Projectile Guiding Fin Assembly With Adaptive Pitch Control

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Solution Overview

Problem

Existing projectile guiding kits face challenges in balancing cost and accuracy, as high-cost kits dissipate less kinetic energy but are inefficient, while low-cost kits dissipate more energy, shortening the projectile's range and reducing accuracy due to fixed fin angles that fail to adapt to changing flight parameters.

Innovation Solution

A guiding fin assembly with pivotally connected fins and adjustable pitch angles, controlled by relative speed control units and springs, allowing for dynamic adjustment of aerodynamic forces and torque to maintain stability and accuracy across varying flight conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If fixed angle fins are used in low-cost guiding kits, then cost is reduced, but energy dissipation increases and accuracy deteriorates

Engineering Contradiction:
ImprovecostVSAvoidenergy dissipation
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The fin assembly incorporates pivotally connected fins that can dynamically adjust their pitch angles during flight. The relative speed control units and springs enable the fins to automatically adapt to changing flight parameters (airspeed and density), transforming the static fin structure into a dynamic one that optimizes aerodynamic performance throughout the trajectory, thereby reducing energy dissipation while maintaining low cost.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the pitch angle parameter of the fins dynamically during flight. By using springs and relative speed control units, the system automatically adjusts the fin angles to match changing airspeed and density conditions, optimizing the balance between lift and drag at different phases of flight, which reduces overall energy dissipation.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If fixed angle fins are used, then device complexity is reduced, but adaptability to changing flight parameters deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidadaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The fin assembly is designed to automatically adapt to changing flight conditions without external control systems. The springs and relative speed control units create a self-regulating mechanism where the fins naturally adjust their angles in response to aerodynamic forces and speed changes, providing adaptability through passive self-adjustment rather than active control.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The pivotally connected fins create a dynamic structure that passively responds to flight conditions. As airspeed and density change during trajectory, the aerodynamic forces on the fins cause them to naturally adjust their pitch angles, providing continuous adaptation to varying flight parameters without adding complex control systems.

Inventive Principle:
Principle #15Dynamics

3Reliability

If high anti-rotational power is provided at trajectory beginning, then spin control is improved, but energy dissipation increases

Engineering Contradiction:
Improvespin controlVSAvoidenergy dissipation
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The relative speed control mechanism provides spin control in a periodic or phased manner rather than continuously at maximum power. The springs and controllable units adjust the anti-rotational power delivery to match the actual needs at different trajectory phases, providing high power when needed (initial spin control) and reducing power as flight progresses, thereby minimizing overall energy dissipation.

Inventive Principle:
Principle #19Periodic action

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 solution provides a cost-effective and accurate guiding system that maintains consistent torque and lift, reducing energy dissipation and extending the projectile's range by dynamically adjusting fin angles to match changing airspeed and density, thereby improving the CEP and cost ratio.

Implementation Method 1

two return springs, each spring being operably connected to a respective guiding fin, wherein said springs are configured to allow movement correspondingly to aerodynamic pressure on said fins

Methodology Applied
Scientific EffectAerodynamic pressure: Drag

Implementation Method 2

a relative speed control unit operable between said rear main unit and said front main unit and capable of providing spin braking force to slow the relative speed of rotation

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3388777B1Low cost guiding device for projectile
Publication Date: 2022.04.20 ELBIT SYST ROKAR LTD
  • EP3388777B1 patent drawingFigure 1A~1D
  • EP3388777B1 patent drawingFigure 2A~2C
  • EP3388777B1 patent drawingFigure 3

AI summary

A guiding assembly is adapted to be connected to a projectile and comprising a rear main unit adapted to be connected to the front end of the projectile, and a front main unit rotatably connected at its rear end to the front end of the rear main unit. The front main unit is adapted to rotate about a central longitudinal axis. A relative speed control unit is operable between the rear main unit and the front main unit and capable of providing spin braking force to slow the relative speed of rotation of the front main unit. An at least one guiding fin radially extends from the front main unit. The pitch angle of the fin is controllable by a return spring connected to the fin so that the pitch angle of the fin is growing as the aerodynamic pressure on the fin lowers and it is growing smaller as the aerodynamic pressure on the fin gets bigger.