Aeromechanics for a High Advance Ratio Coaxial Helicopter

A comprehensive analysis for evaluating performance and vibratory loads of a coaxial helicopter is developed, and some validations are carried out against existing experimental data. The methodology is extended from baseline UMARC to include interactional rotor wake between the coaxial rotors, modeling of relative phase between rotors and trim strategies for a coaxial helicopter. The simulation is used to define a flight envelope for an experimental rotor being developed by the University of Texas at Austin for testing in the Glenn L. Martin Wind Tunnel. Vertical hub loads and total rotor power are observed to decrease with increasing lift offset while blade root bending moments tend to decrease.