WO2006056742A1

WO2006056742A1 - Satellite launch system

Info

Publication number: WO2006056742A1
Application number: PCT/GB2005/004347
Authority: WO
Inventors: Kenneth John England
Original assignee: Emat Limited
Priority date: 2004-11-24
Filing date: 2005-11-10
Publication date: 2006-06-01
Also published as: GB0425874D0

Abstract

A satellite launch system (2) is disclosed. The launch system comprises an open ended launch tube (4) for receiving a vehicle (10), and steam generators (6) for injecting steam (5) into the launch tube for accelerating the vehicle towards the open end to launch the vehicle at supersonic speed.

Description

SATELLITE LAUNCH SYSTEM

The present invention relates to a method and apparatus for launching a high speed airborne vehicle, and- relates particularly, but not exclusively, to a method and apparatus for launching satellites.

There is a large demand for orbital satellites, primarily for telecommunications applications, and existing satellite launching systems generally use multi-stage rockets. Multi-stage rockets, although generally effective for launching satellites, suffer from the drawback that they are inefficient and expensive, the first stage rocket generally comprising up to 90% of a rocket's take off weight, while providing little more than 10% of the final payload energy.

It has been proposed to replace the first rocket stage of a multi-stage rocket assembly by wing borne aircraft having engines using atmospheric air as oxidant, avoiding the need to carry the oxidant for the first stage of the rocket. However, such designs suffer from the drawback that the aircraft are required to take off conventionally, fly sub-sonically, make the transition to supersonic and hypersonic flight, decelerate and land again conventionally. This significantly adds to the complexity and cost of designing the system.

Preferred embodiments of the present invention seek to overcome the above disadvantages of the prior art .

According to an aspect of the present invention, there is provided an orbital vehicle launching system comprising:-

a conduit for receiving a payload and having at least one open end; and fluid generator means for introducing propulsion fluid into said conduit at at least one location along said conduit for accelerating the payload towards at least one said open end to launch said payload at supersonic speed.

By introducing propulsion fluid into the conduit at at least one location along the conduit, this provides the advantage of enabling a vehicle to be accelerated along the conduit in a controlled manner. By launching the payload at supersonic speed, this provides the advantage of significantly reducing the complexity of the design of the system, since simpler engines of the ramjet type can be used to propel the payload subsequently to it exiting the end of the conduit. This in turn reduces the cost of launching satellites compared with multi stage rockets of the conventional type.

The fluid may include steam.

This provides the advantage that the fluid can be generated relatively inexpensively and in a controlled manner.

The fluid may be introduced at a plurality of locations along said conduit.

This provides the advantage of enabling the speed of the payload and the efficiency of operation of the system to be more easily controlled.

The fluid generator means may be adapted to introduce hydrogen, oxygen and water to produce superheated steam at at least one location along said conduit.

The fluid may include a mixture of steam and hydrogen. This provides the advantage of increasing the sonic velocity of the fluid in the conduit, which in turn increases the launch velocity of the vehicle.

According to another aspect of the present invention, there is provided a method of launching an orbital vehicle, the method comprising: -

accelerating an orbital vehicle having a ramjet engine and at least one rocket stage during a first phase along a conduit having at least one open end by means of fluid propulsion, such that the vehicle exits from an open end of the conduit at supersonic speed;

accelerating the vehicle by means of the ramjet engine in a second phase, subsequent to said first phase; and

accelerating the vehicle by means of at least one said rocket stage in a third phase, subsequent to said second phase.

This provides the advantage of significantly reducing the cost and complexity of the design of the system by accelerating the vehicle in the subsonic region by means of fluid flow along the conduit.

The method may further comprise the step of introducing the fluid at a plurality of locations along the conduit.

The method may further comprise the step of housing the vehicle in a protective housing in the conduit .

The method may further comprise the step of generating said fluid.

The fluid may include steam. The step of generating said fluid may comprise introducing hydrogen, oxygen and water to produce superheated steam at at least one location along the conduit.

The fluid may include a mixture of steam and hydrogen.

A preferred embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawing, in which: -

Figure 1 is a schematic representation of an orbital vehicle launching system embodying the present invention;

Figure 2 is a schematic cross sectional view of an inlet to a steam generator of the system of Figure 1; and

Figure 3 is a schematic perspective view of a vehicle to be launched by means of the system of Figure 1.

Referring to Figure 1 a satellite vehicle launch system 2 comprises an open ended launch tube 4 in the form of a pipeline, typically of length greater than 1700m. A series of steam generators 6 (of which only one is shown in Figure 1 for reasons of clarity) is connected to inlets 8 along the launcher tube 4 for injecting steam 5 into the tube 4 to propel a vehicle 10 carrying a payload such as a satellite along the tube 4 for launching at supersonic speed from the open end of the tube 4. The tube 4 is typically inclined at an angle of 1 in 10 to 1 in 5 to the horizontal.

Each of the steam generators 6 comprises a water supply 12, a hydrogen supply 14 and an oxygen supply 16 to generate medium pressure superheated steam 5 for injection into the launcher tube 4.

As shown in greater detail in Figure 2, each steam generator 6 includes a vessel 7 of generally circular transverse cross section and having a combustion chamber 18 at one end. Hydrogen and oxygen are supplied to the combustion chamber 18 from hydrogen supply 14 and oxygen supply 16 via conduits 15, 17 respectively in suitable proportions to enable stable combustion.

An annular arrangement of nozzles 20 is provided around the outlet of combustion chamber 18, and water is supplied from water supply 12 via conduit 13 to the nozzles 20 to inject water as a spray of droplets at high velocity axially along the vessel 7. The heat generated by combustion in combustion chamber 18 evaporates and superheats the droplets . A further annular arrangement of nozzles 22 is provided radially outwardly of nozzles 20, to enable further water droplets to be injected.

The supply of water along conduit 13 is matched to that of hydrogen and oxygen along conduits 15, 17 respectively in such a ratio that superheated steam at the desired temperature is produced. A long mixing chamber 24 is provided to enable the evaporation and superheating process to take place, and for turbulent mixing to produce a generally uniform steam temperature. The skin of vessel 7 is cooled by means of the water supplied to the nozzles 20, 22.

Referring now to Figure 3, the- satellite vehicle 10 carries a payload 38 such as a satellite, one or more rocket stages 40, and an annular arrangement of ramjet engines 30, the entire vehicle 10 being encased within a removable shell (not shown) , preferably in the form of a pair of clamshell halves. The removable shell is designed to be discarded by the vehicle 10 when the vehicle leaves the open end of the tube 4. The vehicle 10 is generally in the form of a long cylinder 26, having diameter about half that of the launch tube 4, a pointed nosecone 28, and stub wings 32. The cylinder 26 contains fuel tanks 34 for supplying the ramjet engines 30, and suitable control apparatus 36 for controlling the vehicle 10 is contained within the nosecone 28.

The operation of the system shown in Figure 1 will now be described.

The introduction of hydrogen, oxygen and water into the steam generators generates medium pressure superheated steam 5, which accelerates the vehicle 10 along the tube 4 in a first stage of operation until it leaves the open end of the tube 4 at a speed of about Mach 1.7. At this stage, the shell encasing the vehicle is discarded, the vehicle 10 becomes airborne, and the ramjet engines 30 are ignited in a second stage, using atmospheric air as a fuel burning oxidant to accelerate the vehicle 10 further, up to a speed of about Mach 8. The rocket stage 40 of the vehicle 10 is then ignited in a third stage to further accelerate the vehicle 10 into orbit.

It is found that by accelerating the vehicle by means of medium pressure fluid to supersonic speeds at which a ramjet using atmospheric air rather than onboard stored oxygen as an oxidant can be used, the fuel consumption of the vehicle is low compared with a conventional rocket, the thrust being about 18kN per kilogram per second fuel burn, as opposed to about 2.5kN per kilogram per second fuel burn for a conventional rocket. This significantly simplifies the design and reduces the cost of the system compared with conventional satellite launching systems.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. For example, the proportion of hydrogen introduced into the launch tube 4 may be increased. This produces a mixture of steam and hydrogen in the launch tube 4, which has a higher sonic velocity than steam. This provides the advantage of increasing the launch velocity of the vehicle 10.

Claims

1. An orbital vehicle launching system comprising: -

a conduit for receiving a payload and having at least one open end; and

fluid generator means for introducing propulsion fluid into said conduit at at least one location along said conduit for accelerating the payload towards at least one said open end to launch said payload at supersonic speed.

2. A system according to claim 1, wherein the fluid includes steam.

3. A system according to claim 2, wherein the fluid generator means is adapted to introduce hydrogen, oxygen and water to produce superheated steam at at least one location along said conduit.

4. A system according to claim 2 or 3, wherein the fluid includes a mixture of steam and hydrogen.

5. A system according to any one of the preceding claims, wherein the fluid is introduced at a plurality of locations along said conduit.

6. An orbital vehicle launching system substantially as hereinbefore described with reference to the accompanying drawings .

7. A method of launching an orbital vehicle, the method comprising: - accelerating an orbital vehicle having a ramjet engine and at least one rocket stage during a first phase along a conduit having at least one open end by means of fluid propulsion, such that the vehicle exits from an open end of the conduit at supersonic speed;

accelerating the vehicle by means of the ramjet engine in a second' phase, subsequent to said first phase; and

8. A method according to claim 7, further comprising the step of introducing the fluid at a plurality of locations along the conduit.

9. A method according to claim 7 or 8, further comprise the step of housing the vehicle in a protective housing in the conduit.

10. A method according to any one of claims 7 to 9, further comprising the step of generating said fluid.

11. A method according to any one of claims 7 to 10, wherein the fluid includes steam.

12. A method according to claim 11, wherein the step of generating said fluid comprises introducing hydrogen, oxygen and water to produce superheated steam at at least one location along the conduit.

13. A method according to claim 11 or 12, wherein the fluid includes a mixture of steam and hydrogen.

14. A method of launching an orbital vehicle, the method substantially as hereinbefore described with reference to the accompanying drawings .