Steerable Spin-Stabilized Projectile Inertial Guidance

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Solution Overview

Problem

Existing guidance systems for spin-stabilized projectiles are expensive, complex, and prone to damage, and they often require the deployment of fins or thrust-producing devices, which are problematic.

Innovation Solution

The use of inertial properties for steering by tilting an internal counter-rotating mass within the projectile's cavity relative to its hull, with electromagnets on the inner surface to selectively control the mass's tilt and rotation, allowing for steering without external control surfaces or thrust-producing devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional guidance systems are used for spin-stabilized projectiles, then guidance functionality is achieved, but the system becomes expensive, complex, and prone to damage

Engineering Contradiction:
Improveguidance system reliabilityVSAvoidguidance system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical guidance systems with an inertial mass tilting mechanism. Instead of using traditional fins, rockets, or electronic guidance components that are prone to damage in spin-stabilized projectiles, the invention uses a simple inertial mass that tilts relative to the projectile body to change flight direction. This mechanical substitution eliminates complex guidance systems while maintaining steering capability, directly resolving the contradiction between reliability and complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If control surfaces or thrust-producing devices are deployed for steering, then directional control is achieved, but the system becomes more complex and vulnerable to damage during launch or flight

Engineering Contradiction:
Improvedirectional control capabilityVSAvoidcontrol mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts the essential steering function from complex control surfaces and thrust-producing devices, retaining only the core inertial mass tilting mechanism. By removing unnecessary components like deployable fins and rocket thrusters that complicate the system and increase vulnerability, the invention achieves directional control through a simplified inertial mass system, resolving the contradiction between ease of operation and device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

3Adaptability or versatility

If traditional guidance systems with fins or rockets are used, then steering is possible, but the system requires deployment mechanisms that are problematic in spin-stabilized projectiles

Engineering Contradiction:
Improvesteering capabilityVSAvoidmanufacturing simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent substitutes traditional deployment mechanisms (fins, rockets) with a passive inertial mass tilting system that requires no complex deployment mechanisms. The inertial mass simply tilts in response to gravitational and aerodynamic forces, providing steering capability without requiring any active deployment systems. This substitution maintains adaptability while dramatically simplifying manufacturing, as the system consists of basic mechanical components that can be easily integrated into existing projectile designs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This approach results in a cost-effective, robust, and simple guidance system that enhances the range and accuracy of spin-stabilized projectiles, enabling better engagement of moving targets without requiring special modifications to current weapons systems.

Implementation Method 1

The internal mass is counter-rotating relative to hull in the direction opposite to the spin of the projectile

Methodology Applied
Scientific EffectCounter-rotation: Angular Momentum

Implementation Method 2

the projectile, has electromagnets on an inner surface of a hull, wherein voltage is selectively applied to the electromagnets to tilt and/or rotate a mass within a cavity in the hull

Methodology Applied
Scientific EffectElectromagnetic force: Electromagnet

Implementation Method 3

The projectile uses inertial properties for steering. The inertial steering involves tilting of an internal mass that is in a cavity in a body or hull of the projectile toward and away from a longitudinal axis of the body

Methodology Applied
Scientific EffectInertial properties: Inertia

Data Source

PatentEP2356398B1Steerable spin-stabalized projectile and method
Publication Date: 2014.05.07 RAYTHEON CO
  • EP2356398B1 patent drawingFigure 1
  • EP2356398B1 patent drawingFigure 2
  • EP2356398B1 patent drawingFigure 3~4

AI summary

A spin-stabilized projectile has its course controlled by counter rotation of an internal mass about a longitudinal axis of the projectile. The internal mass may be a boom within a cavity of an external body of the projectile. The internal mass may be tiltable relative to the hull, and may be configured to counter rotate relative to the hull about the axis of the hull. The counter-rotation may keep the boom in a substantially same orientation relative to the (non-spinning) environment outside of the projectile. The positioning of the boom or other weight within the projectile thus may be used to steer the projectile, by providing an angle of attack to the projectile hull. A magnetic system may be used to counter rotate the boom or other weight. The projectile may have a laser guidance system to aid in steering the projectile toward a desired aim point.