Dual Axis Bifilar Vibration Absorber for Rotary Wing Aircraft
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Solution Overview
Problem
Current bifilar vibration absorbers in rotary wing aircraft are effective only in reducing vibrations along the plane of rotor blade rotation, leaving vibrations in the perpendicular plane unaddressed.
Innovation Solution
A dual axis bifilar vibration absorber system is introduced, comprising two bifilar vibration absorbers positioned along perpendicular axes, allowing each mass to be selectively pivotable about its respective axis to attenuate vibrations in both planes, thereby reducing vibrations along both axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If two separate bifilar vibration absorbers are added to address vibrations in both planes, then vibration attenuation capability is enhanced in both directions, but device complexity increases
Solution Approach 1:
The two bifilar vibration absorbers are merged into a single integrated assembly mounted on the rotor hub. The first and second absorbers are positioned adjacent to each other with their supports and masses coordinated to work together as a unified system. This merging approach reduces the overall complexity compared to installing two completely separate systems while maintaining the dual-axis vibration attenuation capability.
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 dual axis bifilar vibration absorber system effectively reduces vibrations in both the plane of rotor blade rotation and the perpendicular plane, enhancing the overall vibration attenuation capability of rotary wing aircraft without increasing aerodynamic drag.
Implementation Method 1
During operation, the dynamic mass, acting as a pendulum, moves in a pendulous movement relative to the support. When the natural frequency of the mass is equal to a rotor excitation frequency, vibrations are either reduced or eliminated.
Implementation Method 2
The rotor blades, rotor blade control elements, and other structure which, when rotated, cause vibration.
Implementation Method 3
When the natural frequency of the mass is equal to a rotor excitation frequency, vibrations are either reduced or eliminated.
Implementation Method 4
The first mass is selectively pivotable about the second axis in order to attenuate vibration in the first axis, and the second mass is selectively pivotable about the first axis to attenuate vibration in the second axis.
Data Source
AI summary
A dual axis bifilar vibration absorber system including a first bifilar vibration absorber having a first support provided with a first cantilevered end including a first opening and a second cantilevered end including a second opening. The first opening is spaced from the second opening along a first axis. A first mass is operatively connected to the first support. A second bifilar vibration absorber is collocated with the first bifilar vibration absorber. The second bifilar vibration absorber includes a support member having a first opening element and a second opening element. The second opening element is spaced from the first opening element along a second axis that is substantially perpendicular to the first axis. A second mass is operatively connected to the support member. The first mass is selectively pivotable about the second axis, and the second mass is selectively pivotable about the first axis.