ANTIRESONANT ROTOR ISOLATION FOR VIBRATION REDUCTION

This paper presents the follow-on development of an Improved Rotor Isolation System (IRIS) to minimize helicopter vibrations. Based on flight test experience gained with antiresonant rotor isolation systems designed for the BO-105 and the Company Owned Model 179 helicopter, a completely new and simplified reduced weight design was completed for the Boeing Vertol Model 237 entry in the U.S. Navy LAMPS competition. This design, which provided isolation throughout the maneuver range of −0.5g to +3.0g without bottoming, promised to be the lightest weight antiresonant isolation system yet proposed offering three isolation freedoms and only accounting for 1.3% of Design Gross Weight. The rationale and analysis leading to the design and the final arrangement are presented in detail together with flight test data acquired with the dynamically similar system installed on the Model 179.