A Full-scale Experimental Feasibility Study of Helicoptek Rotor Isolation Using the Dynamic Antiresonant Vibration Isolator

This report contains the results of a full-scale experimental feasibility study of rotor isolation employing the Dynamic Antiresonant Vibration Isolator (DAVI) . The full-scale experiments were performed on a UH-2 helicopter fuselage isolated from a simulated rotor and transmission. Tests were conducted for three directions of vibratory input at the hub on the nonisolated vehicle and then compared to results obtained for the isolated vehicle. Tests on the isolated helicopter were conducted for two-bladed, threebladed, and four-bladed rotor configurations. These rotor configurations were simulated by proper tuning of the DAVI isolation system to the predominant excitation frequency of the rotor systems. Results of this experimental study on a 6500-pound helicopter show that rotor isolation is feasible. Excellent reduction of vibration throughout the fuselage was obtained at the predominant excitation frequency (n-per-rev) . This was accomplished with low static deflection, minimum weight penalty, and small relative vibratory deflections between the rotor and fuselage.