Ejection Seat Arm Restraint Deployment Mechanism
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Solution Overview
Problem
Current ejection seat restraint systems require mechanical attachments that divert energy from the rocket catapult, reducing clearance and performance, as they deploy after the seat has exited the aircraft, failing to effectively restrain the pilot's arms before windblast.
Innovation Solution
An arm restraint assembly with a primary arm and deployment system that includes biasing members, a reel assembly, and a fluid supply to rotate the primary arm about a pivot joint, deploying before the seat exits the aircraft, using compression and torsion springs, and a shear pin to control translation, ensuring the arms are restrained within the cockpit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical attachment (lanyard) is used to deploy restraints after seat exit, then the restraints can be deployed, but energy is taken away from the rocket catapult, reducing clearance and performance
Solution Approach 1:
The restraint system is deployed before the seat exits the aircraft through a deployment system that activates during the ejection sequence while the seat is still within the aircraft. This preliminary deployment eliminates the need for post-exit mechanical attachments, thereby preserving rocket catapult energy for propulsion and improving clearance performance.
Solution Approach 2:
The deployment system extracts the restraint deployment function from the post-exit mechanical attachment phase and relocates it to the pre-exit phase. By separating the deployment action from the seat exit moment and performing it earlier, the system eliminates energy drain on the rocket catapult while ensuring restraints are properly positioned.
2Ease of manufacture
If restraint deployment is delayed until after seat exit, then mechanical attachment can be used, but the pilot's arms are not restrained before entering the wind stream, causing potential injury
Solution Approach 1:
The restraint system is deployed in advance before the seat exits the aircraft and before the pilot enters the wind stream. The deployment system activates during the ejection sequence, ensuring that restraints are already in place to protect the pilot's arms from windblast injuries, while maintaining manufacturing simplicity through integrated deployment mechanisms.
3Device complexity
If the restraint system uses post-exit deployment, then the system can be simpler, but clearance and ejection performance are reduced due to energy loss
Solution Approach 1:
The restraint deployment system is merged with the ejection seat's existing deployment mechanisms, integrating the restraint deployment function into the overall ejection sequence. This consolidation eliminates the need for separate post-exit deployment mechanisms, maintaining system simplicity while preserving rocket catapult energy for optimal clearance performance.
Solution Approach 2:
By performing restraint deployment as a preliminary action during the ejection sequence rather than after exit, the system eliminates energy-wasting mechanical attachments while maintaining reasonable complexity through integrated design. The deployment occurs when the seat is still supported by the aircraft structure, reducing the energy burden on the rocket catapult.
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 arm restraint assembly effectively deploys before the pilot enters the wind stream, limiting rearward arm movement and enhancing ejection seat performance by maintaining energy efficiency and improving clearance.
Implementation Method 1
The first biasing member may comprise a compression spring
Implementation Method 2
The second biasing member may comprise a torsion spring
Implementation Method 3
The latch may be configured to rotate about a latch pivot joint in response to a fluid being output from the fluid supply
Data Source
AI summary
An arm restraint assembly for an ejection seat may comprise a primary arm and a primary arm deployment system operationally coupled to the primary arm. The primary arm deployment system may be configured to rotate the primary arm about a primary arm pivot joint. The primary arm deployment system may be configured to attach to the ejection seat such that the primary arm deployment system translates with the ejection seat.