On the benefit of an active horizontal tailplane to the control of the single main and tailrotor helicopter

Houston, Stewart S. (1984) On the benefit of an active horizontal tailplane to the control of the single main and tailrotor helicopter. PhD thesis, University of Glasgow.

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Abstract

Possible helicopter flight mechanics benefits associated with the
use of an actively controlled horizontal tailplane are identified,
influencing the areas of agility and manoeuvrability. In both cases,
control strategies are postulated and implemented by means of control
laws. They are then used with mathematical descriptions of the helicopter
in digital computer simulations of manoeuvres to quantitfy the benefits.
In the field of helicopter agility, use of a relatively small
horizontal tailplane is shown to enhance agility, relative to the
helicopter with a fixed tailplane. Popup maneouvres to SOm can be flown up
to 7% faster with the active tailplane; alternatively, geometrically
tighter manoeuvres can be flown to the extent of reducing manoeuvre
distance by up to 10%. The control law moves the tailplane proportionally
with the contributions of the three rotor controls and helicopter pitch
rate to the longtitudinal component of hub moment. It is however suggested
that a tailplane control law based on functions of pitch attitude would be
applicable to a wider range of manoeuvres than the popups simulated.
Helicopter manoeuvrability is enhanced by using the tailplane to
decouple the pitch attitude from the flight path. The benefits are
demonstrated by simulation of the acquisition and tracking of an airborne
target. For a helicopter with the conventional pattern of control,
significant changes in flight path result when the target is tracked with
fuselage pointing; by comparison, the helicopter with a decoupled flight
path and attitude controller changes flight path and speed by a negligible
amount. It is suggested that this mode of control may be more generally
applicable to control of the helicopter in that it mitigates the
speed/flight path/attitude compromise the pilot faces in flying his
aircraft, or the possibly large hub moments when accelerating or
decellerating.
The philosophy behind the use of the active tailplane differs from
that of contemporary applications of moveable tailplanes in that it is an
integrated element of the flight control system endowing (in its own
right) control capabilities on the helicopter that are otherwise precluded
by configuration. The addition of this extra control demands active
control technology for several reasons: the applications require full
control authority; the control laws are multivariable and change with
speed; and the cockpit control setup would have to be simplified to the
extent of the radical changes facilitated by active control technology.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: T Technology > TL Motor vehicles. Aeronautics. Astronautics
Colleges/Schools: College of Science and Engineering > School of Engineering
Supervisor's Name: Supervisor, not known
Date of Award: 1984
Depositing User: Mrs Marie Cairney
Unique ID: glathesis:1984-4919
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Feb 2014 10:13
Last Modified: 05 Feb 2014 10:32
URI: http://theses.gla.ac.uk/id/eprint/4919

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