GB2218058A - Launching system for acceleration-sensitive body - Google Patents

Abstract

A launching system for a body, e.g. a remotely piloted vehicle (10) includes means for launching a ballistic projectile (13) to the body (10). Energy-absorbing means are provided to absorb energy imparted by the projectile so as to keep the acceleration of the body below the acceptable limit. The absorbed energy may be transferred to the body if an elastic line is used as the connecting means, or may be dissipated as heat by a retarder (Figs 2-5). <IMAGE>

Description

LAUNCHING SYSTEM FOR ACCELERATION-SENSITIVE BODY Various types of body require to be launched into flight including gliders and remotely-piloted aircraft such as target drones. Launching is frequently effected by some form of catapult or by means of rockets. In most cases the launched body has to be treated with some care as it may include items of equipment which can be damaged by excessive acceleration.

However the launching methods so far described do not normally produce excessive acceleration forces.

Rocket-assisted launching systems are relatively expensive to use, whilst catapult systems are usually bulky and mechanically complex.

It is an object of the invention to provide a simple and inexpensive launching system for an acceleration-sensitive body.

According to the present invention there is provided a launching system for an acceleration-sensitive body, which includes means for launching a ballistic projectile and connecting means connecting the body to the ballistic projectile and including energy-absorbing means arranged to absorb energy imparted by the projectile such that the acceleration limits of the body are not exceeded.

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram showing a first embodiment of the invention; Figure 2 is a schematic diagram showing a second embodiment of the invention; Figure 3 illustrates a feature of the embodiment of Figure 2; Figure 4 illustrates an alternative feature of the embodiment of Figure 2, and Figure 5 is a schematic diagram showing a third embodiment of the invention.

Referring now to Figure 1 this shows, in purely schematic form, an acceleration-sensitive body 10 such as a remotely-piloted vehicle or RPV. The RPV is mounted on a launching ramp 11. Mounted adjacent to the launching ramp 11 with it barrel 12 aligned substantially parallel with the ramp is a launcher for a ballistic projectile 13. The launcher may conveniently be a short-barrelled gas gun. The ballistic projectile 13 is connected to the RPV 11 by an elastic rope or cable 14, a quantity of which is flaked in a container 15, that is stowed in the container 15 so that it will pay out evenly without snagging.

In operation the ballistic projectile 13 is fired from the gas gun 12 the elastic line 14 is payed out from the container 15. When the line is fully payed out it becomes stretched by the continued movement of the projectile, thus storing energy in the line.

When the energy stored in the line 14 either overcomes friction between the RPV 11 and the ramp 11, or causes the release of a latch holding the RPV to the ramp, then the RPV moves away from the ramp and accelerator gradually as the energy stored in the line 14 is converted into kinetic energy imparted to the RPV.

Eventually the ballistic projectile 13 will decelerate and its velocity will be exceeded by that of the RPV 10. At this time the tension in the line 14 will fall to zero. The line must then be disconnected from the RPV 10 to allow the RPV to continue to fly under its own power. To achieve this the line 14 must be attached to the RPV by a latch which is initially actuated when tension in the line increases as the ballistic projectile is launched and which disengages the line when the tension falls to zero.

The elasticity of the rope 14 will ensure that the acceleration of the RPV is gradual. By suitable choice of elasticity the acceleration may be kept within the limits which the launched body will withstand.

Clearly it is essential to ensure that the RPV 10 cannot collide with the ballistic projectile 13 after launch.

An RPV will be controllable in flight and will have lift imparted by its wings and hence its path should be different from that of the projectile 13. If the launched body 10 is not an RPV then steps may have to be taken to modify the trajectory of the projectile 13 so that it remains below that of the launched body.

The embodiment above has the advantage of being basically very simple. However, various alternative arrangements are possible and these will now be described.

Figure 2 is a diagram showing one possible alternative. In place of the elastic line of Figure 1 stowed in a container between the ballistic projectile 13 and the launched body 11, Figure 2 shows a line 20 extending between the projectile 13 and the body 10 and passing through a retarder 21 and a guide 22 attached to the body 10. The main quantity of the line is flaked in a container 23 located behind the ramp 11. The short section of line between the projectile 13 and the body 10 may contain a shock-absorbing or elastic section (not shown).

When the body 10 is to be launched the ballistic projectile 13 is fired from the gas gun 12 as before. Very soon after the projectile has been fired the line between projectile and body will become taut and the body 10 will be launched. The line 20 runs through the retarder 21 so that some of the energy of the projectile is transferred to the body 10 and the remainder is dissipated by the retarder. Suitable adjustment of the retarder ensures that the acceleration of the body 11 remains with the necessary limits.

Eventually the entire length of line will be pulled through the retarder 21 and the line will be pulled clear of the body.

The retarder 21 could take several forms. Figure 3 shows a simple friction block arrangement having three or more fixed blocks 30 between which the line 20 passes. The positions of the blocks 30 relative to the diameter of the line 20 determine the friction force exerted on the line as it passes through the retarder.

Figure 4 shows an alternative form of retarder. In this case the line 20 passes between a pair of rollers 40 which rotate at a rate determined by a suitable braking arrangement.

In yet another form the retarder may take the form of a die through which the line passes and which acts to change the cross-sectional profile of the line.

In either form of retarder the excess energy is dissipated as heat.

Figure 5 illustrates a third embodiment of the invention. In this, which is basically very similar to the embodiment of Figure 2, the line 20 is replaced by a hollow flexible tube 50 filled with a fluid. The end of the tube attached to the projectile 13 or to a short shock-absorbing section of line 51 is sealed and a pressure-relief valve 52 is fitted to the remote end of the tube. The retarder of Figure 2 is replaced by a pair of rollers 53 which restrict the internal cross-section of the tube. The main length of the connecting tube 50 is flaked in a container 54 located behind the body 10.

When the body 10 is to be launched the projectile 13 is fired from the gas gun 12 as in previous embodiments. Soon after the projectile is fired the line between it and the body 10 will become taut, with initial shock being absorbed by the section of line 51. The tube 50 runs through the rollers 53 carried by the body 10. The rollers compress the tube and cause a build-up of pressure inside the tube, thus limiting the speed at which the tube will feed through the rollers. The pressure-relief valve 52 determines the internal fluid pressure. Excess fluid escapes from the tube through the relief valve as the tube passes through the pair of rollers 53. Thus some of the energy imparted to the tube by the projectile 13 is transferred to the body 10 through the rollers 53 whilst the excess energy is dissipated in compressing the fluid contained in the tube. Eventually the entire length of tube will pass through the rollers and the tube will be pulled clear of the body 10.

Other means of restricting the tube may be used in place of the pair of rollers referred to above. The rollers may have grooves to define the cross-section of the tube.

Claims (10)

Claims:

1. A launching system for an acceleration-sensitive body, which includes means for launching a ballistic projectile and connecting means connecting the body to the ballistic projectile and including energy-absorbing means arranged to absorb energy imparted by the projectile such that the acceleration limits of the body are not exceeded.

2. A system as claimed in Claim 1 in which the connecting means includes an elongated elastic member such that energy absorbed by the member is transferred to the body.

3. A system as claimed in Claim 1 in which the connecting means includes an elongated substantially non-extensible member and in which the energy-absorbing means comprise retarding means attached to the body through which the member passes and operable to impede movement of the member relative to the body such that part at least of the energy imparted by the projectile is dissipated, the major part of the length of the connecting means being stowed, prior to the launch of the projectile, behind the body.

4. A system as claimed in Claim 3 in which the connecting means comprises a line.

5. A system as claimed in Claim 4 in which the line may include a short energy absorbing section connected to the projectile.

6. A system as claimed in either of Claims 4 or 5 in which the retarding means comprise at least three fixed blocks arranged to exert a frictional retarding force on the line.

7. A system as claimed in either of Claims 4 or 5 in which the retarding means comprise a pair of rollers between which the line passes and includes means for controlling the rate of rotation of the rollers.

8. A system as claimed in Claim 1 in which the connecting means includes a fluid-filled flexible tube having a pressure-relief valve located in the end remote from the projectile and in which the energy-absorbing texans comprise restricting means attached to the body for restricting the internal cross-section of the tube as it passes through the means such that part at least of the energy imparted by the projectile is dissipated in pressurising said fluid, the major length of the tube being stowed, prior to the launch of the projectile, behind the body.

9. A system as claimed in Claim 8 in which the restricting means comprise a pair of rollers.

10. A launching system for an acceleration-sensitive body substantially as herein described with reference to the accompanying drawings.