03.22.08
Should a strand become broken
Should a strand become broken, then the cable should be
replaced at once by another one.
Control cables have a way of wearing out and fraying
wherever they pass round pulleys. Every time an aeroplane
comes down from flight the rigger should carefully examine
the cables, especially where they pass round pulleys. If
he finds a strand broken, he should replace the cable.
The ailerons balance cable on the top of the top plane
is often forgotten, since it is necessary to fetch a high pair
of steps in order to examine it. Dont slack this, or some
gusty day the pilot may unexpectedly find himself minus the
aileron control.
CONTROLLING SURFACES.–The greatest care should be
exercised in rigging the aileron, rudder, and elevator properly,
for the pilot entirely depends upon them in managing the
aeroplane.
The ailerons and elevator should be rigged so that, when
the aeroplane is in flight, they are in a fair true line with the
surface in front and to which they are hinged.
If the surface to which they are hinged is not a lifting
surface, then they should be rigged to be in a fair true line
with it as illustrated above.
If the controlling surface is, as illustrated, hinged to the
back of a lifting surface, then it should be rigged a little below
the position it would occupy if in a fair true line with the
surface in front. This is because, in such a case, it is set
at an angle of incidence. This angle will, during flight,
cause it to lift a little above the position in which it has been
rigged. It is able to lift owing to a certain amount of slack
in the control wire holding it–and one cannot adjust the
control wire to have no slack, because that would cause it
to bind against the pulleys and make the operation of it too
hard for the pilot. It is therefore necessary to rig it a little
below the position it would occupy if it was rigged in a fair
true line with the surface in front. Remember that this
only applies when it is hinged to a lifting surface. The
greater the angle of incidence (and therefore the lift) of the
surface in front, then the more the controlling surface will
have to be rigged down.
As a general rule it is safe to rig it down so that its trailing
edge is 1/2 to 3/4 inch below the position it would occupy if in
a fair line with the surface in front; or about 1/2 inch down for
every 18 inches of chord of the controlling surface.
When making these adjustments the pilots control levers
should be in their neutral positions. It is not sufficient
to lash them. They should be rigidly blocked into position
with wood packing.
The surfaces must not be distorted in any way. If
they are held true by bracing wires, then such wires must be
carefully adjusted. If they are distorted and there are no
bracing wires with which to true them, then some of the
internal framework will probably have to be replaced.
The controlling surfaces should never be adjusted with
a view to altering the stability of the aeroplane. Nothing
can be accomplished in that way. The only result will be
to spoil the control of the aeroplane.
FABRIC-COVERED SURFACES.–First of all make sure
that there is no distortion of spars or ribs, and that they are
perfectly sound. Then adjust the internal bracing wires
so that the ribs are parallel to the direction of flight. The
ribs usually cause the fabric to make a ridge where they occur,
and, if such ridge is not parallel to the direction of flight,
it will produce excessive drift. As a rule the ribs are at
right angles to both main and rear spars.
The tension of the internal bracing wires should be just
sufficient to give rigidity to the framework. They should
not be tensioned above that unless the wires are, at their
ends, bent to form loops. In that case a little extra tension
may be given to offset the probable elongation of the
loops.