Frequently Asked Questions.

Orbiter is a real-time 3D space flight simulator for the Windows PC. The concept is similar to traditional flight simulator software, but you are not limited to atmospheric flight. Orbiter allows you to experience manned and unmanned space flight missions from the pilot's perspective. Take control from launch to orbtial insertion, rendezvous with space stations, deploy and recapture satellites, and re-enter and land on a planetary surface. The playground is our solar system, and you can even execute missions to the moon or other planets. (Time compression is available to shorten long cruise phases.) Orbiter accurately models the physics of spaceflight, which makes it possible to either recreate historic missions, or use it as a sandbox for futuristic spacecraft concepts.

For more details on Orbiter, have a look at the mission statement, or the Orbiter Wikipedia entry.

The full Orbiter software can be downloaded from this site and is free for personal and non-commercial use. For details, see the Orbiter Freeware License terms. You can distribute Orbiter, but you are not allowed to charge a fee for it. If you paid for Orbiter (either on its own or as part of a compilation), you have probably been ripped off.

If you like Orbiter, you can show your appreciation by making a donation, but this is entirely voluntary.

If you want to use Orbiter in a context not covered by the freeware license terms, you must get written permission from the author.

Note that 3rd party Orbiter addons may be distributed under different licensing terms.

There is a web-based Orbiter message board where you can post general questions and suggestions. It has dedicated sections for bug reports, addon topics, and all things spaceflight.
Additional forum sites and orbiter-related pages can be found under the Forum page and the Links page. Another useful link for tutorials and developer resources is the OrbiterSimulator Wiki. For general information on Orbiter, see the Orbiter Wikipedia entry.
You can also join the ORBITER mailing list to exchange email with other users to get the latest hints and tricks.
Before submitting a bug report make sure you have the latest version, and that the problem is not already addressed in this FAQ or the forum.
As a last resort, you can email me directly, but I cannot guarantee that I will be able to answer all Orbiter posts.

I don't announce release dates and feature lists. This is mainly because Orbiter is a hobby of mine, and I don't need the pressure of working against a deadline or fixed specification. I can't always predict how much time I can spend on Orbiter, so the interval between releases will vary. The features added in a new version are usually a mixture of my own ideas and user requests.
Occasionally screen shots of the upcoming version will be posted on the Gallery page, just to keep the suspense up.

Remember you need only the "Base" and "Textures" packages to run Orbiter. Everything else is optional. Select a download mirror close to your location, and if necessary, try several (try to avoid the medphys server, because excessive demand on that server will get me into trouble ;)
If you have a slow connection, you may try at a different time of day when net traffic is lower. A download manager may help as well. Please note that I am not able to provide a CD distribution service, although Orbiter occasionally features on magazine cover discs (so this may be your last option).

If you want to create your own addons, you should download the Orbiter SDK (software development kit) package. This contains the libraries for compiling your own spacecraft code, sample code, a few utilities and documentation.
As a minimum, you will need to create a mesh for your spacecraft model (look at the Related Sites page for links to mesh converters from popular 3-D model formats such as 3ds), and define its basic physical properties in a configuration (.cfg) file. For more sophisticated models you may need to write and compile a specialised vessel plugin dll. Alternatively, there are 3rd party wrapper dlls available which can be controlled via configuration scripts.
Finally, you must design a scenario (.scn) which loads your new spacecraft to see it in action in Orbiter. It is probably easiest to modify an existing scenario file by replacing one of the vessel definitions.
If you get stuck, you may want to ask for help (or propose a collaborative project) on the addon forum.