Investigation of BERP-Shape Tip Design on an Apache Rotor Blade

The British Experimental Rotor Programme (BERP) tip design is well known for its superior performance for high speed flight. This paper revisits the BERP design by presenting a parameterized model of the planform design based on published data and investigating its performance on the Apache rotor blade. The underlying airfoil sections, HH02 and NACA64A006, are retained in a new Apache BERP-shape rotor blade. The performance of the Apache BERP-shape rotor blade is evaluated for hover and forward flight by using US Army CREATE™-AV Helios software and compared with the Apache baseline rotor blade. The results are presented in the form of rotor thrust, rotor torque, figure of merit, trim condition, sectional blade loading and pressure distribution. A visualization of complex vortex structures is provided to offer insight into the airflow characteristics at different flight conditions.