Design of a Cruise-Efficient Compound Helicopter

A slowed-rotor compound helicopter is conceptually designed using a multifidelity approach, showing the potential for significant efficiency improvements above conventional helicopters. The cruise tip speed and bilinear twist distribution are optimized using the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD II). System-level metrics are computed using the NASA Design and Analysis of RotorCraft (NDARC) program to show top-level payoffs. An aeroperformance map is generated using comprehensive analysis for the optimum twist distribution, providing calibration data for the main rotor model within NDARC. Effects of disk loading and wing loading on the size of the slowed-rotor compound helicopter are analyzed, and off-design performance is computed. Rotor-wing interference effects are analyzed using CAMRAD II for several wing vertical locations.