Originally Posted by +'ve ROC
EXACTLY what I'm after Halfbaked_Boy
Am I correct in saying that the pitch of a single blade prop would be 'fatter' to counter the fact that there is only one of them?
Cheers
Chris
Not necessarily - because the best efficiency occurs when the angle of attack of an aerofoil is the one giving the best thrust/drag ratio - which is about 4 degrees for most (duly noting that angle of attack isn't the same as blade pitch due to the induced airflow reducing the A of A).
A single blade would need to be longer for best efficiency (like a long glider wing) - which would give ground clearance and tip speed problems, wider chord would be less efficient.... everything is a design compromise.
Multiple blades work well where the angle of attack can be kept close to the optimum thrust/drag ratio but too many blades are badly affected by the wake of the previous blade, reducing efficiency.