i have some questions to ask on some questions
1) on an aircraft with a fix ptich propeller , with power constant , and if the nose is lowered and speed increase , the angle of attach of blade a) increase b)decrease c) remain the same
2) a constant rpm on the ground with a fix pitch propeller , the effect of a headwind willa) increase or b)decrease the rpm
thanks
Hi Dennis,
1) As you increase speed, the angle of attack on the blade decreases. The reduced angle of attack means there will be less thrust and less torque ("propeller drag") produced. Less toque means the prop becomes easier to turn and so, for a constant power setting, the RPM will increase.
2) Same principle applies. A 10kt headwind is aerodynamically equivalent to moving at 10kt in no wind. Therefore the headwind will result in a higher RPM.
Cheers,
Rich
