APPLICATION OF A COMPREHENSIVE ANALYTICAL MODEL OF ROTORCRAFT AERODYNAMICS AND DYNAMICS (CAMRAD) TO THE MCDONNELL DOUGLAS AH-64A HELICOPTER

A model of the production McDonnell Douglas Helicopter Company/U.S. Army AH-64A helicopter was developed in a Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD) and applied for main rotor blade natural frequency and structural loads predictions. The CAMRAD results were compared to flight test data and the predictions of the McDonnell Douglas aeroelastic analysis programs Dynamic Analysis Research Tool (DART) and Rotor/Airframe Comprehensive Aeroelastic Program (RACAP). Studies were also made of the effects of various analytical options available in CAMRAD including dynamic stall, wake modeling and the number of bending and torsion degrees of freedom included in the structural analysis. The general conclusion drawn from these studies is that, while several modeling limitations were identified in the CAMRAD structural analyses, the structural loads predictions are as accurate as analysis codes which provide more representative models of the complex geometries and structures of the AH-64A rotor system. However, it is apparent that the CAMRAD analysis in its current form cannot be considered fully reliable for dynamics predictions for more advanced rotor systems such as the bearingless rotor designs being proposed for LHX and future AH-64 configurations.