Evaluation of an Energy Distribution System for Helicopter Landing Gears During Hard Landing
Final rept. 1 Mar 1977-Sep 1978
HUGHES HELICOPTERS INC CULVER CITY CA
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An experimental program was conducted to evaluate a landing gear concept that redistributes the impact energy of an autorotational landing. This landing gear concept redistributes the impact energy by providing an interconnection between the front and rear landing gears. Through the interconnection, as the rear landing gear moves from the flight position toward the full compressed position under landing impact, the front gear is impelled to move from the flight position toward the fully extended position. When these motions have been accomplished, the skids remain on the ground surface throughout the landing, greatly reducing the pitching moments. The landing gear was drop tested to demonstrate the effects of sink rate, gross weight, center- of-gravity CG location, touchdown attitude both pitch and yaw, ground resonance, system damping, and spring rate. The testing included drop velocities up to 19.5 feet per second and simulated forward and lateral speed landings. For purpose of design and development, the OH-6A helicopter was used as the baseline aircraft, and the landing gear was designed to require minimum modification to the OH-6A. The results of the testing showed that the interconnected landing gear reduces the nosedown pitching velocities and angles during autororation landings. A cost analysis indicated that incorporation of the interconnected landing gear in new production aircraft would result in a return on investment greater than 21.