Aircraft Engine Acceleration Scheduling to Reduce Asymmetric Thrust

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Solution Overview

Problem

Aircraft experience asymmetric thrust during takeoff when engines on opposite sides spool up at different rates, leading to loss of directional control and potential runway deviations.

Innovation Solution

Implementing thrust controllers to detect and adjust the acceleration schedule of individual engines based on N1 speed differences, applying modifiers to equalize thrust between engines during specific conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If engines spool up at different rates during takeoff, then takeoff power is achieved, but asymmetric thrust causes loss of directional control

Engineering Contradiction:
Improveengine spool-up rateVSAvoiddirectional control
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

The thrust controller continuously monitors N1 speeds of multiple engines and dynamically adjusts acceleration schedules based on detected asymmetries. This closed-loop feedback system detects thrust imbalances and applies corrective modifiers to individual engine acceleration profiles, maintaining directional control while achieving takeoff power.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system modifies engine acceleration parameters by applying modifiers to acceleration schedules based on detected N1 speed differences. When asymmetric thrust is detected, the controller changes the acceleration rate parameters of individual engines to equalize thrust output, resolving the directional control issue while maintaining takeoff performance.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If thrust controllers monitor and adjust individual engine acceleration, then asymmetric thrust is reduced, but system complexity increases

Engineering Contradiction:
Improvethrust symmetryVSAvoidcontrol system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The thrust controller performs multiple functions within a single system: it monitors N1 speeds of all engines, detects asymmetric thrust conditions, calculates appropriate modifiers, and adjusts acceleration schedules. This multi-functional approach achieves thrust symmetry without requiring separate dedicated systems for each function, managing complexity through integration.

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

Data Source

PatentEP4644255A1Mitigation of asymmetric thrust for aircraft
Publication Date: 2025.11.05 PRATT & WHITNEY CANADA CORP
  • EP4644255A1 patent drawingFigure 1
  • EP4644255A1 patent drawingFigure 2
  • EP4644255A1 patent drawingFigure 3

AI summary

A method includes detecting an asymmetric thrust condition involving first and second engines of an aircraft. The asymmetric thrust condition is associated with one of the engines providing more thrust than another of the engines. The method also includes, in response to detecting the asymmetric thrust condition, determining a modifier (216) for one of the engines and applying the modifier to an acceleration schedule (220) for that engine. The modifier (216) alters the acceleration schedule (220) for that engine to reduce asymmetric thrust between the engines.