RPM on a fixed pitched propeller
G'day guys,
Came across this question today and not sure if I have the correct answer.
Anyone shed some light?
Why does an aircraft's RPM, with a fixed pitched propeller, decrease when slowing down and conversely increase when speeding up?
My reasoning is that when the A/C is fast the AoA on the prop is less thus a decreased total reaction on the blade. This leads to a decrease torque on the blade and the engine effectively exerts more force rotating the prop therefore a higher RPM.
(the above might be a complete load of crap)
Care to share insights anyone?