Independent Yaw Authority in Distributed-Thrust Aircraft Transition
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Solution Overview
Problem
Current VTOL aircraft face challenges in control during hover and transition between thrust-borne and wing-borne flight modes, particularly due to downwash inefficiencies and complex control requirements.
Innovation Solution
The aircraft employs a distributed thrust array with multiple independent yaw authority mechanisms, including differential speed control of rotor assemblies, differential longitudinal control surface maneuvers, and differential thrust vectoring, to achieve stable and efficient flight operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tiltrotor aircraft use fixed wing during vertical takeoff and landing, then structural support is provided, but downwash inefficiencies occur due to interference from the fixed wing
Solution Approach 1:
The aircraft separates the functions of lift generation and thrust provision by removing the fixed wing during vertical operations, allowing the propellers to operate independently without aerodynamic interference from wing structures, thus eliminating downwash inefficiencies while maintaining structural support through the airframe and landing gear
Solution Approach 2:
The aircraft employs dynamic reconfiguration where the fixed wing is selectively deployed or removed based on flight phase - present during forward flight for lift, and absent during vertical operations to eliminate interference - optimizing performance for each operational mode
2Loss of energy
If tiltwing aircraft use vertically tilted wing for vertical takeoff and landing, then slipstream efficiency is improved, but control during hover becomes more difficult due to large surface area exposed to crosswinds
Solution Approach 1:
The aircraft separates the wing function from the vertical lift function by using independent proprotors mounted on nacelles that can operate vertically without the wing in the way, eliminating the crosswind exposure problem while maintaining slipstream efficiency through proper propeller positioning and rotation plane orientation
Solution Approach 2:
The aircraft changes the operational dimension by rotating the proprotor rotation plane from horizontal (when mounted on vertical wing) to vertical plane, allowing the thrust to be directed horizontally for forward flight while eliminating the wing's interference with the slipstream during vertical operations
3Ease of operation
If VTOL aircraft use complex control mechanisms for hover stability, then control authority is improved, but device complexity increases
Solution Approach 1:
The flight control system serves multiple functions simultaneously - it controls the cyclic rotor control for hover stability, manages the tilt mechanism for transitioning between vertical and horizontal flight, and coordinates the proprotor pitch and roll - reducing the need for separate dedicated control mechanisms for each function
Solution Approach 2:
The aircraft merges the cyclic rotor control with the tilt mechanism control, where the same control inputs that manage hover stability also drive the transition to forward flight, eliminating the need for separate control systems and reducing overall device complexity
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 configuration enables improved control and efficiency during both thrust-borne and wing-borne flight modes, enhancing the aircraft's versatility and stability, particularly in hover and transition phases.
Implementation Method 1
each having a rotor assembly operable for generating thrust
Implementation Method 2
a two-dimensional distributed thrust array including a plurality of gimbal mounted propulsion systems each operable for two-axis thrust vectoring
Implementation Method 3
A second yaw authority mechanism includes differential longitudinal control surface maneuvers of control surfaces of two symmetrically disposed tail members
Implementation Method 4
Fixed-wing aircraft are capable of flight using wings that generate lift responsive to the forward airspeed of the aircraft
Data Source
AI summary
An aircraft has multiple independent yaw authority mechanisms. The aircraft includes an airframe having first and second wings with at least first and second pylons extending therebetween and with a plurality of tail members extending therefrom each having an active control surface. A two-dimensional distributed thrust array is coupled to the airframe that includes a plurality of propulsion assemblies each having a rotor assembly and each operable for thrust vectoring. A flight control system is operable to independently control each of the propulsion assemblies. A first yaw authority mechanism includes differential speed control of rotor assemblies rotating clockwise compared to rotor assemblies rotating counterclockwise. A second yaw authority mechanism includes differential longitudinal control surface maneuvers of control surfaces of two symmetrically disposed tail members. A third yaw authority mechanism includes differential thrust vectoring of propulsion assemblies.