An Experimental and Analytical Investigation of the Potential Flow Field, Boundary Layer, and Drag of Various Helicopter Fuselage Configurations
ARMY AIR MOBILITY RESEARCH AND DEVELOPMENT LAB FORT EUSTIS VA EUSTIS DIRECTORATE
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An investigation has been performed to analytically determine the flow field about a helicopter fuselage and to apply the results to the prediction of parasite drag. The analytical method is 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 distribution correlation between test data and the Douglas-Neumann program is very good except for areas of separated flow. Agreement is also good between boundary layer velocity profiles obtained from test data and from the boundary layer analysis. 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 method has potential application in the design of helicopter fuselages of minimum parasite drag.