GB625636A - Improvements relating to the control of aircraft - Google Patents

Abstract

625,636. Controlling aircraft. WILLIAMS, D. Aug. 13, 1947, No. 22511. [Class 4] An aircraft is provided with means for detecting relative twisting of parts of an aerofoil and for initiating in accordance with such twisting an operation for varying the lift or lift moment on the aerofoil to reduce the resultant air-loads thereon. In the arrangement shown, an open-sided torsion cell is provided near a wing tip, the relative movement of the opposite sides, due to twisting of the cell as the result of gusts, being utilized to move a load-relieving flap 8.- The cell is formed between spanwise and chordwise extending spars 2 and 5, 6 respectively by slitting the aerofoil skin at 3, 4 in a chordwise direction between the spar 2 and the trailing edge, and by slitting the latter between the slits 3, 4. A pseudo web 7, also slit in the spanwise direction, is provided near the trailing edge of the torsion cell, the relative movement of the two portions of the web being utilized to operate the flap 8, either directly or through a servomotor 9. A unit 10 is provided between the web 7 and servomotor 9 for differentiating between gradual changes of air load due to normal movements of the pilot's controls and sudden changes due to gusts, the latter only causing operation of the servomotor. As shown in Fig. 3, the unit 10 comprises a movable self-centring cylinder 11 containing a dashpot piston 12 and piston-rod 13. The latter is connected to the air load or gust responsive device and the cylinder is connected to the servo unit by a rod 14. The piston 12 moves freely in the cylinder 11 with slow changes of air load, but a sudden change results in movement of both the piston and cylinder to cause operation of the servomotor.