P-38 Lightning vs P-51 Mustang: Which was the Better Fighter?

[drgondog]

This discussion reminds me a little of the discussion about how a wing creates lift. I had always thought it was Bernoulli's Principle until I read "Stick and Rudder" Was in an airliner one day and was sitting next to a pair of(I think) young aero engineers and I mentioned that lift was created by a wing pushing down on the air and the air pushing up. They looked at me like a heretic and started talking about Bernoulli and the air having to speed up over the airfoil and creating low pressure over the top. I then asked them how a wing created lift when the airplane is inverted. We had a lot of fun.

Roll on your back with slight forward pressure to give a freestream angle of attack on the 'original upper/now lower' airfoil.

Same principle as a curve ball. The original airfoil design approach is the Theodorsen Transformation in which the freestream flow velocity around a rotating cyclinder is mapped via complex variables to and airfoil shape.

The velocity on the rotating side which 'adds' rotational velocity vector to the freestream, is higher than the velocity over the opposite side in which the rotational velocity vector is subtracted from the freestream velocity.

Vtop = Vfs + Vr, Vbot =Vfs - Vr

The difference in Pressure is then 1/2 x rho x (Vtop>>2 - Vbot>>2) and multiply that by the cross sectional area of the ball gives you the force vector perpendicular to the freestream.. in the direction of 'lowest' pressure.

Strike! unless not enough rotational velocity is imparted by the curve-baller - in which case Home Run on the 'hanging (and slow) curve ball'

The kids were basically right.

 

[firstflight]

One thing we have to remember in the difference between the two fighters. First the ability of performance at altitude. For the P-38 there are manuvering altitudes that hender this great bird. Below 10,000 ft the aerobatics needed to servive this combat arena kept the pilot on his toes. not to say the plane could not handle the fight but the pilot had to stay sharp, much sharper. at 30,000 ft the operation at this altitude was much harder to get the power delevoped for the engagement. not to say it could not fight, but rather a better performer at a lower altitude. Plans for a better supercharger was in the works but much to late for the P-38.

The mustang however was a much better fighter to replace the p-38, because it hade the upgrade in power performance. This gave the 51 the advantage in the fight at any altitude.

Which is the better fighter? the question was asked?

The P-38.............Still shot down more planes in any sky.
You got to love those numbers.

Firstflight

 

[renrich]

Don't know where your numbers come from but I believe if you are saying the P38 had more kills than P51, you are misinformed. It was third in the PTO and way back in ETO.

 

[kool kitty89]

The power problems at altitude were due to the intercoolers in the wing LE on the P-38. This was solved in the J model and the P-38 had more power available at altitude than the P-51. (the turbochargers maintaining power better better as they didn't absorb engine power lake a mechanical supercharger)

The P-38G also introduced maneuvering flaps that (combined with ~100 hp increase/engine over the F) allowed the G to gain 180 degrees on the F in a 360 degree turn! (double the turn rate)
P-38 Performance Trials

http://www.wwiiaircraftperformance.org/p-38/fighter-comp-chart.jpg

See also:
P-38L Climb Chart
P-38L Roll Chart
P-38L Speed Chart

 

[ccheese]

Don't know where your numbers come from but I believe if you are saying the P38 had more kills than P51, you are misinformed. It was third in the PTO and way back in ETO.

P-38 Lightning's would be credited with more enemy kills in the Pacific Theater than any other aircraft type, which is impressive considering the amount of carrier-based battles occurring throughout the war.

Lockheed P-38 Lightning - History, Specifications and Pictures - World Military Aircraft

Sounds impressive to me....

Charles

 

[renrich]

According to my sourcesTO-F6F--5257 kills, F4U--2155 kills, P38--1700 kills, F4F--1408 kills. This has been discussed on other threads, specifically best Pacific fighter and these numbers seem to be authentic. In ETO-P51--4239 kills, P47--2686 kills, P38--497 kills, F6F--8 kills, F4F--2 kills. Med- P38, 1431 kills, P51--1063 kills. I am pretty sure that USN did not give credit for kills on ground, not sure about USAAF. All theatres together- P51--5944 kills, F6F--5265 kills, P38--3785 kills. Seems pretty clear from a kill point of view. The P38 in ETO had a much worse loss/sortie ratio also than P51.

 

[kool kitty89]

The P-38 was the highest scoring USAAF a/c in the PTO.

 

[Hunter368]

According to my sourcesTO-F6F--5257 kills, F4U--2155 kills, P38--1700 kills, F4F--1408 kills. This has been discussed on other threads, specifically best Pacific fighter and these numbers seem to be authentic. In ETO-P51--4239 kills, P47--2686 kills, P38--497 kills, F6F--8 kills, F4F--2 kills. Med- P38, 1431 kills, P51--1063 kills. I am pretty sure that USN did not give credit for kills on ground, not sure about USAAF. All theatres together- P51--5944 kills, F6F--5265 kills, P38--3785 kills. Seems pretty clear from a kill point of view. The P38 in ETO had a much worse loss/sortie ratio also than P51.

Interesting.

 

[renrich]

There were some kills in the CBI I did not publish if you are wondering why totals don't jibe. It is interesting to look at the data and compare kills versus sorties and how long the AC was operational in a theatre. Another interesting point is to compare kills of fighters versus bombers although the only AC I have that data for is the Hellcat and Corsair. My opinion is that on this forum, because of the almost mythical reputation the P51 has enjoyed in the popular media, our members, in an attempt to bring reality to the views of the P51, have overshot the mark somewhat. In other words, we have denigrated the P51 perhaps in excess of reality. I know I get tired of seeing a TV program that says the P51 was the greatest this that or whatever. Same for books and periodicals. It wasn't the best at every job or in every condition. However, it was a war winner, and an inspired design. It's airframe combined with the Merlin and flown by the intrepid USAAF pilots accomplished some great deeds. I marvel at the thought of those, mostly twenty something, aviators setting out to fly the Mustangs deep into Europe to bring the war to the door steps of the enemy. They truly were a great generation and it was a great aircraft.

 

[Hunter368]

Agreed

 

[Messy1]

I in the end think it always came down to the skills of the pilot flying either one of these planes, both planes are proven designs. both have strengths and weeknesses.
Look at Richard Bong or Thomas McGuire. They knew exactly how to get the most out of their planes, to fight using the strengths the P-38 possesed. There were many P-51 aces who did the same.

 

[kool kitty89]

The only performance advantages the P-51D had over the P-38L at any altitude was roll rate (up to about 300 mph) and diving speed. The P-38, even with dive flaps, was limited to .68 mach the P-51 about .8 mach depending on how close the pilot wants to push it.

 

[drgondog]

According to my sourcesTO-F6F--5257 kills, F4U--2155 kills, P38--1700 kills, F4F--1408 kills. This has been discussed on other threads, specifically best Pacific fighter and these numbers seem to be authentic. In ETO-P51--4239 kills, P47--2686 kills, P38--497 kills, F6F--8 kills, F4F--2 kills. Med- P38, 1431 kills, P51--1063 kills. I am pretty sure that USN did not give credit for kills on ground, not sure about USAAF. All theatres together- P51--5944 kills, F6F--5265 kills, P38--3785 kills. Seems pretty clear from a kill point of view. The P38 in ETO had a much worse loss/sortie ratio also than P51.

I'm still WIP on my final 8th AF ETO (to include 354 and 363FG while they were TDY to 8th AF through 21 June 1944)

The totals I have - dominantly sorting 8th AF VCB with USAF 85 'corrections' (read reductions) and by a/c type..

P-51 = 3328 air 3213 ground plus 350+ from 363 and 354 total air ~3600 air for 8th AF.

P-47 = 1550 air 739 ground

P-38 = 278 air 161 ground.

The 354FG and 363rd continued to score in Mustangs (another 500+) as well as RAF Mustangs (which I don't have) scores. I also don't have the total 9th AF P-47 scores and P-38 scores to round out the ETO

Interesting note in the strafing department. The P-51s scored 5.6 destroyed on ground for every loss strafing, the P-47 scored 3.7 (usually considered more rugged) and the P-38 scored 1.5:1 ratio for highest ratio of strafing LOSSES (all with 2 engines).

There could be a lot of resons for that - namely a lot more 51s roaming the back yards of Germany where in the early days flak defenses may not have been as high as those airfields in P-47 range.. but the 38 got its ass shot off strafing in comparison - and of course this is all about airfield Scores versus losses to ALL kinds of 8th AF strafing so that ratio must be looked at with greain of salt

 

[drgondog]

The only performance advantages the P-51D had over the P-38L at any altitude was roll rate (up to about 300 mph) and diving speed. The P-38, even with dive flaps, was limited to .68 mach the P-51 about .8 mach depending on how close the pilot wants to push it.

You would need to compare the two as closely as possible with focused attention to the loading conditions, the various altitudes at WEP vs MP, to draw judgements like that.. Also, the Flight test versus Factory specs need to be compared.

An example is the P-51H which was tested at NAA (w/o external racks) at 487MPH TAS but the tests by USAAF in 1946 got only 450+ with external racks and combat load of internal fuel and guns ... leaving questions for both results. I have yet to see what the take off gross weight was for the NAA test in Feb 1945

I have yet to see any turning or acceleration comparisons between the two but I would expect the 51 to accelerate slightly less in the 51D and not climb as fast. I would expect the 51 to turn easily with the 38L as the W/L was slightly less, Drag a LOT less, but the 38 had a higher AR to help restore the balance.

Speculating, the two should be very close.

 

[fly boy]

p-51

 

[kool kitty89]

The P-38 also had the high lift airfoil (23000 on inner wings, 4400 outer) and the twin propwash. And don't forget the fowler flaps.

And the chart doesn't show 450+ mph it shows ~440 mph at ~26,500 ft for the P-38L at 1,725 hp WEP.

And I was wrong, the P-51 does have a small top speed advantage between 5,000 and 14,000 ft. (most pronounced at ~11,500 ft where the P-51D has a ~20 mph speed advantage)


And iirc the trials were done with full main tanks with LE wing tanks dry. (300 US gal total)

I don't know the P-51's condition (probably fuse tank empty, 184 gal), but the charts shows a max speed of ~435 mph at 25,000 ft. And an initial climb of ~3,300 ft/min.

 

[drgondog]

The P-38 also had the high lift airfoil (23000 on inner wings, 4400 outer) and the twin propwash. And don't forget the fowler flaps.Interesting, and perhaps important for either landing speeds or lift calculations

And the chart doesn't show 450+ mph it shows ~440 mph at ~26,500 ft for the P-38L at 1,725 hp WEP.

At what loading, amx internal fuel.. and what does the MP and WEP Hp profile look like for all altitudes.. 'sawtooth'??

And I was wrong, the P-51 does have a small top speed advantage between 5,000 and 14,000 ft. (most pronounced at ~11,500 ft where the P-51D has a ~20 mph speed advantage)

A small advantage. the real key is an 'out' manuever' when caught by suprise. Can the P-38L intiallially out turn a pursuing 51D and say, out roll and reverse to attain a superiorior tactical positiion. Can it climb too steeply to enable a 51 to cut the corner and pull deflection?.. in other words what is its 'out manuever' to a a.) escape and b.) reverse a tactical advantage?


And iirc the trials were done with full main tanks with LE wing tanks dry. (300 US gal total).

The 51 trials were done with full internal fuel, oil and full ammo and guns plus external racks

I don't know the P-51's condition (probably fuse tank empty, 184 gal), but the charts shows a max speed of ~435 mph at 25,000 ft. And an initial climb of ~3,300 ft/min.

No, the 51B/C/d and H tests on Mike Williams site were performed with full internal fuel including fuselage tanks.. you need to compare the P-38L at the same tactical load to maintain perspective.. the 3,330 fpm is probably close from Sl area.

 

[kool kitty89]

Thanks for the correction.

But wan't it unsafe to carry much more than a 1/2 full fuse tank due to stability (CoG) problems?

In service, however, the directional instability caused by the presence of a full fuel tank behind the pilot's seat was a hazard for new or inexperienced pilots, and the tank was usually restricted to 65 US gallons. This extra tank, nevertheless, still made a crucial difference in combat radius, and it was standard equipment in all future production versions.

And on the pylons, according to FLYBOYJ, the P-38's pylons were integral to the airframe.


Agree on the load, to compare you'd need figures with the full LE wing tanks. (2x 62 US gal) and the P-51 with the max safe fuel limit. (around 250 US gal) In which condition both would have very similar range.


And on the roll rate, the P-38's boosted ailerons meant roll rate kept increasing as speed increased. In the chart a roll rate of just over 90*/s is shown at 350 mph and ~95 degrees/s at 400 mph.



But another advantage of the P-51 is that it cruised well at high speed, making cruise speeds aproaching 400 mph practical. (and above 400 w/out drop tanks) At ~410 mph the P-51D could still manage almost 800 mi. (granted, with a full fuse tank, so practical closer to 700 mi)
Try that with the P-38 (with 425 gal) and it's down to less than 500 mi at ~380 mph.

as seen here:

 

[FLYBOYJ]

Thanks for the correction.
And on the pylons, according to FLYBOYJ, the P-38's pylons were integral to the airframe.

When did I post that?

 

[drgondog]

Thanks for the correction.

But wan't it unsafe to carry much more than a 1/2 full fuse tank due to stability (CoG) problems?

Yep - but for flight tests at Eglin and Wright Pat, they carried a full combat load at take off. The tests you see on Mike Williams site are pretty explicit about the loads. The aft CG was a serious problem for turns primarily.

I haven't seen the flight plan(s) but a couple of thoughts occur to me. First, if the plan called for high altitude runs I would also be looking for climb to altitude times at MP and other throttle and RPM settings - but just one climb to say 25,000 feet would by itself would burn off 15-20 gallons.

SOP in the field was to reduce the fuse tank 'fill' level to 65 gallons. Most of the guys I talked to like to drain that tank before switching to external tanks which meant forming up and flying to the Dutch or French coast before the tank was fairly well drained - then SOP varied.. but still most like to drain it completely

And on the pylons, according to FLYBOYJ, the P-38's pylons were integral to the airframe.

I did not know that but it wouldn't make a lot of sense to have a non-removable pylon if for no other reason simple maintenance of little things like fuel lines. Photo recon versions of the L for example could perform many of their missions w/O external fuel. I would want the extra 10-20 kts instead.

Agree on the load, to compare you'd need figures with the full LE wing tanks. (2x 62 US gal) and the P-51 with the max safe fuel limit. (around 250 US gal) In which condition both would have very similar range.


And on the roll rate, the P-38's boosted ailerons meant roll rate kept increasing as speed increased. In the chart a roll rate of just over 90*/s is shown at 350 mph and ~95 degrees/s at 400 mph.



But another advantage of the P-51 is that it cruised well at high speed, making cruise speeds aproaching 400 mph practical. (and above 400 w/out drop tanks) At ~410 mph the P-51D could still manage almost 800 mi. (granted, with a full fuse tank, so practical closer to 700 mi)
Try that with the P-38 (with 425 gal) and it's down to less than 500 mi at ~380 mph.

The charts above are the same Lockheed Charts I posted for you several months ago. The thing about them is that we know nothing about the test conditions. I have known Marketing and Sales to occasionally Not disclose everything in test comparisons against a competitor - which is why I tend toward believing Flight Tests with no axe to grind or impression they want conveyed. For example - where did they get the Fw 190 test data? or how was the P-38L loaded relative to internal wing tanks.. take a couple of hundred gallons out and the rolling inertia will be improved.

The post war tests against Fw 190D's for example always leave you wondering how the tests would have been run if say a Focke Wulf factory team with spares and new engines had been pitted against North American and Lockheed and Vought factory reps - and the all the aircraft flown by factory test pilots?

Actually I trust the war time tests more than post war simply because I believe the USAAF, RAF and USN for example - really cared about conveying to the combat operations the strengths and weaknesses of the respective a/c? We can always debate whether the engines were at Spec or the controls properly rigged - but I doubt that the intentions were to 'sell' one aircraft over another in the case of enemy a/c performance.