The Aeroplane Speaks. Fifth Edition

Now, after having tensioned the cables sufficiently to take out the snatch, place the levers in their neutral positions, and move them to and fro about 1/8 inch either side of such positions. If the adjustment is correct, it should be possible to see the controlling surfaces move. If they do not move, then the control cables are too slack. FLYING POSITION.--Before rigging an aeroplane or making any adjustments it is necessary to place it in what is known as its "flying position." I may add that it would be better termed its "rigging position." In the case of an aeroplane fitted with a stationary engine this is secured by packing up the machine so that the engine foundations are perfectly horizontal both longitudinally and laterally. This position is found by placing a straight-edge and a spirit-level across the engine foundations (both longitudinally and laterally), and great care should be taken to see that the bubble is exactly in the centre of the level. The slightest error will assume magnitude towards the extremities of the aeroplane. Great care should be taken to block up the aeroplane rigidly. In case it gets accidentally disturbed while the work is going on, it is well to constantly verify the flying position by running the straight-edge and spirit-level over the engine foundations. The straight-edge should be carefully tested before being used, as, being generally made of wood, it will not remain true long. Place it lightly in a vice, and in such a position that a spirit-level on top shows the bubble exactly in the centre. Now slowly move the level along the straight-edge, and the bubble should remain exactly in the centre. If it does not do so, then the straight-edge is not true and must be corrected. This should never be omitted.