AN INTEGRATED ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF HELICOPTER HUB DRAG

This paper describes an integrated program which uses a viscous wing/body computer code to analyze low drag concepts of a current helicopter. Based on this analysis, full-scale wind tunnel models are fabricated and tested. The resulting experimental data are then compared to predictions and areas of agreement are defined. The viscous wing/body computer code is Program DRAG which includes engine inflow/exhaust modeling and main rotor hub representation. The full-scale experimental model represents the YAH-64 and the testing was conducted in the NASA/Langley V/STOL tunnel. The data presented and discussed indicate that Program DRAG is acceptable for designing hub/pylon modifications. In addition, it is shown that engine air flow has a significant effect on model pylon drag. The development of typical hub/pylon fairings and the importance of sealing are discussed.