Whirl testing has begun on the RAH-66 Comanche helicopter's bearingless main rotor (BMR) system at Sikorsky's 7,450kW (10,000hp) main-rotor whirl stand in Stratford, Connecticut. The tests will evaluate rotor performance, durability and aeromechanical stability, according to the Boeing Sikorsky Comanche Team. The BMR will also undergo a 100h endurance run before the first flight of the prototype in November. The Comanche's five-bladed BMR is designed to provide the RAH-66 with maximum manoeuvrability while minimising vibration and noise. A full-scale prototype of the Comanche BMR has already undergone 120h of testing in the NASA Ames wind tunnel.