Impact of Aerodynamics and Structures Technology on Heavy Lift Tiltrotors

摘要

Rotor performance and aeroelastic stability are presented for a 124,000-lb large civil tilt rotor (LCTR) design. It was designed to carry 120 passengers for 1200 nm, with performance of 350 kt at 30,000-ft altitude. Design features include a low-mounted wing and hingeless rotors, with a very low cruise tip speed of 350 ft/s. The rotor and wing design processes are described, including rotor optimization methods and wing/rotor aeroelastic stability analyses. New rotor airfoils were designed specifically for the LCTR; the resulting performance improvements are compared to current technology airfoils. Twist, taper, and precone optimization are presented, along with the effects of blade flexibility on performance. A new wing airfoil was designed, and a composite structure was developed to meet the wing load requirements for certification. Predictions of aeroelastic stability are presented for the optimized rotor and wing, along with summaries of the effects of rotor design parameters on stability.