Shotshell Wad Fin Deployment for Stable Flight
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Solution Overview
Problem
Conventional shotgun wad designs with forward wall segments and flared propellant cups lead to inconsistent shot patterns due to instability and potential damage from ported chokes, causing the wad to yaw or tumble, affecting the shot pattern and performance.
Innovation Solution
A shotgun shell wad design featuring a polymer wad with a forward shot cup and a rearward propellant cup, incorporating enhanced fin deployment mechanisms such as gussets and an axially movable disk to maintain fins in an open position, ensuring stability across various barrel pressures and choke types, and providing air circulation through axial slits to prevent shot compaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the wad remains with the shot during flight to extend effective range, then the effective range is extended, but the wad flight becomes unstable and yaws causing worsened patterning
Solution Approach 1:
The wad design incorporates dynamic fin deployment where fins transition from a stowed position during muzzle passage to a deployed position during flight. This dynamic adjustment allows the wad to maintain stability over extended ranges without the continuous instability that plagues conventional designs. The fins are initially folded forward during high-pressure muzzle passage, then deploy as pressure drops, providing aerodynamic stability only when needed for extended flight.
Solution Approach 2:
The invention changes the aerodynamic parameters of the wad during flight by deploying fins that alter the center of pressure and drag characteristics. This parameter change enables the wad to maintain stable flight attitudes over extended ranges. The fins are positioned and dimensioned to provide appropriate aerodynamic moments that counteract yaw and maintain straight-line flight, directly addressing the stability issue while enabling extended range.
2Speed
If forward wall segments and flared propellant cups are used to slow the wad, then separation point is moved closer to muzzle, but shot pattern consistency deteriorates due to wad instability and damage from ported chokes
Solution Approach 1:
The fin deployment mechanism provides dynamic control over wad deceleration. Rather than using fixed geometric features that cause immediate and potentially damaging deceleration, the fins deploy progressively as the wad exits the barrel, providing controlled, progressive deceleration. This dynamic approach maintains shot pattern consistency while achieving reliable separation, avoiding the damage issues associated with conventional flared cups and ported chokes.
3Adaptability or versatility
If conventional wad designs are used with ported chokes, then the wad can pass through the choke, but the wad may be damaged or cause inconsistent patterns due to interaction with choke ports
Solution Approach 1:
The fins are pre-configured in a stowed position that allows smooth passage through ported chokes without interaction. The fins remain folded forward during muzzle passage and choke traversal, presenting a streamlined profile that avoids damage from choke ports. Only after safely clearing the choke do the fins deploy to provide flight stability, eliminating the reliability issues associated with conventional wad-choke interactions.
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 enhanced wad design achieves consistent fin flaring and improved shot pattern stability, extending effective range and reducing the likelihood of wad instability and damage from ported chokes, resulting in more accurate and consistent shot dispersal.
Implementation Method 1
The propellant cup portion with fins flares when the wad with shot leaves the muzzle due to high muzzle pressure behind the wad
Implementation Method 2
aerodynamic drag on the cup portion or the flaring of the fins slows the wad separating the wad from the slug or shot
Data Source
AI summary
A shotgun shell has a polymer wad with a forward shot cup portion and a rearward propellant cup, the wad in a casing, shot in the shot cup, propellant in the propellant cup, and a primer in a head of the casing. The propellant cup having a plurality of fins extending rearwardly that open to a deployed position upon firing and the shot cup having a plurality of circumferentially spaced axially aligned linear slit segments that permit air to circulate and permit expansion of the shot cup.