Aircraft Strap Feeder Unit with Unfixed Default Mode
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Solution Overview
Problem
Aircraft restraint systems face challenges in balancing occupant safety with comfort and mobility, as existing systems either provide limited head motion or are uncomfortable and cumbersome, and current solutions to meet head injury criteria add cost and weight to the aircraft.
Innovation Solution
A modal restraint system with a strap feeder unit that switches between unfixed and fixed modes in response to mechanical failure detection, allowing for enhanced occupant security during life-threatening events while maintaining comfort and mobility during normal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed seatbelts are used to provide short HIC trajectory and meet head injury criteria, then head injury protection is improved, but occupant comfort and mobility deteriorate
Solution Approach 1:
The restraint system dynamically switches between fixed and unfixed modes based on flight conditions. During normal operations, the system remains unfixed to allow occupant mobility and comfort. When a precautionary event is detected (such as turbulence or mechanical failure), the system automatically transitions to fixed mode to provide rigid restraint and meet HIC requirements, thus resolving the contradiction between comfort and safety
2Ease of operation
If inertia reel seatbelts are used to increase occupant comfort and mobility, then ease of operation is improved, but head injury protection deteriorates due to delayed reaction time
Solution Approach 1:
The system performs preliminary action by detecting precautionary events (such as mechanical failures or turbulence) before they escalate into dangerous conditions. Upon detection, the system proactively transitions from unfixed to fixed mode, locking the occupant into a secured position in advance of any potential impact or hazardous event, thereby eliminating the delayed reaction time inherent in traditional inertia reel systems
3Reliability
If head clearance and soft impact surfaces are provided to meet HIC requirements, then head injury protection is improved, but aircraft cost and weight increase
Solution Approach 1:
The system changes the operational parameters of the restraint system based on flight conditions. Rather than providing continuous fixed restraint or adding physical protective structures, the system dynamically adjusts the restraint state (fixed vs. unfixed) in response to detected precautionary events, meeting HIC requirements only when necessary and thereby avoiding the added weight and cost of permanent structural modifications
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 system effectively reduces occupant movement during hazardous events, enhancing safety while allowing for greater freedom of movement in normal conditions, thus addressing the limitations of existing seatbelt systems.
Implementation Method 1
The precautionary event includes detection of an aircraft mechanical failure by the mechanical failure sensor
Data Source
AI summary
A modal restraint system for an occupant of a seat of an aircraft. The modal restraint system includes a strap feeder unit and a strap selectively retractable into and extendable from the strap feeder unit. The strap feeder unit is adapted to switch between a plurality of modes including an unfixed mode and a fixed mode. The strap is extendable from and retractable into the strap feeder unit in the unfixed mode. The strap is substantially unextendable from the strap feeder unit in the fixed mode. The strap feeder unit is in the unfixed mode by default. The strap feeder unit is operable to switch from the unfixed mode to the fixed mode in response to a precautionary event including detection of an operational parameter that is beyond a predetermined threshold, thereby reducing freedom of movement of the occupant relative to the seat.