Rotorcraft Blade Grip Segmentation for Flight Control Decoupling
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Solution Overview
Problem
The increasing complexity of rotorcraft systems leads to tightly coupled flight parameters and controls, making it challenging to manage flight characteristics across different speed regimes, particularly requiring significant power adjustments and anti-torque forces, which differs from fixed wing aircraft and increases pilot workload.
Innovation Solution
A structural rotorcraft blade grip system with a U-shaped or C-shaped grip assembly made from laminated composite materials, featuring a centrifugal force bearing and pitch horns, which allows for independent flapping and lead-lag movement of rotor blades, decoupling flight characteristics and reducing weight through optimized design and material orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotor blades are attached to a traditional rigid grip system, then structural strength is maintained, but flight control complexity increases and pilot workload increases
Solution Approach 1:
The grip system is segmented into multiple functional zones: a rigid inboard portion for structural attachment to the yoke, a flexible midsection with circumferential grooves for blade accommodation, and an outboard portion for blade attachment. This segmentation allows different parts to perform specialized functions - the rigid portions provide strength while the flexible midsection provides control freedom, resolving the contradiction between structural strength and control complexity.
Solution Approach 2:
The grip utilizes changes in material parameters along its length - transitioning from rigid material at the inboard end to flexible material in the midsection, and back to rigid material at the outboard end. This parameter change allows the grip to provide both structural strength where needed and flexibility for independent blade movement, reducing flight control complexity while maintaining overall structural integrity.
2Stability of the object's composition
If rotor blades are allowed independent flapping and lead-lag movement, then flight stability improves, but grip structure complexity increases
Solution Approach 1:
The flexible midsection of the grip serves itself by automatically deforming to accommodate blade flapping and lead-lag movements without requiring external actuators or complex mechanical linkages. The circumferential grooves and flexible material work together to provide the necessary degrees of freedom, allowing the grip structure itself to enable stable flight movements without adding external complexity.
3Weight of moving object
If laminated composite materials are used for the grip, then weight is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The grip employs laminated composite materials with fibers oriented in specific directions to achieve the required strength-to-weight ratio. The composite structure provides both weight reduction and inherent structural guidance that helps maintain manufacturing precision, as the layered construction naturally resists deformation and maintains dimensional stability during fabrication.
Solution Approach 2:
Different regions of the grip utilize laminates with different fiber orientations and material properties - the inboard and outboard rigid portions use laminates optimized for strength, while the midsection uses laminates optimized for flexibility. This local quality approach allows each region to meet its specific requirements without compromising overall manufacturing precision.
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 design enhances flight stability and efficiency by decoupling flight control inputs, reducing pilot workload, and optimizing power usage, while maintaining structural integrity under centrifugal forces, thus improving rotorcraft performance across various flight regimes.
Implementation Method 1
The main rotor blades are attached by main rotor blade grips to a main rotor yoke that is attached to the rotor mast. The main rotor grips securely attach the main rotor blades to the yoke through a spherical thrust bearing which permits each of the main rotor blades to independently flap vertically, rotate on a long axis to provide cyclic and collective control of the rotorcraft, and move forward or backward within the rotor plane to lead or lag the grip attachment point.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An embodiment rotorcraft main rotor system (103), including a yoke (301), a rotor blade (105), and a grip assembly (305) attaching the rotor blade to the yoke. The grip assembly (305) includes a grip body (501) formed from a contiguous laminated composite and has a substantially constant thickness, where the grip body (501) has an upper extension (315), a lower extension (317) and a connecting portion (401) connected between an inboard end of the upper extension and an inboard end of the lower extension. An inside surface of the upper extension (315) faces, and is substantially parallel to, an inside surface of the lower extension (317), and the upper extension has first features and the lower extension has second features that are aligned with the first features, where the first features and second features each include at least one of an edge contour, attachment holes (503), or first protective elements.