Electromagnetic Projectile Spin Stabilization With Non-Axisymmetric Fields
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Solution Overview
Problem
Electromagnetic accelerators, such as coilguns, lack the ability to impart rotational spin on projectiles due to their smoothbore design, leading to reduced accuracy and limited practical application, especially in portable devices.
Innovation Solution
A mechanism that imparts rotational spin to projectiles using a non-axisymmetric magnetic field generated by a coilgun, which applies a torque to the armature through a combination of shims and coils, allowing for simultaneous or sequential linear and rotational acceleration without mechanical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electromagnetic accelerators use a smoothbore design, then the device complexity is reduced and manufacturing is easier, but the projectile cannot be stabilized by spin and accuracy deteriorates
Solution Approach 1:
The patent applies asymmetry by introducing a non-axisymmetric magnetic field configuration through strategically positioned shims (magnetic shielding elements) within the coilgun barrel. These shims create asymmetric magnetic flux distribution that exerts torque on the projectile, imparting spin stabilization without requiring mechanical rifling. This resolves the contradiction by achieving spin stabilization (improving accuracy) while maintaining the simplicity of the smoothbore design (preserving ease of manufacture).
Solution Approach 2:
The patent replaces the mechanical rifling system (grooves or polygonal turning in the barrel) with an electromagnetic field-based spin impartation system. Instead of mechanically engaging the projectile through physical contact with grooves, the system uses non-axisymmetric magnetic fields to induce rotational motion. This substitution maintains manufacturing simplicity (no mechanical rifling required) while achieving the desired spin stabilization for accuracy.
2Manufacturing precision
If electromagnetic accelerators impart spin onto projectiles, then accuracy is improved, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The patent merges the spin-imparting function with the existing coilgun coil structure by integrating shims into the barrel assembly. Rather than adding separate spin-imparting mechanisms (such as helical rails or aerodynamic fins), the system combines magnetic field manipulation with the linear acceleration function. The shims are positioned within the coil structure to create non-axisymmetric fields that simultaneously contribute to both linear propulsion and rotational stabilization, thereby improving accuracy without proportionally increasing device complexity.
Solution Approach 2:
The shims act as intermediary elements that mediate between the electromagnetic field and the projectile. These magnetic shielding elements modify the field distribution without requiring direct mechanical contact or complex structural changes to the coilgun. The shims serve as a simple intermediary component that transforms the symmetric magnetic field into a non-axisymmetric configuration, enabling spin impartation with minimal added complexity.
3Ease of operation
If portable coilguns are designed with minimal weight, then ease of operation is improved, but the ability to impart spin and achieve accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the magnetic field distribution through the placement and configuration of shims with specific magnetic properties. By modifying the magnetic field parameters (flux distribution, field strength variation) rather than changing the mechanical structure, the system achieves spin stabilization in portable devices. This approach maintains the lightweight design (preserving ease of operation) while introducing the necessary spin impartation capability (improving accuracy) through electromagnetic parameter optimization.
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
Enhances the accuracy of electromagnetic projectiles by stabilizing their flight through spin, maintaining the advantages of silent operation and simplicity while reducing wear and complexity, suitable for portable devices.
Implementation Method 1
a ferromagnetic armature to high velocities by sequentially turning on and off high-amperage electromagnet coils in a sequence to apply an accelerating force to an armature throughout its travel
Implementation Method 2
coils which drive an armature to high velocities by sequentially turning on and off high-amperage electromagnet coils in a sequence to apply an accelerating force to an armature throughout its travel
Data Source
AI summary
An electromagnetic accelerator device which is configured to impart spin to projectiles fired from it. Various methods to accomplish this stabilization are proposed. The spin may be imparted physically using friction, inductively using an alternating magnetic field or inducing eddy currents in an armature, or by shaping the magnetic field or armature within the barrel of the device appropriately. The magnetic field(s) within such a device may be configured to impart a linear, as well as a rotational force, upon an armature which may be non-circular in cross-sectional profile, or non-axisymmetric in physical shape or material properties.