An Assessment of RCAS Performance Prediction for Conventional and Advanced Rotor Configurations

The US Army's Rotorcraft Comprehensive Analysis System (RCAS), was validated for aerodynamic performance for a variety of isolated rotor configurations in hover and forward flight. Validation cases included a wide variety of key rotor configurations, covering various scales (small-scale to full-scale), twist distributions (zero twist, moderate linear twist, non-linear twist, and high non-linear twist), tip shapes (rectangular, swept, swept-tapered, tapered, and anhedral), and flight conditions (hover to high-speed forward flight). A free-vortex wake model was used for hover performance, while a prescribed vortex wake model was sufficient for forward flight performance. The validation study showed good correlation with test data using the best practices for the vortex wake modeling parameters.