Mechanical Thrust Termination Device for Solid Rocket Motors
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Solution Overview
Problem
Conventional thrust termination devices in solid rocket motors, such as pyrotechnic devices, generate significant impacts and fragment dispersion during operation, affecting the stability and precision of missile flight due to substantial pressure and temperature conditions, making it difficult to control thrust termination effectively.
Innovation Solution
A thrust termination device with a mechanical structure that includes a closure, snap ring, wedge, and pulling wire mechanism to abruptly open thrust termination ports at the combustion chamber dome, ensuring air-tightness and structural stability under high pressure and temperature, and allowing controlled stage separation by extracting the wedge and expelling the snap ring and closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnic devices are used for thrust termination, then thrust termination can be achieved, but significant impacts and fragment dispersion occur affecting flight stability
Solution Approach 1:
The patent replaces the pyrotechnic (chemical) system with a mechanical system consisting of a closure, snap ring, wedge, and pulling wire. This mechanical substitution eliminates the harmful effects of explosion-generated fragments and uncontrolled impacts while maintaining the thrust termination function through controlled mechanical opening of the combustion chamber.
Solution Approach 2:
The patent introduces a wedge as an intermediary element between the pulling wire and the snap ring closure. The wedge converts the linear pulling force into radial expansion force that reliably opens the closure, providing controlled and smooth thrust termination without the harmful impulsive effects of direct pyrotechnic actuation.
2Productivity
If thrust termination ports are opened abruptly, then thrust termination is achieved, but combustion pressure causes structural stress
Solution Approach 1:
The closure, snap ring, and wedge assembly is pre-positioned and pre-loaded during combustion to withstand the high combustion pressure. The structure is designed to maintain structural integrity under pressure until the pulling wire is activated, at which point the pre-positioned mechanism rapidly opens the ports for thrust termination.
Solution Approach 2:
The thrust termination mechanism is divided into separable components (closure, snap ring, wedge, pulling wire) that can be independently designed and positioned. This segmentation allows each component to be optimized for its specific function while collectively maintaining structural stability under combustion pressure and enabling rapid opening when needed.
Data Source
AI summary
Disclosed is an abrupt opening apparatus of a pressurized chamber in an intended procedure to accomplish thrust termination for a stage separation of the solid rocket motor. It can open trust termination ports with simple mechanical structure to thereby terminate the normal thrust of a nozzle reliably, if it is intended to terminate the normal thrust produced from the nozzle of the rocket motor to thereby impede the forward movement of the rocket motor by producing the reverse thrust. The thrust termination device for the rocket motor comprises a closure 210 for closing the thrust termination ports in an air-tight structure; a snap ring 220 for supporting the closure 210; a wedge 230 arranged between both free ends of the snap ring; a wedge fixing plate 240 for fixing the wedge; and, a pulling wire 250 linked to the wedge at one end thereof for extracting the wedge by being drawn when the thrust termination is performed.