109 prop pitch (rpm) and the supercharger

[camber]

Thanks robo, that clarifies the story considerably. As I don't have the book I was going on what text was available in this thread and online. It makes sense that the two situations (below FTH and above FTH) are different.

Increasing rpm and supercharger output at high alt will give access to higher boost, in fact the FTH will increase for any particular boost level. But it still seems odd to me that a useful strategy would be to attempt a cycle of rpm pulsing in between maximal power and thrust settings (with the conversion inefficiencies inherent in this). Once you give yourself permission for higher rpm (and boost/power) at height, then it seems more likely that an intermediate constant rpm than the extremes of your pulsing would deliver better performance.

I'm never sure whether doubting a historical pilot assertion is really appropriate from behind a computer in 2012, and Steinhilper could well be right that there was real edge doing the pulsing. However there are many examples of pilots using procedures that the engineers would have frowned upon to give a perceived edge. The edge may have been good for morale but vanishingly small or even a placebo.

My favorite example is the RAF bomber pilots who always turned on their IFF sets over Germany, in the belief that it confused radar operated searchlights. The brass encouraged it in the belief that it improved morale, the scientist RV Jones thought this was totally unacceptable as the IFF sets generated radiations that Germans could exploit for detection sooner or later.