Split-Tube Landing Gear Locking With Compact Pneumatic Folding
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Solution Overview
Problem
Conventional aircraft landing gear assemblies are heavy, complex, and require multiple components, leading to increased weight, maintenance needs, and potential reliability issues due to the use of numerous pin joints and additional lock links.
Innovation Solution
The introduction of a split tube spring with a longitudinal slot and a flexible vessel actuator that radially enlarges to fold, eliminating the need for conventional lock links and stays, reducing the number of components and integrating a pressurized fluid system for actuation, thereby simplifying the landing gear assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lock links and stays are used to secure the landing gear in deployed condition, then the landing gear can be reliably locked, but the assembly becomes heavy and complex with multiple components
Solution Approach 1:
The split tube spring integrates the locking function and stay support into a single component that replaces both the conventional lock link and stay. The split tube spring's bi-stable nature allows it to provide both structural support and locking capability, eliminating the need for separate lock links and reducing component count while maintaining reliability
Solution Approach 2:
The split tube spring serves multiple functions simultaneously: it acts as a stay to support the main strut, provides locking capability through its bi-stable configuration, and eliminates the need for separate lock links. This multi-functional component reduces overall system complexity while maintaining all necessary functions
2Reliability
If multiple pin joints and lock links are used in the landing gear assembly, then the locking mechanism can be achieved, but maintenance requirements increase
Solution Approach 1:
By combining the lock link and stay into a single split tube spring component, the number of separate parts that require maintenance is reduced. The integrated design eliminates multiple pin joints and connection points, simplifying the maintenance structure while preserving the locking mechanism's functionality
3Ease of operation
If conventional actuators with pin joints are used to actuate the split tube spring, then the spring can be folded for retraction, but the envelope of the landing gear assembly increases during actuation
Solution Approach 1:
A pneumatic actuator is used to provide the force needed to overcome the split tube spring's stability and initiate folding. The pneumatic system delivers high force in a compact form, enabling the actuation function without significantly increasing the assembly envelope
Solution Approach 2:
A flexible bellows component is employed to provide a compact, collapsible structure for the actuator. The bellows can expand and contract smoothly during actuation, minimizing the increase in assembly envelope while still providing the necessary mechanical advantage to fold the split tube spring
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 design results in a lighter, simpler, and more reliable landing gear assembly with fewer components, reduced maintenance requirements, and a smaller envelope, while maintaining the ability to securely lock and unlock the strut during deployment and retraction.
Implementation Method 1
a split tube spring having a longitudinal axis and a longitudinal slot, the split tube spring being biased to assume a tubular condition in which it can react axial loading thereof
Implementation Method 2
when pressuring fluid is introduced into the flexible vessel the flexible portion straightens to radially enlarge the region of the split tube spring to permit the split tube spring to assume the folded condition
Data Source
AI summary
An aircraft landing gear assembly includes a bi-stable, split line tube biased to assume a tubular condition to serve in place of a lock link or side stay and a flexible vessel actuator configured to radially enlarge the tube at a region for folding.