Projectile Plastic Base Wad Rifling Friction
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Solution Overview
Problem
Large bore military guns and fully automatic machine guns experience reduced rapid fire ability due to heat buildup and projectile tumbling caused by metal-to-metal friction with rifling, and common ejection issues lead to weapon failures.
Innovation Solution
A projectile system comprising a metal body with a plastic base wad that engages the rifling to impart rotation and reduce friction, using a central cavity with a one-way valve to trap expanding gas for propulsion, and an ignition system for explosive material, eliminating the need for case ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal projectiles engage rifling grooves to create gas seal and provide rotation, then the projectile achieves stable flight and sealing, but metal-to-metal friction causes heat buildup and reduces rapid fire ability
Solution Approach 1:
A plastic base wad is introduced as an intermediary component between the projectile and rifling. The base wad engages the rifling grooves to create the gas seal and impart rotation, while the projectile body does not contact the rifling directly. This mediator eliminates metal-to-metal friction and heat buildup while maintaining the necessary sealing and spinning functions.
Solution Approach 2:
The projectile uses a composite structure combining metal body with a plastic base wad. The plastic material at the base provides low-friction engagement with the rifling, reducing heat generation during rapid firing, while the metal body maintains structural integrity and aerodynamic properties.
2Speed
If projectiles are base-heavy to engage rifling, then rotation is achieved, but the base-heavy configuration causes tumbling during flight
Solution Approach 1:
The projectile is segmented into distinct functional zones: a forward metal body containing the payload and aerodynamic features, and a rear plastic base wad for rifling engagement. This segmentation allows the front-heavy configuration to provide flight stability while the base wad provides the necessary rotation without causing tumbling.
Solution Approach 2:
Different parts of the projectile have different mass distributions optimized for their specific functions. The metal body is designed with appropriate mass concentration for stable flight, while the plastic base wad is lightweight and engages the rifling to impart rotation without disrupting the overall flight stability.
3Reliability
If conventional ejection systems are used to remove spent cartridges, then spent cases are ejected, but ejection components fail and cause weapon jams and deformations
Solution Approach 1:
The invention extracts and eliminates the traditional ejection system entirely. The plastic base wad serves multiple functions including rifling engagement, gas sealing, and acts as a disposable component that is ejected with the spent cartridge, removing the need for separate ejection mechanisms and their associated failure modes.
Solution Approach 2:
The plastic base wad is a multi-functional component that combines gas seal, rifling engagement for rotation, and ejection function. This consolidation of multiple functions into a single component simplifies the overall system and eliminates the complex ejection hardware that is prone to failure.
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
Enables more rapid and sustained firing with reduced heat buildup and friction, improving reliability by avoiding metal-to-metal contact and enhancing projectile aerodynamics through gas expansion and base wad separation.
Implementation Method 1
the plastic base wad fully engages the rifling, imparting rotation to the metal projectile
Implementation Method 2
expanding gas in firing the projectile with the base wad enter and pressurize the central cavity in the metal body
Implementation Method 3
a one-way valve in the central bore in the plastic base wad, allowing gas into the central cavity of the metal body, but preventing gas from exiting the cavity through the central bore
Implementation Method 4
igniting an explosive charge to propel the combination of the metal body and the plastic base wad along the rifled barrel
Implementation Method 5
two electrodes in contact with the magnesium foil, the electrodes connected to opposite terminals of a battery through an ignition switch, such that closing the ignition switch closes an electric circuit through the magnesium foil, igniting the explosive material
Data Source
AI summary
A projectile system has a projectile with a metal body having a first outside diameter, a forward end and a rearward end, a plastic base wad engaged at the rearward end, the plastic base wad of solid plastic having a first length and a second outside diameter, greater than the first outside diameter, and a rifled barrel having a third inside diameter at the tips of the rifling, the third inside diameter greater than the first outside diameter but less than the second outside diameter, and a fourth diameter at the root of the rifling greater than the second outside diameter. With the projectile translating along the rifled barrel, the metal body passes inside the rifling, avoiding metal to metal friction, while the plastic base wad fully engages the rifling, imparting rotation to the metal projectile.