Composite Rocket Motor Cases With Swappable Propellant Cartridges
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Solution Overview
Problem
Conventional solid rocket motors (SRMs) face challenges in flexibility, efficiency, and real-time burn rate adjustments, with complex manufacturing processes and limited adaptability to different mission requirements, leading to high development costs and time.
Innovation Solution
A modular design featuring a composite case with floating, swappable propellant cartridges that allow for axial and radial expansion during ignition, utilizing a radial retention interface and gas gaps to manage thermal and mechanical stresses, enabling easy assembly and disassembly, and facilitating interchangeable components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional net cast SRMs are used with propellant cast directly into the motor casing, then the propellant adheres to the case wall forming a solid grain, but the manufacturing process is complex and time-consuming with curing taking from several days to weeks
Solution Approach 1:
The motor is divided into separate modular components: reusable motor cases and disposable propellant cartridges. The propellant is pre-cured in separate cartridges outside the motor case, eliminating the need for on-site curing. This segmentation allows parallel manufacturing of cases and cartridges, dramatically reducing total production time and simplifying the manufacturing process.
Solution Approach 2:
The propellant is pre-cured in the cartridges before assembly with the motor case. This preliminary curing action eliminates the lengthy curing step from the motor assembly process, allowing cartridges to be manufactured and stored separately, then quickly assembled into the motor case when needed.
2Adaptability or versatility
If conventional SRMs are designed for specific missions, then the thrust profile is optimized for that mission, but the development costs and time are high with limited adaptability
Solution Approach 1:
The motor system is segmented into reusable motor cases and interchangeable disposable cartridges. Each cartridge can be designed with different propellant formulations, grain geometries, and burn rates optimized for specific mission requirements. This allows rapid reconfiguration for different missions by simply swapping cartridges rather than redesigning entire motor systems.
Solution Approach 2:
The motor case is designed as a universal platform that can accommodate multiple types of cartridges with different thrust profiles and performance characteristics. This multi-functionality allows a single motor case design to serve multiple mission requirements by simply changing the cartridge, reducing development complexity and costs.
3Adaptability or versatility
If the propellant is cast directly into the motor casing, then the grain forms adhering to the case wall, but flexibility for real-time burn rate adjustments is limited
Solution Approach 1:
The propellant system is segmented into replaceable cartridges that can be swapped based on required burn rates and thrust profiles. This allows real-time adjustment of burn rate characteristics by selecting different cartridges with appropriate propellant compositions and grain geometries, without modifying the motor case or ignition system.
Solution Approach 2:
The system transitions from a static, fixed-propellant design to a dynamic, interchangeable cartridge system. Different cartridges can be selected and installed based on real-time mission requirements, enabling flexible adjustment of burn rates and thrust profiles without redesigning the entire motor 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 design reduces complexity and cost, enhances flexibility and efficiency, allows for real-time ground testing, and supports adaptable thrust profiles, while reducing waste and environmental impact through reusable components and efficient inventory management.
Implementation Method 1
a composite case with floating, swappable propellant cartridges that allow for axial and radial expansion during ignition
Implementation Method 2
utilizing a radial retention interface and gas gaps to manage thermal and mechanical stresses
Implementation Method 3
The propellant ingredients, including the oxidizer, fuel, binder, and any additives, are mixed together in a specific ratio to achieve the desired combustion characteristics
Data Source
AI summary
The present invention is a system and method for manufacturing a modular motor architecture, comprising a rocket motor comprising an extended case with a forward end and an aft end. The forward end features a radial retention interface with a multi-stack polar boss, a multi-stack forward polar boss enclosure, and radial tabs. The multi-stack polar boss is molded using boss molding material into three to twenty radial tabs and is wound into the composite case. The motor includes multiple multi-stack cartridges that house propellant and a central combustion chamber. These cartridges, including a forward cartridge, a primary cartridge, and an aft cartridge, are suspended inside the case and secured co-axially with the composite case by various joints, including polar and aft joints. The aft cartridge is located at the aft end, which features a closure and a nozzle.