Differential Thrust Yaw Control for Low-Speed Blown Lift Aircraft
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Solution Overview
Problem
Conventional aircraft control systems face challenges in managing undesired yaw conditions, particularly at low airspeeds, where aerodynamic control surfaces have limited authority, and frequent rudder cycling occurs, leading to inefficient compensation for yaw oscillations and potential engine failures.
Innovation Solution
A differential thrust control system for blown lift aircraft, utilizing a computing device to selectively operate thrust-producing devices, rudder, and roll control devices based on sensor inputs and mode settings, allowing for automatic application of differential thrust to stabilize the aircraft and reduce the need for a large rudder or vertical tail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aerodynamic control surfaces are used at low airspeeds, then the aircraft can maintain basic control, but the control authority is limited and frequent rudder cycling occurs
Solution Approach 1:
The patent combines aerodynamic rudder control with differential thrust control from multiple engines into a unified control system. The flight control system integrates both control mechanisms to work together, allowing the differential thrust to augment the limited rudder authority at low airspeeds and reduce the need for frequent rudder cycling.
Solution Approach 2:
The patent introduces differential thrust as an intermediary control mechanism between the pilot's control inputs and the aircraft's yaw response. By modulating the thrust of individual engines, the system provides an additional layer of control that enhances rudder effectiveness without requiring direct pilot manipulation of the rudder at high frequencies.
2Reliability
If a large rudder and vertical tail are used to compensate for yaw moments, then yaw control authority is improved, but the aircraft size and weight increase
Solution Approach 1:
The patent replaces the need for oversized aerodynamic control surfaces with a differential thrust mechanism. Instead of relying solely on a large rudder and vertical tail to generate yaw control moments, the system uses the thrust differential from multiple engines to produce the necessary yaw control authority, thereby avoiding the weight penalty of enlarged aerodynamic structures.
3Reliability
If differential thrust control is implemented, then yaw control authority is improved and rudder size can be reduced, but the system complexity increases
Solution Approach 1:
The patent implements a flight control system that serves multiple functions: it manages conventional aerodynamic control surfaces, coordinates differential thrust from multiple engines, and integrates sensor data for comprehensive aircraft attitude monitoring. This universal control system handles both aerodynamic and propulsive control tasks, reducing the need for separate dedicated systems and managing complexity through consolidation.
4Reliability
If autofeather or engine shutoff functions are used to compensate for engine failure, then yaw stability is improved, but the response time and control precision are limited
Solution Approach 1:
The patent implements a dynamic differential thrust control system that can rapidly modulate engine thrust levels in response to detected yaw conditions or engine failures. Unlike static autofeather or engine shutoff functions, this system provides continuous, adjustable thrust differential control that adapts to changing flight conditions, offering both faster response times and more precise control authority.
Data Source
AI summary
An aircraft may include a tail having a rudder and a pair of wings. The pair of wings may include at least one flap and at least one roll control device. The aircraft may also include at least two thrust-producing devices. The aircraft may also include a differential thrust control system including a computing device having at least one processor. The at least one processer may be configured to control an attitude of the aircraft by selectively operating the at least two thrust-producing devices, the rudder, and the at least one roll control device based at least in part on a plurality of conditions provided by a plurality of sensors on the aircraft and a selected mode setting of a mode control panel. The computing device may be communicatively coupled to the at least two thrust-producing devices, the rudder, and the at least one roll control device.