Detachable Drag Arm for Aircraft Landing Gear Weight Reduction
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Solution Overview
Problem
Main landing gear assemblies for commercial aircraft face challenges due to high weight, complex geometry, and significant noise generation, primarily because of the complex design and material usage in the main fittings, which increases manufacturing costs and contributes to aerodynamic inefficiencies.
Innovation Solution
The main fitting design includes a detachable drag arm pivotally coupled to the main barrel and cross beam, limiting loads to tensile and compressive forces, allowing for a simpler, lighter, and more aerodynamic structure that can be manufactured using alternative materials and processes, such as additive manufacturing, and featuring an aerodynamic profile to reduce drag and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the main fitting is made of high alloy steels with complex geometry to withstand high loads, then the strength and reliability are improved, but the weight and manufacturing cost increase significantly
Solution Approach 1:
The main fitting is divided into separate components: the main barrel and the drag arm are manufactured independently and then assembled together. This segmentation allows each component to be optimized separately, enabling the use of lighter materials and simpler manufacturing processes while maintaining the overall structural strength required to withstand high loads during landing gear operation
Solution Approach 2:
The patent employs different materials for different components of the main fitting. The main barrel may use traditional high-strength materials to handle the primary loading, while the drag arm can use lighter materials since it primarily experiences axial loads. This composite material approach reduces overall weight while maintaining sufficient strength through strategic material placement
2Device complexity
If the drag arm is integrally formed with the main barrel to simplify assembly, then the device complexity is reduced, but the manufacturing complexity and weight increase
Solution Approach 1:
The drag arm is designed as a separate component that can be manufactured independently from the main barrel using simpler processes such as additive manufacturing or conventional machining. This segmentation reduces the manufacturing complexity of each individual part while the standardized connection interface ensures simple assembly, effectively resolving the contradiction between assembly simplicity and manufacturing ease
Solution Approach 2:
The drag arm is extracted as a separate, removable component from the integral structure. This allows the drag arm to be manufactured using optimized processes for its specific function (primarily axial loading), and enables easier maintenance and replacement without requiring complex manufacturing of the entire assembled unit
3Strength
If the main fitting has complex geometry to support high loads, then the strength is improved, but the aerodynamic efficiency deteriorates due to increased drag and noise
Solution Approach 1:
By separating the drag arm from the main barrel, each component can be independently optimized for its primary function. The main barrel maintains the necessary complex geometry for strength, while the detached drag arm can be designed with streamlined contours that reduce aerodynamic drag and noise, as it no longer needs to integrate structurally with the main barrel
Solution Approach 2:
The drag arm, being a discrete component exposed to airflow, can be given a specific aerodynamic profile tailored to its location and function. This local optimization of geometry improves airflow characteristics around the landing gear assembly without compromising the overall structural integrity provided by the main barrel
4Reliability
If the drag arm is designed to handle non-axial loads and bending, then the reliability is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The drag arm is extracted as a separate component with a simplified structure optimized for axial loading only. By removing the requirement for the drag arm to handle non-axial loads and bending moments, the structural complexity is significantly reduced. The connection between the drag arm and main barrel is designed to properly transmit loads, ensuring that the simplified drag arm structure maintains sufficient reliability for its primary function
Data Source
AI summary
An aircraft landing gear assembly includes a main fitting comprising having a main barrel and a cross beam fixedly positioned relative to the main barrel and extending radially from the main barrel. The main fitting further includes a drag arm with a first end pivotally coupled to the cross beam by a first pivotal connection and a second end pivotally coupled to the main barrel by a second pivotal connection.