The Aeroplane Speaks [40]
should be taken not to tighten the wire beyond barely taking up the slack.
Such a wire must be a little slack, or, as illustrated above, it will distort the framework. That, in the example given, will spoil the camber (curvature) of the surface, and result in changing both the lift and the drift at that part of the surface. Such a condition will cause the aeroplane to lose its directional stability and also to fly one wing down.
I cannot impress this matter of tension upon the reader too strongly. It is of the utmost importance. When this, and also accuracy in securing the various adjustments, has been learned, one is on the way to becoming a good rigger.
6. Wire Loops.--Wire is often bent over at its end in the form of a loop, in order to connect with a turnbuckle or fitting. These loops, even when made as perfectly as possible, have a tendency to elongate, thus spoiling the adjustment of the wires Great care should be taken to minimize this as far as possible. The rules to be observed are as follows:
(a) The size of the loop should be as small as possible within reason. By that I mean it should not be so small as to create the possibility of the wire breaking.
(b) The shape of the loop should be symmetrical.
(c) It should have well-defined shoulders in order to prevent the ferrule from slipping up. At the same time, a shoulder should not have an angular place.
(d) When the loop is finished it should be undamaged, and it should not be, as is often the case, badly scored.
7. Stranded Wire Cable.--No splice should be served with twine until it has been inspected by whoever is in charge of the workshop. The serving may cover bad work.
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. Don't 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.
Such a wire must be a little slack, or, as illustrated above, it will distort the framework. That, in the example given, will spoil the camber (curvature) of the surface, and result in changing both the lift and the drift at that part of the surface. Such a condition will cause the aeroplane to lose its directional stability and also to fly one wing down.
I cannot impress this matter of tension upon the reader too strongly. It is of the utmost importance. When this, and also accuracy in securing the various adjustments, has been learned, one is on the way to becoming a good rigger.
6. Wire Loops.--Wire is often bent over at its end in the form of a loop, in order to connect with a turnbuckle or fitting. These loops, even when made as perfectly as possible, have a tendency to elongate, thus spoiling the adjustment of the wires Great care should be taken to minimize this as far as possible. The rules to be observed are as follows:
(a) The size of the loop should be as small as possible within reason. By that I mean it should not be so small as to create the possibility of the wire breaking.
(b) The shape of the loop should be symmetrical.
(c) It should have well-defined shoulders in order to prevent the ferrule from slipping up. At the same time, a shoulder should not have an angular place.
(d) When the loop is finished it should be undamaged, and it should not be, as is often the case, badly scored.
7. Stranded Wire Cable.--No splice should be served with twine until it has been inspected by whoever is in charge of the workshop. The serving may cover bad work.
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. Don't 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.