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Shortround6:
This last post is very enlightening and gets to the core of the initial question.
Shortround6:
Speaking of German superchargers, which wasn't included in the scope of the original question, can you provide any insight as to how they kept pace with Hooker's developments of the Merlin?
The shortcomings of the Allison supercharger were:
a/ it was too small. Its diameter was only 9.5 ins compared to the 10.25 of the Merlin. When Hooker analysed the R-R supercharger, he quickly found that it was strangling the engine. If this was the case with the R-R product, then the Allison must have been really suffering as evidenced by the huge amount of trouble the P-40 engines had with detonation.
b/ it was mounted too close to the back of the engine. Drawings of the V-1710 s/c clearly show the very tight angle between the outlet of the s/c and the start of the inlet manifold.
c/ the V-1710 induction manifold was extremely convoluted. This posed problems for the mixture flow as evidenced by the necessity to provide special pickups for raw fuel that gathered at the base of the main inlet branch.
d/ development of the V-1710 s/c was, for a long time, not given much attention because it was felt that the turbocharger would provide the main source of supercharging for all US aero-engines.
Neither. The Merlin was in production for about three years before the Allison. There was far more time to sort out technical, production, training, and operational issues.It seems to me, that the biggest difference between Rolls Royce and Allison, is in how quickly one adapted to the needs of war, and how one didn't. Was it because Alison was a General Motors company, or was it because the American Army technical staff were mind boggling incompetent?