Rotorcraft Skid Landing Gear Roll Damping via Crank Linkage
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Solution Overview
Problem
Conventional rotorcraft skid landing gear struggles to effectively dampen roll-induced vibrations, leading to the ground resonance phenomenon, which can cause instability and overturning, especially when resonant frequencies align, and modifying stiffness is challenging without impacting vertical stiffness or increasing structural loads.
Innovation Solution
The landing gear incorporates a damper device with stroke-transfer means hinged to the fuselage and cross-members, featuring cranks and link rods that transmit fuselage movements to the damper, providing targeted damping in roll modes without affecting vertical or pitching movements, thus minimizing ground resonance risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stiffness of landing gear is increased to reduce roll vibrations, then ground resonance risk decreases, but vertical stiffness increases causing harsher landings and increased structural loads
Solution Approach 1:
The landing gear system is segmented into vertical support function (skids and cross-members) and roll damping function (separate damper device). This allows independent optimization of vertical stiffness and roll damping characteristics without compromising either function.
Solution Approach 2:
A dedicated damper device acts as an intermediary element between the cross-member and fuselage, specifically targeting roll vibrations. This intermediary component provides roll damping without affecting the vertical stiffness of the main landing gear structure.
2Reliability
If damper is added to reduce roll vibrations, then ground resonance is reduced, but device complexity increases
Solution Approach 1:
The damper device is integrated with existing landing gear components (cross-members and fuselage attachment points), allowing it to serve multiple functions: roll damping, structural reinforcement, and compatibility with existing gear configurations. This multi-functionality reduces overall system complexity despite adding damping capability.
Solution Approach 2:
The damper introduces dynamic roll damping capability to the otherwise static landing gear structure. The stroke-transfer means with cranks and link rods convert fuselage roll movements into damper stroke, enabling active vibration control without permanently altering the static structural configuration.
3Reliability
If stroke-transfer means with cranks and link rods is used to transmit movements, then targeted roll damping is achieved, but manufacturing complexity increases
Solution Approach 1:
The stroke-transfer means is segmented into discrete components (cranks, link rods, hinges) that can be manufactured separately using standard fabrication processes and then assembled. This modular approach simplifies manufacturing compared to creating a monolithic complex mechanism.
Solution Approach 2:
The crank components utilize curved geometries that can be efficiently manufactured using conventional machining or forming processes. The curved paths naturally guide the motion transmission while maintaining simplicity in the manufacturing methodology.
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 effectively dampens roll vibrations, reducing the risk of ground resonance while maintaining aircraft stability and comfort, and can be adapted to existing aircraft without significant structural modifications.
Implementation Method 1
at least one damper hinged to the second hinge of the first stroke-transfer means and to the second hinge of the second stroke-transfer means
Data Source
AI summary
The invention relates to landing gear of an aircraft, the landing gear having skids and cross-members. The landing gear has at least one damper device arranged on at least one of the cross-members referred to as a “damped” cross-member. The damper device includes two stroke-transfer means hinged to the damped cross-member and to a fuselage of the aircraft. Each stroke-transfer means comprises a crank hinged to the damped cross-member and a link rod hinged to the crank and to the fuselage. A damper is hinged to each crank.