Why was the F2G so "slow"

[SpicyJuan11]

Same as the thread title. Why was the F2G, despite the increase in power by almost 600HP (3,000HP vs 2,380HP of the F4U-4) and carrying two less machine guns, although still weighing 1,000 pounds heavier (10,249 lbs vs 9,205), the F2G was, according to Wikipedia, 15 mph slower (431 vs 446), almost had the same clime rate 4,400ft/min vs 4,360ft/min), had a worse ceiling, but had a better power to weight ratio empty (0.29HP/lb vs 0.258HP/lb). So what gives? Why wasn't the F2G a true "Super Corsair" but instead a failure?

 

[tomo pauk]

It was not a failure.
It was slower than the then-best F4U because it have had a 1-stage supercharger, vs. the F4U-4 with 2-stage S/C. As a consequence, the -4 have had more power past ~20000 ft, and much more past ~25000, and thus the -4 was faster. Similar was the thing with Spitfire IX and XII - the Mk.XII have had Griffon, but Mk.IX have had a 2-stage S/C on the Merlin (vs. 1-stage S/C on Griffon II), making the Mk.IX faster as altitude was increasing.

 

[Mike Williams]

According to the Bureau of Aeronautics Airplane Characteristics & Performance dated 1 Dec 1944, the F2G-2 V-Max Sea Level was 399 MPH. That's not bad for a late war piston aircraft. The F4U-4 Max SL speed was about 333 knots/383 MPH.

 

[tomo pauk]

People can take a look at SAC, CS, ACP, PD and other docs here: link

 

[glennasher]

Same as the thread title. Why was the F2G, despite the increase in power by almost 600HP (3,000HP vs 2,380HP of the F4U-4) and carrying two less machine guns, although still weighing 1,000 pounds heavier (10,249 lbs vs 9,205), the F2G was, according to Wikipedia, 15 mph slower (431 vs 446), almost had the same clime rate 4,400ft/min vs 4,360ft/min), had a worse ceiling, but had a better power to weight ratio empty (0.29HP/lb vs 0.258HP/lb). So what gives? Why wasn't the F2G a true "Super Corsair" but instead a failure?

That's still awfully fast for an aircraft designed to take off and land on a boat. We should always keep that in mind, they weren't built for a nice flight strip on a huge field, they were made to land on a postage stamp out in the ocean. To get 400 knots from a boat-based aircraft was a pretty big deal back then. That they were able to manage that back then is a pretty good thing.

 

[pbehn]

Apart from what others have said from the pictures I have seen the aerodynamics look awful, like a prototype lash up.

 

[33k in the air]

My understanding is that the F2G was intended to excel at low altitude speed for the purposes of intercepting lower-flying Japanese kamikaze aircraft. It's sea level maximum speed would seem to have achieved that intended goal.

 

[SpicyJuan11]

It was not a failure.
It was slower than the then-best F4U because it have had a 1-stage supercharger, vs. the F4U-4 with 2-stage S/C. As a consequence, the -4 have had more power past ~20000 ft, and much more past ~25000, and thus the -4 was faster. Similar was the thing with Spitfire IX and XII - the Mk.XII have had Griffon, but Mk.IX have had a 2-stage S/C on the Merlin (vs. 1-stage S/C on Griffon II), making the Mk.IX faster as altitude was increasing.

Thank you, that makes a lot of sense. Do you know of any proposals to mount a 2-stage supercharger or a turbocharger in the F2G? Any idea what the performance would look like?

 

[SpicyJuan11]

According to the Bureau of Aeronautics Airplane Characteristics & Performance dated 1 Dec 1944, the F2G-2 V-Max Sea Level was 399 MPH. That's not bad for a late war piston aircraft. The F4U-4 Max SL speed was about 333 knots/383 MPH.

That's still awfully fast for an aircraft designed to take off and land on a boat. We should always keep that in mind, they weren't built for a nice flight strip on a huge field, they were made to land on a postage stamp out in the ocean. To get 400 knots from a boat-based aircraft was a pretty big deal back then. That they were able to manage that back then is a pretty good thing.

Not good enough for the Navy, apparently. It's not that the F2G wasn't fast, it's that it wasn't fast enough, especially considering all the extra horsepower, which made me wonder why not.

 

[tomo pauk]

Thank you, that makes a lot of sense. Do you know of any proposals to mount a 2-stage supercharger or a turbocharger in the F2G? Any idea what the performance would look like?

The only 2-stage version of the R-4360 that I'm aware was the one considered for the XP-72 Superbolt. The auxiliary supercharger was to be located aft the cockpit, gear-driven by a long shaft (picture). The P-72 was supposed to do 500 mph.
Turboed R-4360 was used on US bombers.
To the best of my knowledge, there was no F2G with better S/C aboard, just the 1-stage integral unit.

 

[Koopernic]

The only 2-stage version of the R-4360 that I'm aware was the one considered for the XP-72 Superbolt. The auxiliary supercharger was to be located aft the cockpit, gear-driven by a long shaft (picture). The P-72 was supposed to do 500 mph.
Turboed R-4360 was used on US bombers.
To the best of my knowledge, there was no F2G with better S/C aboard, just the 1-stage integral unit.

From Wiki:
Note: Test pilot Tom Bellinger stated flatly that no XP-72 flights ever exceeded 500 mph. The dash 13 engine was not supercharged. With the planned but never installed (as Tomo noted) dash 19 engine (with a remote supercharger) rated at 3,650 HP at 25,000 ft. (3,000 HP at sea level) a top speed of 504 mph at approximately 25,000 feet was expected. Planned further development of the dash 19 engine was expected to yield approximately 4,000 hp and a speed of 540 mph at 25,000 ft.

 

[Shortround6]

They may have been exceeding the propellers capacity to transmit the power.
I believe there was work being done on counter rotating propellers?

 

[tomo pauk]

From Wiki:
Note: Test pilot Tom Bellinger stated flatly that no XP-72 flights ever exceeded 500 mph. The dash 13 engine was not supercharged. With the planned but never installed (as Tomo noted) dash 19 engine (with a remote supercharger) rated at 3,650 HP at 25,000 ft. (3,000 HP at sea level) a top speed of 504 mph at approximately 25,000 feet was expected. Planned further development of the dash 19 engine was expected to yield approximately 4,000 hp and a speed of 540 mph at 25,000 ft.

(my bold)
I've said the word "supposed" for a reason.
The bolded part is hurting my eyes, tanks to the article's author. Yet another myth to be busted.

 

[Koopernic]

They may have been exceeding the propellers capacity to transmit the power.
I believe there was work being done on counter rotating propellers?

Republic XP-72
They fitted the second prototype with a contra rotating prop but it was written of in a crash before it could be tested.

 

[SpicyJuan11]

From Wiki:
Note: Test pilot Tom Bellinger stated flatly that no XP-72 flights ever exceeded 500 mph. The dash 13 engine was not supercharged. With the planned but never installed (as Tomo noted) dash 19 engine (with a remote supercharger) rated at 3,650 HP at 25,000 ft. (3,000 HP at sea level) a top speed of 504 mph at approximately 25,000 feet was expected. Planned further development of the dash 19 engine was expected to yield approximately 4,000 hp and a speed of 540 mph at 25,000 ft.

Wow that's some wild horsepower and speed. Do you know how far in development the dash 19 was?

(By the way, did you get my PM?)

 

[Koopernic]

Wow that's some wild horsepower and speed. Do you know how far in development the dash 19 was?

(By the way, did you get my PM?)

Yes, sorry haven't answered yet, been thinking it through. Thanks

As good a source as any on the XP-72 is Joe Baugher's sight.
Republic XP-72

The XP-72 was cancelled. Range was too short and the P-80 was on its way.

 

[J4F-2]

The other major problem the F2G had was the F8F-1 which could do everything the F2G could and more, much more. It was lighter, smaller and faster, it could climb higher and faster and was faster at altitude using a proven engine, it was the biggest reason the F2G was cancelled.

 

[Shortround6]

Be very careful if using wiki as a source.

From Goodyear F2G Corsair - Wikipedia

". In addition, Grumman F8F Bearcat – a rival design that had also entered production – had performance comparable to the F2G, even though it was powered with the same engine as the original F4U."

Bolded part is wrong. The engine/s used in the F8F (there were several) were all single stage engines, the F8F-1 (and prototypes) used C series engines, The F4U-1 though the F4U-1D used B series engines with two stage superchargers, The F8F-2 used an "E" series engine (single stage) one of only two planes to do so. These late model engines used a better supercharger design than the older engines. The single stage Engine in the F8F-1 was good for 1700hp at 16,000ft without water. Original engine in the the F4U-1 was good for 1800hp at 15,500ft using low speed in the auxiliary supercharger without water. C series engine had less cooling drag for the same power.

You also had Vought working on the F4U-5 which first flew in Dec 1945. This was the other plane to fly with an "E" series engine only, it was the famous two stage three compressor sidewinder engine. It offered much better altitude performance than the F2G.

 

[tomo pauk]

The other major problem the F2G had was the F8F-1 which could do everything the F2G could and more, much more. It was lighter, smaller and faster, it could climb higher and faster and was faster at altitude using a proven engine, it was the biggest reason the F2G was cancelled.

Think you've mixed up the F8F-1 with the -2.
The biggest reason for cancellation of F2G was probably the end of ww2.

 

[newst]

Has everyone forgotten what direction the Navy was taking at the time? Think JET. It was likely that post-war engineering could have tweaked the F2G to some exciting performance numbers, but jet-powered aircraft were coming online, so why spend the time, effort, and money.