TOW CABLE

Abstract

A tow cable for a decoy on a fast jet aircraft is described. The tow cable has a composite structure with a high friction fibre outer containment braiding, and low friction fibre internal strength members. Additional to these internal fibres may be electrical conductors and optical fibres. The whole composite providing a tow cable with high towing endurance and reliable in-flight performance, for flight profiles including high performance manoeuvres and in-flight refuelling.

Claims

1. A towed decoy cable for deployment from an aircraft, the tow cable comprising: a core having a relatively low fibre frictional coefficient as compared with a relatively high fibre frictional coefficient outer sheath surrounding the core, the high friction outer sheath being configured for a deployment mechanism for controlling deployment of the decoy from the aircraft.

2. A tow cable according to claim 1, in which the core comprises: a series of interwoven fibres.

3. A tow cable according to claim 1, in which the outer sheath comprises: a braiding of the relatively higher fibre frictional coefficient material.

4. A tow cable according to claim 1, in which the core comprises: electrical conductors and optical fibre cables.

5. A tow cable according to claim 1, in which the core strength fibre material is a thermotropic LCP.

6. A tow cable according to claim 1, in which the outer braid material is a lyotropic LCP.

7. (canceled)

8. A tow cable according to claim 5, in which the thermotropic LCP is Vectran.

9. A tow cable according to claim 6, in which the lyotropic LCP is Kevlar.

Description

[0007] The invention will now be described with reference to the following drawings in which:

[0008] FIG. 1 is a schematic drawing of a decoy and tow cable deployed behind an aircraft in accordance with one form of the invention. The tow point is located sufficiently away from the engines and flight control surfaces, such that only aerodynamic forces are impressed upon the tow cable structure and decoy. The diagram is necessarily not to scale but indicates the general arrangement.

[0009] FIG. 2 is a schematic drawing of a cross section of the tow cable of FIG. 1 in accordance with one form of the invention.

[0010] FIG. 2 shows one form of tow cable in accordance with the invention. The tow cable comprises a series of internal fibre bundles produced from low frictional fibres, surrounded by (and contained by) an external braid produced from a high frictional fibre material. The tow cable may further include integral electrical and optical fibre conductors as required for the operation of the decoy. Manmade fibres using liquid crystal polymer technology can provide fibres with the necessary high and low friction properties. Lyotropic LCPs, such as Kevlar, can provide the high friction fibres, whilst thermotropic LCPs such as Vectran, can provide the low friction fibres.

[0011] In this way, the tow cable can withstand the extreme inter-fibre dynamics as well as the tensile loads needed for towing a high drag body such as a towed decoy. The critical characteristic is low inter-fibre friction that minimises cable self-fretting which is the cause of cable failure under these conditions. Such low friction characteristics minimise fibre-on-fibre damage and hence prolong cable life.

[0012] A tow cable with this structure can typically provide hours of towing capability, with complex flight profiles comprising high ‘g’ manoeuvres, high aircraft speed excursions such as 350 knots to supersonic speeds, and low drag conditions as experienced during in-flight refuelling.

[0013] This invention has identified a tow cable composite structure and fibre chemistry which enables a high endurance tow cable for use in a severe vortex aero environment. It will be appreciated that whilst that whilst the specific examples of Kevlar and Vectran fibres are given above, any suitable combination of materials having the desired properties may be used.