AN INVESTIGATION OF THE FLOW FIELD AND DRAG OF HELICOPTER FUSELAGE CONFIGURATIONS

An investigation has been made to analytically determine the flow field about a helicopter fuselage and to apply the results to the prediction of parasite drag. The analytical methods are currently restricted to nonlifting bodies in nonyawed flow. The flow field is determined by using the Douglas-Neumann computer program for the potential field and a boundary layer analysis based upon the small cross-flow assumption. Pressure distributions from test data and the Douglas-Neumann program correlate very well except for areas of separated flow. Also, boundary layer velocity profiles obtained from test data and the boundary layer analysis agree very well. An empirical approach based on test data is used to approximate the pressure in the separated region. Drag is obtained by numerical Integration of the pressure and skin friction distribution. Agreement is reasonable between test data and the drag obtained by the summation process. The analytical methods have potential application in the design of helicopter fuselages of minimum parasite drag.