Jacketed Projectile Base Cavity for Stability
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Solution Overview
Problem
Conventional long-nose projectiles face a tradeoff between achieving high ballistic coefficients and maintaining stability during flight, as increased nose length enhances ballistic coefficient but decreases stability due to an unfavorable center of gravity to center of pressure ratio, leading to increased susceptibility to yaw and reduced maximum velocity.
Innovation Solution
A polymer jacketed projectile design featuring a recessed cavity at the base end filled with a polymer protrusion, which moves the center of gravity forward, reducing overall weight and stabilizing the projectile, while maintaining the benefits of a longer ogive region, and optionally incorporating a boat tail for further drag reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nose length of the projectile is increased to enhance the ballistic coefficient, then the ballistic coefficient is improved, but the stability during flight deteriorates due to an unfavorable center of gravity to center of pressure ratio
Solution Approach 1:
The projectile is divided into distinct segments: a long ogive nose section for high ballistic coefficient, a cylindrical midsection, and a boat tail base. The recessed cavity at the base further segments the mass distribution. This segmentation allows each section to be optimized independently - the long nose for aerodynamics and the rear-weighted base for stability.
Solution Approach 2:
The invention addresses the stability problem by moving along the longitudinal dimension - specifically by creating a recessed cavity at the base end of the projectile. This dimensional modification (adding depth to the base) allows redistribution of mass along the length of the projectile, moving the center of gravity rearward to achieve proper balance with the center of pressure.
2Reliability
If the nose length of the projectile is increased to achieve higher ballistic coefficient, then the ballistic coefficient is improved, but the maximum velocity decreases due to increased overall projectile weight
Solution Approach 1:
Material is extracted from the base end of the projectile by creating a recessed cavity. This removal of mass from the rear section reduces the overall weight of the projectile while preserving the long nose geometry needed for high ballistic coefficient. The extraction is targeted specifically at the base to maintain the aerodynamic profile.
Solution Approach 2:
The recessed cavity creates a local change in mass distribution at the base end of the projectile. Rather than uniformly reducing weight, the local modification at the base selectively removes material where it least impacts aerodynamic performance, thereby reducing overall weight while maintaining the long nose geometry for high ballistic coefficient.
3Stability of the object's composition
If a recessed cavity is created at the base end to move the center of gravity forward and reduce overall weight, then flight stability and maximum velocity are improved, but the manufacturing complexity increases
Solution Approach 1:
The recessed cavity is integrated with the boat tail base design, combining two features (the cavity and the tapered base) into a unified geometric form. This merging allows the cavity to be formed as part of the base machining process rather than as a separate operation, reducing manufacturing complexity.
Solution Approach 2:
The recessed cavity serves multiple functions simultaneously: it moves the center of gravity to improve stability, reduces overall projectile weight to increase velocity, and can be integrated with the boat tail design to streamline manufacturing. This multi-functionality justifies the additional manufacturing step by delivering multiple performance benefits from a single feature.
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 design achieves higher maximum velocities and improved flight stability by balancing the center of gravity and center of pressure, reducing the overturning moment and enhancing aerodynamic stability, thus achieving high ballistic coefficients with increased resistance to yaw.
Implementation Method 1
A polymer jacket is formed around the core. The polymer jacket includes a protrusion, made of the same or different polymer material as the jacket, which fills the recessed cavity. The protrusion of the polymer jacket fills the recessed cavity, thereby moving the center of gravity in a forward direction.
Implementation Method 2
The internal rifling of the barrel engages the largest diameter section of the projectile as it is propelled out of the firearm to provide rotational spin to the projectile. The rotational spin of the projectile creates gyroscopic forces that resist the overturning moment.
Implementation Method 3
The base can be formed as a flat base, e.g., cylindrical ending in a flat plane, or may be formed with a boat tail, e.g., an inward taper at the base end. The boat tail design is known to decrease the wind drag a projectile will experience along its flight path and increase accuracy at longer ranges.
Implementation Method 4
The internal rifling of the barrel engages the largest diameter section of the projectile as it is propelled out of the firearm to provide rotational spin to the projectile.
Implementation Method 5
The rotational spin of the projectile creates gyroscopic forces that resist the overturning moment.
Implementation Method 6
A recessed cavity is defined at the base end and extends into the core body. The recessed cavity reduces the amount of material of the core body, thus lessening the overall weight of the core in comparison to conventional long range projectiles.
Data Source
AI summary
A long range jacketed projectile has a cavity defined in the base end of the projectile core that is substantially filled with polymer material during the jacketing process. The cavity is configured to lighten the core, which lightens the overall weight of the projectile, and move the center of gravity closer to the center of pressure when compared to a conventional long range projectile. The polymer jacket lightens the projectile weight, which when combined with the lighter core, allows the projectile to attain a flatter trajectory at increased maximum velocities.