HELICOPTER OBSTACLE STRIKE TOLERANCE

Design concepts for improving the tolerance of helicopters to in-flight obstacle strikes are derived for the main rotor, tail rotor, fuselage and landing gear (fixed system), and main rotor hub and controls. Selected concepts are comparatively analyzed based on their functional, operational, and aircraft integration characteristics, and on their strike damage cost-reduction potential. Detailed definition of the in-flight obstacle strike problem provided a sound basis for the derivation and selection of the design concepts having the greatest potential for improving helicopter strike tolerance. Problem definition included determination of the types of obstacles struck and frequency; areas of helicopter struck and frequency; cost of strikes; and diameter and type of trees and wires for which current systems have reasonable strike tolerance. Obstacle strike tolerance design criteria for future systems are proposed, as are suggestions for improving the obstacle strike protection of current systems through retrofit.