GB942329A - Propulsion unit for aircraft - Google Patents

Abstract

942,329. Vertical lift aircraft. ROLLS-ROYCE Ltd. Dec. 1, 1961 [Dec. 8, 1960], No. 42329/60. Heading B7G. [Also in Division F1] A vertical lift gas turbine engine comprises in flow series a compressor, combustion equipment, a turbine and a thrust nozzle, a bleed conduit being arranged upstream of the combustion equipment and extending externally of the engine, means being provided for supplying the bleed conduit with a proportion of the air compressed by the compressor, and further means being provided for varying the effective area of the thrust nozzle so as to vary the speed of the turbine and compressor and so the amount of air supplied to the bleed conduit. The embodiment is described with reference to an aircraft comprising a group of six vertical lift engines, two of which are shown in Fig. 2, each comprising a compressor 16, combustion equipment 17, a turbine 18, a jet pipe 20 and a thrust nozzle 21, a proportion of air compressed by the compressor passing through a bleed conduit 22 to a manifold 23, the air flow being controlled by a valve 53. The air from the manifold 23 passes to nozzles disposed at the forward and after ends of the aircraft fuselage and at the wing tips for aircraft control purposes. - The thrust nozzle 21 of each engine has an aperture 30 which is normally closed by a flap 31 pivotally mounted at 34, the flap being disposed within a housing 32, Fig. 3, which has an opening 33, so that when the flap is swung outwardly the effective nozzle area is increased. A link member 35 is pivotally connected at one end to the flap 31 and at its other end to the end of the piston rod 37, the piston 38 of which is disposed within a cylinder 40 which is pivotally mounted at 41, the piston being loaded towards the left by a spring 42. An operating link 43 comprising two arms 44, 45 (see Fig. 3) is connected to the pivotal point 36 of the link 35 and piston rod 37, the opposite ends of the arms 44, 45 carrying studs 46 which engage in slots 47 in track members 48, the track members being mounted for pivotal movement at 50. The track members may be rotated through an arc by means of a cable 51 which is connected to a valve operating lever 52, the lever controlling the valve 53 disposed in the bleed conduit 22. All the valve operating levers 52 are connected by a common linkage 54 to a manually operable lever 55. When the track members 48 are in the position shown in Fig. 4, the flaps 31 cannot be opened, but when the members 48 are moved in a clockwise direction as shown in Fig. 5, the spring 42 acts to open the flap as shown in Fig. 6. The flaps 31 are normally closed and the valves 53 are in such a position that say 3 to 5% of the air from the compressors passes to the bleed conduit 22 for aircraft control purposes. In the event of failure of one or more of the lift engines, the lever 55 is operated so as to effect opening of the flaps 31, the increase in nozzle area resulting in reduced back pressure on the turbines which therefore overspeed whereby the amount of air supplied to the bleed conduits will increase to say 12% of the output of the compressors. The cables 51 could be moved by means responsive to an engine failure instead of manually.