Skid Landing Gear Rollers for Aircraft Rebound Control

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Solution Overview

Problem

Aircraft equipped with skid landing gear often experience rebound phenomena during landing, leading to bouncing, and manual movement on the ground is difficult due to high friction, which can result in wear and ground resonance issues.

Innovation Solution

The landing gear incorporates free wheels that lock during the elastic return phase to prevent rebound and facilitate easier movement by allowing casters to rotate only in one direction, reducing friction and stabilizing the aircraft on slippery surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If skid landing gear is used for aircraft, then the structure is simple and robust, but rebound phenomenon occurs during landing causing bouncing

Engineering Contradiction:
Improvelanding stabilityVSAvoidrebound phenomenon
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A damping element is introduced as an intermediary component between the skid and the aircraft structure. This damping element absorbs the rebound energy during landing, preventing the bouncing phenomenon while maintaining the simple and robust skid structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanical properties of the landing gear system are modified by incorporating a damping element with specific energy absorption characteristics. This changes the overall stiffness and damping parameters of the landing gear, reducing rebound while maintaining structural integrity.

Inventive Principle:
Principle #35Parameter changes

2Loss of substance

If skid landing gear components have low friction coefficients, then wear is reduced, but the aircraft slips on slippery surfaces such as ship decks

Engineering Contradiction:
Improvewear of skidsVSAvoidanchoring capability
Core Design Contradiction:
Loss of substanceVSReliability

Solution Approach 1:

Different friction characteristics are applied to different components of the landing gear. The skid components have low friction coefficients to reduce wear, while the anchoring components (such as hooks or cleats) have high friction coefficients to prevent slipping on slippery surfaces like ship decks.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The landing gear system dynamically adapts its friction characteristics. During normal operation, low friction reduces wear, but when anchoring is required, the system engages components with high friction properties to prevent slipping, creating a dynamic response to operational conditions.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If conventional skid landing gear is used, then the structure is simple, but manual movement on ground is difficult due to high friction

Engineering Contradiction:
Improvestructure simplicityVSAvoidmanual movement
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The landing gear system is segmented into multiple functional components: rolling elements (wheels or rollers) for movement phases and sliding skids for stationary phases. This segmentation allows the system to use low-friction rolling contact during manual movement while maintaining the simple skid structure for landing and anchoring.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The landing gear components are designed to perform multiple functions. The same structural elements serve both as skids for landing and as supports for attached rolling elements that facilitate manual movement. This multi-functionality maintains structural simplicity while improving ease of operation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Device complexity

If skid landing gear is used, then the design is straightforward, but ground resonance phenomenon may occur

Engineering Contradiction:
Improvedesign simplicityVSAvoidground resonance resistance
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

Damping elements are incorporated into the landing gear design before ground contact occurs. These elements provide prior cushioning that absorbs vibrational energy and prevents ground resonance phenomenon, while maintaining the overall simplicity of the skid landing gear design.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The landing gear system combines different material properties and structural characteristics to resist ground resonance. The composite structure includes rigid skid components for structural integrity and flexible damping components for vibration absorption, creating a system that is both simple in design and resistant to ground resonance.

Inventive Principle:
Principle #40Composite materials

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 solution effectively reduces rebound and improves stability and maneuverability of the aircraft on the ground, minimizing wear and preventing ground resonance.

Implementation Method 1

The free wheels are configured to lock during an elastic return phase during a movement of the first skid in a first direction

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

each first free wheel being configured to lock during an elastic return phase

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

allowing casters to rotate only in one direction, reducing friction

Methodology Applied
Scientific EffectFriction reduction: Friction

Data Source

PatentEP4296159B1Skid landing gear with rollers
Publication Date: 2024.12.11 EUROCOPTER FRANCE SA
  • EP4296159B1 patent drawingFigure 1
  • EP4296159B1 patent drawingFigure 2~3
  • EP4296159B1 patent drawingFigure 4~5

AI summary

The present invention relates to a landing gear (1) equipped with at least two first wheels (36, 37) mounted on two respective first free wheels (51, 52) connected to a first skid (11) and configured during a landing phase to lock in the direction of elastic return during a movement of the first skid (11) in a first direction (401) from the first skid (11) to a second skid (12) and to be free in the direction of penetration during a movement in a second direction (402), at least two second wheels (41, 42) being mounted on two respective second free wheels (53, 54) connected to a second skid (12) and configured during a landing phase to lock during a movement of the second skid (12) in the second direction (402) and to be free during a movement in the first direction (401).