F6F vs F4U Research

[Widewing]

A few useful and entertaining sources...

My friend Barrett's books...




Does anyone know that the Navy tasked Grumman with fixing the F4U's oleo bounce problem? Grumman engineered new valving that reduced the over-damping and tamed the Corsair's bouncing. Corky Meyer was the project test pilot. Grumman did extensive flight testing of F4Us, and Vought flew many Hellcats.

The F6F series (-3 and -5) were preferred on the carriers for several reasons. The Hellcat was far superior around the boat. Easier to fly, better stall characteristics. That was a major advantage in the Navy's view. Performance wise, the F4U was faster at low level due to direct carb air ram. The F6F brought in carburetor air through the accessory section... No RAM. At altitude, there was little difference in speed. All major tests show the F6F-5 being capable of over 400 mph at critical altitude. Most commonly found data tests show either Normal Power or MIL power speeds. The F6F-5 could manage 391 mph at 23,100 feet in MIL Power, 409 mph at 21,600 feet in WEP (TAIC Report 17). From the same test report, in comparison, the F4U-1D could attain 413 mph at 20,400 feet.

See the report here:
http://www.wwiiaircraftperformance.org/japan/ptr-1111.pdf

There's much test data for both types here:
http://www.wwiiaircraftperformance.org/

Post war analysis deemed the survivability of the F6F to be slightly better than the F4U. The F4U-4 was a major improvement over the F6F-5, except in range. However, both Grumman and the Navy elected to drop the competing XF6F-6 program for the far more capable F8F-1. As fighters go, the F4U-4 was one of the best, if not truly the best fighter to see combat during the war. The F8F-1, which missed combat by no more than a week, was on another plateau altogether. It out-performed the F4U-4 in every category of air to air combat, and did so with considerable margin. However, the F4U-4 was the better fighter-bomber. As Korea would show 5 years later, fighter-bombers were of greater importance, especially when the fleet fighters were then jets (F9F and F2H). F8Fs saw no combat in Korea, but the mighty F4U-4s (-4 and -4B) were in from almost day one, and gave outstanding service until replaced with later models.

As to your paper... The primary advantage the F6F held over the F4U in combat was that the F6F was in the thick of it all of the time after July of 1943. Before the F4U went aboard ships in numbers (F4U-2 night fighters were flying from carriers in 1943), they were generally confined to land bases. That restricted access to the enemy. On the other hand, the F6F was brought to the enemy... That must not be overlooked as it is a critical factor in the F6F's domination as the premier carrier fighter until early 1945.

[Oldman731]

The primary advantage the F6F held over the F4U in combat was that the F6F was in the thick of it all of the time

This is probably the basic conclusion of your paper.

- oldman

[Karnak]

Does anybody know why the British kept developing the Seafire after the F6F and F4U became available to them?  The Seafire never seemed like a great idea, just an understandable one when it was the best thing they could get.  I would have thought, particularly due to its horrible ship handling problems, that the Seafire should have been phased out ASAP once the F6F and F4U were made available to the Royal Navy, instead it seems they almost doubled down on the Seafire with 1200 of the contemporary Mk IIIs and even postwar development ending with the Mk 47.

Why?  It seems stupid.

[Captain Virgil Hilts]

Does anybody know why the British kept developing the Seafire after the F6F and F4U became available to them?  The Seafire never seemed like a great idea, just an understandable one when it was the best thing they could get.  I would have thought, particularly due to its horrible ship handling problems, that the Seafire should have been phased out ASAP once the F6F and F4U were made available to the Royal Navy, instead it seems they almost doubled down on the Seafire with 1200 of the contemporary Mk IIIs and even postwar development ending with the Mk 47.

Why?  It seems stupid.

Probably because it was a British plane.

[Karnak]

Probably because it was a British plane.

Perhaps, but it isn't like they didn't use lots of American built aircraft on their carriers.  It seems like it would have been significantly better to have standardized on the F4U or F6F, both of which were used by the Royal Navy and both of which are significantly superior to anything British until the Sea Fury.

That said, humans are not always rational.

[Captain Virgil Hilts]

Perhaps, but it isn't like they didn't use lots of American built aircraft on their carriers.  It seems like it would have been significantly better to have standardized on the F4U or F6F, both of which were used by the Royal Navy and both of which are significantly superior to anything British until the Sea Fury.

That said, humans are not always rational.

During the war is one thing, after the war is another.  Peacetime sharing of aircraft was not as common then as it is now. Even during the war, the British were extremely concerned with their economy after the war, especially with regard to employment. They had a great fear that after the war they'd return to extremely high unemployment.

They may also have felt, as the U.S. Navy did, that the piston engine propeller driven fighter had reached its twilight, so if they were going to buy some obsolete fighters, they might as well buy them from a British company.

[icepac]

Who needs the F4U when you have the seafire 47.

[earl1937]

I've got some good material to work with, the problem is what they're telling me:  According to the postwar survey the F6F had a big edge in A-A k/d, an operational loss rate only 60% that of the Corsair (huge), and a significantly lower loss rate in air to ground missions of comparable profile.  Also, it seems the F6F was a little better in mx requirements though this is still a loose end requiring more sources before going "airtight."  

This brings me three different thoughts:
1. How does one define "technical superiority" in the first place?  Operational capability or operational effectiveness?
2. The Corsair does seem to have had more room for development but there is not as much weight here as first thought. This brings me to point
3. How much did contract politics play into the Navy's choices?  If the F8F was so great, why did the Corsair continue developing alongside that Grumman as well?

Don't forget to remember one of the big problems with the F4U series of aircraft was the difficulty of landing on carriers! One of the problems was the "oleo" struts which the landing gear was assembled with. The first ones had way to much bounce in them, as it was originally designed to operate off of ill prepare runways in the SW Pacific, so they stiffen them up, by changing the relief valves in the oleo system, as pointed out in another answer in this thread correctly pointed out. Then the Korean conflict came along and the F4U's could carry a lot of ords into the Korean conflict, operating off carriers close to shore. As the "Sandy"(Skyraider), wasn't yet developed to its full potential, and a large inventory of F4U's were on hand, time and history had something to do with the length of life of the "Corsair". Politics, in my view, played a part the way things happend, because of the exploits of "Richard Bong". With the American public yearning for good news from the "war", It was a lot easier for the "politicans" in Washington to vote to extend the production life of the "Corsair". Another point to remember, while the Navy flew F4U's, it was primarily a Marine aircraft, which could operate off of rough runways on the Islands in the Pacific, better than the F6F.(my opinion). The reason I say that is the length of the fuseledge of F4U series made for better handing on rough runways than the shorter F6F.

[Mister Fork]

I thought the French used F6F Hellcats and F4U-7 Corsair, well into post-war on their carrier 'Arromanches'. Might be good to check out their use of the Hellcat and the Corsair - probably used them pre-US involvement in the IndoChina war and against the Viet Minh regime.

[Noir]

I thought the French used F6F Hellcats and F4U-7 Corsair, well into post-war on their carrier 'Arromanches'. Might be good to check out their use of the Hellcat and the Corsair - probably used them pre-US involvement in the IndoChina war and against the Viet Minh regime.

again that needs checking, but I'm not sure we fielded F6F's, only F4U's

[Noir]

nevermind a quick wiki check proved me wrong

The French Aéronavale was equipped with F6F-5 Hellcats and used them in Indochina.

[Noir]

Does anybody know why the British kept developing the Seafire after the F6F and F4U became available to them?  The Seafire never seemed like a great idea, just an understandable one when it was the best thing they could get.  I would have thought, particularly due to its horrible ship handling problems, that the Seafire should have been phased out ASAP once the F6F and F4U were made available to the Royal Navy, instead it seems they almost doubled down on the Seafire with 1200 of the contemporary Mk IIIs and even postwar development ending with the Mk 47.

Why?  It seems stupid.

maybe there wasn't enough production to supply the british and the US in the same time? Also weren't regular spitfires able to be converted to carrier operation?

[Karnak]

maybe there wasn't enough production to supply the british and the US in the same time? Also weren't regular spitfires able to be converted to carrier operation?

No, the Mk III, by far the most common Seafire with 1200 built during the war, was a dedicated carrier plane with folding wings and arrester gear.  Only the Seafire Mk Is were converted from Spitfire Mk Vs.

It is really those 1200 Mk IIIs that don't make a lot of sense to me.  1200 is a fairly large number for a carrier fighter and during that entire time the F4U and F6F were available.

[Shuckins]

I prefer the assessments of two test pilots when comparing Hellcat to Corsair.  Corky Meyer and Cpt. Eric Brown of the Royal Fleet Air Arm both have vast experience in test flying aircraft, with Brown having no dogs in the hunt when comparing two different American aircraft.  Widewing's assessments on these boards pretty much mirror theirs.

Corky and other Grumman test pilots, at the Navy's insistence, flew the F6F-3 and F4U-1D in side-by-side comparisons to assess the apparent differences between the two aircraft.  Chance-Vought's test pilots were also provided with a -3 Hellcat to compare it to the Corsair.

Corky states that the Navy wanted them to study the Corsair's design to find ideas to help correct two faults in the Hellcat's design:  an indicated speed difference of 20 knots less airspeed at nearly all altitudes;  and a loss in roll-rate from 70 degrees a second at low to moderate airspeeds to about 40 degrees at speeds in excess of 300 knots.  Chance-Vought had to study the Hellcat to help rectify the Corsair's horribly stiff oleo landing gear and abysmal low-speed stall characteristics.

While the Corsair proved to be 20 knots faster at low-level in the main-stage blower, as Widewing stated, the air-speed indicator of the Corsair showed that it was 20 knots faster than the Hellcat even at both aircraft's rated altitude, even when they were closely stabilized in flight (read "identical" air-speeds).  As it turned out, the positioning of the Hellcat's static and dynamic orifices consistently read 20 knots slower than that of the Corsair even when their flight speeds could be seen to be identical.  A repositioning of the orifices to the same positions that they were in on the Corsair solved the problem.

Capt. Brown flew the Hellcat and Corsair extensively.  While he considered the Corsair to be a fine aircraft, he preferred the Hellcat when it came time to mix it up with the enemy.  His book "Duels in the Sky" contain some interesting one-on-one comparisons of Allied naval aircraft with their Axis opponents.  In a comparison between the Corsair and the FW-290 A4 he states that the FW could not be bested by the Corsair while the Hellcat was a better matchup for the German aircraft.

[Crash Orange]

The last two points are critical and often ignored. A plane has 0 performance if it is not in the war zone. F6F got there first (despite nearly 2 years head start of the F4U) and Grumman broke production records in order to fill squadrons with Hellcats. By the time Vought qualified the F4U to carrier operations and got around to produce more than a handful to arrive on carriers in numbers, they missed all the critical battles of the war.

The F4U was not there only if you consider "there" to be on carrier decks only. The F4U saw combat six months before the F6F did and flew about the same number of combat sorties during the war. Arguably the most critical air battles of the war after Midway were those of the Solomons Campaign, since that's when the IJNAF and IJAAF were chewed to pieces and lost all their veteran pilots. The F4U played if anything a greater role than the F6F in those battles. The deployment of F4Us was far more than "a handful" in 1943 and 1944 when they were operating almost exclusively from land. IIRC in Tom Blackburn's The Jolly Rogers he says that the Navy's reasons for keeping the F4U off carriers so long were more due to institutional than technical factors; in late 1943 he had trained his squadron to land on and take off from carrier decks with little difficulty and they did so without a single accident on one combat mission where they refueled on USS Bunker Hill.

The two planes racked up similar kill ratios against first-line enemy fighters (12:1 for the F4U and 13:1 for the F6F against the A6M, for example). Given that fact, I expect the main reason for the different overall kill ratios was that the F6F's earlier carrier deployment gave it more opportunities to intercept vulnerable bombers and to kill second-rate aircraft in raids on less active areas of the Pacific. So I would amend the last sentence above to "By the time the Navy deployed F4Us on carriers in numbers, they had missed the best chances to rack up easy kills against large numbers of more-or-less helpless opponents". At that point the primary mission for the F4U became ground support, at which it excelled.