Projectile Fin Locking via Rotatable Partial Fin and Support Edge

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Solution Overview

Problem

Existing projectile tail fin designs generate significant aerodynamic drag due to unwanted airflow and often fail to securely lock in the deployed position, especially in harsh environments.

Innovation Solution

A projectile design featuring rotatably attached partial fins that form a complete fin with a support structure, including a leaf spring for locking and vibration dampening, which reduces drag and enhances locking security by forming an aerodynamic edge and closing cavities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If existing tail fin designs are used to enable movement from stored to deployed position, then fin deployability is improved, but aerodynamic drag increases due to separated or recirculated air flow

Engineering Contradiction:
Improvefin deployabilityVSAvoidaerodynamic drag
Core Design Contradiction:
Duration of action of moving objectVSLoss of energy

Solution Approach 1:

The tail fin is divided into two segments: a stationary support fin and a movable partial fin. This segmentation allows the partial fin to rotate into position without requiring complex deployment structures, thereby reducing aerodynamic drag while maintaining deployability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of having a large fin that folds or retracts, the invention uses a partial fin that rotates into position. This inverted approach—using a smaller component that moves into place rather than a large component that moves out of the way—eliminates the need for complex deployment mechanisms and reduces aerodynamic drag.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of operation

If existing locking mechanisms are used for fin deployment, then fin positioning is improved, but reliability deteriorates in harsh environments due to failure to capture fin securely

Engineering Contradiction:
Improvefin positioningVSAvoidlocking security
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention extracts the locking function from complex mechanical locking mechanisms and implements it through a simple geometric feature: the aerodynamic edge of the partial fin engages with the support fin structure. This extracted locking mechanism eliminates vulnerable components while maintaining secure fin positioning.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention converts the harmful aerodynamic forces that typically cause drag into a beneficial locking mechanism. The aerodynamic pressure differential created during flight naturally pushes the partial fin against the support fin, securing it in place without requiring additional locking components.

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

3Adaptability or versatility

If existing fin structures are used, then fin movement capability is improved, but drag increases due to excessive free play and recirculated air flow

Engineering Contradiction:
Improvefin movement capabilityVSAvoidaerodynamic drag
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The partial fin is designed to be dynamic, rotating from a stowed position to a deployed position during flight. This dynamic configuration allows the fin to adapt to different flight phases while maintaining a streamlined profile during cruise, reducing drag while preserving movement capability.

Inventive Principle:
Principle #15Dynamics

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 design minimizes aerodynamic drag and ensures secure fin locking in various environments, enhancing the projectile's range and reliability by reducing drag and preventing malfunctions due to wear, ice, or debris.

Implementation Method 1

The support 14 locks the partial fin 16 in place when the partial fin 16 is in the deployed position to form the complete fin 18. The leaf spring 15 provides vibration dampening to help reduce the effects of any vibrations that are generated on the partial fin 16 during flight of the projectile 10.

Methodology Applied
Scientific EffectVibration dampening: Damping

Implementation Method 2

The support 14 forms a portion of the front edge 20 of the complete fin 18 when the partial fin 16 is in the deployed position. The support 14 locks the partial fin 16 in place when the partial fin 16 is in the deployed position to form the complete fin 18.

Methodology Applied
Scientific EffectAerodynamic drag reduction: Drag

Data Source

PatentEP2598833B1Aerodynamic fin lock for adjustable and deployable fin
Publication Date: 2018.04.25 RAYTHEON CO
  • EP2598833B1 patent drawingFigure 1
  • EP2598833B1 patent drawingFigure 2
  • EP2598833B1 patent drawingFigure 3

AI summary

Some embodiments pertain to a projectile that includes a body and a support attached to the body. The projectile further includes at least one partial fin that is rotatably attached to the support such that the partial fin moves between a stowed position and a deployed position. The support moves relative to the partial fin as the partial fin moves between the stowed position and the deployed position such that the partial fin and the support form a complete fin when the partial fin is in the deployed position. The support may form a portion of the front edge of the complete fin when the partial fin is in the deployed position. The support may lock the partial fin in place when the partial fin is in the deployed position.