Bill, you're mostly right. I've done a little research, and the answer is both the demand for Merlins for the P-51D, and also a warning from NACA that fitting them in a P-38 would be dangerous because the critical speed for the 38's fat wing (containing fuel tanks) is 450 mph. Any more than this will run into compressability problems, so the extra power from a Merlin or Griffon couldn't be used. The Brits had started design drawings to convert their Lend-lease 38s, supplied by the US without contra-rotating engines or turbochargers, and therefore useless, with one of these engines, desisted when the NACA report came in.
The following is lengthy, but anyone interested in WWII aircraft in combat will find it fascinating:
20th Fighter Group Headquarters
APO 637 U.S. Army
(E-2)
3 June 1944
Subject: P-38 Airplane in Combat.
To: Commanding General, VIII Fighter Command, APO 637, U.S. Army.
1. The following observations are being put in writing by the undersigned at the request of the Commanding General, VII FC. They are intended purely as constructive criticism and are not intended in any way to "low rate" our present equipment.
2. After flying the P-38 for a little over one hundred hours on combat missions it is my belief that the airplane, as it stands now, is too complicated for the 'average' pilot. I want to put strong emphasis on the word 'average,' taking full consideration just how little combat training our pilots have before going on as operational status.
3. Let us assume that we have a pilot fresh out of flying school with about a total of twenty-five hours in a P-38, starting out on a combat mission. He is on a deep ramrod, penetration and target support to maximum endurance. He is cruising along with his power set at maximum economy. He is pulling 31" Hg and 2100 RPM. He is using auto lean mixture and running on external tanks. His gun heater is off to relieve the load on his generator, which frequently gives out under heavy load. His sight is off to save burning out the bulb. His combat switch may or may not be on.
Flying along in this condition, he suddenly gets "bounced", what to do flashes through his mind. He must turn, he must increase power and get rid of those external tanks and get on his main. So, he reaches down and turns two stiff, difficult gas valves to main, turns on his drop tank switches, presses his release button, puts the mixture to auto rich (two separate and clumsy operations), increases his RPM, increases his manifold pressure, turns on his gun heater switch (which he must feel for and cannot possibly see), turns on his combat switch and he is ready to fight.
At this point, he has probably been shot down or he has done one of several things wrong. Most common error is to push the throttles wide open before increasing RPM. This causes detonation and subsequent engine failure. Or, he forgets to switch back to auto rich, and gets excessive cylinder head temperature with subsequent engine failure.
4. In my limited experience with a P-38 group, we have lost as least four (4) pilots, who when bounced, took no immediate evasive action. The logical assumption is that they were so busy in the cockpit, trying to get organized that they were shot down before they could get going. [Nick's Note: Maybe this is the way the great multi-ace MacGuire was finally shot down.]
5. The question that arises is, what are you going to do about it? It is standard procedure for the group leader to call, five minutes before R/V and tell all the pilots to "prepare for trouble". This is the signal for everyone to get into auto rich, turn drop tank switches on, gun heaters on, combat and sight switches on and to increase RPM and manifold pressure to maximum cruise. This procedure, however, does not help the pilot who is bounced on the way in and who is trying to conserve his gasoline and equipment for the escort job ahead.
6. What is the answer to these difficulties? During the past several weeks we have been visited at this station time and time again by Lockheed representatives, Allison representatives and high ranking Army personnel connected with these two companies. They all ask about our troubles and then proceed to tell us about the marvelous mechanisms that they have devised to overcome these troubles that the Air Force has turned down as "unnecessary". Chief among these is a unit power control, incorporating an automatic manifold pressure regulator, which will control power, RPM and mixture by use of a single lever. It is obvious that there is a crying need for a device like that in combat. [Nick's Note: The engine-management system the Colonel says is necessary was fitted in Griffon Spits.]
7. It is easy to understand why test pilots, who have never been in combat, cannot readily appreciate what each split second means when a "bounce" occurs. Every last motion when you get bounced is just another nail in your coffin. Any device which would eliminate them are obviously very necessary to make the P-38 a really effective combat airplane.
8. It is also felt that that much could done to simplify the gas switching system in this airplane. The valve selector handles are all in awkward positions and extremely hard to turn. The toggle switches for outboard tanks are almost impossible to operate with gloves on.
9. My personal feeling about this airplane is that it is a fine piece of equipment, and if properly handled, takes a back seat for nothing that the enemy can produce. But it does need simplifying to bring it within the capabilities of the 'average' pilot. I believe that pilots like Colonel Ben Kelsey and Colonel Cass Huff are among the finest pilots in the world today. But I also believe that it is difficult for men like them to place their thinking and ability on the level of a youngster with a bare 25 hours in the airplane, going into his first combat. That is the sort of thinking that will have to be done, in my opinion, to make the P-38 a first-class all around fighting airplane.
HAROLD J. RAU
Colonel, Air Corps,
Commanding.
Captain Stan Richardson of the 55th Fighter Group recalls some of his experiences as an instructor at a stateside RTU.
All the combat instructors who gained their experience in Africa or in the Pacific, had done the vast majority of their combat flying below 20,000 feet. Therefore, new pilots were trained to fly the P-38 at altitudes below that height. Very few pilots had flown the Lightning at the altitudes required by 8th Air Force mission profiles and were loath to do so. Many of the P-38 trained pilots arriving in Britain requested assignment to the 9th Air Force in order to fly at lower levels where they had both experience and confidence in the ability of the airplane to do the job. Nonetheless, the high priority given to providing escort fighters determined that nearly all the incoming pilots were destined for the 8th. Most P-38 pilots were completely unprepared for high altitude operations nor the technical problems involved.
"These new pilots made their attempts to go to altitude, but those early airplanes, the way they were set up, just wouldn't make it. There were disastrous incidents of ignition breakdown because of high-tension leakage. The oxygen systems were woefully inadequate. This is what they put into the airplane and the pilot in the cockpit was stuck with what he had. It just wouldn't do the job. No one liked 30,000 feet anyway. There had been no training for it. There had never been any need for it. It was too cold and the windows frosted up."
"All this piled up on the 8th Air Force pilots, but there they were at 30,000 feet plus and sixty below zero. It was miserable."
"Then things really started to come apart. Now, suddenly, turbochargers were running away. They were blowing up engines on the basis of one engine blow up every seven hours. Intercoolers were separating the lead from the fuel and the result was lowered octane. Hands and feet were freezing; pilots were calling their airplanes airborne ice wagons and they were right. Frost on the windows got thicker than ever. Most disgusting of all was the leisurely way the German fighters made their get-aways straight down."
"Another problem was the single generator. With a lost generator or a low battery the Curtis Electric prop would lose the Dynamic Brake and go to extreme Low Pitch. This was called a RUN AWAY. It could happen on Take Off with a low battery. Since you couldn't feather it set up a lot of drag making it difficult to make it around to land. The Killer situation was to lose the Generator or lose the engine with the Generator on it while 2 or 3hrs into Germany. Procedure was to SET the Props then turn off all electrical power. Then momentarily turn it back on to reset the props as needed. Being sure everything electrical was also turned off -- No Radios. The forgotten thing was you were at altitude and the OAT was -60degrees and the little old battery was cold soaked and dead. Result, with a lot of altitude you have less than an hour's flight with one or two props in RUNAWAY.
I believe that more P-38s were lost from this than any other factor including combat. This simple problem did not receive attention until April, '44."
"My only experience in these problems, was of course the runaway prop, and once when the boost pump circuit breakers popped while we were engaged with some 109s. So there I was holding in the circuit breakers with my right hand while flying with my left, hoping to get to a lower altitude before something burned up." [Nick's Note: The altitude and extreme cold problems, for man and machine, didn't exist in the Pacific Theater, only in Europe. Good old American Knowhow got to work and solved all these problems eventually, and P-38 turned into a good aircraft. Good enough for the Germans to call it Der Gabelschwantz Teufel - forked-tail devil.
Based on Nick's review-I'll order it....
