Rotorcraft Skid Landing Gear With Vertical Tension-Bolt Attachment
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Solution Overview
Problem
Existing skid-type landing gears for rotorcrafts have complex and cumbersome attachment mechanisms that complicate maintenance and exchangeability, often involving lateral connections with shear bolts and bushings, which are prone to corrosion and interference with the ground surface.
Innovation Solution
A skid-type landing gear with vertical attachments using tension bolts located on the upper area of the skids, transferring load via tension and pressure between the skid shoes and skids, allowing for a direct load path and simplified assembly, with optional gliding anchor nut plates for easy replacement and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lateral connections with shear bolts and bushings are used to attach cross tubes to skids, then the attachment can withstand landing loads, but the device complexity increases and maintenance becomes difficult
Solution Approach 1:
The patent inverts the traditional lateral attachment approach by using vertical attachments with tension bolts instead of shear bolts. The tension bolts are subjected to tension forces rather than shear forces, and the load path is redirected vertically through the skid structure. This inversion simplifies the attachment mechanism while maintaining strength, as the tension bolts directly engage with the skid structure without requiring complex lateral connection elements like bushings and shear bolts.
2Strength
If lateral connections with shear bolts and bushings are used, then the attachment can withstand landing loads, but the ease of repair deteriorates due to corrosion and interference with ground surface
Solution Approach 1:
The patent extracts the problematic lateral connection elements (shear bolts and bushings) from the attachment system and replaces them with vertical tension bolts. This removal eliminates the components that are prone to corrosion and interference with the ground surface, thereby improving maintainability while preserving the structural strength through the simplified vertical attachment path.
3Device complexity
If vertical attachments with tension bolts are used, then the device complexity is reduced and maintenance is easier, but the load transfer mechanism changes from shear to tension
Solution Approach 1:
The patent changes the stress parameter from shear stress (in traditional lateral attachments) to tension stress (in vertical attachments with tension bolts). This parameter change fundamentally alters the load transfer mechanism, but it also simplifies the attachment design. The tension bolts directly engage with the skid structure, creating a straightforward load path that is easier to design, manufacture, and maintain, while still effectively transferring landing loads.
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 vertical attachment design reduces component complexity, weight, and cost, provides increased design space for equipment, enhances aerodynamic cleanliness, and facilitates easy maintenance, while minimizing corrosion and interference with the ground surface.
Implementation Method 1
The vertical attachment is configured to enable load transfer from the at least one of the at least two cross tubes to the at least one of the at least two skids by tension in the predetermined number of fasteners
Implementation Method 2
The pressure plate is attached to the at least one of the at least two skids by means of a vertical attachment via a predetermined number of fasteners. The vertical attachment is configured to enable load transfer from the at least one of the at least two cross tubes to the at least one of the at least two skids by tension in the predetermined number of fasteners and by pressure between the pressure plate and the at least one of the at least two skids.
Data Source
Figure 1
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Figure 4~5
AI summary
The invention relates to a skid-type landing gear (10) for a rotorcraft (1), which comprises at least two skids (11) which are connected to each other via at least two cross tubes (13). Each cross tube (14) is connected to the skids (12) via connecting components (17), each comprising a pressure plate (17b). The pressure plates (17b) are respectively attached to the skids (12) by means of vertical attachments (29) via a predetermined number of fasteners (22). The vertical attachments (29) are configured to enable load transfer from the cross tubes (14) to the skids (12) by tension in the predetermined number of fasteners (22) and by pressure between the pressure plates (17b) and skids (11).