Introduction to Fly-by-Wire Flight Control Systems: The professional pilot’s guide to understanding modern aircraft controls

Copyright © 2021 by David Kern

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior permission of the copyright owner.

Dedicated to professional pilots around the world – the ones that always wanted to fly, sacrificed much to achieve their dreams, and always striving to learn and improve. Your hunger for aviation knowledge creates margins of safety that will never be fully appreciated. Thank you for endeavoring to continuously learn as aviation technology races into the future.

Acknowledgements

Thanks to Reinier for asking the questions that inspired this text.

Table of Contents

Acknowledgements

Introduction

The Fundamentals of Fly-By-Wire

Fundamentals of controlled flight

Fundamental Problems with Mechanical Flight Controls

Fundamentals of Fly-By-Wire

Gain and Phase

Redundancy

Control Laws

Common Control Laws

Direct/Proportional Control Law

Angle of Attack (AoA) Command

G Command

G Command with speed scheduling

Pitch Rate Command and Flight Path Angle Command

Control Law Transitions

Sensors

Pilot Controls

Air Data

Inertial Reference and Acceleration

Flight control surface position

Aircraft systems status

Risk Mitigation

Conclusion

About the Author

https://www.DaedalusAero.Space/courses/fly-by-wire

The Fundamentals of Fly-By-Wire

Before we begin, let’s lay out some assumptions. This text assumes that the reader is an aviation professional, or at least very familiar with aircraft. It also assumes that the reader has already used, or had some exposure to, fly-by-wire (FBW) systems. Most importantly, this text assumes that the reader would like to better understand how fly-by-wire systems are structured – without digging into any math or engineering diagrams.

This document is generic to a variety of civil aircraft manufacturers, including Boeing, Airbus, Gulfstream, Dassault Falcon, Embraer, Bombardier, and others. The text will seek to avoid making direct references to any specific manufacturer’s system terminology, but the terms chosen may sound more familiar to some users. This is not intended to directly address military fighter or powered lift (multi-copter) design considerations, although many of the system