Sub-caliber Projectile Tip Design for Oblique Impact

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Solution Overview

Problem

Sub-caliber projectiles experience reduced piercing performance due to interference between the bar and the crater choke when impacting targets at an angle, caused by the diameter mismatch between the bar and the crater created by the conventional head structure.

Innovation Solution

A sub-caliber projectile design featuring a conical portion with a heating-resistant tip of less than half the diameter of the bar, connected by a lightweight support structure that has no ballistic effects, ensuring the bar's flat front face can impact the target without disturbance, thereby maintaining high piercing efficiency even at oblique angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a conventional head structure with piercing nuclei smaller than the bar diameter is used, then the projectile can achieve high bar speed (1700 m/s), but the crater diameter is enlarged with a reduced diameter choke at entry, causing interference between the bar and choke edge during oblique impact which reduces piercing performance

Engineering Contradiction:

Improvebar speedVSAvoidpiercing performance during oblique impact

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The invention removes the conventional piercing nuclei from the head structure and replaces them with a single tip having a diameter less than half the bar diameter. This extraction of the problematic multi-nuclei configuration eliminates the source of crater expansion while maintaining the high-speed piercing capability through the simplified tip structure.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies local quality by creating a tip with specifically controlled diameter (less than half the bar diameter) at the head portion, while the main bar maintains its full diameter. This localized dimensional control ensures that the crater entry choke diameter remains sufficiently large to prevent interference during oblique impact, while the bar itself retains its full piercing capability.

Inventive Principle:

Principle #3Local quality

2Reliability

If a tip with diameter less than half the bar diameter is used, then the crater diameter expansion is minimized preventing bar-choke interference, but the support structure must be designed to have no ballistic effects which increases design complexity

Engineering Contradiction:

Improvepiercing performance during oblique impactVSAvoidsupport structure design

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the critical parameter of tip diameter to be less than half the bar diameter, which fundamentally alters the crater formation characteristics. This parameter change ensures that the crater entry choke remains large enough to prevent bar interference during oblique impact, while the support structure parameters are adjusted to eliminate ballistic effects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The support structure is designed as a disposable component that remains attached to the tip during flight but is intended to be discarded or destroyed upon impact. This approach simplifies the overall design by eliminating the need for complex retention mechanisms, as the support structure's sole function is to hold the tip during flight and then relinquish it at impact.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Shape

If the tip diameter is reduced to less than half the bar diameter, then the choke diameter is maintained at sufficient size, but the heating-resistant material requirement adds material selection constraints

Engineering Contradiction:

Improvecrater diameterVSAvoidmaterial selection

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The invention employs composite materials by combining a heating-resistant tip material (such as tungsten alloy or ceramic) with a support structure material (such as aluminum or plastic). This composite construction allows the tip to withstand aerodynamic heating during high-speed flight while the support structure provides mechanical attachment and can be made from lighter, easier-to-manufacture materials.

Inventive Principle:

Principle #40Composite materials

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 prevents reduction in piercing performance during oblique impacts by minimizing the crater diameter expansion and allowing the bar to create a large-diameter hole without interference, maintaining effective penetration capabilities.

Implementation Method 1

the conical portion comprises a tip of a heating-resistant material

Methodology Applied

Scientific EffectAerodynamic heating: Aerodynamic Heating

Data Source

PatentUS8869704B2Sub-caliber projectile with a fitted head structure

Publication Date: 2014.10.28 NEXTER MUNITIONS SA

AI summary

An arrow-type sub-caliber projectile has a piercing bar which is cylindrical about a longitudinal axis, extended by a conical portion, and is surrounded by a sabot made of a lightweight material and allows the firing of the projectile in a weapon. This conical portion has a tip of a heating-resistant material with a maximum diameter less than half the diameter of the bar, the tip being connected to the bar by a support structure having no ballistic effects, the bar having a flat front face which is perpendicular to the longitudinal axis of the bar, the flat front face area being substantially equal to the cross-sectional area of the bar, thus with no element with ballistic effects interposed between the flat front face of the bar and the tip.