Inert Projectile Submunitions Dispensing via Aerodynamic Fracture
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Solution Overview
Problem
Conventional gun-launched projectiles for naval defense against small boat threats are limited by fuzing safe and arm devices that preclude their use at close ranges, rendering them ineffective against proximate threats.
Innovation Solution
Development of an inert axisymmetric projectile with a sabot housing, submunitions package, and slip obturator that disperses submunitions upon launch by employing aerodynamic pressure and rotational forces to fracture and unfurl the sabot petals, releasing the payload for targeted engagement without the need for energetic materials or conventional fuzes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fuzing safe and arm devices are used in 5-inch diameter projectiles, then reliable target engagement is achieved, but close-range engagement capability is lost
Solution Approach 1:
The patent removes the conventional fuzing safe and arm devices from the projectile system. Instead of using traditional explosive fuzes with complex safety mechanisms, the invention extracts this function entirely and replaces it with an inert dispersal mechanism that relies on aerodynamic forces and centrifugal effects to distribute submunitions, thereby enabling close-range engagement without the constraints of conventional fuzing safety distances
Solution Approach 2:
The patent replaces the mechanical fuzing system with an aerodynamic and inertial dispersal mechanism. The submunitions are released through the interaction of aerodynamic pressure, rotational forces, and structural fracture of the sabot housing, eliminating the need for mechanical fuzes and their associated safety constraints
2Volume of moving object
If sabot petals are used to contain submunitions package, then compact projectile structure is achieved, but structural integrity under gun launch loading is compromised
Solution Approach 1:
The sabot housing is divided into multiple petals that can be restrained during launch and then separated to dispense submunitions. This segmentation allows the structure to maintain integrity under launch loading while enabling effective dispersal at the target, as each petal can be independently constrained and then released
Solution Approach 2:
The sabot petals are designed with dynamic characteristics that allow them to transition from a constrained state during launch to an unfurled state during flight. The petals incorporate features that enable controlled deformation and fracture under specific aerodynamic and centrifugal loads, transforming the structural integrity requirement from static to dynamic
3Stability of the object's composition
If barrel rifling is used to stabilize projectile flight, then flight stability is improved, but spin-induced payload spread is increased
Solution Approach 1:
The slip obturator serves as an intermediary element between the rifled barrel and the projectile body. It engages with the rifling grooves to provide stabilization during flight while allowing the projectile to 'slip' at the interface, reducing the transfer of rotational spin to the payload and thereby minimizing spin-induced spread
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 self-defense capabilities of naval vessels by enabling effective engagement of close-range, asymmetric surface threats with a near-field projectile that disperses a payload over an extended area, reducing spin-induced spread and maintaining accuracy through controlled fracture mechanisms.
Implementation Method 1
The slip obturator engages the lands and grooves of the barrel rifling and seals the explosive gases behind the projectile, preventing them from advancing further up the projectile
Implementation Method 2
The projectile 'slips' at the interface between the slip obturator and the base plug, reducing the spin on the projectile that would have otherwise been induced by the barrel rifling
Implementation Method 3
Upon launch the ring fractures from aerodynamic pressure and rotational forces
Implementation Method 4
The band suffers a controlled fracture by means of stress concentrations at geometric cross-section reductions along its circumference due to the combined loadings of axial inertial setback, rotational inertia, and aerodynamic stagnation pressure
Implementation Method 5
The submunitions immediately begin to disperse radially due to their rotational inertia and their interaction with the ambient air
Data Source
AI summary
An inert axisymmetric projectile is provided for launching from a shipboard gun and dispersing submunitions at a target. The projectile includes a base plug, a sabot housing, a submunitions package, and a retainer ring. The sabot housing includes a plurality of sabot petals angularly arranged and attached to the plug. The housing includes a payload portion and a nose portion, with a passage corridor between these portions. The submunitions package is contained within the payload portion and constrained radially by the housing. The retainer ring constrains the petals for joining together. Upon launch aerodynamic pressure fractures the ring and causes the petals to unfurl, thereby releasing the submunitions package for dispersal.