Projectile Fin Blocking Using Elastic Roller-Ramp Jamming
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Solution Overview
Problem
Existing technologies for blocking projectile fins are unreliable and unstable, particularly when fins deploy around axes parallel or perpendicular to the projectile's longitudinal axis, leading to partial folding and instability due to inadequate locking mechanisms.
Innovation Solution
A device featuring a recess with a shape of revolution, such as a roller or ball, housed by an elastic means like a wave spring or leaf spring, which ensures permanent contact with a ramp surface, preventing fin retraction by jamming between the surfaces, thus providing reliable locking in both deployment configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blade flexes to block fin folding, then fin locking is achieved, but bracing is not always obtained perfectly and quickly causing partial folding
Solution Approach 1:
The invention extracts the locking function from a complex bracing mechanism and implements it through a simple blade element that flexes during deployment and then braces against the fin foot. This blade is positioned to engage with the fin foot in a way that provides reliable locking without requiring complex additional components.
Solution Approach 2:
The blade is designed to be dynamic during deployment - it flexes initially to allow fin unfolding, then braces itself automatically when the fin reaches its deployed position. This dynamic behavior ensures reliable locking while maintaining simplicity, as the blade transitions from a flexible state during deployment to a rigid braced state for locking.
2Ease of operation
If radial thrust of a ball is used for locking, then fin deployment is achieved, but functional clearances cause fin oscillation and instability
Solution Approach 1:
The invention introduces a blade as an intermediary element between the fin foot and the projectile body. This blade mediates the locking action by flexing during deployment to allow easy fin extension, then bracing against the fin foot to provide stable locking. The blade acts as a mechanical mediator that converts the deployment motion into a stable locked position without causing oscillation.
3Reliability
If an inertial weight is used to hold fin folded, then fin locking during acceleration is achieved, but device complexity increases and weight displacement can fail
Solution Approach 1:
The blade is designed to be self-servicing during fin deployment and locking. It automatically flexes during deployment and self-braces when the fin reaches its deployed position, requiring no external control mechanisms or inertial weights. The blade's own elastic properties enable it to perform both the deployment facilitation and the locking functions, eliminating the need for complex inertial weighting systems.
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
Ensures consistent and reliable blocking of fins in both extended and retracted positions, enhancing stability and range by preventing oscillation and rebound, regardless of fin axis orientation.
Implementation Method 1
the elastic means ensures permanent contact of the shape of revolution with the ramp and the other surface by pushing the shape of revolution against both the ramp and the other surface
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a blocking device (10) for a fin (3) of a projectile (100), said fin (3) having a fin root (3a) pivoting about a pivot (4) secured to the body (2) of the projectile (100) between a retracted fin position and an extended fin position, said device (10) being characterized in that it has at least one recess (5) accommodating at least one rotationally symmetric form (7) pushed by an elastic means (6) between a first surface (S1) borne by the fin (3) and a second surface (S2) borne by the body (2) of the projectile, at least one of the two surfaces (S1, S2) forming a ramp (5a) that converges towards the other surface in order to cause the rotationally symmetric form (7) to be trapped between the two surfaces.