A Full-Scale Test of the McDonnell Douglas Advanced Bearingless Rotor In the NASA Ames 40- by 80-Ft Wind Tunnel

The McDonnell Douglas Helicopter Company and NASA have tested a full-scale, advanced bearingless rotor in the 40- by 80- foot wind tunnel at Ames Research Center. The project goals were to obtain performance, loads, stability, and acoustics data for a state-of-the-art rotor system over a wide range of operating conditions, and also to measure the effects of open-loop Higher Harmonic Control (HHC) inputs on these attributes. The five-bladed, bearingless rotor was a pre-production version of the MD Explorer rotor system. The nominal "1g" thrust of the rotor was taken to be 5800 lbs for this test. The rotor was successfully tested over a wide range of operating conditions including speeds of over 200 knots, an advance ratio of 0.49, and thrusts of over 10,000 lbs, a Ct/σ of 0.13. The HHC test conditions included a transition flight case, a blade-vortex-interaction case, and a typical cruise flight case. The data are now part of the Rotor Data Reduction System (RDRS) database at Ames and the ASAP database at McDonnell Douglas.