Rotorcraft Yaw Control via Rudder and Tail Rotor Speed Reduction
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Solution Overview
Problem
Conventional helicopter tail rotors suffer from issues such as blade stall, noise pollution, unnecessary power consumption, and structural integrity threats due to high-speed operation during forward flight, as well as inefficiencies in power distribution and balancing among multiple rotors.
Innovation Solution
A yaw control system that includes a surface-mounted tail rotor with a flight control computer implementing a rudder control module and a tail rotor rotational speed reduction module, allowing for selective switching into a rotational speed reduction mode during forward flight, which reduces tail rotor speed or shuts them off and uses a rudder for yaw control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the tail rotor is driven at high angular velocities to provide adequate aerodynamic responses to transverse airflow, then the aerodynamic response is improved, but noise emissions increase significantly
Solution Approach 1:
The tail rotor system dynamically adjusts its operational mode based on flight conditions. During forward flight, the control system reduces tail rotor speed or shuts it off entirely, switching to rudder-based yaw control. This dynamic adaptation eliminates unnecessary high-speed rotation and associated noise while maintaining adequate aerodynamic response when needed.
Solution Approach 2:
The system changes the operational parameters of the tail rotor by reducing rotational speed or shutting it off during forward flight. This parameter change directly addresses the noise issue while the rudder provides the necessary yaw control function, transforming the system from high-speed continuous operation to variable speed operation.
2Ease of operation
If the tail rotor continues to rotate at high speed in forward flight to maintain control authority, then control responsiveness is improved, but power consumption increases unnecessarily
Solution Approach 1:
The system dynamically switches between tail rotor-based control and rudder-based control depending on flight phase. During forward flight, control authority transitions to the rudder, allowing the tail rotor to reduce speed or shut off, thereby eliminating unnecessary power consumption while maintaining control responsiveness through the alternative control surface.
Solution Approach 2:
The invention extracts the yaw control function from the tail rotor during forward flight and transfers it to the rudder. This separation allows the tail rotor to stop consuming power unnecessarily while the rudder assumes the control responsibility, optimizing power distribution across flight phases.
3Force
If the tail rotor operates at high speed to provide sufficient anti-torque thrust, then thrust capability is improved, but structural integrity is threatened due to sharp load changes
Solution Approach 1:
The system dynamically adjusts tail rotor operation based on flight conditions. During forward flight, when anti-torque requirements are reduced, the tail rotor speed is reduced or shut off, preventing sharp load changes that could compromise structural integrity. The rudder provides the necessary yaw control without imposing excessive loads on the tail rotor system.
4Productivity
If multiple tail rotors are operated to balance power consumption and load, then efficiency is improved, but system complexity increases
Solution Approach 1:
The invention extracts the yaw control function from the tail rotor system during forward flight and transfers it to the rudder. This simplifies the control logic by eliminating the need for complex power balancing algorithms among multiple tail rotors, as the rudder assumes primary control responsibility in this flight phase.
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 solution reduces noise emissions, conserves power, enhances structural integrity, and improves efficiency by dynamically adjusting tail rotor speed and using the rudder for yaw control, addressing the drawbacks of traditional tail rotors.
Implementation Method 1
a rudder rotatably coupled to the surface... rotate the rudder in the rotational speed reduction mode of the one or more tail rotors to control the yaw of the helicopter
Implementation Method 2
The helicopter's tail rotor, located on a tailboom aft of the main rotor, is used to counteract this torque and control the yaw of the helicopter during flight
Data Source
AI summary
A yaw control system for a helicopter having a tailboom and a forward flight mode includes a surface coupled to the tailboom, one or more tail rotors coupled to the surface, a flight control computer implementing a yaw controller having a rudder control module and a tail rotor rotational speed reduction module and a rudder rotatably coupled to the surface. The tail rotor rotational speed reduction module is configured to selectively switch the one or more tail rotors into a rotational speed reduction mode in the helicopter forward flight mode. The rudder control module is configured to rotate the rudder in the rotational speed reduction mode of the one or more tail rotors to control the yaw of the helicopter.