As I understand it, adjusting RPM will affect fuel consumption, although I think the effect is minor. (You can easily see the effects of RPM and MP on thrust.)
From the P-51 writeup:
Emergency Power- 67" @ 3000 RPM, 210 GPH
Military Power- 61" @ 3000 RPM, 150 GPH
Normal Power- 46" @ 2700 RPM, 86 GPH
Max Cruise- 36" @ 2400 RPM, 71 GPH
I have a NACA report (number 749) that found only a small (less than 5 percent) increase in range using a variable pitch prop instead of fixed pitch. Not sure what the effect is in AH.
popeye
