Split Pivot Fitting for Helicopter Landing Gear Resonance
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Solution Overview
Problem
Existing skid-type aircraft landing gear systems require heavy and expensive rocker beams to prevent resonance, which add drag and complexity, and pivot bolts need accessible paths through the fuselage for maintenance, increasing weight and design complexity.
Innovation Solution
A split pivot fitting system that replaces pivot bolts, comprising a forward fitting, aft fitting, lower strap, and sleeve assembly, allowing for easy access and installation, and enabling selected longitudinal rocking of the aircraft without rocker beams, by being pivotally coupled to cross beams and keel beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rocker beams are used to prevent resonance, then aircraft stability is improved, but weight and device complexity increase
Solution Approach 1:
The invention divides the landing gear structure into modular components: forward cross tube, aft cross tube, keel beams, and pivot fittings. This segmentation eliminates the need for a single complex rocker beam while maintaining the required stability function through distributed pivot points.
Solution Approach 2:
The invention extracts and eliminates the rocker beam component entirely, replacing its function with a simpler system of pivot fittings that attach the cross tubes directly to the keel beams. This removes unnecessary structural elements while preserving the resonance prevention capability.
2Ease of repair
If pivot bolts are made accessible for maintenance, then ease of repair is improved, but weight and device complexity increase due to access panels
Solution Approach 1:
The pivot fitting design allows maintenance personnel to access and service the pivot bolts from the exterior of the aircraft without requiring interior access panels. The fittings are positioned and configured so that all maintenance activities can be performed from outside the fuselage, eliminating the need for additional access structures.
3Reliability
If rocker beams are used to prevent resonance, then aircraft stability is improved, but drag increases
Solution Approach 1:
The invention removes the rocker beam component that creates aerodynamic drag, replacing it with a streamlined configuration of cross tubes and pivot fittings that present minimal resistance to airflow while maintaining the necessary structural function.
4Reliability
If heavy rocker beams are used, then aircraft stability is improved, but weight increases
Solution Approach 1:
The invention replaces the single heavy rocker beam with multiple lighter components (forward cross tube, aft cross tube, pivot fittings, and keel beam attachments) that distribute the structural function across several elements, reducing overall weight while maintaining stability.
Solution Approach 2:
The invention uses simpler, lighter pivot fittings that can be easily replaced if needed, rather than relying on heavy, permanent rocker beam structures. This approach prioritizes lightweight components that fulfill the functional requirement without excessive weight.
Data Source
AI summary
A multi-piece pivot fitting for use on aircraft with skid type landing gear has a forward fitting, and aft fitting, and at least a lower strap. This configuration allows cross tube loads to be transferred to the keel beams of the aircraft, thereby allowing selected longitudinal rocking of the aircraft and preventing the aircraft from going into a resonance state.