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Prediction of the dynamic characteristics of helicopters in constrained flight

Part of: 75 year anniversary of Aeronautical Engineering at Glasgow University

Published online by Cambridge University Press:  04 July 2016

D. G. Thomson  and
R. Bradleyt
D. G. Thomson
Affiliation:
Department of Aerospace Engineering, University of Glasgow
R. Bradleyt
Affiliation:
Department of Aerospace Engineering, University of Glasgow
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Abstract

In circumstances where a pilot is forced to follow a specified flight path, such as during a landing approach or in nap-of-the-earth conditions, it will be shown that there is an apparent modification of the helicopter's stability characteristics. This effect is identified in helicopter flight data from nap-of-the-earth agility trials where oscillations are observed in the time histories of the pilot's control inputs and the vehicle's response. A technique of predicting the nature of these oscillations using a linearised helicopter mathematical model is developed. The model is inverted to give the response of the unconstrained states in terms of those strongly controlled by the need to remain on a specific flight path. Results are compared with data from flight trials and it is shown that good correlation between the period of the oscillations in the flight data and the predicted values can be obtained.

Type
Research Article
Information
The Aeronautical Journal , Volume 94 , Issue 940 , December 1990 , pp. 344 - 354
Copyright
Copyright © Royal Aeronautical Society 1990 

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Footnotes

*

Royal Society University Research Fellow

†

Lecturer

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