Chordwise Rotor Blade Folding Mechanism for Tiltrotor Storage
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Solution Overview
Problem
Tiltrotor aircraft occupy a large footprint during storage, leading to undesirably large moments on the drive system when rotor blades are fully cantilevered, potentially causing damage to components.
Innovation Solution
A chordwise folding and locking mechanism using a grip assembly, harness, and linkage assembly to secure rotor blades in a stowed orientation, reducing the footprint and minimizing stress on the drive system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If rotor blades are fully cantilevered to one side of the drive system to minimize storage footprint, then the footprint is reduced, but an undesirably large moment is placed on the drive system which may cause damage to bearings or other components
Solution Approach 1:
The rotor blade folding mechanism divides the blade into multiple foldable sections (root section, intermediate section, tip section) that can be independently positioned. This segmentation allows the blade to be folded chordwise to a stowed orientation, distributing the load and reducing the moment on the drive system while maintaining a compact footprint.
Solution Approach 2:
The system employs dynamic locking mechanisms (first lock assembly and second lock assembly) that can selectively secure the rotor blade in different orientations. The linkage assembly provides dynamic control over the blade's position, allowing it to transition between radially extended and stowed orientations while managing the moments applied to the drive system through controlled positioning.
2Area of stationary object
If rotor blades are folded beamwise to be parallel to the wing, then the footprint is reduced, but the moment on the drive system remains undesirably large
Solution Approach 1:
Instead of folding the rotor blades beamwise (lateral direction), the invention folds them chordwise (front-to-back direction relative to the blade). This dimensional change in the folding direction allows the blades to be stowed parallel to the wing while significantly reducing the moment on the drive system by repositioning the blade mass closer to the drive system's rotational axis.
3Reliability
If lock assemblies are used to secure rotor blades in stowed orientation, then the drive system is protected from damage, but the device complexity increases
Solution Approach 1:
The lock assemblies are designed to automatically engage and disengage based on the rotor blade's position. The linkage assembly works in conjunction with the lock assemblies to provide self-locking functionality, where the mechanical motion of folding the blade automatically triggers the locking mechanism, reducing the need for complex external control systems while ensuring reliable protection of the drive system.
Data Source
AI summary
An apparatus for chordwise folding and locking of rotor systems includes a grip assembly and a harness disposed at least partially within and coupled to the grip assembly. A rotor blade is rotatably coupled to the grip assembly and the harness. The rotor blade has a radially extended orientation and a stowed orientation. A linkage assembly has a first end, a second end and a pivot joint therebetween. The first end of the linkage assembly is rotatably coupled to the harness and the second end of the linkage assembly is rotatably coupled to the rotor blade. A first lock assembly selectively secures the rotor blade to the grip assembly and the harness when the rotor blade is in the radially extended orientation. A second lock assembly selectively secures the rotor blade relative to the harness when the rotor blade is in the stowed orientation.