Selection of Rotor Solidity for Heavy Lift Tiltrotor Design

摘要

The process of rotor blade area sizing during conceptual design was explored for the design of military and civil heavy lift tiltrotors. The use of the comprehensive rotorcraft analysis CAMRAD II was investigated as an aid to aircraft sizing, performed in the RC design code. Hover, cruise, and turn performance calculations were conducted on a initial design from RC with CAMRAD II. The results of this were then fed back into RC and the designs updated. A sustained, level-altitude, 45-deg bank angle, coordinated turn capability at 80 kt was chosen as the critical maneuver condition. This quasi-steady-state condition was modeled in CAMRAD II. Three different ways, appropriate for conceptual design, to quantify the necessary rotor solidity for the maneuver were examined: (1) total power required, (2) a rotor stall boundary as defined by the slope of aircraft power, and (3) a rotor stall boundary defined by the rise in rotor profile power. Stall boundary, defined by a rise in rotor profile power, was identified as the preferred way to select rotor solidity in maneuver. The method developed shows promise as a reasonable approach to accessing rotor solidity requirements during conceptual design.