PPRuNe Forums - View Single Post - Turbojet - Thrust-producer /// Piston-prop - Power-producer
Old 17th Mar 2013, 14:49
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Romeo Kilo
 
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As a classmate of d2180s, add like to add to his question...

Within the context of climb performance, we have been shown the differences in terms of best angle/rate of climb with respect to thrust - a force; and power - rate of doing work, or indeed a force exerted over a distance per unit time.

It makes sense to me that, looking at range for example, whilst a speed that offers us minimum drag sounds efficient, we may able to travel further by sacrificing some drag in favour of true airspeed. So all of a sudden time is a factor, and we care about power rather than work, and speed rather than distance. Cool. I guess there's some sort of calculus going on there.

Why, however, is it that the best angle of climb in a propeller aircraft is derived from minimum power rather than minimum drag? When considering angle of climb, we think of it as a simple triangle, purely based on altitude/height gained per distance covered, which, at least in a jet engined aircraft, is directly linked to the geometry of the forces acting upon the aircraft. Why then, for a propeller aircraft, when we are not interested in the time taken to reach a certain height, only the distance covered, does power play a role?

I think that, essentially is what I'd like to add to d2180s's question. Its all very well being able to regurgitate the giff in the exam, but I get the impression this is some 'need to know' stuff. Pilot Sh!t, if you will.

Thanks for any help
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