External Load Damper for Variable-Length Landing Gear
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Solution Overview
Problem
The pitch rotation of an airplane is limited by the length of the shock strut, which restricts the angle of attack during take-off, potentially leading to tail-strike issues.
Innovation Solution
An external articulating load damper is introduced, passively causing a lever to rotate with respect to the strut piston, extending the landing gear and increasing its length when the extension force exceeds the ground force, allowing greater pitch rotation and incorporating a linkage system for enhanced movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the shock strut length is increased to achieve greater angle of attack during take-off, then the pitch rotation capability is improved, but the structural complexity and weight of the landing gear increase
Solution Approach 1:
The patent applies dynamics by making the landing gear length variable rather than fixed. The load damper dynamically adjusts the effective length of the landing gear arrangement during operation, allowing the system to adapt between a shorter configuration for ground operations and an extended configuration for take-off pitch rotation, thereby avoiding the permanent complexity of a longer fixed structure
Solution Approach 2:
The load damper is externally coupled to the shock strut, creating a nested arrangement where the load damper extends the functional length of the shock strut only when needed. This nested configuration allows the extended length capability without permanently increasing the base structure's complexity or weight
2Reliability
If the shock strut length is increased to prevent tail-strike during take-off, then the safety is improved, but the weight of the landing gear increases
Solution Approach 1:
The system dynamically extends the landing gear length only during the critical take-off phase when pitch rotation is needed for tail-strike prevention. During other phases, the landing gear maintains a shorter, lighter effective configuration, thus achieving safety without the penalty of permanent weight increase
Solution Approach 2:
The load damper is passively actuated by the extension force generated during take-off rotation, automatically extending the landing gear length when needed without requiring additional active control systems, motors, or complex actuation mechanisms that would increase weight
3Ease of operation
If an external load damper is added to extend the landing gear for greater pitch rotation, then the angle of attack capability is improved, but the device complexity increases
Solution Approach 1:
The load damper operates passively, automatically extending or retracting based on the extension force applied during take-off or ground operations. This passive operation eliminates the need for complex active control systems, sensors, or actuators, thereby improving angle of attack capability without proportionally increasing control complexity
Solution Approach 2:
The load damper acts as an intermediary element between the shock strut and the lever, providing the extension function without requiring direct modification of the core shock strut structure. This intermediary approach allows the system to gain extended capability while keeping the base structure relatively simple
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
This solution enables increased airplane pitch rotation during take-off, prevents tail-strike, and provides ground force damping while minimizing part count, reducing weight, and enhancing the robustness of the landing gear arrangement.
Implementation Method 1
the load damper is configured to increase a length of the landing gear arrangement in response to an extension force of the load damper increasing above a ground force reacted through the landing gear arrangement
Implementation Method 2
The load damper may further dampen ground forces during take-off and/or landing
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A landing gear arrangement may comprise a lever (230) configured to be coupled between an axle and a strut piston of a shock strut (201), a load damper (250, 450) configured to be externally coupled between the shock strut (201) and the lever (230), wherein the load damper (250, 450) is configured to increase a length of the landing gear arrangement in response to an extension force of the load damper increasing above a ground force reacted through the landing gear arrangement. The load damper (250, 450) may be located externally from the strut piston.