Quote:
Originally Posted by tasdrouille
Phil, thanks for your input.
I'm surprised by the 5% max blockage as the A2 wind tunnel clearly is smaller than 200 square feet, yet they do testing for cars.
Anyway, even with the smallish 120 square feet tunnel I had in mind, 100kw ac engines apparengly go for more than $5k each. So it would turn out a bit expensive for a toy.
Cd, even if I was in the states I would certainly not pay for wind tunnel time. Their cousin tunnel, the AeroDyn wind tunnel, with pretty much the same dimensions charges $1590/hour.
I guess I'd be better off designing a camera rig that could be easily adapted between cars to film tufts testing.
Tufts are nice, but they don't tell you what the drag is with or without the aeromod you're testing.
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tasdrouille,some of the universities use a small plastic burrette as an underhood fuel tank when testing.If you can get reliable mpg figures from a prototype aeromod,you can use the delta-mpg as a back door to calculate your new Cd.If you test at a constant 55-MPH,any 2% drag reduction will yield a 1% increase in mpg.---------------------So say,you cobble up a mod out of cardboard and duct tape,test it at 55,and you get a 5% improvement at the gas pump,then you've cut your Cd by 10%,all else being equal.------------------------------ This is from SAE, and Glen Scharf at GM Aero Labs told me that it's a very accurate gauge in aero development.Something to think about and way cheaper than tunnel time!