Sunday, August 5, 2012

CO2 Car Body Design

After I picked up the CO2 car kit from the scout shop I started work on the design of the body. I use Alibre CAD here at home and for consulting work. It is proficient for most mechanical CAD work I do, but I have not been impressed by it's surfacing capability. But hey nothing in in my home use budget is going to compare to software like Unigraphics NX (read >$30,000).

So I whipped up a few lofted and swept profiles and created this model. 

Co2 Car body Design

 I ran the simulation in Project Falcon creating these results:
The car as a coefficient of friction of .34 and a drag force of .17 newtons a 60 mph. The coefficient of drag is not really all that great, but it is difficult to get much better because the hole where the Co2 cartridge goes creates a large low pressure zone with lots of eddy current (seen as the blue traces in the picture). The .17 newtons of drag is the best result I came up with out of all the preliminary designs I did. So I'm fairly confident this is a near optimum shape.

But What about mass? isn't that the most important parameter? Well if you look at the bottom of the car, you will notices that behind the front wheels the main portion of the body is hollow. I didn't spend as much time reducing weigh as possible, but I didn't do any stress analysis to determine how thin I could go, so the design is a bit sub par in that aspect.

However the point is that this is for fun, and I'm having fun with it up to this point.

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