Control apparatus e.g. for controlling movable parts of a supersonic intake

1,026,968. Fluid-pressure servomotor systems. ROLLS-ROYCE Ltd. Dec. 17,1964 [Dec. 24,1963], No. 51018/63. Heading G3P. [Also in Division F1 A supersonic intake of a gas turbine engine is provided with ramp parts, movable by a common ram to vary the effective area of the throat and also movable into and out of a position in which there is a gap between them through which a throat bleed may be taken. The lower surface of the intake is provided with a dump flap and a spill flap, each actuated by a separate ram, the dump flap being selectively pivotable about its leading or trailing edge while the spill flap is only pivotable about its leading edge. During supersonic flight, the ramp parts are positioned to focus the three shock waves and the dump and spill flaps match the flow throught the intake with that through the engine, the dump flap being used as a coarse control and the spill flap as a fine control. The dump flap is pivoted about its trailing edge for speeds below Mach 0.5 5 to provide extra flow, at speeds between Mach 0. 5 and Mach 1. 6 the dump flap is closed and the pivot is moved to the leading edge and at speeds between Mach 1. 6 and Mach 2.2 th dump flap is opened about the leading edge pivot and the dump and spill flaps are positioned to maintain the final shock wave in thedesired position. The system for controlling the ramps and flaps comprises a lever 55, Fig. 3 (not shown) subjected to forces responsive to pressures in chambers 50, 59 which pressures act on evacuated bellows 51, 61,fixed to levers 53, 63 which act on the lever 55. The lever 55 controls leakage of fluid from a conduit 67 fed from a supply 41 through restrictor 71 and cylinder 70. A piston 73 in the cylinder 70 has differential areas 74, 75, the smaller area 74 being subject to the supply pressure fed through passage 76. The piston 73 is thus moved with changes of pressure in conduit 76 under the control of the lever 55 and in so doing moves the ramps through a lever 82 and link 84 and acts through a cam 113 and lever 115 to move a pivot 57 of the lever 55 to provide a feedback. The pressure Ps fed to chamber 59 is measured by a forwardly facing pilot tube in the air intake and the pressure p L in chamber 50 is the static pressure in the intake. The pivot 57 is thus positioned in response to the quotient Ps/L which is the value of the local Mach number at the air intake. The lever 82 is carried by a movable pivot 85 which is normally in the position shown in response to pres