GB356418A - Improvements in and relating to steering aileron or elevator mechanism for aircraft or other craft - Google Patents

Abstract

356,418. Arrangement of springs. BRUCE, R. A. HILL, G. T. R., RATCLIFFE, J. W. and PETTERS, Ltd., Westland Works, Yeovil, Somerset. Aug. 5, 1930, No. 23478. [Class 108 (iii).] Spring mechanism employed for the relieving the pilot of air- or water-craft from loads occasioned in operating control surfaces such as occur when one engine of a two-engine machine stops, is provided with means for obtaining any desired degree of biasing force throughout the whole range of movement. The device is shown diagrammatically in Fig. 4, in which b is a rudder bar, a a main helical spring operating either in tension or compression, and m is a balancing spring operating in compression. The strength of springs a, m is so adjusted that the tension on a when moved as shown is balanced by the pressure of spring m on a bell-crank lever h linked by a rod to the end of the main spring ; similarly in the reverse position substantially no load is placed on the rudder bar by the springs. By increasing the compression of the balancing springs m, a destabilizing force is introduced on displacement of the control surface assisting the pilot to overcome the aerodynamic loads. By shortening or extending the spring a, the balance of the arrangement is upset and a biasing force introduced causing the control surface to be maintained over to one side or other of its neutral position. In an application to an aircraft rudder control, Fig. 2, the spring a is fixed to one end d of a tube c connected by levers and a link to the rudder bar ; the other end of spring a is fixed to a nut e screwed on a threaded tube f extending within tube c and mounted in a trunnion bearing upon a fixed part of the machine structure. The bell crank h is also mounted on this bearing and is connected at one arm to the end d of tube c and at the other arm to compression springs m which in the neutral position are in line with this arm. A handle g rotates the tube j to cause extension or compression of spring a by moving nut e axially, and a nut n enables the position of the abutment of springs m to be set. Specification 190,560, [Class 108 (iii), Springs &c.], is referred to.