Rotorcraft Propeller Yaw Stabilization via Flapped Aerodynamic Surfaces
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Solution Overview
Problem
Current technologies do not provide a method to optimize the operation of left and right propellers in a rotorcraft with a main lift rotor driven by a power plant, particularly in hybrid helicopters, to achieve maximum efficiency and balance, leading to differential pitch issues that affect performance and maneuverability.
Innovation Solution
The use of left and right aerodynamic surfaces with flaps that can be steered to regulate the pitch of the propellers, minimizing differential pitch and optimizing operation by balancing the torque generated by each propeller, especially during low-speed and high-speed flight phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch of left and right propellers is different to stabilize the rotorcraft in yaw, then the anti-torque function is achieved, but the propellers cannot operate at maximum efficiency and differential pitch problems occur
Solution Approach 1:
The patent introduces aerodynamic surfaces with flaps as intermediary elements that generate transverse lift to counteract the torque from the main rotor. This mediator allows the propellers to maintain equal pitch for optimal efficiency while the flaps provide the necessary yaw stabilization, eliminating the need for differential propeller pitch.
Solution Approach 2:
The patent separates the yaw stabilization function from the propellers by assigning it to dedicated aerodynamic surfaces with flaps. This segmentation allows the propellers to focus solely on propulsion at optimal pitch angles while the flapped surfaces handle the anti-torque function independently.
2Ease of operation
If differential pitch control is used to perform anti-torque and steering functions, then yaw control is achieved, but power consumption increases and transmission chain life is reduced
Solution Approach 1:
The flapped aerodynamic surfaces act as intermediaries that assume the anti-torque function, allowing symmetric propeller operation. This eliminates the need for one propeller to operate at higher pitch angles, reducing overall power consumption and minimizing stress on the transmission chain.
3Ease of operation
If one propeller operates closer to maximum admissible torque to enhance maneuverability, then yaw response is improved, but the transmission chain experiences increased stress and reliability decreases
Solution Approach 1:
The flapped aerodynamic surfaces provide a counterbalancing transverse lift that offsets the torque from the main rotor. This allows both propellers to operate at equal, moderate torque levels rather than requiring one propeller to operate near its maximum torque limit, thereby protecting the transmission chain while maintaining maneuverability.
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 approach allows the propellers to operate at their maximum efficiency points, balancing torque and reducing power consumption, thereby enhancing maneuverability and reducing differential pitch, leading to improved piloting comfort and extended transmission chain life.
Implementation Method 1
a left aerodynamic surface (40) and a right aerodynamic surface (41) exerting transverse lift arranged respectively in the extension of the left and right propellers
Implementation Method 2
capable of generating a propulsive air flow
Data Source
Figure 1~3
Figure 4~7
Figure 8~11
AI summary
The method involves activating regulation of deflection angles of left and right flaps (45, 46) only during preset flight stages when yaw of a rotorcraft (1) is stabilized via respective pitches of left and right propellers (21, 22) of the rotorcraft to minimize a differential pitch between the propellers to optimize the operation of the propellers. The flight stages include low speed flight stages performed at an indicated air speed of the rotorcraft less than a threshold, and yaw-stabilized high speed flight stages performed at an indicated air speed of the rotorcraft above the threshold. An independent claim is also included for a rotorcraft comprising a main lift rotor.