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Vertical‐Plane Pendulum Absorbers for Minimizing Helicopter Vibratory Loads

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This paper discusses the use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads. The paper describes qualitatively the concept of the dynamic absorbers and presents results of analytical studies and flight tests showing the degree of reduction in vibratory loads attainable. Operational experience of vertical plane dynamic absorbers on the OH‐6A helicopter is also discussed. Other approaches evaluated included providing control of blade first and second mode natural frequencies by means of anti‐node weights and by use of preloaded internal cables. Flight tests did not show these methods to be sufficiently effective. Hub‐mounted vertical plane pendulums were flown and proved to be effective, but considerations of drag and weight were unfavorable for this configuration. Fuselage‐mounted non‐rotating dampers were eliminated because of the difficulty of tuning to a sufficiently wide range of frequency. Fuselage‐mounted centrifugal pendulum dampers were considered impractical from the standpoint of space requirements and mechanical complexity.

Document Type: Research Article


Affiliations: Hughes Helicopters, Culver City, California

Publication date: 1974-10-01

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  • The Journal of the American Helicopter Society is the world's only scientific journal dedicated to vertical flight technology. It is a peer-reviewed technical journal published quarterly by AHS International and presents innovative papers covering the state-of-the-art in all disciplines of rotorcraft design, research and development. (Please note that AHS members receive significant discounts on articles and subscriptions.)

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