The Flight Gear Flight Simulator project is a free, open-source, multi-platform, cooperative flight sim development project. Source code for the entire project is available and licensed under the GPL. The Flight Gear project is working to create a sophisticated flight simulator framework for the development and pursuit of interesting flight simulator ideas. We are developing a good basic sim that can be expanded and improved upon by anyone interested in contributing.
FlightGear can be found at:
http://www.flightgear.org
http://www.flightgear.org/Downloads/binary.html
A few of the highlights of this release are:
* A flight "replay" system.
* More convenient ways to control the time of day.
* Many improvements to sky, cloud, scene, and aircraft lighting.
* Proper displaced thresholds added to runways that have them.
* Many new buildings and land marks added to the San Francisco area.
* Updated airports and navaids database (based on DAFIF and other sources.)
* Inclusion of a launcher that enables the user to select aircraft and starting location without needing to specify command line options.
* First stab at modeling helicopters with 3 initial designs to try.
* Several new aircraft and many improvements to existing aircraft.
* A complete rebuild of the world scenery based on SRTM terrain and VMAP roads, rivers, lakes, and land use.
For a complete list of changes, please visit:
http://www.flightgear.org/version.html
Erik Hofman

