Pyrotechnic Cutting Cord with Segmented Casing for Aeronautics

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Solution Overview

Problem

Conventional pyrotechnic cutting cords have suboptimal cutting performance and reproducibility due to deformation of the explosive core relative to the coating, use toxic lead, and generate harmful rear effects, making them unsuitable for aeronautical and space applications.

Innovation Solution

A pyrotechnic cutting cord with a casing comprising two distinct parts, a thin rear part and a thicker front part with lateral wings, where the explosive material is applied to the middle zone, and the casing is made of non-toxic materials like aluminum or composite plastics, minimizing rear effects and enhancing cutting reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a lead sheath is used to contain the explosive material, then the cutting cord can be manufactured with a simple single-part structure, but the cutting performance is not optimized and reproducibility is poor due to deformation of the explosive core relative to the coating

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcutting performance reproducibility
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The casing is divided into two distinct parts: a rear part and a front part. The front part is specifically designed with a thicker wall structure to properly contain the explosive material and maintain its shape, while the rear part provides structural support. This segmentation allows each part to be optimized for its specific function, ensuring proper explosive core positioning and coating alignment for consistent cutting performance.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If lead is used as the casing material, then the cord can be manufactured with a single material type, but lead is toxic and must be limited, especially for aeronautical and space applications

Engineering Contradiction:
Improvematerial uniformityVSAvoidtoxicity
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention employs composite materials for the casing, specifically using non-toxic materials such as plastics or composite materials instead of lead. The front part and rear part can be made from different materials optimized for their specific functions, eliminating the toxicity issue while maintaining structural integrity and manufacturing feasibility.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If a single-part casing structure is used, then the manufacturing process is simpler, but rear effects (projection of shards) are particularly harmful in aeronautical applications

Engineering Contradiction:
Improvestructural simplicityVSAvoidrear effects
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

By dividing the casing into a front part and a rear part with different structural characteristics, the design allows the front part to be optimized for containing the explosive material with appropriate thickness to minimize shard projection, while the rear part provides structural support. This segmentation effectively reduces harmful rear effects without overly complicating the manufacturing process.

Inventive Principle:
Principle #1Segmentation

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 solution provides a reliable, cost-effective, and space-efficient cutting cord with improved cutting performance and reduced rear effects, addressing the limitations of conventional cords by optimizing the geometry and material selection.

Implementation Method 1

The initiation of the explosive causes the projection of the coating at high speed according to the classic principle of operation of the shaped charges

Methodology Applied
Scientific EffectShaped charge: Shaped Charge

Implementation Method 2

The initiation of the explosive causes the projection of the coating at high speed

Methodology Applied
Scientific EffectDetonation: Detonation

Data Source

PatentEP2075525B1Pyrotechnical cutter fuse and method of manufacturing such a fuse
Publication Date: 2011.09.07 NEXTER MUNITIONS SA
  • EP2075525B1 patent drawingFigure 1~2
  • EP2075525B1 patent drawingFigure 3
  • EP2075525B1 patent drawingFigure 4~5

AI summary

The pyrotechnic cutting cord (1) useful in military aircrafts and launchers, comprises an explosive material (5) disposed in a casing (2), and a metallic profile that forms a coating of the cut and is applied against the explosive material. The casing comprises two distinct parts assembled one after the other. The two distinct parts include a thin rear part or a covering (2a), and a thick front part (2b). The front part comprises two lateral wings (3a, 3b) forming a support for the covering and connected by a median zone that forms the coating of the cut. The pyrotechnic cutting cord (1) useful in military aircrafts and launchers, comprises an explosive material (5) disposed in a casing (2), and a metallic profile that forms a coating of the cut and is applied against the explosive material. The casing comprises two distinct parts assembled one after the other. The two distinct parts include a thin rear part or a covering (2a), and a thick front part (2b). The front part comprises two lateral wings (3a, 3b) forming a support for the covering and connected by a median zone that forms the coating of the cut, and is constituted by the metallic profile. The covering has a constant thickness, and is made of plastic or a composite material. The explosive material is applied in the form of a narrow sheet on the median zone of the front part. The narrow sheet is maintained in a place by the covering. An independent claim is included for a process for the fabrication of a cutting cord.