GB621212A - Improvements relating to control systems for controlled aerofoils of aircraft - Google Patents

Abstract

621,212. Aircraft control systems. PRICE, H. L., and SPERRY GYROSCOPE CO., Ltd. May 6, 1946, Nos. 13705 and 20639. [Class 4] [Also in Group XXXVIII] A strain gauge 58 is employed to measure the strain in the torsion bar spring 22 of an aircraft control system comprising a spring tab 36 and a main control surface 34, and the output from the strain gauge 58 controls a motor 26 to apply a force to the main control surface which is proportional to the strain in the torsion bar 22 and thus to reduce the effort required on the control stick 20. As shown, the motor 26 is also controlled by the output from a strain gauge 66 in the connection to the spring tab 36, and develops an output p 2 X+q 2 Y, where p 2 and q 2 are constants and X and Y are the forces exerted on the main part 34 of the control surface 8 on the spring tab 36 respectively. A further motor 54 operates on a screw connection in the rigid connection to the spring tab and is controlled by the strain gauges 58, 66 to give an output p 1 X+q 1 Y, where p 1 and q 1 are also constant. Preferably, p 1 q 2 =(1-p 2 )(1-q 1 ). A clutch 12 is automatically released to enable manual control if the power supply to the motors 26, 54 fail, and an irreversible connection 38 such as that described in Specification 565,920 may be included in the connection to the spring tab 36. In one form, corresponding to q 1 =1, the motor 54 is of the hydraulic positional follow-up type, and the motor 26 is of the type described in Specification 545,296. Provision is made so that the input to the motors may be provided by an automatic pilot. The motor 54 may have a long-time constant so that it operates mainly to trim the spring tab, and a manual trimming control may be connected to the motor 54 by a flexible shaft 56.