Tiltable Tail Rotor for High-Speed Rotary-Wing Aircraft
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Solution Overview
Problem
Conventional helicopters are limited in speed due to the high rotation speed of their main rotor, which leads to reduced component lifespan and increased vibrations, and existing solutions for high-speed flight either degrade components or require tilting the rotor, which is detrimental to the transmission system.
Innovation Solution
A method for piloting a rotary-wing aircraft with a tilting tail rotor that can pivot from an anti-torque mode to a propulsion mode, allowing the tail rotor to control yaw and contribute to propulsion, reducing the main rotor's pitch and load, thereby enabling high-speed flight without degrading the transmission chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the main rotor rotation speed is increased to achieve high forward speed, then the aircraft speed is improved, but the component service life is reduced and vibrations increase
Solution Approach 1:
The propulsion function is segmented between the main rotor and the tilting tail rotor. The tail rotor can operate in two modes: anti-torque mode (traditional helicopter operation) and propulsion mode (contributing to forward thrust). This segmentation allows the main rotor to operate at lower speeds while achieving high forward speed through combined thrust from both rotors, thereby extending component service life and reducing vibrations.
Solution Approach 2:
The tail rotor is designed with dynamic tilting capability, allowing it to change its orientation between anti-torque mode and propulsion mode. This dynamic reconfiguration enables the aircraft to transition between different flight regimes, optimizing performance while protecting the main rotor transmission system from excessive stress at high speeds.
2Speed
If the main rotor rotation speed is increased to achieve high forward speed, then the aircraft speed is improved, but vibrations increase
Solution Approach 1:
By dividing the thrust production between two rotors (main rotor and tilting tail rotor), the system avoids the need for the main rotor to operate at excessively high speeds. The tail rotor in propulsion mode contributes additional thrust, allowing the main rotor to maintain lower, smoother operating speeds that generate fewer vibrations.
3Adaptability or versatility
If the tail rotor is used for both anti-torque and propulsion functions, then the device complexity increases
Solution Approach 1:
The tail rotor is designed as a multi-functional component that can perform both anti-torque control and propulsion functions. By making the tail rotor universal, the system avoids adding a separate pusher propeller, thereby limiting the increase in device complexity while achieving enhanced versatility and high-speed capability.
4Speed
If the main rotor pitch is reduced to enable high-speed flight, then the aircraft speed is improved, but the lift generation is reduced
Solution Approach 1:
The lift and propulsion functions are merged into a coordinated system. The main rotor maintains sufficient pitch to generate adequate lift, while the tilting tail rotor in propulsion mode provides additional forward thrust. This combination allows the main rotor pitch to be reduced from conventional high-speed configurations while maintaining both lift and forward speed performance.
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
Enables rotary-wing aircraft to achieve high forward speeds without significant degradation of components, as the tail rotor participates in propulsion, reducing the load on the main rotor and extending its service life.
Implementation Method 1
a rear rotor capable of pivoting to switch reversibly from an anti-torque operating mode during which the tail rotor is capable of controlling the yaw movement of the aircraft to a propulsion operating mode during which the tail rotor is capable of pivoting about a tilt axis
Implementation Method 2
at least one rotary wing comprising a plurality of first blades having a first variable pitch in order to ensure at least the lift of the aircraft
Implementation Method 3
a rear rotor capable of pivoting about a tilting axis to contribute to the propulsion of the aircraft
Implementation Method 4
a rear rotor capable of countering the torque generated by the rotary wing on the cell of the aircraft
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The method involves controlling pitch of a set of blades (12) of a tail rotor (10) of an aircraft (1) using a control unit (31) in an anti-torque mode of operation, and controlling a salient angle (theta) of a rotation axis (AX) using the control unit. The pitch of set of blades of the tail rotor of the aircraft is controlled using another control unit (32) in a propulsion mode of operation. The tail rotor is swiveled to move reversibly from the anti-torque mode of operation to the propulsion mode of operation. An independent claim is also included for an aircraft comprising an airframe carrying a rotary wing including a set of blades.