GB2094240A

GB2094240A - Attitude control systems for rocket powered vehicles

Info

Publication number: GB2094240A
Application number: GB8107539A
Authority: GB
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1981-03-10
Filing date: 1981-03-10
Publication date: 1982-09-15
Also published as: GB2094240B

Abstract

An attitude control system for a rocket powered vehicle has four auxiliary nozzles 22-25 supplied independently of the main rocket thrust nozzle 10 and capable of providing attitude control in pitch, roll, and yaw, due to their orientation. <IMAGE>

Description

SPECIFICATION Attitude control systems for rocket powered vehicles The present invention relates to attitude control systems for rocket powered vehicles such as air to air missiles.

Conventionally, aerodynamic control surfaces are used to control the attitude of rocket powered vehicles. These have the disadvantages that they cause high levels of drag when they are used to provide high rates of change of attitude, and that they lose effectiveness at high altitudes where the air density is low.

Considerable research is therefore being undertaken into alternative attitude control systems. A well-known alternative, known as thrust vector control, relies on varying the direction of the rocket thrust vector relative to the vehicle axis. When large changes of thrust vector direction are required, this involves the use of moving parts in an extremely hot environment. To ensure reliability thrust vector control systems must therefore be carefully engineered and so tend to be expensive. This is particularly true when the overall vehicle guidance system requires the vehicle to be controlled in roll as well as in pitch and yaw.

According to the present invention an attitude control system for a rocket propelled vehicle includes four auxiliary nozzles symmetrically positioned round a longitudinal axis and acting in planes at right angles to a direction of thrust of a main thrust nozzle, each auxiliary nozzle having a propellant supply independent of, and being operable independently of, the other nozzles, the four auxiliary nozzles being capable of providing a substantially chordwise thrust, relative to the longitudinal axis, in each of four directions at right angles to one another, and adjacent auxiliary nozzles being capable of providing thrusts which, when equal, combine to provide a pure pitching or yawing moment to the vehicle.

In one embodiment of the invention the auxiliary nozzles act in two planes axially separated along the vehicle longitudinal axis each plane having two nozzles capable of providing diverging thrusts.

This arrangement allows the vehicle's attitude to be under complete control in yaw, pitch and roll, as will be clear from the following example of the invention, which is described with reference to the accompanying diagrammatic drawings of which, Figure 1 is a side elevation, in section along line 1-1 of Fig. 2, of part of a rocket motor, and Figure 2 is an end elevation, in section along line Il-Il of Fig. 1.

A rocket motor having a longitudinal axis 10 has a first liquid propellant tank 11 annularly contained between an outer skin 1 2 and an inner skin 13, the inner skin 1 3 defining a cylindrical second liquid propellant tank 14.

Propellant supply pipes 1 5 frorn the first propellant tank 11 and 1 6 from the second propellant tank 1 4 pass through an end plate 1 7 to a main combustion chamber 1 8 which terminates in a main thrust nozzle 19.

A motor casing 2Q has four auxiliary combustion chambers 21 (of which two are shown in dotted lines in Fig. 1) passing therethrough and leading to auxiliary nozzles 22, 23, 24 and 25. The nozzles 22 to 25 are directed chordwise relative to the longitudinal axis 10 in planes at right angles to the axis 1 0 and in four directions such that thrusts from the nozzles are at right angles to one another.

Adjacent nozzles, for example nozzles 22 and 23 as illustrated in Fig. 2, are directed so that thrusts therefrom combine in the pitching sense and tend to cancel one another in the rolling sense. As will be clear from Fig. 2, with this arrangement diametrically opposite nozzles, for example nozzles 22 and 25 as illustrated, are directed so that thrusts therefrom combine in the rolling sense and tend to cancel one another in the pitching sense. Two nozzles 22, 23, providing diverging thrusts, lie in one plane and the other two nozzles 24,25, lie in another plane separated axially along the axis 10.

Propellant supply pipes 26, of which two are shown in do'ed lines in Fig. 1, pass through control valves 27 to each combustion chamber 21 from the first propellant tank 11.

Propellant supply pipes 28, of which two are shown in dotted lines in Fig. 1, pass through control valves 29 to each combustion chamber 21 from the second propellant tank 14.

Each auxiliary combustion chamber 21 therefore has its own fuel supply independantly controllable by valves 27, 29.

In operation a vehicle including the rocket motor is propelled by combustion of propellant in the main combustion chamber 18. A guidance system (not shown) senses attitude changes required to maintain a desired trajectory, and operates valves 27 and 29 to allow propellant to enter one or more of the auxiliary combustion chambers 21. Thrust from the associated auxiliary nozzle or nozzles will then effect an appropriate attitude change.

It will be realised that whilst propellant can be supplied independently to each auxiliary combustion chamber 21, in practice it will usually be supplied to at least two chambers 21 at once. For example, to provide a pure pitching moment about a horizontal axis of the vehicle, with the vehicle orientated as illustrated in Fig. 2, synchronised thrusts must be provided through nozzles 22, 24 or through nozales 23, 25.

Propellants used in liquid fuel propelled rockets usually comprise a fuel and an oxidant such that spontaneous combustion occurs on mixing, so no ignition system has been illustrated or described. Propellant delivery systems and control valves, and combustion chambers, are well-known in the art, and, as such, do not constitute part of the invention.

They have therefore not been described in detail, and have been illustrated only diagrammatically.

Whilst both main 18 and auxiliary 21 combustion chambers have been described and illustrated as receiving propellant supplies from the same tanks 11, 14, it may in practice prove advisable to have separate tanks for the main and for the auxiliary chambers. Alternatively it may prove advantageous to maintain a reservoir for the auxiliary combustion chambers to allow directional control to be maintained for a period after the main combustion chamber 1 8 has ceased to operate. It will be realised that many alternative propellant tank arrangements, for example tandem tanks, can be used with the invention.

Claims

1. An attitude control system for a rocket propelled vehicle including four auxiliary nozzles symmetrically positioned round a longitudinal axis and acting in planes at right angles to a direction of thrust of a main thrust nozzle, each auxiliary nozzle having a propellant supply independent of, and being operable independently of, the other nozzles, the four auxiliary nozzles being capable of providing a substantially chordwise thrust, relative to the longitudinal axis, in each of four directions at right angles to one another, and adjacent auxiliary nozzles being capable of providing thrusts which, when equal, combine to provide a pure pitching or yawing moment to the vehicle.

2. An attitude control system as claimed in claim 1 wherein the auxiliary nozzles act in two planes axially separated along the vehicle longitudinal axis each plane having two nozzles capable of providing diverging thrusts.

3. An attitude control system substantially as herein described with reference to the accompanying drawings.

4. A rocket having an attitude control system as claimed in any one of claims 1 to 3.

5. A rocket as claimed in claim 4 wherein all the nozzles receive propellant from a common source.

6. A rocket as claimed in claim 4 having separate propellant sources for the main thrust nozzle and for the four auxiliary nozzles.

7. A rocket as claimed in claim 5,6 or 7 wherein the auxiliary nozzles can be supplied with propellant for longer than the main thrust nozzle.