Shear Wire Adaptor Kit for Military Aircraft Ejection
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Solution Overview
Problem
Existing shear wire systems for arming stores during ejection from military aircraft face issues with jamming and inconsistent tension due to varying angles and forces, leading to potential arming or jettisoning errors, especially when dealing with stores having single fuze units and twin arming units.
Innovation Solution
The use of a calibrated arming apparatus with breakable links and flexible drop links that apply tension evenly to the fuze unit, ensuring reliable operation by adjusting the angle and force distribution to prevent jamming and ensure proper arming or jettisoning, even when dealing with non-compatible ERU and store configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shear wires are used to arm stores during ejection, then the store can be armed as it leaves the aircraft, but the shear wires may jam in the AU due to large angles between them and the AU receptacles, leading to unreliable operation
Solution Approach 1:
A pulley system is introduced as an intermediary mechanism between the shear wire and the fuze unit. The pulley guides the shear wire through a controlled path, ensuring it pulls the fuze door open at the correct angle while preventing jamming in the AU receptacle. The pulley acts as a mediator that transforms the force application geometry.
Solution Approach 2:
The solution moves the problem from a single-dimension linear pull to a multi-dimensional spatial arrangement. By positioning pulleys at specific locations and routing the shear wire through them, the system creates a three-dimensional force application path that optimizes the pull angle on the fuze door while maintaining clearance from the AU receptacle.
2Reliability
If shear wires are attached at extreme angles to the FZU door bail, then the FZU door may be torn off, but using standard attachment methods results in uneven tension and unpredictable shear wire breaking
Solution Approach 1:
Pulleys are introduced as intermediary elements between the shear wire and the FZU door bail. These pulleys distribute the tensile load evenly and control the angle of force application, preventing both uneven tension that causes unpredictable wire breaking and extreme angles that could tear off the door.
Solution Approach 2:
The system changes the geometric parameters of force application by using pulleys to optimize the angle and distribution of tension. This ensures the shear wire pulls at an optimal angle that is neither too shallow (causing jamming) nor too extreme (causing door damage), while maintaining even tension distribution.
3Adaptability or versatility
If a single FZU-equipped store is mounted on ERUs with twin AUs, then the store can be carried, but the large and unpredictable angle between shear wire and attachment bail leads to uneven tension and potential failure to arm
Solution Approach 1:
The pulley system is designed to be universally applicable to both single-AU and twin-AU configurations. The same basic mechanism works regardless of whether the store is mounted on a single AU or twin AUs, providing consistent and reliable arming function across different ERU configurations without requiring configuration-specific 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 apparatus ensures reliable arming or jettisoning of stores by maintaining equal tension and angle on the fuze unit actuation lanyard, preventing jamming and ensuring the store is ejected in the intended armed or unarmed state, reducing the risk of damage to the fuze unit.
Implementation Method 1
each wire containing a shearable link designed to break at a predetermined tensile load
Implementation Method 2
A spring-loaded ball detent prevents the anchoring eye from falling out of the receptacle under gravity/g-force/vibration
Implementation Method 3
The pistons are typically gas-powered, with the gas supplied from a pair of pyrotechnic cartridges
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Arming apparatus is installable between twin arming units (101, 102) of an ejector release unit in a military aircraft, and a single fuzing unit (74) of a store (78). The arming apparatus comprises sequentially breakable links (221, 222, 223) which ensure reliable ejection of the store in an armed state, or jettisoning of the store in an unarmed state, as desired.