Air intakes in aircraft engines

837,497. Jet-propulsion plant. NAPIER & SON Ltd., D. May 28, 1958 [July 3, 1957], No. 21209/57. Class 110 (3). [Also in Groups XXIX and XXXIII] An annular air intake 13, Fig. 1A, for an aircraft engine has has two series of circumferentially spaced flaps arranged in its outer wall to open outwards, the upstream series of flaps 41 being pivoted at their downstream ends and the downstream series 44 at their upstream ends. Hydrogen peroxide is catalytically decomposed in chambers 31, Fig. 1B, to form oxygen-rich steam, and passed to rocket combustion chambers 32 in which paraffin is burnt with some of the oxygen. The combustion gases, still oxygen-rich, drive a turbine 30 and enter an annular combustion chamber 17 together with air taken in through the intake 13 and through the flaps 41. When the flight speed, sensed by pitot orifices 156, 158, Fig. 2, reaches Mach 0.95, an hydraulic servomotor 43 (see Group XXIX), closes the flaps 41. At the same time, the supply of hydrogen peroxide and paraffin to the rocket system is cut off either automatically by means of a Mach meter 34 or manually, and flap valves 36 are opened by means of hydraulic servomotors 38 to allow the air from the intake 13 to pass through a by-pass 35 surrounding the air compressor 15. The engine then operates as a ram jet, and the compressor 15 windmills, a free-wheel 28 allowing it to overrun the stationary turbine 30. Stator blades 39 are adjusted by the servomotors 38 to reduce losses in the compressor during windmilling. During ram-jet operation, the position of a shock wave 182 sensed by means of orifices 150, 152, is stabilized by the flaps 44 which are opened to a varying extent by means of an hydraulic servomotor 47 (see Group XXIX). A bullet 20 is movable by an hydraulic ram 21 controlled by a follow-up servo valve 23.