Originally posted by Kurfürst
No, I suggested that 150 grade was appearantly more problematic and less widespread than the 'unversal' use that Neil suggests. It took time to try to solve problems, evidently the USAAF Merlins had problems that weren't sorted out until the end of the war, so I wonder how much use it saw, really. Of course some used it, but let us remember that Neil and others told the story as like from spring 1944 virtually every figther unit made used of the increased performance, but the more and more we see of the documentation the more this view becomes wishful thinking and more grey rather than black and white. It would be really nice to know the real extent of the use, but I fear there is no willingness on the behalf of Neil to show the real facts, rather than the all-positive, filtered ones.
100/150 was used by
all 8th AF fighter groups, and it was used up until VE day. After VE day, all units went back to 100/130 as there was sufficient volumes of that fuel to meet the reduced flying requirements. Some units requested stocks of 100/130 when engine maintenance was severely affected by the newly introduced "PEP" additive (March '45), but this did not occur until late March/early April and the lower octane rated fuel was not generally available to the 8th FC.
Looking at the 56th FG, I cannot find any references of valve seat damage to the R-2800 from the use of 100/150 with PEP. It may be that this engine was not as susceptible to this problem or that there was insufficient data from its limited use (over 3 months) and limited P-47M sorties. I do know that the R-2800 C-series was dyno tested at 80" MAP for 250 hours using 100/130 and suffered no mechanical failures. So, I'd be inclined to think that the P-47M would have benefited as much from rigging for over-boost as it would have from 100/150. It appears that the PEP additive was coming out of solution (separating) in the intake manifold of the Merlin. This is a problem similar to that experienced by the Allisons used in P-38Js in early 1944. A special fuel formulation was ordered by Doolittle specifically for P-38 units that solved this problem (which was further addressed by a design change to the manifolds). Solution breakdown did not occur in the R-2800 engine, which could run with good efficency and reliability on just about any fuel available.
By the way, usage can be clearly defined by month to month deliveries. When I get a delivery of home heating oil, I get a receipt that not only defines what was delivered, but what was replaced due to consumption.
So, any argument that there is no record of fuel consumption would be imbecilic, and to argue that there was no usage of massive stores of 100/150 stretches credibility to the breaking point. Indeed, Freeman states that 100/130 was not generally available to the 8th Fighter Command; "as the old grade had been largely replaced by 100/150, supply was difficult."
My regards,
Widewing
