Yesterday, 14:15
it's a long time ago now (1950's) but my fathers Proctor, during run up he would set the throttle to full, with the Prop set to coarse, watch the Boost gauge, then push the prop lever to Fine watch the RPM go from about 1700 at coarse to 2400 at fine. If one then closed the throttle the RPM would decrease to idle ( noise with it) . In flight running flat out level flight 2400 RPM indicated, Boost - 1/2 psi, about 160/170 mph, if one pulled the prop lever fully back to coarse the RPM would drop back to about 1700 (too low for continuous running as oil pressure insufficient for bearings & possibly prop angle change) noise would drop, but airspeed & rpm should increase until a balance of HP, & drag in theory should equalise. My FS9 Proctor uses a Gypsy Major & fixed pitch set of sounds made...