Blade-Fold Bushing Mechanism for Rotorcraft Storage
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Solution Overview
Problem
Existing rotor blade folding systems for rotorcraft and tiltrotor aircraft add weight and complexity due to the use of automated built-in mechanisms, which are not optimal for limited storage spaces.
Innovation Solution
A blade-fold bushing system comprising a splined bushing, a castellated bushing, a lock bushing, and a support tool, which allows for manual or automated folding of rotor blades by meshing teeth and shafts, reducing the need for heavy and complex mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automated built-in systems are used to rotate or fold rotor blades, then the folding operation can be performed automatically, but the weight and complexity of the rotor blade assembly increases
Solution Approach 1:
The automated folding system is divided into separate functional modules: an actuator that provides folding force, a bushing mechanism that guides rotation, and a lock mechanism that secures positions. This segmentation allows each component to be optimized independently and simplifies the overall system architecture.
Solution Approach 2:
The castellated bushing is inserted within the splined bushing, creating a nested configuration where the inner bushing provides fine-positioning teeth while the outer bushing provides structural support and coarse-positioning teeth. This nesting reduces the overall radial space required while maintaining complex functionality.
2Extent of automation
If automated built-in systems are used to rotate or fold rotor blades, then the folding operation can be performed automatically, but the weight of the rotor blade assembly increases
Solution Approach 1:
The castellated bushing engages with the splined bushing through interlocking teeth that automatically lock the rotor blade in folded and unfolded positions without requiring additional locking components. The system uses its own structural elements to provide the locking function, eliminating the need for separate heavy locking mechanisms.
Solution Approach 2:
The bushing mechanism uses simple, easily manufactured toothed components that can be produced cost-effectively. While the bushings themselves are durable, the design allows for economical replacement if needed, reducing the overall system weight by avoiding the use of expensive, heavy-duty components.
3Volume of moving object
If rotor blades are folded to reduce storage space, then the overall profile of the rotor assembly is reduced, but the mechanism required to fold the blades adds complexity
Solution Approach 1:
The splined bushing serves multiple functions: it provides structural support for the rotor blade, guides the folding rotation through its splined teeth, engages with the castellated bushing for position control, and works with the lock mechanism to secure folded positions. This multi-functionality eliminates the need for separate components for each function, reducing overall complexity.
Solution Approach 2:
The folding mechanism transitions between static and dynamic states: the bushings remain stationary during normal operation, but can rotate freely when folding is initiated. The lock mechanism dynamically engages and disengages to transition between locked (folded or unfolded) and unlocked (folding in progress) states, allowing the system to adapt its rigidity as needed.
Data Source
AI summary
A blade-fold bushing system includes a splined bushing comprising a first plurality of teeth, a castellated bushing comprising a second plurality of teeth and a shaft portion configured to coaxially fit within the splined bushing, and a lock bushing coaxially aligned with the castellated bushing. A support tool for use with a blade-fold bushing system includes an outer head comprising a third plurality of teeth configured to mesh with the first plurality of teeth of the splined bushing, and an inner head comprising a fourth plurality of teeth configured to mesh with the second plurality of teeth of the castellated bushing.