Rotor head for helicopter - has coaxial counter-rotating sets of blades of different lengths to reduce deflection

摘要

A helicopter has two co-axial rotors rotating in opposite directions in order to cancel the driving torque and so eliminate the need for a tail rotor. In order to reduce the height of the rotor head the blades (P1) of the upper rotor are shorter than the blades (SP2) of the lower rotor. With these shorter blades there is less deflection and so there is no risk of contact between the upper and lower blades with a compact rotor head. In addition the aerodynamic interference between the rotors is reduced with a consequent increase in efficiency of propulsion.