Patent GB-981062-A (GB)
Title: Improvements in jet propulsion power plants
Inventor: POTTER RAYMOND JAMES
IPC: B64D37/20
Filed: 1960-05-11
Abstract: 981,062. Jet propulsion plant. BRISTOL SIDDLEY ENGINES Ltd. May 4, 1961 [May 11, 1960], No. 16665/60. Heading F1J. [Also in Division G3] In jet propulsion power plants means are provided to offset the pressure heads produced by acceleration in e.g. the fuel and hydraulic control systems. Each of the two wing-mounted ram-jet engines 3, of a missile has a pilot fueljet 11 and a main fuel manifold 12 with discharge orifices, the pilot and main combustion chamber being separated by a flame holder 10. In the missile body 1 is a fuel tank 13 and a fuel pump 14 driven by an air turbine 15 receiving ram pressure through ducts 16 and a valve 17 from which lead exhaust and by-pass air-ducts, 19; the pump 14 delivers fuel into pipes 22, 23, the latter opening into a device 24 controlling the valve 17, the device being also subjected to ram pressure from a probe 26, the valve 17 controlling the turbine 15 to maintain these two pressures at a constant ratio. By this means the pressure in pipe 22 is also held constant, which pipe leads to a valve 27 the flow through which is proportional to the pressure thereacross; valve 27 has a number of outlets 29 leading to the main fuel jets, which outlets are controlled by a spring-urged piston 30, the pressure in a chamber 33 at the back of the piston being variable, to enable the missile speed to be regulated. An orifice 32 is provided through the piston 30 and the fuel pressure in chamber 33 is controlled by a further variable orifice 35 connected to a Machmeter 36 where it receives ram pressure from the probe 26 and static pressure from orifices 37 in the probe. Another variable orifice, not shown, may by provided in series or parallel with orifice 35 and made responsive to incidence; the additional orifice may alternatively limit the opening of orifice 35. The valve 30 may be actuated by a fluid other than fuel admitted to chamber 33 through an orifice from a constant pressure pump. Due to the longitudinal spacing between orifice 35 and valve 27 the servo-pressure in the latter differs from that at the orifice 35 by an acceleration induced head; similarly the longitudinal spacing between device 24 and the valve 27 produces an error in the fuel arriving at the valve 27 which (1) alters the position of the piston 30 and (2) changes the pressure drop across the outlets 29. This pressure drop is also changed in the same sense by an acceleration induced head in the pipe leading from the valve 27 to the manifold 12 but since the piston 30 is disposed normal to the direction of flight it is not displaced by this longitudinal accelerations acting on its mass. A return flow pipe 39 is provided from the orifice 35 into the air flow pipes of the two engines forward of the valve 27 and through relief valves 40 which prevents the pipes 39 emptying. Any longitudinal acceleration therefore acts on the liquid in pipes 39 and on the servo-means, fuel metering valve 27 and control device 35 to change the metering orifice area in the sense necessary to compensate for any change in fuel pressure arriving at or leaving the valve 27 due to the acceleration. If the manifold 12 valves 27, 40 and device 24 are arranged in the same transverse plane, the longitudinal accelerations are compensated for without any change in metering orifice area. In a modification, the engines are arranged above and below the plane of the wings and the' effects of pressure heads in the fuel control system due to longitudinal accelerations and accelerations perpendicular to the plane of the wings are compensated for by disposing the pistons 30 in the longitudinal direction and spacing them longitudinally from the control device 24. A separate orifice 35 and pipe 39 is provided for each piston 30, each pipe 39 discharging into the engine opposite to that from which its supply of servo-liquid originates. The valves 27 may be of the rotary type and so rendered insensitive to linear acceleration whereupon the relief valves 40 are moved longitudinally to compensate e.g. for the spacing between valves 27 and the device 24.