Experimental Evaluation of Analytically Shaped Helicopter Rotor Hub-Pylon Configurations Using the Hub Pylon Evaluation Rig,

The hub-pylon evaluation rig, a new facility for wind tunnel experiments on large scale helicopter rotor hub-pylon configurations, was used to determine the variation of hub-pylon drag with shaft angle and height, and pylon angle parameters. In addition, a series of low drag area rule fairings and shaft fairings were evaluated. The results indicate that the proper selection of shaft angle with respect to the pylon and pylon angle of attack can yield a twenty percent reduction in drag for a given shaft angle of attack. An additional reduction in drag of at least twenty percent is achievable with a properly designed area rule fairing. (Author)