Question

What would an efficient vertical flight mean?

(a) Low power loading

(b) High lift

(c) Less drag

(d) Less pressure difference

The question was posed to me during an interview.

Enquiry is from Helicopter Rotor and Notations in section Helicopter Dynamics of Aerodynamics

Answer 1

The correct choice is (a) Low power loading

To elaborate: In a helicopter, rotor provides thrust force in the vertical direction in order to counter its weight. For an efficient vertical flight, the power loading has to be low which means that the ratio of rotor power required to the rotor thrust should be less. This is achieved by low disk loading i.e. The ratio of rotor thrust to the rotor disk area is minimum.