Metal-Stabilized Propellant Grain for Gun-Fired Rocket Motor
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Solution Overview
Problem
Conventional gun-fired rocket motors face issues with stress and strain due to inertia during launch, leading to potential fracture and unplanned burning, as well as damage from gun dynamic pressure and propellant particles, which can result in motor failure, and existing solutions complicate manufacturing with separate ignition systems.
Innovation Solution
A rocket motor design that integrates a rigid structure into the burnable propellant grain to stabilize it during acceleration and incorporates a baffled end cap to prevent propellant particles from entering the nozzle, reducing strain and protecting the motor from pressure shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a semi-rigid propellant material is used in the rocket motor, then the propellant can be flexibly formed, but the propellant moves toward the aft end during gun acceleration causing stress and strain that leads to fracture and unplanned burning
Solution Approach 1:
The patent combines a semi-rigid propellant material with a rigid structure (such as a mandrel or support framework) to create a composite propellant grain assembly. The rigid structure provides mechanical stability during gun acceleration while the semi-rigid propellant maintains its flexible formability. This composite approach resolves the contradiction by integrating materials with complementary properties.
2Object-affected harmful factors
If blast tubes or closed caps are used to protect the rocket motor from gun dynamic pressure, then the rocket motor is protected from damaging shock, but a separate motor ignition device is required making manufacturing more complex and costly
Solution Approach 1:
The patent integrates the protective function (blast tube or cap) and the ignition function into a single unified structure. The rigid structure that protects the propellant grain also serves as the ignition conduit, allowing gun gases to pass through and ignite the propellant without requiring a separate ignition device. This merging eliminates the need for additional ignition components while maintaining protection from dynamic pressure.
3Reliability
If the rigid structure is retained during burning, then the structure provides continuous stabilization, but the structure must be formed of durable metal with high melting point increasing manufacturing complexity
Solution Approach 1:
The patent changes the material parameters of the rigid structure by using propellant-compatible materials (such as binder materials or low-melting-point metals) that can be easily manufactured and integrated with the propellant grain. These materials are selected to have burn rates similar to the propellant, allowing the structure to be consumed along with the propellant rather than requiring durable high-melting-point metals.
4Ease of manufacture
If the rigid structure is ablated during burning, then the structure is consumed with the propellant, but the structure must have burn rate similar to propellant grain requiring precise material selection
Solution Approach 1:
The patent uses materials for the rigid structure that have homogeneous or matched burn characteristics with the propellant grain. This is achieved by using binder materials or propellant compositions that ensure uniform consumption rates, eliminating the need for complex burn rate matching while maintaining ease of manufacture.
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 integrated rigid structure and baffled end cap effectively stabilize the propellant grain and prevent damage from gun dynamic pressure, enhancing the reliability and performance of the rocket motor by reducing the risk of fracture and failure, while simplifying manufacturing by eliminating the need for separate ignition systems.
Implementation Method 1
the semi-rigid material of the burnable propellant may move toward an aft end of the projectile and the attached rocket motor due to the inertia caused by the projectile and rocket motor moving forward through the gun
Implementation Method 2
The end cap defines a baffled path through the end cap to dampen gas flow into the nozzle and prevent particles of the gun propellant from entering the rocket motor
Implementation Method 3
The burnable propellant grain of the rocket motor may be ignited by the gas generated during burning of the gun propellant
Data Source
AI summary
A rocket motor for a gun-fired projectile is configured stiffen the burnable propellant in the rocket motor during burning and/or protect the rocket motor from the pressure that occurs during firing of the projectile from the gun. The rocket motor may include a rigid structure that is integrated into the burnable propellant grain to stabilize the burnable propellant grain during burning of the burnable propellant grain. The rigid structure has a matrix or truss-like shape that extends into the depth of the burnable propellant grain. The rocket motor may include a baffled end cap that covers a nozzle of the rocket motor. The end cap defines a baffled path through the end cap to dampen gas flow into the nozzle and prevent particles of the gun propellant from entering the rocket motor. A rocket motor may implement the rigid structure or the baffled end cap, or both structures.