Power required for helicopter climb and descent along an inclined trajectory

Answer 1. The power required for climb and descent consists of three parts: the power required to overcome profile drag, for horizontal motion of

the helicopter, and for vertical motion of the helicopter.

Daring constant-velocity flight the profile power remains the same in all regimes. The power required for horizontal displacement also remains constant both for horizontal flight and for climb and descent. The power expended on vertical displacement will be more during climb, and less during descent. The sum of all these parts, i. e., the power for the given regime, will be practi­cally the same in all regimes and varies with variation of the flight speed.

Answer 2. The power required for climb and descent along an inclined trajectory consists of three parts: the power required to overcome the profile

drag; the power to create the lift force equal to the helicopter weight; and the power to overcome helicopter parasite drag.

During flight at constant speed the profile power remains constant in all regimes. The power required to create the lift force during climb will be more, and during descent will be less than in horizontal flight. If the velocity is unchanged, then the power required to overcome the parasite drag will remain unchanged. Consequently, the power required for climb is more than that for horizontal flight, while the power required for descent is less.

Answer 3. The power required for climb and descent along an inclined trajectory consists of three parts: the power required to overcome the profile

drag, the power for creating the lift force, and that for motion of the helicopter along the given trajectory.

The profile power remains practically unchanged if the main rotor rpm remains the same in the various flight regimes. During climb and descent (climb and descent angles no more than 10°) the induced power remains unchanged and practically equal to the induced power for horizontal flight. The power required for motion during climb is more than the power required for motion in /114 horizontal flight by the magnitude of the excess power AN, i. e., N ^ = N^ + AN, and the power required for motion during descent is less than the power required for horizontal flight by the amount AN.