ok, here is my attempt to simplify the whole thing for my students.
Rotor profile drag/power - power required to run the rotor systems at normal operating speed while sitting on the ground with the lever fully down, this includes air resistance on the blades leading edges and all transmission and ancillaries drag from engine to final drives. in a robinson this accounts for 13-14" manifold pressure, in a 206 as i recall it was 15-20% torque (i cants actually remember this figure), rotor profile drag is generally constant over the speed range but the increase in drag on the advancing blade increases more than the decrease in drag on the retreating blade, so overall there is a small increase.
Induced Drag/Power - drag created by raising the lever and forcing air down through the rotor disc to create lift. sitting on the ground this will be theoretically nil with the lever down.
it will be at its maximum in the hover with no ground effect and induced drag reduces with an increase in airspeed
Parasite drag/power - drag of airframe through the air (excluding rotor blades as they are included in rotor profile drag),this increases exponentially in a similar way to cars as airspeed increases
add all these values together and you get the "u" shaped power curve we are familar with.
comments all this lot please !
as i assume nobody will agree with it.
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elpirata