Aeromechanics Analysis of a Heavy Lift Slowed-Rotor Compound Helicopter

A heavy lift slowed-rotor tandem compound helicopter was designed as a part of the NASA heavy lift rotorcraft systems investigation.The vehicle is required to carry 120passengers over a range of 1200nauticalmiles and cruise at 350 knots at an altitude of 30,000 feet. The basic size of the helicopter was determined by the United States Army Aeroflightdynamics Directorate’s design code RotorCraft. Then performance, loads, and stability analyses were conducted with the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Design II. Blade structural design (blade inertial and structural properties) was carried out using the loading condition from theComprehensive AnalyticalModel of Rotorcraft Aerodynamics andDesign II. A rotor parametric study was conducted to investigate the effects of the twist, collective, tip speed, and taper on aircraft performance. Designs were also developed for alternate missions to explore the influence of the design condition on performance. Nomenclature A = rotor disk area CD = drag coefficient Cf = skin friction coefficient CT = rotor thrust coefficient CW = rotor weight coefficient D=q = airframe drag divided by dynamic pressure L=D = aircraft effective lift-to-drag ratio M = Mach number Mat = advancing tip Mach number P = aircraft power Preq = required power R = rotor radius Swet = wetted area V = flight speed Vbr = best range flight speed W = gross weight W=A = disk loading = advance ratio = air density = solidity