THE AERODYNAMIC INFLUENCES OF ROTOR BLADE AIRFOILS, TWIST, TAPER AND SOLIDITY ON HOVER AND FORWARD FLIGHT PERFORMANCE

The influences of rotor blade planform, twist, and airfoils on hover and forward flight performance are reviewed. Although the design philosophy described can be considered to be general in nature, the analysis presented is related to a UH-1 type helicopter. The results show that the radial position of the initiation of taper and taper ratio can have a significant influence on the efficiency of a rotor in both hover and forward flight. The influence of these two parameters decreases as blade solidity is increased. The influence of linear twist varies with location of taper initiation and taper ratio. It is observed that the blade planform, twist, and airfoils should be considered simultaneously on the basis of the lift coefficient-Mach number requirements for a given configuration. Design considerations such as autorotation characteristics and aircraft maneuvers must be considered also but are not addressed herein. However, the latter can be considered within the same context as the forward flight lift coefficient-Mach number operating conditions.