Aircraft Jet Thrust Control During Takeoff
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Solution Overview
Problem
Short takeoff runways limit the maximum weight of commercial aircraft on takeoff due to the need for reduced thrust levels, which restricts performance and increases fuel load, making it difficult to maintain profitability while ensuring safe acceleration and braking distances.
Innovation Solution
A method and device for controlling jet thrust during takeoff, involving multiple thrust levels: starting at maximum thrust, reducing to a lower level when reaching a predetermined speed below the minimum ground control speed, and potentially increasing again when exceeding that speed, allowing for optimized weight management and reduced acceleration-stop distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reduced thrust level is used during takeoff, then the minimum ground control speed is reduced and acceleration-stop distance is decreased, but the maximum takeoff weight is limited and aircraft performance is reduced
Solution Approach 1:
The patent applies dynamic thrust adjustment by switching between different thrust levels (first thrust level and second thrust level) based on aircraft speed. The system dynamically selects thrust level P1 when speed is below threshold VA, and thrust level P2 when speed exceeds VA, allowing the aircraft to optimize both acceleration performance and ground control capability throughout the takeoff roll.
Solution Approach 2:
The patent changes the thrust parameter at a specific speed threshold VA during the takeoff phase. By adjusting the thrust level parameter based on speed conditions, the system resolves the contradiction between needing high thrust for weight performance and low thrust for ground control safety, achieving both objectives at different phases of the takeoff roll.
2Weight of moving object
If maximum thrust is used during takeoff, then the maximum takeoff weight can be increased, but the acceleration-stop distance increases and may exceed available runway length
Solution Approach 1:
The patent implements periodic action by applying maximum thrust (first thrust level P1) during the initial acceleration phase when speed is below VA, then switching to reduced thrust (second thrust level P2) when speed exceeds VA. This periodic thrust application pattern allows the aircraft to gain maximum speed quickly initially, then maintain control while reducing the remaining acceleration distance needed.
3Length of moving object
If reduced thrust level is used, then the acceleration-stop distance is reduced, but the payload capacity and fuel load are limited
Solution Approach 1:
The dynamic thrust management system allows the aircraft to carry higher payload and fuel by using maximum thrust initially to reduce acceleration distance, then switching to reduced thrust for the remainder of the roll. This dynamic approach enables the aircraft to meet both the ASDA constraint and the payload optimization goal that would be impossible with a static reduced thrust setting.
Data Source
AI summary
The disclosure herein relates to a method of controlling the thrust of the jets of a multi-jet aircraft, during the aircraft takeoff phase, which successively comprises a first step of controlling the jets to a first thrust level, until the aircraft reaches a first predetermined speed, and a second step of controlling the jets to a second thrust level, less than the first thrust level, when the aircraft exhibits a speed greater than the first predetermined speed, the first predetermined speed being less than the minimum ground control speed of the aircraft when the jets are at the second thrust level.