P-38 vs P-51: Full internal fuel dogfighting

drgondog · Feb 9, 2013

Don't disagree with your comments. The only tabular comparison I have seen is Chapter 5 Fighters Compared, pg 602-3 of America's Hundred Thousand.

They did not present actual turn times or radius, but expressed the turns as a Percent greater than the best ranked turner - the FM-2. They did not have either the P-40 or the P-39 which would have been a good comparison against Soviet data.

The ranking of the P-63 (@8780 pounds and 3G stall speed of 132mph) was 124% of the FM-2(@3G Stall 118.5), The P-61B-1(@27000 pounds 3G stall of 137mph) was 133%, F6F-5 (12500 w/3G stall of 139mph) was 138%, P-51D-15 (9500 w/3G stall at 159mph) was 179%, P-38L (@17488 w/3G stall of 170mph) was 205%, P-47D-25 (@14300 w/3G stall at 170mph) was 206% and the F4U-1D (@11,803 and 3G stall at 172 mph) was 206%.

What was interesting to me was that the max CL for the laminar flow P-63A-9 wing was 2.38 - the same as the FM-2. The Mustang had the lowest Stall CL max of 1.89. The F4U-1D had the worst Stall CL @3G with 1.48 - probably because of the spoiler under the right wing.

The P-61 and P-38 both had stall speed Max CL of 2.38. the P47 was 1.93 and the P-38 was 2.17.

The W/L of each for these tests were (FM-2) 28.5 , (P-63A) 35.4 , (P-61B) 40.7 , (F6F-5) 37.4 , (P-51D) 40.7, (P-38L) 53.4 , (P-47D) 47.7 , (F4U-1D) 37.6 .

Kryten · Feb 9, 2013

Tante Ju said:
I find it amusing because US report are generally the most through... and almost everyone produced some sort of estimate or measurements of the turn time of fighters. So, I find it difficult to believe that the USAAF never had an interest for such solid turn time figures, and would put up with with 'well we flew his pursuit plane against that pursuit plane, and pilots say the latter was a bit better in turns.'

Surely such figures must exist somewhere.. the Soviets did some tests with Allison Mustang (23 secs) and an early P-47D (26 secs), which does not seem unreasonable, but there is alway a way of error with foreign planes tested... also it difficult to extrapolate turn times from that to the Merlin Mustang, which was different in too many ways.

Even if they existed unless they are compared in exactly the same way they again become meaningless, what altitude, speed, weight, power settings, conditions on the day etc etc!

you would then need to take several of each type and work off the average peformance, otherwise you may simply be testing a exceptional/sub standard model!

I have seen many reports of aircraft etsted that were declared not representative of type!

fastmongrel · Feb 9, 2013

A P38 driver who gets into a turning battle is doing it wrong.

gjs238 · Feb 9, 2013

fastmongrel said:
A P38 driver who gets into a turning battle is doing it wrong.

AVG learned that with P-40's.

FLYBOYJ · Feb 9, 2013

fastmongrel said:
A P38 driver who gets into a turning battle is doing it wrong.

Or extremely skilled...

"I was able to stay inside this maneuverable little rascal's left turn for 360 degrees while doing about 90MPH, and at less than 1000' above the water. That P-38J was bucking and shuddering all the way around in what was nothing more nor less than a controlled stall. I was so close to the Oscar that his engine oil covered my windshield. For the last half of the turn I was shooting at a dark blur that finally burst into-flames. When I saw the Oscar explode I pulled up and started calling for someone to lead me home cause I couldn't see through the oil on my windshield."

Secrets of a P-38 Ace. John Tilley's electrifying story

MikeGazdik · Feb 9, 2013

What amazes me in Drgondog's post is the turning radius of the P-61 ! I have read some on that bird and love it. That turn would have to have been using the full span flaps I surpose. Could you imagine looking over your shoulder and seeing that big black evil looking twin hanging on your tail in a turn???!!!!!!

tomo pauk · Feb 10, 2013

Unlike most of the fighters, the Fowler flaps of the P-38 were enabling tight turns. The Japanese fighters were also using the 'butterfly flaps', so I can agree that the best thing got the P-38 driver would be to make a slashing pass vs. Japanese opponent.
A pro could use the differential enigine power setting, too, to increase it's turning abilities.

fastmongrel · Feb 10, 2013

FLYBOYJ said:
Or extremely skilled...

"I was able to stay inside this maneuverable little rascal's left turn for 360 degrees while doing about 90MPH, and at less than 1000' above the water. That P-38J was bucking and shuddering all the way around in what was nothing more nor less than a controlled stall. I was so close to the Oscar that his engine oil covered my windshield. For the last half of the turn I was shooting at a dark blur that finally burst into-flames. When I saw the Oscar explode I pulled up and started calling for someone to lead me home cause I couldn't see through the oil on my windshield."

Secrets of a P-38 Ace. John Tilley's electrifying story

Very skilfull but how many P38 drivers could do this without getting it wrong. Close to a terminal stall at less than 1,000 ft there is zero margin for error if the pilot so much as hiccuped he would have been in the drink. What the best 1% can do is not what the other 99% should even think of attempting.

I am a very green microlight pilot and there is a member of my flying club who can do astonishing things, I watched him land into a strong breeze once vertically light as a feather by blipping the throttle and balancing on the edge of stalling. If I tried it I know the laws of gravity would kill me I simply am not one of those rare breed.

FLYBOYJ · Feb 10, 2013

fastmongrel said:
Very skilfull but how many P38 drivers could do this without getting it wrong. Close to a terminal stall at less than 1,000 ft there is zero margin for error if the pilot so much as hiccuped he would have been in the drink. What the best 1% can do is not what the other 99% should even think of attempting.

I am a very green microlight pilot and there is a member of my flying club who can do astonishing things, I watched him land into a strong breeze once vertically light as a feather by blipping the throttle and balancing on the edge of stalling. If I tried it I know the laws of gravity would kill me I simply am not one of those rare breed.

Actually I think there were more pilots in the PTO that could have done this. "Training and experience." Once a pilot is given the time to master their aircraft, they could push the envelope to the absolute limit, unfortunately during WW2, this was not always the case.

As you have the opportunity to fly more and learn your aircraft, you too will find that as time goes on, you'll learn to do maneuvers that you thought you were not capable of doing

GregP · Feb 12, 2013

All too true. And if you are a wingman, how often do you get to practice your skills? What you must as a wingman do is fly good formation and keep your eyes on a pivot.

So my take is you must make flight leader before you can play around and learn the maneuvering skills you need in combat.

Sometimes they never made it that far. Many P-38 pilots got into combat with very little time in the aircraft ... not a good combination.

stug3 · Feb 17, 2013

I thought P-51 fuselage tank center of gravity problems only arose with the bubble top D model, and was the main reason many pilots preferred the P-51B?

drgondog · Feb 17, 2013

stug3 said:
I thought P-51 fuselage tank center of gravity problems only arose with the bubble top D model, and was the main reason many pilots preferred the P-51B?

No. The P-51B-5 line block was changed to P-51B-7 block when the 85 gallon tank was installed at NAA. The P-51B-1 and -5's in the ETO were modified in March 1944 to install the 85 Gallon Tank and a "+" symbol was placed on the fuselage near the CG. The P-51B-10 43-7113 (#1) was the first factory installed 85 gallon tank in production series.

EDIT: The AAF so designated the P-51B-5 to -7, and C-1 to C-3 following each Depot modification but the practice of changing the data block and IARC's and Engineering records was very inconsistent.

All subsequent Mustangs had the 85 gallon tank until the P-51H - which carried a 50 gallon tank, and had increased fuselage length and re-designed tail to eliminate the stability issues inherent in the Merlin powered Mustang combined with increased gross weight and 85 gallons/500+ pounds aft of the CG on take off.

stug3 · Feb 17, 2013

Frank Stewart · Aug 13, 2016

davebender said:
I don't think either aircraft was particularly good for dog fighting. Neither was P-47. These aircraft need to escort bombers @ 25,000+ feet.

The P-51 could out roll the P-38 but the P-38 could out turn the smaller plane once established in the turn. This trick was a compliment6 of the maneuvering flaps, and, or the twin engines blowing over most of the wing at very low speeds WO prop torque causing the plane to stall.
The later models of the P-38 with the chin inter-coolers were also faster than the P-51D. (If the pilot broke the wire across the throttle gate to restrict use of WEP) It's a long story, but a good read if you look it up.
However niether plane was a great "Dog Fighter" and like all mono-plane fighters of the time should be used in the Zoom and Boom mode tactics exclusively!!!!

Frank Stewart · Aug 13, 2016

Tante Ju said:
I find it amusing because US report are generally the most through... and almost everyone produced some sort of estimate or measurements of the turn time of fighters. So, I find it difficult to believe that the USAAF never had an interest for such solid turn time figures, and would put up with with 'well we flew his pursuit plane against that pursuit plane, and pilots say the latter was a bit better in turns.'

Surely such figures must exist somewhere.. the Soviets did some tests with Allison Mustang (23 secs) and an early P-47D (26 secs), which does not seem unreasonable, but there is alway a way of error with foreign planes tested... also it difficult to extrapolate turn times from that to the Merlin Mustang, which was different in too many ways.

The best turn times and degrees per second figures will all be had at the slowest speed that the plane will pull the maximum G load the Pilot can stand! At that point in time few pilots could pull much more that four Gs for more than 5 seconds. The 1%ers could pull 6 or more Gs for as long as the plane could. That made dog fighting them irrational! No plane in the second world war could pull as much as TWO Gs with out slowing down drastically because of the large increase in "Induced Drag"! So pilots traded attitude for more speed to maintain the rate of turn until they were brush hopping at about 2/3 to 3/4 G!
The slower your plane could go and pull a certain level of G load, the tighter you could Dog Fight! At very low speeds the twin engined and contra-propped P-38 could out turn any other mono-plane fighter of the war! Not that I would recommend that tactic as low and slow just gives some other guy the opportunity to shoot you down.
This also leads to large errors in test numbers of foreign air craft flown by pilots who are not intimately familiar with said planes. The resulting conundrum of German "Experten" flatly stating their LE Slated Me-109s could out turn the Spitfire and British testers who stated just as vehemently that the opposite was true! When the facts show that they were both right at the right part of the Flight Envelope!

wuzak · Aug 13, 2016

The Bf 109 could only out-turn a Spitfire if the 109 pilot was an experten and the Spitfire pilot a novice.

Frank Stewart said:
At very low speeds the twin engined and contra-propped P-38 could out turn any other mono-plane fighter of the war!

I also doubt very much the claim that the P-38 could out turn any monoplane fighter of WW2.

Greyman · Aug 13, 2016

Sorry - I must break out my well-worn ULTIMATE TURN PERFORMANCE/MANEUVERABILITY ANECDOTE

I've got a great anecdote that, for me, put the somewhat nebulous 'turn performance' quality in perspective for all time.

From (then Flight Lieutenant) Wing Commander Hugh Godefroy DSO, DFC and Bar, Croix de Guerre with Gold Star (Fr), shortly before Dieppe.

At Duxford one day a US Army Captain arrived unexpectedly with a P-38. Like the other Air Corps pilots, he had no battle experience and asked if he could get somebody to dogfight with him in a Spitfire IXb. Flight Lieutenant Clive, implying that he was in charge, said he would be glad to cooperate. He would fly the Spitfire himself. We were all a witness to the P-38 outmanoeuvre Clive, even turning inside him. When they landed, Clive came into Dispersal sweating profusely and stated the P-38 could outmanoeuvre the IXb. The Captain asked if he could have that in writing to show his Commanding Officer.

'Certainly,' said Clive, 'I'll have it ready for you by lunchtime.'

Now, imagine if the story ended here, as it easily could have. Think of how us internet nerds would pour over this controlled, seemingly decisive 'combat'. How those that have some strange, personal investment in the performance of seventy-year old aircraft would either swoon or gnash their teeth at the outcome of this impromptu contest. It would have been 'ammunition' on forums and bulletin boards for decades.

However, it doesn't end there. Godefroy continues ...

I was convinced this was wrong, and pleaded with Campbell-Orr to let me fly against him before issuing any report. The Captain supported me in my request, and off we went. I was able to show that there was no way he could come anywhere near me in the Spitfire. To demonstrate the turning ability, I let him get on my tail. In two complete circles from this position, I was able to get in firing position behind him. The Captain was not a bit upset, he had come to learn the truth. I told him I thought a good pilot in a 109F would give him a lot of trouble.

Now here we have two mock combats with everything remaining constant except for the pilot of one of the aircraft - and we get completely opposite results. Something to keep in mind next time you're reading anecdotes on things like turn performance.

drgondog · Aug 13, 2016

Frank Stewart said:
The best turn times and degrees per second figures will all be had at the slowest speed that the plane will pull the maximum G load the Pilot can stand! At that point in time few pilots could pull much more that four Gs for more than 5 seconds. The 1%ers could pull 6 or more Gs for as long as the plane could. That made dog fighting them irrational! No plane in the second world war could pull as much as TWO Gs with out slowing down drastically because of the large increase in "Induced Drag"! So pilots traded attitude for more speed to maintain the rate of turn until they were brush hopping at about 2/3 to 3/4 G!
The slower your plane could go and pull a certain level of G load, the tighter you could Dog Fight! At very low speeds the twin engined and contra-propped P-38 could out turn any other mono-plane fighter of the war! Not that I would recommend that tactic as low and slow just gives some other guy the opportunity to shoot you down.
This also leads to large errors in test numbers of foreign air craft flown by pilots who are not intimately familiar with said planes. The resulting conundrum of German "Experten" flatly stating their LE Slated Me-109s could out turn the Spitfire and British testers who stated just as vehemently that the opposite was true! When the facts show that they were both right at the right part of the Flight Envelope!

While I largely agree with your post I would modify some of the comments.

The key to sustained turn performance is the state of equilibrium of Thrust (at max power) to Drag where Power Available matches Power Required. Power Available is reduced from straight flight power in turns and climb where the incremental Form Drag due to Angle of Attack (CL increase) plus major Cooling Drag increases occur plus Trim Drag plus Induced Drag increases - all due to CL increases from level flight.

The Max SUSTAINED Rate of turn while maintaining altitude, in Radians per second, is as you say - in the 2.0 to 2.7 range for most WWII fighters,

That said the Corner Velocity expressed in the V-n diagrams is based on Max N (G) attainable at CLmax for Design Stress Limit It is proportional to the Square Root of n, and W/L, and inversely proportional to Square Root of density and CL. This is maximum Initial Turn Velocity and Turn Rate based on structural limit.

This has nothing to do with calculations leading to maximum Sustained rates of turn which must take into consideration T=D.

grampi · Aug 24, 2016

wuzak said:
The Bf 109 could only out-turn a Spitfire if the 109 pilot was an experten and the Spitfire pilot a novice.

I also doubt very much the claim that the P-38 could out turn any monoplane fighter of WW2.

I do too...

FLYBOYJ · Aug 24, 2016

wuzak said:
The Bf 109 could only out-turn a Spitfire if the 109 pilot was an experten and the Spitfire pilot a novice.

I also doubt very much the claim that the P-38 could out turn any monoplane fighter of WW2.

The P-38 can and has out turned "monoplane fighters" for the same reasons you give for the BF 109 vs the Spitfire. I posted this on another thread...

"on my 3rd mission while in a P-38H model. The 2nd was an Oscar while I was flying in a J model. I was particularly proud of this one 'cause I was able to stay inside this maneuverable little rascal's left turn for 360 degrees while doing about 90MPH, and at less than 1000' above the water. That P-38J was bucking and shuddering all the way around in what was nothing more nor less than a controlled stall. I was so close to the Oscar that his engine oil covered my windshield. For the last half of the turn I was shooting at a dark blur that finally burst into-flames. When I saw the Oscar explode I pulled up and started calling for someone to lead me home cause I couldn't see through the oil on my windshield. "Pete" Madison was kind enough to oblige. When we got back to base, I had to crank down the side window and wipe a clear spot on the windshield so I could see enough to land the bird."

1st Lt. John Tilley, 431st Fighter Squadron, 475th Fighter Group

Secrets of a P-38 Ace. John Tilley's electrifying story

P-38 vs P-51: Full internal fuel dogfighting

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