Most Overrated aircraft of WWII.....?

[renrich]

As you know there are all kinds of performance figures floating around on all a/c from ww2. My numbers I quoted were from a graph based on the MFR and the USAAF. I doubt very much that the P51D on average could touch 375 mph at sea level or 430 mph at 30000 ft. My graph shows it at about 417 mph at 30000ft. The Vmax for the P47D 23,26 at 30000 ft combat power was about 435mph TAS which was the same as at 25000ft. So the P47 had a slight edge in speed at altitudes above 25000 ft which is why the joint fighter conference rated the P47 as best fighter above 25000 feet. More food for thought. But I still think that us arm chair experts have a false impression of ww2 ACM in that we think it was all about high speed and high altitudes. Combat power was only good for a few minutes. If one flew around very long with the throttle firewalled one probably did not have an engine to go home. At 30000 ft or more the pilot was doing his best just not to stall and fall out of the sky and was not worried overmuch about tight turns or rolls not to mention freezing to death especially in winter over Europe. And the fact is that most air to air kills took place when the killee had no idea the killer was on his six until it was all over. One major factor in ACM in Europe was that few pilots had the skill to be effective at deflection shooting. Thus most kills took place from the 6 o clock position.

 

[pbfoot]

. But I still think that us arm chair experts have a false impression of ww2 ACM in that we think it was all about high speed and high altitudes. Combat power was only good for a few minutes. If one flew around very long with the throttle firewalled one probably did not have an engine to go home. At 30000 ft or more the pilot was doing his best just not to stall and fall out of the sky and was not worried overmuch about tight turns or rolls not to mention freezing to death especially in winter over Europe. .

Amen just read an anecdote of guy hurrying home from another base in a P47 and he was quite impressed at cruising at 300 knots . The Mosquito cruised at 240 and the Hurricane at about 160. Even the C47s I flight planned cruised at 140 no where near top speeds

 

[drgondog]

One major factor in ACM in Europe was that few pilots had the skill to be effective at deflection shooting. Thus most kills took place from the 6 o clock position.[/QUOTE]

True enough until the K-14 arrived in July-Aug 1944, and G suits in November 1944. The game changed considerably

Believe what you will on the performance of the 47 - I can't comment from personal experience but I do have 56.5 hours in a 51D&H (which actually is 54 hours more than my father had when he flew his first combat mission in one)

I have yet to talk with one fighter pilot in the 354th FG, which was the Pioneer Mustang Group, that a.) loved the 47 when they had to fly it for 4 months 11/44-2/45, and b.) weren't delighted when they got their beloved 51's back in March 1945. They would tell you to a man that they felt safer on the deck from flak in a 47 but not against a German fighter.

Right or wrong there was a reason the USAAF and USAF standardized on the 51 after WWII - and it wasn't because they wanted the second best piston fighter available to them. Ditto F4u-4/5 for the Navy

Regards,

Bill

 

[lesofprimus]

Money money money..... Ease of training ease of training..... 51's were cheaper and easier for some flight school noob to fly.... Then theres the whole escort range gimmick...

 

[drgondog]

Nice try - There were more than a few of the old hands that remember training for WWII in B-10's and P-35's and Brewster Buffalo's (for our jarhead friends) and the losses we took with P-39s that were only useful in USSR... all because of money.

There were one He!! of a lot of 38's and 47's left after the Great Unpleasantness that didn't have to be 'bought' again..and a lot more B-17s and B-24s than B-29s so why didn't we just cut the 29s loose if $$ and training was the factor?

Doubt that was the factor but sure wish 47s had been used in Korea - that wasn't the war we expected to fight (as usual)

Regards,

Bill

 

[renrich]

I see your point and it is well taken, on the deck ,in air to ground, the 47 was the weapon of choice, from sea level to 25000 feet where the vast majority of acm took place, the 51 was a good choice especially if one had his eye on the fuel gauge. That is the reason I have always and still do maintain the US should have given Republic a contract to build F4U1s with that 361 gallons of internal fuel, 1500 miles of yardstick range, no tail hook, no folding wings, instead of P47s, and a lot of 8th air force crew would have been saved in 1943, before the P51B got into the fight.

 

[davparlr]

As you know there are all kinds of performance figures floating around on all a/c from ww2. My numbers I quoted were from a graph based on the MFR and the USAAF. I doubt very much that the P51D on average could touch 375 mph at sea level or 430 mph at 30000 ft.

Flight test by the Air Force (http://www.wwiiaircraftperformance.org/mustang/p51d-15342-level.jpg) and manufactures analysis indicate that the P-51D, in a clean configuration, was capable of about 375 mph at SL and about 430 mph at 30k ft. The test report appears of high quality with the aircraft identified by tail number and results in discrete test points. In addition, similar test on the P-51B with 44 fuel shows similar results, only a bit faster. I am not sure what justifies your doubts.

My graph shows it at about 417 mph at 30000ft.

What is your source?

That is the reason I have always and still do maintain the US should have given Republic a contract to build F4U1s with that 361 gallons of internal fuel, 1500 miles of yardstick range, no tail hook, no folding wings, instead of P47s, and a lot of 8th air force crew would have been saved in 1943, before the P51B got into the fight.

This makes no sense. The P-47 had a reputation as a very capable air-to-air fighter in ETO and there is no reason that techniques to increase the range on the F4U-1 would not have worked equally well on the P-47 with a result of similar ranges (some claim that the P-47 was not used for long range escort was because of politics associated with the theory that bombers could protect themselves. If this is true, the F4U-1 would have been as impotent as the P-47). Also, I suspect that ceiling is important for escort duties, preventing dive through attacks and allowing higher overall energy levels. Therefore, claiming that many 8th Air Force lives were lost because the P-47 was used by the Air Force rather than the F4U-1 is unjustified.

 

[renrich]

As I said before my numbers are based on graphs coming from the Mfr and the the Air Force. Everything I have ever read about the P51D says that it's Vmax at it's critical alt( slightly less than 25000 ft) was 435 mph. At that point the superchargers ability to maintain power begins to drop off significantly and if you could see the graph you would could readily see that at 30000 ft it could not do 430 mph. This data is from "America"s One Hundred Thousand" an exhaustively researched and footnoted book by an aeronautical engineer which goes into the design, development and manufacture and deployment of all US fighters in WW2. I recommend it to you. All I am saying as far as the F4U is concerned is that because of it's superior range in the 1 version that had fuel tanks in the wings, it could have stayed with the bombers longer than the P47s could and saved some lives in 1943. Also think about a redesigned version meant strictly for the AAF. Surely there could have been weight saving measures other than fixed wings and no tail hook that would have allowed the performance of the F4U to be even better. As it was the F4U1 in 1943 was already a better climbing and turning a/c than the P47 and it was a hands down better fighter until the fight got above 20000 feet or more. Just it's ability to use a much shorter field would have been an asset in England. Of course, I know why that idea was never tried as the AAF would never admit that an a/c designed to be a ship board fighter could never outperform a fighter designed for the AAF. The reason that the RN had no decent carrier fighters was that the RAF controlled design of the RNs a/c and they flat rejected the idea that a carrier fighter could compete with a conventional fighter. Part of the reason was also that in Europe( where they mistakenly thought in the 30s that only fighters with inline engines could compete) no fighter suitable radial engines were available. That inline engine idea was in vogue in the US also in the 30s and the only thing that kept the radial engine of high enough power to give the fighter the performance needed to keep up with inline engined fighters was the US Navy, that was responsible for it's own procurement of a/c. Thus the PW R2800. Back to the P51, I have no doubt that a specially prepared a/c with perhaps special fuel could exceed the figures I have quoted. I do think the figures I have quoted are more representative of the average production a/c. Whew, I am tired. This hunt and peck typing is hard.

 

[drgondog]

Quote:
a lot more Mustangs were lost to flak than fighters

That sounds far fetched.

Soren - True enough for quite a few Mustang groups in 8th FC

Here are the figures for the 355th FG from my own research which I will guarantee is better than any other source.

Losses
355 Unit Air Strafing Other Acc. Total
354 16 26 7 3 52
355HQ 1 1 0 0 2
357 16 34 9 2 61
358 12 30 15 3 60
SF 1 2 3 4 10
46.0 93.0 4.0 12.0 185.0

There is some 'judgement' that results in estimates of higher air losses than actually occurred.. but I assigned an air loss if contact was lost with a pilot on a mission in which enemy fighters were even seen much less engaged. That doesn't account for the possibility that the pilot could have gone down in bad weather, dropped to the deck and got shot down by flak or simply had a mechanical malfunction and lost oxygen - so the probability is that the ratio of flak losses to air losses is even higher than my MARC by MARC examination of every loss concluded.

The Other is a known situation where an engine over heated or a guy simply went into a dive in clear weather and didn't recover or a pilot was shot down by a B-17 - all with no fighters in area.

For the 8th AF Fighter Command the actual total losses due to fighters was about 638 out of 2338 fighters (P-47s, 51s, 38s and Spits) lost in all Operations including accidents, weather, flak and mechanical..

I say 'about' because I am using Kent Miller's Fighter Pilots and Units of the 8th AF and while pretty good I think he under estimates losses due to fighters and I 'rounded up' where a guy 'disappeared' where German Fighters were present rather than leave in UNK category.

Regards,

Bill

 

[renrich]

Just checked on combat radius for P47c-d and F4u1. P47 with internal fuel had a CR of roughly 225 miles. This with 370 gallons fuel and includes warmup, climb out, cruise, 5min at combat power, 15 min at military power, cruise back, fuel reserve of 30 min at min cruise power. F4U1 had CR of roughly 450 miles with 361 gal internal fuel with same profile. A significant difference. Which one would you rather have escorting you in your B17 or B24?

 

[davparlr]

As I said before my numbers are based on graphs coming from the Mfr and the the Air Force.

I gave a reference to an AF flight test report that identified a specific AF aircraft by number and you seem to disregard that data. Also, here is a manufacturer's data sheet with the manufactures logo that also disputes your input (http://www.wwiiaircraftperformance.org/mustang/na-46-130-chart.jpg). These seem to be high quality data. These are two different data sources reflecting the same information. Also, comparison to P-51B flight test data is consistent.

Everything I have ever read about the P51D says that it's Vmax at it's critical alt( slightly less than 25000 ft) was 435 mph. At that point the superchargers ability to maintain power begins to drop off significantly and if you could see the graph you would could readily see that at 30000 ft it could not do 430 mph.

The chart I referenced shows hp vs. altitude and reflects your comment about dropping off. However, airspeed does not drop off at the same rate as hp. It would if drag was a constant, but, as altitude goes up, drag drops off. Less hp is required to maintain airspeed. This is chart is consistent with other aircraft performance charts.

There is an interesting test report from a comparison test performed by Flight Test, U.S. Naval Air Station, Patuxent River, Maryland, titled "Evaluation and Comparison Trails of the P-51B and F4U Airplanes" (see http://www.wwiiaircraftperformance.org/f4u/p-51b-f4u-1-navycomp.pdf). Test included the F4U-1 and F4U-1A. These Naval test show that the P-51B was capable of 445 mph at 30000 ft. This is not inconsistent with the P-51D doing 430 mph at that altitude.

This data is from "America"s One Hundred Thousand" an exhaustively researched and footnoted book by an aeronautical engineer which goes into the design, development and manufacture and deployment of all US fighters in WW2. I recommend it to you

Hmmm, I not sure of what "exhaustive" means, since your data does not relate very well with what I have researched. I'll have to see about getting that book.

All I am saying as far as the F4U is concerned is that because of it's superior range in the 1 version that had fuel tanks in the wings, it could have stayed with the bombers longer than the P47s could and saved some lives in 1943. Also think about a redesigned version meant strictly for the AAF. Surely there could have been weight saving measures other than fixed wings and no tail hook that would have allowed the performance of the F4U to be even better.

The load carrying ability (gross minus empty weights) of the P-47C, F4U-1, and FG1 (F4U-1 with fixed wings) is a follows:

P-47C 3600lbs
F4U-1 3057lbs
FG1 3344lbs

As you can see, the F4U or FG1 could never carry as much fuel as the P-47 so it could never have a greater range.

As it was the F4U1 in 1943 was already a better climbing and turning a/c than the P47 and it was a hands down better fighter until the fight got above 20000 feet or more.

An escort fighter for B-17/24 should have optimum fighting ability between 20k to 30k+. This is where the F4U-1 begins to fade. I fail to see the F4U-1 advantage here.

Just it's ability to use a much shorter field would have been an asset in England.

I am not sure this was important in '43 England.

Of course, I know why that idea was never tried as the AAF would never admit that an a/c designed to be a ship board fighter could never outperform a fighter designed for the AAF. The reason that the RN had no decent carrier fighters was that the RAF controlled design of the RNs a/c and they flat rejected the idea that a carrier fighter could compete with a conventional fighter.

I am sure this is true.

That inline engine idea was in vogue in the US also in the 30s and the only thing that kept the radial engine of high enough power to give the fighter the performance needed to keep up with inline engined fighters was the US Navy, that was responsible for it's own procurement of a/c. Thus the PW R2800.

I do not agree with this statement. It is true that the in-line engine was in vogue but the Navy was not the only service using and proposing to use radial engined aircraft in the 30s. The AAF designed or built radial fighters in the 30s included, P-26, P-35, P-36, and P-43. In addition, and probably more influential to radial engine development, was the bombers, B-17, B-18, B-24, B-25, and B-26. There were probably more bomber funds provided to radial development than any other source.

Back to the P51, I have no doubt that a specially prepared a/c with perhaps special fuel could exceed the figures I have quoted.

The configurations of the tested aircraft are defined. Only minor modifications are mentioned in some instances and in other instances the aircraft were standard production aircraft. The only fuels used in these test were those available operationally, except where the fuel were being tested for proposed for use (like higher octane). These fuels were later operationally implemented.

I do think the figures I have quoted are more representative of the average production a/c.

Average performance of in-use aircraft is usually below those that are flight tested. However, this applies across the board to all aircraft. You cannot claim data is not good for one aircraft because it is not "average" and then compare that to the tested values of another aircraft. Since "average" performance is very difficult to get a handle on, comparing performance to "tested" levels is much more consistent and is a better way to compare aircraft.

Just checked on combat radius for P47c-d and F4u1. P47 with internal fuel had a CR of roughly 225 miles. This with 370 gallons fuel and includes warmup, climb out, cruise, 5min at combat power, 15 min at military power, cruise back, fuel reserve of 30 min at min cruise power. F4U1 had CR of roughly 450 miles with 361 gal internal fuel with same profile. A significant difference. Which one would you rather have escorting you in your B17 or B24?

Neither one of these planes could make it to Berlin. Both would have had to have been modified to carry extra fuel. As mentioned above, the P-47 had equal or better fuel carrying potential with drop tanks. I like the larger internal fuel capacity and it would probably have reduced some bomber exposure (although the P-47 could be modified for more internal fuel, in fact, the P-47D had 370 gal internal fuel). I do not think the F4U-1 would have made much of a difference. These planes were very similar but tuned to perform at different envelops, the P-47 at high altitude and the F4U-1 at lower altitudes. Both could probably be tuned to do the others job (except carrier ops. No carrier would be long enough for a Republic aircraft to take off on).

I do think that the higher altitude operating range of the P-47 gives it a significant advantage for bomber escort, as what it was designed to do.

 

[Jank]

For late war P-47D, when the higher grade fuel was in use, the following test is impressive.

FLIGHT TESTS ON THE REPUBLIC
P-47D AIRPLANE, AAF NO. 42-26167
USING 44-1 FUEL
P 47D Performance Test
.
.
.

 

[renrich]

Since you seem to be very interested in this stuff, I am sure you would be very pleased with the book and if you get a copy, you will see what I mean by exhaustively researched. I could not read the graph in the test report you mentioned. The p51b was faster than the D model as the D was heavier and there was a drag penalty for the bubble canopy but I do not find it inconsistent that that the speed would drop off more than 5 mph from around 24000 to 30000 ft. After all that is a mile higher. The same book in the graph on the Vmax of the F4U4 shows a drop of it's speed from just over 25000 ft to 30000 ft of from 446 mph to about 436 mph a spread of 10 mph. At any rate those numbers are tactically insignificant. As far as the ranges are concerned, the P47 would use more fuel at cruise than the F4U because it had a bigger cross section and more fuel in climb because it was around a ton heavier. Actually, the CR I quoted you was on the later model D version the C and early D only carried 305 gallons of fuel and that only gave the a/c a range of 800 miles at 10000 feet with no provision for warm up, takeoff, climb out, cruise, combat, cruise back and fuel reserve. Under the same conditions the F4U1 with 361 gallons of fuel could go twice as far. To put it simply the Corsair got better gas mileage than the Thunderbolt. Just as the Mustang with a Merlin got better gas mileage than a Kittyhawk with the same engine.

 

[drgondog]

Rhttp:
//www.wwiiaircraftperformance.org/f4u/p-51b-f4u-1-navycomp.pdfenrich -

I thought I would make your day - it is an official US Navy Flight Test Comparison of an F4U-1 versus a P-51B.It will state that the 51B is faster above 25,000 feet and in a dive but in all areas inferior to the F4U.

If you read between the lines however (remember it is not impossible for a Naval officer to be persuaded by higher command that they don't WANT an aeroplane from the USAAF - and you reflect that the Navy has only ONCE bought an airframe that was tainted by the USAF- the FJ version of the F-86)

You will note the following:

No comparison Climb curves from SL,From 5,000 from anywhere

No comparison curves for Turn or Roll

NOTHING except HP available (think and R2800 has more HP than a Packard Merlin -sure) but no HP to weight or Acceleration curves to look at things like acceleration at various altitudes.

A 'footnote' that the props are changed from standard 13'3 to 13'11 on the F4U but no recommendation that the fleet adopt such a flight test experience!

No corresponding change on the 51B nor any NA engineers on site

A footnote that the F4U wing folding fairings are sealed and cowl flaps tuned

A footnote that the War Emergency Power is boosted from Standard 60" to 65".

A footnote that 'equivalent fuel led to equivalent range" but no footnote to note that the 51B used a lot LESS fuel for 'equivalent range"

And finally no note on the version of the 51 B (its a -7 representing most of the first deliveries before March 1944 and the program had two major improvements in next three months)

Do ya think the Navy wanted a fair trial?

the 51 could either out turn or hold it's own, ditto acceleration (all depending on altitude and load of course), had very close to initial climb rate at SL was slower in climb until 20K+ then climbed faster than the F4U.. Both ships rolled well

Neither wanted the 'other guy' to have either ship. These two were as close to dead even as any two separate fighters in the world.

But it's funny how one controls the tests, isn't it?

Regards, Bill

 

[Soundbreaker Welch?]

Yeah!

 

[renrich]

I had read that report previously several times and had noticed the discrepancies although not as many as you. Another interesting thing about the report was that there were two P51s a B and a C. As I am sure you know the main difference between a B and C was that the latter was built at a new plant in Dallas. The C had so many defects that it was dropped from the study. Teething problems from the new assembly line? Reminds me of the difference between the quality of the Vought Corsairs and the ones built by Brewster. I wonder if the US did not try to foist as many of the Brewster builds on the British as possible. An interesting comparison test would have been the F4U4 and the P51D. The 4 was a hotrod and the D was heavier and more draggy than the B so the margin in performance would have been different. On this forum previously I have tried to advance the notion that many of these performance reports on the web, while authentic, may not have been objective and might not represent performance available in production a/c. Thank you for your detailed and specificpost.

 

[drgondog]

Mike Williams - owner of the very fine website which posts the many flight test reports as well as Mustang Encounter Reports - is the single best reference and the place you have to start with.

All the ones I posted earlier were in fact Official USAAF Reports in one form or another - whether tabular or narrative... same with Dave.

Yes the F4U-4 was a hotter ship - but here's two items you need to deal with. It was a later model and came into production about a couple of months before the P-51H so those two would be better for time based comparisons. Interestingly enough the P-51B-15 with improved Boost on the Merlin-3 was of course faster (and lighter) than the 51D and the 51H was not only 900 pounds lighter with same internal fuel and armament as the D but another 30Kts faster at 25,000.

I'm dealing from memory now but believe the initial climb at SL for the 51H was "around" 4700 feet per minute, had a lighter wing loading than the -4 (but less power) and both once again were within 10's of a foot per second in acceleration (F4U-4 slightly ahead).

Here's the question - so many sources claim that the F4U-4 out turns the 51 (name your model) at all altitudes.

But the 51B and H had lower to really lower wing loading than the F4U. Physics and aero suggest that the Corsair doesn't out turn 51 unless at really low speed - has anyone ever done a side by side turn test/comparison?

The charts would have looked similar - 51H faster and maybe slightly more agile on the deck and really come ahead above 25,000 feet while the F4U-4 will out roll it everywhere and be faster and climb slightly better from 5,000 to 20,000 +

Different Missions and not much to choose from. Difference is like Blonde vs Brunette on radial vs inline (51 will always - forever- loose energy slower and go farther on same fuel). If ground support is what you want F4U-4 clearly tougher and carry bigger load. If high altitude escort is the game then 51 is what you want. (WWII)

Which is NOT what Korea was all about for 18th and 35FBW with 51's - they needed 47's or (gasp) F4U-4/5's (or ADs)

Regards,

Bill

 

[renrich]

My reference of choice is "America's One Hundred Thousand" by Francis H Dean. One of the last sections in the book compares US fighters as to many of their performance characteristics. It is a very technical book,(written by an aeronautical engineer), and as far as turning is concerned with no flaps the relative performance is as follows in this order,(best to worst), FM2, P63A-9, P61B-1, F6F5, P51D-15, P38L, P47D-30, F4U-1D. As one can discern, turning does not guarantee superiority and does not necessarily translate to maneuverability.

 

[Snautzer01]

For me the il 2

awfull lot build , got great press, but also very many were shot down.

Bit like throwing so much gasoline on a fire that it kills it

regards

Snautzer

 

[renrich]

Another factor to consider in any discussion of the relative merits of F4U4 and the P51 H is that the F4U4 had a service ceiling of 41400 ft so it was no slouch at getting up there and it's critical altitude was 26200 ft where it got it's 446 mph TAS. From a practical point of view I wonder how much acm with recip engines took place at altitudes above 30000 ft. Other factors to consider might be controllability and ammo load. I have read in a number of places that the Mustang could be a handful in certain flight regimes whereas the Corsair had the reputation of being a sweet handling plane in the air with excellent control force modulation throughout. The Corsair of course had an ammo load of 2350 rds of 50 cal. I wonder what the H carried. By the way, it is my understanding in a turning fight the Corsair was improved vastly by 10 or 15 degrees of flap. Corsair turning ability was impaired by the right wing spoiler which more or less cured the left wing drop. I read somewhere that Hub Zemke spent time in a LW POW camp because he lost a wing on his P51 in a thunderstorm. As you said for long range fighter escort the P51 was the obvious choice. For a carrier capable fighter the Corsair hands down. For all the other roles except possibly the interceptor job, seems to me the Corsair comes out on top.