Composite Tow Cable for Decoy Deployment
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Solution Overview
Problem
Existing tow cables for towed decoys deployed from high-performance aircraft suffer from early detachment due to high inter-fibre friction, leading to fretting failure and unpredictable performance during high 'g' manoeuvres and severe vortex environments.
Innovation Solution
A tow cable design featuring internal fibre bundles made from low friction materials, such as thermotropic liquid crystal polymers like Vectran, surrounded by an external braid of high friction fibres like Kevlar, which minimizes inter-fibre friction and prevents self-fretting, thereby enhancing cable durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high friction fibres such as Kevlar are used for the tow cable, then the cable provides high strength to weight ratio, but the high inter-fibre friction causes self-fretting and fibre fracture leading to early cable failure
Solution Approach 1:
The patent employs a composite cable structure combining two different fibre types: high friction fibres (Kevlar) for strength and low friction fibres (Vectran) for reduced self-fretting. The inner core uses Vectran to minimize fibre-on-fibre damage during relative movement, while the outer braid uses Kevlar to provide the necessary tensile strength and structural integrity for towing decoys from high-performance aircraft.
2Stability of the object's composition
If the decoy is designed to be highly stable with centre of mass following the cable, then aerodynamic stability is improved, but in high vortex environments the decoy axis deviates up to 90 degrees causing significant cable fibre relative movement
Solution Approach 1:
The low friction Vectran fibres act as an intermediary between the high friction Kevlar outer braid and the internal cable structure. This intermediary material allows for necessary fibre movement and deformation in high vortex environments without causing self-fretting damage, accommodating the decoy's angular deviations while protecting the load-bearing Kevlar fibres.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cable achieves extended towing capability, capable of withstanding high 'g' forces and supersonic speeds, with reduced fibre damage and prolonged life, ensuring reliable decoy deployment and multiple decoy carriage.
Implementation Method 1
the low friction internal fibres of the cable provide the high endurance strength members necessary for successful operation of the cable
Implementation Method 2
thermotropic LCPs such as Vectran (RTM), can provide the low friction fibres
Implementation Method 3
Lyotropic LCPs, such as Kevlar(RTM), can provide the high friction fibres
Data Source
Figure 1~2
AI summary
A tow cable for a decoy on a fast jet aircraft is described. The tow cable has a composite structure consisting of 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.