Rotorcraft Tail Rotor Balancing with Deformable Compensation Masses
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Solution Overview
Problem
Current rotorcraft tail rotor systems face issues with mechanical stresses and increased maintenance costs due to high static and dynamic forces during pitch angle variations, particularly when hydraulic assistance fails, and existing solutions like Chinese masses and gyroscopic mechanisms are either ineffective or costly.
Innovation Solution
A tail rotor design featuring compensation masses with deformable portions that move parallel to the blade's main axis of inertia, allowing for reduced mechanical stresses and dynamic forces, and a method for balancing the rotor using these deformable compensation masses to optimize force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic assistance is used to counter the flat return torque, then ease of operation is improved, but reliability deteriorates due to potential hydraulic system failures
Solution Approach 1:
The patent introduces compensating masses as intermediary elements that mediate between the blade's aerodynamic forces and the pitch control system. These masses generate counteracting moments through their positioning and movement, reducing the hydraulic assistance needed while providing a passive, reliable mechanism that doesn't depend on hydraulic system integrity.
Solution Approach 2:
The compensating masses function as counterweights that generate moments opposite to the flat return torque. By positioning these masses at specific locations and allowing them to move or adjust, the system creates a passive counterbalancing effect that reduces the force required for pitch control without relying on hydraulic assistance.
2Power
If blade surface area is increased to handle more powerful engines, then power handling capacity is improved, but mechanical stress on bearings and control rods increases
Solution Approach 1:
The compensating masses act as counterweights that generate moments to counterbalance the increased forces from larger blade surface areas. By strategically positioning and moving these masses, the system offsets the additional mechanical stresses transmitted to bearings and control rods, enabling the use of larger blades without proportionally increasing stress on support structures.
Solution Approach 2:
The patent employs dynamic compensating masses that can move or adjust their position during rotor operation. This dynamic adjustment allows the compensating masses to optimally counterbalance varying forces throughout the rotation cycle, effectively reducing peak mechanical stresses on bearings and control rods while maintaining power handling capacity.
3Manufacturing precision
If static and dynamic balancing is performed using traditional methods, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The compensating masses serve multiple functions: they provide static balancing, dynamic balancing, and active counterbalancing of operational forces. This multi-functionality eliminates the need for separate balancing mechanisms and complex adjustment systems, achieving high balancing precision while maintaining relatively simple device architecture.
Solution Approach 2:
The patent uses dynamic compensating masses that can adjust their position during rotor operation to achieve optimal balancing. This dynamic approach allows a single mechanism to handle both static and dynamic balancing requirements, as well as ongoing force compensation, without requiring multiple separate systems or complex manufacturing procedures.
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 design significantly reduces mechanical stresses on laminated bearings and pitch control rods, enhances safety, and maintains efficient operation at maximum engine power, while being simpler and less costly to implement, thus improving maintenance intervals and reducing operational expenses.
Implementation Method 1
compensation masses with deformable portions that move parallel to the blade's main axis of inertia, allowing for reduced mechanical stresses and dynamic forces
Implementation Method 2
the centrifugal forces acting on each blade element have the effect of opposing any variation in pitch and bringing the blades back into the plane of rotation
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a rotorcraft tail rotor comprising at least two blade elements (1), each blade element (1) being capable of pivoting about a Z-axis of variation of a collective pitch to vary said collective pitch of each blade element of said tail rotor, each blade element (1) comprising at least one compensating mass (2) having a protrusion (4) emerging substantially perpendicular to a principal axis of inertia (5) of said blade element (1), said principal axis of inertia (5) being parallel to a longitudinal direction of the blade element. According to the invention, the rotor is characterized in that the compensating mass (2) comprises a deformable portion (6), movable relative to the protrusion (4) in a plane P parallel to the principal axis of inertia (5) of the blade element (1).