Aircraft Autothrottle Feedback for Maximum L/D Airspeed

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Solution Overview

Problem

Existing aircraft control systems struggle to dynamically adjust airspeed for optimal L/D ratio to maximize endurance and fuel efficiency due to complex and variable factors such as weight, altitude, and air density, making it difficult for pilots to maintain efficient flight conditions.

Innovation Solution

An autothrottle control system that employs closed-loop throttle control to dynamically determine and maintain the optimal airspeed for maximum L/D ratio by adjusting engine power based on real-time sensors and algorithms, incorporating manual and autothrottle inputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If pilots manually adjust airspeed to achieve optimal L/D ratio, then fuel efficiency can be improved, but the complexity of continuously monitoring and adjusting for varying weight, altitude, and air density conditions becomes excessive

Engineering Contradiction:
Improvefuel efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The autothrottle system automatically monitors flight conditions and adjusts airspeed to maintain optimal L/D ratio without pilot intervention. The system self-regulates by continuously processing sensor data and making throttle adjustments, eliminating the need for manual pilot management of these complex variable conditions.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses closed-loop feedback by continuously monitoring actual flight parameters (airspeed, altitude, weight) and comparing them against optimal values. The autothrottle automatically adjusts engine power based on this feedback to maintain the target L/D ratio, resolving the complexity of manual adjustments.

Inventive Principle:
Principle #23Feedback

2Duration of action of moving object

If aerodynamic analysis is performed to determine standard relationship between IAS and aircraft weight, then maximum L/D ratio can be achieved, but weight measurement errors and variations in engine performance reduce accuracy

Engineering Contradiction:
Improveflight enduranceVSAvoidairspeed determination accuracy
Core Design Contradiction:
Duration of action of moving objectVSMeasurement precision

Solution Approach 1:

The system continuously monitors actual flight conditions and uses closed-loop feedback to adjust airspeed in real-time. This ongoing measurement and adjustment process compensates for initial inaccuracies from weight measurements and engine performance variations, maintaining accurate optimal airspeed throughout the flight.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the target airspeed based on current flight conditions including changing weight, altitude, and engine performance. Rather than relying on fixed pre-calculated values, the system adapts continuously to maintain optimal L/D ratio despite varying conditions.

Inventive Principle:
Principle #15Dynamics

3Productivity

If autothrottle control is used to dynamically adjust airspeed, then near-optimal flight endurance is achieved, but the system complexity increases compared to manual control

Engineering Contradiction:
Improveoperational efficiencyVSAvoidthrottle control system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The autothrottle system integrates multiple functions including airspeed control, fuel management, and flight condition monitoring into a single automated system. This multi-functionality justifies the increased complexity by providing comprehensive flight optimization that manual control cannot achieve.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system automatically manages the complex task of maintaining optimal L/D ratio without requiring pilot expertise or continuous manual adjustment. The self-service nature of the system improves operational efficiency by freeing the pilot from complex calculations and adjustments.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4154098B1Aircraft control for endurance and fuel economy
Publication Date: 2026.01.28 INNOVATIVE SOLUTIONS & SUPPORT INC
  • EP4154098B1 patent drawingFigure 1~2
  • EP4154098B1 patent drawingFigure 3
  • EP4154098B1 patent drawingFigure 4

AI summary

An autothrottle of an aircraft is configured to reduce engine power of the aircraft such that the aircraft incrementally slows from a prior airspeed to a reduced airspeed by a first increment, and compare the rates of energy consumption at the prior airspeed and the reduced airspeed. In response to the rate of energy consumption at the reduced airspeed being lower than at the prior airspeed as determined the above operations are repeated. In response to the rate of energy consumption at the reduced airspeed not being less than at the prior airspeed, the autothrottle increases the engine power such that the aircraft incrementally speeds up from a prior airspeed to an increased airspeed by a second increment, the increased airspeed corresponding to a more efficient operating point of the aircraft than any prior airspeed.