Slipstream
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Slipstream is a free racing vehicle simulator trying to be physically accurate and fun to play at the same time! Contrary to most simulators out there it's not designed around a single type of vehicle. It should be able to support anything from a bicycle to a car or anything else that can be driven around on a racetrack for that matter.

Current status[top]

Although Slipstream is still in early development it should already be useful for a couple of purposes. A model of a modern motorcycle has been implemented and it handles well enough to be both fun and challenging to race around the available track. Besides that the vehicle model has been completely based on academic research (see the manual for details and references) and every care has been taken to make it as accurate as possible. Combine this with the fact that it is easily configurable, using either the graphic interface or scripting to the very last detail and you get a pretty good research tool.

May the 25th 2012: Second release

The second release brings much improved terrain shading as well as accurate off-road collision detection and response. Apart from that, the parameters of the tire model can be set separately for the track and the surrounding terrain paving the way for dirt tracks and off-road vehicles.

Get involved!

I could really use help developing Slipstream in a number of areas including:

One thing you should be aware of if you're thinking of participating in the development of Slipstream is that most of the positions above imply research assistant duty. Slipstream is based on Techne, which aspires to be a general-purpose simulator and renderer bringing computerized art to the masses, so while developing a GUI and better graphics for Slipstream is important, what's more important (at least for me) is developing the infrastructure that supports these in such a way that is generic and equally applicable to other projects besides Slipstream. I'm now in the process of redesigning Techne's renderer and http-based interface so I'm particularly in need of assistance from experienced artists and web designers for feedback in the design process. Please contact me via e-mail if you're interested in helping out with the development of Slipstream in some way.

Overview[top]

Pure multi-body simulation, no strings attached

One point of difference between Slipstream and every other motorcycle racing simulator I'm aware of is that it does not try to control the vehicle for you in any way. You can't just expect to press the left arrow key and magically balance the motorcycle at a 50 degree lean angle. Slipstream just simulates the actual machine piece for piece and allows you to use your mouse to apply pressure to the steering bars and control levers, the rest is up to you. This makes it a lot harder to learn how to control the vehicle but it also makes it a lot more fun by bringing out all the interesting effects most motorcycle riders are familiar with. Open the throttle too much when you're leaned over and the bike will drift, drop the front wheel without finesse after a wheelie and you'll get a tank-slapper, hit the brakes too hard and the bike starts weaving as the rear wheel loses traction.

Configurable to the last detail

Another unique point about Slipstream is that the vehicles are modeled piece for piece and are completely configurable. The current motorcycle model has been based on a couple of academic research papers that describe a particular 1000cc motorcycle so the default configuration reflects that. But that doesn't mean that only one motorcycle is available. The graphical interface allows the separate configuration of every parameter so that it's a matter of seconds to, for example, raise the steering head angle a few degrees, move the front wheel mount point further to the front and get a chopper-style motorcycle. Raise the rear spring stiffness to the point of rigidity as well and you get a hard-tail. Or you can leave everything as is and just move the rear wheel mount-point more to the back to get a long-swingarm drag-bike. You can probably make modifications that actually make the bike perform better as well. The possibilities are endless.

Education and research1

Apart from that, the fact that you can make modifications and try them out in real-time should make Slipstream ideal for anyone wanting to study the nature of motorcycle dynamics. It is easy for example to change the steering head rake or offset and see how this affects the handling. For the more academically-inclined it is also very easy to study the motorcycle by recording some parameter and then producing plots. For example it's easy to change to front chain sprocket position and see how this affects motorcycle squatting during acceleration by recording the extension of the rear damper rod during scripted acceleration runs before and after the modification.

I don't really know how well Slipstream would fare if applied to research as I'm not capable of assessing that. I've tried to produce plots of the models where I could and they seemed to match the published data and I have generally no reason to believe that Slipstream is less accurate than the setups used in the research papers. To be honest I have no reason to believe otherwise either but I would be very interested in finding out so if anyone's considering doing research with Slipstream let me know and I'll try to help out as much as I can. More information on the physics model can be found in the documentation.

Media[top]

Here are a couple of videos from the latest release.

Requirements[top]

Slipstream runs on Techne so you'll need a working installation of the latest version of Techne (version 0.2.3). Depending on the distribution you're using there might be packages available or you may need to compile the sources yourself. Head over to Techne's homepage to see the hardware and software requirements.

Downloads[top]

This is the second release of Slipstream, released on May the 25th 2012. In addition to these packages you'll also need to install Techne version 0.2.3 which you can find here.

Filename Size Description
slipstream-0.2.tar.gz 250K Source tarball
slipstream-data-0.2.tar.bz2 39M Data tarball
Debian/Ubuntu packages
slipstream_0.2-1_all.deb 85K Debian unstable/sid package
slipstream-data_0.2-1_amd64.deb 47M Debian unstable/sid (and Ubuntu Precise Pangolin) package
slipstream-data_0.2-1_i386.deb 47M Debian unstable/sid (and Ubuntu Precise Pangolin) package

The repository with all available versions can be found here.

Documentation[top]

Slipstream has a graphical interface that's mostly self-documenting and all vehicle control is carried out via the mouse so there's not much to running it. Configuring the vehicle models is more involved though so be sure to read the manual which is available both on-line as a single page http version and as a PDF document for off-line reading. The PDF version is recommended as it has readable formulas and is prettier overall.

Bugs[top]

Well Slipstream is relatively young so there is a remote possibility that some bugs exist. If you find one use the bugtracker in the project page to report it and I'll swiftly turn it into a feature.

Mailing Lists[top]

Discussion on the various matters concerning the internals and development of Slipstream can be carried out on the slipstream-devel mailing lists. Please use these instead of my personal e-mail address for matters that might potentially be of interest to other users as well. Also remember to use the support tracker if you're having trouble getting Slipstream to compile and run properly.

Author[top]

Slipstream was written by Dimitris Papavasiliou who anxiously awaits feedback including criticism, feature requests, bug reports and particularly offers to participate in the development. He can be reached at .

License[top]

Slipstream is released under the terms of the GNU General Public License.
The manual is distributed under the terms of the GNU Free Documentation License. See the appendix for details.