Directional Tail Thrust System for Rotorcraft
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Solution Overview
Problem
Traditional tail rotors in helicopters suffer from issues such as blade stall, noise generation, structural integrity concerns, and inability to provide forward thrust, leading to inefficiencies and safety hazards.
Innovation Solution
A directional tail thrust system featuring a tailboom with an internal air passage and a pivotable vane array that can switch between anti-torque, forward thrust, and pro-torque modes, utilizing a fan to direct air through the vane array for thrust production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a traditional tail rotor is used to counteract torque, then anti-torque capability is provided, but noise is significantly generated and forward thrust cannot be produced
Solution Approach 1:
The vane array is made dynamically adjustable with vanes that can pivot between different positions to change the direction of air flow. This allows the system to adapt between anti-torque mode (vanes positioned laterally), forward thrust mode (vanes positioned forward), and other intermediate configurations, replacing the static traditional tail rotor with a dynamic flow control system
Solution Approach 2:
The invention uses a fan-driven air flow system with diffusers and vanes to control thrust generation. Instead of mechanical rotating blades, pneumatic principles are applied by directing high-velocity air flow through adjustable vanes to produce both anti-torque and forward thrust, eliminating the noisy mechanical tail rotor while maintaining versatility
2Reliability
If the tail rotor rotates at high angular velocity to provide adequate aerodynamic response, then anti-torque thrust is sufficient, but blade stall occurs and structural integrity is compromised
Solution Approach 1:
The mechanical rotating tail rotor system is replaced with a pneumatic jet system using a fan, diffusers, and adjustable vanes. This substitution eliminates the high-speed rotating blades that cause blade stall and mechanical stress, replacing them with a controlled air flow system that provides equivalent anti-torque effectiveness without the associated structural risks
Solution Approach 2:
The dangerous high-speed rotating blade component is extracted and removed from the system. The anti-torque function is achieved through a different mechanism (adjustable vanes directing air flow) that does not require high-angular-velocity rotation, thereby eliminating blade stall and reducing structural stress on the tailboom
3Reliability
If the tail rotor continues to rotate at high speed in forward flight, then anti-torque control is maintained, but unnecessary noise is produced and forward flight efficiency is diminished
Solution Approach 1:
The system transitions from a continuously rotating mechanical tail rotor to a dynamic flow control system where the fan speed and vane position can be independently adjusted. In forward flight, the fan can operate at lower speeds while vanes are positioned to provide adequate yaw control, reducing noise and drag while maintaining productivity
Solution Approach 2:
The invention allows independent control of multiple parameters: fan rotational speed, vane angle, and air flow rate. In forward flight conditions, these parameters can be optimized to reduce fan speed (lowering noise and drag) while adjusting vane position to maintain necessary yaw authority, thereby improving forward flight efficiency without sacrificing control reliability
4Speed
If an open rotor design is used for the tail rotor, then aerodynamic response is improved, but safety hazard increases due to exposed blades
Solution Approach 1:
The exposed mechanical rotor blades are replaced with an enclosed pneumatic system consisting of a fan housed within the tailboom and adjustable vanes at the exit. This enclosed design eliminates the safety hazard of exposed rotating blades while maintaining rapid aerodynamic response through the adjustable vanes that can quickly redirect air flow in response to control inputs
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 system enhances efficiency by reducing noise, providing forward thrust, and improving structural integrity while maintaining effective anti-torque capabilities, offering a safer and more maneuverable alternative to traditional tail rotors.
Implementation Method 1
a fan in fluid communication with the aft diffuser and a vane array including vanes coupled to the aft diffuser and configured to receive air from the fan via the aft diffuser
Implementation Method 2
The vanes are pivotable to switch the vane array between various modes including an anti-torque mode to produce anti-torque thrust, a forward thrust mode to produce forward thrust and a pro-torque mode to produce pro-torque thrust
Implementation Method 3
The aft portion of the internal air passage includes an aft diffuser
Data Source
AI summary
A directional tail thrust system for a helicopter includes a tailboom defining an internal air passage. The aft portion of the internal air passage includes an aft diffuser. The directional tail thrust system also includes a fan in fluid communication with the aft diffuser and a vane array including vanes coupled to the aft diffuser and configured to receive air from the fan via the aft diffuser. The vanes are pivotable to switch the vane array between various modes including an anti-torque mode to produce anti-torque thrust, a forward thrust mode to produce forward thrust and a pro-torque mode to produce pro-torque thrust.