Appendix B
Landing: some further thoughts before leaving the plane

B.1 A Sketch on the History of FlightGear

History may be a boring subject. However, from time to time there are people asking for the history of FlightGear. As a result, we’ll give a short outline.

The FlightGear project goes back to a discussion among a group of net citizens in 1996 resulting in a proposal written by David Murr who, unfortunately, dropped out of the project (as well as the net) later. The original proposal is still available and can be found under:

https://groups.google.com/g/rec.aviation.simulators/c/ny8HFBE5_T8/m/OdtIiGNGJc8J

Although the names of the people and several of the details have changed over time, the spirit of that proposal has clearly been retained up to the present time.

Actual coding started in the summer of 1996 and by the end of that year essential graphics routines were completed. At that time, programming was mainly performed and coordinated by Eric Korpela from Berkeley University. Early code ran under Linux as well as under DOS, OS/2, Windows 95/NT, and Sun-OS. This was found to be quite an ambitious project as it involved, among other things, writing all the graphics routines in a system-independent way entirely from scratch.

Development slowed and finally stopped in the beginning of 1997 when Eric was completing his thesis. At this point, the project seemed to be dead and traffic on the mailing list went down to nearly nothing.

It was Curt Olson from the University of Minnesota who re-launched the project in the middle of 1997. His idea was as simple as it was powerful: Why invent the wheel a second time? There have been several free flight simulators available running on workstations under different flavors of UNIX. One of these, LaRCsim (developed by Bruce Jackson from NASA), seemed to be well suited to the approach. Curt took this one apart and re-wrote several of the routines such as to make them build as well as run on the intended target platforms. The key idea in doing so was to exploit a system-independent graphics platform: OpenGL.

In addition, a clever decision on the selection of the basic scenery data was made in the very first version. FlightGear scenery is created based on satellite data published by the U.S. Geological Survey. These terrain data are available from:

https://www.usgs.gov/core-science-systems/ngp/tnm-delivery/gis-data-download

for the U.S., and

https://www.usgs.gov/centers/eros/science/usgs-eros-archive-digital-elevation-global-30-arc-second-elevation-gtopo30

resp., for other countries. Those freely accessible scenery data, in conjunction with scenery building tools included with FlightGear, are an important feature enabling anyone to create his or her own scenery.

This new FlightGear code – still largely being based on the original LaRCsim code – was released in July 1997. From that moment the project gained momentum again. Here are some milestones in the more recent development history.

B.1.1 Scenery

• Texture support was added by Curt Olson in spring 1998. This marked a significant improvement in terms of reality. Some high-quality textures were submitted by Eric Mitchell for the FlightGear project. Another set of high-quality textures was added by Erik Hofman ever since.
• After improving the scenery and texture support frame rate dropped down to a point where FlightGear became unflyable in spring 1998. This issue was resolved by exploiting hardware OpenGL support, which became available at that time, and implementing view frustum culling (a rendering technique that ignores the part of the scenery not visible in a scene), done by Curt Olson. With respect to frame rate one should keep in mind that the code, at present, is in no way optimized, which leaves room for further improvements.

• In September 1998 Curt Olson succeeded in creating a complete terrain model for the U.S. The scenery is available worldwide now, via a clickable map at:

  https://www.flightgear.org/download/scenery

• Scenery was further improved by adding geographic features including lakes, rivers, and coastlines later. Textured runways were added by Dave Cornish in spring 2001. Light textures add to the visual impression at night. To cope with the constant growth of scenery data, a binary scenery format was introduced in spring 2001. Runway lighting was introduced by Curt Olson in spring 2001. Finally, a completely new set of scenery files for the whole world was created by William Riley based on preparatory documentation by David Megginson in summer 2002. This is based on a data set called VMap0 as an alternative to the GSHHS data used so far. This scenery is a big improvement as it has world wide coverage of main streets, rivers, etc., while its downsides are much less accurate coast lines. FlightGear’s base scenery is based on these new scenery files since summer 2002.
• There was support added for static objects to the scenery in 2001, which permits placing buildings, static planes, trees and so on in the scenery.
• The world is populated with random ground objects with appropriate type and density for the local ground cover type since summer 2002. This marks a major improvement of reality and is mainly thanks to work by D. Megginson.
• Today, the effort is still going on, with the use of TerraSync, the tool for on-the-fly scenery download, the powerful mapserver and scenemodels infrastructure laying behind, as well as webforms enabling to quickly add or update objects. Scenery generation tools have been updated in order to use more accurate data such as the 8.50 apt.dat format, as well as external data such as OpenStreetMap, when the license is adequate.

B.1.2 Aircraft

• A HUD (Head-Up Display) was added based on code provided by Michele America and Charlie Hotchkiss in the fall of 1997 and was improved later by Norman Vine. While not generally available for real Cessna 172, the HUD conveniently reports the actual flight performance of the simulation and may be of further use in military jets later.
• A rudimentary autopilot implementing heading hold was contributed by Jeff Goeke-Smith in April 1998. It was improved by the addition of an altitude hold and a terrain following switch in October 1998 and further developed by Norman Vine later.
• Friedemann Reinhard developed early instrument panel code, which was added in June 1998. Unfortunately, development of that panel slowed down later. Finally, David Megginson decided to rebuild the panel code from scratch in January 2000. This led to a rapid addition of new instruments and features to the panel, resulting in nearly all main instruments being included until spring 2001. A handy minipanel was added in summer 2001.
• Finally, LaRCsims Navion was replaced as the default aircraft when the Cessna 172 was stable enough in February 2000 – a move most users will welcome. There are now several flight model and airplane options to choose from at runtime. Jon Berndt has invested a lot of time in a more realistic and versatile flight model with a more powerful aircraft configuration method. JSBSim, as it has come to be called, did replace LaRCsim as the default Flight Dynamics Model (FDM), and it is planned to include such features as fuel slosh effects, turbulence, complete flight control systems, and other features not often found all together in a flight simulator. As an alternative, Andy Ross added another flight dynamics model called YASim (Yet Another Flight Dynamics Simulator) which aims at simplicity of use and is based on fluid dynamics, by the end of 2001. This one bought us flight models for a 747, an A4, and a DC-3. Alternatively, a group around Michael Selig from the UIUC group provided another flight model along with several planes since around 2000.
• A fully operational radio stack and working radios were added to the panel by Curt Olson in spring 2000. A huge database of Navaids contributed by Robin Peel allows IFR navigation since then. There was basic ATC support added in fall 2001 by David Luff. This is not yet fully implemented, but displaying ATIS messages is already possible. A magneto switch with proper functions was added at the end of 2001 by John Check and David Megginson. Moreover, several panels were continually improved during 2001 and 2002 by John and others. FlightGear now allows flying ILS approaches and features a Bendix transponder.
• In 2002 functional multi-engine support found its way into FlightGear. JSBSim is now the default FDM in FlightGear.
• Support of “true” 3D panels became stable via contributions from John Check and others in spring 2002. In addition, we got movable control surfaces like propellers etc., thanks to David Megginson.

B.1.3 Environment

• The display of sun, moon and stars have been a weak point for PC flight simulators for a long time. It is one of the great achievements of FlightGear to include accurate modeling and display of sun, moon, and planets very early. The corresponding astronomy code was implemented in fall 1997 by Durk Talsma.
• Christian Mayer, together with Durk Talsma, contributed weather code in the winter of 1999. This included clouds, winds, and even thunderstorms.

B.1.4 User Interface

• The foundation for a menu system was laid based on another library, the Portable Library PLIB, in June 1998. After having been idle for a time, the first working menu entries came to life in spring 1999.

  PLIB underwent rapid development later. It has been distributed as a separate package by Steve Baker with a much broader range of applications in mind, since spring 1999. It has provided the basic graphics rendering engine for FlightGear since fall 1999.

• In 1998 there was basic audio support, i. eȧn audio library and some basic background engine sound. This was later integrated into the above-mentioned portable library, PLIB. This same library was extended to support joystick/yoke/rudder in October 1999, again marking a huge step in terms of realism. To adapt on different joystick, configuration options were introduced in fall 2000. Joystick support was further improved by adding a self detection feature based on xml joystick files, by David Megginson in summer 2002.
• Networking/multiplayer code has been integrated by Oliver Delise and Curt Olson starting fall 1999. This effort is aimed at enabling FlightGear to run concurrently on several machines over a network, either an Intranet or the Internet, coupling it to a flight planner running on a second machine, and more. There emerged several approaches for remotely controlling FlightGear over a Network during 2001. Notably there was added support for the “Atlas” moving map program. Besides, an embedded HTTP server developed by Curt Olson late in 2001 can now act a property manager for external programs.
• Manually changing views in a flight simulator is in a sense always “unreal” but nonetheless required in certain situations. A possible solution was supplied by Norman Vine in the winter of 1999 by implementing code for changing views using the mouse. Alternatively, you can use a hat switch for this purpose, today.
• A property manager was implemented by David Megginson in fall 2000. It allows parsing a file called .fgfsrc for input options. This plain ASCII file has proven useful in submitting the growing number of input options, and notably the joystick settings. This has shown to be a useful concept, and joystick, keyboard, and panel settings are no longer hard coded but set using *.xml files since spring 2001 thanks to work mainly by David Megginson and John Check.

During development there were several code reorganization efforts. Various code subsystems were moved into packages. As a result, code is organized as follows at present:

The base of the graphics engine is OpenGL, a platform independent graphics library. Based on OpenGL, the Portable Library PLIB provides basic rendering, audio, joystick etcṙoutines. Based on PLIB is SimGear, which includes all of the basic routines required for the flight simulator as well as for building scenery. On top of SimGear there are (i) FlightGear (the simulator itself), and (ii) TerraGear, which comprises the scenery building tools.

This is by no means an exhaustive history and most likely some people who have made important contributions have been left out. Besides the above-named contributions there was a lot of work done concerning the internal structure by: Jon S. Berndt, Oliver Delise, Christian Mayer, Curt Olson, Tony Peden, Gary R. Van Sickle, Norman Vine, and others. A more comprehensive list of contributors can be found in Chapter A.4 as well as in the Thanks file provided with the code. Also, the FlightGear Wiki contains a detailed history worth reading of all of the notable development milestones at

https://wiki.flightgear.org/Category:FlightGear_changelogs

B.2 Those, who did the work

Did you enjoy the flight? In case you did, don’t forget those who devoted hundreds of hours to that project. All of this work is done on a voluntary basis within spare time, thus please bear with the programmers in case something does not work the way you want it to. Instead, sit down and write them a kind (!) mail proposing what to change. Alternatively, you can subscribe to the FlightGear mailing lists and contribute your thoughts there. Instructions to do so can be found at

https://wiki.flightgear.org/Mailing_lists

Essentially, there are two lists: one of which being mainly for the developers and the other one for end users. Besides, there is a very low-traffic list for announcements.

The following names the people who did the job (this information was essentially taken from the Thanks file accompanying the code).

A1 Free Sounds

Granted permission for the FlightGear project to use some of the sound effects from their site.

Syd Adams

Added clipping for 2D instruments, ATC volume control and created a wide variety of aircraft.

Raul Alonzo

Mr. Alonzo is the author of Ssystem and provided his kind permission for using the moon texture. Parts of his code were used as a template when adding the texture. Ssystem Homepage can be found at:

http://openuniverse.sourceforge.net

Michele America

Contributed to the HUD code.

Michael Basler

Author of Installation and Getting Started. Flight Simulation Page at:

https://www.flusi.info

Jon S. Berndt

Working on a complete C++ rewrite/reimplimentation of the core FDM. Initially he is using X15 data to test his code, but once things are all in place we should be able to simulate arbitrary aircraft. Jon maintains a page dealing with Flight Dynamics at:

http://jsbsim.sourceforge.net

Special attention to X15 is paid in separate pages on this site. Besides, Jon contributed via a lot of suggestions/corrections to this Guide.

Paul Bleisch

Redid the debug system so that it would be much more flexible, so it could be easily disabled for production system, and so that messages for certain subsystems could be selectively enabled. Also contributed a first stab at a config file/command line parsing system.

Jim Brennan

Provided a big chunk of online space to store USA scenery for FlightGear!

Bernie Bright

Many C++ style, usage, and implementation improvements, STL portability and much, much more. Added threading support and a threaded tile pager.

Stuart Buchanan

Updated various parts of the manual, wrote the initial tutorial subsystem, developed random vegetation and buildings.

Bernhard H. Buckel

Contributed the README.Linux. Contributed several sections to earlier versions of Installation and Getting Started.

Gene Buckle

A lot of work getting FlightGear to compile with the MSVC++ compiler. Numerous hints on detailed improvements.

Ralph Carmichael

Support of the project. The Public Domain Aeronautical Software web site at

https://www.pdas.com/

has the PDAS CD-ROM for sale containing great programs for astronautical engineers.

Didier Chauveau

Provided some initial code to parse the 30 arcsec DEM files found at:

https://www.usgs.gov/centers/eros/science/usgs-eros-archive-digital-elevation-global-30-arc-second-elevation-gtopo30.

John Check

John maintains the base package CVS repository. He contributed cloud textures, wrote an excellent Joystick Howto as well as a panel Howto. Moreover, he contributed new instrument panel configurations.

Dave Cornish

Dave created new cool runway textures plus some of our cloud textures.

Oliver Delise

Started a FAQ, Documentation, Public relations. Working on adding some networking/multi-user code. Founder of the FlightGear MultiPilot.

Jean-Francois Doue

Vector 2D, 3D, 4D and Matrix 3D and 4D inlined C++ classes. (Based on Graphics Gems IV, Ed. Paul S. Heckbert)

https://www.animats.com/simpleppp/ftp/public_html/topics/developers.html

Dave Eberly

Contributed some sphere interpolation code used by Christian Mayer’s weather data base system.

Francine Evans

Wrote the GPL’d tri-striper we use:

https://www3.cs.stonybrook.edu/~stripe/

Oscar Everitt

Created single engine piston engine sounds as part of an F4U package for FS98. They are pretty cool and Oscar was happy to contribute them to our little project.

Bruce Finney

Contributed patches for MSVC5 compatibility.

Olaf Flebbe

Improved the build system for Windows and provided pre-built dependencies.

Melchior Franz

Contributed joystick hat support, a LED font, improvements of the telnet and the HTTP interface. Notable effort in hunting memory leaks in FlightGear, SimGear, and JSBSim.

Jean-loup Gailly and Mark Adler

Authors of the zlib library. Used for on-the-fly compression and decompression routines:

https://zlib.net.

Mohit Garg

Contributed to the manual.

Thomas Gellekum

Changes and updates for compiling on FreeBSD.

Neetha Girish

Contributed the changes for the XML-configurable HUD.

Jeff Goeke-Smith

Contributed our first autopilot (Heading Hold). Better autoconf check for external timezone and daylight variables.

Michael I. Gold

Patiently answered questions on OpenGL.

Habibe

Made RedHat package building changes for SimGear.

Mike Hill

For allowing us to concert and use his wonderful planes for FlightGear.

Erik Hofman

Major overhaul and parameterization of the sound module to allow aircraft-specific sound configuration at runtime. Contributed SGI IRIX support (including binaries) and some really great textures.

Charlie Hotchkiss

Worked on improving and enhancing the HUD code. Lots of code style tips and code tweaks.

Bruce Jackson (NASA)

Developed the LaRCsim code under funding by NASA which we use to provide the flight model. Bruce has patiently answered many, many questions.

Maik Justus

Added helicopter support, gear/ground interaction and aerotow/winch support to the YASim FDM.

Ove Kaaven

Contributed the Debian binary.

Richard Kaszeta

Contributed screen buffer to ppm screen shot routine. Also helped in the early development of the “altitude hold autopilot module” by teaching Curt Olson the basics of Control Theory and helping him code and debug early versions. Curt’s “Boss” Bob Hain also contributed to that. Further details available in “Flight Gear Autopilot: Altitude Hold Module” on archive.org.¹

Rich’s Homepage is at

http://www.kaszeta.org/rich/

Tom Knienieder

Ported the audio library first to OpenBSD and IRIX and after that to Win32.

Reto Koradi

Helped with setting up fog effects.

Bob Kuehne

Redid the Makefile system so it is simpler and more robust.

Kyler B Laird

Contributed corrections to the manual.

Roman Ludwicki

Contributed corrections and the Polish translation of this manual, refreshed all screenshots using a current version of FlightGear (in 2021), improved or remade other illustrations (e.g., using vector formats), and helped to get the LaTeX markup of this manual cleaner.

David Luff

Contributed heavily to the IO360 piston engine model.

Sam van der Mac

Contributed to the manual by translating HTML tutorials to LaTeX.

Christian Mayer

Working on multi-lingual conversion tools for fgfs as a demonstration of technology. Contributed code to read Microsoft Flight Simulator scenery textures. Christian is working on a completely new weather subsystem. Donated a hot air balloon to the project.

David Megginson

Contributed patches to allow mouse input to control view direction yoke. Contributed financially towards hard drive space for use by the FlightGear project. Updates to README.running. Working on getting fgfs and ssg to work without textures. Also added the new 2D panel and the save/load support. Further, he developed new panel code, playing better with OpenGL, with new features. Developed the property manager and contributed to joystick support. Random ground cover objects.

Cameron Moore

FAQ maintainer. Reigning list administrator. Provided man pages.

Eric Mitchell

Contributed some topnotch scenery textures being all original creations by him.

Anders Morken

Former maintainer of European web pages.

Alan Murta

Created the Generic Polygon Clipping library.

https://en.wikipedia.org/wiki/General_Polygon_Clipper

Phil Nelson

Author of GNU dbm, a set of database routines that use extendible hashing and work similar to the standard UNIX dbm routines.

Alexei Novikov

Created European Scenery. Contributed a script to turn fgfs scenery into beautifully rendered 2D maps. Wrote a first draft of a Scenery Creation Howto.

Curt Olson

Primary organization of the project.
First implementation and modifications based on LaRCsim.
Besides putting together all the pieces provided by others mainly concentrating on the scenery subsystem as well as the graphics stuff.

Brian Paul

We made use of his TR library and of course of Mesa:

https://www.ssec.wisc.edu/~billh/bp/TR.html,
https://www.mesa3d.org

Tony Peden

Contributions on flight model development, including a LaRCsim based Cessna 172. Contributed to JSBSim the initial conditions code, a more complete standard atmosphere model, and other bugfixes/additions.

Robin Peel

Maintains worldwide airport and runway database for FlightGear as well as X-Plane.

Alex Perry

Contributed code to more accurately model VSI, DG, Altitude. Suggestions for improvements of the layout of the simulator on the mailing list and help on documentation.

Friedemann Reinhard

Development of an early textured instrument panel.

Petter Reinholdtsen

Incorporated the GNU automake/autoconf system (with libtool). This should streamline and standardize the build process for all UNIX-like platforms. It should have little effect on IDE type environments since they don’t use the UNIX make system.

William Riley

Contributed code to add “brakes”. Also wrote a patch to support a first joystick with more than 2 axes. Did the job to create scenery based on VMap0 data.

Andy Ross

Contributed a new configurable FDM called YASim (Yet Another Flight Dynamics Simulator), based on geometry information rather than aerodynamic coefficients.

Paul Schlyter

Provided Durk Talsma with all the information he needed to write the astro code. Mr. Schlyter is also willing to answer astro-related questions whenever one needs to.

https://stjarnhimlen.se/english.php

Chris Schoeneman

Contributed ideas on audio support.

Phil Schubert

Contributed various textures and engine modeling.

Jonathan R. Shewchuk

Author of the Triangle program. Triangle is used to calculate the Delaunay triangulation of our irregular terrain.

Gordan Sikic

Contributed a Cherokee flight model for LaRCsim. Currently is not working and needs to be debugged. Use --fdm=larcsim --aero=cherokee options to run the Cherokee instead of the Cessna.

Michael Smith

Contributed cockpit graphics, 3D models, logos, and other images. Project Bonanza.

Martin Spott

Co-Author of The Manual.

Jon Stockill

Maintains a database of objects and their location to populate the worldwide scenery.

Durk Talsma

Accurate Sun, Moon, and Planets. Sun changes color based on position in sky. Moon has correct phase and blends well into the sky. Planets are correctly positioned and have proper magnitude. Help with time functions, GUI, and other things. Contributed 2D cloud layer. Website at

http://www.durktalsma.nl.

UIUC – Department of Aeronautical and Astronautical Engineering

Contributed modifications to LaRCsim to allow loading of aircraft parameters from a file. These modifications were made as part of an icing research project.

Those did the coding and made it all work:
Jeff Scott
Bipin Sehgal
Michael Selig

Moreover, those helped to support the effort:
Jay Thomas
Eunice Lee
Elizabeth Rendon
Sudhi Uppuluri

U.S. Geological Survey

Provided geographic data used by this project.

https://www.usgs.gov/core-science-systems/ngp/tnm-delivery/gis-data-download

Mark Vallevand

Contributed some METAR parsing code and some Win32 screen printing routines.

Gary R. Van Sickle

Contributed some initial GameGLUT support and other fixes. Has done preliminary work on a binary file format.

Norman Vine

Provided numerous URLs to the FlightGear community. Many performance optimizations throughout the code. Many contributions and much advice for the scenery generation section. Lots of Windows related contributions. Contributed wgs84 distance and course routines. Contributed a great circle route autopilot mode based on wgs84 routines. Many other GUI, HUD and autopilot contributions. Patch to allow mouse input to control view direction. Ultra hires tiled screen dumps. Contributed the initial goto airport and reset functions and the initial HTTP image server code.

Roland Voegtli

Contributed great photorealistic textures. Founder of European Scenery Project for X-Plane.

Carmelo Volpe

Porting FlightGear to the Metro Works development environment (PC/Mac).

Darrell Walisser

Contributed a large number of changes to porting FlightGear to the Metro Works development environment (PC/Mac). Finally produced the first Macintosh port. Contributed to the Mac part of Getting Started, too.

Ed Williams

Contributed magnetic variation code (implements Nima WMM 2000). We’ve also borrowed from Ed’s wonderful aviation formulary at various times as well. Website at:

https://edwilliams.org

Jim Wilson

Wrote a major overhaul of the viewer code to make it more flexible and modular. Contributed many small fixes and bug reports. Contributed to the PUI property browser and to the autopilot.

Jean-Claude Wippler

Author of MetaKit – a portable, embeddible database with a portable data file format previously used in FlightGear. Please see the following URL for more info:

https://www.equi4.com/metakit/

Woodsoup Project

While FlightGear no longer uses Woodsoup services we appreciate the support provided to our project during the time they hosted us. Once upon a time, they provided computing resources and services so that the FlightGear project could have a real home.

Robert Allan Zeh

Helped tremendously in figuring out the Cygnus Win32 compiler and how to link with .dll’s. Without him, the first run-able Win32 version of FlightGear would have been impossible.

Pablo Barrio and Gonzalo Pesquero

Contributed to the Spanish translation of the manual and the FlightGear GUI.

Others

The following individuals have contributed to the scenery object database: Jon Stockill, Martin Spott, Dave Martin, Thomas Foerster, Chris Metzler, Frédéric Bouvier, Melchior Franz, Roberto Inzerillo, Erik Hofman, Mike Round, Innis Cunningham, David Megginson, Stuart Buchanan, Josh Babcock, Esa Hyytia, Mircea Lutic, Jens Thoms Toerring, Mark Akermann, Torsten Dreyer, Martin C. Doege, Alexis Bory, Sebastian Bechtold, Julien Pierru, Bertrand Augras, Gerard Robin, Jakub Skibinski, Morten Oesterlund Joergensen, Carsten Vogel, Dominique Lemesre, Daniel Leygnat, Bertrand Gilot, Morten Skyt Eriksen, Alex Bamesreiter, Oliver Predelli, Georg Vollnhals, and Paul Richter.

B.3 What remains to be done

If you read (and, maybe, followed) this guide up to this point you may probably agree: FlightGear even in its present state, is not at all for the birds. It is already a flight simulator that supports even several flight models, many planes with 3D cockpits, HUD, terrain scenery with realistic buildings, roads, rivers, water awkens, all basic controls with many joysticks support and real weather.

Despite, FlightGear needs – and gets – further development. Except internal tweaks, there are several fields where FlightGear needs basics improvement and development. A first direction is adding airports, buildings, and more of those things bringing scenery to real life and belonging to realistic airports and cities. Another task is further implementation of the menu system, which should not be too hard with the basics being working now. A lot of options at present set via command line or even during compile time should finally make it into menu entries. Finally, FlightGear doesn’t have a good ATC so far.

There are already people working in all of these directions. If you’re a programmer and think you can contribute, you are invited to do so.

Acknowledgements

Obviously this document could not have been written without all of the contributors mentioned above for making FlightGear a reality.

First, I was very glad to see Martin Spott entering the documentation effort. Martin provided not only several updates and contributions (notably in the OpenGL section) on the Linux side of the project but also several general ideas on the documentation in general.

I would like to express a special thanks to Curt Olson, whose numerous scattered READMEs, Thanks, Webpages, and personal emails were of special help to me and were freely exploited in the making of this booklet.

Next, Bernhard Buckel wrote several sections of early versions of that Guide and contributed at lot of ideas to it.

Jon S. Berndt supported me by critical proofreading of several versions of the document, pointing out inconsistences and suggesting improvements.

Moreover, I gained a lot of help and support from Norman Vine. Maybe, without Norman’s answers I would have never been able to tame different versions of the Cygwin – FlightGear couple.

We were glad, our Mac expert Darrell Walisser contributed the section on compiling under macOS. In addition, he submitted several Mac-related hints and fixes.

Further contributions and donations on special points came from John Check, (general layout), Oliver Delise (several suggestions including notes on that chapter), Mohit Garg (OpenGL), Kyler B. Laird (corrections), Alex Perry (OpenGL), Kai Troester (compile problems), Dave Perry (joystick support), and Michael Selig (UIUC models).

Besides those whose names got lost withing the last-minute-trouble we’d like to express our gratitude to the following people for contributing valuable “bug fixes” to this version of The FlightGear Manual (in random order): Cameron Moore, Melchior Franz, David Megginson, Jon Berndt, Alex Perry, Dave Perry, Andy Ross, Erik Hofman, and Julian Foad.