Reduced-Stiffness Barrel-Fired Projectile With Internal Core Grooves
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Solution Overview
Problem
Rifled barrel fired projectiles face challenges in maximizing muzzle velocity and reducing barrel wear due to high metal-to-metal friction and stiffness, while traditional grooving techniques increase aerodynamic drag and are difficult to implement with conventional jacketed projectiles.
Innovation Solution
Designing projectiles with circumferential grooves in the interior core, covered by a metal jacket, allows material displacement during firing, reducing radial stiffness and friction, thus enhancing muzzle velocity and barrel lifespan without significantly increasing drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If circumferential grooves are added to the exterior body of a projectile, then metal to metal contact area is reduced and friction is reduced, but aerodynamic drag increases
Solution Approach 1:
The grooves are moved from the exterior surface to the interior core of the projectile, changing the spatial dimension from external to internal. This allows the grooves to reduce friction during barrel engagement without affecting the external aerodynamic profile of the projectile.
Solution Approach 2:
The circumferential grooves are nested within the interior core of the projectile, covered by the metal jacket. This nesting allows the friction-reducing grooves to exist inside the projectile structure without being exposed to the external environment, thus maintaining aerodynamic integrity.
2Speed
If grooves are added to reduce radial stiffness and energy requirement, then muzzle velocity improves, but manufacturing complexity increases
Solution Approach 1:
The circumferential grooves are pre-formed in the interior core during the manufacturing process, before the projectile is fired. This preliminary action ensures the grooves are already in place to reduce radial stiffness and energy requirements during barrel engagement, improving muzzle velocity without requiring complex modifications during or after firing.
3Strength
If high stiffness materials like steel or copper are used in the projectile core, then strength and penetration improve, but barrel wear increases due to high friction
Solution Approach 1:
The projectile core is designed with circumferential grooves that create localized regions of reduced stiffness at the barrel engagement interface, while the bulk material maintains its high strength properties. This local modification allows high stiffness materials like steel or copper to be used without proportionally increasing barrel wear, as the grooves reduce the contact area and friction.
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 improves muzzle velocity, accuracy, and barrel lifespan by reducing friction and heat while maintaining aerodynamic integrity, particularly effective for projectiles with higher stiffness materials like copper and steel.
Implementation Method 1
such grooves can reduce the overall radial stiffness of the projectile by allowing barrel-engaging material to displace into the circumferential grooves
Implementation Method 2
reduce the needed energy to deform the projectile surface by the barrel rifling
Implementation Method 3
such grooves can reduce metal to metal contact between a projectile and a rifled barrel from a reduction in surface area on the projectile that directly contacts the rifled barrel during firing
Data Source
AI summary
In various embodiments, a projectile includes a projectile body including a tail portion, a nose portion, a barrel engaging portion between the nose portion and the tail portion, and a metal jacket that defines an exterior of the projectile that surrounds an interior solid core. In one or more embodiments the projectile includes one or more circumferential grooves defined in the interior core portion, each of the one or more circumferential grooves covered by and positioned adjacent to the metal jacket and within the barrel-engaging portion. In various embodiments, during firing of the projectile, the one or more circumferential grooves define a void that allows material of one or more of the metal jacket and interior solid core to displace into the void for reduction in radial stiffness to the projectile in the barrel engaging portion.