GB2076060A - Liquid propellant rocket - Google Patents

Abstract

Each rocket stage 12, 14, e.g. of a missile, comprises a fuel tank module 18 having a central axial passage 42 which receives an engine module 20, detachable connection being made at the front end of the latter for the flow of fuel thereto. In the tank module 18 there is an oxidizer tank 22 in front of a fuel tank 24. The rear portion 40 of passage 42 flares out to accommodate the rocket engine 46 itself which is connected by a gimbal joint 52 to the combustion chamber 48 fed from the tanks by a pump unit 50. <IMAGE>

Description

SPECIFICATION Liquid propellant rocket This invention concerns a liquid propellant rocket, eg a missile.

Currently available liquid propellant rockets applied to intermediatre range ballistic missiles show advantages over solid propellant systems in terms of range, performance, and weight. Design of specific systems is based upon parametric data optimization and data developed for air-launched and ground-launched ballistic missile systems.

Both pressure-fed and pump-fed liquid propellant systems have been studied for a variety of propellant combinations, payload requirements, launch constraints and missile ranges. Pump-fed systems have been found to be lighter and of higher performance than equivalent solid propellant systems for both ground-launched and air-launched missiles. Pump-fed systems have also been found to be smaller and higher performing for the same range and payload requirements than the comparable pressure-fed missiles. It has been determined that a combined lighter-weight tank structure and rocket engine could be used with a pump-fed liquid propellant system to yield better packaging within the missile's gross weight limit for pump-fed systems.Preliminary conclusions have indicated that a two-stage missile using pumps optimized for each stage and a sfngle- stage missile using higher energy propellants can both provide the maximum range and payload capability. Launcher constraints, missile flexibility, life-cycle costs, maintainability, and technology risk have been evaluated. Studies have been conducted for liquid and gelled propellant propulsion systems, mixed (solid/liquid) stage missiles, pressurization systems, tank structure and configuration, turbopumps, and turbine drive systems. It has been concluded that the pump-fed liquid propulsion system is a variable concept for low-cost intermediate range ballistic missiles,, eg air-launched or ground-launched missiles designed for maximum range of manoeuvring capability.Missile range and capability are a function of propulsion system design, missile drag and propellant carry weight. It is an object of this invention to provide a rocket with a compact construction whereby a missile can have a high packaging factor and a decreased length for a given volume of propellant.

According to the present invention, there is provided a liquid propellant rocket having at least one stage comprising a tank module for containing propellant, wherein the tank module comprises a forward tank and an aft tank, each tank being defined by an outer shell structure, forward and aft bulkheads, and an axially oriented open tubular structure forming the inner wall of the tank module; and an engine module oriented housed within the tubular structure of the tank module.

Propellant volume capacity is increased by denser packaging through a conformal tank shape around the engine structure resulting in shorter missile length. This results in increased range and/or manoeuvring capability and is applicable to both pump and pressure-fed propulsion systems.

The rocket may include such items as conformal tank forward and aft bulkheads for integral packaging of the engine into the tank, minimal diameter turbopumps, gimbaling and thrust reaction tube, integral pressurization and tank support packaging and no external lines and cables. The modules are independent during fabrication but interface quickly with each other on the final booster to provide positive propellant containment and decreased maintenance care during field use. The concentric design of these propulsion modules permits denser packaging and higher propellant loading which, in turn, results in an increase in missile range and/or manoeuvring capability.

The invention will be described in more detail by way of example, with reference to the accompanying drawings, in which: The Figure is an exploded schematic perspective view of a two-stage missile having a liquid rocket propulsion system.

In the Figure, a rocket missile 10 has two stages, wherein the first stage is the booster stage 12 and the second stage is the sustainer stage 14, and wherein each stage comprises a liquid propellant system 16.

The system 1 6 comprises a tank module 18 for containing the propellant, and an engine module 20 for providing thrust. Tank module 1 8 includes an oxidizer tank 22 and a fuel tank 24 wherein the outer shell structure 26 of tanks 22 and 24 comprise wall portion 28 of the missile chamber 30. The oxidizer tank 22 is preferably forward of the fuel tank 24 and comprises a forward bulkhead 32, which also serves as the forward bulkhead 34 of the missile chamber 30, and an aft bulkhead 36. The fuel tank 24 similarly comprises a forward bulkhead 38, which is coincident with the oxidizer tank after bulkhead 36 and an aft bulkhead 40 which is conformal to the engine 46.

Axially oriented through both the oxidizer tank 22 and fuel tank 24 is a tubular structure 42 which forms the inner wall 44 of the tank module 18.

Although it is preferred that the oxidizer and fuel tank outer shell structure 26 be integral with wall the portion 28 of missile chamber 30, the design may require separate oxidizer and fuel tanks housed inside the wall 28 of missile chamber,30.

The engine module 20 is designed so that it not only fits within the tubular structure 42, but in its preferred mode serves as a support structure for the inner wall 44. It should be noted that although the components of engine module 20 are basically known the arrangement which permits them to be housed within tubular structure 42 and preferably detachably connected to the forward bulkhead 32 of oxidizer tank 22 is novel. These components include the engine 46, means for pressurizing and expelling the propellant such as a gas generator 48, pumps 50, and a gimbal 52.

Both circular and non-circular external crosssections were examined for ground and airlauched liquid propellant missiles 10 to achieve maximum packaging density and'propellant carrying capability. In general, it is desirable to maximize the number of missiles that can be carried within a given launcher cross-section up to the maximum gross weight limit of the launcher.

Circular shapes were evaluated for both pressure- and pump-fed systems. Non-circular shapes were also evaluated as they appeared to be more volume efficient. In general, noncircular shapes were used where tank pressures could be minimized to reduce structural weights.

Noncircular shapes are attractive for a pump-fed system since lower internal tank pressures are used, thus limiting the deflections of noncircular shells.

A packaging factor of 1.0 (all volume occupied by propellant and components so that no freevolume exists) was selected as a design objective.

The approach was to minimize the free space not utilized for propulsion system components, by relocation of the components and by reducing the size of the components. This goal was approached by changing from a tank-end packaging to the centre-tube packaging concept shown in the Figure, and configuring the aft fuel tank bulkhead 40 so that the engine module 20 and its gimbal system 52 would be partially buried to minimize the volume loss. This was determined to be an effective way to maximize the propellant volume for a give missile.

Pressurization and feed system components, and lines were located within the small centre tube 42 and within the contoured tank bulkhead 40. Since the oxidizer normally has higher vapour pressure than the fuel, it is preferred that the fuel be stored in the tank 24 with the contoured or conformed bulkhead 40 while the oxidizer is stored in tank 22 with the elliptical bulkheads 32 and 36 to minimize the tank/stage wall thicknesses and thus its weight. Interstage structure 54 is minimized by functioning only to join the bulkead 34 of booster stage 12 with the aft bulkhead 40' which is conformal to the engine 46' of sustainer stage 14. Increased range was achieved through the increase in propellant volume carried within the conformal tankage 24 and 24' of the booster and sustainer stages, respectively.

The rocket engine 46 and gas generator 48 are the largest components of the engine module 20 and therefore considerabe time was expended in designing the packaging of these components to minimize the propellant volume lost. The location of the rocket engine 46, its gimbal angle and gimbal mechanism 52, as well as the large diameter line and controls, were packaged within the conformal tank head 40 and centre tube 42.

The gas generator 48 used or tank pressurization and/or turbine drive gas was packaged within the tank centrebody 42, and its dimensions were determined by the amount of pressurant gas and turbine drive gas required.

Lines and fittings connecting the gas generator 48 and rocket engine 46 to the propellant tank module 1 8 were constructed so that easy assembly-could be made during the fabrication.

Claims (8)

1. A liquid propellant rocket having at least one stage comprising a tank module for containing propellant, wherein the tank module comprises a forward tank and an aft tank, each tank being defined by an outer shell structure, forward and aft bulkheads, and an axially oriented open tubular structure forming the inner wall of the tank module; and an engine module housed within the tubular structure of the tank module.

2. A rocket according to claim 1, wherein the engine module services as a support element for the inner wall of the tank module.

3. A rocket according to claim 1 or 2, wherein the engine module is detachably connected to the forward bulkhead of the forward tank.

4. A rocket according to claim 1, 2 or 3, wherein the aft bulkhead of the aft tank is shaped to complement the shape of the engine module.

5. A rocket according to any of claims 1 to 4, wherein the forward tank is an oxidizer tank and the aft tank is a fuel tank.

6. A liquid propellant rocket stage comprising a tank module with a central, axial passage which flares out at the rear end of the stage, and an engine module housed within the passage.

7. A liquid propellant rocket stage according to claim 6, wherein the engine module is detachably coupled to the tank module at the front end of the engine module by means providing for flow of propellant from the tank module to the engine module.

8. A liquid propellant rocket substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.