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

[Shortround6]

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.

 

[RCAFson]

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.

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.

 

[GregP]

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.

 

[Shortround6]

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.

 

[gjs238]

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.

 

[RCAFson]

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.

 

[GregP]

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?

 

[GregP]

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.

 

[RCAFson]

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.

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.

 

[GregP]

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.

 

[tomo pauk]

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.

 

[GregP]

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.

 

[tomo pauk]

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.

 

[GregP]

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.

 

[gjs238]

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.

 

[GregP]

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.

 

[Jabberwocky]

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.

 

[GregP]

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.

 

[Jabberwocky]

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.

 

[GregP]

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.