A.L.1 PART 1 - DESCRIPTIVE
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22A. Electric follow-up tail
(a) General
An electrical interconnection enables the variable-incidence
tailplane to follow-up elevator movement. A more power-
ful elevator booster and a faster rate tailplane actuator are
fitted. Used together they give greater manoeuvrability at
high mach numbers and the booster increases available
elevator angle (and hence tailplane angle before jack
stalling occurs.
(b) Selectors and indicators
(i) A TAILPLANE ON/OFF switch, by means of which
the interconnection may be selected, is fitted on the
port shelf. The tailplane indicator is so arranged to
indicate when the tailplane is functioning as a flying
control, i.e. the indicator moves when the control
column is deflected as well as when the trim switch
is actuated.
(ii) The circuit is so arranged that when the cover of the
standby trim switch is raised, both the main actuators
and the interconnection are isolated.
(c) Function
(i) Whenever the interconnection is switched ON, and
electric power is available, it functions irrespective of
whether the elevator is in Power or in Manual. It is
arranged in the form of a follow-up linkage, so that
for a given stick deflection and tailplane trim position
a predetermined relationship exists between tailplane
and elevator angles. A linkage attached to the ele-
vator carries a switch arm, one end of which moves
between two micro-switches. Movement of the ele-
vator relative to the tailplane energises one of these
switches which operates the tailplane actuator to
move the tailplane. When the tailplane reaches the
required position the micro-switch is de-energised and
tailplane movement stops, leaving the elevator de-
flected relative to the new position of the tailplane.
(ii) To prevent continual hunting of the tailplane actuator,
the elevator has a small range of movement over
which the micro-switches are not selected.
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