Wind Tunnel Tests of Large- and Small-Scale Rotor Hubs and Pylons

Abstract : The Army YAH-64 and UH-60A helicopters were studied to determine optimum wind tunnel test procedures and to expand the experimental data base on drag reduction for rotor hubs and pylons. Full- and reduced-scale models of these helicopters were fabricated. The Hub Pylon Evaluation Rig (HPER) and the Generalized Rotor Modeling System (GRMS) were used for the experimental testing, conducted in the NASA/Langley V/STOL wind tunnel. Only the YAH-64 models underwent wind tunnel testing during this contracted effort. Plans are under way for testing of the UH-60A models. All configurations were subjected to viscous analysis using Program DRAG, a configuration modeling program. This effort included evaluation of hub fairings, pylon fences, rotor wake flow, hub rotation, engine air flow, fuselage parasite drag, empennage flow, and stabilators. The DRAG program was validated by correlation of predicted and experimentally obtained surface pressures.