Segmented Polymer Projectile for Nonlethal Cartridge Fouling Reduction
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Solution Overview
Problem
Existing nonlethal cartridges for firearms face issues with rapid plastic fouling in the barrel due to the soft polymer front shell, leading to compromised ballistic performance and reliability, premature aging of the marking compound affecting accuracy, and increased logistical burdens from wax or oil-based compounds.
Innovation Solution
A nonlethal cartridge design featuring a polymer base projectile portion for spin stabilization and a softer polymer front shell with a circular locking rib feature to minimize fouling, combined with a sabot for propellant gas expansion, and a design that maintains the marking compound's shelf life by sealing it within the projectile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the front shell is made of soft polymer to absorb impact energy, then impact energy absorption is improved, but plastic fouling of the barrel increases
Solution Approach 1:
The projectile is divided into two distinct parts: a soft polymer front shell for impact energy absorption and a harder polymer base for structural integrity and reduced fouling. This segmentation allows each part to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the projectile are made from materials with different properties. The front shell uses soft polymer (e.g., polyethylene) for energy absorption, while the base uses harder polymer for structural support and reduced barrel fouling, creating local quality variations that address multiple requirements simultaneously.
2Manufacturing precision
If the front shell is made thin and soft for reliable deformation, then projectile deformation is improved, but structural robustness within the cartridge deteriorates
Solution Approach 1:
The projectile structure is segmented into a thin soft front shell and a stronger base, allowing the shell to be thin enough for reliable deformation while the base provides the necessary structural robustness to prevent dislodgement during loading and feeding.
Solution Approach 2:
The projectile uses composite construction with two different polymer materials: soft polymer for the front shell and harder polymer for the base. This composite structure combines the deformation reliability of soft material with the structural strength of harder material.
3Ease of operation
If water-based marking compound is used for easy washability, then cleaning ease is improved, but shelf life deteriorates due to moisture evaporation
Solution Approach 1:
The front shell acts as a flexible barrier that seals the water-based marking compound, preventing moisture evaporation while allowing the compound to remain water-based for easy washability. The shell integrity preserves the compound's water content throughout storage.
Solution Approach 2:
The marking compound is pre-sealed within the front shell before storage, preventing moisture loss in advance. This preliminary sealing action ensures the compound maintains its water-based properties and shelf life without requiring frequent replacement.
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 significantly reduces plastic fouling, maintains consistent projectile velocity and accuracy, and extends the shelf life of the marking compound, ensuring reliable performance and reduced maintenance needs.
Implementation Method 1
The polymer base projectile portion is configured to engage the rifling of the barrel to impart spin stabilization to the projectile when propelled from the sabot in response to the expansion of the propellant gas
Implementation Method 2
A nonlethal projectile is configured to be propelled from the sabot through the barrel of the firearm in response to expansion of propellant gas
Implementation Method 3
The polymer front shell projectile portion is configured to deform upon impact to absorb impact energy
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Nonlethal cartridges adapted to be chambered in a firearm having a barrel that includes rifling are provided. In one example, the cartridge includes a cartridge case and a sabot that is telescopically coupled to the cartridge case and that has a sabot mouth. A projectile includes a polymer base projectile portion disposed in the sabot mouth. A polymer front shell projectile portion is coupled to the polymer base projectile portion and has an outer surface that includes a circular locking rib feature that forms an interference fit with the sabot mouth. The polymer base projectile portion is configured to engage the rifling of the barrel to impart spin stabilization to the nonlethal projectile when propelled from the sabot in response to the expansion of a propellant gas.