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Some Notes on Helicopter Stability Under Constraint

Published online by Cambridge University Press:  04 July 2016

P. E. Kumar*
Affiliation:
Formerly Servotec Ltd, now with HSA (Hatfield and Toulouse)

Extract

The concept of stability under constraint had been developed by Neumark and applied with considerable success to predict the speed instabilities in the flight of aircraft below minimum drag speed. This concept involves the removal (or partial removal) of one or more degrees of freedom of an aircraft by the deliberate application of some control to keep a chosen element of disturbance at a constant value. A partial constraint could thus be introduced in practice by a pilot trying to keep the wings level with the horizon by the use of aileron control, or keeping attitude constant with the use of elevator. Pinsker has recently used bank angle constraint stability of an aircraft as a means of defining a minimum acceptable value of nv.

This present note considers some aspects of longitudinal stability under constraint as applicable to the flight of a helicopter in the forward and the hover modes.

Type
Technical Notes
Copyright
Copyright © Royal Aeronautical Society 1971 

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References

1. Neumark, S. Problems of longitudinal stability below minimum drag speed, and theory of stability under constraint. R & M 2983, 1953.Google Scholar
2. Pinsker, W. Directional Stability in flight with bank angle constraint as a condition for defining a minimum acceptable value of nv. R & M 3556, 1968.Google Scholar
3. Bramwell, A. R. S. Longitudinal stability and control of a single rotor helicopter. R & M 3104, 1959.Google Scholar
4. Seckel, E. Stability and Control of Airplanes and Helicopters. 1964.Google Scholar
5. Hess, and Smith, . Calculation of Potential Flows about arbitrary bodies. Prog in Aero Sci, Vol 8 1967.Google Scholar