GB2249820A

GB2249820A - Fibre guided missile

Info

Publication number: GB2249820A
Application number: GB9025057A
Authority: GB
Inventors: John Anstiss Churchill
Original assignee: STC PLC
Current assignee: STC PLC
Priority date: 1990-11-17
Filing date: 1990-11-17
Publication date: 1992-05-20
Anticipated expiration: 2010-11-17
Also published as: GB9025057D0; GB2249820B

Abstract

A fibre payout arrangement for an optical fibre guided missile includes means for preventing premature deployment of the fibre in the initial stages of flight. Fibre 12 payed out from a storage bobbin 11 engages flexible means, e.g. an annular array of abradable bristles 16. These dissipate energy from the fibre without causing damage, but are worn away after the initial part of the trajectory. <IMAGE>

Description

FIBRE GUIDED MISSILE This invention relates to optical fibre controlled guided missiles, and in particular to a fibre payout arrangement for such missiles.

Guided missiles have been developed in which directional control of the missile is effected via a fibre optic link between the missile and the launch station. Conventionally the optical fibre is stowed within the missile in the form of a coil from which the fibre is payed out during the flight from the launch station to the target. During the flight, directional control signals are relayed from the launch station to the missile via the optical fibre.

A significant problem with this arrangement is the premature deployment of the fibre from the dispenser coil in the initial stages of the flight. During the acceleration phase following launch of the missile, the fibre may be pulled prematurely from the dispenser coil by efflux drag on the fibre. Conventional techniques for controlling the dispensing of filamentary. materials from a coil are not adaptable to one with the very high payout speeds inherent in this particular application.

It will be appreciated that, at the very high payout speeds achieved during missile flight, there is considerable risk of damage to the fibre. Even when the fibre is undamaged, it has been found that conventional retardation devices introduce excessive strain in the fibre thus impairing its light transmissive properties.

The object of the invention is to minimise or to overcome this disadvantage.

According to the invention there is provided an optical fibre payout arrangement for a fibre controlled vehicle, including means for storing an optical fibre in the form of a coil from which, in use, the fibre may be payed out, and flexible means engaging the payed out fibre so as to provide braking of the fibre at least during the initial stages of payout of the fibre whereby to inhibit premature deployment of the fibre from the coil.

According to the invention there is further provided an optical fibre payout arrangement for a fibre controlled missile, including a generally cylindrical bobbin on which an optical fibre is stored in the form of a coil and from which, in use, the fibre may be payed out in a generally axial direction, and fibre retardation means including an annular array of inwardly directed flexible members engaging the fibre payed out from the coil so as to provide braking of the fibre at least during the initial stages of payout of the fibre whereby to inhibit premature deployment from the coil.

An embodiment of the invention will now be described with reference to the accompanying drawing in which the single figure is a cross-sectional view of an optical fibre dispensing or payout arrangement e.g. for a fibre controlled guided missile.

Referring to the drawing, the payout arrangement includes a generally cylindrical bobbin-ll on which an optical fibre 12 is stored in the form of a coil 13 wound on to the bobbin. Typically the fibre 12 is a so-called disperser fibre which has only a thin surface coating so as to allow a long length of fibre to be accommodated on the bobbin.

The bobbin 11 is enclosed in a protective generally cylindrical housing 14 spaced from the bobbin 11 so as to define an annular air space 15 therebetween. The stored optical fibre coil 13 is accommodated in this air space.

In use, the fibre 12 is payed out from the coil 13 via the annular air space 15 between the bobbin and the housing. It will be appreciated that as the fibre 12 is drawn from the coil, it sweeps around the surface of the bobbin 11, there being one sweep for each turn of the coil.

During payout, the fibre is braked to prevent premature deployment from the coil. This braking is achieved by energy dissipation from the payed out fibre. The inner surface of the housing 14 is provided with an annular array of inwardly directed flexible members, e.g. bristles 16, obstructing the annual air space 15.

As the fibre 12 sweeps around the bobbin surface during payout its path is partially obstructed by the bristles. The movement of the fibre displaces the bristles 16 thus causing dissipation of energy from the moving fibre. Advantageously the bristles are formed from a readily abradable material, such as a polyolefin or a polyamide, so that they are worn away by contact with the fibre after the initial part of the missile trajectory. We have found that braking of the fibre to inhibit premature deployment is required only for the first few seconds of flight.

In some applications the bristles 16 may be replaced by flexible strip members or by a flexible plastics annular membrane.

The degree of braking exerted on the fibre 12 by the bristles 16 is determined by the resilience of the bristles and on their mechanical hysteresis properties. It will thus be appreciated that the dimensions and the material composition of the bristles may be selected to provide the desired degree of energy dissipation for a particular application.

We have found that the arrangement described above provides smooth braking of the fibre and overcomes the problem of premature deployment without the risk of fibre damage.

The arrangement described above is of particular application to fibre optic guided missiles having centre or side venting motors. It is however applicable to other guided vehicles such as radar decoy targets.

Claims

1. An optical fibre payout arrangement for a fibre controlled vehicle, including means for storing an optical fibre in the form of a coil from which, in use, the fibre may be payed out, and flexible means engaging the payed out fibre so as to provide braking of the fibre at least during the initial stages of payout of the fibre whereby to inhibit premature deployment of the fibre from the coil.

2. An optical fibre payout arrangement for a fibre controlled missile, including a generally cylindrical bobbin on which an optical fibre is stored in the form of a coil and from which, in use, the fibre may be payed out in a generally axial direction, and fibre retardation means including an annular array of inwardly directed flexible members engaging the fibre payed out from the coil so as to provide braking of the fibre at least during the initial stages of payout of the fibre whereby to inhibit premature deployment from the coil.

3. An optical fibre payout arrangement as claimed in claim 2, wherein said flexible members comprise an array of plastics bristles.

4. An optical fibre payout arrangement as claimed in claim 2 or 3, wherein said flexible members comprise a polyolefin or a polyamide.

5. An optical fibre payout arrangement as claimed in claim 2, 3 or 4, wherein the flexible members are formed from readily abradable material whereby to provide braking only during the initial stages of payout of the fibre.

6. An optical fibre payout arrangement substantially as described herein with reference to and as shown in the accompanying drawings.

7. An optical fibre controlled missile provided with a fibre payout arrangement as claimed in any one of the preceding claims.