Numerical analyses of different state of flight of new concept coaxial rotor dedicated to unmanned helicopters

Abstract

Paper presents a concept analysis of a resilient coaxial main rotor designed in the Warsaw Institute of Aviation which incorporates features of a standard joint rotor with a rigid Active Blade Concept (ABC) rotor. The combination of two extreme cases aims to increase the cruising speed compared to classical joint rotors and cost reduction compared to technologically advanced ABC rotor. In the paper detailed numerical analysis of the rotor has been carried out based on the data obtained during bench and field tests carried out on the rotor blades and the rotor assembly. The calculations were conducted for envelope of deferent flight state: hover, horizontal flight level with different speeds, pull-up maneuver and analysis of high-speed flight (over 300 km/h). Results of calculations among others prove that a properly selected stiffness of the rotor blade attached to a rigid rotor hub allows for reduction of the separation distance between rotors compared to coaxial rotors with articulated blades.