Aircraft Tail Cross-Flow Fan Anti-Torque System
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Solution Overview
Problem
Traditional helicopter tail rotors are susceptible to strikes, produce high noise, and create undesirable profile drag and thrust reduction during sideward flight, necessitating an improved anti-torque system with reduced noise, impact risk, and profile drag while providing thrust in multiple directions.
Innovation Solution
The implementation of cross-flow fan systems mounted on the tail section of an aircraft, which include variable thrust cross-flow fan assemblies with rotatable shrouds and adjustable blades to generate forward thrust, anti-torque, and yaw control, reducing exposure and noise through aerodynamic design and directional airflow management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional tail rotors are used, then anti-torque function is provided, but noise level increases and safety risk increases due to exposed blades
Solution Approach 1:
The patent replaces the traditional mechanical rotor blade system with a cross-flow fan system that generates anti-torque through aerodynamic means. The cross-flow fans mounted on the tail section produce thrust perpendicular to the rotor axis, eliminating the need for exposed rotating blades while providing the same anti-torque function.
Solution Approach 2:
The patent introduces a tail-mounted cross-flow fan system as an intermediary mechanism between the main rotor and the tail structure. This intermediary system absorbs the counteracting torque through aerodynamic thrust generation, preventing the need for traditional exposed rotor blades and their associated noise and safety issues.
2Loss of energy
If traditional tail rotors are used, then anti-torque is generated, but profile drag increases during flight
Solution Approach 1:
The patent employs dynamically adjustable cross-flow fan systems with variable pitch blades that can adapt their configuration based on flight conditions. This dynamic adjustment allows the system to optimize aerodynamic efficiency across different flight regimes, reducing profile drag while maintaining reliable thrust generation.
Solution Approach 2:
The patent transitions from a two-dimensional rotor blade planform to a three-dimensional cross-flow fan configuration mounted on the tail section. This dimensional change allows the anti-torque system to operate in a different spatial orientation, reducing interference with forward flight airflow and minimizing profile drag.
3Productivity
If traditional tail rotors are used, then yaw control is achieved, but thrust reduction occurs during sideward flight
Solution Approach 1:
The patent designs the cross-flow fan system to perform multiple functions: generating anti-torque, providing yaw control, and delivering efficient thrust in various flight directions including sideward flight. The variable pitch mechanism and tail mounting configuration enable the system to adapt to different flight regimes, maintaining high thrust efficiency across diverse operational scenarios.
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 cross-flow fan systems effectively reduce noise, minimize impact risk, and enhance thrust efficiency by providing directional control and reduced profile drag, improving overall aircraft performance and safety.
Implementation Method 1
The cross-flow fan systems are configured to provide a forward thrust vector on the aircraft
Implementation Method 2
the first and second cross-flow fan systems are configured to provide an anti-torque vector on the aircraft
Data Source
AI summary
In one aspect, there is provided an aircraft, including a fuselage having a longitudinal axis extending from a front portion through an aft portion; first and second tail members extending from the aft portion; a first cross-flow fan system rotatably mounted to the first tail member; and a second cross-flow fan system rotatably mounted to the second tail member. The first and second cross-flow fan systems are configured to provide a forward thrust vector and an anti-torque vector on the aircraft. The first and second cross-flow fan systems can have a rotational axis oriented generally vertically. In another aspect, there is an aircraft including a fuselage having a front portion and a tail portion; and a cross-flow fan system supported by the tail portion. Embodiments include a cross-flow fan system retrofittable onto an aircraft and methods for retrofitting an aircraft with a cross-flow fan system.