If we had an airplane engine turning a fixed-pitch propeller
and equipped with both a tachometer and a manifold pressure gauge, each instrument's values would fall when reducing power from full throttle.
The R7 Ranger is different from many LSAs because it has an all-aluminum fuselage and interestingly, a 100-HP Continental O-200-D spinning a Catto fixed-pitch propeller
. Where lots of other LSA models are powered by some kind of Rotax, Torode decided that the R7 had to have a small Continental even if means a weight penalty because he thinks it's iconic, easily serviced in the field and would be more accepted by flight schools and also older pilots.
As engine horsepower increased post World War I, the wooden fixed-pitch propeller
that operated efficiently only at its design speed was no longer enough.
The pivoting nacelle incorporates a large electric AC motor directly driving a fixed-pitch propeller
. The motor is speed-controlled by a frequency converter, with full torque available in either direction from zero to nominal speed.
The aforementioned fixed-pitch propeller
is a single piece of aluminum alloy or wood.
Even relatively simple airplanes, those with welded-down landing gear and a fixed-pitch propeller
, can have complicated systems.
For example, the diameter of a fixed-pitch propeller
is often large to favor low airspeed operation, while the blade size is small to favor higher airspeeds and faster turning at low airspeeds.
During Part 23 certification of general aviation and commuter aircraft, glide performance must be determined and AC 23-8C specifies that for a fixed-pitch propeller
, "stalling the airplane to stop the propeller from windmilling is not an acceptable method of determining performance because the procedure could cause the average pilot to divert attention away from the primary flight task of gliding to a safe landing." Indeed.
Check your airplane's Pilot's Operating Handbook (POH) for specific guidance but, in general, fixed-pitch propeller
engines need to be leaned for maximum propeller speed at full throttle.