Khamsin Virtual Racecar challenge 2013 (CFD model racing)

[N12ck]

I've got a question regarding the parts that can be built. As I understand, there is no limit on the material thickness. For example someone could design parts with 1mm thickness which would be impossible in reality but will give probably some advantage on CFD testing, isn't it ?

Or is there an agreement that it is for example impossible to have parts under 3mm thickness ? How this issue is managed ?

I really hope I can have some time for this project, it looks really interesting.

We reserve the right to virtually ground a car if the design has been obviously altered to improve aerodynamic performances to the detriment of other performances not accounted for in the challenge.

I think this covers that one

[MadMatt]

It does, thank you !

[stez90]

What about internal and cockpit flows? Do we have to model the inside of the sidepots/cooling ducts with radiators (and maybe porous media for CFD) or will them stay closed (maybe with some strange boundary conditions)? Same thing for the inside of the cockpit and the driver (i think the presence of the driver and expecially his helmet will make a big difference in the aerodinamycs).

[julien.decharentenay]

You should have no problem exporting from Blender to Sketchup (free edition) - or from another CAD package. STL is likely to be the easiest format to use. To import STL in SketchUp you need the stl4su.rb plugin (available from sourceforge.net).

For the challenge we will take SketchUp file and aim to provide a plugin to SketchUp to guide you through simple test and model pre-arrangement. You do not need SketchUp Pro (but the Pro version would work fine as well).

Looks interesting! Waiting for updates..

A question for sketchup users: can i import a 3d model from Blender to Sketchup (free edition) and then save to the file format required from the challenge? Or will i need Sketchup Pro?

[julien.decharentenay]

The trial version can be used at each small release (30 days for v0.7 and 30 days for v0.8 ). We released v0.8 on the 31st July. If you have not trialled it, you can just plug in the same username and key and you should get another 30 days...

I've used my 30 day free trial up , I tried this a few months ago, now i need it i can't use it! lol

[machin]

that's a good point regarding the testing conditions.

So how does it work with regard to different tracks then?

I'm not sure I understand the question? How do we calculate lap-times for each track? Each track on Virtual Stopwatch has its own set of curvature and distance data. The program uses this data to determine the speed at each point on the track by calculating all the forces that are acting on the selected vehicle, and from there it determines the lap time. The special version for the championship replaces the F1 car model's aero data with an aeromap generated from the CFD test of each car.

This means, for instance, that a track like Monza will favour lower drag over higher downforce, and monaco favours high downforce over higher drag; just like the real laps. You can try a demonstration version of the standard F1 variant of Virtual Stopwatch online by following the link in my signature.

Does that answer your question?

[MadMatt]

I'm not sure I understand the question? How do we calculate lap-times for each track? Each track on Virtual Stopwatch has its own set of curvature and distance data. The program uses this data to determine the speed at each point on the track by calculating all the forces that are acting on the selected vehicle, and from there it determines the lap time. The special version for the championship replaces the F1 car model's aero data with an aeromap generated from the CFD test of each car.

This means, for instance, that a track like Monza will favour lower drag over higher downforce, and monaco favours high downforce over higher drag; just like the real laps. You can try a demonstration version of the standard F1 variant of Virtual Stopwatch online by following the link in my signature.

Does that answer your question?

Sorry if this is offtopic, but if you have taken part in this Virtual Stopwatch software, could you tell me more about its construction ? You say "all the forces that are acting on the selected vehicle", can you be more precise here ? I know these are not meant to be shared but it would be nice to know a bit more what's behind it. I have developed a software that also simulate a vehicle over a racetrack, and of course I also had to calculate forces, but I am wondering how different VS is compared to what I did !

[RicME85]

What about internal and cockpit flows? Do we have to model the inside of the sidepots/cooling ducts with radiators (and maybe porous media for CFD) or will them stay closed (maybe with some strange boundary conditions)? Same thing for the inside of the cockpit and the driver (i think the presence of the driver and expecially his helmet will make a big difference in the aerodinamycs).

It is stated that for the purpose of checking the area of intakes, the sidepods and vents need to be blanked.
Basic Gearbox, Engine etc are supplied.

[astracrazy]

Does that answer your question?

yes thanks. I was basically asking how does it work and how does it work with different tracks.

[machin]

Sorry if this is offtopic, but if you have taken part in this Virtual Stopwatch software, could you tell me more about its construction ?

No worries... this topic;

viewtopic.php?f=1&t=9280

...gives a fairly indepth description of the step by step process I employ for working out straight line acceleration... I haven't written a description for how the cornering works yet, but that is a plan for future Blog post on my site.

[MadMatt]

Sorry if this is offtopic, but if you have taken part in this Virtual Stopwatch software, could you tell me more about its construction ?

No worries... this topic;

viewtopic.php?f=1&t=9280

...gives a fairly indepth description of the step by step process I employ for working out straight line acceleration... I haven't written a description for how the cornering works yet, but that is a plan for future Blog post on my site.

Perfect, I'll read this when I get some time and when I can sit down relax !

[astracrazy]

what about doing a pre-season test, Feb time, so we can get an idea how our cars are performing before the first race? Even if its just at Spain

[machin]

what about doing a pre-season test, Feb time, so we can get an idea how our cars are performing before the first race? Even if its just at Spain

I think that sounds like a good idea as it'll allow you guys to "dial-in" your designs For the first race... I'll pass it on to the Khamsin guys (although I'm sure they've read this already).

Of course, we still have the end of season test in November first!

[N12ck]

what about doing a pre-season test, Feb time, so we can get an idea how our cars are performing before the first race? Even if its just at Spain

I think that sounds like a good idea as it'll allow you guys to "dial-in" your designs For the first race... I'll pass it on to the Khamsin guys (although I'm sure they've read this already).

Of course, we still have the end of season test in November first!

That is an interesting idea,

[astracrazy]

few more questions

will the test include drivers helmets?
what height will the cockpit opening be cut off at? top of the chassis?

looking forward to see nicks test so we can get an idea of the test run