Elastically Deformable Landing Gear Pin Cap
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Solution Overview
Problem
Current aircraft landing gear pin caps are often incompatible with the design of the pins, difficult to fit, and can be impossible to refit once removed, leading to aerodynamic noise issues due to hollow pins causing air column resonances.
Innovation Solution
A self-contained cap with a base, head, and body portions made from elastically deformable material, secured by a bolt with a threaded portion, allowing the cap to radially expand and engage with the pin's inner surface for noise reduction, ease of use, and prevention of over-tightening, featuring a non-metallic contact surface and distinct coloration for correct insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a cap is fitted over a hollow structural pin to reduce aerodynamic noise, then noise reduction is achieved, but the cap becomes difficult to fit and refit
Solution Approach 1:
The cap utilizes elastic deformation of its body portion to change its dimensional parameters dynamically. During installation, the body portion is compressed radially to reduce its outer diameter, allowing it to pass over the pin. Upon release, the elastic material returns to its original shape, creating a friction fit that secures the cap without requiring permanent deformation or complex fastening mechanisms.
Solution Approach 2:
The cap transitions from a rigid, fixed-dimension component to a dynamic component that can change its dimensions through elastic deformation. This dynamic behavior allows the cap to adapt its size during installation and removal operations, making the process reversible and repeatable multiple times without damage.
2Object-affected harmful factors
If the cap is secured tightly to the pin to ensure noise reduction, then noise reduction effectiveness increases, but the pin may be damaged due to over-tightening
Solution Approach 1:
The elastic body portion changes its radial dimension under compression, allowing it to expand outward and engage with the pin bore wall. This elastic expansion creates a secure friction fit that reduces noise while inherently limiting the maximum pressure applied to the pin, preventing damage through material elasticity.
Solution Approach 2:
The elastic material acts as a cushioning element between the cap and the pin. When the cap is installed, the elastic body portion absorbs and distributes the contact pressure, preventing concentrated loads that could damage the pin. This cushioning effect is built into the design from the beginning, protecting the pin during installation and operation.
3Adaptability or versatility
If the cap design is made universal to fit different pin types, then adaptability increases, but the fit precision decreases
Solution Approach 1:
The cap is designed with a universal interface that can accommodate various pin types and bore configurations. The elastic body portion and engagement features are configured to work with different pin geometries, allowing a single cap design to serve multiple applications across different landing gear assemblies.
Solution Approach 2:
The elastic material allows the cap to adapt its dimensional parameters to match different pin bore sizes and tolerances. This elasticity compensates for variations in manufacturing tolerances and pin dimensions, maintaining precise fit quality across different pin types without requiring custom-designed caps for each variant.
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 cap effectively reduces aerospace noise, is reusable, and prevents damage to the pin by controlling radial movement and pressure, ensuring a consistent fit and long pin lifetime while avoiding environmental hazards from coatings.
Implementation Method 1
The body being formed of an elastically deformable material such that upon tightening of the bolt, the base portion moves towards the head portion and the elastically deformable material moves radially outwards
Data Source
AI summary
An aircraft landing gear assembly comprising: a structural pin defining a first bore having a longitudinal insertion axis; a cap for covering the bore, the cap comprising: a base portion; a head portion; a body portion positioned between the base portion and the head portion; and a bolt which extends between the head portion and the base portion and comprises a threaded portion so that engagement of either the head portion or the base portion with the threaded portion moves either the head portion or the base portion relative to the other, the body being formed of an elastically deformable material such that upon tightening of the bolt, the base portion moves towards the head portion and the elastically deformable material moves radially outwards such that a contact surface of the elastically deformable material engages with an inner surface of the first bore in order to retain the cap.