Fly-By-Wire Trim Control for Mistrim Takeoff Rotation

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Solution Overview

Problem

Current aircraft systems require manual adjustment of horizontal stabilizer and trim tabs for pitch trim during takeoff, which can lead to mistrim scenarios affecting takeoff controllability and safety margins due to varying CG configurations and thrust conditions.

Innovation Solution

A fly-by-wire system automatically adjusts the horizontal stabilizer or trim tab during takeoff based on sensors and flight parameters to ensure proper pitch trim, providing automatic assistance if the aircraft fails to rotate within a predefined time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual trim adjustment is used during takeoff, then the pilot has direct control over pitch trim settings, but the risk of mistrim scenarios increases due to varying CG configurations and thrust conditions

Engineering Contradiction:

Improvetakeoff safetyVSAvoidmanual trim adjustment complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system automatically adjusts the horizontal stabilizer and trim tabs based on sensor data from CG position, thrust settings, and flight phase detection, eliminating the need for manual trim adjustment by the pilot during takeoff operations

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system continuously monitors flight parameters including CG position, thrust settings, and aircraft attitude, using this feedback to automatically adjust trim settings and maintain proper pitch control during takeoff and flight transitions

Inventive Principle:

Principle #23Feedback

2Reliability

If automatic trim adjustment is implemented during takeoff, then the risk of mistrim scenarios is reduced, but the system complexity increases

Engineering Contradiction:

Improvepitch trim accuracyVSAvoidfly-by-wire system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fly-by-wire control system performs multiple functions including flight path control, stability augmentation, and automatic trim adjustment, consolidating these functions into a single integrated system rather than separate dedicated mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system replaces manual mechanical trim adjustment with an electronically controlled actuation system that uses sensors, processors, and motors to automatically position the horizontal stabilizer and trim tabs based on flight conditions

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If the horizontal stabilizer is adjusted during takeoff rotation, then proper pitch trim is achieved, but the takeoff procedure becomes more complex

Engineering Contradiction:

Improvetakeoff procedure simplicityVSAvoidcontrol surface adjustment complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The system pre-calculates and positions the horizontal stabilizer and trim tabs to the appropriate settings before takeoff based on loaded CG position and thrust configuration, ensuring proper pitch trim is already established when rotation begins

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts trim settings based on real-time flight conditions, allowing the horizontal stabilizer and trim tabs to move automatically in response to changing CG position, thrust levels, and flight phase rather than requiring fixed pre-set positions

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12493302B2Longitudinal trim control movement during takeoff rotation

Publication Date: 2025.12.09 EMBRAER SA

AI summary

An aircraft fly-by-wire control system allows takeoffs with a single initial horizontal stabilizer or trim tab position while maintaining satisfactory rotation times, thus allowing simpler aircraft operation and avoiding the scenario in which the crew does not correctly trim the aircraft (mistrim takeoff scenario) which could reduce safety margins.