Aerodynamic Effect of Strakes on Two-Dimensional Tail Boom Models of OH- 58A and OH-58D Helicopters
NATIONAL AERONAUTICS AND SPACE ADMIN LANGLEY RESEARCH CENTER HAMPTON VA
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During hover, helicopters experience significant aerodynamic forces on the tail boom caused by the wakes of the main and tail rotors and by crosswinds. These effects were investigated in the Langley 14- by 22-Foot Subsonic Tunnel on large-scale two-dimensional tail boom models with cross sections representative of the U.S. Army OH-58A and OH-58D helicopters. The effects of longitudinal strakes attached to the models were also investigated. The results with the strakes installed showed a significant improvement at conditions representative of right sideward flight by reducing the side force on the booms. Calculations indicated a 5- to 6-percent savings in tail rotor power. An increased download on the booms was noted because of the strakes.