Aircraft Thrust Control for Constant-Acceleration Takeoff
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Solution Overview
Problem
Aircraft takeoff procedures often result in peak acceleration early in the takeoff run, causing passenger discomfort, and derated takeoffs, while reducing engine strain, require additional runway length and still experience higher acceleration initially.
Innovation Solution
A flight control system with a variable engine thrust takeoff mode that uses inertial sensors and airspeed sensors to adjust engine thrust in real-time, maintaining a constant acceleration by increasing thrust as speed increases, thereby reducing peak acceleration and shortening the takeoff run.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If full engine thrust is used during takeoff, then acceleration is sufficient to achieve liftoff, but peak acceleration early in the takeoff run causes passenger discomfort
Solution Approach 1:
The patent implements a variable thrust system that dynamically adjusts engine thrust during the takeoff run. The thrust level transitions from a lower initial value to a higher final value as the aircraft accelerates, allowing the system to maintain sufficient overall acceleration while reducing the peak acceleration that causes passenger discomfort. This is achieved through continuous adjustment based on measured acceleration feedback.
Solution Approach 2:
The system changes the thrust parameter over time during the takeoff sequence. By varying the thrust level as a function of aircraft speed and acceleration, the system optimizes the balance between achieving liftoff and minimizing passenger discomfort. The thrust parameter is adjusted continuously rather than remaining fixed.
2Strength
If derated thrust is used to reduce engine strain, then engine strain is reduced, but additional runway length is required and acceleration is still high initially
Solution Approach 1:
The variable thrust system dynamically increases engine thrust during the takeoff run, allowing the aircraft to achieve sufficient acceleration without requiring excessive runway length. This dynamic adjustment enables the system to use less than maximum available thrust initially while still achieving liftoff within the available runway, thereby reducing engine strain without sacrificing takeoff performance.
3Ease of operation
If fixed throttle setting is used during takeoff, then operation is simple, but acceleration varies causing peak acceleration discomfort
Solution Approach 1:
The system automatically adjusts thrust without requiring manual throttle adjustments by the pilot. The flight management system or autopilot continuously monitors acceleration and automatically modulates engine thrust to maintain optimal acceleration levels, eliminating the need for complex manual throttle management while achieving smooth acceleration.
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 effectively reduces passenger discomfort by maintaining a constant acceleration throughout the takeoff, potentially shortening the takeoff run and minimizing strain on aircraft engines, while ensuring safe liftoff conditions.
Implementation Method 1
an inertial sensor operative to detect a force on the aircraft and to generate an acceleration data signal indicative of an acceleration of the aircraft
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A flight control system for controlling an aircraft during a variable engine thrust takeoff operation operative to perform a method including calculating a calculated acceleration in response to a takeoff distance and a selection of a variable engine thrust takeoff mode, generating an initial thrust control signal in response to the calculated acceleration, controlling a thrust of an aircraft engine in response to the initial thrust control signal, measuring a measured acceleration of the aircraft, generating an updated thrust control signal in response to a difference between the calculated acceleration and the measured acceleration, and controlling the thrust of the aircraft engine in response to the updated thrust control signal.