Wind-Tunnel Investigation of Wind Deflectors for the MH-6M Mission Enhanced Little Bird Helicopter

The U.S. Army’s 160^th Special Operations Aviation Regiment (Airborne) employs the MH-6M Mission-Enhanced Little Bird helicopter with troops seated on external platforms on both sides of its fuselage. During cruise flight, these troops are subjected to such high wind speeds that the ability to perform their subsequent mission is degraded. The external personnel also add parasite drag to the helicopter, which decreases its performance, and increase the noise levels and turbulence in the cockpit, which interferes with its crew.

Prior research indicated that the wind could possibly be diverted away from the external personnel, to some degree, by attaching wind deflectors to the helicopter fuselage. This thesis explored that notion by investigating the effects of various wind deflector designs on a partial model of the MH-6M helicopter installed in a wind tunnel. The wind tunnel investigation included quantitative and qualitative flow visualization, parasite drag force measurements, and acoustical analysis of 15 wind deflector designs.

The investigation concluded that a simple curved plate wind deflector could effectively divert the airflow away from the external passengers, while simultaneously reducing their parasite drag, as well as the turbulence and associated noise. The degree of their effectiveness varied mainly with the wind deflector’s width, length, and angle. The effects of varying these parameters were analyzed to determine their optimum values for design and fabrication of a full-scale prototype wind deflector. The analyses suggested a prototype deflector width of approximately 18 inches, a deflection angle of 50 – 60 degrees, and a length that extends over the external personnel’s heads.

Additional files were included as Plate I CD ROM and Plate II DVD with physical copy.