P-47N Thunderbolt vs. F4U-4 Corsair - Which was superior?

[DAVIDICUS]

I was at the Evergreen Aviation Museum (home to the Spruce Goose) earlier this week. They have some WWII combat aircraft sitting together on the east side of the museum including a Hellcat, Corsair, Spitfire, Bf-109, B-17, P-51, P-38, A-26 and Avenger. Because I was there during the week it wasn't very busy. The docents outnumbered the patrons. One of the docents approached me as I stood between the Hellcat and Corsair and began telling me the kill statistics for the Hellcat and I raised the subject of the Naval Air Combat Statistics' tentative conclusion that the F6F was slightly superior to the F4U in combat, apparently chiefly because of its greater ability to survive damage.

A few minutes into listening to my summary of the data, he asked if I could stay there for a minute while he retrieved one of the other docents who flew Corsairs in Korea. A couple of minutes later, he returned with another docent, Rob, who flew Corsairs off of a carrier in combat. The other docent introduced Rob into the conversation by reiterated some of what I had said about the striking vulnerability of the Corsair and Rob just looked at me and nodded his head.

He wasn't familiar with the striking disparity between the Hellcat and Corsair revealed by the Navy's combat statistics but said he wasn't surprised. He said that the vulnerability of the Corsair's oil cooler was well known and was a source of anger on the part of pilots who thought a redesign would make them safer. He said it was always on their mind and that sometimes "you wouldn't get too low" in your attack due to that specific concern. He also said that Skyraider pilots did not have the same concern.

It's a great museum, although extremely expensive! There is a separate space museum there too and the cost for myself and six year old son to go through the aviation museum, space museum and to see an IMAX film was ... brace yourself ... $60.00.

 

[renrich]

I still wonder about how big the infamous oil cooler in the Corsair was and what was the probability of it being hit and if that was such a universally known weak point why the oil cooler in the Hawker Sea Fury was located similarly. The fact still remains that the Corsair delivered many more tons of bombs then did the Hellcat in WW2 and had less losses to triple A. The fact is that the Corsair did yeoman duty in Korea and was quite effective.

 

[DAVIDICUS]

I don't think it's surprising that lessons learned only well into 1946 would not have guided aircraft design years earlier. The Naval Air Combat Statistics wasn't published until mid 1946 and it did not mention the oil cooler as culprit. And I frankly don't know that the Sea Fury did not have some remedial armor plate or deflection apparatus installed to address this as the later AU-1 Corsair did.

The probability of the oil cooling system being hit was certainly greater than with the Hellcat as it is spread over a larger area. There was also the related issue of the pilot's oil pressure gauge not registering a loss of pressure until almost all the oil had left the system. The Corsair operating manual states that the pilot should check the trailing edges of the wings frequently in combat for that reason. The manual for the Hellcat has no such caveat. Similarly, the manual for the Thunderbolt, which shares the same oil cooling design as the Hellcat, makes no mention of this either.

The fact that the Corsair dropped more bombs than the Hellcat in WWII has no relevance to the Corsair's relative vulnerability realized in 1946.

The fact that fewer Corsair's were lost in AA fire than Hellcat's under circumstances that are not apples to apples makes any conclusions about the two aircraft relative to vulnerability to AA damage merely speculative.

Now, if you had, say, data for 22,000 sorties for the Hellcat and Corsair for the same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations" where the two aircraft received "about the same number of hits per sortie" from AA fire, I think you would have an overwhelming mountain of evidence from which to base concrete conclusions regarding comparative vulnerability to AA fire.

And I'm sure that if such a mountain of apples to apples data showed that the Hellcat was 58% more likely not to return after suffering AA fire than the Corsair, that you would agree that the Corsair is an even awesomer plane than was previously thought.

 

[renrich]

I don't know about it being awesomer although that sounds like an awesome word but it seems unreasonable to me that if the oil cooler was as big a problem for the Corsair as portrayed by statiticians, pilots would have been screaming to high heaven from early 1943 on as in, when a pilot was picked up out of the drink he would say, " It was that dratted, dad gum oil cooler again and why does not Vought do something about it?" An example is that a pilot was lost because he accidently while in combat used the CO2 blow down bottle for the landing gear instead of the CO2 bottle for purging the wing fuel tanks. They were located side by side and after a chew out for Boone Guyton, chief test pilot for the Corsair, by an admiral, Vought changed the location for the bottles.That was not as big a modification as relocating or armoring the oil cooler but if that was an extreme vulnerability it would have been fixed IMO. Also to say that the extreme difference between Hellcat losses to AAA and Corsair losses to AAA is not a valid point because they did not happen side by side seems unreasonable to me. No reflection on anyone here on this forum but the old adage, " there are lies, damn lies and statistics," comes to mind here. If old guys at an air museum were very conscious of the oil cooler problem on Corsairs in Korea, one wonders why WW2 pilots did not raise the issue continually. Incidently, Boone Guyton never mentions any oil cooler issues in his book, "Whistling Death."

 

[DAVIDICUS]

Renrich, see posts #318, #319 and of course, #320.

No reflection on anyone here on this forum but the old adage, " there are lies, damn lies and statistics," comes to mind here.

The thing about that old adage is that the data always reveals the lies, damn lies and statistics. Like when we are told that women only earn .74 cents for every dollar that a man earns which is then twisted into some sort of apples to apples comparison between men and women, job for job, by those with a radical feminist agenda. Turns out that they just take all the money earned by women and divide by the number of women and then all the money earned by men and divide by the number of men. Looking at the data in the study reveals this. Turns out that when you control for variables that govern pay in a specific position, women's pay is closer to .97 for every $1.00 that a man earns.

This is why controlling for variables is so important. Here we have data for 22,000 sorties for the Hellcat and Corsair for the same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations" where the two aircraft received "about the same number of hits per sortie" from AA fire. A more well controlled study you won't find and could not ask for. As I said in post #366, "We have more controlled data to support the enormous disparity in vulnerability between the Corsair and Hellcat than to support any disparity existing at all between the Mustang and Thunderbolt."

When you say that for the whole of WWII there were fewer Corsairs lost to AA fire than Hellcats and try to pass that off as evidence on the issue of vulnerability of the Corsair relative to the Hellcat, lies, damn lies and statistics does indeed come to mind. In your own post #365, you said, "I don't believe that the statistical study is valid because there are too many variables." So now we are adopting stats for the whole war with no controlling for variables at all as long as we can get to a number we want?

Incidently, Boone Guyton never mentions any oil cooler issues in his book, "Whistling Death."

And for a littany of sources that do reference the oil cooler issue, see post #333 and #362. Obviously an oil cooler hit can bring down any plane and incidentally, I have never come across any source that singles out the oil cooler as a special Achilles heel for the Hellcat or Thunderbolt which share a different design/ layout.

 

[renrich]

Maybe a typo in your post but in WW2, the Corsair dropped more than twice the tonnage of munitions than the Hellcat and had only 349 losses to AAA compared to 553 losses to AAA for the Hellcat. I am not saying that the Hellcat was more vulnerable to AAA and not saying that the Corsair was not more vulnerable but one could take the fact that the Hellcat suffered 553 losses while dropping 6503 tons of bombs and the Corsair dropped 15621 tons of bombs while suffering 349 AAA losses and come up with a nice argument that the Hellcat was a lot more dangerous to bomb in than the Corsair. To me that argument doesn't hold water because of the variables. If the oil cooler armoring or relocating had not been desirable, they would not have done it on the AU and F4U7. I just don't believe it was the deficiency you and some others make it out to be. The Corsair was used as a dive bomber more than the Hellcat because it was better in that role, almost as accurate as a Dauntless. Maybe that accounts for the apparent excessive vulnerability in comparable missions. I don't know about you but a bird coming straight at me is easier to hit than a passing shot. As far as data in comparable missions is concerned, I am amused at how accurate you think it is. How do they know how many hits a downed aircraft took and where the hits occured. Did they go dig up the wreckage on every downed Hellcat or Corsair. I call BS on that. I know a pilot who flew missions in Korea in the AD and Corsair. He never mentioned worrying about his oil cooler but that proves nothing. If you read Guyton's book he describes many problems with the Corsair but never mentions the oil cooler. That proves nothing either. The only thing we know for a fact is that the Corsair flew lots more air to ground missions and had less losses to AA. We also know that in comparable missions which the Navy kept records on the Hellcat had less losses and that the number of hits and their location seems to indicate the oil cooler was a vulnerability for the Corsair. As to how big that vulnerability was I say we can't be sure because I am absolutely certain that the Navy does not know how many hits each airplane took and where they were located.

 

[DAVIDICUS]

I am not saying that the Hellcat was more vulnerable to AAA and not saying that the Corsair was not more vulnerable but one could take the fact that the Hellcat suffered 553 losses while dropping 6503 tons of bombs and the Corsair dropped 15621 tons of bombs while suffering 349 AAA losses and come up with a nice argument that the Hellcat was a lot more dangerous to bomb in than the Corsair.

Yes, lies, damn lies and statistics do make nice arguments. To quote you, "I don't believe that the statistical study is valid because there are too many variables." You talk the talk but don't seem to want to walk the walk.

As far as data in comparable missions is concerned, I am amused at how accurate you think it is. How do they know how many hits a downed aircraft took and where the hits occurred. Did they go dig up the wreckage on every downed Hellcat or Corsair. I call BS on that.

The huge number of events (sorties) and the Navy's own declaration of same time period, flying from the same ships on missions under the "same conditions" in "comparable operations" speaks both definitively and authoritatively. Did I ever say that the Naval Air Combat Statistics made any representations whatsoever as to how many hits or placement of hits? Again, from my post #403:

"The Naval Air Combat Statistics wasn't published until mid 1946 and it did not mention the oil cooler as culprit."

It also does not mention number of hits on planes suffering damage or locations of hits on planes suffering damage. The study controlled just for planes actually suffering AA damage. The enormous number of sorties and well controlled same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations" where the two aircraft received "about the same number of hits per sortie" is what makes the study and its conclusions valid.

"I don't know about you but a bird coming straight at me is easier to hit than a passing shot."

Good point. So if these dive bombing missions only undertaken by the Corsair were causing more AA losses as a result of it being easier to hit the Corsairs, wouldn't that make for significantly more hits on Corsairs? How do we reconcile that with the fact that the Corsairs and Hellcats took "about the same number of hits per sortie" which one would expect and serves as further validation when we are looking at the same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations".

Do you really think that using Corsairs for some dive bombing is what is causing the more than 22,000 sorties for the same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations" where the two aircraft received "about the same number of hits per sortie" to reflect a 58% greater chance of not returning after actually suffering AA damage? Would we really be having this discussion if the data had went to other way - against the Hellcat?

As to how big that vulnerability was I say we can't be sure because I am absolutely certain that the Navy does not know how many hits each airplane took and where they were located.

You are right. All the Navy knows is that in looking at more than 22,000 sorties for the same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations" where the two aircraft received "about the same number of hits per sortie", the Corsair was 58% less likely to return. ... Oh, and they addressed an oil cooler vulnerability issue on the AU-1.

"I just don't believe it was the deficiency you and some others make it out to be."

You almost make it seem as though "some others" and myself are in the minority. This issue has been vetted for quite a while now across this and other threads and you, my friend, are the only person who has stepped forward with disbelief to challenge the NACS. I would add that it is plain to everyone (and everyone has followed this issue) that your disbelief is not grounded in any inability to grasp the data. As I have pointed out several times, had the data gone the other way, you would be the NACS's chief proponent on the issue of Hellcat vs. Corsair relative vulnerability to AA.

 

[renrich]

If you bothered to read my earlier posts, I mentioned that the oil cooler problem caused a fix to be undertaken in the AU and the F4U7.
Another point is that 22000 sorties sounds like a lot of sorties. Were the number of sorties divided equally between the two types? I would guess that the number of sorties flown by Hellcats was greater than those flown by Corsairs. Did they identify which sorties were flown by which types in a dive bombing mode or a glide bombing mode? Since only 349 Corsairs were lost to AAA in the whole war out of around 11500 built it does not sound as if the percentage of Corsairs lost in the 11000 or so sorties is very high.

 

[DAVIDICUS]

If you bothered to read my earlier posts, I mentioned that the oil cooler problem caused a fix to be undertaken in the AU and the F4U7.

Yes, well I also read your earlier comment (Post #365) that "I don't believe that the statistical study is valid because there are too many variables" after which you then decided to adopt stats for the entire war without any attempt to control for anything. This sort of boggles the mind. You want to ditch the Naval Air Combat Statistics controlled data for the same time period, flying from the same ships and flying missions under the "same conditions" in "comparable operations" where the two aircraft received "about the same number of hits per sortie" because there are too many uncontrolled variables and instead adopt the entire war without any attempt to control any variables whatsoever?

Do I really need to respond to that?

Why would the number of sorties need to be divided equally between the two aircraft? ??? The data set for the Corsair was 6,000! Again, if the differential in population size was skewing results, then we wouldn't see "about the same number of hits per sortie" under circumstances where we have the same time period, operating off the same ships, where missions were under the "same conditions" in "comparable operations." That's really the inescapable glue that holds this analysis together (the two aircraft received "about the same number of hits per sortie") and in the end, when the well controlled data is out on the table, no amount of lies, damn lies and statistical manipulation can alter the facts and necessary conclusions that flow from those facts.

When you hear of a study that shows that even when lifestyle and diet are controlled for, blacks have a lower life expectancy than whites, do you similarly reject such a finding because the population of blacks is less than 1/5 of the white population? Does the difference in population size pose an insurmountable obstacle to the drawing of valid conclusions?

I do not see a break down of dive bombing mode or glide bombing mode and still don't see the relevance. You yourself just argued that the Corsairs would have been easier targets to hit utilizing dive bombing tactics which only they would have employed right? ("Maybe that accounts for the apparent excessive vulnerability in comparable missions. I don't know about you but a bird coming straight at me is easier to hit than a passing shot.") You were apparently trying to account for the reason why fewer Corsairs returned to their ships. You forgot, however, that the two aircraft received "about the same number of hits per sortie" which really just confirms that the missions and conditions under which they were flying were the same thus undercutting your argument. What am I missing?

 

[DAVIDICUS]

On the subject of taking AA fire and making it back -- WOW.

(Photo from a post by BC1 on another thread.)

 

[Duke Soddy]

I'm curious which of these were better in the air to air role and why.

This is such a tough one, I like both of the aircraft. Objectively they both have reputations as rugged and durable aircraft, but the jug edges out the corsair in that arena. The Corsair would edge the Jug out in wing loading and everywhere else except in range. Give any combination of variables in a combat scenario for the two to perform in, you could honestly say in WWII either one of these planes would have and did perform the air to air combat role well.

P-47, for its survivability. If I were a pilot to choose, I want the one with the reputation to bring me home.

 

[Duke Soddy]

What your missing is ... Figures don't lie, but liars do figure.

 

[Soren]

The F4U was overall the superior fighter, there's no doubt about that, it was more maneuverable and faster than the P-47. It was only at high altitudes that the P-47 was better. Both were great a/c though.

 

[Clay_Allison]

Dogfighting on the deck: F4U
Flying top cover/bomber escort: P-47
Strafing Ground Targets: P-47
Attacking enemy airfields: F4U
Fighting Japanese: F4U
Fighting Germans: P-47
Dropping Bombs/Attacking Ships: F4U

 

[keystonekid60]

Amen to that,what an aircraft was designed to do and what it actually ended up doing in combat are two totally different things. Also about the jug versus bent-wing,the F-4 eventually got 4 "count em 4 20 mm canons,now that's firepower in my book!

 

[davparlr]

These two powerful aircraft are closing out the era of propeller driven fighters. Both are advanced designs of successful aircraft and both are powered by the R-2800 eng. Both have a justified reputation of being rugged aircraft. The main difference is that the F4U-4 is an engine driven supercharged aircraft designed for carrier use, the P-47N is a turbo-charged engine designed for high altitude escort and long range interdiction.

Comparing the performance of these two aircraft with equal fuel and weapons load results in the following stats.

At SL, the P-47N with 2600 hp available, out powers the F4U-4 at 2450 hp, but gives up around 1600 lbs in weight. As a result, the F4U has better power to weight and wing loading than the P-47, even with larger wings, and is slightly faster. Both climb well being in the 4000 ft/min range, but the F4U still has an advantage.

At 10k, things begin to change. The P-47's engine now develops 2800 hp, a value it will hold to about 33k ft. The F4U engine is generating about 2000 hp at this altitude. The P-47 is pulling about 5 lb/hp and the F4U has about 6.2 lbs/hp. The P-47 will have better acceleration and reducing climb disadvantage. Climb should still be in the F4Us favor and has a good amount of airspeed advantage.

At 20k, the situation is roughly the same. F4U hp has dropped 100 hp, so the P-47N has 900 hp more than the F4U. The F4U still has an airspeed advantage over the P-47.

Above 20k, the P-47, with over 50% more power available, starts to get into it strength, increasing in speed. Above 25k, very few, if any, aircraft is going to stay with it, at least up through 35k.

My conclusion, the F4U-4 will have an advantage below 20k, but suffers a bit in power loading. From 20k to 25k, pretty equal, above 25k the P-47N is the plane to have.

 

[renrich]

Dav, very good summation, IMO. Also, IMO, the F4U4 has overall. three big advantages over the P47. They are:
The F4U4 can equally operate from a carrier deck and a very short land base. The P47N cannot.
The F4U4 has a maneuverability advantage over the P47N, especially below 25000 feet.
The F4U4's advantages are below 25000 feet where almost all ACM in WW2 takes place.

 

[Colin1]

Good summary Dav

each plane was tailored well for the service/arm for which it was designed

 

[windswords]

"The F4U4 can equally operate from a carrier deck and a very short land base. The P47N cannot.
The F4U4 has a maneuverability advantage over the P47N, especially below 25000 feet.
The F4U4's advantages are below 25000 feet where almost all ACM in WW2 takes place."

The Bolt would have carrier capability too if they outfitted it with arrestor gear and strengthened landing gear- and if they could find a carrier with a big enough landing deck! So I don't think it matters here. Besides, the Bolt has a thousand mile greater range.

Now about maneuverability below 25K feet. In Europe the Bolt faced planes that were more maneuverable - the Me-109 and FW-190 - and blew them out of the sky. Most of that combat took place below 25000 ft, especially later in the war when the Bolts were relegated to low level ground attack. If they faced enemy fighter opposition down on the deck they had to fend for themselves. There were no Mustangs flying top cover for them. In the Pacific practically every Japanese fighter they faced were more maneuverable than the Bolts. I don't remember combat pilots complaining that their mounts were not maneuverable enough against the Japanese.

Most of us agree that the maneuver vs.energy fighter debate was was won by the energy fighter. Why are we all of a sudden giving so much credence to the Corsairs greater maneuverability? Of more importance should be speed, armor, armament, and overall toughness. Not to mention the greater roll rate and dive speed of the Bolt. So yes the Corsair has some advantages but the advantages of the Bolt are more important when it comes to air to air combat - as it was practiced in WWII, not as it's played in modern combat simulation games.

 

[drgondog]

The Bolt would have carrier capability too if they outfitted it with arrestor gear and strengthened landing gear- and if they could find a carrier with a big enough landing deck! So I don't think it matters here. Besides, the Bolt has a thousand mile greater range.

There has never been a vessel long enough to launch a P-47 of any variety with a full load of fuel to take advantage of the range differential - so that would be a spurious argument.

Now about maneuverability below 25K feet. In Europe the Bolt faced planes that were more maneuverable - the Me-109 and FW-190 - and blew them out of the sky.

Of significant importance is that the P-47C and D below -25 simply didn't engage many Fw 190s and me 109s re: Mustang because they didn't have the range and the M was a nightmare reliability wise for the 56th FG. True the 9th AF did engage and engage near the deck. I don't have the numbers but would speculate that their air to air ratio was no better than half of their brthren in the 8th AF - which started most of their fights at altitude and was able to trade altitude for speed - unlike the low level Jugs.

Even the 8th AF jugs were far below the air to air ratio of the Mustang over Europe.

Most of that combat took place below 25000 ft, especially later in the war when the Bolts were relegated to low level ground attack. If they faced enemy fighter opposition down on the deck they had to fend for themselves. There were no Mustangs flying top cover for them. In the Pacific practically every Japanese fighter they faced were more maneuverable than the Bolts. I don't remember combat pilots complaining that their mounts were not maneuverable enough against the Japanese.

Simply because the survivors of air combat did not engage in the Japanese fighter strike zone - and the ones in Europe against a pilot of equal skill in an Fw 190 or Me 109 below 15,000 feet was in deep trouble also given no tactical advantage in the encounter. The Jug was out rolled by the Fw 190 below 350mph and the Fw 190 was about as fast - the 109 out climbed (by far) and out turned below 25,000 feet.

By the time the 9th AF was heavily engaged in low level support - May/June 1944 - much of the LW experienced pilots were lost - so the skill factor of the opposition was very spotty.

Most of us agree that the maneuver vs.energy fighter debate was was won by the energy fighter. Why are we all of a sudden giving so much credence to the Corsairs greater maneuverability? Of more importance should be speed, armor, armament, and overall toughness. Not to mention the greater roll rate and dive speed of the Bolt. So yes the Corsair has some advantages but the advantages of the Bolt are more important when it comes to air to air combat - as it was practiced in WWII, not as it's played in modern combat simulation games.

Debatable - that is why there are contrary opinions to your own

As earlier posters commented the discussion is about F4U-4 and -5s against the best of the P-47s - the N.

I believe Dave summed up the performance distinctions quite well. The air to air combat ratio in the Pacific is heavily weighted against the earlier P-47D Jug in comparison, but the Corsair didn't fight as consistently tough/skilled Japanese pilots until the end of the war. I haven't seen the data but it would be interesting to compare for the Okinawa and Korea fights between the two ships but that data is nowhere as comprehensive as ETO.