Helicopter Flexbeam Rotor Hub Spherical Bearing Support
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Solution Overview
Problem
Conventional flex beam rotor heads for helicopters face challenges in aerodynamic efficiency due to geometrical constraints and twisting of flex beams, which restricts the range of pitch change and affects service life.
Innovation Solution
A rotor hub assembly with flex beams that are spherically supported by inner bearings, allowing for rotation about the beam pitch axis and reducing torsional twist, enabling a smaller, lighter rotor with improved drag profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flex beams are clamped to accommodate blade pitch changes, then the rotor can achieve acceptable service life, but the aerodynamic efficiency is degraded due to geometrical constraints and twisting
Solution Approach 1:
The invention divides the support function into two separate bearing systems: inner bearings that spherically support the flex beams at the hub, and outer bearings that support the flex beams at the blade attachment point. This segmentation allows each bearing system to handle specific aspects of the pitch motion independently, reducing torsional twist in the flex beams while maintaining the full range of pitch change capability, thus preserving aerodynamic efficiency without compromising service life
Solution Approach 2:
The inner spherical bearings act as an intermediary mechanism between the rotor hub and the flex beams. By providing spherical support that allows rotation about the beam pitch axis, these bearings mediate the pitch motion in a way that accommodates blade pitch changes while minimizing the induced twist in the flex beams, thereby resolving the conflict between reliability and aerodynamic efficiency
2Reliability
If flex beams are designed to handle full pitch change range, then service life is improved, but the rotor size and weight increase due to geometrical constraints
Solution Approach 1:
By segmenting the support function into inner and outer bearings, the invention allows the flex beams to be optimized for a reduced pitch change range in each section, enabling the use of lighter, more efficient beam geometries while still achieving the full required pitch change capability through the combined action of both bearing systems
Solution Approach 2:
The invention changes the support parameters from fixed clamping to spherical bearing support, which fundamentally alters how pitch motion is accommodated. This parameter change allows the flex beams to rotate freely about the pitch axis without inducing torsional twist, enabling lighter beam designs that maintain service life while reducing overall rotor weight
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 aerodynamic efficiency and extends the service life of the rotor by accommodating pitch changes without inducing twist in the flex beams, resulting in a more efficient and durable rotor system.
Implementation Method 1
One or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub
Implementation Method 2
allowing for rotation about the beam pitch axis and reducing torsional twist
Data Source
AI summary
A rotor hub assembly for a helicopter includes a rotor hub operably connectable to a shaft of a helicopter. One or more flex beams extend through the rotor hub, with each end of each flex beam operably connectable to a rotor blade. One or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub. A rotor assembly for a helicopter includes a rotor hub operably connectable to a shaft of a helicopter. One or more flex beams extending through the rotor hub and one or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub. A plurality of rotor blades are operably connected to the ends of the one or more flex beams.