FlightGear

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FlightGear
FlightGear logo
Wright Flyer in 0.9.9
Wright Flyer in 0.9.9
Developed by FlightGear Developers & Contributors
Initial release July 17, 1997
Written in C++
OS 32-bit Windows, Linux, Mac OS X, FreeBSD, Solaris or IRIX
Platform Cross-platform
Development status Active (1996-)
Type Flight simulator
License GNU General Public License
Website
NASA OV-10 in FlightGear 1.0

FlightGear Flight Simulator (often shortened to FlightGear or FGFS) is a sophisticated free, completely open-source flight simulator framework, created by volunteers.

The project was started back in 1996, with the first release in 1997. The latest public release is 1.9.0 in December 2008, with specific builds for a variety of operating systems including Microsoft Windows (Win 32), Mac OS X, Linux, IRIX, and Solaris.

FlightGear is released under the terms of the GNU General Public License. Flightgear is mostly written in C++ with some in C programming languages.

History

Beginnings (1996-1997)

Development formally started in the late-1990s with an online proposal and code being written in 1996, but using custom 3D graphics code. Development of an OpenGL based version was spearheaded by Curtis Olsen starting in 1997, after the initial start in 1996. A large community response lead to many contributing to the project from its start in late '90s up to the present.

Rather than start entirely from scratch, FlightGear developers made use of the LaRCsim flight model from NASA, with OpenGL for 3D graphic code, and freely available elevation data. First working binaries came out in 1997, with an intense updating of newer versions for several years resulting in progressively more stable and advanced programs.

Versions 0.7–0.9 (2001–2003)

By 2001, the team was releasing new beta versions regularly (0.7.x, 0.8.0, over 2001-2003) and with 0.9.xx(2003-2006). Later in the decade, the rate of final public releases slowed, but had larger amounts of content (0.9.10, 1.0.0 etc.). The maturity of software by 2005 lead to more widespread reviews, and increased popularity. The use of version numbers slowed dramatically after the late 2002 release of version 0.9.0. Versions 0.9.9 (2005) and 0.9.10 (2006) had about 8 all-new or redone aircraft adding to a total of 70-90 aircraft, while 0.9.11-pre1 had about 33 new or redone designs and 1.9.0 launched with up to 230 aircraft although with varying degrees of compatibility.

Version 0.9.0-1.0 (2002-2007)

3D Cockpit panel for A-10 in version 1.0.0 in 2008

Nearly the whole world is well represented using the freely available SRTM elevation data, and a number of special features are available, such as sloped runways. Over 20,000 runways, 3D clouds, multi-platform support, multiple open FDM choices, roughly 100 aircraft choices by version 0.9.10 provide a well-rounded feature set.

Hardware needed for FlightGear is narrow to machines that support OpenGL and 3D hardware acceleration, with NVIDIA hardware having better support. Early versions had support for 3dfx cards, though this dropped as hardware requirements increased.

FlightGear has been used in a range of projects in academia and industry.

Version 1.9.0 (2008)

At the time version 1.9.0 was released FlightGear switched from PLIB to OSG, which caused the temporarily lost of some of the features like 3D clouds and shadows. Most aircraft developed for OSG do not work with older versions. The users is able to choose out of 230 aircraft provided with 1.9.0, altough only a few are included in the base package.

Release timeline

Final build code release dates by year.

Date Version
July 17, 1997 First major code release
September 23, 1997 0.12
December 9, 1997 0.15
December 17, 1997 0.18
December 30, 1997 0.19 (first binaries)
January 6, 1998 0.22
Mar 11 98 0.37
April 8, 1998 0.41
April 14, 1998 0.42
April 23, 1998 0.43
Apr 28, 1998 0.44
May 7, 1998 0.45
May 11, 1998 0.46
May 18, 1998 0.47
June 9, 1998 0.48
June 27, 1998 0.49
July 13, 1998 0.50
July 21, 1998 0.51
August 15, 1998 0.52
September 2, 1998 0.53
September 25, 1998 0.54
October 23, 1998 0.55
November 23, 1998 0.56
January 21, 1999 0.57
February 10, 1999 0.58
March 31, 1999 0.59
May 26, 1999 0.6.0
Date Version
June 21, 1999 0.6.1 (Stable)
September 11, 1999 0.7.0 (Development)
0.6.2 (Stable)
October 22, 1999 0.7.1 (Development)
February 17, 2000 0.7.2 (Development)
May 18, 2000 0.7.3 (Development)
July 20, 2000 0.7.4
September 18, 2000 0.7.5
Decemberember 19, 2000 0.7.6
June 20, 2001 0.7.7
July 13, 2001 0.7.8
February 16, 2002 0.7.9
April 20, 2002 0.7.10
September 7, 2002 0.8.0
December 3, 2002 0.9.0
December 5, 2002 0.9.1
June 4, 2003 0.9.2
October 24, 2003 0.9.3
March 26, 2004 0.9.4
July 29, 2004 0.9.5
October 12, 2004 0.9.6
January 18, 2005 0.9.8
November 17, 2005 0.9.9
April 5, 2006 0.9.10
May 2007 0.9.11-pre1
December 17, 2007 1.0.0
December 22, 2008 1.9.0 (latest final build)

Software

The simulation engine in FlightGear is called SimGear. It is used both as an end-user application and in academic and research environments, for the development and pursuit of flight simulation ideas.

This customizability of FlightGear is illustrated by the wide range of aircraft models that are available in FlightGear, from gliders to Helicopters, and from airliners to fighter jets. These aircraft models have been contributed by many different people.

The FlightGear aircraft use one of three main data models JSBSim, YAsim, or UIUC as of version 0.9.10. Currently only one terrain engine is used, TerraGear. Weather effects include 3D clouds, lighting effects, and time of day.

Flight Dynamics Models

Flight Dynamics Models (FDM) are how the flight for an aircraft is simulated in the program. FlightGear uses a variety of internally written and imported flight model projects. Any aircraft must be programmed to use one of these models. Currently FlightGear is the only flight graphical flight simulator all the FDM are used for, and UIUC and YASim were developed specifically for FlightGear.

Early version used a FDM based on LaRCsim by NASA, which was replaced with more flexible FDM.

  • JSBSim - the default flight dynamics model software since 2000.
  • YASim - another FDM using different calculation method. Introduced starting in 0.7.9 in 2002.
  • UIUC - another included FDM, developed by the UIUC Applied Aerodynamics Group at University of Illinois at Urbana-Champaign, also made use of LaRCsim.
  • Flight Gear can also be setup to render using inputs from an external FDM source, such as from Matlab.
  • Other custom FDM for a specific aircraft type have been written, such as for lighter than air aircraft.

FlightGear dependencies

Unlike commercial software titles, the main output of the project is simply the release of a collection of code. To turn it into a usable program it must be compiled for a given platform. The software libraries used to create FlightGear have varied over time. The main one is SimGear, which is the underlying sim engine for FlightGear. TerraGear is not a dependency, but simply a name for the default terrain data program in FlightGear. OpenAL is used for sound/audio software, including support for SDL (since 0.9.5). PLIB is used for hardware support routines, formerly used for sound support also which was taken over by OpenAL. OpenGL is used for its integrated 3D graphics routines, and other hardware acceleration (namely DirectX) is not supported. OpenSceneGraph is also integrated into FlightGear. Finally, Simple DirectMedia Layer is a software library which is used for compiling. Some of the dependencies vary depending on which platform the code is being compiled for. FlightGear users must either compile the code themselves, or find a third party to release a binary, if it is not among the ones available from the project.

Add-ons and customization

There are programs that are either integrated into FlightGear (dependencies) or perform a function with it. Some of these are included in the release of FlightGear for a specific platform but made by the project, while others are independently distributed but are hosted by the FlightGear project.

One major additional software is the actual interface for launching an executable of FlightGear. For most of its early life FlightGear was only run through command line interfaces. However, the FlightGear Launch Control has been included with the FG launcher front-end since 0.9.3 in 2003. KFreeFlight is a launcher/front-end for KDE. FGTools is an alternative windows launcher front-end. FGKicker is a GTK+ based front-end.

Other significant programs include editors and projects for Terrain Data. Atlas is a chart/map support for FlightGear; Kelpie Flight Planner is a Java based flight planner for FlightGear. FlightGear Scenery Designer is a FlightGear scenery editor for working with terrain data. The World Custom Scenery Project is a project coordinating custom scenery efforts. Finally, TaxiDraw is an editor for airport runways and taxiways.

Aircraft

1rightarrow.png See Table of models for the main article about this subject.

FlightGear started out with an aircraft included in NASA's LaRCsim, a Navion, which was replaced by a Cessna 172 by 2000. UIUC as well as JSBsim development brought several more aircraft with them, as did the development of YASim which have since become the main FDM used in FG. As of version 1.9.0 an amount of more than 230 aircraft is provided.

Boeing 733 docked in the EHAM scenery

Scenery

1rightarrow.png See Scenery for the main article about this subject.

FlightGears world scenery project contains elevation and landclass data of the enitre world. Objects -like terminals, windmills and bridges- are collected in the Scenery Database.

Networking and multi-display

Several networking options allow FlightGear to communicate with other instances of FlightGear. A multiplayer protocol is available for using FlightGear on a local network in a multi aircraft environment. This could be used for formation flight or control tower simulation. Multiplayer was soon expanded to allow playing over the internet. Other features include a Google maps based moving up that allows users to observe where other players are.

Several instances of FlightGear can be synchronized to allow for a multi-monitor environment. If all instances are running at the same frame rate consistently, it is possible to get good and tight synchronization between displays.

FlightGear code vs. binaries

Unlike most commercial software, the project release dates only apply to a release of code, not an executable program. To create a runnable program the code must be compiled, which requires several specific libraries, including some general ones and, in some cases some platform specific ones. However, since this too difficult for most mainstream users, other contributors will work to make binaries available for a specific platform and operating system. These packages vary in their stability, performance, dependencies, and how up to date they are with the code base. For example, some older binaries work on Mac OS 9 but newer releases require specific Mac OS X versions.

For example, by late 2007 the latest code release was 0.9.11-pre1 (pre-release) and 0.9.10 (final). However, the actual binaries available vary significantly. Examples of actual binaries available a year after the release of the 0.9.10 code release:

  • Win-32 has ~138 Mb package (v0.9.10) (For Windows 98, 2000, ME, 32-bit XP)
  • Linux- pre-built packages for specific Linux distributions
    • Slackware package (v0.9.10), Fedora Core 2,3,4 packages (v0.9.10), Pardus (v0.9.10), Debian (v0.9.9)
  • Solaris packages either for it running on either SPARC or x86 processors.
    • SPARC (v0.9.8), x86 (v0.9.9)
  • Silicon Graphics IRIX
    • SGI binaries for (v0.9.9)
  • Mac OS X
    • Mac OS 10.4 (v0.9.10)
    • Mac OS 10.3 (v0.9.9)
  • FreeBSD has a package for(v0.9.10)

FlightGear reviews

1rightarrow.png See FlightGear Reviews for the main article about this subject.

External links

Sources