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Technical Notes: A Simple Autorotative Flare Index

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An index which corresponds to the relative ease with which a helicopter can made an autorotative flare to a landing is derived from simple momentum relations. The index is proportional to rotor kinetic energy and inversely proportional to the product of gross weight and disk loading. As gross weight of a given helicopter is increased, the value of the index decreases rapidly. Operation at altitude decreases the index for any given weight. Although it does not acccount for some factors which influence the capability for a safe power‐off landing, such as landing gear design and pilot visibility, the index is a useful guide whenever other elements are approximately equal.

Document Type: Research Article


Affiliations: Sikorsky Aircraft, Stratford, Connecticut

Publication date: 1984-07-01

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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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