Shortround6
Major General
I would note that the article makes several mistakes that we have mentioned before.
1.
" Arrival of the newer P-38J to fill in behind the P-38H was supposed to help, but did not help enough. The J model's enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison's induction system at extreme low temperatures. This could cause detonation and rapid engine failure, especially at the high power settings demanded for combat."
I have no idea if some of the fuel causing problems was blended in Britain or In British controlled refineries but at this point the US and the British were using a common fuel specification/s and had been for some sometime. This specification (for 100/130 fuel) had been changed 3 times (at least) and the changes were known to the parties (using air air forces and engine makers, in addition to the oil companies) involved. Allowable lead for instance had gone from 3.0cc per US gallon to 4.0cc per US gallon to 4.6 cc Per US gallon. This allowed for much higher production of 100/130 from base stocks without building additional refining capacity. The Problem the P-38s were having was NOT with the lead coming out of the fuel. Other changes in the fuel specification allowed for a higher use of aromatic compounds which do raise the knock limit, these are heavier than straight run gas and have different vapor points and freezing points. The effect of using these compounds (which are NOT lead) was suspected or known months before the P-38J showed up in Europe and Allison had been working on a new intake manifold to help combat the problems since the spring of 1943. It took until near the end of 1943 to get the Manifold in to service (and manifolds were shipped overseas for refitting to existing engines). I believe that Allison began fitting the new manifold to ALL Allison engines, not just P-38 engines shortly after.
2.
"In an article on ausairpower.net, Carlo Kopp noted that in their early days in the European theater, "Many of the P-38s assigned to escort missions were forced to abort and return to base. Most of the aborts were related to engines coming apart in flight….[due to] intercoolers that chilled the fuel/air mixture too much. Radiators that lowered engine temps below normal operating minimums. Oil coolers that could congeal the oil to sludge. These problems could have been fixed at the squadron level. Yet, they were not."
A partial fix was ready to hand, simply operate the P-38 according to Allison and Lockheed instructions. Instead the Army thought they knew better. They operated at a high cruise RPM and low boost. This kept the intake air cool or cold and really didn't work the engine very hard (part throttle at high rpm). Allison and Lockheed were recommending low rpm and high boost (greater use of the turbo when cruising) which would have heated the air more before it went through the intercooler and would have meant hotter air going though the engine supercharger and into the manifolds helping stop the the fuel separation and fuel puddling in the manifolds. Hotter air going in raises the temperature of the gases all the way through the engine, hotter combustion chamber temperature and hotter exhaust temperature. This may not have fixed the oil temp problem but it sure couldn't hurt. The Army gave in and began operating the P-38 the way Allison and Lockheed wanted but not until the late spring/summer of 1944. This was in conjunction with a visit by Tony Levier (Lockheed test pilot) to P-38 units in England.
Operating an aircraft against both the airframe and engine makers recommendations and then blaming the aircraft doesn't seem quite fair. The low RPM and high boost technique was hardly new or novel. The British had been doing it with non-turbo planes for several years before the P-38 showed up in late 1943.
It also helps with the turbo spool up problem as the turbo is operating at a higher speed when cruising than the high engine rpm/low boost method of cruising.
Yes you need for the engine and props to accelerate up to speed but the props should automatically adjust pitch to the power going to them. Trying to go from high cruise engine rpm to combat power with the turbo trying to go from just off idle to full boost is going to leave you with turbo lag (engine starving for air) while an engine at lower rpm but with full (or nearly full) boost from the turbo will actually make more power at the lower rpm and then build.
1.
" Arrival of the newer P-38J to fill in behind the P-38H was supposed to help, but did not help enough. The J model's enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison's induction system at extreme low temperatures. This could cause detonation and rapid engine failure, especially at the high power settings demanded for combat."
I have no idea if some of the fuel causing problems was blended in Britain or In British controlled refineries but at this point the US and the British were using a common fuel specification/s and had been for some sometime. This specification (for 100/130 fuel) had been changed 3 times (at least) and the changes were known to the parties (using air air forces and engine makers, in addition to the oil companies) involved. Allowable lead for instance had gone from 3.0cc per US gallon to 4.0cc per US gallon to 4.6 cc Per US gallon. This allowed for much higher production of 100/130 from base stocks without building additional refining capacity. The Problem the P-38s were having was NOT with the lead coming out of the fuel. Other changes in the fuel specification allowed for a higher use of aromatic compounds which do raise the knock limit, these are heavier than straight run gas and have different vapor points and freezing points. The effect of using these compounds (which are NOT lead) was suspected or known months before the P-38J showed up in Europe and Allison had been working on a new intake manifold to help combat the problems since the spring of 1943. It took until near the end of 1943 to get the Manifold in to service (and manifolds were shipped overseas for refitting to existing engines). I believe that Allison began fitting the new manifold to ALL Allison engines, not just P-38 engines shortly after.
2.
"In an article on ausairpower.net, Carlo Kopp noted that in their early days in the European theater, "Many of the P-38s assigned to escort missions were forced to abort and return to base. Most of the aborts were related to engines coming apart in flight….[due to] intercoolers that chilled the fuel/air mixture too much. Radiators that lowered engine temps below normal operating minimums. Oil coolers that could congeal the oil to sludge. These problems could have been fixed at the squadron level. Yet, they were not."
A partial fix was ready to hand, simply operate the P-38 according to Allison and Lockheed instructions. Instead the Army thought they knew better. They operated at a high cruise RPM and low boost. This kept the intake air cool or cold and really didn't work the engine very hard (part throttle at high rpm). Allison and Lockheed were recommending low rpm and high boost (greater use of the turbo when cruising) which would have heated the air more before it went through the intercooler and would have meant hotter air going though the engine supercharger and into the manifolds helping stop the the fuel separation and fuel puddling in the manifolds. Hotter air going in raises the temperature of the gases all the way through the engine, hotter combustion chamber temperature and hotter exhaust temperature. This may not have fixed the oil temp problem but it sure couldn't hurt. The Army gave in and began operating the P-38 the way Allison and Lockheed wanted but not until the late spring/summer of 1944. This was in conjunction with a visit by Tony Levier (Lockheed test pilot) to P-38 units in England.
Operating an aircraft against both the airframe and engine makers recommendations and then blaming the aircraft doesn't seem quite fair. The low RPM and high boost technique was hardly new or novel. The British had been doing it with non-turbo planes for several years before the P-38 showed up in late 1943.
It also helps with the turbo spool up problem as the turbo is operating at a higher speed when cruising than the high engine rpm/low boost method of cruising.
Yes you need for the engine and props to accelerate up to speed but the props should automatically adjust pitch to the power going to them. Trying to go from high cruise engine rpm to combat power with the turbo trying to go from just off idle to full boost is going to leave you with turbo lag (engine starving for air) while an engine at lower rpm but with full (or nearly full) boost from the turbo will actually make more power at the lower rpm and then build.