Air is sucked from the boundary layer at the rear of an aircraft surface through apertures connected to an air compressor delivering to a jet propulsion expansion nozzle and may comprise the whole of the airflow through the nozzle or alternatively air from in front of the aircraft may also be passed through the compressor, or through some stages only of a multi‐stage compressor. All or part of the air may be heated by fuel injected through combustion nozzles, and the compressor may be driven by a gas turbine on the same shaft or by a reciprocating engine. The combustion air may be preheated by a heat‐exchanger in the exhaust. The jet nozzle may be the sole propulsive means or an airscrew may be mounted forwardly on the compressor shaft. Slots for intake of boundary layer air may be provided at the points at which the boundary layer tends to break away and may be formed as divergent channels or may comprise merely a scries of holes in the aircraft surface. A scries of such slots may be provided with means by which selected slots only are in operation at any given time, and a pitot tube projecting into the boundary layer in front of a slot may be employed to indicate the condition of the boundary layer before that slot. In landing air may be ejected through supplementary nozzles directed forwardly and downwardly to provide aerodynamic braking. The air may be passed for cooling a radiator mounted in the wing or fuselage. Air taken in forwardly of the aircraft may be compressed by a compressor in the fuselage and then distributed, after heating by fuel injection nozzles, to jet tubes in nacelles in the wing through which also passes the boundary layer air As shown in FIG. 9, air extracted at the trailing edges of the wing of an aircraft passes forwardly through a nacelle and through the first stage CI of a compressor. Part then flows directly to a propulsion nozzle at the rear of the nacelle while part passes through a further stage C2 to a combustion chamber fitted with combustion nozzles ch and through a gas turbine T and heat exchanger E, which heats air bypassing the combustion chamber and turbine, to the propulsion nozzle. The turbine T drives the compressor CI, C2 and an airscrew. In FIG. 11, air is passed from slots 1 in the wings through ducts 2 to a central compressor 4 and thence to a reaction nozzle 6. The compressor 4 is driven by a reciprocating motor 5 which also drives an airscrew 3. In FIG. 12, air from slots 7 in the wings passes through compressors 8 in nacelles in the wings and thence to a reaction nozzle 14. The compressor 8 is driven by a turbine 9 supplied through ducts 12 with air admitted centrally at the nose of the aircraft, compressed by a compressor 10, driven by a reciprocating motor 11, and heated by fuel injection nozzles 13. The exhaust from the turbine 9 is to the jet 14. In FIG. 13, air entering a wing 15 through slots 16, 17 passes through the wing spar 18. to the first stage 19 of a compressor in a nacelle beneath the wing. Part then flows by an annular passage 19a to a propulsion nozzle 20. Part passes through a second stage 21 of the compressor to a combustion chamber 22 fitted with combustion nozzles and through a gas turbine 23 to the propulsion nozzle 20. The turbine 23 drives a propeller 24. Specification 512,064 is referred to.
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