Patent GB-527549-A (GB)
Title: Improvements in or relating to actuating and controlling movable parts of aircraft
IPC: B64C13/00
Filed: 1939-05-08
Abstract: 527,549. Aircraft controls. BUGATTI, E. May 8, 1939, No. 13775. Convention date, May 7, 1938. [Class 4] [Also in Group XXIX] An aircraft has means for producing an aerodynamic braking effect substantially without any consequential variation of the lift, the braking effect being brought into action in conjunction with the positioning of other control surfaces. In all the forms described, split flaps at the trailing edges of the wings are employed, the flaps moving in unison under control of an air speed responsive device or in conjunction with adjustments of the elevator or a manually actuated cam to suit various flight conditions, the flaps being splayed to produce a braking effect whenever the angular adjustment of the flaps exceeds a predetermined amount. Means are provided for preventing the splaying of the flaps except when the engine is stopped or idling, and for actuating the flaps in the appropriate direction when the landing wheel brakes are applied. In all cases, fluid pressure servomotors are employed for actuating the flaps. Flattening out for landing may automatically initiate the lowering of the landing wheels. Flaps 2, 3 have arms 4, 5 connected to a lever 8 on a shaft 9, Fig. 9, which is jointed at 10 to a shaft 11 having a lever 11 connected to the piston rod of a servomotor S. The pilot valve of the servomotor is controlled by a piston 13 in a cylinder 12, the piston being acted upon by a spring 16 and reduced air pressure derived from a Venturi tube 15. Increase of speed above the normal will consequently raise the flaps and decrease of speed will lower them. A valve 27 enables the cylinder 12 to be put into communication with the engine induction pipe 28, when the wheel brakes are actuated, so as to cause the flaps to rise, or, alternatively, fluid braking pressure may be admitted to the opposite end of the cylinder. Whenever the flaps move in either direction beyond predetermined limits, a cam 23 on the shaft 11 acts through the linkage shown upon the pilot valve of a servomotor S<1> so as to cause the shaft 9 to be swung back and by pulling on rods 6, 7 cause the flaps to be splayed apart. Fluid pressure for controlling the servomotors is supplied by a pump 33, and a valve 25 connected to the engine' throttle shuts off the supply to the servomotor S' whenever the engine throttle is open. Each servomotor comprises a piston 29 having a rod 31 bored to guide a valve 32. An inlet passage 36 communicates with grooves 37, 38 in the valve, and an exhaust passage 39 with a groove 40. These grooves co-operate with ports 34, 35 on opposite sides of the piston to control the movement of the piston. Alternatively, the servomotors may each comprise a piston in a cylinder subjected on one of its faces to the pressure of a fluid escaping through a calibrated orifice, the pilot valve being a valve in the feed circuit of the cylinder. Fig. 10 shows a modification in which the lever 8 is carried by an arm 41 on a sleeve 42 rotatable about the shaft 11 by the servomotor S<1>. The shaft 11 has an arm 43 connected by a link 44 to a third arm on the lever 8. In this form a cam 47 moved by the elevator control mechanism acts on an arm 45 to control the servomotor S, the arm 45 being connected also to the rod 50 of a piston in a cylinder to which braking pressure fluid is admitted, when the wheel brakes are applied, in order to move the arm 45 to actuate the servomotor S in a direction to raise the flaps. An extension of the arm 5 co-operates with an electric contact to start an electromotor 59 to lower the landing wheel whenever the flap 3 is depressed an unusual amount such as occurs when the machine is flattened out prior to landing. Fig. 11 shows a modification in which cams 53, 54 on a shaft 55 connected to the pilot's control lever 56 actuate the shaft 11 and sleeve 42 corresponding to the similar parts shown in Fig. 10. The servomotors are, however, arranged in the links 6, 7. The sleeve 42 is immobilized when the engine is running by admitting pressure fluid to a cylinder containing a piston 57. The Specification as open to inspection under Sect. 91, 4 comprises also the following subjectmatter which does not occur in the Specification as accepted. In a modification of the arrangement shown in Fig. 11, the shaft 55 is divided, the cam 54 being controlled in accordance with the speed of the aeroplane through connections to the elevator or a Venturi tube so that the braking means is independent of the lift-varying means. Specification 527,550 is referred to.