# Evaluation of helicopter agility through inverse solution of the equations of motion

Thomson, Douglas G. (1987) Evaluation of helicopter agility through inverse solution of the equations of motion. PhD thesis, University of Glasgow.

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Printed Thesis Information: https://eleanor.lib.gla.ac.uk/record=b1287067

## Abstract

Helicopter agility in nap-of-the-earth flight is widely recognised
to be of great importance. Despite this. a general method of quantifying
agility does not exist. All previous attempts to quantify agility have
been restricted either to flight tests or to simple kinematic modelling -
both with obvious disadvantages. A method of quantifying helicopter
inherent agility. the agility of the configuration independent of the
pilot. utilising inverse solutions of the equations of motion has been
developed.
A value for the inherent agility of a helicopter is given by
studying its performance over a series of standard manoeuvres. The
manoeuvres used represent typical tasks undertaken by the configuration
under study. The combination of these tasks represent the helicopter's
operational role. The helicopter's performance over these standard
manoeuvres is found by using an inverse solution of the equations of
motion - calculation of the control. and resulting state. time histories
needed to fly a given flight path. A six degrees of freedom non-linear
mathematical model is used to simulate single main and tail rotor
helicopter flight dynamics. The helicopter's performance over each
manoeuvre is rated by a quadratic performance function of the state and
control variables. The performance function is weighted in such a manner
as to penalise undesirably large displacements in the state and control
variables of particular importance to that manoeuvre (e.g. large nose down
attitude changes in accelerated flight are heavily penalised). An Agility
Rating is awarded to a helicopter on the basis of its performance over a
wide range of similar manoeuvres. a measure of total inherent agility
being a function of the agility ratings for all the manoeuvres relevant to
the helicopter's role.
The method is illustrated by applying it to two agility studies.
Firstly. it is used to show how an optimum tailplane area can be
calculated for manoeuvres in the longitudinal plane. Then an "Advanced
Rotor Helicopter" is compared with a contemporary battlefield helicopter.

Item Type: Thesis (PhD) Doctoral T Technology > TL Motor vehicles. Aeronautics. Astronautics College of Science and Engineering Bradley, Mr. Roy and Caldwell, Dr. Alistair 1987 Ms Mary Anne Meyering glathesis:1987-4927 Copyright of this thesis is held by the author. 06 Feb 2014 13:24 06 Feb 2014 13:26 http://theses.gla.ac.uk/id/eprint/4927

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