Performance Optimization of the NASA Large Civil Tiltrotor

Abstract

Abstract : Performance optimization and analysis is presented for a Large Civil Tiltrotor (LCTR2). Intended to replace regional airliners over medium ranges, LCTR2 is designed to carry 90 passengers for 1000 nm or greater, with performance of 300 knots at 28,000-ft altitude. Design features include low hover and cruise tip speeds of 650 and 350 ft/sec, respectively. The paper is primarily concerned with rotor aerodynamic optimization for performance, including rotor/wing interference calculations. Twist, taper, and solidity optimizations are presented, along with an analysis of flight performance in turns. Hover/cruise performance tradeoffs for different cruise tip speeds are also presented. A free-wake model was used for all rotor analyses, computed by the CAMRAD II comprehensive analysis code. Aircraft design was done with the RC sizing code, developed by the U. S. Army Aeroflightdynamics Directorate.