Quote:
Originally Posted by tasdrouille
So, I've been reading a bit about wind tunnels lately, secretly dreaming of someday building my own.
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Keep dreaming, good ones are huge and expensive.
For a full scale wind tunnel your only real option is called "the road". With two cars (test and chase) you can do tuft testing. With three (add a smoke generator on a lead car) you can do a bit more. Plus, and unlike in any but the most expensive wind tunnels, the wheels are turning, which does affect the aerodynamics. Measuring forces is difficult. I think though, that if you towed the test car on a long enough cable (to get it out of the tow car's wake) it should be possible to deduce drag by measuring the tension on that cable at a fixed test speed. Proximity to an abandoned landing strip or dry lake bed would also be a big plus.
Another option, if you can afford it, is to rent one of those car carrier trucks which has a flat bed that extends over the entire length of the truck. You know, when end is over the cab, and the back tilts down to load and unload the car. With a big stable platform like that it would be easy to put a smoke generator up at the front, and to mount cameras at fixed positions.
If you want to work at 1/24th scale the road is again your best bet. Build an open tube and mount it on the roof of a car. Direct measurement of forces becomes possible, although to get good accuracy you are going to need accelerometers on all 3 axes on both the test model and the car carrying it - and a good flat road.