Aeromechanics investigation of tiltrotor transition maneuver

Abstract

Aeromechanics analysis is performed using the comprehensive analysis code RCAS (Rotorcraft Comprehensive Analysis System) to study the transient conversion maneuver of a tiltrotor. The analytical model is based on the XV-15 research tiltrotor aircraft in size and dynamic characteristics. A generic (not representative of XV-15) tiltrotor control system is developed to simulate conversion maneuver. The calculation begins with a trim analysis at hover, which is followed by the conversion maneuver. During the maneuver analysis, the pilot control model is activated to fly the aircraft following a desired airspeed profile and zero altitude change. Time histories of vehicle dynamics, rotor controls, rotor flapping, rotor performance and blade structural loads are investigated for various transient conversion maneuver flight conditions. The aircraft longitudinal acceleration is larger for the faster conversion (shorter conversion time) and for the higher cruise speed (conversion end speed). The aircraft acceleration during the transient maneuver has a significant influence on the rotor performance and loads.