Jet turbine engines used by aeromodellers suffer a number of inconveniences.

They must be run up initially using compressed air to rotate the turbine. The injectors must be preheated usually by propane. The fuel is supplied by an electric fuel pump which requires the aircraft to carry a speed controller and battery to control engine speed. Some conventional engines require oil to be mixed with the fuel so that when the engine is shut down, and still very hot, there is no lubrication. Others carry a separate oil supply with its inherent penalties of weight and complexity.

Different aspects of the invention address respective ones of these inconveniences.

In accordance with one aspect of the invention, there is provided a turbine engine, having a compressor towards the front and a turbine towards the rear and connected by a shaft, an electric motor and/or generator having a rotor mounted on the shaft preferably between the compressor and the turbine. This arrangement removes the need for a compressed air supply. A small starter battery is suitable to run up a model engine and, with any necessary controller, is convenient to carry or may be mounted on board, if desired. Once the engine is running, the starter battery and/or the receiver battery may be charged from the generator.

In order to keep the area in which the electric motor and/or generator is mounted between the compressor and the turbine relatively cool, the combustion chamber is preferably located behind the turbine, a first passage connecting an outlet of the compressor to an inlet of the combustion chamber, and a second passage connecting the outlet of the combustion chamber to an inlet of the turbine.

The armature may rotate. However, in order to simplify the construction, the electric motor and/or generator preferably has a static armature.

In one form, the rotor comprises at least one permanent magnet, which may be mounted on an impeller of the compressor.

In an alternative, the rotor is in the form of a disc mounted directly on the shaft.

The disc may be a conducting metal, e. g. copper, so that the motor and/or generator is in the form of an induction motor and/or generator.

In accordance with another aspect of the invention there is provided a turbine engine, having a compressor towards the front, a turbine towards the rear and connected to the compressor by a shaft, and a fuel pump having a rotor mounted on the shaft for rotation therewith. This arrangement removes the need for a battery and speed controller to be carried by the aircraft. The speed of the engine can be controlled by a valve and a servo. The servo can be powered by the aircraft's receiver battery.

The rotor preferably has a central inlet and radially extending passages, the rotor being contained by a casing providing a fuel outlet.

The fuel outlet is preferably connected via a fuel delivery passage to one or more injectors directed into the combustion chamber, a bypass valve also being connected to the fuel delivery passage to control flow rate of fuel delivered to the injector (s).

Preferably, the fuel pump also delivers fuel via a regulator valve to cool one or more bearings on which the shaft is mounted.

In accordance with another aspect of the invention, there is provided a turbine engine, having a compressor towards the front and a turbine towards the rear and connected by a shaft, the compressor and the turbine being connected by a combustion chamber into which fuel is injected and burnt, at least one injector for injecting fuel into the combustion chamber, which injector has a helical passage to impart vortex motion to fuel injected into the chamber. The vortex motion facilitates the injected fuel dividing sufficiently finely, e. g. to a vapour, that ignition can be obtained without preheating.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal cross section through a micro jet turbine engine having a fuel pump embodying an aspect of the invention; Figure 2 is an enlarged cross section of the fuel pump; Figure 3 is a transverse cross section of the fuel pump; Figure 4 is a longitudinal cross section of part of a jet turbine engine having an alternative fuel pump embodying an aspect of the invention, and an electric starter motor and/or generator embodying another aspect of the invention; Figure 5 is a sectional detail showing an alternative electric starter motor and/or generator; Figure 6 is a sectional detail showing another alternative starter motor and/or generator; Figure 7 is a detail of an injector of the engine of Figure 1; and Figure 8 is a schematic diagram of the fuel system.

Referring to the drawings, the jet turbine engine 1 has a compressor 2 and a turbine 4 both mounted on and for rotation with a hollow shaft 6. The shaft 6 is mounted for rotation in bearings 8 contained by a casing 10. The casing 10 is mounted on a compressor diffuser 12 by a plate 14 and spacers 16. An external case 18 is connected to the diffuser 12 and defines a passage from an annular outlet 20 of the compressor to a toroidal combustion chamber 22 walls 24 of which are perforated to allow air from the compressor to enter. Fuel is injected into the combustion chamber 22 by a plurality of injectors 26, which extend through the casing 18, and ignited initially by a spark plug 28.

Only one of the injectors is shown in the drawings.

Exhaust gasses from the combustion chamber enter an annular inlet 30 of the turbine 4 and leave via an exhaust 32 which passes through a rear plate 34 of the casing.

In order to supply fuel to the injectors 26, a rotor 36 of a fuel pump 37 is mounted on the shaft 6 for rotation therewith. The pump has a stator 38 within which the rotor rotates. A fuel inlet 40 through the casing 10 communicates through the stator with a central toroidal chamber 42 in the stator. The chamber 42 communicates with a central toroidal chamber 44 in the rotor 36. An annular surface 46 of the rotor is in sealing engagement with an annular surface 48 of the stator. A plurality of backwardly curved radially extending grooves 50 in the annular surface 46 provide radially extending passages through which fuel is urged by centripetal force into a toroidal outlet chamber 52 thence to an outlet 54.

An alternative arrangement is shown in Figure 4 mounted in front of the compressor. In this case the radially extending passages are provided by radial bores 56 in the rotor.

Referring to Figure 8, the pump inlet 40 is connected to a fuel tank 56 via a filter 58. The outlet 54 is connected via a filter 60 to the injectors 26. In order to control the flow to the injectors, a bypass valve 61. The valve is controlled by an electrical servo 64 such as is common in radio controlled models.

In order to cool the bearings 8, especially the rear most since that is closest the hot exhaust, a small amount of fuel is supplied to them via pipes 66 in Figure 4, and via a flow regulator valve 66 and a filter 68 shown in Figure 8. In the arrangement shown in Figure 5, a single pipe 66 is used to inject fuel between the bearings. Fuel injected into the bearings finds its way to the compressor outlet or to the turbine inlet along paths indicated by arrows in Figures 4 and 5. As may be seen, the path from the rear bearing passes behind the turbine which is cooled thereby. In figure 4, the hotter rear bearing abuts a heat conducting disc or cylinder 67, which is mounted on the shaft and which acts as a heat sink. The cylinder is formed with a helical groove 69 in its periphery. This acts to draw fuel through the bearing and thus to cool itself and also the bearing directly.

In the detailed part sections shown in Figures 4,5 and 6, an electric starter motor and/or generator 70 is illustrated.

The motor and/or generator illustrated in Figure 4 has a rotor 70 mounted on and for rotation with the shaft 6. The rotor carries a set of permanent magnets 72 disposed therearound, only two can be seen in Figure 4. A set of printed coils 74 is mounted on a stator 76 disposed in the casing 10. The coil extends into an air gap 78 in the rotor so that a magnetic circuit including the permanent magnets passes through the coils. As a motor, a controller, not shown, supplies AC or electrical pulses to cause the rotor to rotate in synchronism.

In the engine illustrated in Figure 5, the permanent magnets 72 are carried directly by the compressor rotor 2. The stator 76 carrying the coils 74, is mounted outside the casing 10.

In the engine illustrated in Figure 6, the motor and/or generator is an induction type. A conducting (e. g. copper) disc 80 is mounted on. and for rotation with the shaft 6.

The disc extends into an air gap 82 in a laminated core 84 on which windings 74 are located.

An injector 26 is illustrated in Figure 7. The injector has a body 86. Fuel delivered from the fuel pump 37 passes through a passage 88 to a nozzle 90 which is threadedly mounted on the body. The fuel leaves the nozzle under pressure via a jet orifice 92. A section 94 of the passage 88 approaching the orifice 92 is conical and forms a seat for a conical surface 96 of a plug 98 which is urged into sealing engagement with the conical section by a compression spring 100. Spiral grooves 102 in the conical surface 96 of the plug provide spiral passages through which the fuel passes to give a vortex motion to the fuel injected through the orifice 92.