Design and Optimization of a Wind Deflector for Round-Nose MD-500 Series Helicopters

This thesis examines the problem experienced by the numerous rotary wing operators whose operations require flight with personnel seated outside the fuselage or with doors off. This investigation is specific to the round nose configured MD-500 series aircraft due to test aircraft availability and the wide range of missions it conducts worldwide. During cruise flight, personnel exposed to the aircraft slipstream are subjected to high wind loads and extreme wind chill effects, compromising their ability to perform required tasks. External passengers also add to the overall helicopter parasite drag, decreasing its performance as well as interfering with the crew through increased noise, wind and turbulence in the cockpit. Prior research indicates that attachment of wind deflectors to the helicopter forward fuselage diverts the wind away from the fuselage, reducing overall parasite drag and slipstream effects on external passengers. The purpose of this investigation is threefold, identification of the structural requirements for airframe integration, design and fabrication of airworthy test deflectors, and evaluation of effects of the devices on external passengers, helicopter performance and pilot interface. Seven full-scale wind deflector configurations were flight tested at airspeeds of 0 to 80 knots. The deflector configured with a sweep angle of 50˚and width of 8 inches with Gurney flap provided for reductions of 52% in external passenger load, 2 psi main rotor torque in 80 knot cruise and significantly less wind, noise and turbulence in the cockpit.