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

[tomo pauk]

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?

 

[Shortround6]

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.

 

[tomo pauk]

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 F4U, not F4F.

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

 

[Shortround6]

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.

 

[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.

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.

 

[Shortround6]

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.

 

[tomo pauk]

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.

 

[Shortround6]

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.

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.

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

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.

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.
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.
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.

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.

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.
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.

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.

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.
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)

 

[tomo pauk]

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.

 

[tomo pauk]

Hello, again

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.

 

[tomo pauk]

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.

 

[tomo pauk]

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

 

[Shortround6]

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.

 

[tomo pauk]

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.

 

[Shortround6]

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.

 

[tomo pauk]

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

 

[Shortround6]

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-40Ds), 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 dink about with engines

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

 

[tomo pauk]

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 dink 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.

 

[RCAFson]

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.

 

[tomo pauk]

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?