Projectile Fin Deployment Mechanism Without Protective Cap

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Solution Overview

Problem

Existing fin deployment mechanisms for projectiles pose a risk of injury and damage due to the cap used for protecting the fins, which becomes a projectile and causes unintended harm upon deployment, and they often have complex designs with multiple components.

Innovation Solution

A fin deployment mechanism that uses a base unit with gas-generating ducts to deploy fins after the projectile leaves the barrel, eliminating the need for a protective cap by using chemical binding agents, combustible rings, and shear studs to securely attach and deploy the fins, ensuring a capless and simpler design with fewer components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a protective cap is used to protect the fins during launch, then the fins are protected from damage, but the cap becomes a projectile and causes injury and damage upon deployment

Engineering Contradiction:
Improvefin protectionVSAvoidinjury and damage from cap
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention removes the protective cap entirely from the system. Instead of having a cap that needs to be deployed and removed, the fins are designed to be exposed from the beginning, eliminating the source of harm while maintaining fin protection through alternative means such as streamlined shaping or protective coatings that do not become projectiles.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention converts the potential harm of the cap into a benefit by using the same structural concept to create a protective fairing that integrates with the fin assembly. The fairing protects the fins during launch but is designed to disintegrate harmlessly or be jettisoned in a controlled manner that does not create projectile hazards.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Strength

If a protective cap is used to protect the fins, then the fins are protected, but the design becomes more complex with multiple components

Engineering Contradiction:
Improvefin protectionVSAvoidnumber of components
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

By removing the protective cap entirely, the invention reduces the number of components from multiple parts (cap, fin assembly, mounting mechanisms, deployment mechanisms) to a simpler integrated fin assembly. This extraction of the unnecessary protective element directly reduces device complexity while maintaining essential protection functions.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the protective function directly into the fin assembly structure itself, rather than having a separate protective cap. The fins are integrated with the body tube in a streamlined configuration that provides protection through aerodynamic design rather than through additional mechanical components.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If chemical binding agents are used to attach fins to the base unit, then the fins are securely attached, but the deployment mechanism becomes more complex

Engineering Contradiction:
Improvefin attachmentVSAvoiddeployment mechanism complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The invention replaces complex mechanical attachment and deployment mechanisms with chemical binding agents. The fins are attached using adhesives or chemical bonds that provide secure attachment during launch, and deployment is achieved through controlled release of these chemical bonds rather than through mechanical actuators, reducing overall system complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention uses changes in chemical parameters (such as temperature, pressure, or chemical reaction activation) to control the bonding strength of the attachment agents. The chemical bonds remain strong during launch but can be selectively weakened or broken through parameter changes to enable fin deployment, providing a simple yet effective deployment mechanism.

Inventive Principle:
Principle #35Parameter changes

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

This solution reduces the risk of injury and damage by eliminating the cap and simplifies the design, while ensuring reliable and efficient fin deployment, enhancing safety and reducing the complexity of the projectile's components.

Implementation Method 1

at least one gas duct is arranged in the base unit so as to conduct pressurized gas generated by the gas-generating device to the bottom side of the fins bearing in the retracted position against the base unit, in order to create a force which acts on the fins for deployment of the same

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Implementation Method 2

the fins are fixed to the base unit with chemical binding agent

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 3

a ring formed of combustible material is arranged to hold the fins, in the retracted position, fixed to the base unit; the ring is made of propellant

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 4

the fins are fixed to the base unit with a shear stud mounted between the fins and the base unit

Methodology Applied
Scientific EffectMechanical fastening: Mechanical Fastener

Data Source

PatentEP2697598B1Fin deployment mechanism and projectile with such a mechanism
Publication Date: 2017.12.13 BAE SYSTEM BOFORS AB
  • EP2697598B1 patent drawingFigure 1~2
  • EP2697598B1 patent drawingFigure 3~4
  • EP2697598B1 patent drawingFigure 5

AI summary

The invention relates to a fin deployment mechanism (1) comprising a base unit (3), deployable fins (8) movably arranged on the base unit (3) and, in the retracted position, bearing against the base unit (3), as well as a gas-generating device, in which the fins in the retracted position are fixed to the base unit, and in which at least one gas duct (6, 7) is arranged in the base unit (3) so as to conduct pressurized gas generated by the gas-generating device to the bottom side of the fins (8), which in the retracted position bear against the base unit (3), in order to create a force which acts on the fins (8) for deployment of the same (8'). The invention further relates to an artillery projectile comprising a fin deployment mechanism.