DESIGN OPTIMIZATION OF ROTOR BLADES FOR IMPROVED PERFORMANCE AND VIBRATION

A multidisciplinary optimization tool for helicopter rotor blade design has been developed which efficiently and effectively determines blade aerodynamic and structural designs for improved performance and reduced fuselage vibrations. The comprehensive analysis code, CAMRAD/JA, forms the analysis core of the program while CONMIN's method of feasible directions provides the optimization algorithm. Blade aerodynamic and structural properties are used as design variables while rotor power required, dynamic hub loads and/or fuselage vibrations may be minimized as the objective function. The present paper describes a comprehensive application of the optimization tool to the McDonnell Douglas Helicopter Company AH-64A helicopter, including the introduction of additional design variables and objective function options. Results are presented for forward flight performance improvement, fuselage vibration reduction, and combined performance/vibration optimization. The optimized designs are shown to provide significant improvements in the design objectives. The mechanisms for the improvements and the practical suitability of the designs are evaluated.