Rocket Nozzle Actuator Force Limiting Mechanism
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Solution Overview
Problem
Rocket engine nozzles experience significant lateral forces due to jet separation phenomena during start-up and shutdown phases, posing risks of engine attachment failure and potential catastrophic consequences for the launcher and launch pad.
Innovation Solution
A device comprising maneuvering assemblies with tie rods that act as rigid elements below a determined force threshold and transform into force-limiting and dissipative elements when forces exceed this threshold, using mechanisms like shear pins or pyrotechnic charges to prevent excessive force transmission and dissipate residual kinetic energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If maneuvering assemblies are used to counteract lateral forces from jet separation, then the nozzle is protected from excessive forces, but the actuators may exceed their maximum admissible force during severe separation events
Solution Approach 1:
The patent introduces a cushioning element (elastomeric material) between the actuator and the reaction structure that absorbs excess energy during severe jet separation events. This cushioning element is pre-installed in the maneuvering assembly to limit the maximum force transmitted to the actuator, preventing structural damage while maintaining normal operational effectiveness.
2Productivity
If the nozzle is designed for high altitude performance with large area ratio, then specific impulse at altitude is improved, but jet separation occurs during low altitude operation causing harmful lateral forces
Solution Approach 1:
The patent converts the harmful lateral forces from jet separation into useful work by using maneuvering assemblies that transform this energy into controlled kinetic energy for engine tilting. The system that was previously a problem (jet separation forces) becomes a potential benefit by providing additional control authority during the start-up phase when the launcher is most vulnerable.
3Reliability
If maneuvering assemblies are equipped with cushioning elements to limit force, then actuator protection is improved, but the assembly complexity increases
Solution Approach 1:
The patent uses flexible elastomeric materials as cushioning elements within the maneuvering assemblies. These flexible elements provide the necessary force limitation and energy absorption while maintaining a relatively simple structural integration. The elastomeric material can be incorporated into existing assembly geometries without requiring complex mechanical mechanisms.
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
Effectively limits forces at engine attachments, preventing breakage and enhancing the safety of the launcher and launch pad by managing and dissipating excessive energy from jet separation.
Implementation Method 1
each tie rod comprises means enabling it to act as a rigid tie rod as long as the lateral forces acting on the corresponding actuator remain below a determined force threshold and as a force-limiting element as soon as the forces acting on the actuator exceed the determined force threshold
Implementation Method 2
dissipate the residual kinetic energy
Implementation Method 3
using mechanisms like shear pins or pyrotechnic charges to prevent excessive force transmission
Implementation Method 4
pyrotechnic charges to prevent excessive force transmission
Data Source
Figure 1~2
Figure 3~4B
Figure 5~6B
AI summary
The device has a control actuator (106) e.g. electrical type actuator, with ends (106a, 106b) hinged to a rocket and an anchor structure (104). A rigid connecting rod secured to ends (102a, 102b) of a strut (102) includes a tube presenting circumferential slots. A separating unit separates the rod from the ends of the strut when lateral forces acting on the actuator exceed a determined force threshold. The separating unit enables the strut to act as an element for limiting force peaks and dissipating residual kinetic energy when the forces acting on the actuator exceed the threshold.