Ejection Seat Head Retention and Arm Curtains
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Solution Overview
Problem
Ejection seats pose risks to pilots due to windblast forces causing misalignment and limb flailing during ejection, potentially leading to injury, especially when occupants are not in an optimal position or incapacitated.
Innovation Solution
The ejection seat incorporates stowable head support beams and arm retention curtains that deploy to maintain the occupant's head and arms in position, using tethers and snubbers to secure the curtains around the pilot, with inflatable head support beams and flexible, mesh arm retention curtains to minimize flailing and snagging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ejection seat uses a simple seat structure without additional retention mechanisms, then the device complexity is low, but the occupant's head and limbs can flail around in the windblast, risking injury
Solution Approach 1:
The arm retention curtains are pre-positioned and stowed in a compact configuration within the seat structure before ejection. Upon deployment, they automatically unfold and position themselves to retain the occupant's arms, preventing flailing without requiring complex active control systems
Solution Approach 2:
The arm retention curtains are made from flexible fabric material that can conform to the occupant's body shape while providing retention. The flexible nature allows the curtains to adapt to different occupant sizes and positions, effectively containing limbs during ejection without rigid mechanical structures
2Stability of the object's composition
If the ejection seat includes head support beams and arm retention curtains, then the occupant position is maintained, but the device complexity increases
Solution Approach 1:
The head support beams and arm retention curtains are integrated into a unified ejection seat system where the curtains are attached to the seat structure and headrest assembly. This merging of functions into a single coordinated system provides comprehensive occupant retention without requiring separate independent mechanisms
Solution Approach 2:
The arm retention curtains transition from a stowed compact state to a deployed extended state during ejection. This dynamic configuration allows the system to provide retention only when needed during the ejection sequence, reducing complexity compared to permanently extended retention structures
3Object-affected harmful factors
If the arm retention curtains are kept extended, then the arms are retained, but the curtains may snag on equipment in the cockpit during ejection
Solution Approach 1:
The arm retention curtains are pre-stowed in a compact retracted configuration within the seat structure before ejection initiates. This preliminary stowing prevents any contact with cockpit equipment during the critical initial phase of ejection when the seat is moving through the windblast
Solution Approach 2:
The curtains dynamically transition from a retracted non-intrusive state to an extended retention state only when needed. This dynamic behavior eliminates the snagging hazard associated with permanently extended curtains while maintaining the arm retention function during ejection
4Stability of the object's composition
If the ejection seat includes stowable head support beams that deploy forwardly, then the head is captured, but the device complexity increases
Solution Approach 1:
The head support function is segmented into discrete deployable beams that can be individually activated. These segmented beams provide focused support to the head region without requiring a complex full-headrest structure, reducing overall system complexity while maintaining head position stability
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 solution effectively maintains the occupant in an optimal position throughout the ejection process, reducing the risk of injury from windblast forces and ensuring a stable ejection path by securely retaining the head and arms, thereby enhancing safety.
Implementation Method 1
inflatable head support beams
Implementation Method 2
a fourth corner is secured to a respective tether which is operable to draw the fourth corner forwards from the seat back
Implementation Method 3
a rocket motor or other propulsion system causes the seat to be propelled upwardly out of the cockpit
Implementation Method 4
A parachute subsequently deploys and the ejection seat and its occupant return to the ground
Data Source
AI summary
An ejection seat is disclosed comprising a seat back; a headrest assembly mounted to or forming part of the seat back; a pair of head support beams stowable in the headrest assembly, configured to be deployed such that they project forwardly from the headrest assembly, for capturing a seat occupant's head therebetween, and a pair of arm retention curtains, wherein at least part of each arm retention curtain is stowed in a rolled condition, configured such that deploying the head support beams and/or drawing the tethers forward from the seat back unfurls the arm retention curtains.