Hurricane IIc vs. B-17s B-24s

[Colin1]

Because highlighting a plane's alleged performance advantage at a height where very little actual combat took place...

There's an explanation in there somewhere
why do you suppose very little actual combat took place at 32,000ft? Because pilots found it disagreeable? Or because one side couldn't actually get to 32,000ft or at least not in any numbers? If you are penetrating enemy territory in large, strategically significant numbers escorting bombers capable of tremendous damage and notwithstanding this, there's still 'very little actual combat taking place' then your performance advantage isn't alleged, it's real.

The performance margin between the P-51 and its principal Luftwaffe rivals closed beneath its 'performance advantage height' of 25,000ft.

 

[Shortround6]

Because highlighting a plane's alleged performance advantage at a height where very little actual combat took place while either downplaying or not mentioning at all those lower altitudes where combat did take place tends to give a skewed picture. Same goes for situations where a plane subtype that saw little or no combat gets used in place of a more common sub-model.

No single piston powered aircraft could be optimized for peak performance at all altitudes. Compromises had to made. The question is wither the compromises were so sever as to seriously limit the planes combat ability at the altitudes it was not designed for.

The Americans spent a lot of time and money trying to develop and deploy bombers that would operate at 30,000ft and above. The British had several high altitude projects going including high altitude interceptors (see Westland Welken). Germans had a number of high altitude projects and some operational recon planes (JU 86).
Even the French had a prototype bomber with a third engine in the fuselage driving a supercharger for the wing mounted engines in 1939-40.
It turned out that high altitude operations were harder than it was first thought but without 20/20 hindsight who would have neglected or written off combat over 30,000ft when planning aircraft in WW II? With 2-4 years from issuing the requirement to getting operational aircraft in squadron service waiting until the enemy is overflying you at 35,000-45,000 ft is a little late to be placing orders.

 

[renrich]

Shortround, in my earlier post I was using a direct quote from a book written by an experienced pilot, test pilot and aero-engineer. I won't try to argue any points about drag caused by super chargers or turbo super chargers because I don't know that much about it. Linnekin flew operationally, Hellcats, Bearcats, Corsairs, Panthers, Crusaders, et al. and his opinions seem worthy of consideration. I have mentioned this before, also, one of my many uncles was an IP during WW2 and flew P39s and P47s among others. He told me that when he flew P47s and they went to gunnery ranges they would often be bounced by F4Us and that they could not compete with them. I doubt the Corsair could compete with a P47 much above 25000 feet so those mock dogfights must have occurred at lower altitudes. In Blackburn's book about the Jolly Rogers, I seem to remember mention of the Corsairs superiority over P47s and the P47 pilots trying to get them to go upstairs which the Corsair pilots sensibly declined.

The interesting thing about the 1944 fighter conference which Davidicus mentioned is that the F4U4 was at that conference and was included in some of the voting but not all. In some of the votes the F4U4 came in BEHIND the F4U1D. I don't get that because the F4U4 was a much better performer than the F4U1D and I have read in many places that it was the nicest flying Corsair of all. I guess we will never know.

 

[renrich]

Shortround, in my earlier post I was using a direct quote from a book written by an experienced pilot, test pilot and aero-engineer. I won't try to argue any points about drag caused by super chargers or turbo super chargers because I don't know that much about it. Linnekin flew operationally, Hellcats, Bearcats, Corsairs, Panthers, Crusaders, et al. and his opinions seem worthy of consideration. I have mentioned this before, also, one of my many uncles was an IP during WW2 and flew P39s and P47s among others. He told me that when he flew P47s and they went to gunnery ranges they would often be bounced by F4Us and that they could not compete with them. I doubt the Corsair could compete with a P47 much above 25000 feet so those mock dogfights must have occurred at lower altitudes. In Blackburn's book about the Jolly Rogers, I seem to remember mention of the Corsairs superiority over P47s and the P47 pilots trying to get them to go upstairs which the Corsair pilots sensibly declined.

The interesting thing about the 1944 fighter conference which Davidicus mentioned is that the F4U4 was at that conference and was included in some of the voting but not all. In some of the votes the F4U4 came in BEHIND the F4U1D. I don't get that because the F4U4 was a much better performer than the F4U1D and I have read in many places that it was the nicest flying Corsair of all. I guess we will never know.

 

[DAVIDICUS]

"The interesting thing about the 1944 fighter conference which Davidicus mentioned is that the F4U4 was at that conference and was included in some of the voting but not all. In some of the votes the F4U4 came in BEHIND the F4U1D. I don't get that because the F4U4 was a much better performer than the F4U1D and I have read in many places that it was the nicest flying Corsair of all. I guess we will never know."

The reason the rank for the F4U-4 was so low may be that relatively few pilots at the conference actually flew the aircraft. The Report lists the breakdown of comment cards turned in by pilots who flew the aircraft. Only three were turned in for the F4U-4.

The P-47D had 29 comment cards.

The P-51D had 38 comment cards.

The F4U-1D had 28 comment cards.

The P-47M also didn't place in the rankings even though it had a clear performance advantage over the P-47D. I suspect that the reason for its rank in relation to the P-47D is the same as the reason for the F4U-4's rank in relation to the F4U-1D. (It also had few comment cards)

Related to Shortround6's comment, I recall that Robert Johnson, in his book, said that German fighters sometimes would try to sneak in at over 35,000ft. I'm frankly not sure what weight to assign to all the conflicting anecdotal accounts of pilots engaging in mock combat. Renrich's post that the Helldiver, aggressively flown, presented as much trouble as a late model P-47D was interesting. There is a person here on this forum (I don't recall his name) who recounted his father's experience flying mock combat in P-47N's against F4U-4's. He stated that the Thunderbolt pilots would try to get the Corsairs to come up over 15,000ft and the Corsair pilots would try to get the Thunderbolts to engage below 15,000ft. Each knew where their strengths and the other's weaknesses were. He also said that the P-47N would out roll and out zoom the F4U-4.

His father also flew P-51's and his father's opinion was that the P-51 was better than the P-47D under 30,000ft and that while the P-51 did most things better than the P-47, the P-47s most important advantage was that it would bring you home. There is a post I put up with pictures of damage that P-47's have absorbed and still managed to bring their pilots home.

http://www.ww2aircraft.net/forum/aviation/tree-trimming-army-air-force-style-24161.html

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[Nikademus]

No single piston powered aircraft could be optimized for peak performance at all altitudes. Compromises had to made. The question is wither the compromises were so sever as to seriously limit the planes combat ability at the altitudes it was not designed for.

<snip>
It turned out that high altitude operations were harder than it was first thought but without 20/20 hindsight who would have neglected or written off combat over 30,000ft when planning aircraft in WW II?

I think you understand my point and I agree with both billets above. On the former, that was why i agreed with the Renrich's caution and expansion regarding the P-47's overall performance , who's attributes tend to get caught up in black and white comparisons, in part because much of it is speculation as there was very little fighter combat above 30,000 feet. Having seen may declarative posts (on other boards) about P-47's dancing all over the heads of Axis aircraft as if they were WWI relics at such altitudes was what led me to ask the basic question....how much actual combat supports such notions? I found there to be little to none which ties in to the 2nd billet. Indeed it was alot harder to fight at such altitudes. Even simply chasing down high flying recon planes proved challenging in terms of getting there and the aerodynamics involved in controlling one's plane.

 

[davparlr]

One man's account of P47 prowess in ACM and this was undoubtedly not at the P47s best altitude. Ralph Linnekin, "80 knots To Mach 2" " That useful altitude reference is in honor of the P47, which is difficult to categorise. The N version is credited with something on the order of 469 mph, but at 32000 feet. What reciprocating engine airplanes actually fought at 32000 feet?

Quite helpful if you had to deal with a Ta-152, which, by the way, it was as fast or faster from 15k ft to 35k ft.

It may be useful to fly that high, but at what cost. The P47 was a very good airplane with a fine combat record. It was not, however lauded as a sterling performer.

Actually it was lauded by the Joint Fighter Conference as the best fighter above 25k ft, which is important in that the B-17 and B-29 flew at that altitude or higher. It certainly held the high ground in Europe.

The airplane had a huge turbo supercharger that, by a combination of drag and mechanical power bleed off must have caused a substantial performance degradation at other than optimum altitudes.

I don't know. The P-47M/N generated 2600 hp at SL and 2800 hp form 5k to 33k. I know of no other single engine aircraft that comes close to this power.

I know a couple of people in a Bearcat squadron who had an inadvertant encounter with four late model P47s one day in 1947. ( Inadvertant, hell. The Bearcats jumped them. What did you expect. The P47s were there.) It was no contest- partly because the Bearcat, below 10000 feet, could do absolutely everything better than anything else with a propeller

Well, bragging about jumping someone in you own back yard and winning is no big thing, kinda like a Zero pilot bragging about beating an F4U in a turning fight.

Lets look at some comparisons of the F8F-1, P-47D-25 with 44-1 fuel (post May, '44), and P-47M/N, with equal loads (using F8F loaded weight minus empty weight or 2316lbs),

Loaded weight
F8F-1 9368 lbs
P-47D-25 12515 lbs
P-47M 12739 lbs
5k
HP available-power to weight-airspeed – rate of climb
F8F-1 1900 hp (est based on F4U pwr profile) -.203 hp/lb – 400 mph (est) – 4150 ft/min
P-47D-25 2700 hp – .216 hp/lb – 372 mph – 3510 ft/min
P-47M 2800 hp - .220 hp/lb – 385 mph – 3880 ft/min

15k
F8F-1 1850 hp - .197 hp/lb – 415 mph (est) – 3850 ft/min (est)
P-47D-25 2700 hp – .216 hp/lb – 417 mph - 3500 ft/min
P-47M 2800 hp - .22 hp/lbs – 418 mph – 3560 ft/min

20k
F8F-1 unk hp – unk – 421 mph (max speed) – 3650 ft/min
P-47D-25 2700 hp - .216 hp/lb – 435 mph – 3300 ft/min
P-47M 2800 hp - .22 hp/lb – 437 mph – 3300 ft/min

Just looking at the comparison numbers, it is apparent that the late model P-47s were extremely powerful aircraft with even the equally loaded P-47D-25 having a better power to weight ratio, thus acceleration, than the F8F-1. An equally loaded P-47M would easily out accelerate the F8F-1 and had very similar performance above 10k ft and at 20k ft, would not only out accelerate the F8F-1 but also leave it behind. The F8F-1 was certainly a maneuverable hot rod and the P-47 pilot would have to make sure he had a significant advantage in attacking below 15ft or go somewhere else, like they always had to do. However, they could always pounce from above.

P-47D data was taken from 44-1 fuel test with corrections for weight.

P-47M data was from various official sources, either military flight test or supplier data.

F8F-1 data was based on fixed point data of, 2100 hp and 382 mph at SL, max speed of 421 mph at 19,700 ft, and 1850 hp at 15,500 ft. Estimates beyond this were based on fixed point data modified by typical F4U-4 performance in hp, climb and speed. This is sometimes dangerous, but is probably a reasonable rule of thumb.

and at low altitudes could out accelerate most contemporary jets.

I kind of feel that the SNJ would out accelerate a contemporary jet.

Nonetheless, our guys said that AD Skyraiders and even SB2C Helldivers flown aggressively had at other times given them as much trouble as the P47s.

A lightly loaded attack bomber, especially an AD with 2500 hp and low wing loading could certainly be a formidable adversary in turning fight, same too with the SB2C only not as much so, but again, you don't want to turn with one.

 

[renrich]

Thanks, Davidicus, for clearing up the issue about the F4U4. I have always wondered about that. An amusing story about F4Us in Guyton's book. On May1, 1945, three land based Marine pilots in F4Us on a 30000 foot patrol from Okinawa wandered too far at sea and ran low on fuel. They were almost out of fuel when CV Yorktown heard their distress calls and directed them to land aboard. None had ever made a carrier landing. " One, after a perfect landing asked: What was that man doing waving those paddles back there?" " Brother,' he was told, " he was the landing signal officer and he was giving you a wave off."

 

[renrich]

Thanks, Davidicus, for clearing up the issue about the F4U4. I have always wondered about that. An amusing story about F4Us in Guyton's book. On May1, 1945, three land based Marine pilots in F4Us on a 30000 foot patrol from Okinawa wandered too far at sea and ran low on fuel. They were almost out of fuel when CV Yorktown heard their distress calls and directed them to land aboard. None had ever made a carrier landing. " One, after a perfect landing asked: What was that man doing waving those paddles back there?" " Brother,' he was told, " he was the landing signal officer and he was giving you a wave off."

 

[renrich]

Dav, my reading on B17 missions in the ETO indicates that they seldom flew missions as high as 30000 feet. More like low twenties to twenty five thousand feet. Loaded B24s even lower.

 

[renrich]

Dav, my reading on B17 missions in the ETO indicates that they seldom flew missions as high as 30000 feet. More like low twenties to twenty five thousand feet. Loaded B24s even lower.

 

[drgondog]

Dav, my reading on B17 missions in the ETO indicates that they seldom flew missions as high as 30000 feet. More like low twenties to twenty five thousand feet. Loaded B24s even lower.

That would correct. The Early Days with the Brits were the only missions really flown at 30,000 feet.

SOP was for the Forts to fly 22K to 26+K with most missions flown at 24-26,000 feet (low to high boxes) and the B-24s at 20-22K..

 

[Colin1]

Dav, my reading on B17 missions in the ETO indicates that they seldom flew missions as high as 30000 feet. More like low twenties to twenty five thousand feet. Loaded B24s even lower.

Would this be a command preference, or down to platform limitations (esp the ability of the crew to operate at 30,000ft) and bombing accuracy?

 

[Nikademus]

Ceiling limits while loaded, balancing bomber accuracy with the threat from flak (and fighters) and impact on crews and equipment.

 

[Colin1]

Ceiling limits while loaded, balancing bomber accuracy with the threat from flak (and fighters) and impact on crews and equipment.

...is pretty much the perfect answer
So we're coming to the close of the war and we're learning. We now know what it takes to get a platform up there and this know-how is manifested in aircraft like the P-47N, the B-29 and from Germany, the Ta152.

The problem with the end of the war (for Germany) is that she has precious few resources to see off the B-17/B-24 and incumbent escort raids, let alone develop and build for a fight at a new altitude; the Ta152 was good enough, just not numerous enough (or in-time enough). The lack of combat at 30,000ft, for me, can be attributed to a lack of opposition rather than any lack of plausibility.

 

[davparlr]

Dav, my reading on B17 missions in the ETO indicates that they seldom flew missions as high as 30000 feet. More like low twenties to twenty five thousand feet. Loaded B24s even lower.

I worded that poorly. I meant that the B-17 flew at 25k, but B-29 flew higher. P-47Ns were active in the Pacific.

 

[Shortround6]

Dav, my reading on B17 missions in the ETO indicates that they seldom flew missions as high as 30000 feet. More like low twenties to twenty five thousand feet. Loaded B24s even lower.

This may be quite true but what altitude were they designed to fly at?

And how much higher should the escorting fighters be able to fly/fight?

Germans were fitting Nitrous oxide systems for use at what altitudes?

Germans were fitting pressure cabins to some 109Gs

Germans had been working on two stage superchargers in addition to turbos and had tried the central auxiliary engine on both the Henschel 130 and the Do 217

And I guess the Navy had it wrong when they ordered the F4U-5 with the sidewinder supercharger set up to act as high altitude planes over the Bearcats?

 

[DAVIDICUS]

While not a rule of thumb, it was not rare at all to have enemy aircraft approaching at 28,000ft and higher. I pulled these in about 15 minutes.

P-51's

http://www.spitfireperformance.com/mustang/combat-reports/4-fiedler-29march44.jpg

http://www.spitfireperformance.com/mustang/combat-reports/4-grounds-19july44.jpg

http://www.spitfireperformance.com/mustang/combat-reports/4-hofer-24may44.jpg

http://www.spitfireperformance.com/mustang/combat-reports/4-lajeunesse-30may44.jpg

http://www.spitfireperformance.com/mustang/combat-reports/20-black-14jan45.jpg

http://www.spitfireperformance.com/mustang/combat-reports/20-fiebelkorn-28sept44.jpg

http://www.spitfireperformance.com/mustang/combat-reports/20-jones-d-14jan45.jpg

http://www.spitfireperformance.com/mustang/combat-reports/20-kelso-14jan45.jpg

http://www.spitfireperformance.com/mustang/combat-reports/20-nichols-14jan45.jpg

P-47's

http://www.wwiiaircraftperformance.org/p-47/er/353-kinkade-14oct43.jpg

http://www.wwiiaircraftperformance.org/p-47/er/353-newman-14oct43.jpg

http://www.wwiiaircraftperformance.org/p-47/er/361-webb-30jan44.jpg

http://www.wwiiaircraftperformance.org/p-47/er/353-maguire-27sept43.jpg

http://www.wwiiaircraftperformance.org/p-47/er/361-sedman-30jan44.jpg

http://www.wwiiaircraftperformance.org/p-47/er/361-lederer-30jan44.jpg

http://www.wwiiaircraftperformance.org/p-47/er/361-latimer-30jan44.jpg

http://www.wwiiaircraftperformance.org/p-47/er/353-lefebre-22dec43.jpg

http://www.wwiiaircraftperformance.org/p-47/er/355-woertz-29nov43.jpg

http://www.wwiiaircraftperformance.org/p-47/er/355-olson-21feb44.jpg

http://www.wwiiaircraftperformance.org/p-47/er/353-rimerman-27sept43.jpg


This one made me laugh out loud:

"After this I called for a join up of the Squadron at 18,000 on the bombers. My No. 3 and I flew about 70 degrees for a few minutes and came up on the B-17's again. I saw 4 P-51's chasing something so flew over to investigate and took a left turn over them. I had just about found out that it was an ME-109 but too late. Another one came from behind me and laid in several nice close 20mm. Two in the right wing root knocking out the flap, wheel, which burned out, and aileron. Two in the right elevator and several in the fuselage and prop. Those things give you a start for a while but you can usually bring a P-47 home. P.S. This is in no way to be used as an advertisement for the thing though. Well we got home to learn that two of the boys had shot the Jerry ---- so and so down. They didn't even let him jump out.

I claim one FW-190 destroyed because I saw him strike up and go down burning --- two FW-190's damaged as I saw the strikes. -- I also claim one P-47 to be repaired."

http://www.wwiiaircraftperformance.org/p-47/er/353-duncan-12may44.jpg

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[renrich]

SR, the F4U4 had a service ceiling in excess of 41000 feet. The F4U5 the same except it developed more HP. Please enlighten me as to what a "sidewinder supercharger" is.

 

[Shortround6]

For those who are interested there are several charts over on the Spitfire performance website.

One for the P-47 that is rather interesting: scroll down to the Oct 11 1943 test for the P-47D.

P-47 Performance Tests

This test lists altitude, manifold pressure, horsepower, turbo RPM, exhaust back pressure, and carb temperature in addition to speed.

This gives a pretty good idea of the operation of the turbo charger. It was basically idling at sea level with just about all pressure coming from the engine driven supercharger. The work a supercharger does goes up with the square of it's speed so at sea level the turbo was doing about 1/9 the work it would be doing at 31,000ft when it hit 22,000rpm.
Please note also the difference between critical altitudes in high speed flight and while climbing. The speed of the air entering the intake duct (speed of the aircraft) means that there is a higher pressure going into the turbo during high speed flight than while climbing so you get more pressure out.

This effect can also be seen in the Charts for the F4U:
F4U Performance Trials

Where the different altitudes for engine critical hight (no ram effect) and aircraft critical hight (with ram effect) are given.

Please also note the progressively lower altitudes going from normal power (max continuous) to military power power and, in later tests, War Emergency Power. The supercharger couldn't supply enough air to maintain the higher power ratings at the higher altitudes.