GB2385310A

GB2385310A - Satellite launch assembly including means for connection and release

Info

Publication number: GB2385310A
Application number: GB0203513A
Authority: GB
Inventors: Graham Michael Flawn
Original assignee: Insys Ltd
Current assignee: Insys Ltd
Priority date: 2002-02-14
Filing date: 2002-02-14
Publication date: 2003-08-20
Also published as: GB0203513D0

Abstract

A satellite launch assembly including means to support and restrain the satellite on a launch platform prior to launch (13,14,15 fig 3), and means to push and rotate the satellite to effect launch and in so doing impart spin and momentum. The pushing means being rotated. The pushing means may include a piston travelling in a cylinder having a surface in contact with a pusher plate (25 fig 8) which has slots (26 fig 9) engaging with drive dogs (27 fig 9) on an annular attachment ring 2 located centrally on the satellite base to impart rotation from the piston, the piston may be actuated by a compressible member (24 fig 10) such as a spring. The means for rotation of the piston means may include a pin and helical track. The restraint means (14 fig 3) may include a detent released by an actuator 7 which may be pyrotechnic. The detent may include a rotatable ring 6 which rotates between a locked and unlocked position. A releasable electric plug and bracket 8 may also be included.

Description

Satellite Ejection Mechanism This invention relates to a mechanism for deploying satellites or probes from a main satellite or other launching platform.

Satellites are carried into space on launching satellites or rockets, referred to herein as the"launching platform". In a zero gravity environment any motion imparted to the satellite as it is deployed continues as it travels in space. For example if the ejection mechanism imparts a tilt, the satellite will move off into space rotating in the direction of the tilt.

A common way of deploying satellites is to release them from the launching base by detonating a plurality (usually three) of explosive bolts, thus releasing the restraint and imparting thrust in the desired direction. It is difficult, if not impossible, to achieve exactly synchronized and even detonation and explosion, and as a consequence these systems impart the above described unwanted rotation, known as"tip off".

The present invention is directed towards eliminating tip off.

The invention is now described by way of example with reference to the accompanying drawings in which :- Figure 1 illustrates an embodiment of the invention shown in perspective from below in a stowed configuration for launch ; Figure 2 is a partial cross section of the assembly and configuration of Figure 1; Figure 3 is a partial cross section through bolts after release for the cruise phase; Figure 4 is a plan view from below showing the clamped configuration ; Figure 5 is a plan view similar to Figure 4 after activation of the unclamping mechanism;

Figure 6 is a cross section showing detail of the restraint mechanism ; Figure 7 shows the restraint mechanism of Figure 6 at a later stage in release; Figures 8 to 10 show later stages in ejection ; and Figures 10 and 11 show an alternative embodiment for releasing the locking assembly.

Figure 1 shows from below the attachment of a probe assembly to an ejection mechanism in a configuration suitable for take off. The drawing shows the aft cover 1 of the probe which has a downwardly extending grooved attachment ring 2 that fits over the ejection mechanism 5 and to which it is locked by a locking arrangement described later.

During platform launch the probe is provided with additional clamping for transference of load to the platform. Any suitable clamping may be used as this is not part of the probe eject mechanism. In Figure 1 the additional clamping to the probe is via three frangible bolts 3 which are secured to the platform by bolted brackets 4, which extend from a base plate 21 on the ejection mechanism 5.

Also seen in Figure 1 as parts of the locking arrangement of the ejection mechanism are a rotation ring 6 in a recess in the base plate 21 and two pyrotechnic actuators 7 attached between the base plate and the rotation ring 6. There is also an electrical plug and plug bracket assembly 8 attached between the mounting of one of the actuators 7 and the probe cover 1. Centrally of the base plate 21 there is a housing 9 for an ejection spring (shown in later figures). A further flight pin 10 can also be seen.

Referring now to Figures 2 and 3 a vertical cross section shows further detail of the locking arrangement 12 that retains the probe in position during flight of the launch platform to the ejection destination At this stage, after launch, the bolts 3, will have disconnected, as can be seen in Figure 3 where a line of weakness 11 fractures to provide the disconnection.

The locking arrangement may be any suitable form but in the embodiment shown it comprises ball bearing detents, of which several, say eight, may be provided between the

periphery of the rotation ring 6 and the attachment ring 2 where the probe attaches to the ejection mechanism. As can be seen, the lower part of the attachment ring 2 carries a grooved collar 13 that engages with ball bearing 14, which is in turn held in place by a clamping surface 15 that is part of the rotation ring assembly 6.

Referring now to Figures 4 and 5, these show plan views from below before and after firing of the actuators 7 which initiates rotation of the rotation ring 6. In Figure 4, the rotation ring 6 is shown in an unrotated position with the plug 16 of the plug and plug support bracket assembly 8 engaged in a socket carried by a bracket 19 on the probe.

When the actuators are fired the rotation ring rotates (clockwise as shown) to the position shown in Figure 5. It will be seen that the plug, carried by the support bracket and clamping ring has separated from the socket and the extended actuator arm 20 can be seen pushing against the engaging part of the clamp ring. The body of the actuator remains static attached to the base plate 21 of the ejection mechanism.

Figures 6 and 7 illustrate in cross section the release of the ball bearing detent that takes place once the actuators have fired and rotated the rotation ring 6. On the rotation ring 6 spaced from the clamp surfaces 15 there are holes 22 that are brought into register with the balls 14, instead of clamp surface 15, when the clamp ring rotates (Compare with Figure 3 where the clamp surface 15 holds the balls in position). When the ejection mechanism commences operation (as described later) and the probe begins to lift, the lower surface below the groove 13 of attachment ring 2 now is able to push the balls into their registering holes to release the detent, leaving the probe free to be separated. It will be noted that there is a small retaining lip 23 on the ball housing that prevents the ball from falling out Figures 8,9 and 10 illustrate the operation of the ejection mechanism which provides momentum from a single location and also imparts a stabilizing spin. A spring 24 is retained within housing 9 and until the ball detents are released it is held in a compressed state bearing against a pusher plate 25 which also engages with and pushes against the attachment ring 2 Referring to Figure 8, it will be seen that the outer rim of pusher plate 25 engages with a shoulder on the attachment ring 2 just above the groove 13. When the actuators fire and rotate the locking ring to bring the holes into alignment with the balls,

the upward pushing of the spring is no longer held by the ball detent as there is now no resistance to the balls being pushed inward by the shoulder of groove 13 as the pushing plate rises, also raising the probe and attachment ring. The expansion of the spring provides the ejection force for the probe which continues in the same direction of motion separating from the pusher plate, once the expansion of the spring is completed. It will be appreciated that this provides a single release point at the time of probe separation, unlike previous systems where separation is at the time of multiple releases from spaced apart points.

Further stability to the probe can be provided by spinning it around the axis of its direction of travel, i. e. around the ejection direction. This may be achieved by having a helically grooved piston attached to the pusher plate with guide bolts extending from an outer part of the housing 9. The piston is rotatable within the housing 9 so that as the spring expands the helical grooves of the piston run over the guide bolts imparting rotation to the piston and the pusher plate. The outer periphery of the pusher plate, where it comes into engagement with the attachment ring is provided with slots 26 that engage with drive dogs 27 on the inside of the attachment ring, thereby transferring the spin to the probe.

Alternative mechanisms to a spring may be used for moving the piston and pushing plate, for example hydraulic or pneumatic systems, or compressible solid materials.

It will be appreciated that alternative detent and detent release mechanisms may be provided, although it is generally convenient to utilise a ring arrangement in order to achieve synchronized movement and release.

In Figures 11 and 12 an alternative rotation mechanism for unlocking the detent mechanism is shown. Referring to Figure 11 the base plate 21 has a grooved outer track 30 with spaced apart raised blocks 31. Each block 31 has a cut out for receipt of one end of a compressible member such as a helical spring 32 (Figure 12). A rotatable ring member comprising a generally flat ring base with raised, recessed blocks similar to blocks 3 1 engages in the groove 30 with the spaced apart raised blocks 31. Figure 12 shows the arrangement from above with spring 32 extending between one of the base

plate blocks 31 and one of the rotating ring blocks 34. A spring 32 will be provided between each pair of blocks 31 and 34 It will be appreciated that the blocks 34 do not occupy the entire space 33 in the groove of the base plate, and therefore the upper ring is rotatable with corresponding compression or expansion of the springs 32. In operation, the springs are compressed and the rotatable ring locked by a releasable means. In this configuration the springs provide a stored energy device. When the releasable means is released, the springs expand, rotating the rotatable ring and releasing the ball detents as described for the previous embodiment.

The actuation force provided by the stored energy device can be adjusted to suit the loading requirements, for example by selection of the size, stiffness and number of springs or by using an alternative compressible medium which may be gas, hydraulic or solid. Compressible plastics or rubbers may be particularly suitable, or may be used in composite devices. It will be appreciated that anchor points other than recesses may be provided.

Claims

1. An assembly for deploying a probe from a launching platform, the assembly comprising a pushing member with a surface for supporting the probe, a restraint that holds the surface and probe in contact, means for releasing the restraint leaving the surface and probe in contact, means for moving the pushing member through a travel distance to impart momentum to the probe, and means for rotating the pushing member about the axis of the travel distance so as to impart spin to the probe.

2. An assembly according to claim 1 in which the pushing member has means for rotational engagement with the probe

3 An assembly according to claim 1 or claim 2 in which the surface of the pushing member engages with an annulus disposed centrally on the base of the probe

4 An assembly according to claim 2 and claim 3 in which the means for rotational engagement comprises a log an recess on the surface and annulus.

5 An assembly according to claim 1 in which the pushing member comprises a piston that travels in a piston cylinder and the pushing force for the cylinder comprises a compressible member

6 An assembly according to claim 5 in which the means for rotating the pushing member comprises a pin and helical track disposed on respective ones of the piston and piston cylinder

7. An assembly according to any preceding claim in which the restraint comprises a detent released by an actuating member.

8. An assembly according to claim 8 in which the detent comprises a ring rotatable between a locking position and an unlocked position.

9. An assembly according to claim 7 or claim 8 in which the actuating member comprises a rod actuator.

10. An assembly according to claim 7 or claim 8 in which the actuating member comprises a compressible element.

11. An assembly substantially as hereinbefore described with reference to and as illustrated in any of the accompanying drawings.