Thanks for having a stab at this Achimha and Heston
I've clicked around so many internet sites trying to work it out, my mouse is about to go into meltdown... (other things, too....)
The airplane takes a certain amount of power (lost as drag) - compare that to the power output of the engine.
That sounds like a cunning plan.....
But I can't, can I? I mean, drag being in Newts and power output being in Watts?
I thnk the numbers are ok, but something might have been lost in translation. The original question, just in case this helps, is:
Un avion vole à 65m/s. Sa traînée est de 4,22 kN avec une puissance fournie de 36Kw. Calculer le rendement de l'hélice?