Was the F4U Seriously Considered for the European Theatre ?

[Timppa]

VF19 conducted combat operations in Corsairs from a US carrier on November 11, 1943.
January 9, 1944, VF(N)-101 ( F4U2s) began to conduct combat operations from Enterprise. AT NIGHT!
Don't those operations count as combat from a carrier? VF17 as well as VF(N)-101 did not learn to operate their Corsairs from carriers from the RN.

AFAIK (correct if I am wrong), VF-19 refuelled from a carrier, operating from a land base.
If one night fighter unit operated from a carrier before the RN, that is fine.
But if we are not talking about "Guinness World Records " -firsts, don't you agree, that the RN was the first user of the F4U in large scale from carriers. ?

BTW, British made the three crucial inventions, that made the jet carrier aviation possible.

 

[renrich]

The "myth" which is in question is that the RN "taught" the US how to operate Corsairs from carriers. It is not who operated the most Corsairs from carriers first. The USN knew that Corsairs could be operated from carriers and how to do it before the RN even got any Corsairs on carriers and the record amply supports that. The reason that the USN did not use Corsairs on carriers in great numbers until late in the war were twofold. Firstly Hellcat spares and supplies were already in the pipeline when VF17 became ready to deploy in Corsairs. Secondly the USN felt that the Hellcat at that time was safer to operate, especially with low time pilots, from carriers and the Hellcat had sufficient performance to get the job done. The decision then was made to deploy the Corsair in Marine and Navy land based units. Perhaps that was the correct decision at that time. Perhaps not. The Navy made numerous mistakes during WW2, among them being the decision to allow the British to dictate the six gun armament with less ammo per gun of the F4F4 which was later reversed. Perhaps the Corsair decision was another one. However, Grumman could build lots of Hellcats quickly and Vought could build quite a few Corsairs not quite as quickly and all were needed.

VF17, not 19, was landbased. They reinstalled tail hooks. Their pilots had not made any carrier landings in months. They flew out to the task force. Acted as the CAP, shot down 18.5 EA, lost two Corsairs, landed, all safely. Refueled, rearmed, launched and flew home. Seems to me that shows, in spades, that the navy could operate Corsairs in combat from carriers. The Corsairs in the Tirpitz raids had no EA contact. Thus no combat.

Operating night fighter missions in combat by Corsairs from one of the smaller fleet carrier decks in the PTO also seems to me to show the Corsair was ready for carrier duty. I sometimes wonder if what the Navy was doing on the front lines was kept secret from the bureaucrats back in the US. Those bureaucrats often made decisions which seemed to make little sense to the people actually engaged with the enemy.

In an earlier post, I mentioned that the RN pioneered a number of innovations in carrier ops and needed no "Myths" to prove their worth. Angled flight decks. steam catapults, mirror landing system to mention some.

 

[davparlr]

Did an F4U-1 have any performance advantage over the P-47 in mid/late 1943?

Except for range, the F4U-1, and the non-water F4U-1A, did not have an apparent advantage over the P-47B/C nor necessarily the German aircraft of 1943. Water injection for the F4U, which improved performance considerably, was not provided for regular operations until well into 1944. A look at the performance levels for speed and climb of the F4U-1, P-47B, Fw 190A-5, and Bf 109G at various altitudes reveals some interesting information.

5k ft
F4U 348 mph, 2500 ft./min
P-47 352, 2545
Fw 190 367, 3850
Bf 109 344, 4234
It is apparent that neither aircraft offers the pilot a lot to work with when fighting the Germans

10k
F4U 359, 2440
P-47 369, 2465
Fw 190 382, 3000
Bf 109 362, 3060
Performance is getting closer

15k
F4U 378, 2410
P-47 386, 2330
Fw 190 410, 2400
Bf 109 368, 3420

20k
F4U 383, 1910
P-47 402, 2080
Fw190 420, 2400
Bf 109 399, 3094
The turbo is starting to show results. Fw 190 is still impressive.

25k
F4U 388, 1420
P-47 420, 1800
Fw 190 416, 1890
Bf 109 397, 2244
P-47 is showing its muscles

30k
F4U 363, 940
P-47 426, 1400
Fw 190 379, 1122
Bf 109 400, 1625
F4U and fw 190 have checked out at this altitude.

Some apparent conclusions:
While it had range for escort, the F4U-1 without water would have struggled against the German aircraft listed at all altitudes. Its performance was closer to the Fw 190A-3. The water injected, but shorter ranged, F4U-1D, which didn't appear until 1944, was more equivalent to the A-5.

Up to 15k ft., the F4U-1 and the P-47B were effectively equal in speed and climb. Above 15k ft., the P-47s flat-rated engine was starting to pull away. The F4U should out accelerate the P-47, roll rates seems similar, initial dive benefits the F4U while the P-47 has a higher dive speed. Profile drag coefficient benefits the P-47. All in all, below 20k. ft., Not much to choose from. This data is from Dean's "America's Hundred Thousand".

Below 20k ft., the P-47 was at a definite disadvantage against the German planes although it could typically outrun the Bf 109. It needed to stay high, dive on the enemy and climb back up and do it all again. Combat energy of the P-47 should have been superior due to high altitude and high airspeed unless wasted on dogfighting.

The P-47 definitely held the high ground above 25k ft. If you wanted to protect bombers at 20 and 25k, you definitely wanted the P-47. Now, if you could only get the range up. Of course there are those rumors about a new P-51 with that Merlin engine.

The F4U is a suburb aircraft and consistently showed it growth potential and to perform as it did as a carrier aircraft is admirable. The F4U-1 was not designed for this environment and while it would actually have worked in the long range high altitude escort mission, it was not optimized for it and the pilots would have suffered.

 

[renrich]

Dav, I think the Vmax figures for the P47 @ 5000 feet might be a little high. Should be more like 325-335 in military power but that is probably immaterial from a tactical POV. The F4U1D had the wing tanks deleted but could just have well have had them included. Someone else brought this up in another thread which I thought was a good idea. Take the F4U1A, delete the two outboard 50s and increase the size of the wing tanks so that the weight lost with the guns and ammo is gained back by the tanks and fuel. Then you have a fighter with even more than 361 gallons of internal fuel. Easily done and a good bit more range. Another minor point which is hard to prove but I doubt that the P47 ever had as good a roll rate as the F4U. To me, if the F4U1A had been available in numbers it would have made a lot of sense to use it as an escort fighter because of range until the P51B came along. The P47 would have definitely out performed it above 25000 feet but it still could have been effective. The FWs were not any great shakes above 20000 feet.

 

[glennasher]

Chuck Hawks thinks he knows stuff, I've read bunches of his firearms conclusions, enough to conclude he is often mistaken.................

 

[davparlr]

Dav, I think the Vmax figures for the P47 @ 5000 feet might be a little high. Should be more like 325-335 in military power but that is probably immaterial from a tactical POV.

I have many holes in my wall for butting it after trying to get stable data. Going back over my data sources on this is typically confusing. There are a couple of test reports that reflect the 350+ number and AHT chart also reflect this, my Wagner's "American Combat Planes" calls out 340 and some P-47D tests at 2000 hp reflect your number. There are several P-47 tests on propellers which I think are worthless.

The F4U1D had the wing tanks deleted but could just have well have had them included. Someone else brought this up in another thread which I thought was a good idea. Take the F4U1A, delete the two outboard 50s and increase the size of the wing tanks so that the weight lost with the guns and ammo is gained back by the tanks and fuel. Then you have a fighter with even more than 361 gallons of internal fuel. Easily done and a good bit more range.

I did an earlier quick study on comparison of escort potential for various aircraft including the F4U-1. The result was that the F4U-1 fuel remaining after six hundred mile ingress provided a very similar Normal Rated Power (NRP) operating time over the target as the P-51B. Extra fuel would be nice but I am not sure a necessity.


F4U-1
Internal Fuel, 351 gal
External Fuel, 175 gal
Transit Fuel, 600 miles, 186 gal
Return to Base, 600 miles, 186 gal
Fuel available at combat start, 340 gal (Note: internal fuel was required to be used for ingress after drop tank was empty.)
Fuel available for combat, 154 gal.
Combat time at NRP, 1 hour, 6 min.

P-51B
Internal Fuel 269 gal
External Fuel 216 gal
Transit Fuel, 600 miles 108 gal
Return to Base, 600 miles 108 gal
Fuel available at combat start 229 gal. Note: 85 gal fuselage tank used down to 65 gal for combat stability.
Fuel available for combat 121 gal
Combat time at NRP, 1 hr 14 min.

This was kind of a thumbnail study but should reflect reasonable comparisons unless there is an error.

Another minor point which is hard to prove but I doubt that the P47 ever had as good a roll rate as the F4U.

I was just looking at the chart in AHT

The FWs were not any great shakes above 20000 feet.

Some of the Fw 190A-5 performance capabilities were quite impressive but I do not know the time frame, maybe after 1943.

 

[timmy]

Dav, I think the Vmax figures for the P47 @ 5000 feet might be a little high. Should be more like 325-335 in military power but that is probably immaterial from a tactical POV. The F4U1D had the wing tanks deleted but could just have well have had them included. Someone else brought this up in another thread which I thought was a good idea. Take the F4U1A, delete the two outboard 50s and increase the size of the wing tanks so that the weight lost with the guns and ammo is gained back by the tanks and fuel. Then you have a fighter with even more than 361 gallons of internal fuel. Easily done and a good bit more range. Another minor point which is hard to prove but I doubt that the P47 ever had as good a roll rate as the F4U. To me, if the F4U1A had been available in numbers it would have made a lot of sense to use it as an escort fighter because of range until the P51B came along. The P47 would have definitely out performed it above 25000 feet but it still could have been effective. The FWs were not any great shakes above 20000 feet.

I'm just curious, does anyone on this forum have any information on what altitude Escort Fighters mostly saw combat in the ETO? I think I remember reading that B-17s flew around 25 000ft with a full load. The B-24 I think was under that, so am I correct in guessing its around 25 000ft ????

Just another question, what do most people think is the average altitude range in a dogfight. Like say for example the enemy meet at 25000ft,
would an average dogfight normally range from 20 000 to 30 000ft from that point ? All are each individual Dogfights just to viable even to make even a rough estimate on their combats altitudes range ??

 

[Shortround6]

Altitude for "Mostly saw combat" and mostly flew at before combat might not be the same thing. Some of the fighters would fly above the bombers to intercept the the Germans before they could dive down on the bombers. Most fighter to fighter combats usually descended in altitude if the fight went on for very long. No fighter of the time could sustain speed while executing maneuvers and the only way to keep speed up was to dive. Combats could end near the height they started or almost at ground level if the pursuit took long enough. Which ever side could start the fight with the higher altitude had an advantage which is why the fighters needed more altitude ability than the bombers.

 

[renrich]

Timmy, great question. I believe that most of us have an exaggerated idea of how high the bombers flew. Having looked at some mission stats it seems that the bombers flew a little higher as the war wore on probably as the flak became thicker. The flak killed more bombers than did fighters. The B24s could not fly as high as the B17s and weather and visibility had a lot to do with the altitude flown. At one point I believe that frostbite was disabling more aircrewmen than enemy action. I doubt that many if any bomber altitudes were at 30K feet. Also, the medium bombers flew at lower altitudes than the heavies. A guess from me would be that the average altitude flown in combat by the heavies would be around 24K feet. Some of the fighter escort would fly above the bombers but if they got too high they risked not being able to see the interceptors.

 

[tomo pauk]

[renrich:]The FWs were not any great shakes above 20000 feet.

Some of the Fw 190A-5 performance capabilities were quite impressive but I do not know the time frame, maybe after 1943.

There might be 3 'eras', to describe the performance of the Fw-190 with BMW 801D:
-March 1942 to Autumn 1942 - engine ratings are restricted, but the 190 is still perhaps the best performer among fighters
-Autumn 1942 to beginning of 1944 - restriction is lifted, the 190 is maybe the best all-around fighter, lacking only the combat range. Those are the A-4, A-5, A-6, A-7s.
-Spring 1944 - the heavy A-8 is int the units, the performance suffers, especially above 20000 ft, playing into (not only) USAAF hands.

MW-50 sets for the 190s are helpful only under 20 - 22 kft.

David's figures list the performance of the A-5 (non-restricted, really a great fighter.

 

[timmy]

Altitude for "Mostly saw combat" and mostly flew at before combat might not be the same thing. Some of the fighters would fly above the bombers to intercept the the Germans before they could dive down on the bombers. Most fighter to fighter combats usually descended in altitude if the fight went on for very long. No fighter of the time could sustain speed while executing maneuvers and the only way to keep speed up was to dive. Combats could end near the height they started or almost at ground level if the pursuit took long enough. Which ever side could start the fight with the higher altitude had an advantage which is why the fighters needed more altitude ability than the bombers.

Timmy, great question. I believe that most of us have an exaggerated idea of how high the bombers flew. Having looked at some mission stats it seems that the bombers flew a little higher as the war wore on probably as the flak became thicker. The flak killed more bombers than did fighters. The B24s could not fly as high as the B17s and weather and visibility had a lot to do with the altitude flown. At one point I believe that frostbite was disabling more aircrewmen than enemy action. I doubt that many if any bomber altitudes were at 30K feet. Also, the medium bombers flew at lower altitudes than the heavies. A guess from me would be that the average altitude flown in combat by the heavies would be around 24K feet. Some of the fighter escort would fly above the bombers but if they got too high they risked not being able to see the interceptors.

Good information, thanks for the replies guys

 

[renrich]

The best reference I have on the FW190 is a lengthy article in "The Great Book of WW2 Airplanes." It is quite detailed and because of the German tendency to get over complicated the reader can get confused about all the different Mks. and models. To me, what is quite interesting is that the FW190 design began in 1937 and the gestation of the airplane was somewhat similar to that of the F4U but always about a year ahead. The Corsair design was begun in 1938. The design of the two AC was determined based on two radial powerplants by BMW and P&W which were under development at the same time the AC were being developed. Engine problems were many for both AC with the loss of quite a few early models because of engine failure. The FW also had overheating problems in the early models. One of the early prototype FWs attained a top speed of 369 mph in level flight in 1939. The Corsair protoype got 405 mph in 1940. As the AC designs evolved the performance numbers for the two were similar except that the FW always climbed better and the F4U always had more range. The FW became more heavily armed and the Corsair, of course, had to be a ship board AC. The radial engined FW lost much of it's performance above 15000-20000 feet and the engine was changed out to a liquid cooled in order to cope with the high flying heavy bombers. That was the D models.

To me, having had a lot of experience with a lot of cars, American, German and Japanese. The motto of American car builders seems to be "keep it simple stupid" while the German's is "keep it complicated smarty" and that seems to have been the tendency of the WW2 AC designers also. (editorial on my part and just an opinion)

 

[drgondog]

Timmy, great question. I believe that most of us have an exaggerated idea of how high the bombers flew. Having looked at some mission stats it seems that the bombers flew a little higher as the war wore on probably as the flak became thicker. The flak killed more bombers than did fighters. The B24s could not fly as high as the B17s and weather and visibility had a lot to do with the altitude flown. At one point I believe that frostbite was disabling more aircrewmen than enemy action. I doubt that many if any bomber altitudes were at 30K feet. Also, the medium bombers flew at lower altitudes than the heavies. A guess from me would be that the average altitude flown in combat by the heavies would be around 24K feet. Some of the fighter escort would fly above the bombers but if they got too high they risked not being able to see the interceptors.

Ren- In the ETO, particularly as weather worsened and cloud cover frequently 10/10 the bombers flew significantly lower in 1945. I just looked through R/V altitudes and Mission summaries for Jan-March 1945. There were many B-24 strikes at ~ 18.000-20K feet as well as B-17 strikes in the 22-23,000 foot range.

I can't find any particular written observations regarding the "why' - just the data. Also notably the German flak gunners started targeting H2X radars for fusing and tracking info in the summer of 1944, which required countermeasures to reduce effectiveness. The 10/10 cover affected both bombing accuracy and flak accuracy, despite lower altitude runs.

 

[JoeB]

I did an earlier quick study on comparison of escort potential for various aircraft including the F4U-1. The result was that the F4U-1 fuel remaining after six hundred mile ingress provided a very similar Normal Rated Power (NRP) operating time over the target as the P-51B. Extra fuel would be nice but I am not sure a necessity.


F4U-1
Internal Fuel, 351 gal
External Fuel, 175 gal
Transit Fuel, 600 miles, 186 gal
Return to Base, 600 miles, 186 gal
Fuel available at combat start, 340 gal (Note: internal fuel was required to be used for ingress after drop tank was empty.)
Fuel available for combat, 154 gal.
Combat time at NRP, 1 hour, 6 min.

P-51B
Internal Fuel 269 gal
External Fuel 216 gal
Transit Fuel, 600 miles 108 gal
Return to Base, 600 miles 108 gal
Fuel available at combat start 229 gal. Note: 85 gal fuselage tank used down to 65 gal for combat stability.
Fuel available for combat 121 gal
Combat time at NRP, 1 hr 14 min.

The important assumption you make about fuel quantities is that the F4U-1 will enter combat with fuel in the unprotected internal wing tanks. The standard USN assumption was that it would not. Therefore in the 'A/c Characteristics and Performance' sheet for F4U-1 dated March 1 1944, the official radius is the same whether the internal wing tanks are used or not, 340 statute miles (they list capacities of 237 main internal protected tank, 175 gal drop, and optional condition adding 2*62 unprotected internal, total 536, a little different from what you said but same general idea I assume). In the unprotected tanks case, the a/c was assumed to drop 166 gal in the drop tank if entering combat immediately 340 miles out, or else would have a 186 min CAP endurance. Not using the wing tanks, it would drop 48 gals in the drop tank or be able to patrol for 54 minutes at the 340 mile radius.

The 340 would still not be apples and apples to your estimate because it includes conservative deductions for warm up, take off, marhalling and climb which you haven't included, but in any cases those assumptions could be relaxed for a land based a/c. But, sticking to the assumption of no unprotected internal fuel in combat, the F4U's radius was still not 600 statute miles, and no actual operation I know of contradicts this. Whereas, the P-51's practical combat radius really was over 600 miles as shown by actual operations by P-51D/K's in the Pacific. OTOH the F4U could have been further modified to achived greater range, as was the P-51 (as in 85 gal tank, not originally installed in very early series B's).

Joe

 

[renrich]

Another coincidence about the development of the FW190 and F4U was accidents with the prototype. The FW had several prototypes and one had a bad accident. The AC was rebuilt using the planned for larger wing and tail surfaces. The Corsair prototype had a bad accident and was rebuilt like the original. An interesting what if to me is what if the original design of the Corsair was taken and a model built strictly for land based use. With no wing fold, no tail hook and with the structure stressed for landing on air fields instead of carrier decks and with no salt water protection, there must have been some significant weight loss. In addition a different air foil may have meant less drag but longer takeoff and landing distances along with a higher stall speed but better Vmax, climb and acceleration. Also Dean in AHT speculates that the right wing spoiler may have adversely effected the Corsair's turn rate. That spoiler would have been probably left off the land version. I am no engineer but if a thousand pounds were saved along with a less draggy air foil a very high performance AC could have resulted.

 

[Shortround6]

An interesting what if to me is what if the original design of the Corsair was taken and a model built strictly for land based use. With no wing fold, no tail hook and with the structure stressed for landing on air fields instead of carrier decks and with no salt water protection, there must have been some significant weight loss.

Some of the Goodyear production did not have folding wings or or tail hooks. So far little or no difference in performance has come to light. It may be there, just the documents haven't been dug out yet?

In addition a different air foil may have meant less drag but longer takeoff and landing distances along with a higher stall speed but better Vmax, climb and acceleration.

Now you have a new wing that needs flight testing and may or may not be able to be built using existing tooling, jigs, fixtures. Some will have to change but how much?

I am no engineer but if a thousand pounds were saved along with a less draggy air foil a very high performance AC could have resulted.

You are quite likely correct, the question is WHEN such an aircraft could have shown up? How many weeks to design the new wing, how many weeks to build the prototype, how many weeks to test fly it, how many weeks to design and build the new jigs and fixtures. The First F4U-1D isn't accepted by the Navy until April 22 1944.

 

[renrich]

I think what I am speculating about is, if in 1940 when the XF4U flew at 400 plus mph, a different manufacturer had taken the blueprints and tweaked the design . I don't think the FGs with no tail hook and wing fold gained a lot of performance but it must have meant a few hundred ponds less. A few hundred pounds on an F4F or F2A was a big deal but not on a Corsair. As I say, I am no engineer except for two years in college and then realised I was not cut out for that and became a geology major but it seems as if an air plane stressed for deck landings would have to weigh somewhat more than the same AC stressed only for landing on air fields. Eastern built a lot of FMs and TBMs after Grumman designed them and several other manufacturers built AC designed by others. Could be a pie in the sky.

 

[davparlr]

Okay, here is an estimate for a F4U-1 built to AAF requirements using the F-86F/FJ-2 similarities. Effectively, the FJ-2 was navalized F-86F with four cannon instead of six guns, which were roughly the same weight total. The empty weight of an F-86F is 10,815 lbs and the FJ-2 is 11,802 lbs or 92% less. So, a one-to-one comparison to the F4U-1, at an empty weight of 8982 an AAF designed F4U would be 8231 or 750 lbs lighter. However, the FJ-2 lands much faster than the F4U-1 and therefore probably has more structure and gear modifications than the F4U-1. So let's guesstimate a 500 lb savings. This would have improved climb by 2-300 ft/min. This weight is close to the Fw-190A empty weight, and reducing the wing area 30% to roughly the area of the Fw, there is reason to believe its performance would be equivalent to the A-5. However, where would you put the fuel?

 

[davparlr]

The important assumption you make about fuel quantities is that the F4U-1 will enter combat with fuel in the unprotected internal wing tanks. The standard USN assumption was that it would not. Therefore in the 'A/c Characteristics and Performance' sheet for F4U-1 dated March 1 1944, the official radius is the same whether the internal wing tanks are used or not, 340 statute miles (they list capacities of 237 main internal protected tank, 175 gal drop, and optional condition adding 2*62 unprotected internal, total 536, a little different from what you said but same general idea I assume).

"Americas Hundred Thousand" list wing tanks holding 57 gallons. I would guess the performance sheet is correct if it is from the Navy.

In the unprotected tanks case,

Originally the wing tanks were protected by a CO2 system. I am not sure of the effectiveness of this system but my assumption was that it was. There was apparently room for wing tanks that may possibly have been protected, with less fuel.

the a/c was assumed to drop 166 gal in the drop tank if entering combat immediately 340 miles out, or else would have a 186 min CAP endurance. Not using the wing tanks, it would drop 48 gals in the drop tank or be able to patrol for 54 minutes at the 340 mile radius.

My assumption was that the drop tanks would not be released until contact with the enemy air, in this case over the target area. As long as the assumption is applied across the board, data is usable. In the F4U case I did assume wing tank were combat usable, or could be made that way. Contact with enemy air anywhere prior to target area obviously would affect performance, but again, if applied equally to subject candidates, impact would also be similar.

The 340 would still not be apples and apples to your estimate because it includes conservative deductions for warm up, take off, marhalling and climb which you haven't included, but in any cases those assumptions could be relaxed for a land based a/c.

My assumption was that each candidate would be required to obtain similar departure and recovery requirements thus cancelling the affect. I realize that F4U would probably utilize more fuel in this effort than say the P-51, but I was too lazy to calculate it and suspect the difference is rather a small % of overall effort. I could be off a bit.

But, sticking to the assumption of no unprotected internal fuel in combat

Not necessarily reasonable since this would be an AAF aircraft modified to support long range escort duty.

The purpose of this quick study was not to generate a detailed fuel usage report mainly due to my concern about the lack of available data, but to just provide a thumb nail comparison for a clearer picture of the candidates escort capabilities.

 

[drgondog]

Okay, here is an estimate for a F4U-1 built to AAF requirements using the F-86F/FJ-2 similarities. Effectively, the FJ-2 was navalized F-86F with four cannon instead of six guns, which were roughly the same weight total. The empty weight of an F-86F is 10,815 lbs and the FJ-2 is 11,802 lbs or 92% less. So, a one-to-one comparison to the F4U-1, at an empty weight of 8982 an AAF designed F4U would be 8231 or 750 lbs lighter. However, the FJ-2 lands much faster than the F4U-1 and therefore probably has more structure and gear modifications than the F4U-1. So let's guesstimate a 500 lb savings. This would have improved climb by 2-300 ft/min. This weight is close to the Fw-190A empty weight, and reducing the wing area 30% to roughly the area of the Fw, there is reason to believe its performance would be equivalent to the A-5. However, where would you put the fuel?

Dave - I wouldn't count on proportionality comparisons. Speculatively I would think the combination of spar strengthening, arresting gear and wing fold structure delta between FJ-2/F-86 would not be far off in gross delta between F4U Navy and F4U AAF. I would expect 700-900 pound difference with the highest percentage in the arresting gear and wing fold structures - IF the F4U AAF was designed as a land based fighter from the beginning. As a 'retrofit' with new wing/gear only and simply remove arresting hook - your figure seems reasonable.