GB2051319A

GB2051319A - Rockets

Info

Publication number: GB2051319A
Application number: GB7939641A
Authority: GB
Original assignee: Baj Vickers Ltd
Current assignee: Baj Vickers Ltd
Priority date: 1979-11-15
Filing date: 1979-11-15
Publication date: 1981-01-14
Also published as: GB2051319B

Abstract

A rocket comprising a forward section (1) and a separable rearward section (3) housing the rocket motor includes a drag inducing element such as a parachute or balloon (8) attached to the forward end of the rear section. There is a timer set to deploy the drag inducing element a predetermined time after separation of the forward and rear sections. Where the drag inducing element is a balloon, it may be inflated by a pressurized gas reservoir or from ram air admitted through a weather-cocking inlet nozzle (16). The rocket is used as a target. <IMAGE>

Description

SPECIFICATION Rockets This invention relates to rockets and, while being applicable to both guided and unguided rockets, it is particularly applicable to guided rockets. Various situations arise where it is desirable to slow down the flight of the whole or part of a rocket. One example of such a situation is where a guided rocket is being used as a threat simulator in which case the rocket is directed towards a target to simulate a hostile vehicle-and is to be destroyed by a missile launched from the target. Where, in such cases, the missile fails to destroy the rocket, and particularly where the rocket approaches the target at high speed and along a trajectory which is at a steep angle to the horizontal, it is desirable to slow down the rocket in case impact with the target or with vulnerable installations close to the target cannot be avoided.

Our British Patent Specification No. 1 258 044 describes an unguided sounding rocket in which a forward section containing a payload is separated from a rearward section comprising a sustainer motor during upward flight of the rocket, and the rearward section has at its forward end a parachute which is deployed on separation and which renders the rearward section unstable.

While a parachute is satisfactory at the speeds involved near the top of the trajectory of a sounding rocket, it cannot be used at very high speeds.

According to one aspect of the present invention, a rocket includes an inflatable balloon, means for deploying the balloon to a position in which the balloon is connected to but spaced from the body of the rocket, and means for controlling inflation of the balloon.

While the balloon may be arranged to be inflated while the rocket is intact, preferably it is located on a separable rear section containing a motor and non-adjustable guide fins.

According to a second aspect of the invention, a rocket comprises a forward section, a separable rearward section, a drag inducing element attached to the forward end of the rearward section and a timer set to deploy the drag inducing element to a position in which it is connected to but spaced from the body of the rocket a predetermined time after separation of the forward and rear sections. The predetermined time may be selected so that the drag inducing element, which may be a balloon or a parachute, is not deployed until the speed of the rearward section has fallen to a level at which the drag inducing element will not be damaged on deployment, for example to sub-sonic speed.

In some circumstances it may be necessary to actuate the balloon or drag inducing element (and separate the portion carrying the balloon or drag inducing element from the remainder of the rocket where such provision is made) while the rocket motor is still generating propulsive yases. To reduce or eliminate the thrust produced by such generation, the rocket may be provided with a g propulsive gas venting port leading to an exit other than the propulsion nozzle and means for opening the port.

While the balloon may be inflated from gas from a gas generator or from a compressed gas reservoir such as a bottle, provision may be made for inflating it by means of ram air. Thus, the rocket may have an inlet nozzle connected through a controllable valve to the interior of the balloon. The inlet nozzle may face permanently forwards or may be provided with weather cocking means so that it tends to face into the air flow whichever direction this may be in. Although the nozzle may be substantially universal in its mounting it may have only limited weather cocking capability where it is decided that this will provide adequate ram air in the circumstances likely to be encountered.

Where the rocket is separable into a forward section and a rear section, the balloon or drag inducing element is connected to the forward end of the rear section by an articulated linkage which is arranged to hold the balloon or drag inducing element clear ofthe forward end of the rear section and preferably comprises two links of different lengths.

The invention may be carried into practice in various ways but one rocket embodying the invention will now be described by way of example with reference to the accompanying drawings in which Figures 1, 2 and 3 show the complete rocket, the rocket immediately after separation of the forward and rear sections, and the rocket shortly after such separation, respectively.

The rocket consists of a forward section 1 which has adjustable guidance fins 2 and a rearward section 3 which consists of a sustainer rocket motor and has fixed guidance fins 4 at the rear end. The forward section is separable from the rear section on actuation of explosive bolts on receipt of a radio signal.

Housed in the forward section is a balloon housing 6. The balloon is connected to the forward end of the rear section by a pair of jointed links 7 of different lengths.

As can be seen from Figure 3, the balloon housing 6 contains a balloon 8 which is connected to the housing 6 by a harness 9 and which has a neck 11 which is connected to the housing by a flexible tube 12 which leads through the housing 6 to a flexible tube 13 which is coupled to the linkage 7 and leads to a passage 14 within the rear section 3. This passage, which contains a valve 15, leads to an inlet nozzle 1 6 which is mounted for rotation about an axis 1 7 perpendicular to the longitudinal axis of the rocket and is connected to a vane 1 8 which lies on the opposite side of the axis from the nozzle.

At the forward end of the rear section there is a ring of venting ports 20 which are controlled by a sleeve valve 21 and lead to the forward end of the propellant chamber of the motor.

The explosive bolts and the valve 1 5 are under radio control via a receiver 1 9.

In normal flight, the balloon and its housing are contained in the rear of the forward section 1 and the two sections of the rocket are connected by the explosive bolts. If a situation arises in which the flight of the rocket must be modified so quickly that the guidance fins 2 are incapable of producing this modification (for example because a missile fired by the target to which the rocket is directed has failed to destroy the rocket), a signal is sent to the rocket which causes the explosive bolts to separate the forward section from the rear section and causes the sleeve valve 21 to open the vents 20 so that the gases generated in the motor no longer propel the rear section. As separation of the rear section forming the motor from the front section occurs, the housing 6 is withdrawn from the front section as is shown in Figure 2.In this condition, the drag produced by the bluff forward end of the rear section and by the housing 6 will cause the rear section to slow down. On separation occurring, a timer (not shown) is started and after a predetermined time the timer operates a deployment device in the housing 6 which causes the balloon 8 to be ejected. On operation of the deployment device or shortly thereafter, the timer also opens the valve 1 5. The asymmetrical articulated linkage 7 prevents the balloon fouling the forward end of the rear section and holds it clear.Ram air passes through the inlet nozzle and the valve 1 5 and through the flexible tubes 12 and 13 into the interior of the balloon which is progressively inflated and thus causes an asymmetrical drag force to be applied to the rear section which becomes aerodynamically unstable and tumbles and this rapidly decelerates the rear section to a speed at which severe damage to the target is avoided. The rate of opening of the valve and/or the dimensions of the passage joining the inlet nozzle to the interior of the balloon can be so arranged that the balloon is inflated at a controlled rate such that deceleration of the rear section and the loads imposed on the balloon and the remaining parts of the rear section are kept within acceptable levels.

It is possible that the rear section will become aerodynamically unstable and tumble before the deployment device is operated. Alternatively the aerodynamics may be such that the housing 6 will alone prdduce sufficient drag to cause the rear section to reverse its direction of flight and continue relatively stably with the fins 4 first. In this case the balloon when deployed will stream behind the rear section.

In each of the arrangements described, the balloon 8 may be replaced by a parachute which is deployed at a time after separation determined by the timer.

Claims

1. A rocket including an inflatable balloon, means for deploying the balloon to a position in which the balloon is connected to but spaced from the body of the rocket, and means for controlling inflation of the balloon.

2. A rocket as claimed in Claim 1 which comprises a forward section and a separable rearward section, the balloon being attached to the rearward section.

3. A rocket as claimed in Claim 2 in which the rearward section contains a motor and has non-adjustable guide fins.

4. A rocket as claimed in Claim 3 which includes a propulsive gas venting port leading to an exit other than through the propulsion nozzle of the rocket, and means for opening the port.

5. A rocket comprising a forward section, a separable rearward section, a drag inducing element attached to the forward end of the rearward section and a timer set to deploy the drag inducing element to a position in which it is connected to but spaced from the body of the rocket a predetermined time after separation of the forward and rear sections.

6. A rocket as claimed in Claim 5 in which the rearward section contains a motor and has non-adjustable guide fins.

7. A rocket as claimed in Claim 6 which includes a propulsive gas venting port leading to an exit other than through the propulsion nozzle of the rocket and means for opening the port.

8. A rocket as claimed in Claim 5 or Claim 6 or Claim 7 in which the drag inducing element is a parachute.

9. A rocket as claimed in Claim 5 or Claim 6 or Claim 7 in which the drag inducing element is a balloon.

10. A rocket as claimed in any of Claim 1 to 4 or in Claim 9 which includes a gas generator or a compressed gas reservoir for inflation of the balloon.

11. A rocket as claimed in any of Ciaims 1 to 4 or in Claim 9 which includes a ram inlet nozzle connected through a controllable valve to the interior of the balloon.

12. A rocket as claimed in Claim 11 in which the inlet nozzle is provided with weather-cocking means.

1 3. A rocket as claimed in any of the preceding claims in which the balloon or drag inducing element is connected to the forward end of the rearward section by an articulated linkage which is arranged to hold the balloon or drag inducing element clear of the forward end of the rearward section.

14. A rocket as claimed in Claim 13 in which the articulated linkage comprises two links of different lengths.

1 5. A rocket substantiaily as described herein with reference to the accompanying drawings.