karnak

[Nashwan]

The USAAC/USAAF never officially authorized it.

So the performance figures you wuoted are only from Lockheed tests, not official USAAF ones?

The fuel issues were a problem in England, but not elsewhere for the most part. Fuel in England was so bad that Doolittle had to go to his peacetime employer Shell to get decent fuel.

Never seemed to affect other aircraft.

But the question about 100/150 or 115/145 remains. Did the increased 1725 hp rating require it? (100/150 and 115/145 are not simply "better quality" fuel, they have higher octane ratings than the standard 100/130)

[Captain Virgil Hilts]

Originally posted by Nashwan
So the performance figures you wuoted are only from Lockheed tests, not official USAAF ones?

The USAAF may or may not have tested the P-38 at those settings. The fact remains, Lockheed tested the plane at those settings, and certified it. GM/Allison tested the engines at those settings, and certified it. The USAAC/USAAF saw the tests, saw the results, and was aware it could be done. Further, units in the field used the settings.

Never seemed to affect other aircraft.

[/B]

Oh, but it did. P-51's had the same problems, fouled plugs, detonation, hammered rod bearings, cracked heads, blown head gaskets, and a host of others. The early return percentage for the P-51 at the time was as high or nearly as high as that of the P-38. Further, the P-38 was in fact being flown at the wrong settings for RPM and MAP, and was not being properly maintained, both problems due to a failure of the 8th AF to get the correct information to the pilots and the crews. THAT was the main reason the USAAC/USAAF did not officially aprrove the higher power settings.

Below find Tony Levier's report on the ETO and their problems, it is a direct verbatim copy of his report as it appears in Lockheed's files:


Report on P-38s in the ETO, by Tony Levier.

“Having just returned from a four month mission to England on 29 May 1944 where I had been testing and demonstrating some of the new improvements on our P-38J’s, I filed the following report:”

Immediately upon arriving in England, I proceeded to the 55th FG HQ at Nuthamstead, an airbase in East Anglia, north of London, where conditions were pretty grim as far as their P-38’s were concerned. They had just received their first P-38J’s, and had no operational information on them. Their lack of information concerning correct power combinations was appalling.

For combat missions some pilots were using anywhere from 2000RPM to 3000RPM with whatever manifold pressure that would giver them their desired air speed. Some of these pilots were blowing up their engines with high manifold pressure and critically low RPM, while others were running out of gas and failing to complete missions because of such power combinations for continual cruise at 2800RPM with 24” of manifold pressure. Many returned with hardly more than a cupful of gas remaining in their tanks, while others were forced to bail out over enemy territory.

The reason they were cruising at 2600, 2800 and even 3000RPM was that somewhere along the line they had been taught to use high RPM and low manifold pressure. They were under the impression that should they get jumped by a Jerry they could get their power faster if they already had their engines running at high RPM.

The fact is you can get your power quicker if you have low RPM and high boost which gives you a high er turbosupercharger speed. With turbochargers putting out high boost you only have to increase your engine RPM to get your desired power.

Rather than add to their confusion with power curves and range charts we devised the following rule of thumb for their long range missions. It is simple and easy to remember and insures maximum engine efficiency/fuel economy: USE 2300RPM AND 36” MANIFOLD PRESSURE AS THE MAXIMUM FOR AUTO LEAN AND CRUISE CONDITIONS. IN REDUCING POWER FROM THIS SETTING, REDUCE ˝” TO 1” FOR EACH 100RPM; FOR GOING ABOVE THIS SETTING PUT YOUR MIXTURE IN AUTO RICH AND INCREASE THE MANIFOLD PRESSURE 2” FOR EACH 100RPM.   

After using this rule the boys marveled at their increased range. Some were returning from 4 hour missions with as much as 150 to 200 gallons of fuel left. Quite a bit more than the cupfuls they had been returning with.

The day after I arrived at another base in England some P-38 pilots who had been escorting Forts over mainland Europe reported a “sort of engine trouble”.

When pinned down they said their engines had been surging and momentarily cutting out while they were flying at altitude under reduced power. The passed it off saying, “it’s probably caused by some extra low octane gas.”

But after further discussion with the boys I suddenly remembered a series of tests we had run back home during flight test operations for proper turbosupercharger settings. As I recalled, the symptoms were very similar.

So I obtained permission from the 55th FG CO to test a P-38 at altitude for proper turbosupercharger operation, and sure enough, the turbosupercharger on the left engine was so rigged that the resulting backpressure and high turbosupercharger wheel speed caused the airflow to the engine to surge, resulting in erratic operation and inability to pull power.

Upon landing, I reported the trouble and recommended that each Lightning driver be given the following procedure for checking his ’38 at altitude for proper turbosupercharger operation: At 30K feet set your RPM at 2600RPM and 37” manifold pressure and back off slowly on the power down to 10 to 15” manifold pressure. While doing this, fix your eyes on the manifold pressure and note if there is the slightest engine failure or surging. Record the exact manifold pressure at which this surging occurs.

Now repeat the process beginning with 2300RPM and 37” manifold pressure , and again record the boost at which surging occurs. (At this lower RPM it should occur 2 or 3” higher.)

If, after you’ve completed this procedure, either of the recorded manifold pressures are above 22”, it indicated the turbosupercharger regulator is set improperly. Tell your mechanic the boost at which the roughness occurred and he will make the necessary adjustments.
 


The above mentioned problems are why the P-38 supposedly "seemed" to have problems other planes did not. It was not the fault of the plane, or the engines, but rather that it was not being properly flown and maintained, not due to the pilots and crews, but due to them not being properly informed.

But the question about 100/150 or 115/145 remains. Did the increased 1725 hp rating require it? (100/150 and 115/145 are not simply "better quality" fuel, they have higher octane ratings than the standard 100/130)

Flown at the proper settings, and with the better quality fuel available after Doolittle got Shell involved, the L model could use the maximum power settings as proscribed by Lockheed and GM/Allison

[Widewing]

Originally posted by Karnak



The P-38 as described by Captain Virgil Hilts (derived from reading his posts on the subject):

450+mph
4,500fpm+ climb
no compression issue (myth made up by a corrupt congressional comitee)
Rolls faster than an Fw190
Turns better than a Spitfire Mk V
Longer ranged than a P-51D
More durable than an Il-2
Easier to fly than an A6M2
100% viceless and impossible to stall (twin engines will do that you know)

A few historical facts supported by both documentation and the word of the men who flew both the P-38 and P-51 in combat:

1) When employing the full rating authorized by Allison (1,725 hp), the P-38L was able to pull 440 mph at critical altitude. The USAAF de-rated the engines to 1,600 hp for increased reliability. Nonetheless, Allison tech reps assisted crew chiefs in rigging for full power rating.

2) Climb rate with 1,725 hp per engine was in the range of 4,300 to 4,600 fpm depending upon fuel load.

3) Compression was always an issue. The dive recovery flaps made compression managable, but did not change its nature. If you didn't deploy the flaps, they were of no value.

4) Above 325 mph, the P-38J-25-LO and all P-38Ls did have a faster sustained rate of roll than the Fw 190. Inertia did have an effect on initial roll rate. But, once rolling, late P-38s were the fastest rolling fighters of the war above 350 mph (thanks to hydraulic boosting of the ailerons, full deflection was possible at very high speeds).

5) P-38s could not out-turn Spitfire Mk.Vs. They didn't need to. Their acceleration and vertical capability offset the Spit's low-speed agility.

6) With 310 gallon drop tanks, the P-38 did out-range the P-51D. However, this required a cruise speed substantially lower than that of the P-51D.

7) With twin engines, the P-38 had a built in safety factor unmatched by any single-engine aircraft. IL-2s were heavily armored to resist ground fire. They were not well protected against air to air fire from the rear quarters. Yet, airframe durability favors the IL-2 because of its simple and robust  construction with few vital systems to be damaged.

8) P-38s were complex aircraft requiring extensive training to master. It was not easy to fly.

9) Stall characteristics of the P-38 were far more gentle than any other American fighter.

My regards,

Widewing