F6F Hellcat vs. P-47 Thunderbolt

[tomo pauk]

The F6F exists only because the F4U initially was a failure. It couldn't land on a carrier until the British devised ways to do so.

Not true x2.

If the F4U was able to land on a carrier the moment it entered service, the Navy would've rejected the Hellcat, since the F4U was not only superior in every aspect of dogfighting performance (speed, climb, turn and roll) but also was more suited for dive bombing.

Your opinion.

By September 1944, when the 150 octane fuel was introduced, P-47 was faster at most altitudes, and climbs better up high.

Not true.

Not a single flight manual mentioned the g limit for P-47s, which implies it is so great that it is impossible to reach (indeed, at sea level it has a top IAS speed of three times the stall speed, meaning it can pull 9g, any higher it will stall while attempting to do so).

...
If I am given the option I'll fly the F6F.
...

Per British wartime data, ultimate G load for P-47 was 12G, same as P-51. The garbage aircraft that you would fly was rated at 13.5 G.

 

[Dawncaster]

Grumman's tests showed that the F4U was faster down low because it did not have the provisions to prevent icing that they considered to be essential. Their high altitude tests showed that most of the speed advantage of the F4U at altitude was due to airspeed indicator error!

Corky Meyer's that article was his - Grumman Test Pilot's opinion. That's not what Grumman's test 'showed'. When compared under equivalent conditions, F4U was faster than F6F in USN and TAIC comparision reports with corrected speed.

Corky Meyer described the characteristic that normally exist as if they were something special. But the different IAS reads are not confined between F4U and F6F. It's common. Spitfire and Tempest also have different IAS reading tables, as were the P-47 and P-51, Yaks and MiGs, and etc. Even if they are flying at the same speed, the indicated air speed will be different. After correction for standard atmosphere, different IAS reading was meanless. As he wrote at the end of the article, he seems to have a little baised. He claims that both fighters 'SHOULD' have the same performance because they have the same engine, propeller, wing span, and gross weight. But In fact, the early F4U-1 had lighter gross weight, lower drag, shorter wing span, different propeller blades and different altitude performances. Contrary to his claim, F4U-1 BuNo 17781 was just raised cabin type F4U-1, not F4U-1D. If the F4U-1 was at a supercharger shift altitude and it had old propeller blades with early troublesome supercharged engine, it's not unusual for the F6F to be that fast as F4U - Especially If the F6F was less loaded and it's weight was light as F4U-1's gross weight. However, most of the problems in F4U's engine were almost solved when F6F arrived on the solomon, and most of the flight tests were done with similar load condition(ex. overload fighter), So F6F was generally slower than F4U in practical condition. even F6F-5 was slower than F4U-1D in comparison flight in all tested altitudes with corrected speed.

 

[Reluctant Poster]

I think the P-51 having more ground kills was very much a case of a LOT more opportunity. There are a LOT of airfields around Europe compared with the ones lying around in the Pacific Ocean. Since the Pacific is mostly water, the opportunity for ground kills, say, on the way home from a mission, was slight to nonexistent. That being said, had the two planes been reversed in use, I'm sure the F6F in Europe would have had a lot of ground kills, but maybe fewer at high altitude since it wasn't a high-altitude fighter.

I am not much for "which one is better" arguments, normally, but I think the F6F was to the US Navy what the P-51 was to the USAAC / USAAF, a top pick that proved it's worth many times over. The P-47 was very probably our best very-high altitude fighter, but the P-51 wasn't too far off, even there. No WAY the F6F was going to compete at 35,000 feet but, at 10,000 feet, I'd pick the Hellcat for dogfighting.

Ground kills by the 8th AF are the most overrated stat of WWII. 2/3 of them occurred in the final 6 weeks of the war when the Luftwaffe had ceased to exist. Destroying aircraft that would never fly again was a waste of resources, in particular young pilots lives.

 

[Joe Broady]

Grumman said that the USN gave them a F4U and told them that the USN only wanted one fighter type, and to get the Hellcat performance up to that of the F4U. Grumman's tests showed that the F4U was faster down low because it did not have the provisions to prevent icing that they considered to be essential. Their high altitude tests showed that most of the speed advantage of the F4U at altitude was due to airspeed indicator error!

Let's see how long time Grumman test pilot Corky Meyer tells the story. I have trimmed the quotes here and there to tighten the focus.

"In the desperate climate of World War II, the Navy decided that the easiest, quickest and least costly way to tweak the utmost performance out of its fighter planes would be to let rival manufacturers test the latest versions of each other's products. So it was in the summer of 1943 when the Navy delivered into Grumman hands the newest Corsair (F4U-1D Buno 17781)...

"Grumman's specific orders from the Navy were to improve the Hellcat's speed by 20 knots and put better ailerons on it so that it would compare favorably to the incomparable Corsair...

"We were also pleased to learn that we had not been singled out for the harassment of our sterling product when we heard that Chance Vought, our friendly competitor from the other side of the Long Island Sound, was also sent an F6F-3 Hellcat and ordered to improve Corsair visibility, cockpit internal layout, stall characteristics, and also redesign the landing gear oleos...

"In my first flight I discovered that the Corsair did indeed indicate 20 knots faster and did have really smooth and powerful ailerons compared to our Hellcat...

"To simplify the evaluation and data reduction, we decided to test fly the Hellcat and the Corsair in close formation. Performance could then be compared directly at the critical altitudes of the main stage, high and low blower altitudes of the engine's superchargers, and from cruise to high speed level flight with water injection in actual comparison instead of complex calculation...

"Except for the Corsair having a 15 knot actual speed advantage over the Hellcat in the main sea-level supercharger stage, both fighters had almost exactly the same speed both low and high blower from 5000 feet altitude up to service ceiling! ...

"The reason the Corsair was faster in the main stage blower was that its engine was provided with ram air coming in directly from the forward facing wing duct into the carburetor, whereas the Hellcat had the carburetor air coming in from the accessory compartment of the fuselage just behind the engine, with no ram air effect... Our engineering department defended their position because taking the warmer air for the main stage blower would prevent inadvertent carbureter icing engine failures.

"After noting the 20 knots indicated airspeed difference that had caused all the 'lower performance' ruckus for our Hellcat, we eagerly decided to change the airspeed system so that it would read even with the Corsair when they were in formation... We liked our simple and less complicated airspeed system, with the static and dynamic orifices on the same boom, but we decided to go whole hog and put the static orifice on the fuselage like the Corsair to tailor the system to read 20 knots higher."

But they made a mistake by using only one orifice. Pax River discovered a side slip in landing configuration could drop the indicated airspeed to zero! As the senior engineering test pilot, Meyer took the blame for missing that. Grumman's solution was a dual orifice system like the Corsair. "That was the last we heard of the Hellcat's performance gap with the Corsair."

He admits Grumman could not match the "delightful low forces and high rolling performance the Corsair had so ably demonstrated." Their engineers tried everything, even copies of the Corsair ailerons, but the Hellcat still couldn't match the Corsair roll. The problem was the higher lateral stability inherent in its wing design. And a new wing was out of the question at the height of the war. Later, when spring tabs were introduced in the -5 Hellcat and retrofitted to the -3, they made up much of the deficit.

Back to the airspeed, I view the Meyer account with some skepticism. Wasn't the Navy aware that you can't compare speeds without correcting for position error? (In those days I think it was often called "installation error.") On the other hand, the airspeed correction tables in the Hellcat pilot handbook are consistent with his story of Grumman's airspeed tweak. At all speeds the -3 indicates lower than CAS, and the -5 higher than CAS. At an efficient cruise speed of 140 knots, the -3 indicates 13 knots lower than CAS and the -5 indicates 7 knots higher. At 200 knots (as high as the table goes) the numbers are 14 and 17, respectively.

References:

Corwin Meyer and Steve Ginter, "Grumman F6F Hellcat," 2012.

"Pilots Handbook of Flight Operating Instructions for Navy Models F6F-3, F6F-3N, F6F-5, F5F-5N Airplanes" (year not shown)

 

[AlfaKiloSierra]

If you say the P-47 after September 1944 was not faster at all altitudes, at what altitude can the F6F outrun the P-47?
Second, how do you actually reach 13.5G in an F6F?
Third, show me all your sources. All the factual claims I made are true and verifiable on wwiiaircraftperformance.org which contains a good amount of speed vs altitude graphs. I refered to them before I commented.

 

[fubar57]

Sounds like a good site. Everyone here should check it out

 

[tomo pauk]

(figured this is a reply to my post)

If you say the P-47 after September 1944 was not faster at all altitudes, at what altitude can the F6F outrun the P-47?

???
Who said the F6F can outrun the P-47?

Second, how do you actually reach 13.5G in an F6F?

No, not me, this is what pilots do (or do not)?
At any rate - if you have problems with ww2 historical data, take it with the people that wrote it.

Third, show me all your sources. All the factual claims I made are true and verifiable on wwiiaircraftperformance.org which contains a good amount of speed vs altitude graphs. I refered to them before I commented.

I've never heard of that site, nor about the people that run it. I'm just pulling the numbers from my pocket, FTW.

 

[AlfaKiloSierra]

Let's see how long time Grumman test pilot Corky Meyer tells the story. I have trimmed the quotes here and there to tighten the focus.

"In the desperate climate of World War II, the Navy decided that the easiest, quickest and least costly way to tweak the utmost performance out of its fighter planes would be to let rival manufacturers test the latest versions of each other's products. So it was in the summer of 1943 when the Navy delivered into Grumman hands the newest Corsair (F4U-1D Buno 17781)...

"Grumman's specific orders from the Navy were to improve the Hellcat's speed by 20 knots and put better ailerons on it so that it would compare favorably to the incomparable Corsair...

"We were also pleased to learn that we had not been singled out for the harassment of our sterling product when we heard that Chance Vought, our friendly competitor from the other side of the Long Island Sound, was also sent an F6F-3 Hellcat and ordered to improve Corsair visibility, cockpit internal layout, stall characteristics, and also redesign the landing gear oleos...

"In my first flight I discovered that the Corsair did indeed indicate 20 knots faster and did have really smooth and powerful ailerons compared to our Hellcat...

"To simplify the evaluation and data reduction, we decided to test fly the Hellcat and the Corsair in close formation. Performance could then be compared directly at the critical altitudes of the main stage, high and low blower altitudes of the engine's superchargers, and from cruise to high speed level flight with water injection in actual comparison instead of complex calculation...

"Except for the Corsair having a 15 knot actual speed advantage over the Hellcat in the main sea-level supercharger stage, both fighters had almost exactly the same speed both low and high blower from 5000 feet altitude up to service ceiling! ...

"The reason the Corsair was faster in the main stage blower was that its engine was provided with ram air coming in directly from the forward facing wing duct into the carburetor, whereas the Hellcat had the carburetor air coming in from the accessory compartment of the fuselage just behind the engine, with no ram air effect... Our engineering department defended their position because taking the warmer air for the main stage blower would prevent inadvertent carbureter icing engine failures.

"After noting the 20 knots indicated airspeed difference that had caused all the 'lower performance' ruckus for our Hellcat, we eagerly decided to change the airspeed system so that it would read even with the Corsair when they were in formation... We liked our simple and less complicated airspeed system, with the static and dynamic orifices on the same boom, but we decided to go whole hog and put the static orifice on the fuselage like the Corsair to tailor the system to read 20 knots higher."

But they made a mistake by using only one orifice. Pax River discovered a side slip in landing configuration could drop the indicated airspeed to zero! As the senior engineering test pilot, Meyer took the blame for missing that. Grumman's solution was a dual orifice system like the Corsair. "That was the last we heard of the Hellcat's performance gap with the Corsair."

He admits Grumman could not match the "delightful low forces and high rolling performance the Corsair had so ably demonstrated." Their engineers tried everything, even copies of the Corsair ailerons, but the Hellcat still couldn't match the Corsair roll. The problem was the higher lateral stability inherent in its wing design. And a new wing was out of the question at the height of the war. Later, when spring tabs were introduced in the -5 Hellcat and retrofitted to the -3, they made up much of the deficit.

Back to the airspeed, I view the Meyer account with some skepticism. Wasn't the Navy aware that you can't compare speeds without correcting for position error? (In those days I think it was often called "installation error.") On the other hand, the airspeed correction tables in the Hellcat pilot handbook are consistent with his story of Grumman's airspeed tweak. At all speeds the -3 indicates lower than CAS, and the -5 higher than CAS. At an efficient cruise speed of 140 knots, the -3 indicates 13 knots lower than CAS and the -5 indicates 7 knots higher. At 200 knots (as high as the table goes) the numbers are 14 and 17, respectively.

References:

Corwin Meyer and Steve Ginter, "Grumman F6F Hellcat," 2012.

"Pilots Handbook of Flight Operating Instructions for Navy Models F6F-3, F6F-3N, F6F-5, F5F-5N Airplanes" (year not shown)

There is a discrepancy with the reports available on wwiiaircraftperformance.org, I don't know what happened there. Both the USAAF and NACA performed testings and charted their high speeds in terms of True Airspeed instead of Indicated Airspeed/Calibrated Airspeed, which means it is more reliable, but I don't know how much instrumentation error can result from positioning of the pitot-static assembly. I think this account is surely interesting.

 

[AlfaKiloSierra]

(figured this is a reply to my post)


???
Who said the F6F can outrun the P-47?



No, not me, this is what pilots do (or do not)?
At any rate - if you have problems with ww2 historical data, take it with the people that wrote it.



I've never heard of that site, nor about the people that run it. I'm just pulling the numbers from my pocket, FTW.

The value of 13.5G is completely meaningless, the F6F's top speed in indicated airspeed is not sufficient to generate a turn that reaches 13.5G. No P-47 was recorded breaking up in flight, neither was any F6F, as no pilot is willing or able to pull more than 9G. In the P-47 it is impossible to exceed 9G without diving. In the F6F, which has a lower stall speed, doing so may be possible but without the use of a G-suit, the pilots cannot fly properly. wwwaircraftperformance.org is run by whoever it is run by, but since all the data I pull from it are from primary sources (written by the RAF, the USAAF or the NACA), it is 100% reliable. Plus I only use the hard data, as in their speed vs altitude and climb vs altitude graphs. What numbers you pulled from your pocket cannot be verified anywhere other than other forums and secondary sources. Now, as to who said the F6F can outrun the P-47, I said the P-47 can outrun the F6F at all altitudes after September 1944, and you replied not true. That person is you.

 

[tomo pauk]

The value of 13.5G is completely meaningless, the F6F's top speed in indicated airspeed is not sufficient to generate a turn that reaches 13.5G. No P-47 was recorded breaking up in flight, neither was any F6F, as no pilot is willing or able to pull more than 9G. In the P-47 it is impossible to exceed 9G without diving. In the F6F, which has a lower stall speed, doing so may be possible but without the use of a G-suit, the pilots cannot fly properly.

Again - if you have problems with historical data, take it to the people who wrote the stuff.
High G loadings were far easier to attain when flying fast, than when flying slow.

wwwaircraftperformance.org is run by whoever it is run by, but since all the data I pull from it are from primary sources (written by the RAF, the USAAF or the NACA), it is 100% reliable. Plus I only use the hard data, as in their speed vs altitude and climb vs altitude graphs. What numbers you pulled from your pocket cannot be verified anywhere other than other forums and secondary sources.

That was my attempt at a tongue-in-cheek joke.

Now, as to who said the F6F can outrun the P-47, I said the P-47 can outrun the F6F at all altitudes after September 1944, and you replied not true. That person is you.

Let's take a look:

P-47 offered many advantages that the P-51 didn't have, namely strong firepower and protection for the pilot. By September 1944, when the 150 octane fuel was introduced, P-47 was faster at most altitudes, and climbs better up high.

 

[AlfaKiloSierra]

Again - if you have problems with historical data, take it to the people who wrote the stuff.
High G loadings were far easier to attain when flying fast, than when flying slow.



That was my attempt at a tongue-in-cheek joke.



Let's take a look:

Take it to who wrote the stuff. Now, who wrote it? You still haven't told me yet. Then, if you don't believe my claim the P-47 was faster than P-51 at most altitudes, go look at the speed vs altitude graph of the P-47 and of the P-51. The P-51 outruns the P-47 around its first speed supercharger critical altitude, nowhere else.

 

[tomo pauk]

Take it to who wrote the stuff. Now, who wrote it? You still haven't told me yet.

I've had a word with my neighbour, he has a time machine, and is well connected with those funky British boffins of the 1940s. They just write down anything I need to prove my point.

Then, if you don't believe my claim the P-47 was faster than P-51 at most altitudes, go look at the speed vs altitude graph of the P-47 and of the P-51. The P-51 outruns the P-47 around its first speed supercharger critical altitude, nowhere else.

A-ha, now the P-51D is suddenly faster than P-47D at one altitude band, despite claiming otherwise in post #212.

 

[AlfaKiloSierra]

I've had a word with my neighbour, he has a time machine, and is well connected with those funky British boffins of the 1940s. They just write down anything I need to prove my point.



A-ha, now the P-51D is suddenly faster than P-47D at one altitude band, despite claiming otherwise in post #212.

I said most, didn't say all. And you know that.

 

[tomo pauk]

I said most, didn't say all. And you know that.

Yes, you did. I apologize.

 

[BiffF15]

The value of 13.5G is completely meaningless, the F6F's top speed in indicated airspeed is not sufficient to generate a turn that reaches 13.5G. No P-47 was recorded breaking up in flight, neither was any F6F, as no pilot is willing or able to pull more than 9G. In the P-47 it is impossible to exceed 9G without diving. In the F6F, which has a lower stall speed, doing so may be possible but without the use of a G-suit, the pilots cannot fly properly. wwwaircraftperformance.org is run by whoever it is run by, but since all the data I pull from it are from primary sources (written by the RAF, the USAAF or the NACA), it is 100% reliable. Plus I only use the hard data, as in their speed vs altitude and climb vs altitude graphs. What numbers you pulled from your pocket cannot be verified anywhere other than other forums and secondary sources. Now, as to who said the F6F can outrun the P-47, I said the P-47 can outrun the F6F at all altitudes after September 1944, and you replied not true. That person is you.

AlfaKiloSierra,

Welcome to the site!

Also be advised a pilot can pull more than 9 G's as I averaged at least one per year for the entire time I flew the Eagle. Ive seen guys pull in excess of 10, and have flown jets that had more than 11 put on them. That really ticks the crew chiefs as the engines get pulled so they can x-ray the motor mounts amongst other checks.

The air show performers pull more than that in some of their planes, and that is without a G suit. I spoke with Sean Tucker after he got a ride in an F-18 (7.3 G jet). He was amazed at the difference between sustained G and instantaneous (not sustained).

Cheers,
Biff

 

[P-39 Expert]

Sounds like a good site. Everyone here should check it out

Is that in the internet?

 

[pbehn]

The value of 13.5G is completely meaningless, .

It is not meaningless. Biff has answered in terms of the pilot AND the air frame. If a structure whatever it is has a maximum of 6G and you turn at 6G then you probably damage it. If you repeatedly fly to 5G you probably also damage it. The limit is based on yield strengths, if you go over the yield stress you permanently deform the structure, but also if you repeatedly apply high loads you can damage it, with the materials used in aircraft even low loads repeatedly applied and removed can cause failure. The UK V bombers had their service lives drastically reduced simply by having to fly at low altitude instead of the high altitude they were designed for, no violent turning at all.

 

[MIflyer]

Yes, the F4U took the air intake at the wing root where it could get to the engine very easily.

Now, look at what Grumman did with the F8F.

 

[pinsog]

Hello Gentlemen. AlfaKiloSierra is new to the site so everyone should probably not use 'tongue in cheek' responses since he doesn't realize if you are teasing or not. Those of us that have been here a while know many of the respected sites we use to prove or disprove a point but he may not realize this. I just hate to see a possible new member leave the site if we are too rough on him at the beginning. All of us were new here at one time. I can't tell you how much I thought I knew that was plain wrong and how much I have learned from so many on this site.

Respectfully submitted,
Pinsog

 

[wuzak]

The value of 13.5G is completely meaningless

The 13.5G figure represents the ultimate load for the airframe, and indicates the strength of the airframe.

The design load was, probably, 9G, with a factor of safety of 1.5.

Doubtful the F6F could ever get to 9G in normal manoeuvring. I'm sure the extra strength was designed in to cope with carrier landings.