britain and finally, China. The P-66 had a mediocre combat record in China and was out of service by 1943. The XP-54 fighter project was the last Vultee Aircraft design but only two examples were built." The Vengeance was pretty much Vultee's high point.



Okay, Jack Northrop can design it and start the production in small numbers, with Vultee joining in in production. 



> We are pretty much back to who is going to design and build it and what do you give up.



We can move on now.



> Your almost 1000hp is more like 925hp or so ( for an "A" series R-2800). A Merlin XX should have been good for about 750hp at 30000ft. The two stage R-1830 should have had about 695hp at 30,000ft? How much of that extra 175-230hp is being used to haul around the extra weight and drag of the R-2800 at 30,000ft? And the extra fuel?



US fighter, carrying the Merlin XX (Packard V-1650-1) in the war is a full year late, when compared with the A series R-2800. 
What the USAAC thought about the 2-stage R-1830 was clear in 1939 - no fighters with that engine were ordered by intended costumer.



> You originally pitched this idea as better low altitude fighter, in the quoted section of my post I stated "Spring/Summer of 1942 at low altitudes". The British had been using higher than factory recommended boost settings in NA for months ( as did the Flying Tigers) and by the fall of 1942 even US forces had been using higher boost levels at squadron level (unauthorized) and Allison themselves were pushing for higher limits.



My idea about the 1-stage fighter was not set in stone by the time the 1st post was made here, but I was looking forward to hear what could be expected from such a plane. Sure enough, the V-12 fighter with 1500 HP, WEP, could beat the radial fighter with 2000 HP under 1000 ft. Problem arises when the 1150 HP fighter is tasked to bring 6 HMGs, 300 miles away, at 20000 ft, beat the performing enemy, and then return. 2000 HP fighter can do that, unlike the 1150 HP fighter.



> The R-2800 powered fighter can have more, the question is how much more and at what altitudes, and is it worth delaying the better aircraft that are in the design/development stage. Considering that both the Germans and Japanese rather dropped the ball in fighter development. The Fw 190 was fine at low altitudes but the 109G was just marking time compared to a 109F. It was better but not enough better and the later "G"s with the higher powered engines were too late in coming. The Japanese took at least two years too long to switch engines in the Zero ( or get rid of the Ki 43). Depending on the enemy to fail to develop better fighters so your "temporary" fighter can show an advantage is not good planning.



P-38 will not be delayed, nor should the P-47. The high-tech/high-risk planes will need some time to iron their bugs. The 1-stager can evolve into a 2-stager, even more so since the airframe designers knew rather in advance about the 2 stager.



> The Far East and the Soviets were in dire need but they weren't going to get the R-2800 fighter. If the British ship Buffaloes to Singapore in the fall of 1941 instead of MK II Hurricanes or Spitfires what makes you think they would send the few squadrons of R-2800 fighters they were likely to get by then?



Availability of the real performer (instead of the P-39/40) might convince the British to ship more of better indigenous fighters abroad. 



> The British "ordered 675 of the export version Bell Model 14 as the "Caribou" on the strength of the company's representations on 13 April 1940" "No. 601 Squadron RAF was the only British unit to use the Airacobra operationally, receiving their first two examples on 6 August 1941. On 9 October, four Airacobras attacked enemy barges near Dunkirk, in the type's only operational action with the RAF." Add at least a month or two to get the planes from England to the Far East. First P-39s the Russians got were part of the batch the British decided they didn't want any more. Russians aren't likely to get any unless the British decide they don't want them for first line use. At least not in the fall/winter of 1941/42 and into the spring. The chances of this fighter out performing a MK V Spitfire at altitude are pretty slim.



Maybe it will beat the Spit V, maybe not. Heavy draggy F4U surely outperformed it. So did the much criticized Typhoon.



> More design work???



Not really, instead of two separate designs, introduce the Corsair-like folding wings of a tad greater area (270 sq ft vs. 240-250 for the land based plane), hook, some necessary strengthening. 



> It had a lot to do with it. Climb is a reflection of surplus power. Or the power to weight ratio after the power needed to overcome drag is taken out. Now why did the F4F have such a big a wing? Both take-off and landing requirements for carrier operation at the time. These requirements changed as time went on. But in 1939-40 the plane had better land at about the speed of an F4F or the Navy won't buy it. Since this plane is going to weigh about 1 ton more than the F4F it better have a good sized wing. You might be surprised at the difference a few hundred HP can make ( or 1000lbs) to climb in the over 20,000ft area. Navy pilots could tell the difference between F4F-3s, -3As and -4s. All had about the same drag.



You were 'accusing' the F4F as a too heavy, and I've responded specifically about it. Not about all the planes; the weight was surely the issue for all the planes. A plane that is of a later date than the F4F can have better flap system to help with landing speeds, plus slats. The heavy, but more powerful fighter, that would not be hampered with heavy folding wings, fuel armament, was what the Navy wanted. It was able to outperform the F4F, and 'my' fighter was feasible for them to have in 1941. Sure thing that lighter F-3 was outperforming the heavy F-4, ditto vs. 1-stager F-3A.


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## Shortround6 (Sep 13, 2012)

the plane will barely make it for late 1941-early 1942 unless you start work in 1939. 

See this web site for a timeline for the Mustang. 

P-51 Mustang Timeline

Please note that the British were "accepting" the aircraft in Southern California. They still had to get the aircraft to England. Once in England they had to be reassembled ( from ocean voyage) test flown, and issued to a squadron, once the squadron _starts_ receiving aircraft it can _begin_ conversion training of both pilots and ground crew. 
Over 2 years from start of design to first combat operation and this is one of the fastest programs of the war. By the time the first planes see combat about 500 have rolled out the factory door. 

Any R-2800 powered fighter would pretty much follow the same or a longer time line. In 1940 the 5th production R-2800 was delivered in March but only 17 engines were delivered in all of 1940. 

It took roughly (an average) one year from the 5th production example until the 1000th was delivered. 

How many fighters do you want _IN SERVICE_ in the Spring of 1942? The 1000th P-51 was not delivered/accepted at the factory) until Jan 1943.


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## tomo pauk (Sep 13, 2012)

Shortround6 said:


> the plane will barely make it for late 1941-early 1942 unless you start work in 1939.



Agreed.



> See this web site for a timeline for the Mustang.
> 
> P-51 Mustang Timeline
> 
> ...



Thanks; fair points there. 



> Any R-2800 powered fighter would pretty much follow the same or a longer time line. In 1940 the 5th production R-2800 was delivered in March but only 17 engines were delivered in all of 1940.
> It took roughly (an average) one year from the 5th production example until the 1000th was delivered.
> How many fighters do you want _IN SERVICE_ in the Spring of 1942? The 1000th P-51 was not delivered/accepted at the factory) until Jan 1943.



Prior 1942, more than 1700 of R-2800s were delivered. Granted, delivered engine does not mean that an aircraft carrying it is at the front line. I'd go for the figure of 800-900 planes produced during 1941; combat losses make it hard to estimate how many planes would be in service during any time frame.


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## wuzak (Sep 13, 2012)

tomo pauk said:


> Prior 1942, more than 1700 of R-2800s were delivered. Granted, delivered engine does not mean that an aircraft carrying it is at the front line. I'd go for the figure of 800-900 planes produced during 1941; combat losses make it hard to estimate how many planes would be in service during any time frame.



What aircraft used them in that period? The Martin B-26 was one, certainly.


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## davparlr (Sep 13, 2012)

Technically, I see no reason that the AAF could not field a capable R2800 “A” engine fighter in January, 1942, that would outperform or equal both the Fw-190A-3 and the Bf-109F-3 at altitudes up to 15-20k ft. Above 20k ft. competing would be problematic. To accomplish this, several criteria would have to be met. One, the AAF would have to actively desire and pursue such an effort, two, procurement efforts would have to start in early, 1939, about the same time as the B-26 effort, and three, manufacture of the R2800 would have to be well planned in order to not significantly affect the other R2800 programs. Some programs may need to be delayed such as the C-46, which would hurt “The Hump”, but the C-47 was still a very capable transport. Priorities would have to be made. 

This aircraft would be 9-10k lbs weight, somewhere between the Fw-190A-3 and A-5 and could carry four .50 Cals ala F4F, P-51B, F8F. Wing area would be around 200 – 220 sqft. and similar to the Fw-190 in weight and power. It would have been designed to accept the “B” engine, say the dash 8 (Corsair). Designing aircraft to growth is not unusual; I believe the F6F was designed to accept a turbocharger. It would add little to the aerodynamics and slightly to the weight. In fact, one possibility would be to design in adaptability to add fuselage inserts to modify CG like the Fw-190D had to do. The upgraded aircraft could be operational Jan. 1943, almost a year before the P-51B arrived, and provide very good performance to a reasonable altitude. This would provide a better performer than a land based Corsair and could possibly expanded in range to give pretty good escort capability but still not as good as the P-51 did.

I would start with the P-66, a clean aircraft with a amazing similarity to the F4U, and 10-20 mph faster than contemporaries with same engine and good flying qualities. It has some problems but I think just needed development time. Rebuild to fit the R2800 to above requirements.



Shortround6 said:


> You either design a bigger than needed ( and poorer performing) fuselage/airframe to take the two stage installation later or you design a smaller tighter better performing aircraft for the single stage engine


It would probably only be length, which would have little effect on airspeed and some weight, unless, of course you can insert fuselage splices.



> The P-66 Vanguard was a 1941 fighter program that was intended for Sweden that was inherited by the USAAC, Great Britain and finally, China. The P-66 had a mediocre combat record in China and was out of service by 1943.


It was fast and handled well. There were significant problems in China from being in a second class war to second class pilots to second class logistics, even P-40s were delivered without components. No comparison to the well flown and well maintained, but slower and slower climbing F4F-3s. Many contemporary aircraft was having performance trouble with the Japanese at the beginning of the war. It is interesting to note that one of the complaints of the pilots was that it had too high a wing loading, which happened to be less than the Fw-190’s wing loading. Poor advanced thinking and training that also plagued the B-26.


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## wuzak (Sep 13, 2012)

davparlr said:


> This aircraft would be 9-10k lbs weight, somewhere between the Fw-190A-3 and A-5 and could carry four .50 Cals ala F4F, P-51B, F8F. Wing area would be around 200 – 220 sqft. and similar to the Fw-190 in weight and power. It would have been designed to accept the “B” engine, say the dash 8 (Corsair).



The dash 8 was a two stage engine.




davparlr said:


> I believe the F6F was designed to accept a turbocharger.



Don't think so. The F6F was originally designed to use the R-2600, but soon changed to the R-2800, and in production used the R-2800-10, which was the same as the -8, except that one had updraft carbies and the other downdraft carbies.


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## davparlr (Sep 14, 2012)

wuzak said:


> The dash 8 was a two stage engine.


That is why the plane would need to be either more growth space or fuselage inserts. I believe the dash 8 is a "B" engine. This is the engine I meant to have growth to. I should have stated growth for a two stage supercharged "B" engine.




> Don't think so. The F6F was originally designed to use the R-2600, but soon changed to the R-2800, and in production used the R-2800-10, which was the same as the -8, except that one had updraft carbies and the other downdraft carbies.


 

Per wikepedia and other sources:



> Other prototypes in the F6F series included the XF6F-2 (66244) and F6F-3 which was converted to use a turbo-charged Wright R-2600-15, which was later replaced by a turbo-charged Pratt Whitney R-2800-21. The performance proved not to be as good as was expected and the turbo chargers proved to be unreliable on both engines:


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## Shortround6 (Sep 14, 2012)

davparlr said:


> Technically, I see no reason that the AAF could not field a capable R2800 “A” engine fighter in January, 1942, that would outperform or equal both the Fw-190A-3 and the Bf-109F-3 at altitudes up to 15-20k ft. Above 20k ft. competing would be problematic.



While you could, in theory, field a R-2800 "A" engine by Jan 1942 it would be in small numbers, large numbers coming later. This may be OK as the Fw 190 is only available in small numbers. The devil, as always, is in the details. The R-2800-5 offers more power, especially for take off. at 14-16,000ft the difference is some what less, especially when the 801 D engine shows up. 1440hp at 18,700ft? vs 1500hp at 14,000ft. The DiD (devil in details) is that the R-2800 is as big "naked" as the BMW 801 is with cowling. The P&W cowlings were not as advanced as the BMW cowling which means you have more drag. How much more? 
2nd DiD, Fw 190 carried 524liters of internal fuel or 138.5 us gallons or 831lbs. The P-39 carried 120 gallons, the P-40 could hold a bit over 150 gallons internal, the Wildcat went about 144 gallons. The F8F went 185 gallons or 1110lbs of fuel. Some posters in this thread have said 200 US gallons (1200lbs) to 250US gallons for a carrier version (1500lbs) And it is not just the weight of the fuel, some of which will be burned off before combat. It is the weight of the larger tanks and perhaps the the larger structure needed to hold the larger tanks. 140 gallons vs 195 gallons?? Look at standard US 55 gal drum. 
Will the US accept an R-2800 fighter with close to the Fw 190s fuel tankage/range/endurance? 
3rd DiD, wing size. anywhere from about 200sq ft to 270sq ft has been mentioned. The Fw 190 wing was just under 200sq ft. as a rough rule of thumb a 25% larger wing might cost 3% of top speed, every thing being as close to equal as possible. That is a loss of 12mph for the 250sq ft wing? Now maybe you don't need the 250sq ft wing if you keep the fuel down below 185 gallons (F8F had 244 sq ft wing) 
4th DiD. Armament weight. The Fw 190 carried 310kg worth of guns and ammo if it had the MG FF cannon in the outer wings. A P-40E carried 332kg of guns and ammo. Actual armament weight can vary due to weights of mounts, gun chargers, feeds, chutes, ammo boxes and ammo links. Does anybody really think if you present the US Army with an R-2800 powered fighter plane in 1939-40-41 that they are only going to stick four .50 cal guns in it? 
One .50 weighs 29kg. One MG 151/20 weighs 42kg. One round of .50 cal ammo goes about 112grams (give or take depending on bullet). One round of 20 X 82mm ammo goes 183-205 grams depending on projectile. 
Four .50s while usable (many Fw 190s were shot down with such an armament) is definitely _inferior_ to the Fw 190s armament even if you take out the wing 20mm MG FFS. 



davparlr said:


> It would have been designed to accept the “B” engine, say the dash 8 (Corsair).



The "B" engine followed hard on the heels of the "A" and in both the P&W Hartford Factory and at Ford it was like flipping a switch. But this is the single stage "B" engine. 2000hp for take off and 1600hp at 13,500ft. P&W builds 2 in 1941 and then 220 in Jan 1942, "A" production drops from 270 in Nov to 263 in Dec to 49 in Jan and stops. Feb 1942 sees 359 "B" single stage engines built. Ford flipped the switch a few months later. They averaged about 230 "A" engines a month for Jan, Feb, Mar of 1942 while building up to 150 "B"s in March. April sees zero "A"s but 463 "B"s Ford never builds a two stage engine but many of those "B"s go into P-47s. 



davparlr said:


> I would start with the P-66, a clean aircraft with a amazing similarity to the F4U,



only in general outline. Sticking a 2000hp 2400lb engine with a 13 ft propeller on a modified trainer (bit of an exaggeration but the P-66 is to the Vultee trainer series what the Boomerang was to the AT-6) is going to call for a bit more than a little development.


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## Shortround6 (Sep 14, 2012)

Some US production numbers;

Type............................1940...............1941....................1942.................1943

P-40..............................778...............2246....................3854.................4258
P-39...............................13.................926....................1932.................4947
F4F (and FMs).................106................324.....................1470................1537

P-38...............................1..................207.....................1479.................2497
P-51...................................................138......................634.................1710
P-47.....................................................1.......................532.................4428
F4U................................1.............................................178.................2293
F6F................................................................................10..................2547

getting R-2800 powered planes overseas to the Philippines, Singapore, The Dutch East Indies,etc. is going to be near impossible before the Japanese attack. The Flying Tigers P-40s were placed on board ship in June or July of 1941 and went into combat after Pearl harbor. The Summer of 1942 is a much more likely combat debut for such an airplane as evidenced by the first combat use of the Mustang and the use of four squadrons at Deippe in August. 
Now how many months between combat debut and making a real difference in theater? 
Gloster delivered 250 Typhoons between Sept 1941 and June 1942. 
The F4U was "rushed" into service in Jan/Feb 1943. 

The US had a policy of working up units in the US on the combat type they would use in combat _BEFORE_ shipping them overseas. In the case of the P-47s, the first units in the US got the P-47Bs and trained for several months. When ready to ship out they were issued factory fresh P-47Cs and the P-47sBs passed to a new squadron that was forming up. 
Sending new units into combat with untried aircraft is an excellent way to run up enemy scores. Many US aircraft having trouble with their .50 cal guns, not because of any trouble with the guns ( or darn little) but because in peace time training flights the ammo trays had seldom been filled to anywhere near full.WIth full loads the ammo shifted in flight and jammed the guns. Lots of little, relatively easy to fix problems can crop up with any new aircraft, The first few using squadrons are essentially the "beta" testers for the aircraft and help write/rewrite the manuals for later squadrons. 
The "fact" that you might be able to have 2-300 R-2800 "A" powered fighters manufactured by Dec of 1941 doesn't mean that you have 10-15 combat squadrons. 
You have about a 9 month "window" for combat use before the P-47 and F4U start pushing a single stage engine fighter out of the picture.

And what have you given up to get it? 

If you have Vultee make it-------- " France placed an order for 300 V-72s, with deliveries intended to start in October 1940. The fall of France in June 1940 stopped these plans, but at the same time the British Purchasing Commission.... was shopping for a dive bomber for the Royal Air Force, and as it was the only aircraft available, placed an order for 200 V-72s (named Vengeance by Vultee) on 3 July 1940, with orders for a further 100 being placed in December.[3] As Vultee's factory at Downey was already busy building BT-13 Valiant trainers, the aircraft were to be built at the Stinson factory at Nashville,[a] and under license by Northrop at Hawthorne, California.[2]
The first prototype V-72 flew from Vultee's factory at Downey, California on 30 March 1941. The first RAF squadrons (No. 82 and No. 110) received Vengeances in October 1942. The first dive bombing missions against Japanese forces were flown on 19 March 1943.

Australia placed an order for 400 Vengeances as an emergency measure following the outbreak of war in the Pacific,[13] which was met by a mixture of Lend Lease and diversions from the original British orders.[5] While the first Vengeance was delivered to the Royal Australian Air Force (RAAF) in May 1942, the aircraft did not arrive in substantial numbers until April 1943. No 12 squadron of the RAAF was the first RAAF squadron to get the Vengence. No. 12 Squadron began to be re-equipped with Vultee Vengeance dive bombers from October 1942."

Now The British may have changed their minds (waffled) about deploying the Vengeance in Europe or the Middle East and delayed things a bit, But it looks like having Vultee build the R-2800 "A" fighter gets it to the squadrons in late summer of 1942 at best and into combat in the fall. 

Sorry guys, but I don't think the performance, while better tha a P-40 or P-39 is in the equal of the Fw 190 and I don't think it would see significant action until the fall/winter of 1942.


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## wuzak (Sep 14, 2012)

davparlr said:


> Per wikepedia and other sources:
> 
> 
> 
> > Other prototypes in the F6F series included the XF6F-2 (66244) and F6F-3 which was _*converted*_ to use a turbo-charged Wright R-2600-15, which was later replaced by a turbo-charged Pratt Whitney R-2800-21. The performance proved not to be as good as was expected and the turbo chargers proved to be unreliable on both engines:



Key word is _*converted*_. Not designed.


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## davparlr (Sep 15, 2012)

Shortround6 said:


> While you could, in theory, field a R-2800 "A" engine by Jan 1942 it would be in small numbers, large numbers coming later. This may be OK as the Fw 190 is only available in small numbers. The devil, as always, is in the details. The R-2800-5 offers more power, especially for take off. at 14-16,000ft the difference is some what less, especially when the 801 D engine shows up. 1440hp at 18,700ft? vs 1500hp at 14,000ft.


No argument here and not incompatible with what I said.


> The DiD (devil in details) is that the R-2800 is as big "naked" as the BMW 801 is with cowling. The P&W cowlings were not as advanced as the BMW cowling which means you have more drag. How much more?


I need to see some data here. With photographs and my trusty scale the comparison between the cowlings F4U and the Fw-190 does not indicate a large difference in cowling diameter beyond the diameter of the engines, 51” for the BMW and 53” for the P&W. Admittedly that is eyeballing it with associated error, but enough question to request specific data.



> 2nd DiD, Fw 190 carried 524liters of internal fuel or 138.5 us gallons or 831lbs. The P-39 carried 120 gallons, the P-40 could hold a bit over 150 gallons internal, the Wildcat went about 144 gallons. The F8F went 185 gallons or 1110lbs of fuel. Some posters in this thread have said 200 US gallons (1200lbs) to 250US gallons for a carrier version (1500lbs) And it is not just the weight of the fuel, some of which will be burned off before combat. It is the weight of the larger tanks and perhaps the the larger structure needed to hold the larger tanks. 140 gallons vs 195 gallons?? Look at standard US 55 gal drum.
> Will the US accept an R-2800 fighter with close to the Fw 190s fuel tankage/range/endurance?


I don’t see fuel as an issue. The F4U carried 237 gallons in the fuselage. No, the AAF would not accept the limited performances used in the German and British aircraft, but it is always a tradeoff.



> 3rd DiD, wing size. anywhere from about 200sq ft to 270sq ft has been mentioned. The Fw 190 wing was just under 200sq ft. as a rough rule of thumb a 25% larger wing might cost 3% of top speed, every thing being as close to equal as possible. That is a loss of 12mph for the 250sq ft wing? Now maybe you don't need the 250sq ft wing if you keep the fuel down below 185 gallons (F8F had 244 sq ft wing)


I don’t see the issue you here. The Fw-190A-5 grossed out at 10k+ with a wing area of 197 sqft. The Ta-152C grossed out at almost 12k lbs and had a wing area of 210 sqft. It depends on what you want to do with the plane.


> 4th DiD. Armament weight. The Fw 190 carried 310kg worth of guns and ammo if it had the MG FF cannon in the outer wings. A P-40E carried 332kg of guns and ammo. Actual armament weight can vary due to weights of mounts, gun chargers, feeds, chutes, ammo boxes and ammo links. Does anybody really think if you present the US Army with an R-2800 powered fighter plane in 1939-40-41 that they are only going to stick four .50 cal guns in it?


Probably not. But I don’t see the issue here. It depends on what the AAF wants to do with the aircraft. If they want the best performance, they could lighten the load. It is the trade off every aircraft designer had to make.


> only in general outline. Sticking a 2000hp 2400lb engine with a 13 ft propeller on a modified trainer (bit of an exaggeration but the P-66 is to the Vultee trainer series what the Boomerang was to the AT-6) is going to call for a bit more than a little development.


I am not sure of this comment. It seems to imply that if a fighter design is associated with a trainer the fighter is somehow inferior even if it meets the fighter design requirements. My experience with trainer aircraft is that they tend to be rugged designs to endure continued abuse by student pilots, and were often converted into successful combat designs. The T-38/F-5 family of aircraft is one example that a fighter and a trainer can be successfully made from the same design effort. Other trainers converted to successful combat aircraft were the T-28 and the T-37/A-37. The A-37 even had a more powerful engine.
I don’t think there is any more evidence that the p-66 was a “modified” trainer than there is to say the BT-13 is a “modified” fighter. Rather it seems both had independent design teams.

While you are right that a lot of design effort was required, this was also true with the B-26 in the same time period and it was operational by Jan. 42.



Shortround6 said:


> Sorry guys, but I don't think the performance, while better tha a P-40 or P-39 is in the equal of the Fw 190 and I don't think it would see significant action until the fall/winter of 1942.


I disagree. I believe this fighter could have been fielded near the same time as the similarly powered but more complex B-26. 57 B-26s arrived in Australia February 26, 1942 and commenced training and began operation against Japan in the spring of ’42. In addition, 52 had already been delivered to the British. In June, 1942, four B-26s ran operations against the Japanese at Midway. If an aircraft as complex and revolutionary as the B-26 could have started development in 1939 and fielded a significant number by Spring, 1942, it is not unreasonable to believe a simpler fighter with similar production emphasis could also be in operations in Pacific in even more significant numbers. This may involve delaying the B-26. But, the B-25 was a reasonably capable replacement for the B-26. 

I agree with you that this version, while having some advantages over contemporary aircraft would not add much. I am not sure that this would have provided much improvement at all over the P-51/A in the same time period. However a two stage version in January, ’43, would have been quite helpful in ETO in operations against the Fw-190A-4/5s and Bf-109Fs and Gs, certainly below 25k, maybe higher, before the P-51Bs showed up.


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## davparlr (Sep 15, 2012)

wuzak said:


> Key word is _*converted*_. Not designed.


However, the installation of a turbosupercharger on a 2600 or 2800 engine is no trivial matter, just look at installation on a P-47. The F6F-2 with the 2600 engine was an early bird and it is unreasonable to doubt that some thought and design decisions went into making this major modification available during development. Just having the excess available space for the turbo and ducting would have been an anathema to aerodynamicist, weights and balances engineer, manufacturing, costs analyst, etc., etc.


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## tomo pauk (Sep 15, 2012)

If I may:



Shortround6 said:


> While you could, in theory, field a R-2800 "A" engine by Jan 1942 it would be in small numbers, large numbers coming later. This may be OK as the Fw 190 is only available in small numbers.



By July 1st 1941, 400+ of the R-2800 were produced. Meaning 400+ of thee fighters deployed overseas by Jan 1942? 



> The devil, as always, is in the details. The R-2800-5 offers more power, especially for take off. at 14-16,000ft the difference is some what less, especially when the 801 D engine shows up. 1440hp at 18,700ft? vs 1500hp at 14,000ft.



The devil is, indeed, in details. The BMW-801D was restricted in all ratings, prior late 1942. That means that, eg. 'Notleistung' (3 min rating) was allowed to be made under 1,35 ata and 2450 rpm ('stead of 1,42 and 2700 rpm), or roughly comparable with 'Steig und kampflesitung'. So no 1440 HP at 18700 ft, but maybe 1320 HP. Sure enough, the things can get interesting for the 190A once the 3 minutes of Notleistung are out; the R-2800 has, ideally, some 12 minutes left to use it's military power (used here for comparison of engine power). 
The power deficit under 15000 ft is 150-300 HP vs. the A series, and, under 13500 ft, is 250-450 HP vs the B series. Only above 17000 ft the restricted 801D equals the 1 stage R-2800s.



> The DiD (devil in details) is that the R-2800 is as big "naked" as the BMW 801 is with cowling. The P&W cowlings were not as advanced as the BMW cowling which means you have more drag. How much more?



Fair points.



> 2nd DiD, Fw 190 carried 524liters of internal fuel or 138.5 us gallons or 831lbs. The P-39 carried 120 gallons, the P-40 could hold a bit over 150 gallons internal, the Wildcat went about 144 gallons. The F8F went 185 gallons or 1110lbs of fuel. Some posters in this thread have said 200 US gallons (1200lbs) to 250US gallons for a carrier version (1500lbs) And it is not just the weight of the fuel, some of which will be burned off before combat. It is the weight of the larger tanks and perhaps the the larger structure needed to hold the larger tanks. 140 gallons vs 195 gallons?? Look at standard US 55 gal drum.
> Will the US accept an R-2800 fighter with close to the Fw 190s fuel tankage/range/endurance?



No quarrels about the fuel situation it's repercussions. US doctrine 'orders' it's fighter force to go out kill. The defender (say, Fw-190 on Western front, from mid 1941 on) is the one that need to climb fast, not the attacker, already at 15-20000 ft. The 1/4 larger wing is there to help with wing loading - that being more favorable than with P-51D. Also, the Fw-190A5 at 8800 lbs (loaded, clean) with wing of just under 200 sq ft and a single stage engine does not direct us toward a great above-20000 ft fighter?



> 3rd DiD, wing size. anywhere from about 200sq ft to 270sq ft has been mentioned. The Fw 190 wing was just under 200sq ft. as a rough rule of thumb a 25% larger wing might cost 3% of top speed, every thing being as close to equal as possible. That is a loss of 12mph for the 250sq ft wing? Now maybe you don't need the 250sq ft wing if you keep the fuel down below 185 gallons (F8F had 244 sq ft wing)



How well was the Fw-190A served by it's wing? Great for combats under 15000 ft (low drag due to size, NOT shape), but offering unfavorable wing loadings above 20000 ft? The R-2800 fighter need thinner wing, something between Spitfire's and Tempest's. We do not want another Typhoon wing mistake here, nor there is the need for the huge wings of the USN birds.



> 4th DiD. Armament weight. The Fw 190 carried 310kg worth of guns and ammo if it had the MG FF cannon in the outer wings. A P-40E carried 332kg of guns and ammo. Actual armament weight can vary due to weights of mounts, gun chargers, feeds, chutes, ammo boxes and ammo links.
> Does anybody really think if you present the US Army with an R-2800 powered fighter plane in 1939-40-41 that they are only going to stick four .50 cal guns in it? One .50 weighs 29kg. One MG 151/20 weighs 42kg. One round of .50 cal ammo goes about 112grams (give or take depending on bullet). One round of 20 X 82mm ammo goes 183-205 grams depending on projectile.
> Four .50s while usable (many Fw 190s were shot down with such an armament) is definitely _inferior_ to the Fw 190s armament even if you take out the wing 20mm MG FFS.



6 HMGs for me, thanks  



> The "B" engine followed hard on the heels of the "A" and in both the P&W Hartford Factory and at Ford it was like flipping a switch. But this is the single stage "B" engine. 2000hp for take off and 1600hp at 13,500ft. P&W builds 2 in 1941 and then 220 in Jan 1942, "A" production drops from 270 in Nov to 263 in Dec to 49 in Jan and stops. Feb 1942 sees 359 "B" single stage engines built. Ford flipped the switch a few months later. They averaged about 230 "A" engines a month for Jan, Feb, Mar of 1942 while building up to 150 "B"s in March. April sees zero "A"s but 463 "B"s Ford never builds a two stage engine but many of those "B"s go into P-47s.



Thanks for the info. Some 11000 of the R-2800s produced in 1942?


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## Shortround6 (Sep 15, 2012)

On the power issue. BMW information from the 1946 "Jane's" corrections welcome. followed by information from an article in Nov/ and Dec 1942 editions of "Aviation Magazine". Article available at the AEHS website. of P&W information from company Data sheets at the AEHS website.

BMW 801C take off and sea level emergency power 1600hp/2700rpm/1.32AtA. 1380hp/2700rpm/1.3AtA at 15,100ft. 
Climbing power, 1460hp/2400rpm/1.25 at sea level. 1310hp/2300rpm/1.25AtA at 14,500ft. 
Max Cruise, 1230hp/2300rpm/1.15AtA at sea level. 1170hp/2300rpm/1.15 ATA at 15,000ft. 

From the magazine, engine report seems to be on a Do 217E engine. Maximum power for takeoff for 3 min. -- 1,580bhp. @ 2,700 rpm. @ 4.7 psi. manifold pressure.
Maximum power (emergency) – 1.585 bhp. @2,550 rpm. @ 15,750 ft. @ 4.5 psi manifold pressure.
Maximum cruising power (continuous) – 1,280bhp. @ 2,300 rpm. @ 18,500 ft. @ 2.2 psi manifold pressure.

Size of engine given as 50in with 52in being the diameter of the cowling. 

"Jane's" numbers for the 801D

T-O and Emergency at sea level. 1700hp/2700rpm/1.42ata. 1440hp/2700rpm/1.42ata/18,70ft. 
Climb power 1500hp/2400rpm/1.32ata sealevel and 1360hp/2400rpm/1.32ata /17,000ft.
Max cruise 1300hp/2300rpm/1.2ata /sea level and 1215hp/2300rpm/1.2ata/18,000ft. 


P&W R-2800-5 (as used in the B-26)
Take off power. 1850hp/2600rpm Military power 1850hp/2600rpm/2700ft and 1500hp/2500rpm/14000ft.
"Normal" Power. 1500hp/2400rpm/7500ft and 1450hp/2400rpm/13,000ft. 
Diameter of engine given as 52.06in. 

The 1944 edition of "Aircraft Engines of the World" has these figures but adds 49in MAP for take-off which seems in line. No other manifold pressures found so far. 

If somebody knows where to find a B-26 manual for the early planes with the -5 engine it would be very helpful. 

Edit> found the manual in the manual section. It does not have a specific engine chart like later manuals. but does give limits of operation. 
Take-off-Auto-rich Low blower only, 2600rpm, 49in M.P. Military power-auto-rich Low blower 2600rpm 49in M.P. High blower 2600rpm 40.5in M.P. 

"B" series R-2800-27 and -31 engines. 
2000hp for take off/2700rpm. Military power 2000hp/2700rpm/1500ft and 1600hp/2500rpm/13500ft.
"Normal" Power. 1600hp/2400rpm/5700ft and 1450hp/2400rpm/13,000ft.

Diameter 52.5 inches. 

From the specific engine chart for a -31 as used in a Lockheed Ventura, as found in the manuals section of this website. 

take off power 2000hp/2700rpm/52in MAP 5 min limit. 
Military power 2000hp/2700rpm/51in MAP 1500ft without RAM and 3500ft with RAM. 
....................1600hp/2700rpm/ 47in MAP 12,000ft without RAM and 13,500ft with RAM, 5 min limit.
Max cont........1600hp/2400rpm/41.5in MAP 5300ft without RAM and 7000ft with RAM.
....................1450hp/2400rpm/42.5in MAP 13,200ft without RAM and 14,500ft with RAM 60 min or no limit. 
Max Cruise......1100hp/2100rpm/32.5in MAP 10,000ft without RAM and 11,500ft with RAM
.....................975hp/2100rpm/30 in MAP 20,000ft without RAM and 21,000ft with RAM
Some of the RAM figures are in red which means not confirmed by flight test. 
Early P-47s had a 5 minute limit on military power, not 15 minutes. So did the early F4Us. 

Makes things a bit closer doesn't it. 

Now the details come in. The difference between a 52in circle and a 54 in circle is 1.15 sq ft. the FW 190 cowling set the world on it's ear when it came to radial engine cowlings. It is doubtful if a US service cowling would be as good in Jan 1942. 
We have been over the fuel, the wing and the armament. Perhaps the US can build a plane that "out performs" the Fw 190 but it won't have any longer range, or a bigger wing or as good as armament. Without the Fw 190 as a goal to aim for would the US restrict themselves to such a small/limited fighter while using their most powerful engine at the start of design in 1939 or 40? 
And if you use more fuel, and a bit bigger wing and six .50s with a decent ammo load you wind up with a bigger heavier plane than the Fw 190 with more drag. DO the above power figures show enough advantage to give the American plane better performance? 

as for the P-66. See Joe Baugher's page. 
Vultee P-66

While the trainers stemmed from work done on the original P-48 fighter project there seems to have been a few trainer parts in the P-48 prototypes. While it may have gotten less credit than it deserves or perhaps the fact that some US users thought it wasn't sturdy enough with the R-1830 engine certainly gives one pause before sticking an R-2800 into it. Basically you need a whole new airplane that just may look a lot like a P-66.

Edit> American propellers may weigh more than the Fw 190 propellers to. I believe the German propellers were wood? Like some British propellers, the same or similar process.


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## tomo pauk (Sep 16, 2012)

Many thanks for the effort of locating typing all the data, the post should be blogged 

There is really not much left to add to the data. 
One thing remain to be 'subtracted' - that the BMW-801D did have it's power settings (not just the Emergency, but also the Climb combat, as well as Max continous) restricted, both in rpm and MAP. The restriction was in force from March 1942 (= in the time of introduction) until late 1942. So the max power at Emergency (Notleistung) setting was 1320 PS @ 17100 ft; the max rating of 1400 PS @ 18700 ft is 'Blocked for the time being' ('Motorleistung zu Zeit gesperrt'). Please take a look here, at the bottom of the table is the engine data for the 801C -D. The table with engine ratings is attached below, confirming the restriction start date ('ab Marz 1942' only values in the brackets are to be used).*

Now on the drag. I have no problems admitting the 190 have had the neatly streamlined installation of an radial engine. What about the wing? At the pg. 338 of the Vees for victory (per German sources), the wing drag at lift coefficient of 0,2 is stated as 0,0089, vs. P-51s 0,0072 - 25% more. Or, the Cd0 of 0,0269 (per RAE testing, original German data welcomed) - fairly comparable with no-finesses USN fighters (F4F, F4U, F6F). My point is that, even with the top notch cowling, the Fw-190 was offering no advantage vs the R-2800 powered fighters. Other point being that a somewhat greater wing (= greater wetted area), but of thinner profile, would offer about the same drag of the wing as it was the case for the 190. Wing of 250 sq ft would offer the wing loading of 40 lbs/sq ft for an 10000 lbs fighter, while the 200 sq ft wing supporting 8800 lbs (= Fw-190A-5) offers 44 lbs/sq ft - 10% greater wing loading for the Fw-190A, making it less than ideal for high altitudes. Where the thin air makes power- and wing-loading far more of a factor than drag.

*added: I've stumbled upon a date when the restrictions were lifted - 12 Oct 1942. The Wiki article draws that information from the 'Jet prop' magazine of Jan 2010.


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## davparlr (Sep 16, 2012)

Shortround6 said:


> Now the details come in. The difference between a 52in circle and a 54 in circle is 1.15 sq ft. the FW 190 cowling set the world on it's ear when it came to radial engine cowlings. It is doubtful if a US service cowling would be as good in Jan 1942.



After some painful research and calculating, I learned that fuselage diameter is only two terms, diameter and swept area (if the diameter of the fuselage increases, the swept area of the fuselage also increases, at least that was my assumption), in Cd0 calculations that also includes wing area, horizontal tail, vertical tail, etc. The source I used, from a site of Daniel Webster University (?), which seems to be a reasonable source, stated that fuselage drag typically made up of about 30% total Cd0. So doing the manipulations they recommended, the impact to Cd0 of the increase in diameter of about two inches is about 1.7% even though the area is actually increased by about 8%. This seems reasonable and does not seem to be a particularly big impact, especially for a 66% increase of hp at SL.
I own up to nothing! 



> Basically you need a whole new airplane that just may look a lot like a P-66.


Yes.
The aerodynamics of the P-66 seems superior to the contemporary R-1830 powered aircraft, P-36C and the XP-41, it was certainly faster, almost as fast as the P-40, and would out-climb it. However all of these aircraft were basically obsolete and the P-66 was late in this effort. If Vultee had stepped up and made the design to support the R2800, they would have made a jump on the competition, however, I am sure they would not have been compliant with the proposal.


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## Shortround6 (Sep 17, 2012)

The whole question of radial engines and drag is up in air. It was a constantly changing area. P&W managed to get a P-40 airframe powered by an R-1830 engine ( I am assuming 2 stage) up to 386mph which is certainly outstanding _*BUT*_ it took until fall (November I believe) of 1942 to do it. Which basically means summer to fall of 1943 before a production would see service. From the picture it appears the aircraft (basically a test mule) was unarmed.

I can certainly agree with the 1.7% increase in drag, once cowlings showed up in the early 30s the frontal area of the engine was always reduced in effect. However for the 1.7% to be valid both cowls have to be of equal design/efficiency. The difference between a P-36 and a P-40 (early) was 22%. Granted the P-40 was liquid cooled but I am trying to work with the same airframe. The P&W test mule may have achieved it's speed at a higher altitude in thinner air, even so it is faster than a P-40F with a Merlin at 20,000ft. 

The question here is were on this curve or path of cowling development would a 1940/41 R-2800 cowling fall? better than the P-36 but not as good as the Fw 190 or P&W experimental cowling ( or later F8F and Fury cowlings)? add the 1.7% to a few percent for not as good a basic design of cowl ( XP-42 went through how many variations and the P-66 itself went through a few) _and_ add in the cooling drag. You are going to need more cubic feet of air going through the cowling to cool an 1850-2000hp engine than a 1600-1700hp one. This is were the big changes in drag for radial engines came from. They had figured out the external shape pretty early. It is the internal airflow/baffling/and exit that changed dramatically. Cowlings like the Fw 190 and F6F and later used the exhaust for two purposes, one was exhaust thrust and the other was to use a flow of air created by the exhaust to suck air through the cowling. The F4U-1 just dumped it's exhaust out the bottom through two pipes. 
Granted cowlings can be "tweaked" as a design progresses even through (or especial through) the prototype stages but I have a hard time seeing service cowlings as good as the Fw's in Dec of 1941 or even the Spring of 1942. 

BTW, I figure the HP advantage of the R-2800 at 15.6-17.6% at sea level depending on models of engines?


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## riacrato (Sep 17, 2012)

Just giving some food for thought:

An Fw 190 powered by an R-2800 actually exists.

_View: https://www.youtube.com/watch?v=XyACmEodRaE_

Doesn't look too gross either, it is a tad fatter (the cowling seems slightly "bulged", especially below). Now I'm well aware this is a civilian thing, not designed to military specifications. They mention cooling problems in the comments to the video (for what it's worth). Still shows an Fw 190 sized airframe apparently takes the bigger engine quite fine and doesn't *look* like a drag monster.





I always thought an R-2600 or R-2800 powered Fw 190 or even La-5 type fighter could've been great. The USAAF or USN simply weren't the customer for such fighters (until Kamikazes and the F8F). The only way I see that happening is if for some reasons large quantities of those engines were shipped to the SU who would then probably have used them either for attackers or adapt the Lavochkin to it. But that's unlikely to happen.


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## tomo pauk (Sep 17, 2012)

Two questions, loosely connected to the topic:
- if some kind soul has original German data about Fw-190A's Cd0, it would be neat if it's posted here
-Dr. Tank said that his fighter is the 'Dienstpferd' (service horse), not the Racing horse. He states further that both Spitfire Bf-109 were 'racing horses' - _a very large engine on the front of the smallest possible airframe; in each case armament had been added almost as an afterthought_. I don't see the Fw-190 being anything but - it was based around the very large engine, that was attached at the smallish airframe, while featuring 4 LMGs as the armament in the 1st iteration. The wing area was at 1st so small that it was upped immediately, even prior the 1st series version; the armament also received prompt increase. So what it was - race or service horse?


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## Shortround6 (Sep 17, 2012)

Without knowing a lot more about the engine installation in the Fw it would be hard to draw any real conclusions. We can speculate a lot. 

1. Which R-2800 is it? A WW II military engine or a post war Commercial engine? In the 50-60s a lot of F4Us and F6Fs were re-engined with ex airliner engines. Easier to maintain, (more parts around) and few war birds really operate at 20,000ft and above anyway so the lack of a two stage supercharger was no big deal. The late war and post war "C" series engines used different cylinders and cylinder heads than the "A" and "B" engines with more fins or fin area which "should" make them easier to cool at lower power levels. 

2. what level of power is this plane using? Full military power? or a lower level of power? this can affect cooling needs. Especially if climate is taken into consideration. Southern California can get pretty hot but as hot as NA or some tropical islands or south east Asia? 

3. what modifications were done to the plane? The original Fw used the leading edge of the cowl as the oil cooler. Is this still being done? 

I have no answers for any of these questions. Without more knowledge of this particular aircraft any guessing from a short video clip doesn't mean much. One also has to wonder how much more knowledge the builder had from DC-6, Martin airliner and Convair airliner installations to help with this rather than being one of the first 2-3 installations made for the R-2800.

EDIT> BTW, hats off and congratulations for the effort into getting this aircraft built and flying.


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## davparlr (Sep 17, 2012)

Shortround6 said:


> BTW, I figure the HP advantage of the R-2800 at 15.6-17.6% at sea level depending on models of engines?


 
Dummy me, I was comparing it to the R-1830!


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## tomo pauk (Sep 18, 2012)

riacrato said:


> ...
> I always thought an R-2600 or R-2800 powered Fw 190 or even La-5 type fighter could've been great. The USAAF or USN simply weren't the customer for such fighters (until Kamikazes and the F8F). The only way I see that happening is if for some reasons large quantities of those engines were shipped to the SU who would then probably have used them either for attackers or adapt the Lavochkin to it. But that's unlikely to happen.



Thanks for the video 

While it would be interesting to discuss the La-5 with R-2800 (hopefully the airframe would've coped well with that), I'm more inclined towards the British fighters with that engine. Say, Spitfire with the 1-stager? 

*ducks for cover*

added: there is data on the Mike Williams' site that confirms the 12. Oct 1942 as the date when the restrictions for the BMW-801D are lifted.


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## Shortround6 (Sep 18, 2012)

Why?

Work it out. Merlin. 45s are available by the time the R-2800-5 is. British don't have time or engineering capacity to even install Merlin XX.


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## riacrato (Sep 18, 2012)

Was that really a problem of time or capacity? I thought that was simply a case of (imo botched) priorities, the engines going to the Hurricane II and other projects instead.


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## Shortround6 (Sep 18, 2012)

According to some the Merlin XX was 4in longer and wouldn't fit easily. The Hurricane needed the XX. To stay in the game at all. Spitfire got the MK XII at about the same time. Merlin 45 is pretty much a XII with a XX supercharger without the 2 speed drive. There is only so much engineering time available (that includes draftsmen making the drawings). Wasting it trying to put a low altitude radial on the Spitfire sure seems like a waste of resources.o


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## riacrato (Sep 18, 2012)

Well I'm no expert on th Spit but like I wrote I only ever heard they had that engine planned for the Hurri (like you say it needed it to stay in the game at all), didn't know of any problems to fit them. I personally think, with or without, in late 1940 the Hurri was out of the game as a fighter (imo), and I'd much rather have a 400 mph Spit III to start into '41.


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## Shortround6 (Sep 18, 2012)

99% of the time Military aircraft were built to fulfill a need. Not because something would look cool or be fun to fly (although those didn't hurt  

It could take Hundreds if not 10s of thousands of hours to engineer an engine "swap" properly and disrupt production for weeks or months. What will the "new" airplane do that the old one won't? Or that the development already in the works won't do? 

The Russians went to radials on the LA-5 because the M-105 engine had hit a wall in development and wasn't going much, if any, further. 
Pretty much the same story (or worse) with the Japanese, they went to the radial because the 1400-1500hp version of the V-12 turned out to have major problems and then earthquake/bomb damage finished off any hope of getting engines at all, no matter how bad. 
Italians went the other way because their production radials had hit walls and the prototypes weren't ready. Too many prototypes with too few engineers. 

The Spitfire was working, engine shortages were not in the emergency category or expected to be long lasting> New Merlins were being worked on with the expectation (fulfilled) that they would work. Why spend thousands of man hours on a bodge up job that will be obsolete in months anyway?


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## tomo pauk (Sep 18, 2012)

Shortround6 said:


> Why?
> 
> Work it out. Merlin. 45s are available by the time the R-2800-5 is. British don't have time or engineering capacity to even install Merlin XX.



Why not? Merlin 45 was inadequate to make Spitfire competitive vs. the 109F-4 and even the troublesome Fw-190s (=prior late 1942). The 1-stage R-2800 turns Spitfire into a 1850 HP machine in 1941, 2000 HP machine in 1942. By the time Germans sort out the 801D, the 2 stage Merlin can get into the fray; the radial remaining in production service. 
As for the British/Supermarine/RR having no time or engineering capacity to install the XX into Spitfire, that's not the serious statement, right? 



riacrato said:


> Was that really a problem of time or capacity? I thought that was simply a case of (imo botched) priorities, the engines going to the Hurricane II and other projects instead.



Agreed. The power egg from Beaufighter, trialed at that Miles fighter, seem like a neat thing to be attached to the Spit. It also ditches the under wing radiator, not a bright spot on the Spit.



Shortround6 said:


> According to some the Merlin XX was 4in longer and wouldn't fit easily.



Yet the 2 stage Merlin could fit? C'mon.



> The Hurricane needed the XX. To stay in the game at all.



Too bad that, by that decision, Spitfire V became 2nd, and then, fast, only the 3rd best fighter in ETO.



> Spitfire got the MK XII at about the same time. Merlin 45 is pretty much a XII with a XX supercharger without the 2 speed drive. There is only so much engineering time available (that includes draftsmen making the drawings).



Yet it was plenty of engineering time to fiddle with Sabre/Typhoon saga? Granted, not the same companies, but the costumer was the same. The hard pressed Soviets managed to find the time to re-engine the Lagg-3, Italians can do it (3 companies at short time), but the British somehow can't pull it?



> Wasting it trying to put a low altitude radial on the Spitfire sure seems like a waste of resources.o



The sentence from above still stands. Making a handful of the Spitfire Mk XIIs seem to imply that there was need to the fighter that can do well under 20000 ft.


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## wuzak (Sep 18, 2012)

tomo pauk said:


> Why not? Merlin 45 was inadequate to make Spitfire competitive vs. the 109F-4 and even the troublesome Fw-190s (=prior late 1942).



Was it inadequate compared to the Bf 109F-4? It was inadequate against the Fw 190s.




tomo pauk said:


> The 1-stage R-2800 turns Spitfire into a 1850 HP machine in 1941, 2000 HP machine in 1942. By the time Germans sort out the 801D, the 2 stage Merlin can get into the fray; the radial remaining in production service.



The Merlin 45 weighed about 1400lb. The R-2800 about 2300lb. Sure, the Spitfire carried a coolant system and radiator which added to the weight, but it would probably not amount to 1/3 of the difference. Also, all the extra weight would be up front, the Spitfire's coolant system's weight isn't all up front.

The R-2800-5 is 6" longer than the Merlin 45 as well. A lot of re-engineering.

The P-51 was 35" wide at the widest point. I believe that the Spitfire was narrower than that. The cowl on the R-2800 would be 54-55" in diameter.




tomo pauk said:


> As for the British/Supermarine/RR having no time or engineering capacity to install the XX into Spitfire, that's not the serious statement, right?



I believe the issue was not enough XXs for both. The Hurricane needed the extra power more. 

Remember also that Supermarines were working on the Griffon Spitfire as well - their first proposal for that engine installation was in 1939. 




tomo pauk said:


> Agreed. The power egg from Beaufighter, trialed at that Miles fighter, seem like a neat thing to be attached to the Spit. It also ditches the under wing radiator, not a bright spot on the Spit.



Aside from making the Spitfire more ugly, you have to ask if it improves the aero any? It certainly has a double whammy effect on weight balance - longer heavier engine up front with a front mounted radiator. It would need some balance weights.




tomo pauk said:


> Too bad that, by that decision, Spitfire V became 2nd, and then, fast, only the 3rd best fighter in ETO.



Behind the Fw 190 and P-51A/Mustang I?




tomo pauk said:


> Yet it was plenty of engineering time to fiddle with Sabre/Typhoon saga? Granted, not the same companies, but the costumer was the same. The hard pressed Soviets managed to find the time to re-engine the Lagg-3, Italians can do it (3 companies at short time), but the British somehow can't pull it?
> 
> The sentence from above still stands. Making a handful of the Spitfire Mk XIIs seem to imply that there was need to the fighter that can do well under 20000 ft.



The problem here is timing. The Griffon Spit was in the works _before_ the Fw 190 appeared. The Merlin 61 was already bench testing when the Fw 190 appeared, and had already been slated for the Spitfire - and probably why the work on installing a Merlin XX was stopped. The R-2800 Spitfire would not, I'm sure, be available before the Spitfire IX (mid 1942) or the XII (late 1942) and wouldn't have the performance of either.


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## davparlr (Sep 18, 2012)

Shortround6 said:


> The question here is were on this curve or path of cowling development would a 1940/41 R-2800 cowling fall? better than the P-36 but not as good as the Fw 190 or P&W experimental cowling ( or later F8F and Fury cowlings)? add the 1.7% to a few percent for not as good a basic design of cowl ( XP-42 went through how many variations and the P-66 itself went through a few) _and_ add in the cooling drag. You are going to need more cubic feet of air going through the cowling to cool an 1850-2000hp engine than a 1600-1700hp one. This is were the big changes in drag for radial engines came from. They had figured out the external shape pretty early. It is the internal airflow/baffling/and exit that changed dramatically. Cowlings like the Fw 190 and F6F and later used the exhaust for two purposes, one was exhaust thrust and the other was to use a flow of air created by the exhaust to suck air through the cowling. The F4U-1 just dumped it's exhaust out the bottom through two pipes.
> Granted cowlings can be "tweaked" as a design progresses even through (or especial through) the prototype stages but I have a hard time seeing service cowlings as good as the Fw's in Dec of 1941 or even the Spring of 1942.


I am not sure this argument comes through in application. The Fw-190A with the 801D engine was capable of doing 330-340 mph at SL with 1700-1800 hp. The contemporary F4U-1, was capable to doing 350 mph at SL with 2000 hp. The F4U is about 2000 lb heavier than the Fw-190 and has 50% more wing area. It seems the the more efficient cowling design, if it existed, helped little to overall aircraft efficiency.


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## Shortround6 (Sep 18, 2012)

tomo pauk said:


> Why not? Merlin 45 was inadequate to make Spitfire competitive vs. the 109F-4 and even the troublesome Fw-190s (=prior late 1942). The 1-stage R-2800 turns Spitfire into a 1850 HP machine in 1941, 2000 HP machine in 1942. By the time Germans sort out the 801D, the 2 stage Merlin can get into the fray; the radial remaining in production service.
> As for the British/Supermarine/RR having no time or engineering capacity to install the XX into Spitfire, that's not the serious statement, right?



You keep keying off the take-off power. The power at combat heights was much different. The Merlin 45 was good for 1230hp at 18,000ft at 12lb boost. What was the R-2800-5 good for at that altitude? Under 1400hp? We are going round and round on the radial engine drag. We know that the P-36 had 22% more than the P-40. even if the FAT-fire has only 14% more drag than a normal Spitfire ( a 1/3 improvement for a even bigger engine) you are down to the power/drag of the Spitfire V. When the British clear the Merlin 45 for 16lb of boost it makes about 1500hp at 11,000ft. A little down from the P&W "A" but then the MK V has a lot less drag. The British aren't really interested in under 10,000ft fighters at the end of 1940 and most of 1941. 

I don't know why they couldn't get the XX engine into a Spitfire easily but Edger Brooks keeps saying they couldn't without a lot of rework. Engineering changes and time are not just stuffing one engine into one airframe but designing and building the jigs and fixtures needed to make the parts in an interchangeable manner rather than "filing to fit" which is the cheapest fastest way to build one or two aircraft. A lousy way to build several hundred. 





tomo pauk said:


> Agreed. The power egg from Beaufighter, trialed at that Miles fighter, seem like a neat thing to be attached to the Spit. It also ditches the under wing radiator, not a bright spot on the Spit.


That "not a bright spot" on the Spitfire may have been one of the "secrets" ( purely unintentional ?) of it's ability to be upgraded. As they added heavier engines in front of the center of gravity the added bigger radiators, oil coolers, and finally inter coolers behind the center of gravity. I am sure it didn't balance out exactly but it sure made things a lot easier than adding ALL the weight on one side of the CG. 





tomo pauk said:


> Yet it was plenty of engineering time to fiddle with Sabre/Typhoon saga? Granted, not the same companies, but the costumer was the same. The hard pressed Soviets managed to find the time to re-engine the Lagg-3, Italians can do it (3 companies at short time), but the British somehow can't pull it?



Russians, or more properly the Lagg "team" didn't have much choice. Either get the LA-5 going or stop production of the Lagg-3 and start building Yaks. 
British were pulling it off, as noted they had been working on alternative engine installations already. How many different engine installations do you want them to work on at the same time? 
And it isn't just a question of doing it at all, it is a question of doing it fast enough to actually do some good. 
July 1939, sees the Italian air force request the Reggiane company install a DB 601 in a Re.2000. Not to be left out Aeronautica Macchi import a DB 601 engine and started work in Jan 1940, they get a prototype flying in August 1940, (not bad) and as a result of good flight tests is ordered into production. First production example roles out in March 1941, (14-15 months after start) first issue to Squadrons in May-June. 1941. 17-18 Months after start. 
When do the British get the bright idea of sticking an R-2800 in a Spitfire to be in service in early 1942? If they can pull it off, what else doesn't get done? 





tomo pauk said:


> The sentence from above still stands. Making a handful of the Spitfire Mk XIIs seem to imply that there was need to the fighter that can do well under 20000 ft.



There may be a need for a fighter that can do well under 20,000ft. An R-2800 powered Spitfire is not it. By the time you are done you have a new plane. You need the wing tanks from the MK VIII, A rear tank of some sort, different propeller, or late model 4 blade/5 blade several years early and/or new landing gear. You need the bigger tail, you may need to raise the cockpit so the pilot can see over the engine. And so on....


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## tomo pauk (Sep 19, 2012)

wuzak said:


> Was it inadequate compared to the Bf 109F-4? It was inadequate against the Fw 190s.



When the Notlesitung for the DB-601E was allowed (start of 1942), it was inadequate.



> The Merlin 45 weighed about 1400lb. The R-2800 about 2300lb. Sure, the Spitfire carried a coolant system and radiator which added to the weight, but it would probably not amount to 1/3 of the difference. Also, all the extra weight would be up front, the Spitfire's coolant system's weight isn't all up front.
> The R-2800-5 is 6" longer than the Merlin 45 as well. A lot of re-engineering.
> The P-51 was 35" wide at the widest point. I believe that the Spitfire was narrower than that. The cowl on the R-2800 would be 54-55" in diameter.



Could we say that the engineers would take the challenge with vigor determination? 



> I believe the issue was not enough XXs for both. The Hurricane needed the extra power more.



Agreed that XXs were not in wide supply, at least not in the 1st year of the production (late 1940 - late 1941). Seem like BC got the lion share of the XXs, not the Hurricane? 



> Remember also that Supermarines were working on the Griffon Spitfire as well - their first proposal for that engine installation was in 1939.



Agreed.



> Aside from making the Spitfire more ugly, you have to ask if it improves the aero any? It certainly has a double whammy effect on weight balance - longer heavier engine up front with a front mounted radiator. It would need some balance weights.



It would also make RAF operating the fighter capable for anything Typhoon can do, say, half a year earlier?



> Behind the Fw 190 and P-51A/Mustang I?



IMO both 190 109 were better, in 1942. The P-51 and Typhoon were better under 15-20000 ft, the P-38F becoming a strong contender, too.



> The problem here is timing. The Griffon Spit was in the works _before_ the Fw 190 appeared. The Merlin 61 was already bench testing when the Fw 190 appeared, and had already been slated for the Spitfire - and probably why the work on installing a Merlin XX was stopped. The R-2800 Spitfire would not, I'm sure, be available before the Spitfire IX (mid 1942) or the XII (late 1942) and wouldn't have the performance of either.



The timing is the advantage, not the problem. With development work starting early enough, the FAT-fire can have it's R-2800s on board in mid 1941 (assuming, of course, that UK can get those prior the USAAF/USN), and be ready for the arrival of the Fw-190. The performance equal to, again, the Typhoon?



Shortround6 said:


> You keep keying off the take-off power. The power at combat heights was much different. The Merlin 45 was good for 1230hp at 18,000ft at 12lb boost. What was the R-2800-5 good for at that altitude? Under 1400hp?



Could you please re-check you numbers? The colored chart I have (and posted it once at the forum) about the Merlins shows 1250 HP at 14000 ft (1050-1100 at 20000 ft), vs. 1500 HP at 14000 ft (1250 at 20000 ft) for the R-2800. 



> We are going round and round on the radial engine drag. We know that the P-36 had 22% more than the P-40. even if the FAT-fire has only 14% more drag than a normal Spitfire ( a 1/3 improvement for a even bigger engine) you are down to the power/drag of the Spitfire V. When the British clear the Merlin 45 for 16lb of boost it makes about 1500hp at 11,000ft. A little down from the P&W "A" but then the MK V has a lot less drag. The British aren't really interested in under 10,000ft fighters at the end of 1940 and most of 1941.



When British clear the M 45 for the +16 psi boost, the 1942 is on the end (tests being done in late 1942, per WIlliams' site). By that time, the FAT-fire has played it's role, and can soldier on as a preferred under-18000 ft fighter. Saying that a Fatfire is an under-10000 ft fighter is a little too much, more so when comparing with what was historically fielded in the 1st half of the war.



> I don't know why they couldn't get the XX engine into a Spitfire easily but Edger Brooks keeps saying they couldn't without a lot of rework. Engineering changes and time are not just stuffing one engine into one airframe but designing and building the jigs and fixtures needed to make the parts in an interchangeable manner rather than "filing to fit" which is the cheapest fastest way to build one or two aircraft. A lousy way to build several hundred.


 
No point in keying off the perceived inability of the Supermarine to attach the XX at the Spitfire - it was being done in Spit III, and later the 3 different, larger and heavier engines were also installed. 



> That "not a bright spot" on the Spitfire may have been one of the "secrets" ( purely unintentional ?) of it's ability to be upgraded. As they added heavier engines in front of the center of gravity the added bigger radiators, oil coolers, and finally inter coolers behind the center of gravity. I am sure it didn't balance out exactly but it sure made things a lot easier than adding ALL the weight on one side of the CG.


 
One thing is location, the other thing is layout. The layout (mounting the radiator box under the boundary layer passage, or installation of the boundary layer splitter) could have been altered, at least once the Bf-109F has being examined. Changing the location serves the same purpose, like what was done from the prototypes of the Typhoon and P-40 towards the serial planes.



> Russians, or more properly the Lagg "team" didn't have much choice. Either get the LA-5 going or stop production of the Lagg-3 and start building Yaks.
> British were pulling it off, as noted they had been working on alternative engine installations already. How many different engine installations do you want them to work on at the same time?
> And it isn't just a question of doing it at all, it is a question of doing it fast enough to actually do some good.



British were pulling it off, the problem was that the fruits of their efforts were rather belatedly installed into the Spitfires - hence the R-2800 to boost the performence, even if that boost is only felt under 15000 ft. 



> July 1939, sees the Italian air force request the Reggiane company install a DB 601 in a Re.2000. Not to be left out Aeronautica Macchi import a DB 601 engine and started work in Jan 1940, they get a prototype flying in August 1940, (not bad) and as a result of good flight tests is ordered into production. First production example roles out in March 1941, (14-15 months after start) first issue to Squadrons in May-June. 1941. 17-18 Months after start.



Thanks.



> When do the British get the bright idea of sticking an R-2800 in a Spitfire to be in service in early 1942? If they can pull it off, what else doesn't get done?



Once they hear about the Typhoon it's projected performance figures?




> There may be a need for a fighter that can do well under 20,000ft. An R-2800 powered Spitfire is not it. By the time you are done you have a new plane. You need the wing tanks from the MK VIII, A rear tank of some sort, different propeller, or late model 4 blade/5 blade several years early and/or new landing gear. You need the bigger tail, you may need to raise the cockpit so the pilot can see over the engine. And so on....



I agree that the rework would've involved considerable changes. The gains would be comparable, too.


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## Vincenzo (Sep 19, 2012)

tomo pauk said:


> When the Notlesitung for the DB-601E was allowed (start of 1942), it was inadequate.



also before the Spit V is not a good place for fight a Friederich-4.

only the Anton-0 had 4 lmg and were not designed for combat, they were trials planes


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## tomo pauk (Sep 23, 2012)

Thanks for the assessment, Vincenzo. IMO, the performance difference between the F-4 (with 'Notleistung' blocked) and Mk.V was not so big? As to the A-0 being a trial plane, well, putting your gold-worth experienced pilots into a plane that is only partly combat suitable is/was not very wise.

The German take on light planes carrying heavy powerful radials: the Bf-109V-21, or maybe Bf-109X? Pictures can be found easily, this page might be a good start:
Messerschmitt Me 209 II V5


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## Shortround6 (Sep 23, 2012)

tomo pauk said:


> The German take on light planes carrying heavy powerful radials: the Bf-109V-21, or maybe Bf-109X? Pictures can be found easily, this page might be a good start:



I believe the Bf-109V-21 used a P&W R-1830. Heavy powerful radial ????


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## Vincenzo (Sep 23, 2012)

tomo pauk said:


> Thanks for the assessment, Vincenzo. IMO, the performance difference between the F-4 (with 'Notleistung' blocked) and Mk.V was not so big? As to the A-0 being a trial plane, well, putting your gold-worth experienced pilots into a plane that is only partly combat suitable is/was not very wise.



i've not understand if you are joking

the Anton-0 were not used in combat unit

Friederich-4 max speed FTH 391 mph Vs 374 mph no large difference (but the Spit has only 5 minutes power). Just looking for data on climb but i don't find for F-4 i try again tomorrow (i know there is some on this forum)


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## tomo pauk (Sep 24, 2012)

Thanks, I stand corrected.



Shortround6 said:


> I believe the Bf-109V-21 used a P&W R-1830. Heavy powerful radial ????



Doh 
The 109X was using the BMW-801, though.


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## johnbr (Sep 24, 2012)

They built two of them one with the PW and one with the BMW.


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## tomo pauk (Sep 30, 2012)

Shortround6 said:


> On the power issue. BMW information from the 1946 "Jane's" corrections welcome. followed by information from an article in Nov/ and Dec 1942 editions of "Aviation Magazine". Article available at the AEHS website. of P&W information from company Data sheets at the AEHS website.
> 
> BMW 801C take off and sea level emergency power 1600hp/2700rpm/1.32AtA. 1380hp/2700rpm/1.3AtA at 15,100ft.
> Climbing power, 1460hp/2400rpm/1.25 at sea level. 1310hp/2300rpm/1.25AtA at 14,500ft.
> ...



Hi, SR6, I'd like to return to the data about the 801C. 
The Max cruising power, going by the data from the magazine, seems to be higher for the -C than for the -D, and at higher altitude, too. The Emergency power of the 801C is also way out of the chart, more appropriate to the overboosted 801Ds (1,65 ata, from late 1943/ early 1944). I know that you were just typing the available data, but it seem to me that the data from the magazine is dubious, to say at least. 
Plus, seem like that Do-217 was never equipped with 801C, but only with -A, -D and -L variants; I'm looking forward to be educated on this, BTW.


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## Shortround6 (Sep 30, 2012)

You may very well be right but I am not liking the numbers for "Jane's" either. Look at the Emergency power and climbing power. 400 more RPM and another 0.07 ata is good for 80 more horsepower 600ft higher? It seems that winding the engine up to 2700rpm wasn't good for much? 

I think the "MAX Cruise" in the magazine was actually the climbing power though  

Not sure how they tested the captured engine.


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## tomo pauk (Sep 30, 2013)

I'd like to get back on this topic, at least to compare what single stage R-2800 was offering. Especially vs. the BMW-801. The more detailed data (about many engines) can be found here.

The chart uses as a basis is for Avenger's engine (R-2600-8, 1700 HP for take off), red are BMWs, blue are single stage R-2800s (A series, as used in early B-26s, and B, as used in later B-26s and war-time A-26s). The A series was produced in 1700+ examples in 1941 (eg. 13 in Jan, 64 in March, 112 in May), the B series follows around Pearl Harbor attack, with 260+ produced in January 1942.

BMW 801C was in use from mid 1941, supplanted in use by Spring of 1942 by 801D. The -D was restricted to 1,32 ata and 2450 rpm until October 1942 (the -C was rated at 1,32 ata and 2700 rpm in low gear, 1,30 ata and 2550 rpm in high gear) - the power in low gear of the -C would be better, with about the same power in high gear, until the -D was cleared for 1,42 ata and 2700 rpm? The -D in graph is for the unrestricted power.

Green square represents the ASh-82, later versions (-F and -FN were able to be over-boosted in lower altitudes). Soviet data gives weight of 780 kg and diameter of 1260 mm (~1720 lbs and 49.6 in), with later versions growing to 900 and 915 kg, respectively. BMW-801 is about 1000+ kg (~2200 lbs), the R-2800 'A' weighting about the same (but of bigger diameter), the 'B' series being about 2300 lbs.


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## Shortround6 (Oct 1, 2013)

I think I got us of topic or crossed threads 

so I am bringing back to this one from the "different Corsair" thread. 

but:



> A-20 stays with the R-1830s, so Martin can use the R-2600s?



Cutting engine power by 25% is going to leave you with some rather reduced capability A-20s. And it might not free up the engines you want.



> The key things are timing and availability. In 1941 USA can install in it's fighters:



This is quite true and key to the situation. 



> -V-1710 'C' series engines, either turbo (1150 HP up to 25000 ft), or non-turbo (1040 HP at 13800 ft). Neither -39, nor the engines with 9.6:1 supercharger drive ratio are available (not counting prototypes) before early and late 1942 respectively



Actual not quite right. the -39 was being installed in _production_ aircraft in mid to late 1941. Prototypes had flown in 1940 and orders for hundreds of P-40s with -39 engines had been placed in May of 1940. This is where the "timing and availability" come into play as it could take months if not over a year from the placement of an order to the delivery of the aircraft _at the factory_ with several more weeks/months before the aircraft show up in action. 
The Flying Tiger aircraft were sold to China in Jan 1941, arrived in Rangoon, Burma in June of 1941 and went into action Dec 20th 1941 as a somewhat extreme example.
As of Dec 1 1941 there were 74 P-40Es in the Philippines. 
The First Allison with 9.60 gears was the F6R in 1940 but it didn't get very far, second ( 3rd) were the F14 and E12 of which 54 were built in late 1941 but these are the ones that had trouble with the supercharger gears and had to be rebuilt with 8.80 gears while a new gear housing and gears were worked on for the later F20R engine. We have difference between what was _planed_ and what was deliverable. 



> -R-1830, single stage or turbo


No argument.



> -R-2800 single stage, 'A' series



Only if you kill the B-26



> -Wright engines (R-1820 and R-2600)



R-1820 is available but a bad choice. The R-2600 is available in numbers but that is the 1600hp "A" engine as used in the A-20 and some other aircraft. about 443 of the 1700hp "B" series were built in 1941 (206 in Dec), this is the engine used in the B-25 and it was built in a different factory (except for 147 built in 1942) than the "A" series engine and used a steel crankcase instead of aluminium among other changes. 

Trying for the early R-2800 powered fighter (single stage) without redoing the production schedules of the engines calls for lower powered A-20s, lower powered B-25s and lower powered B-26s ( if any B-26s at all) 



> Comparing a R-2800 from Jan 1941 with V-1710 from late 1942 (full throttle at 15500 ft) is funny, to say at least.



Not so funny, Allison was not only _promising_ the 9.60 gears for Nov/Dec of 1941 they were building small runs of engines and running model/type tests. The supercharger gears failed. Other improvements (like nitrided crankshafts) were incorporated in production engines of other models. 

IF in the summer of 1941 Allison is promising 1125hp at 15,500ft (having first proposed such an engine in 1940) and P&W has built NO "B" seies engines and only 500-600 "A" series engines (let alone actual installed them in aircraft) AND you _expect_ Packard Merlins to start showing up in Dec/Jan (engines were ordered in Sept of 1940) WHEN do you design/work on the R-2800 powered fighter? USAAC had ordered over 700 P-47s with turbo R-2800s in the fall of 1940. 

The timing and availability of the engines does not come out in favor of a "simple, single stage" R-2800 powered fighter. Another thread talks about America having too many types of aircraft. This is a case of trying to design a specialized aircraft to be produced for a very limited amount of time until it is obsolete.


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## tomo pauk (Oct 2, 2013)

Shortround6 said:


> I think I got us of topic or crossed threads







> so I am bringing back to this one from the "different Corsair" thread.
> but:
> Cutting engine power by 25% is going to leave you with some rather reduced capability A-20s. And it might not free up the engines you want.



The B-26 looks like a better way to use R-2600s than A-20, even if they make only 1600 HP at take off.
The Douglas Havoc I was good for 462 mi, with 325 gals and 2080 lbs of bombs; the A-20A was good for 525 mi with 388 gals and 2400 lbs of bombs. So we loose 10% of range, unless 'my' A-20 minus' is outfitted with 350-360 gals?



> Actual not quite right. the -39 was being installed in _production_ aircraft in mid to late 1941. Prototypes had flown in 1940 and orders for hundreds of P-40s with -39 engines had been placed in May of 1940. This is where the "timing and availability" come into play as it could take months if not over a year from the placement of an order to the delivery of the aircraft _at the factory_ with several more weeks/months before the aircraft show up in action.



Agreed, you are right here.
My addition - the -39 engine does not offer anything in performance over the A series R-2800, at any altitude - the A has 40% more power above 14000 ft.



> The Flying Tiger aircraft were sold to China in Jan 1941, arrived in Rangoon, Burma in June of 1941 and went into action Dec 20th 1941 as a somewhat extreme example.



Yep, they gave a good account with 'sharp nosed' Curtiss.



> As of Dec 1 1941 there were 74 P-40Es in the Philippines.



+1



> The First Allison with 9.60 gears was the F6R in 1940 but it didn't get very far, second ( 3rd) were the F14 and E12 of which 54 were built in late 1941 but these are the ones that had trouble with the supercharger gears and had to be rebuilt with 8.80 gears while a new gear housing and gears were worked on for the later F20R engine. We have difference between what was _planed_ and what was deliverable.



Again, fine points. 
The appeal of the R-2800 is/was that it was actually available, while powerful and reliable.



> Only if you kill the B-26.



Indeed. We might, however, actually build (X)B-28 (even without turbo), once the R-2800 production hits the stride



> R-1820 is available but a bad choice. The R-2600 is available in numbers but that is the 1600hp "A" engine as used in the A-20 and some other aircraft. about 443 of the 1700hp "B" series were built in 1941 (206 in Dec), this is the engine used in the B-25 and it was built in a different factory (except for 147 built in 1942) than the "A" series engine and used a steel crankcase instead of aluminium among other changes.



Agreed. The Wright engines are not the 1st choice for fighters, I've just stated them for completeness sake.



> Trying for the early R-2800 powered fighter (single stage) without redoing the production schedules of the engines calls for lower powered A-20s, lower powered B-25s and lower powered B-26s ( if any B-26s at all).



It also calls for an early US-built fighter that can actually clash with Axis fighters while not suffering too big a performance advantage (while outperforming Japanese fighters, and able to actually climb to kill Japanese 2-engined bombers), that would be available for the Allies from summer of 1941. It calls for a carrier-borne fighter that will do it's task, even if the unexperienced controller puts it 3000 ft under the incoming bomb run, somewhere in South Pacific in 1942. 



> Not so funny, Allison was not only _promising_ the 9.60 gears for Nov/Dec of 1941 they were building small runs of engines and running model/type tests. The supercharger gears failed. Other improvements (like nitrided crankshafts) were incorporated in production engines of other models.
> 
> IF in the summer of 1941 Allison is promising 1125hp at 15,500ft (having first proposed such an engine in 1940) and P&W has built NO "B" seies engines and only 500-600 "A" series engines (let alone actual installed them in aircraft) AND you _expect_ Packard Merlins to start showing up in Dec/Jan (engines were ordered in Sept of 1940) WHEN do you design/work on the R-2800 powered fighter? USAAC had ordered over 700 P-47s with turbo R-2800s in the fall of 1940.



In other words, Allison has only prototypes of the '9.60' engines to promise/show, before mid 1942. In the defense of Allison, the are overtaxed with many versions of their engine, many things will be abandoned or get late.
As for when we should order the fighters - on Feb 1st 1938, the USN holds a design competition for a new fighter, to what Vought proposes a fighter with R-2800 in April 1938. The US Army issued 'Circular Proposal 39-640' in March 1939, to what Martin responded with future B-26. So, the design of the new fighter might commence in 1938. 



> The timing and availability of the engines does not come out in favor of a "simple, single stage" R-2800 powered fighter.



Here we disagree.



> Another thread talks about America having too many types of aircraft. This is a case of trying to design a specialized aircraft to be produced for a very limited amount of time until it is obsolete.



Not a specialized aircraft, neither of a limited time of usability. 
For example, Grumman might decide that there is no much point in developing a fighter that would be only slightly better than F2A, and go for the new P&W engine to power their new fighter. Six HMGs, 200-220 gals, 250-280 sq ft wing. If they keep the wing thickness at 15% (root), it can replace F4F, F6F, F8F (once the 'C' series arrives). Nobody talks about Airabonita anymore, P-60, P-66. The new fighter can be a bomber comparable with Fw-190, F6F and F4U. 
In RAF, CW and VVS use it can offer much more than P-39/40 and F4F.


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## Shortround6 (Oct 2, 2013)

tomo pauk said:


> The B-26 looks like a better way to use R-2600s than A-20, even if they make only 1600 HP at take off.
> The Douglas Havoc I was good for 462 mi, with 325 gals and 2080 lbs of bombs; the A-20A was good for 525 mi with 388 gals and 2400 lbs of bombs. So we loose 10% of range, unless 'my' A-20 minus' is outfitted with 350-360 gals?



The DB-7 had weights of 11,400 pounds empty, 17,031 pounds maximum take-off. top speed 305 mph at 9650 feet with a single speed R-1830, some improvement with better R-1830s could be anticipated. 

Early A-20s had weights of 15,165 pounds empty, 19,750 pounds gross, 20,711 pounds maximum. but the upper weights went to 21,000 pounds gross, 24,500 pounds maximum with the A-20C in early 1941 and late war versions were allowed up to 30,000lb max overload. Top speed went to 340-350mph on the early ones. 





> Agreed, you are right here.
> My addition - the -39 engine does not offer anything in performance over the A series R-2800, at any altitude - the A has 40% more power above 14000 ft.



You are right, it certainly doesn't offer anything in performance _over_ the A series R-2800 *but* the A series R-2800 weighs about 700lbs MORE than a -39 WITH radiator and coolant (and NOT counting the heavier propeller) and if a R-1830 has 22% more drag what does a R-2800 have for drag? The Allison is much easier to get exhaust thrust from ( early F4Us don't _appear_ to use much exhaust thrust) and you _need_ more fuel for the R-2800. An single stage R-2800 "B" can burn 3.5 gallons a minute in Military power at 12,000ft (47") and 4.5 GPM at 2000ft (52") The Allison burns about 2/3rds. Cruise burns are closer. 

A fair amount of the 40% more power is used up in lugging the R-2800 and it's fuel around (fuel system for a F6F's 250gals weighs about 460lbs) and overcoming drag. 

The R-2800 powered plane will perform better, just don't expect anywhere near even 20% better. 



> Yep, they gave a good account with 'sharp nosed' Curtiss.



AS I said, an extreme example but it was almost one year for placement of order for a plane "already in production" AND 'waived' deliveries before they saw action, speaks to "timing and availability" 




> It also calls for an early US-built fighter that can actually clash with Axis fighters while not suffering too big a performance advantage (while outperforming Japanese fighters, and able to actually climb to kill Japanese 2-engined bombers), that would be available for the Allies from summer of 1941. It calls for a carrier-borne fighter that will do it's task, even if the unexperienced controller puts it 3000 ft under the incoming bomb run, somewhere in South Pacific in 1942.



I know what the 'idea' is. In the summer of 1941 P &W was turning out around 100 "A" series engines a month, Allison was building 400-600 engines a month. Things were changing rapidly. January 1941 production was 13 to 130 and in Dec 1941 it was 525 to 1100 but Ford had produced 162 of the R-2800s. 

four .50 cal guns might do for the Japanese 2-engined bombers IF the fighter can get in position and IF the guns actually work. Please plug the two stage R-1830 into the chart, 1000hp at 19,000ft. and note that the single stage R-1830 is about 600-700 lighter, smaller in diameter and uses a smaller propeller and less fuel. 





> In other words, Allison has only prototypes of the '9.60' engines to promise/show, before mid 1942. In the defense of Allison, the are overtaxed with many versions of their engine, many things will be abandoned or get late.
> As for when we should order the fighters - on Feb 1st 1938, the USN holds a design competition for a new fighter, to what Vought proposes a fighter with R-2800 in April 1938. The US Army issued 'Circular Proposal 39-640' in March 1939, to what Martin responded with future B-26. So, the design of the new fighter might commence in 1938.



It might, in fact it would almost have to start design work in 1938/39 to be in production in 1941. Problem is that the US is NOT in a shooting war and the "simple" R-2800 fighter doesn't offer what the either the Navy or the Air Corp _want_. They both want the altitude performance that a 2 stage supercharger brings. The Air Corp _wants_ turbos but knows it can't get them. It 'settles' on the P-39 and P-40 as interim fighters that can be produced in _quantity_ while the _next_ generation of fighters is worked on. The Navy is sliding from the F2A to the F4F and wants the altitude performance the two stage mechanical supercharger "promises", flying examples still aren't working quite right. Buying a successor to the F4F that goes a step backward in altitude performance is probably not going to happen.

Please remember that at this time _NOBODY_ even knows what 100/130 fuel is. They do know what 100/100 fuel is. Promised power outputs 2-4 years ( or 6-7 years for the F8F) down the road have to be looked at with this in mind. They might expect better fuel to become available but since they don't know how to make yet the _when_ is really up in the air. 



> Not a specialized aircraft, neither of a limited time of usability.
> For example, Grumman might decide that there is no much point in developing a fighter that would be only slightly better than F2A, and go for the new P&W engine to power their new fighter. Six HMGs, 200-220 gals, 250-280 sq ft wing. If they keep the wing thickness at 15% (root), it can replace F4F, F6F, F8F (once the 'C' series arrives).



Slight problem in timing here, Grumman built 106 F4Fs in 1940 when only 17 R-2800s were built. Grumman also has hands full designing and building the first TBF. Grumman has a slight problem turning out F4Fs in 1941 too, compounded by P &W inability to deliver two stage engines. 



The F8F is a pipe dream at this point. It needs the "C" series engine which is a totally new engine that just kept the same bore and stroke (1700hp at 16,000ft for the F8F-1), it needs the new supercharger, it needs less fuel and less armament than you are proposing to get it's performance. Try building a 9600lb (gross weight of clean F8F-1) plane in 1940-41 and selling it to the Navy with a 1850hp engine instead of 2100hp for take off and with 50% MORE weight of armament AND 25% more fuel than the 9600lb F8F AND the F8F did NOT meet the NAVY specs for structural strength in place in 1940-41. 

A 1940-41 "F8F" will be heavier and have less power and more drag ( a 1940-41 radial installation NOT at 1943-45 installation) than the 1945 F8F. 

The Navy and Air Corp will STILL WANT the two stage planes for 1943 ( production starting in mid 1942) for performance the single stage engine cannot offer. By mid to late 1942 EVERY 'simple' R-2800 powered fighter built is a P-47 or F4U or F6F NOT built. Hopefully the hundreds or couple of thousand "simple" fighters bought enough of advantage in 1942 that the change over or continued use of the poorer performing "simple" fighters doesn't cause any problems.


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## tomo pauk (Oct 3, 2013)

Shortround6 said:


> The DB-7 had weights of 11,400 pounds empty, 17,031 pounds maximum take-off. top speed 305 mph at 9650 feet with a single speed R-1830, some improvement with better R-1830s could be anticipated.
> 
> Early A-20s had weights of 15,165 pounds empty, 19,750 pounds gross, 20,711 pounds maximum. but the upper weights went to 21,000 pounds gross, 24,500 pounds maximum with the A-20C in early 1941 and late war versions were allowed up to 30,000lb max overload. Top speed went to 340-350mph on the early ones.



Thanks. 
Ray Wagner gives 322 mph @ 15300 ft for the Boston I (Twin Wasp).



> You are right, it certainly doesn't offer anything in performance _over_ the A series R-2800 *but* the A series R-2800 weighs about 700lbs MORE than a -39 WITH radiator and coolant (and NOT counting the heavier propeller) and if a R-1830 has 22% more drag what does a R-2800 have for drag? The Allison is much easier to get exhaust thrust from ( early F4Us don't _appear_ to use much exhaust thrust) and you _need_ more fuel for the R-2800. An single stage R-2800 "B" can burn 3.5 gallons a minute in Military power at 12,000ft (47") and 4.5 GPM at 2000ft (52") The Allison burns about 2/3rds. Cruise burns are closer.



Army R-2800 fighter can do with 200-220 gals and a 250 sq ft wing, 6 HMGs (while not being cursed when carrying them  ), weight does not need to be a pound over what Bearcat weighted. 
Lets see what F4U-1 was capable for: with 1610-1620 HP (normal power) the F4U was making 370+ mph at 16000 ft. The 16000 ft should be the altitude where the R-2800 'A' develops 1500 HP, with ram accounted for (= high speed). The proposed fighter is both lighter, with smaller and thinner wing - that should more than overweight the 7% deficit in power. 
The B series makes 1500 HP at some 1500 ft higher, that should add another 10-12 mph, judging by the same F4F graph (here - thanks, Mike).
At 4000 ft, the F4U does 345 mph with 1800 HP - how much additional 500 HP will do, accompanied with lower drag? 5% more - 360 mph? Versus 290 mph for the F4F. 



> A fair amount of the 40% more power is used up in lugging the R-2800 and it's fuel around (fuel system for a F6F's 250gals weighs about 460lbs) and overcoming drag.



Thanks for pointing out at F6F. A good case of a huge airframe to eat much of the engine's performance, as seen when tested vs. Fw-190.



> The R-2800 powered plane will perform better, just don't expect anywhere near even 20% better.



The 10% increase is okay with me (15% vs. F4F) - 370-380 mph at 16000-17500 ft would be fine for an 1941-42 US built fighter serving abroad. 



> AS I said, an extreme example but it was almost one year for placement of order for a plane "already in production" AND 'waived' deliveries before they saw action, speaks to "timing and availability"
> I know what the 'idea' is. In the summer of 1941 P &W was turning out around 100 "A" series engines a month, Allison was building 400-600 engines a month. Things were changing rapidly. January 1941 production was 13 to 130 and in Dec 1941 it was 525 to 1100 but Ford had produced 162 of the R-2800s.



+1 on that.



> four .50 cal guns might do for the Japanese 2-engined bombers IF the fighter can get in position and IF the guns actually work. Please plug the two stage R-1830 into the chart, 1000hp at 19,000ft. and note that the single stage R-1830 is about 600-700 lighter, smaller in diameter and uses a smaller propeller and less fuel.



For a two stage R-1830 to turn a fighter into a performer, we should devise that fighter that has a 170-180 sq ft wing (and not a too thick one), and, indeed 4 HMGs. How much fuel? 150 gals are fine for the USAF, but for USN? With such armament fuel weight, and once the folding wings are fitted, the wing loading might be too much? What about availability of two stage engines - 1941 sees 3 engines for F4F to have? Once the B series R-2800 is available, it provides 30% more power above 19000 ft, for a small cost in drag, and admittedly, wight. Intercoolers still need space, whole power-plant using similar volume as the single stage R-2800?



> It might, in fact it would almost have to start design work in 1938/39 to be in production in 1941. Problem is that the US is NOT in a shooting war and the "simple" R-2800 fighter doesn't offer what the either the Navy or the Air Corp _want_. They both want the altitude performance that a 2 stage supercharger brings.



Navy (and NACA?) might also tell it's suppliers that really big fighters tend to eat out much of the surplus power the two-stage engines provide.



> The Air Corp _wants_ turbos but knows it can't get them. It 'settles' on the P-39 and P-40 as interim fighters that can be produced in _quantity_ while the _next_ generation of fighters is worked on.



Fair points. 
In the late 1930s many US producers are selling their stuff aboard, a good performing fighter envisioned for foreign costumers should not escape the attention of both Army and Navy officers.



> The Navy is sliding from the F2A to the F4F and wants the altitude performance the two stage mechanical supercharger "promises", flying examples still aren't working quite right. Buying a successor to the F4F that goes a step backward in altitude performance is probably not going to happen.



Stating a F4F as an example for a good hi-alt performance won't cut it. It was managing barely 320 mph at ~18500 ft. FTH in second gear was the same both for static engine and flying airplane (no gain via use of ram effect!) that kills much of the surplus altitude-power of the 2-stage engine. The plane was simply too big and draggy for power installed - 30% more wing area than Fw-190. 



> Please remember that at this time _NOBODY_ even knows what 100/130 fuel is. They do know what 100/100 fuel is. Promised power outputs 2-4 years ( or 6-7 years for the F8F) down the road have to be looked at with this in mind. They might expect better fuel to become available but since they don't know how to make yet the _when_ is really up in the air.



As you can see, I'm not saying a word about overboosting the R-2800; the better fuel will not provide anything at high altitudes anyway.
The extra 100 RPM however, promised by P&W for the 'B' series, were delivered in a timely manner, providing appreciable increase in performance at all altitudes. 



> Slight problem in timing here, Grumman built 106 F4Fs in 1940 when only 17 R-2800s were built. Grumman also has hands full designing and building the first TBF. Grumman has a slight problem turning out F4Fs in 1941 too, compounded by P &W inability to deliver two stage engines.



Fine - the 'big F4F' will be produced from Jan 1941 on, no new engineers will be relocated from TBF design pre-production phase. 



> The F8F is a pipe dream at this point. It needs the "C" series engine which is a totally new engine that just kept the same bore and stroke (1700hp at 16,000ft for the F8F-1), it needs the new supercharger, it needs less fuel and less armament than you are proposing to get it's performance. Try building a 9600lb (gross weight of clean F8F-1) plane in 1940-41 and selling it to the Navy with a 1850hp engine instead of 2100hp for take off and with 50% MORE weight of armament AND 25% more fuel than the 9600lb F8F AND the F8F did NOT meet the NAVY specs for structural strength in place in 1940-41.
> A 1940-41 "F8F" will be heavier and have less power and more drag ( a 1940-41 radial installation NOT at 1943-45 installation) than the 1945 F8F.



I am not trying to build a Bearcat with 1941 technology. When 'C' series is available, it can be installed into the 'big F4F'. In the meantime, P&W can put the effort to improve the current R-2800 installation, like they did with XP-42.



> The Navy and Air Corp will STILL WANT the two stage planes for 1943 ( production starting in mid 1942) for performance the single stage engine cannot offer.



Navy has the F4U in pipeline, Army has the P-47, as historically.



> By mid to late 1942 EVERY 'simple' R-2800 powered fighter built is a P-47 or F4U or F6F NOT built.



Doh. The illed B-26 programme means that 10600 R-2800s are available for single engined fighter using them. The 12300 of the Hellcat's engines are around, too.



> Hopefully the hundreds or couple of thousand "simple" fighters bought enough of advantage in 1942 that the change over or continued use of the poorer performing "simple" fighters doesn't cause any problems.



23 thousands for the whole war, half of them with 2-stage engines after our period of interest?


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## Shortround6 (Oct 3, 2013)

tomo pauk said:


> Army R-2800 fighter can do with 200-220 gals and a 250 sq ft wing, 6 HMGs (while not being cursed when carrying them  ), weight does not need to be a pound over what Bearcat weighted.



You are going to add guns, ammo ? and fuel over and above what the F8F carried and yet the plane won't weigh more? what did you leave out? F8F already had a lower structural strength limit. 




> Lets see what F4U-1 was capable for: with 1610-1620 HP (normal power) the F4U was making 370+ mph at 16000 ft. The 16000 ft should be the altitude where the R-2800 'A' develops 1500 HP, with ram accounted for (= high speed). The proposed fighter is both lighter, with smaller and thinner wing - that should more than overweight the 7% deficit in power.



And the P-40D with 4 guns could make 354mph at 15,175 ft at 7740lbs using 1085hp.
............ P-40E with 6 guns could make 340mph at 15,300ft ft at 8011lbs using 990hp.



> At 4000 ft, the F4U does 345 mph with 1800 HP - how much additional 500 HP will do, accompanied with lower drag? 5% more - 360 mph? Versus 290 mph for the F4F.



An R-2800 powered plane with lower drag than the F4F????
Only if you cook the engine. 




> The 10% increase is okay with me (15% vs. F4F) - 370-380 mph at 16000-17500 ft would be fine for an 1941-42 US built fighter serving abroad.



And the P-40F can do 364mph at at 19,720ft at a gross weight of 8450lbs with bomb rack and sides-way braces installed. 

Or 350-356mph at 18,000ft with any of 5 test propellers installed, no ammo but belly tank shackles and braces.



> What about availability of two stage engines - 1941 sees 3 engines for F4F to have? Once the B series R-2800 is available, it provides 30% more power above 19000 ft, for a small cost in drag, and admittedly, wight. Intercoolers still need space, whole power-plant using similar volume as the single stage R-2800?



Not a small cost in drag, You need a bigger carb intake ( only figures I have is for the Merlin XX in a Hurricane, just over 30hp worth of intake air momentum drag at full speed at 20,000ft) and cooling air pretty much in proportion to power out ( the "C" series R-2800 gets better), And the weight? Better figure close to 1000lbs over the two stage R-1830 by the time you are done. 2270lbs for the "A" series engine. Bigger Prop, bigger engine mount, bigger exhaust, bigger cowl, bigger oil system, etc. 



> Navy (and NACA?) might also tell it's suppliers that really big fighters tend to eat out much of the surplus power the two-stage engines provide.



everything is a trade off, the Two stage engine offers 1650hp 9,000ft higher than the single stage engine. If you want six .50s with 400rpg and a 2400lb engine with a two stage supercharger and range you NEED a big airplane. If you expect to land it on carriers you NEED a big wing. 
You want a small fighter with the big engine pick what you don't want, guns/ammo, range, ability to operate of aircraft carriers. Note that the F8F cut two of those categories in the first model. 



> Stating a F4F as an example for a good hi-alt performance won't cut it. It was managing barely 320 mph at ~18500 ft. FTH in second gear was the same both for static engine and flying airplane (no gain via use of ram effect!) that kills much of the surplus altitude-power of the 2-stage engine. The plane was simply too big and draggy for power installed - 30% more wing area than Fw-190.



Fw -190s don't work real well on carriers. Speed difference at 24-26,000 ft might be a bit closer than picking best altitude for the 190. F4Fs were faster than P-40s up around 25,000ft even if 20-30mph slower at 15,000ft. 
It isn't an example of great hi-alt performance but it is entering production in 1940 with the F4U on the way. 



> As you can see, I'm not saying a word about overboosting the R-2800; the better fuel will not provide anything at high altitudes anyway.



The fuel situation is not about over boosting, it is about what size engines will be needed in the next 2-4 years or what levels of performance can be expected several years down the road. 



> I am not trying to build a Bearcat with 1941 technology. When 'C' series is available, it can be installed into the 'big F4F'. In the meantime, P&W can put the effort to improve the current R-2800 installation, like they did with XP-42.



I am sorry but that sounds exactly like what you are doing. Use a single stage R-2800 engine, use a wing about the same size as the F8F. Except you want to carry more fuel, more armament and have the higher load factor and yet weigh less. Please note that BOTH the USAAC and the NAVY wanted 8 Gs service and 12 Gs ultimate load although landing gear loads or carrier landing loads may have been different. 

Please note that the XP-42 experiments carried on for around two years. 



> Doh. The illed B-26 programme means that 10600 R-2800s are available for single engined fighter using them. The 12300 of the Hellcat's engines are around, too.



Doh, what replaced them? R-1830 powered A-20s? And the single stage fighter, while better than the Japanese fighters, will NOT have the margin of superiority of the F6F. 

Try running your estimates of the F8F. But please note that the "C" series engine in the F8F-1, while it weighed about 100lbs more, had a slightly improved supercharger and the new cylinder cooling fins and cylinder heads allowed for either more power with the same amount of air or the same power with less cooling air. This is in addition to better cowl in general and the better (but not great?) use of exhaust thrust compared to the F4U and F6F.


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## tomo pauk (Oct 4, 2013)

Shortround6 said:


> You are going to add guns, ammo ? and fuel over and above what the F8F carried and yet the plane won't weigh more? what did you leave out? F8F already had a lower structural strength limit.



I leave out carrier suitability. It added 500 lbs (10% of empty weight), Spit V vs. Seafire L. Mk.III. Just having a folding wing was to cost 250-300 lbs, F3F-3 vs FM-2 and F3F-4. 




> And the P-40D with 4 guns could make 354mph at 15,175 ft at 7740lbs using 1085hp.
> ............ P-40E with 6 guns could make 340mph at 15,300ft ft at 8011lbs using 990hp.



Neither was making 370-380 mph, not even when we sacrifice 1/3rd of the firepower. 



> An R-2800 powered plane with lower drag than the F4F????
> Only if you cook the engine.



Think you've misread my sentences there - lower drag than F4*U*, not F4*F*. 



> And the P-40F can do 364mph at at 19,720ft at a gross weight of 8450lbs with bomb rack and sides-way braces installed.
> Or 350-356mph at 18,000ft with any of 5 test propellers installed, no ammo but belly tank shackles and braces.



P-40F has some points against the R-2800 fighter: it does not solve the problem of the Navy MC having a high performance fighter, even of we navalize the P-40F; we need to wait until 1942 to have it; once we have it, it can use 1/3rd of Packard production (~2400 engines in 1942; R-2800 was produced in 11800 examples in 1942, and only USA can will use it - 3/4rs for 'my' fighter?). 




> Not a small cost in drag, You need a bigger carb intake ( only figures I have is for the Merlin XX in a Hurricane, just over 30hp worth of intake air momentum drag at full speed at 20,000ft) and cooling air pretty much in proportion to power out ( the "C" series R-2800 gets better), And the weight? Better figure close to 1000lbs over the two stage R-1830 by the time you are done. 2270lbs for the "A" series engine. Bigger Prop, bigger engine mount, bigger exhaust, bigger cowl, bigger oil system, etc.



I was thinkering of a ~ 10000 lbs Navy fighter, loaded weight. Compared with 8000 lbs for the F4F-4, and 11200 for F4U-1. Cd0 between F4F and F4U (~0.026), on wing area of, say, 280 sq ft should give the f=7.28 sq ft (6.58 for the F4F, 8.38 for the F4U).



> everything is a trade off, the Two stage engine offers 1650hp 9,000ft higher than the single stage engine. If you want six .50s with 400rpg and a 2400lb engine with a two stage supercharger and range you NEED a big airplane. If you expect to land it on carriers you NEED a big wing.
> You want a small fighter with the big engine pick what you don't want, guns/ammo, range, ability to operate of aircraft carriers. Note that the F8F cut two of those categories in the first model.



Fair points. It was pity that Corsair's wing was not thinner (18% at root?), and that Grumman did not installed a smaller thinner wing, but with more up-to-date high-lift devices.



> Fw -190s don't work real well on carriers. Speed difference at 24-26,000 ft might be a bit closer than picking best altitude for the 190.



USN clocked the Fw-190A-4 at 410 mph @ 25000 ft (later A5 and A6 will be down couple of mph, carrying more cannons), the F4F-4 a tad over 300 mph. Despite being a single stage engine, the BMW-801D was providing 380 HP more at about same FTH (18700 ft vs. 18400 for the R-1830), along with greater exhaust thrust. 



> F4Fs were faster than P-40s up around 25,000ft even if 20-30mph slower at 15,000ft.
> It isn't an example of great hi-alt performance but it is entering production in 1940 with the F4U on the way.



Production problems with two stage R-1830s made sure that hi-alt F4Fs were made in penny packets prior 1942. 300 vs. 290 mph is nothing to brag around, especially if the foreign competition is substantially faster (Spit Mk.II making almost 340 mph at 25000 ft). 



> The fuel situation is not about over boosting, it is about what size engines will be needed in the next 2-4 years or what levels of performance can be expected several years down the road.



Agreed. A bigger engine (R-2800) will have more to offer than a smaller engine (R-1830).



> I am sorry but that sounds exactly like what you are doing. Use a single stage R-2800 engine, use a wing about the same size as the F8F. Except you want to carry more fuel, more armament and have the higher load factor and yet weigh less. Please note that BOTH the USAAC and the NAVY wanted 8 Gs service and 12 Gs ultimate load although landing gear loads or carrier landing loads may have been different.



I am not promising 425 mph, neither the great rates of climb Bearcat offered.



> Please note that the XP-42 experiments carried on for around two years.



Thanks. Results of the experimenting should come in handy, say, for 1944, along with water injection.



> Doh, what replaced them? R-1830 powered A-20s? And the single stage fighter, while better than the Japanese fighters, will NOT have the margin of superiority of the F6F.



The Twin Wasp A-20s will be built in lieu of historic A-20s; the B-26 will be replaced with Martin built B-25s. The new fighter will also make a far better bomber than P-39/40, F4F, Spitfire, Hurricane. It will be also available for the VVS, unlike historic R-2800 fighters (bar 200 P-47s delivered). 
F6F possessed a margin of superiority vs. fighters that have had performance good for BoB (Zero, Hayabusa). Vs. Shoki or Hien it was far from being a clear cut advantage. The major shortcoming of F6F was timing, however, not speed. It will not do anything in Allied favor until the war is irreversibly decided.



> Try running your estimates of the F8F. But please note that the "C" series engine in the F8F-1, while it weighed about 100lbs more, had a slightly improved supercharger and the new cylinder cooling fins and cylinder heads allowed for either more power with the same amount of air or the same power with less cooling air. This is in addition to better cowl in general and the better (but not great?) use of exhaust thrust compared to the F4U and F6F.



Comparing with F8F involves far more variables, than vs. F4U. Plus, I do have only the charts for the F8F-2.C


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## Shortround6 (Oct 4, 2013)

> I leave out carrier suitability. It added 500 lbs (10% of empty weight), Spit V vs. Seafire L. Mk.III. Just having a folding wing was to cost 250-300 lbs, F3F-3 vs FM-2 and F3F-4.



we are back to the timing thing. If design work starts in 1938-39-early 40 _is_ Navy buying shore based aircraft? And even if they are can they afford both shore based and carrier based aircraft at the same time? 
_AND_ if you SKIP the F4F what do you use on the carriers? 
We also have an armament problem. The F4F was designed, at some point in it's early History to carry TWO.30 cal guns in the cowl and Two .50 cal guns in the wings. It was also designed without self sealing tanks and no armor. 
F4U was designed with One .30 cal gun in the cowl and one .50 cal gun in the cowl and one in each wing, no protection. 
The .50 gun was also firing at 600rpm at his point in time, changed to 800rpm was at some point in 1940 so _desired_ armament has to be taken into account. Armament was radically changed on later versions. 
F4U is _offering_ close to 400mph, not 370-380, _with_ carrier compatibility, _and_ better high altitude performance than a single stage plane would. 

There was only one prototype F4U and the design was extensively modified for the production version. TWO other factories were brought into the production scheme _before_ the first actual production plane (2nd F4U built) flew. 

The Carrier compatibility proved somewhat elusive but the Navy buying fighters it _KNEW it could not use on carriers_ in 1940? 
Design work on the F6F was actually done in fits and starts and redo's from 1938 with the idea of using the Wright R-2600. It firmed up pretty well in the fall of 1940 (already getting late) with the mock up inspected in Jan 1941, changes were made to the length, wingspan and wing area, all were made larger. Of the two prototypes _ordered_ in the summer of 1941, One was to have a two stage supercharged R-2600 offering 1380hp at 21,500ft. and the 2nd was to use a turbo-charger. Navy appears to be interest in altitude performance. 



> Neither was making 370-380 mph, not even when we sacrifice 1/3rd of the firepower.



True but they are close, or perhaps close enough to hold the line while the F4U with it's 390-400mph speed is brought into production. 



> P-40F has some points against the R-2800 fighter: it does not solve the problem of the Navy MC having a high performance fighter, even of we navalize the P-40F; we need to wait until 1942 to have it; once we have it, it can use 1/3rd of Packard production (~2400 engines in 1942; R-2800 was produced in 11800 examples in 1942, and only USA can will use it - 3/4rs for 'my' fighter?).



But you said you didn't want carrier compatibility? Which is it? 

And carrier compatibility is NOT just a folding wing and a tail hook. It is meeting the take-off, stall and landing requirements, at least until enough shooting has occurred to convince people that a few more landing/take-off accidents are preferable to getting shot out of the sky. But that is way too late to make over a design. 

On the Army side you are facing the whole P-43, P-44, P-47 saga, Army ordered 733 P-47s off the drawing board in Sept 1940. Shoving a 1600-1650lb Twin Hornet into the P-43 instead of the 1450-1500lb R-1830 may not have been that big a deal for the P-44, trying to shove a 2300lb R-2800 into it is a whole new story even if you leave out the turbo. 






> I was thinkering of a ~ 10000 lbs Navy fighter, loaded weight. Compared with 8000 lbs for the F4F-4, and 11200 for F4U-1. Cd0 between F4F and F4U (~0.026), on wing area of, say, 280 sq ft should give the f=7.28 sq ft (6.58 for the F4F, 8.38 for the F4U).



Cutting wing area by 9% or so isn't going to do much on the high end. It was figured that 25% reduction in wing area was only good for a 3% increase in speed. Important in winning a race or gaining/holding a contract with performance penalties but not so important in the real world. 



> Fair points. It was pity that Corsair's wing was not thinner (18% at root?), and that Grumman did not installed a smaller thinner wing, but with more up-to-date high-lift devices.



The high lift devices are not free, they cost weight, fabrication time (money), and often drag. 











Things got better as time went on but the early Fowler flaps had protruding tracks/supports, also notices the fixed slots on the model. The combination _was_ better than using a bigger wing. BTW the landing speed of the Lockheed 14 airliners was given as 65 mph, 8-10mph less than an F4F Wildcat. Cutting the wing area 25% increase stalling speed about 15% as a general rule of thumb, so the Lockheeds high lift devices were worth around 130-140 sq ft of wing. A worthwhile change on the airliner? On a single engine fighter?????



> Production problems with two stage R-1830s made sure that hi-alt F4Fs were made in penny packets prior 1942. 300 vs. 290 mph is nothing to brag around, especially if the foreign competition is substantially faster (Spit Mk.II making almost 340 mph at 25000 ft).



True but KNOWING you are going to have production problems 1-2 years before they happen might mean you could solve them 

The F4F showed the way with two stage superchargers. The whole plane had a number of "problems" in service, which if the designers/users had known in 1939/40 what they knew in 1942/43 might have been changed. Like a number of other early fighters gained an awful lot of weight ( from prototype F4F-3, not XF4F-3) to F4F-4 it gained close 1200lbs (6260lbs to 7406lbs) with NO increase in power. It didn't affect speed that much but played h**l with the climb and altitude performance much like the P-40s. 
The Spitfire is also a rather extreme example. Try comparing to a Hurricane II with the Merlin XX and remember that the F4F is getting little benefit from exhaust thrust (worth around 100hp at 25,000ft to the Hurricane). 




> Thanks. Results of the experimenting should come in handy, say, for 1944, along with water injection.



They are part of the reason the F8F did what it did. It was the beneficiary of 3-4 years worth of knowledge that did not exist in 1939. 
The Problem we are having is how much do you _unwind the clock_ to try to figure what was was possible or likely in a 1941 production plane vs a 1945 production plane. 



> The Twin Wasp A-20s will be built in lieu of historic A-20s; the B-26 will be replaced with Martin built B-25s. The new fighter will also make a far better bomber than P-39/40, F4F, Spitfire, Hurricane. It will be also available for the VVS, unlike historic R-2800 fighters (bar 200 P-47s delivered).



Bostons had such short range that they were almost useless for bombing France or the low countries from bases in England. One reason they were adapted as night fighters, Bomber command couldn't figure out what to do with them 
Maybe the Russians can use them. While the R-2800 fighter would be a better/fighter bomber than the planes you mention that role WOULD NOT be on the minds of the people designing/ordering fighters in 1939/40. This is reward projection. You KNOW what roles fighters were put to use at in the mid and late war years. While the P-47 has quite a reputation as a ground pounder the B model carried NO external stores and the C and early D models carried ONE 500lb bomb on the fuel tank mount. The D-15 models and later had a reinforced wing to take external under wing loads and this was apparently a simple modifications as some older aircraft where modified in the field. BUT it means few, if any, people were contemplating using the P-47 as a "bomber" in 1940-41. 
I am not sure the VVS got ANY R-2800s aside from the ones in P-47s, I don't think they got any B-26s? 




> F6F possessed a margin of superiority vs. fighters that have had performance good for BoB (Zero, Hayabusa). Vs. Shoki or Hien it was far from being a clear cut advantage. The major shortcoming of F6F was timing, however, not speed. It will not do anything in Allied favor until the war is irreversibly decided.



this may be true but it changes very little about the situation in 1939/40. A fighter using a single stage two speed supercharger R-2800 that will not go into production until mid 1941 at best will be viewed as an interim fighter to be used to "hold the line" until the desired fighters (P-38s, P-47s, F4Us and what ever odd balls the the procurement officers were favoring , like XP-55 Ascenders) can be built. Investing millions of dollars in a interim fighter when they already have the P-39, P-40 and F4F as interim fighters may be seen as a waste of resources even if the simple R-2800 fighter does over a margin of improvement over the older fighters. 
And since you stated at the beginning you don't want it to be carrier compatible it does the USN no good. They are stuck with the F4F until the F4U becomes carrier qualified or they get desperate. 




> Comparing with F8F involves far more variables, than vs. F4U. Plus, I do have only the charts for the F8F-2.



Well, it is the right size, and uses the closest engine even if it carries less fuel, less armament and has a better engine installation ( from the cooling, drag, and exhaust thrust) than a 1940-41 plane would have.


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## Conslaw (Oct 5, 2013)

_America's Hundred Thousand_ says that 532 P-47s were produced in 1942 and the Navy took delivery of 178 F4Us in 1942. Only 12 F6Fs were built (10 delivered) in 1942, but more critically, (from one factory) Grumman basically delivered all the F6Fs that the Navy needed for their new fast carriers as fast as the carriers were built and ready for service. This was the case until the Kamikaze threat escalated and more fighters were needed on each carrier, and by this time there was a surplus of F4Us in the pipeline, and the F4U had cured its main problems with carrier landings, so the Corsairs could supplement the Hellcats on the carriers. For none of these aircraft does it seem that problems with the two-stage supercharger (or Turbocharger in the P-47) significantly delayed the aircraft as a whole. 

Let's assume for the sake of argument that a single-stage R2800 fighter would have been available by the Spring of 1942. How would it have affected the war? I believe not much, and the reason is the US didn't lose any major battles from mid 1942 to mid 1943 because of insufficient fighter performance. In the Pacific, at Midway and Guadalcanal, while some pilots complained about F4F performance, as a general rule when the F4Fs were properly vectored out to meet opposing aircraft, they preformed quie well. 

Against the Germans, American air operations were just a token before forces were diverted for the landings in North Africa in November 1942. P-38s and P-40s along with British Spitfires were pretty effective in North Africa. By the time American offensive operations from England got going again in 1943, the P-47s were already coming on line (with range limitations at this point), and in any case, the higher altitude rating of the turbocharged R2800 in the P-47 was needed in the bomber escort role.


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## Shortround6 (Oct 5, 2013)

Courtesy of Krieghund:






Note column 3 of the first chart using "normal" power which is 1700hp from sea level to 8500ft ( a bit low in power for the first 5000ft) and 1500hp from 11700 to 18500ft ( a bit high for the last few thousand feet).

Conditions are with bomb/fuel racks. Clean adds 12-15mph. 

Now what we do know is that the F8F had lower cooling needs than the early P&W R-2800s, less airflow though the cowling.
The F8F made better use of the exhaust gas than the F4U did perhaps as much as 150hp worth? 
Also note the armament of four .50 cal guns with 300rpg. Going to six .50s with 400rpg would add at least 400lbs. 
And the amount of fuel needed. 
General Kennedy complained to General Arnold that the P-40s had more range than the first P-47s to reach the South Pacific. P-40s may have had drop tanks and the P-47 didn't but the P-47 had 305 gallons for their R-2800s. Range/radius in the South Pacific not under the same conditions as Europe.
Note stalling speed _without_ fuel was about 10-12mph higher than a Wildcat or about 10-14mph higher than an F4U without fuel. 
What was acceptable landing behavior in 1944 was different than what was acceptable in 1938-40.


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## tomo pauk (Oct 6, 2013)

Thanks to both of you 

Lets make the assesment of the weight for both USAF ("Army R-2800 fighter can do with 200-220 gals and a 250 sq ft wing, 6 HMGs (while not being cursed when carrying them ), weight does not need to be a pound over what Bearcat weighted.") and USN ("For example, Grumman might decide that there is no much point in developing a fighter that would be only slightly better than F2A, and go for the new P&W engine to power their new fighter. Six HMGs, 200-220 gals, 250-280 sq ft wing." - quotes from my previous posts should point to the intended costumers)fighters.
The combat-ready F8F-1 weighted 9500 lbs, give or take. The lighter engine, prop and no ADI saves us 100+100+100 lbs? Better punch means 400 lbs more, 30 gals of fuel means 200 lbs more (180 lbs of fuel, 20 for greater tank). 100 lbs for tad a bigger wing? That would be some 9900 lbs for the USN fighter; call it 10000 lbs.
Army fighter does not need wing folding (saves 300 lbs?), neither the hook and any fuselage reinforcements that are needed for the every day CV landings (another 100 lbs). Undercarriage is also lighter (100 lbs) because of the same reason. So we're back at 9500 lbs here.



> Now what we do know is that the F8F had lower cooling needs than the early P&W R-2800s, less airflow though the cowling.
> The F8F made better use of the exhaust gas than the F4U did perhaps as much as 150hp worth?



That's what I've had in mind, saying that an assesment based upon the F4U involves less variables - the engine installation is of same generation (as clean/draggy; no exhaust thrust worth speaking about; bad usage of ram effect - 2000 ft vs. 4000 ft for the Bearcat). The higher alt the F8F makes the power ( 18300 ft (Normal setting) vs. 15500 ft (Military setting) for 1500 HP) etc. With F4U it's far easier - it makes 375-380 mph at 17500 ft, using ~1600 HP (with ram). At that altitude 'my' fighter has 1500 HP (B engine), but less weight and drag - upon these data, I have the nerve to say that my fighter will be at least as fast at same 17500 ft. It will be faster than the F4U from SL to 15000 ft, because of more or equal power, with less drag.



> And the amount of fuel needed.
> General Kennedy complained to General Arnold that the P-40s had more range than the first P-47s to reach the South Pacific. P-40s may have had drop tanks and the P-47 didn't but the P-47 had 305 gallons for their R-2800s. Range/radius in the South Pacific not under the same conditions as Europe.



It was July 1943 when. Gen Kenney made his point heard. The fighter entering usage in Spring of 1941 has plenty of time to have the drop tanks attached to it, as it was the case for all the US fighters that mattered - by Jan 1942, the P-38/39/40 and F4F-4 were carrying them. 
The lighter smaller fighter should certainly make better mileage than a really bi one, too.



> Note stalling speed without fuel was about 10-12mph higher than a Wildcat or about 10-14mph higher than an F4U without fuel.
> What was acceptable landing behavior in 1944 was different than what was acceptable in 1938-40.



The plane I proposed should have about the same wing loading as the F4U. The leap in performance vs. F2A should be enough for the Navy to invest 20 more hours of training for it's aviators. 

Hello, Conslaw:



> America's Hundred Thousand says that 532 P-47s were produced in 1942 and the Navy took delivery of 178 F4Us in 1942. Only 12 F6Fs were built (10 delivered) in 1942, but more critically, (from one factory) Grumman basically delivered all the F6Fs that the Navy needed for their new fast carriers as fast as the carriers were built and ready for service. This was the case until the Kamikaze threat escalated and more fighters were needed on each carrier, and by this time there was a surplus of F4Us in the pipeline, and the F4U had cured its main problems with carrier landings, so the Corsairs could supplement the Hellcats on the carriers. For none of these aircraft does it seem that problems with the two-stage supercharger (or Turbocharger in the P-47) significantly delayed the aircraft as a whole.



For either the two-stage or turbo R-2800, both Navy and Army will have to wait until mid 1942 to have some meaningful number of aircraft. Once we allow time for pilots to be trained, planes deployed overseas, steady flow of mechanics spare parts, it's already 1943, and the war is decided at all the fronts (unless the major Allied countries make a series of major blunders). A fighter with single stage R-2800 has a full year of head start, and it can fight in good numbers already in early 1942, if not in late 1941 (N. Africa, Soviet Union) - making it's presence felt. 



> Let's assume for the sake of argument that a single-stage R2800 fighter would have been available by the Spring of 1942. How would it have affected the war? I believe not much, and the reason is the US didn't lose any major battles from mid 1942 to mid 1943 because of insufficient fighter performance. In the Pacific, at Midway and Guadalcanal, while some pilots complained about F4F performance, as a general rule when the F4Fs were properly vectored out to meet opposing aircraft, they preformed quie well.



1st, there were other Allied countries involved (RN can have the easier time during Med convoys, VVS has something to really hurt LW, at least under 15000 ft - where it matters) 
2nd, the better fighter can save the USN a carrier (eg. Lexington, lost at the Battle of Coral Sea - here - due to the (unexperienced?) men at Lexington, the inbound torpedo run was not intercepted at proper height etc; defending SBDs (!) were trashed by Zeroes, so the Vals were able to inflict further damage). Wildcat was crucialy dependent on accurate radar 'picture', and that was not always the case in 1942.
With Lexington available, USN fights Midway battle with 4 carriers, not loosing a single one there? It can push Japanese in Mid Pacific in second half of 1942, not waiting 1943? IJA looses much more men material during the Solomons campaign?



> Against the Germans, American air operations were just a token before forces were diverted for the landings in North Africa in November 1942. P-38s and P-40s along with British Spitfires were pretty effective in North Africa. By the time American offensive operations from England got going again in 1943, the P-47s were already coming on line (with range limitations at this point), and in any case, the higher altitude rating of the turbocharged R2800 in the P-47 was needed in the bomber escort role.



P-40 was roughly handed by LW, even the MC.202 was a better performer. RN/FAA was fighting outnumbered in the MTO until 1942, a boost in the performance of it's fighters might save them much of the British (and American) steel? P-38 was late in the fray with more than token numbers (=1943), with issues of it's own (while having many pluses, of course). Spitfires were being sent into MTO in penny packets prior 1943, leaving the P-40s and Hurricanes to do the job. Those fighters were many times used as fighter bombers, where 'my' fighter would've been far better.


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## Shortround6 (Oct 6, 2013)

tomo pauk said:


> Lets make the assesment of the weight for both USAF ("Army R-2800 fighter can do with 200-220 gals and a 250 sq ft wing, 6 HMGs (while not being cursed when carrying them ), weight does not need to be a pound over what Bearcat weighted.") and USN ("For example, Grumman might decide that there is no much point in developing a fighter that would be only slightly better than F2A, and go for the new P&W engine to power their new fighter. Six HMGs, 200-220 gals, 250-280 sq ft wing." - quotes from my previous posts should point to the intended costumers)fighters.
> The combat-ready F8F-1 weighted 9500 lbs, give or take. The lighter engine, prop and no ADI saves us 100+100+100 lbs? Better punch means 400 lbs more, 30 gals of fuel means 200 lbs more (180 lbs of fuel, 20 for greater tank). 100 lbs for tad a bigger wing? That would be some 9900 lbs for the USN fighter; call it 10000 lbs.
> Army fighter does not need wing folding (saves 300 lbs?), neither the hook and any fuselage reinforcements that are needed for the every day CV landings (another 100 lbs). Undercarriage is also lighter (100 lbs) because of the same reason. So we're back at 9500 lbs here.
> 
> ...


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## tomo pauk (Oct 6, 2013)

Shortround6 said:


> we are back to the timing thing. If design work starts in 1938-39-early 40 _is_ Navy buying shore based aircraft? And even if they are can they afford both shore based and carrier based aircraft at the same time?
> _AND_ if you SKIP the F4F what do you use on the carriers?
> We also have an armament problem. The F4F was designed, at some point in it's early History to carry TWO.30 cal guns in the cowl and Two .50 cal guns in the wings. It was also designed without self sealing tanks and no armor.
> F4U was designed with One .30 cal gun in the cowl and one .50 cal gun in the cowl and one in each wing, no protection.
> The .50 gun was also firing at 600rpm at his point in time, changed to 800rpm was at some point in 1940 so _desired_ armament has to be taken into account. Armament was radically changed on later versions.



The F4F is/was a good example that a plane does not need an engine that has the shiny 'two stage engine' label on itself, but both the airframe and engine need to really put something so the complete fighter can perform. The two stage R-1830 offered less power at altitude than a single stage Merlin XX or 45, or DB-601N, with substantial drag penalty, and without any benefit in installed engine weight vs. those V-12s. Stick the big wings on the 1000-1200 HP radial and you have a mighty slow fighter. Big and draggy airplane needs more fuel - the weight spiral climbs.
Navy will not buy shore based aircraft, Grumman will make their CV capable ones. The new fighter will roll out from the factory from Jan 1941 on, F2As will be used in the mean time.



> F4U is _offering_ close to 400mph, not 370-380, _with_ carrier compatibility, _and_ better high altitude performance than a single stage plane would.
> There was only one prototype F4U and the design was extensively modified for the production version. TWO other factories were brought into the production scheme _before_ the first actual production plane (2nd F4U built) flew.
> The Carrier compatibility proved somewhat elusive but the Navy buying fighters it _KNEW it could not use on carriers_ in 1940?
> 
> Design work on the F6F was actually done in fits and starts and redo's from 1938 with the idea of using the Wright R-2600. It firmed up pretty well in the fall of 1940 (already getting late) with the mock up inspected in Jan 1941, changes were made to the length, wingspan and wing area, all were made larger. Of the two prototypes _ordered_ in the summer of 1941, One was to have a two stage supercharged R-2600 offering 1380hp at 21,500ft. and the 2nd was to use a turbo-charger. Navy appears to be interest in altitude performance.



Thanks for the F6F overwiev. 
F4U indeed makes 400 mph (and I have no quarrels to leave it as it was, in this thread), the USN accepts 390 mph F6F, in 1942 (to be produced in 1943) anyway. Compared wit this, a 370 mph fighter for 1941 is a far better asset - the speed of the R-2600 Hellcat prototype?




> True but they are close, or perhaps close enough to hold the line while the F4U with it's 390-400mph speed is brought into production.



370-380 mph should halved the speed difference LW fighters were enjoying.



> But you said you didn't want carrier compatibility? Which is it?
> 
> And carrier compatibility is NOT just a folding wing and a tail hook. It is meeting the take-off, stall and landing requirements, at least until enough shooting has occurred to convince people that a few more landing/take-off accidents are preferable to getting shot out of the sky. But that is way too late to make over a design.



Covered in previous post(s), Navy fighter would be somewhat of bigger wing, along with CV gear. 



> On the Army side you are facing the whole P-43, P-44, P-47 saga, Army ordered 733 P-47s off the drawing board in Sept 1940. Shoving a 1600-1650lb Twin Hornet into the P-43 instead of the 1450-1500lb R-1830 may not have been that big a deal for the P-44, trying to shove a 2300lb R-2800 into it is a whole new story even if you leave out the turbo.




Someone else should it do, then. Eg. Grumman was trying trying hard with Skyrocket; a R-2800 fighter instead might got them interested. Especially if it trashes P-40 on some comparison mock combat.



> Cutting wing area by 9% or so isn't going to do much on the high end. It was figured that 25% reduction in wing area was only good for a 3% increase in speed. Important in winning a race or gaining/holding a contract with performance penalties but not so important in the real world.



I've stated several times that wing profile would be closer to Wildcat's 15%, rather to the Corsair 18% (root thicknes both values), that would give significant drag reduction, too.



> The high lift devices are not free, they cost weight, fabrication time (money), and often drag.
> 
> Things got better as time went on but the early Fowler flaps had protruding tracks/supports, also notices the fixed slots on the model. The combination _was_ better than using a bigger wing. BTW the landing speed of the Lockheed 14 airliners was given as 65 mph, 8-10mph less than an F4F Wildcat. Cutting the wing area 25% increase stalling speed about 15% as a general rule of thumb, so the Lockheeds high lift devices were worth around 130-140 sq ft of wing. A worthwhile change on the airliner? On a single engine fighter?????


 
Thanks for the pictures.
The tracks/supports could be a pair at each side for the fighter's smaller wing, with inner track blended with fuselage. If the Hellcat's wing can then be not 334 sq ft, but 250 sq ft (75% of 334), it can be faster than Corsair. As fast as F8F-1?
The Corsair's wing was also a tricky thing to produce, costing weight, money time to produce, due to curved spars multi-part flaps. 



> True but KNOWING you are going to have production problems 1-2 years before they happen might mean you could solve them







> The F4F showed the way with two stage superchargers. The whole plane had a number of "problems" in service, which if the designers/users had known in 1939/40 what they knew in 1942/43 might have been changed. Like a number of other early fighters gained an awful lot of weight ( from prototype F4F-3, not XF4F-3) to F4F-4 it gained close 1200lbs (6260lbs to 7406lbs) with NO increase in power. It didn't affect speed that much but played h**l with the climb and altitude performance much like the P-40s.



+1 on this, the two stage R-1830 showing the P&W that 2-stagers are a good thing.



> The Spitfire is also a rather extreme example. Try comparing to a Hurricane II with the Merlin XX and remember that the F4F is getting little benefit from exhaust thrust (worth around 100hp at 25,000ft to the Hurricane).



Not so extreme. Previous, the Mk.I, was also capable for such feats, Bf-109E was there, too - both pre-ww2.
Hurricane was making 312-330 mph at 25000 ft, depending whether it carries cannons or MGs (plus variations between the particular aircraft).



> They are part of the reason the F8F did what it did. It was the beneficiary of 3-4 years worth of knowledge that did not exist in 1939.
> The Problem we are having is how much do you _unwind the clock_ to try to figure what was was possible or likely in a 1941 production plane vs a 1945 production plane.



Covered before - F4U is a base for performance comparison.



> Bostons had such short range that they were almost useless for bombing France or the low countries from bases in England. One reason they were adapted as night fighters, Bomber command couldn't figure out what to do with them
> Maybe the Russians can use them. While the R-2800 fighter would be a better/fighter bomber than the planes you mention that role WOULD NOT be on the minds of the people designing/ordering fighters in 1939/40. This is reward projection. You KNOW what roles fighters were put to use at in the mid and late war years. While the P-47 has quite a reputation as a ground pounder the B model carried NO external stores and the C and early D models carried ONE 500lb bomb on the fuel tank mount. The D-15 models and later had a reinforced wing to take external under wing loads and this was apparently a simple modifications as some older aircraft where modified in the field. BUT it means few, if any, people were contemplating using the P-47 as a "bomber" in 1940-41.
> I am not sure the VVS got ANY R-2800s aside from the ones in P-47s, I don't think they got any B-26s?



+1 on that, too.



> this may be true but it changes very little about the situation in 1939/40. A fighter using a single stage two speed supercharger R-2800 that will not go into production until mid 1941 at best will be viewed as an interim fighter to be used to "hold the line" until the desired fighters (P-38s, P-47s, F4Us and what ever odd balls the the procurement officers were favoring , like XP-55 Ascenders) can be built. Investing millions of dollars in a interim fighter when they already have the P-39, P-40 and F4F as interim fighters may be seen as a waste of resources even if the simple R-2800 fighter does over a margin of improvement over the older fighters.



The 'simple fighter' can be re-engined with 2-stage R-2800, or 2-stage V-1710. It can be a next-best-thing, in case the great performers encounter difficulties (they all did, one or other kind). It will be easier to get them exported, both from price and availability standpoint. AAF might have less objections to allow the export of it, rather than the great performers. 



> <snip>



Covered above.


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## tomo pauk (Oct 9, 2013)

Hello, again 


Shortround6 said:


> The F4F gained about 200lbs with it's folding wing and about 50lbs increase in weight due to "surface controls" but used a more complicated wing fold than the F8F.



Some of the weight increase was due to support needed for additional HMGs and drop tanks, changes from F4F-3 to F-4?



> View attachment 244691
> 
> Now I think the F8F used a power wing fold instead of manual but.......



Attachment not working.



> F4U was supposed to make much better use of ram at low altitude than the F6F. There were ducts and doors that lead from the wing inlets directly to the engine supercharger bypassing the auxiliary supercharger. Ram effect may change when the ducts/doors are configured for altitude. Please remember that the engine in early Bearcats was NOT identical to the ones used on the A and B engines even if it was single stage.



I was comparing the full throttle heights of the static engine (= no ram), and where the speed peaks (= max ram). Looks like the F4U-1 was gaining some 2000 ft, static vs. 'flying' engine. Eg. in low gear, it's 16500 ft vs. 18500; in high gear, it's 21000 ft vs 23000 ft. All for military power.
British aircraft data sheet gives, for Marauder Mk. III, the FTH in second gear as 13500 ft; the max speed (305 mph) in second gear was at 15000 ft - the gain in FTH was, via ram effect, 1500 ft. For a fighter making 370 mph - 2000 ft should be a good estimate.
Bearcat was able to 'earn' 4000 ft via the ram effect (16000 ft vs. 20600 ft, no ram vs. with maximum ram, military power full throttle heights); again, I'm not using Bearcat values if I can find something of earlier date to compare data. 



> The Problem is above 15,000ft. Many people on the Forum have been trying to work out better fighters for use at 20,000ft and above for the Americans in 1942. Better fighters at 5-15,000ft aren't really needed. At 21,500ft the single stage A engine has 75% of the power of the two stage engine in the Corsair. At 15,500ft the single stage "B" engine has about 78% of the power of the two stage engine. Neither includes RAM. That calls for a _lot_ of drag reduction.



For an early US fighter for above 20000 ft duties, it's either Packard Merlin (1st 300 engines delivered prior March 1942), or turbo V-1710, neither the choice for the USN if they can help it. Americans can build a 2-stage R-2800 fighter in 1942, it will enter combat in 1943 (1st 100 engines delivered prior June 1942). Goes without saying that a fighter with a two-stager will not be in position to save Lexingtion, Yorktown or Hornet - too late for that.

I've proposed two, almost sibling, aircraft that would be 10-15% lighter than Corsair, and of 10-15% less wing area. The wing would be also thinner. Despite that, I've never claimed that 'my' fighter would do 400 mph, at least not in the time of interest (1941-42). In normal power , F4U-1 does 370 mph when at 15500 ft (380 mph for Military power - 2.9% increase in speed for 11% increase in power). So even if we have the Corsair with 1-stager, it will still do 370 mph at 15500 ft. How much will do the plane with reduced weight and drag? 



> TO help put things in perspective you have a 9500hp airplane with around 1200-1250hp at 20,000ft. In the late spring/summer of 1942 Zeros start showing up with the Sakae 21 engine which offers 980hp at 19,685ft in a plane with a weight of 5600-5700lbs. A power to weight ratio about 3/4 that of you proposed fighter. You may have speed, you do not have climb or maneuverability. And I am not really talking about out turning a Zero, I am talking about doing a hard turn and retaining speed or regaining altitude after a firing pass or any other large maneuver that requires power to hold, regain altitude.
> Also for perspective you have the F4F with 1000 hp at 19,000 no ram (and depending on source 1000hp to 20-21,000ft with ram) with a 7-8,000lb plane.



'My' fighter (B series engine) has 0.126 HP/lb, Zero (with Sakae 21) has 0.173, F4F-4 has 0.125, F4F-3 has 0.143 (both F4s with ram).
F4U-1 has 0.137 HP/lb, Hellcat is in the ballpark; all values for 20000 ft. Looks like Zero is in a league of it's own (as it really was, such a light fighter), of the US fighters only the F4F-3 is somewhat ahead in thi category, but it's all but gone from the carriers by Spring/Summer of 1942. 
At 15000 ft, 'my' fighter has 0.158 HP/lb, Zero is at 0.195 (1100 HP?), F4F-4 is at (1100 HP) 0.138, F4F-3 is at 0.157.
F4U-1 has 0.150, Hellcat is there about.
Despite having far less power per weight, both Corsair and Hellcat were considered as far better fighters than Zero. Zero's RoC notwithstanding.




> True but figure your fuel needs, not what sounds good. 5 minutes at military, 15 minutes at max continuous (65-70 gals total?). 15-25 gallons for warm up and take off before switching to drop tanks. Max cruise ( 2100rpm and 33in is about 1 1/2 gallons a minute) and low speed cruise is going to be 40-60 gals an hour. 20 gal reserve? You have about 100-105 gallons to get home if you punch off the drop tanks at start of the fight. Even with the P-47 sucking down more fuel for Military power and max continuous it started with 80-95 gallons more. You may need a 75 gallon or better drop tank just equal the P-47s radius.



Two 75 gal drop tanks should do, for the starters. 



> While the CDo is not the whole story the P-47B is _supposed_ to have a flat plate equivalent between the F2A and the F4F and about 75% of that of the F4U-1D.
> A P-40E could burn 33-42gph in slow cruise depending on altitude.



Agreed.




> Telling the Navy they need to train their pilots another 20 hours to use your airplane is going to see your submission shuffled to the bottom of the pile _real_ quick. The Navy told the manufactures WHAT THE NAVY WANTED.
> Manufacturers did not tell the Navy how to train their pilots.



You are right, Navy calls the shots. There are few possible ways to get the fighter in the business anyway:
- the fighter is far heavier armed than initial XF4F and XF4U anyway - delete 2 HMGs until we do something with wings (earns also 5+ mph?)
- then, install the slats, and/or better flaps (slotted, Fowler)



> Initial specification that lead to the Grumman Avenger, issued in March of 1939, called for a stalling speed of 70mph _while carrying a torpedo_. There were 13 initial submissions from six manufacturers. The Navy reviewed them and cut it down to one each from Grumman, Vought and Brewster. in early fall of 1939. By Nov 3rd Brewster was out and the Navy was preparing to order 2 Grummans and one Vought.
> I can just imagine a manufacturing telling the Navy that they need to raise their stalling speed requirement by about 20% on the prototype aircraft. (and everybody knows the production aircraft will stall slightly faster than the prototypes)



Well put.


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## tomo pauk (Oct 26, 2013)

I'd like to return to this tidbit:



> While the CDo is not the whole story the P-47B is supposed to have a flat plate equivalent between the F2A and the F4F and about 75% of that of the F4U-1D.



The pg. 113 at the AHT lists indeed the flat plate equivalent as being between F2A and F4F - 6.39 sq ft (P-47) vs. 6.27 and 6.58 (USN fighters). However, to arrive at that flat plate for the P-47, the author multiplies the wing area of 300 sq ft with Cd0 of 0.0213. In other words, the P-47 was to have the Cd0 value better than Spitfire V, or Fw-190D-9, while surpasing the Fw-190A by a wide margin. The reference for that Cd0 is dated 11/41 - Nov 1941? 
Now, the pg. 598 of the AHT lists the P-47D's Cd0=0.0251 - on par with F4F, for example, or a tad worse than Fw-190A, ie. far more believable value. Multiplied with wing area, we arrive at value of 7.53 sq ft, or about 90% of the F4U-1D.


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## tomo pauk (Apr 11, 2014)

The ever elusive XF6F-4, ie. the Hellcat with single stage R-2800:

http://www.alternatewars.com/SAC/XF6F-4_(Land)_PD_-_November_1_1942.pdf

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## Shortround6 (Apr 11, 2014)

Thank you Tomo. 

While better performing than a Wildcat and doing pretty well at low level performance, as expected, falls off considerably at altitude. 

For anybody considering the R-2600 please look at the figures using "normal" power. 

Please note the reduced fuel and 1/2 ammo load in the first two columns. Switching to four .50s and 400 rpg ( 4 gun Wildcat layout, almost  saves about 30-40lbs.


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## tomo pauk (Apr 11, 2014)

Huge Hellcat's airframe plays havoc with performance, that's for sure. For either R-2600 or single stage R-2800, a substantially smaller lighter fighter design is needed - indeed sized like Bearcat or thereabout.


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## Shortround6 (Apr 11, 2014)

And a smaller and lighter fighter is not easily up-graded to the two-stage engine. 

It also took P&W four years to go from the 1850hp T-O engine (1500hp/14,000) to the 2100hp/T-O (1600hp/16,000ft) engine in the Bearcat prototype (without water injection) let alone the 2100hp/T-O (1700hp/16,000ft) engine used on the bulk of the -1 Bearcats (which also had water injection=2400hp?) and a few more years for the 2250hp/T-O (1600/22000ft) engine used in the -2 Bearcats. The Bearcats were getting close to or equaling earlier two stage power levels with as single stage engine _AND_ didn't need as much cooling air going through the cowl so they had less drag. A 1941-42 Bearcat is going to be a bit different than a 1944-5 Bearcat unless you bring back the later propeller knowledge.


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## tomo pauk (Apr 11, 2014)

It is not like I'm proposing starting from La-5 sized A/C  
The best that we can hope from a fighter with 250-270 sq ft wing (not too thick, 15% at root*), B series R-2800 and 'proper' exhausts is maybe 390 mph. That's winter of 1942/43 at earliest?
BTW, for the space demand of two-stage R-2800, I've posted a bit here.

*F6F = 334 sq ft, 15% at root; F4U = 314 sq ft, 18% at root


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## Shortround6 (Apr 11, 2014)

Winter of 1942/43 is when the F6F and F4U start showing up in training squadrons. P-47s were showing up in training squadrons in the summer/fall of 1942. 

Short time line for P-47

June 1942 sees 56th fighter group get first P-47Bs.
Sept 1942 sees last P-47B built. 
Oct 1942 sees P-47Cs in Production
Nov sees 56th fighter group declared operational _in the US._
Dec Sees first P-47s arriving in England as deck cargo. 
Feb 1943 sees the 602nd P-47C roll out of Farmingdale. 
.............Sees first P-47D-1.
March sees first operational use of the P-47 and it is not pretty.
It is not until the 2nd and 3rd week of April that operations really start. 

You want R-2800 powered fighters _in combat_ in Nov/Dec of 1942 you had better start rolling them out the factory doors, in numbers (at least a few dozen a month) and bug free in April or May of 1942.

Even the P-40F took a while. First flown June 30 1941 (before delivery of _production_ P-40*D*s), starts delivery Jan 3, 1942. July 1 1942 sees a batch loaded onto the aircraft carrier Ranger which sails for North Africa. Planes are flown off to Accra and from their flown across Africa to the Middle East By July 31/Aug1st they are starting to see action _14_ months after the prototype flew and it is pretty much a simple re-engine job of a plane already in production and service. 

When does your prototype have to fly? when does it have to start design? 

Granted with _enough_ use of the "retrospectroscope" you can get it into use in the winter of 1942/43 but at what cost? delayed F6F or P-47? Fewer B-26 bombers in 1942? The Venturas may not have seen much combat use but hundreds were used as trainers ( rather high power but there you are) and lead to the PV-1 Ventura patrol bombers and Harpoons which did good service in anti-sub work and in the Pacific. 

BTW a LA-5 carried 30% of weight of guns and ammo that a F6F did if the F6F was carrying full ammo. 

Perhaps a better use of the "retrospectroscope" would be to modify the US armament situation rather than  about with engines  

A P-40E carried only about 25-40lbs _less_ guns and ammo than a Hawker Typhoon with four 20mm cannon.


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## tomo pauk (Apr 11, 2014)

Shortround6 said:


> Winter of 1942/43 is when the F6F and F4U start showing up in training squadrons. P-47s were showing up in training squadrons in the summer/fall of 1942.
> ....
> You want R-2800 powered fighters _in combat_ in Nov/Dec of 1942 you had better start rolling them out the factory doors, in numbers (at least a few dozen a month) and bug free in April or May of 1942.
> ....
> When does your prototype have to fly? when does it have to start design?



The fighter with features I've listed would be the 3rd version. 1st version would be with A series engines (produced from early 1941 on) and 2nd version, with B series, would be produced from early 1942 on. The better exhausts should be incorporated in 3rd version, to be built from winter of 1942/43. So instead of training squadrons of winter of 1942/43, they will be deployed in service squadrons prior Pearl. Admittedly, not capable for 390 mph, but not much more slower.
A separate version can incorporate 2-stage engine.



> Granted with _enough_ use of the "retrospectroscope" you can get it into use in the winter of 1942/43 but at what cost? delayed F6F or P-47? Fewer B-26 bombers in 1942? The Venturas may not have seen much combat use but hundreds were used as trainers ( rather high power but there you are) and lead to the PV-1 Ventura patrol bombers and Harpoons which did good service in anti-sub work and in the Pacific.



'My' fighter can be produced in lieu of F6F. 
In 1942, the USA Allies need much more the capable fighters, rather than a trainer powered by two R-2800s. The role of marine patrol A/C can be assumed by more Hudsons and Liberators/Privateers.



> BTW a LA-5 carried 30% of weight of guns and ammo that a F6F did if the F6F was carrying full ammo.
> Perhaps a better use of the "retrospectroscope" would be to modify the US armament situation rather than  about with engines
> A P-40E carried only about 25-40lbs _less_ guns and ammo than a Hawker Typhoon with four 20mm cannon.



Yep, a more efficient armament might earn some extra RoC and tad of speed.


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## RCAFson (Apr 11, 2014)

tomo pauk said:


> The ever elusive XF6F-4, ie. the Hellcat with single stage R-2800:
> 
> http://www.alternatewars.com/SAC/XF6F-4_(Land)_PD_-_November_1_1942.pdf



Basically, until the R2800-10 is approved for higher boost in late 1944, there's really not going to be much difference in performance between the F6F-3 with the R2800-10 and the same aircraft with the single stage -27 engine, under about 15000ft or so where most naval air combat occurred. I wonder how much delay was imposed on the F6F program due to the use of the two stage engine? The XF6F-4 would have been a killer naval fighter in mid 1942.

OTOH, a P-47 with the R2800-27 would be pretty lacklustre even in Mid 1942.


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## tomo pauk (Apr 11, 2014)

The F6F program was one of the most expedient, not just for the USA of ww2, but world wide. 1st contract was signed in June 1941 for 'improved F4F'. The engine-related mistake might have been that XF6F-1 featured 1st the 2-stage R-2600 engine (talk about rare engines...), and not the 2-stage R-2800 from start. Once the realities of the war settled in, the contract was changed in May 1942, the R-2800s were specified. Note that this happened before the Akutan Zero was found, let alone repaired and tested. 1st production Hellcat was delivered in Oct 1942.

The P-47 without turbo does not make any sense - delete turbo and you go nose-first every time you apply power?


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## Shortround6 (Apr 11, 2014)

You may want to check the climb figures again. The XF6F-4 holds up pretty well compared to an F6F-3 up to around 10,000ft, after that not so good. like around 1 1/2 minutes longer to 20,000ft and that is with the F6F grossing over 1300lbs more and no, the 1300lbs are all not in the two stage supercharger. 

That 182 gallons of internal fuel the _good_ performance figures are done with can disappear pretty quick. An R-2800 can suck down over 4.5 gallons minute at Military power and 3.37 gallons a minute at max continuous. 5 minutes Military power and 15 minutes max continuous can suck up over 1/3 of the fuel. Operational radius without drop tanks is less than the F4F. 

The _good_ performance figures are done with less ammo per gun than the F4F-4 and the Navy was none too happy with how long the guns would fire in those planes. Went back to four guns with more ammo. Granted the Bearcat started with four guns but they may have been hoping for faster firing guns. there had been numerous projects for a number of years which finally bore fruit in late 1944/early 1945 and the M3 gun was standardized in April 1945. four 1200 rpm guns aren't quite the same as 4 750-800 rpm guns. Building an R-2800 powered fighter and only using four .50 cal guns to keep the weight down seems a little strange in 1942. 

I don't really believe the F6F was delayed much because of the engines, I have never heard of stories about early F6F airframes sitting at the factory waiting for engines. P&W was building over 200 engines a month When F6F production was under 10 a month. In fact P&W had built 117 two stage engines in 1942 by the end of June. Vought rolled out the first two Production F4Us in July and only 9 more in August. P&W built 124 two stage R-2800 engines in August. It sure doesn't look like the engine or engine development was the problem.


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## RCAFson (Apr 11, 2014)

Shortround6 said:


> You may want to check the climb figures again. The XF6F-4 holds up pretty well compared to an F6F-3 up to around 10,000ft, after that not so good. like around 1 1/2 minutes longer to 20,000ft and that is with the F6F grossing over 1300lbs more and no, the 1300lbs are all not in the two stage supercharger.
> 
> That 182 gallons of internal fuel the _good_ performance figures are done with can disappear pretty quick. An R-2800 can suck down over 4.5 gallons minute at Military power and 3.37 gallons a minute at max continuous. 5 minutes Military power and 15 minutes max continuous can suck up over 1/3 of the fuel. Operational radius without drop tanks is less than the F4F.
> 
> ...



Which F6F-3 stats are you using? The SAC data for the F6F-3 is from Oct 1945 when the R2800 was approved for higher boost, so it's not a fair comparison, and IIRC, they used more efficient props as well. The XF6F-4 stats for the heavy fighter include 250g fuel and 400rpg x 6. Using normal power the XF6F-4 It matches the F4F-4 in climb to 20k ft.

Xf6F-4/ F4F-4 (normal power with full internal fuel and 6 x .5in MG with ammo 2400/1440 rnds)

Time to climb 10k ft: 5.2 / 5.6 min
Time to climb 20k ft: 12.4 / 12.4 min

SL Vmax: 306 / 274 mph
5.7k ft VMax: 325 / 290
8.3k ft Vmax: 322 / 295
15k ft vmax: 344 / 310
20k ft vmax: 322 / 318

I would expect the -27 to have slightly better specific fuel consumption than the -10.


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## GregP (Apr 11, 2014)

Not sure what you guys are saying. Here is a test of the F6F-3: 

http://www.wwiiaircraftperformance.org/f6f/f6f-3-42874.pdf

that clearly shows a 375+ mph aircraft. The Hellcats we fly are all faster than the numbers above, but they don't DO that very often these days except in a dive from height. But they CAN.


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## Shortround6 (Apr 11, 2014)

Was using this;http://www.wwiiaircraftperformance.org/f6f/42633-climb.jpg

From Mike Williams site.
From September 1, 1944
Model F6F-3 Airplane - Periodic Performance Check 
TED No. PTR-2125
F6F-3 No. 42633

At low altitudes there will be little, if any difference in fuel consumption because at low altitudes the auxiliary supercharger is unpowered. 

As you go up in height it gets debatable or swaps back and forth. when the -27 shifts into high gear the supercharger takes 62% more power than it did in low gear. I have no idea how much power the auxiliary supercharger needs in low gear once it is engaged. 
A problem seems to be that the single stage engine was only allowed 47in manifold pressure in high gear instead of the 52.5-53in the two stage were pulling. Perhaps the inter-cooler? 

at any rate the single stage engine will use 4.5gallons an minute at low altitude in low gear at 52in MAP and 3.5-3.6 gpm at 12-14,000ft in high gear at 47 MAP and will use around or over 180 gallons an hour at 2400rpm and 42in MAP. Lower throttle settings of course use less. 
as a double check see that the XF6F-4 will use 182 gallons in 0.9 hours at 2400rpm in high gear.


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## gjs238 (Apr 11, 2014)

I would love to get the Army a R-2800 non-turbo powered fighter, prior to the F6F and F4U.
Something smaller and lighter built.
It seems like it would outperform the P-40 P-39.
Should also have great load carrying capacity for ground pounding.
Thinking fighter-bomber here.

On the other hand.........
It seems that a V-1710 powered P-51 could predate such a machine if North American Aviation were brought on board earlier.
That may be the better way to go.


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## RCAFson (Apr 12, 2014)

GregP said:


> Not sure what you guys are saying. Here is a test of the F6F-3:
> 
> http://www.wwiiaircraftperformance.org/f6f/f6f-3-42874.pdf
> 
> that clearly shows a 375+ mph aircraft. The Hellcats we fly are all faster than the numbers above, but they don't DO that very often these days except in a dive from height. But they CAN.



Lets plug in those numbers:


Xf6F-4/ F4F-4 / F6F-3 42784 (normal power with full internal fuel and 6 x .5in MG with ammo 2400/1440 rnds)

Time to climb 10k ft: 5.2 / 5.6 min / 4.3
Time to climb 20k ft: 12.4 / 12.4 min / 9

SL Vmax: 306 / 274 mph / 299
5.7k ft VMax: 325 / 290 / 316
8.3k ft Vmax: 322 / 295 / 323
15k ft vmax: 344 / 310 / 346 
20k ft vmax: 322 / 318 / 358

The time to climb numbers are a bit puzzling but under 15k the speeds are pretty close.


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## GregP (Apr 12, 2014)

They put the R-2800 to the best use they could with the programs they actually developed in the real world. The only R-2800 birds I'm not really fond of are the early P-47's. Later ones are pretty good. The F4U, F6F, F7F, F8F, A-26, and C-46 are all good uses of the engine, at about the time they were available give or take a bit, giving information from combat time to get to the factories and designers.

The performance of all the R-2800 birds was sufficient for what they were called upon to do, including the C-46.

About the time the Hellcat was first flying the R-2800 was available for use and they DID that.

What opportunity did we miss?


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## GregP (Apr 12, 2014)

What are your three numbers in your post RCAFson?

It may seem obvious to you, but not to me.

When I look at the report I posted, I get the following:

Military Power: 313 mph at S.L., up to 324 mph in the main stage at 3,300 ft or so, falling to 323 mph at 6,000 feet where the pilot engages low blower. That takes it almost linearly up to 369 mph at 18,100 ft and declines to 365 mph at 21,000 ft, where the pilot engages high blower and gets to 376 mph at 23,300 ft and decline a bit after that up to 29,100 ft, where he is making 360 mph. At 15,000 ft I get 356 mph.

I’m sure you can read the chart for normal power as well as I can, so I was wondering about your numbers. Maybe it is normal and mil from you site and one from mine? 

But I don't see any numbers from the link I posted. So I thought I'd ask. No agenda, just curious.


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## RCAFson (Apr 12, 2014)

GregP said:


> What are your three numbers in your post RCAFson?
> 
> It may seem obvious to you, but not to me.
> 
> ...



I used normal power in each case because those are the only figures that are given for each aircraft at full load. The XF6F-4 would also have an increase in performance at military and/or combat power but I don't have those numbers.


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## GregP (Apr 12, 2014)

I see. I think almost nobody fought at normal power. They might start that way, but as soon as they needed a bit extra, they'd use it.

Almost everyone I know quotes performance at the best power available, little realizing that very few minutes were ever spent there, and only when necessary (when panic set in or you seriously needed to separate from your opponent or catch or evade him).

So, the thing to do now would be to look at the performance of the Zero or other opponent at "normal" power. You can figure it at about the same percentage of power below maximum (about 1,130 HP for a Sakae 21) as the US engines. Radials aren't all THAT much different from one another unless the boost system is different.


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## tomo pauk (Apr 12, 2014)

GregP said:


> They put the R-2800 to the best use they could with the programs they actually developed in the real world. The only R-2800 birds I'm not really fond of are the early P-47's. Later ones are pretty good. The F4U, F6F, F7F, F8F, A-26, and C-46 are all good uses of the engine, at about the time they were available give or take a bit, giving information from combat time to get to the factories and designers.
> The performance of all the R-2800 birds was sufficient for what they were called upon to do, including the C-46.
> About the time the Hellcat was first flying the R-2800 was available for use and they DID that.
> 
> What opportunity did we miss?



We (=Allies) missed the opportunity to have a reasonable number of fighters with R-2800 in the nose as early as winter of 1941/42, not just in training units, but flying in combat. We have also missed the opportunity to replace the P-39s, P-40s and F4Fs (and other fighters the Allies were using) earlier than historically.

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## GregP (Apr 13, 2014)

The P-40 and F4F did pretty well considering we were inexperienced and STILL had a good kill-to-loss ratio. I'd ditch the P-39 as soon as the War Materiel Board removed the turbocharger. But that's hindsight.

I don't think we missed much. The early R-2800's weren't THAT great that they'd make a big difference. Once developed, it was a different story.

Again, just my take on it. And I'm not saying we could not have done a bit better, but there IS some development time required when a new engine with unproven reliability and durability is released before people trust it enough to stake a design on it.


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## tomo pauk (Apr 13, 2014)

I was under impression that Army decided to ditch the turbo? What should be the Soviets flying, in case you don't have P-39s - they rated it as good as Spitfires they flew, and far better than P-40s or Hurricanes. Maybe it would be better to give the Navy and Marine pilots a fighter that can best Zero in 1942?



> The early R-2800's weren't THAT great that they'd make a big difference.



We can take any year of war, and find out that the R-2800 is better than BMW-801 of that year. Or, better than Napier Sabre, at least when we talk about reliability, if not outright power. It took Japanese until 1945 to get something comparable with the R-2800 of 1942.



> And I'm not saying we could not have done a bit better, but there IS some development time required when a new engine with unproven reliability and durability is released before people trust it enough to stake a design on it.



The USAF have had enough trust to order the bomber with R-2800 from the drawing board in second half of 1939, that was produced from start of 1941.

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## GregP (Apr 13, 2014)

The USA wasn't IN the war in winter 1941 ... at least not until 7 Dec 1941. That's pretty much new year, 1942. There was NO possibility to tool up for a war footing before we declared war ... we were still coming out of the depression that started in 1929. Only a declaration of war could get us to think about a war footing.

So, we were doomed to START tooling uo for war around new year 1942, and there is ZERO possibility of doing so sooner.

Considering how long it takes to design, tool up and test, I think we did pretty well. Talking about making it happen sooner does not address the political realities of the time ... never gonna' happen.


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## gjs238 (Apr 13, 2014)

GregP said:


> The USA wasn't IN the war in winter 1941 ... at least not until 7 Dec 1941. That's pretty much new year, 1942. There was NO possibility to tool up for a war footing before we declared war ... we were still coming out of the depression that started in 1929. Only a declaration of war could bet us to think about a war footing.
> 
> So, we were doomed to START tooling upo for war around new year 1942, and there is ZERO possibility of doing so sooner.
> 
> Considering how long it takes to design, tool up and test, I think we did pretty well. Talking about making it happen sooner does not address the political realities of the time ... never gonna' happen.



The US was indeed tooling up for war prior to Dec 7.
There is thread after thread here about lend-lease, foreign sales, building CV's, developing CV air operations, developing long range heavy bombers, staging those bombers in attempts to exert military/political pressure, etc. All this was preparation and build-up.


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## GregP (Apr 13, 2014)

No were were NOT tooling up at anything NEAR a war footing. Foreign sales do not help the US Armed Forces prepare for war at all ... only when we buy the stuff for ourselves. Development rates were slow, almost glacial in speed, production of engines and aircraft was slow ... same for propellers. Maybe read America's Hundred Thousand by Francis Dean and look at the production numbers year by year. The numbers for 1940 / 1941 are nothing compared with real wartime production numbers. Now 1943 / 1944 was awesome. 1941 / 1942 was almost nothing by comparison.

1942 in the Pacific was a survival year until we could produce enough to get some to Europe and some to the Pacific to make a decent holding action until the war in Europe could be won, while raising and repairing what we could in Pearl Harbor. That's history, not speculation.


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## Jabberwocky (Apr 13, 2014)

GregP said:


> No were were NOT tooling up at anything NEAR a war footing. *Foreign sales do not help the US Armed Forces prepare for war at all *... only when we buy the stuff for ourselves. Development rates were slow, almost glacial in speed, *production of engines and aircraft was slow ... same for propellers*. Maybe read America's Hundred Thousand by Francis Dean and look at the production numbers year by year. The numbers for 1940 / 1941 are nothing compared with real wartime production numbers. Now 1943 / 1944 was awesome. 1914 / 1942 was almost nothing by comparison.



Ref the *bolded* bits, I'd have strongly to disagree. 

Foreign ordering in 1937-1940 was vital to increasing US production rates in the later war period, because the large orders required the early expansion of US aircraft manufacturing facilities and largely financed this expansion. To quote the USAAF's official history:

"By all odds* the most important single stimulus to the early expansion of the American aircraft industry was the demand for its products growing out of the desperate attempt by England and France *to offset the great superiority of the German Luftwaffe. Indeed, it *is perhaps not too much to say that the expansion financed by British and French funds in 1939 and 1940 advanced by as much as a year* the time within which American aircraft production would reach its peak." (The Army Air Forces in WWII, Vol. IV Men and Planes, Craven Cate, p. 300)

In the second half of 1940, foreign purchases of US aircraft were 1814 airframes, amounting to just over 50% of total US military production and nearly 75% of all combat types. 

While the US congress was dithering over aircraft purchases - it was still ordering aircraft in lots measures in dozens rather than hundreds even late into 1940 - the French and the British had been ordering aircraft in their hundreds and thousands. By September 1940, the French and British had ordered 14,000 aircraft and 25,000 engines, the British taking over the majority of French commitments following the fall of France. The money they spent paid for better than half of investment and the new plants and equipment in 1939-1941, that the later expansion of production was based on.


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## GregP (Apr 13, 2014)

Jabberwocky, 

The stimulus was for design. The production facilities were pitiful and were NOT improved until we went to war. Sure, new designs helped, but we didn't have anything like wartime training, wartime production, or wartime anything. 

All we did was develop a design corps with knowledge of how to set up production on a small scale. When war was declared, we figured out to scale it up for wartime production and NOT before. Yes the designs helped, but we were NOT in wartime production until sometime in 1943. Look at the production numbers, not wartime propaganda. Numbers didn't really ramp until 1943.

We made one P-38 in 1940; 207 in 1941; 1,479 in 1942; 2,497 in 1943; and 4,184 in 1944. 1945 saw 1,66 as we ramped down from P-38 production.

The P-51 was zero in 1940; 138 in 1941; 634 in 1942 (not exactly a production record, huh?); 1,710 in 1943 (still slow); and 6,982 in 1944. We made 6,103 in 1945 in half a year ... and then stopped.

The F6F was zero in 1940 and 1941 and we really ramped up to a whole 10 in 1942. 2.547 in 1943; 6,140 in 1944; and 3.578 in half of 1945.

So when exactly DID we ramp up? Basically late 1943 to early 1944. The fight was a holding action until then for the USA, not for the rest of the Allies.

You can find the numbers as easily as I can. Naval production looked the same.

Not sure about Army ground vehicles and don't care. This is an aviation forum, not a tank forum. I love to work on tanks and ride / drive them, but they aren't my cup of wartime history tea.

The Europeans, on the other hand, WERE ramping up since Hitler was making his ambitions known. If the UK had not started ramping up, they'd have been speaking German in short order. I am grateful they had foresight and ACTED while we slept.


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## Jabberwocky (Apr 14, 2014)

GregP said:


> Jabberwocky,
> 
> The stimulus was for design. The production facilities were pitiful and were NOT improved until we went to war. Sure, new designs helped, but we didn't have anything like wartime training, wartime production, or wartime anything.



Again, from the AAF official history:

"THE success of the American aircraft production program during World War II was to a large extent the result of bold prewar action and a consequent expansion of industrial capacity in 1940 and 1941."

That "bold prewar action" - more 1/2 of that was funded by foreign purchases of US aircraft. In 1939, half of the aircraft produced in the US were civilian designs. Of the military half, more than 60% went to the French and British. They were the ones who made it profitable for US manufacturers to expand their production facilities for military designs. By mid 1940, the French and British had ordered more than 10,000 military aircraft, or five times what the US had produced in the previous year.

The other half of the prewar action was the US deciding to ramp up military production in 1939/1940 with the various 'group' programs, but the initial $300 million funding decision didn't get the official go ahead until late 1939. By comparison, the Anglo-French purchasing commissions had committed to more than $600 in aircraft purchases by this time. It wasn't until the second half of 1940 that US purchasing commitments outstripped the British.

British and French orders were responsible for more than tripling the airframe production capabilities of the US manufacturing industry and quadrupling the productive capacities of its engine manufacturing industries. In 1938-1940:
Lockheed more than doubled its manufacturing floor space;
Pratt Whitney quadrupled its capacity;
Hamilton Standard Propellers tripled its capacity;
Consolidated, Boeing, Douglas, Martin, Lockheed, and North American each planned expansions ranging from 700,000 to 2,000,000 sq ft.

In 1939, the total floorspace of US aircraft factories and engine/prop/parts manufacturers was 9,455,000 sq ft.
It hit 13,116,00 sq ft at the beginning of 1940 and nearly doubled again to 25,456,000 sq ft at the beginning of 1941. It more than trippled in 1942, to nearly 80 million sq ft before peaking in 1943 at 167 million sq ft.

Year on year production increase (in numbers of aircraft) and total US military aircraft production:
1939, n/a, 2,141
1940: 189%, 6,086 
1941: 222%, 19,433 
1942: 146%, 47,836 
1943: 80%, 85,898
1944: 12%, 96,318

The expansion of the US military aircraft industry took off because of the decisions of 1938-1940, not of 1941. Capital investment takes time to come to fruition. You don't just decide to build a factory and 'poof' aircraft come out at full production volume, particularly not with the industrial technologies available in the late 1930s early 1940s.

The investment in new plants, machinery and facilities was funded in part by Anglo-Franco purchases. These were built in 1940 and 1941, came on stream in 1941 and 1942 and created the ground work for the US aircraft industry production miracle of 1943 and 1944. 

To quote Harry Stimson's 1947 report to the US senate on WW2 aircraft/engine production"

"In summary, the total 1941 production of combat and large transport aircraft and engines expanded more than three-fold over the 1940 level. Nevertheless, total output in 1941 was only about one-tenth the output of the of the peak year, 1944. A breakdown of the total reveals that most of the aircraft models used in large quantities during the war and several new engine models were not produced in significant quantities until after Pearl Harbour.
*It would be a serious error to infer, however, that the years 1940 and 1941 were wasted. Even though there was little production of certain types during those years, the prepartations made were instrumental in getting under way the volume output of the war-winning years. *By late 1942, quantity production of more of the models of which later were instrumental in winning air supremacy had started. By 1943 virtually all the new wartime plants were in volume proudction, their output equalling, and in the case of engines far exceeding, that of the home plants. "



> Not sure about Army ground vehicles and don't care. This is an aviation forum, not a tank forum. I love to work on tanks and ride / drive them, but they aren't my cup of wartime history tea.



By the end of 1941, aircraft accounted for more than 55% by value of all UK purchases (armaments, maunfactured/raw materials, ect) from the US. Aviation was their clear priority in US purchases.


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## GregP (Apr 14, 2014)

Yeah, 1941 / 1942 and maybe 1943 were ramp up years. I already SAID that. You can't produce anything when you are building the factory and tooling. You have to produce when the factories are completed.

What is your point? 

The production numbers were good for late 1942 to mid-1943 onward, but not much before that.


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## wuzak (Apr 14, 2014)

GregP said:


> Yeah, 1941 / 1942 and maybe 1943 were ramp up years. I already SAID that. You can't produce anything when you are building the factory and tooling. You have to produce when the factories are completed.
> 
> What is your point?
> 
> The production numbers were good for late 1942 to mid-1943 onward, but not much before that.



The point was that the factories were built pre-war (in the US perspective) based largely on the orders for aircraft by other nations (primarily the UK and France) and also on the expansion of the USAAC, which was being undertaken in the expectation of the possibility that the US would enter the war.

IIRC, the VLR Bomber project (which spawned the B-29) was started in 1940, the aim of which, in part, was to be able to bomb Germany from the Continetal USA in case Britain fell.


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## wuzak (Apr 14, 2014)

GregP said:


> Jabberwocky,
> 
> The stimulus was for design. The production facilities were pitiful and were NOT improved until we went to war. Sure, new designs helped, but we didn't have anything like wartime training, wartime production, or wartime anything.
> 
> ...



Greg, the aircraft you chose to highlight your argument are interesting.

The F6F wasn't even conceived in 1940. The F4F was only just getting into production in mid 1940.

The P-38 was still in the prototype/pre-production stage in 1940. The British and French still ordered 667 of them. Which dwarfed th enumber the USAAF had ordered at that stage.

The P-51 also hadn't been conceived (at least officially) by the time the British Purchasing Commission came to see North American. The P-51 was a result of the BPC's desire for ever more P-40s.


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## tomo pauk (Apr 14, 2014)

A comparison between F8F and F6F. Please note that distance between prop shaft and pilot's headrest is about equal. The fuselage of the F8F is far shorter (circa 5 ft). It is also shallower, since the supercharger air intake and oil cooler's intake were located in wings, not under engine as in the F6F. Not depicted here, the wing was also far smaller and lighter. 
BTW, one wonders whether the (X)F6F-6 would've been a more useful fighter than F8F-1.

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## Jabberwocky (Apr 14, 2014)

GregP said:


> Yeah, 1941 / 1942 and maybe 1943 were ramp up years. I already SAID that. You can't produce anything when you are building the factory and tooling. You have to produce when the factories are completed.
> 
> What is your point?
> 
> The production numbers were good for late 1942 to mid-1943 onward, but not much before that.



My point? Correcting misinformation.

When you wrote:



> There was NO possibility to tool up for a war footing before we declared war ... we were still coming out of the depression that started in 1929. Only a declaration of war could get us to think about a war footing.
> 
> So, we were doomed to START tooling uo for war around new year 1942, and there is ZERO possibility of doing so sooner.



and 



> production facilities were pitiful and were NOT improved until we went to war.



Those are demonstrably false. 

1. The US aircraft industry was expanding production at a record rate from late 1938 through to 1941 - thanks in no small part to foreign orders which dwarfed those of the US military at the time. At the end of 1939, of the $680 million million of orders for the entire US aircraft industry (civilian and military), $400 million was for Anglo-French military types. 
2. The US armed forced began their expansion to "start tooling up for a war" in the second half of 1940, not in the beginning of 1942. Look at the various 'group' schemes and the proposals for a 10,000 aircraft USAAF that were approved in 1939 and funded in 1940. 
3. US production aircraft/engine capacity more than trippled between the beginning of 1939 and the end of 1940.

Again, from the official history:



> The British Royal Air Force and the French Air Force played a major part during 1938 and 1939 in increasing the actual and potential production of the American aircraft industry.
> 
> ...
> 
> From the long-range viewpoint, of greatest significance for the United States was the willingness of foreign countries to pay for the plant expansion which was considered necessary in order to meet their orders on time. It is accurate to say, then, that the initial expansion of the American aircraft industry in 1939-40, and one which was of great benefit to the country, was paid for by Great Britain and France.


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## GregP (Apr 14, 2014)

Don't think so at all Jabberwocky. 

The USA was firmly in a peacetime buildup until after Pearl Harbor. We had done some designs, but were procuring them at very small rates. You (maybe not YOU, but someone) have mentioned my choice of aircraft. OK, let's look at them. The percentages of total production are for 1940 through 1945:

P-38: 0.01%, 2.06%, 14.74%, 24.89%, 41.70%, 16.60%. Built 83.19% in 1943, 1944, 1945.
P-39: 0.14%, 9.70%, 20.24%, 51.82%, 18.11%, 0.00%, Built 69.93% in 1943, 1944, 1945.
P-40: 5.92%, 17.10%, 29.35%, 32.40%, 15.23%, 0.00%. Built 47.63% in 1943, 1944, 1945. The USAAF started the war with this one.
P-47: 0.00%, 0.01%, 3.39%, 28.23%, 45.05%, 23.32%. Built 96.60% in 1943, 1944, 1945.
P-51: 0.00%, 0.89%, 4.07%, 10.98%, 44.85%, 39.20%. Built 95.04% in 1943, 1944, 1945.
F4F: 1.34%, 4.10%, 18.60%, 19.45%, 39.60%, 16.92%. Built 75.96% in 1943, 1944, 1945.
F4U: 0.01%, 0.00%, 1.55%, 19.91%, 47.37%, 31.16%. Built 98.44% in 1943, 1944, 1945.
F6F: 0.00%, 0.00%, 0.08%, 20.75%, 50.02%, 29.15%. Built 99.92% in 1943, 1944, 1945.

The ONLY fighter with lass than half built in 1943 - 1945 was the P-40. 

That accounts for 95,639 fighter aircraft, 84.49% of which were built from 1943 - 1945.

I think I just proved my point that 1943 - 1945 were the wartime production years and the rest was ramp-up, unless you just want to argue for the sake of arguing. I don't wish to pursue that.


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## wuzak (Apr 14, 2014)

Production was in the late war years.

However, the investment in facilities for production was in the early war years - 1940/41/42.

Take the P-38, for example. As you say, only one was built in 1940. However, some 700 or so were on order. The bulk of these (667) were from British and French orders. It is these orders that gave Lockheed the confidence to obtain the facilities to build them.

The P-40 was another example. It was being built in decent numbers in 1940. But where did they go? Many went to Europe. And there were many more on order from Britain and France, and greater production was required. Hence the British Purchasing Commission turning up at North American looking for additional production facilities for the P-40.


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## GregP (Apr 14, 2014)

Yes, they started ramping up for wartime production about Dec 7 1941. Prior to that time they produced designs, prototypes, and low rate initial production units that were GOING to be acquired slowly ... until war nixed that option. 

The P-40 was an easy change since it was built before the war as the P-36. All they really did was change engines and propellers. The former P-36 production line was already in use and simply changed over to P-40's. They also only built about 5.44% of the F4F Wildcats in 1940 - 1941, so they apparently could NOT change over biplane production lines to the Wildcat with the same ease as with the P-40.


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## gjs238 (Apr 14, 2014)

*OMG*


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## wuzak (Apr 14, 2014)

Well, let's see.

The French ordered 100 Hawk 75As, 100 Hawk 75A-2s, 135 Hawk 75A-3s and 395 Hawk 75A-4s. 284 A-4s were built before France fell, though they weren't delivered.

Curtiss Hawk with Armee de l'Air

Considering the numbers of aircraft the USAAC were ordering at that time (1938/39), orders for 730 Hawk 75s would have been very welcome to Curtiss.

They also had plentiful orders for P-40s for the French and British in 1939/40. The USAAC even deferred supply of P-40s so that they could be delivered to Britain.


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## GregP (Apr 14, 2014)

I imagine such an order would be quite welcome for any aircraft maker of the time ... or even today.


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## Piper106 (Apr 15, 2014)

tomo pauk said:


> The ever elusive XF6F-4, ie. the Hellcat with single stage R-2800:
> 
> http://www.alternatewars.com/SAC/XF6F-4_(Land)_PD_-_November_1_1942.pdf



Does anyone have any daata on how center of gravity was maintained on the XF6F-4 version???
Not only was the XF6F-4 engine lighter than those used in the -3 and -5 versions, but the R-2800-27 single stage two speed engine had no need for the intercooler(s) used on the two stage engine Hellcats. That is a lot less weight in the nose of the XF6F-4. Was weight added to the nose, engine mounts exxtended, or aft fuselage equipment repositioned to maintain balance????


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## tomo pauk (Apr 15, 2014)

The weight difference for the bare engines was 180 lbs (mostly due to a smaller S/C), plus maybe another 150-200 lbs for the inter-coolers? OTOH, much of the that weight was 'subtracted' from the area of the fuselage rather close to the wing leading edge, so the effect to the CoG were not that pronounced?


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## Jabberwocky (Apr 15, 2014)

wuzak said:


> Well, let's see.
> 
> The French ordered 100 Hawk 75As, 100 Hawk 75A-2s, 135 Hawk 75A-3s and 395 Hawk 75A-4s. 284 A-4s were built before France fell, though they weren't delivered.
> 
> ...



The scale of French and British ordering in 1939/1940 was, for the time, simply staggering. In 1939, the Anglo-French Purchasing Commission initially ordered 2400 fighters and 2160 bombers and 13,000 engines. By the end of 1939, orders had swolen to more than 8200 aircraft and 20,000 engines, this was more than the USAAF and USN had ordered in the previous five years combined. By March 1940, the orders had reached 14,000 aircraft and more than 25,000 engines.

In addition, with the first orders came a $37 million capital investment kicker for expansion of manufacturing facilities and another $7 million to finance the design/research of new aircraft types. Inflation adjusted, that $44 million was over $750 miillion in 2014 dollars. By June 1940, the British and French had committed $72 million on capital expansion incentives for US manufacturers ($1.2 billion in 2014 dollars). By the beginning of 1941 the British and French had paid $123,840,000 in special additions for the capital expansion of US aircraft/engine manufacturing. That's a little more than $2.1 billion in current dollars. 

Given that between September 1939 and July 1940 $52 million ($877 million in 2014 dollars) had been actually spent by US companies on exapansion, I'd argue it is fair to say the 1939-1941 expansion of US aircraft manufacturing (more than tripling capacity) was paid for by the French and British.

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## GregP (Apr 15, 2014)

Can't argue with that conclusion, Jabberwockey, though the industry still needed a lot MORE expansion to handle the production numbers of 1944 and 1945.


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## Shortround6 (Apr 21, 2014)

When the US _started_ tooling up maybe subject to interpretation but may be indicated by President Roosevelt's speech of May 16 1940. (full text here : http://www.airforcemag.com/MagazineArchive/Documents/2009/June 2009/0609fullkeeper.pdf )

were he said (in part);

" During the past year American production capacity for war planes, including engines, 
has risen from approximately 6,000 planes a year to more than double that number, 
due in greater part to the placing of foreign orders here."

and " Our immediate problem is to superimpose on this production capacity a greatly 
increased additional production capacity. I should like to see this nation geared up to 
the ability to turn out at least 50,000 planes a year. Furthermore, I believe that this 
nation should plan at this time a program that would provide us with 50,000 military 
and naval planes."

Now it takes several years to build and equip a factory and hire and train a work force. The factories that _began_ to produce large numbers of engines and aircraft in 1942 were planned and started construction in 1940 ( those that were NOT already expanding or under construction from the foreign orders). However to reach the 1944 production numbers even more plants and/or larger plants were needed. For example the Ford plant building R-2800s had ground broken on construction in Sept of 1940 and started making engines (in more than a handful) in Nov 1941. Production reached just under 800 a month by the end of 1942 but even before then it was decided that that was not enough and an "expansion" was ordered that roughly doubles the floor space. a further "expansion" was ordered soon after that resulted in over _triple_ the original floor space and resulted in a peak production of over 2400 engines in one month in the middle of 1944. Now _when_ did Ford gear up to build R-2800s, before or after Pearl Harbor? 
In actual fact,,,, both. 
Buick, Chevrolet and Studebaker were all brought in to manufacture aircraft engines in the fall of 1940 a few months after Ford and Packard but results don't show up until after Pearl Harbor. Once again, building construction, machine tool production and installation and work force hiring and training. I have no details on when or if the Buick, Chevrolet and Studebaker plants were expanded after initial construction. 

Some idea of initial expansion of production my be taken from looking at some pre-war numbers for P&W and Wright. 
By late 1938 P&W had delivered about 13,500 engines from the companies start in 1925. That includes Wasps, Wasp Juniors, Hornets ( of two types), Twin Wasps, Twin wasp Juniors and a few twin Hornets. In 1939 P&W built 1792 Twin Wasps, in 1940 they built 3643 Twin Wasps and in 1941 for the first 11 months they built 5810 Twin Wasps and 1469 R-2800s (production of the smaller Wasp and Wasp Junior are not listed).
Wright had sold about 8,000 Cyclone engines up until Aug of 1938, starting before 1930, with 1300 sold in 1937 and about 1000 sold in the first 7 months of 1938. in 1939 they built 2056 Cyclones (R-1820s), in 1940 2272 (+ 1925 R-2600s) in 1941 they built 4552 Cyclones and 7186 R-2600 engines. Granted production went up even more after that and plants were added in Cincinnati (first engines delivered in the summer of 1941 so plant construction started when?) and Wood-Ridge but they numbers sure indicate that more was going on that adding 2nd or 3rd shifts of workers to existing plants.

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## GregP (Apr 21, 2014)

Nice find, Shortround.

I'd listen to any of Roosevelt's speeches but draw the line at Lyndon Johnson campaign speeches and any of Jimmy Carter's speeches. 

They rank right up there with any talking by Pee Wee Herman.


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## gjs238 (Apr 21, 2014)

GregP said:


> Nice find, Shortround.
> 
> I'd listen to any of Roosevelt's speeches but draw the line at Lyndon Johnson campaign speeches and any of Jimmy Carter's speeches.
> 
> They rank right up there with any talking by Pee Wee Herman.



How do you rank the Governator?


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## GregP (Apr 21, 2014)

At least he won't be able to say, "I'll be back!"

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## P-39 Expert (May 29, 2018)

GregP said:


> Not sure what you guys are saying. Here is a test of the F6F-3:
> 
> http://www.wwiiaircraftperformance.org/f6f/f6f-3-42874.pdf
> 
> that clearly shows a 375+ mph aircraft. The Hellcats we fly are all faster than the numbers above, but they don't DO that very often these days except in a dive from height. But they CAN.


Sorry, couldn't help myself. Had to post this. Enjoy.


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## tomo pauk (May 30, 2018)

P-39 Expert said:


> Sorry, couldn't help myself. Had to post this. Enjoy.



Nothing to enjoy there. We all know that stripped-down A/C can out-perform fully-outfitted A/C.
Plus, how exactly does it contribute to the thread?


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## P-39 Expert (May 31, 2018)

The Hellcat and P-39 were both mentioned in the thread, and the thread was old.

Why do you say it was stripped?


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## fubar57 (May 31, 2018)




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## Vincenzo (May 31, 2018)

"Airplane does not meet Air Corps cooling requirements at any of these powers"

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## tomo pauk (May 31, 2018)

P-39 Expert said:


> The Hellcat and P-39 were both mentioned in the thread, and the thread was old.
> Why do you say it was stripped?



Because it was with 87 gals of fuel, as it can be seen via the takeoff weight.
P-39N is too late for the time frame, since it was in production last 2 of 24 months of interest here. Same applies fot the Hellcat.


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## Shortround6 (May 31, 2018)

It may be even worse if you open the whole report.

"At 9700ft and at manifold pressures above 55" hg, mixture temperatures were within the detonation range." 

Actual coolant and outside air temperatures are listed in the full report 

"High Prestone temperature observed in climb was 136^ C at 11,000ft at 1235hp with a free air temperature of +4^C."

This is 11^C above the *max* temp listed in the engine chart for a P-39Q.

I will note (trying to be fair) that this air temperature was bit warm for Buffalo in October. Standard air temp charts call for 19.77^F (-6.8^C)at 11,000f on a standard 59^F (15^C)day. However a standard "Hot" chart with 100^F (37.8^C) at sea level calls for temp of just under 80^F (25^C)at 11,000ft. Other charts may vary. Hot charts did vary, the one I used is supposed to be "typical".


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## P-39 Expert (May 31, 2018)

Vincenzo said:


> "Airplane does not meet Air Corps cooling requirements at any of these powers"


Neither did the P-47B, P-51A, or SpitfireV for that matter.


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## P-39 Expert (May 31, 2018)

tomo pauk said:


> Because it was with 87 gals of fuel, as it can be seen via the takeoff weight.
> P-39N is too late for the time frame, since it was in production last 2 of 24 months of interest here. Same applies fot the Hellcat.


Again, I disagree on the weight.
Saving 33gal (120-87) would only account for 198#. The N grossed 7650 with 120gal fuel, an additional 198# would have increased weight of the test plane to only 7472# (7274+198), still below published gross weight.
Joe Baugher's site shows the first 100 N models to be within serial numbers 4944 to 5043 and this plane was #4400 (probably a K or L with the new -85 9.6 geared engine). The reduced fuel models started with the 167th example indicating the test model had the full 120 gallons. No K or L models had reduced fuel capacity.
ALL the AAF planes were tested (official performance test) at a weight below their published weights. If you discount this test then you should discount every other test. This indicated they were using average or mean fuel during the flight. Taking off at full gross weight for the test and "correcting" the test weight to reflect average or mean fuel for that flight.
The British "corrected" (their term) the gross weight in their tests to 95% of takeoff weight to reflect the average weight of that flight with average fuel. 
Also, in the performance tests the amount of fuel was almost never mentioned, even when they state the number and caliber of guns and the corresponding amount of ammunition.
When reduced fuel is mentioned, specifically one test each with the P-51A and P-38G, both those planes were lighter than published weights AFTER the reduced fuel is deducted. 
Again, if you discount this test than you should discount every other AAF test, they were all light.


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## Vincenzo (May 31, 2018)

P-39 Expert said:


> Neither did the P-47B, P-51A, or SpitfireV for that matter.



give me the sources


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## Vincenzo (May 31, 2018)

So the test is a P-39K-1-BE modified for became a N-1...


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## P-39 Expert (May 31, 2018)

Vincenzo said:


> give me the sources


wwiiaircraftperformance.org, same as for the P-39.


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## P-39 Expert (May 31, 2018)

Vincenzo said:


> So the test is a P-39K-1-BE modified for became a N-1...


My guess since I couldn't find 42-4400 in the list of serial numbers.


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