1941: the best case for 350+ mph CV fighters?

pinsog · May 19, 2019

Also Shortround, I knew they had turbocharger control problems early on, I have an idea on how this might have worked with perfect hindsight.

Grumman sees tests on AP-4/P43 in 1939. Hey guys they are getting 1200 hp at 25000 feet with that. Grumman builds an F4F-3 with a turbo in the same position as the P43. US Navy is unsure about it, not trusting it yet. Grumman plumbs the production F4F-3 with the holes in the proper place, fuel tank curved on the bottom, radios behind the seat mounted up higher, etc. Essentially the bolt holes are there but the equipment is not installed, and it is shipped with the original P&W 1830 2 stage engine. But, it is set up so that if the Navy sees fit to change over to the turbocharged engine, it is a simple matter of installing the turbo, ducting, controls etc in the bolt holes provided.

It didn't happen, but at least that might be a plausible plan.

Shortround6 · May 19, 2019

tomo pauk said:
With that said, I tend to favor a R-2800 powered fighter for the USN in this thread - offered a lot of power under 20000 ft.

Trouble is for production fighter in 1941, you are stuck with the R-2800-5 (or equivalent) that offers 1850hp from sea level to 2700ft (plenty of power) but is down to 1500hp at 14,000ft in high gear , which is still a lot of power but the engine weighs 2270lbs. and is 52in diameter (bare engine).

the figures for the power for the F4F-3 may be true but they don't tell the whole story. The F4F-3 (not the F4F-3A) would hold 1050hp to 11,000ft and would hold 1000hp to 19,000ft (no ram). the R-2800-5 may have down under 1400hp at 19,000ft.
The engine used in Corsair would give 1800hp at 15,500ft. without water injection. 20% more power over 10% higher up.

tomo pauk · May 19, 2019

Shortround6 said:
Trouble is for production fighter in 1941, you are stuck with the R-2800-5 (or equivalent) that offers 1850hp from sea level to 2700ft (plenty of power) but is down to 1500hp at 14,000ft in high gear , which is still a lot of power but the engine weighs 2270lbs. and is 52in diameter (bare engine).

the figures for the power for the F4F-3 may be true but they don't tell the whole story. The F4F-3 (not the F4F-3A) would hold 1050hp to 11,000ft and would hold 1000hp to 19,000ft (no ram). the R-2800-5 may have down under 1400hp at 19,000ft.
The engine used in Corsair would give 1800hp at 15,500ft. without water injection. 20% more power over 10% higher up.

I'm not stuck with R-2800-5, I'm (or, USN is) blessed with it.

Shortround6 · May 19, 2019

pinsog said:
Shortround, will a turbocharger heat the intake air more than a supercharger at low altitude? If an F4F-3 and a turbocharged F4F-3 are both running at 1100 hp, side by side at 1000 feet, could they use the same intercooler? Or does a turbocharger produce more heat for a given hp than a supercharger?

I don't think it makes much difference, Both the P & W aux stage and the GE turbocharger were somewhat less than ideal (lower efficiency) at this point. The whole idea of the turbo at this point in time was try to duplicate sea level conditions at higher altitudes so at low altitude the waste gate is wide open and the turbo is "idling" providing little or no boost.
Of course at low altitude the P & W auxiliary supercharger is not clutched in either so it is not providing any boost or creating any heat in the intake tract.

You don't get any additional power at low altitude.

It is not until either the Aux supercharger is clutched in or the turbo engine gets to around 3700-4000ft that the waste gate will begin to close and provide any boost to the engine that intercoolers have any role at all. On a turbo engine the army's goal for the intercooler was to keep the intake air from exceeding 100 degrees F at the inlet to the carburetor.

My reason for asking is, instead of installing a larger intercooler like you would need at 25,000 feet, just use the original intercooler and you would still gain 100 hp down low. Or maybe slightly increase the size of the intercooler to get 1,200 hp up to 20,000 feet instead of 25,000 feet.

The turbo doesn't take any power from the engine to drive so you gain there, the question is what point does the rise in intake temperature come into play.

Shortround6 · May 19, 2019

tomo pauk said:
I'm not stuck with R-2800-5, I'm (or, USN is) blessed with it.

What I mean is that is only engine in production in numbers in 1941. There is no other version.

It weighs 800lbs more than an R-1830 single stage 2 speed engine and about 700lbs more than the two stage engine.

Most of your extra power is going to be used up hauling around the extra weight and bigger airframe needed to hold the engine and the rest of the powerplant.

pinsog · May 19, 2019

Shortround6 said:
I don't think it makes much difference, Both the P & W aux stage and the GE turbocharger were somewhat less than ideal (lower efficiency) at this point. The whole idea of the turbo at this point in time was try to duplicate sea level conditions at higher altitudes so at low altitude the waste gate is wide open and the turbo is "idling" providing little or no boost.
Of course at low altitude the P & W auxiliary supercharger is not clutched in either so it is not providing any boost or creating any heat in the intake tract.

You don't get any additional power at low altitude.

It is not until either the Aux supercharger is clutched in or the turbo engine gets to around 3700-4000ft that the waste gate will begin to close and provide any boost to the engine that intercoolers have any role at all. On a turbo engine the army's goal for the intercooler was to keep the intake air from exceeding 100 degrees F at the inlet to the carburetor.

The turbo doesn't take any power from the engine to drive so you gain there, the question is what point does the rise in intake temperature come into play.

Makes sense so far. So if they installed a turbocharger, would they be able to get 1200 hp from 12000-19000 instead of 1000 because they aren't having to use engine power to turn high gear on the 2 stage supercharger and still use the same intercooler? (not sure how much power it took to spin high gear on a P&W 1830-76)

Might be close to break even weight on a turbocharged F4F-3 if they used the Wright 1820 instead of a P&W 1830.

tomo pauk · May 19, 2019

Shortround6 said:
What I mean is that is only engine in production in numbers in 1941. There is no other version.

It weighs 800lbs more than an R-1830 single stage 2 speed engine and about 700lbs more than the two stage engine.

Most of your extra power is going to be used up hauling around the extra weight and bigger airframe needed to hold the engine and the rest of the powerplant.

I don't need another version, this one will do. Yes, it is heavier than R-1830 of any favor, but nobody is expecting a free lunch here.

On the other hand, how about a derivative of the R-2180A? The 2-stage supercharged version was suggested by the P&W, so was the turboed.

Kevin J · May 19, 2019

tomo pauk said:
P&W delivered nine R-2800s from Jan-Nov 1940 (those can go in the prototypes), another eight in Dec 1940, another hundred before end of the March of 1941.

Were these single stage, two stage or both?

tomo pauk · May 19, 2019

Kevin J said:
Were these single stage, two stage or both?

Vast majority were of 1-stage supercharged type.

Shortround6 · May 19, 2019

Kevin J said:
Were these single stage, two stage or both?

Just about all were single stage.

for B-26 fans these are the engines that went into the early B-26s.

Shortround6 · May 19, 2019

tomo pauk said:
On the other hand, how about a derivative of the R-2180A? The 2-stage supercharged version was suggested by the P&W, so was the turboed.

P & W built about 30 of the R-2180 engines so the existence of actual production tooling for many parts is questionable.

It used the same bore and stoke as the R-2800 so piston and cylinder parts may be available but production of this engine is only going to cut into/delay the R-2800.

Development was shut down before the war started but the best it ever did seems to be 1400hp for take-off and most versions/proposals don't even mention military power.
It also has the same diameter as the R-2800 so it is no help in streamlining.

Shortround6 · May 19, 2019

pinsog said:
Makes sense so far. So if they installed a turbocharger, would they be able to get 1200 hp from 12000-19000 instead of 1000 because they aren't having to use engine power to turn high gear on the 2 stage supercharger and still use the same intercooler? (not sure how much power it took to spin high gear on a P&W 1830-76)

Might be close to break even weight on a turbocharged F4F-3 if they used the Wright 1820 instead of a P&W 1830.

The R-1830 is a bit hard to estimate because P & W only gave a few versions an actual military rating. They allowed 2700rpm for take off but those altitude ratings given in previous posts were at 2550rpm.

edit. The pilot's manual for the F4F-4 also does not list a military power.
It does give an emergency take-off power setting using 2900rpm but restricts it to one minute only and rescinds permission to use this rpm for emergency climb. It says this rpm should only be used with the prop set to a fixed pitch and that is OK for take-off.
I have no idea if this restricting the R-1830 in the wildcat was due to cooling problems with engine, or a propeller governor problem or what???
It doesn't matter if the engine is using the auxiliary supercharger or not or what the gear the aux supercharger is in.

Kevin J · May 19, 2019

With a first flight date of May 29th 1940, it seems to me that it would be very unlikely that the Corsair could have seen operational service any time in 1941. Maybe if the Hellcat rather than the Skyrocket had flown first in 1940 with a single stage R-2800 then maybe maybe 1941, but at Pearl Harbour there was only one carrier operating the Wildcat, so does the Wildcat get canned?

Shortround6 · May 19, 2019

Kevin J said:
but at Pearl Harbour there was only one carrier operating the Wildcat,

This may be technical true but it would seem to need at least a few qualifiers?

In Jan 1942 the Last US navy carrier Squadron landed it's F2A Buffaloes (gave them to the Marines) so either there was a truly massive and rapid requirement or something is out of whack.

Grumman had completed 402 Wildcats and Martlets by the end of Nov of 1941. 106 of those had been built in 1940. How many went to the Royal navy Bty Dec 7th I don't know.

At least one US carrier was being used as an aircraft ferry at the time of Pearl Harbor to bring planes to Midway and Wake so perhaps it's own squadrons were ashore on Hawaii on Dec 7th?

You also have this from wiki "When the Japanese attacked Pearl Harbor on 7 December 1941, Saratoga was entering San Diego Harbor to embark her air group, which had been training ashore while the ship was refitting. This consisted of 11 Grumman F4F-3 Wildcat fighters of VF-3 (under the command of Lieutenant Jimmy Thach), 43 Douglas SBD Dauntless dive bombers of VB-3 and VS-3, and 11 Douglas TBD Devastator torpedo bombers of VT-3. The ship also was under orders to load 14 Marine Corps Brewster F2A-3 Buffalo fighters of VMF-221 for delivery in Oahu. "
So the Saratoga was not anywhere near Pearl Harbor on Dec 7th and had no planes of any kind on board having just left the Bremerton navy yard after a nearly year long modernization and refit.
Of the 7 US Carriers only 3 (including the Saratoga) were in the Pacific, the other 4 were in the Atlantic. So all four of them could be said not to be at Pearl Harbor, doesn't mean they didn't have Wildcats on board.

I would note that Grumman was increasing production and built another 332 F4Fs in the first 4 months of 1942 and for the rest of the year production never dropped below 100 per month.

Kevin J · May 19, 2019

Shortround6 said:
This may be technical true but it would seem to need at least a few qualifiers?

In Jan 1942 the Last US navy carrier Squadron landed it's F2A Buffaloes (gave them to the Marines) so either there was a truly massive and rapid requirement or something is out of whack.

Grumman had completed 402 Wildcats and Martlets by the end of Nov of 1941. 106 of those had been built in 1940. How many went to the Royal navy Bty Dec 7th I don't know.

At least one US carrier was being used as an aircraft ferry at the time of Pearl Harbor to bring planes to Midway and Wake so perhaps it's own squadrons were ashore on Hawaii on Dec 7th?

You also have this from wiki "When the Japanese attacked Pearl Harbor on 7 December 1941, Saratoga was entering San Diego Harbor to embark her air group, which had been training ashore while the ship was refitting. This consisted of 11 Grumman F4F-3 Wildcat fighters of VF-3 (under the command of Lieutenant Jimmy Thach), 43 Douglas SBD Dauntless dive bombers of VB-3 and VS-3, and 11 Douglas TBD Devastator torpedo bombers of VT-3. The ship also was under orders to load 14 Marine Corps Brewster F2A-3 Buffalo fighters of VMF-221 for delivery in Oahu. "
So the Saratoga was not anywhere near Pearl Harbor on Dec 7th and had no planes of any kind on board having just left the Bremerton navy yard after a nearly year long modernization and refit.
Of the 7 US Carriers only 3 (including the Saratoga) were in the Pacific, the other 4 were in the Atlantic. So all four of them could be said not to be at Pearl Harbor, doesn't mean they didn't have Wildcats on board.

I would note that Grumman was increasing production and built another 332 F4Fs in the first 4 months of 1942 and for the rest of the year production never dropped below 100 per month.

The RN got about half the 1940/41 production.

Conslaw · May 20, 2019

If it had been a high enough priority, and had there been a willingness to accept that better is the enemy of "good enough", a limited production version of the XF4U could have been available in 1941. Consider that the XF4U's first flight was in May 1940. The prototype for the A6M Zero first flew in April 1939, and 13 service-test units went into combat late summer 1940. An equivalent timeline for the Corsair would be fall 1941. Of course, this theoretical Corsair wouldn't be the one we know. It would be an extremely buggy 350+ MPH fighter which could occasionally take off and land from a carrier without killing the pilot. It would be undergunned and probably would not have protected fuel tanks.

As to the 800 lb weight penalty of the R-2800 over the R-1830, the XF4U flew 405 MPH in October 1940. Even with 1800 nominal horsepower that gives it a cushion of speed to lose in the transition from prototype to in-service fighter and still top 350 mph.

Kevin J · May 20, 2019

Conslaw said:
If it had been a high enough priority, and had there been a willingness to accept that better is the enemy of "good enough", a limited production version of the XF4U could have been available in 1941. Consider that the XF4U's first flight was in May 1940. The prototype for the A6M Zero first flew in April 1939, and 13 service-test units went into combat late summer 1940. An equivalent timeline for the Corsair would be fall 1941. Of course, this theoretical Corsair wouldn't be the one we know. It would be an extremely buggy 350+ MPH fighter which could occasionally take off and land from a carrier without killing the pilot. It would be undergunned and probably would not have protected fuel tanks.

As to the 800 lb weight penalty of the R-2800 over the R-1830, the XF4U flew 405 MPH in October 1940. Even with 1800 nominal horsepower that gives it a cushion of speed to lose in the transition from prototype to in-service fighter and still top 350 mph.

Sounds like a deathtrap. I think I'd prefer to be flying a Douglas Dauntless as a fighter.

Shortround6 · May 20, 2019

Ugh, guys
XF4U-1 that flew in 1940

Guns in cowl and one gun in each wing. cockpit about 3 ft further forward than production planes. Fuselage tank nonexistent, No fuel tanks were self sealing.
about 397 other "minor" changes before production.

BTW the prototype did NOT use a single stage engine. It used either the R-2800-X2 engine or the R-2800-X4 (at different times).
While take-off for the X-2 was 1850hp at 26000rpm it was rated at 1500hp at 17,500ft at 2400rpm, I am guessing in high gear ( it did have two stage engine).
The X4 was good for the same 1850hp at 2600rpm for take-off but was rated at 1600hp at 2400rpm at 3500ft, 1540hp at 2400rpm at 13,500ft, and 1460hp at 2400rpm at 21,500ft.
These are all "Normal" power or max continuous (1 hour rating or longer).

The -5 engine in the B-26 was rated at 1450hp at 2400rpm at 13,000ft. "Normal" power.

Good luck getting a 350mph airplane at 14-16,000ft. using the -5 engine.
A production F4U-1 did just under 370mph at 15,000ft using 1625hp and just under 390mph using 1800hp at 15,000ft. in one test,
British claim about 365mph at 15,000ft using full military power. (about 1800hp). I have no idea why the 20+mph difference.

GrauGeist · May 21, 2019

Kevin J said:
With a first flight date of May 29th 1940, it seems to me that it would be very unlikely that the Corsair could have seen operational service any time in 1941. Maybe if the Hellcat rather than the Skyrocket had flown first in 1940 with a single stage R-2800 then maybe maybe 1941, but at Pearl Harbour there was only one carrier operating the Wildcat, so does the Wildcat get canned?

The USS Ranger received F4F-3s in December 1940.
By 7 December 1941, many of the USN's carriers had the F4F, like the Yorktown, Wasp, Enterprise, Lexington, Saratoga and Hornet.

Conslaw · May 24, 2019

Shortround6 said:
I don't think it makes much difference, Both the P & W aux stage and the GE turbocharger were somewhat less than ideal (lower efficiency) at this point. The whole idea of the turbo at this point in time was try to duplicate sea level conditions at higher altitudes so at low altitude the waste gate is wide open and the turbo is "idling" providing little or no boost.
Of course at low altitude the P & W auxiliary supercharger is not clutched in either so it is not providing any boost or creating any heat in the intake tract.

You don't get any additional power at low altitude.

It is not until either the Aux supercharger is clutched in or the turbo engine gets to around 3700-4000ft that the waste gate will begin to close and provide any boost to the engine that intercoolers have any role at all. On a turbo engine the army's goal for the intercooler was to keep the intake air from exceeding 100 degrees F at the inlet to the carburetor.

The turbo doesn't take any power from the engine to drive so you gain there, the question is what point does the rise in intake temperature come into play.

So in those days turbocharging was only/primarily used to get sea level performance at altitude? Of course geared supercharger were already used to enhance sea level performance, when did things change and turbochargers get unleashed at low level? Now turbocharged cars are ubiquitous.

1941: the best case for 350+ mph CV fighters?

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