Where's the best place to test aero? How about a tunnel?

[niky]

The secret racing test tunnel no one wants to talk about

"I'd been in the car for, like, seven hours, bored senseless," he said, "and not really expecting a crash. Then all of a sudden, the ****ing car's doing an S-bend at 140 mph and I started climbing the wall."

A one mile long abandoned tunnel. A testing environment most of us can only dream of...

[ChazInMT]

Ummmm. The guys at Synergy Aircraft eschew wind tunnels because they invariably interfere with the actual results that happen in free air. For an airplane, it's a huge deal. For a car, it may not be as significant, but still far from a "dream set-up", unless you want to drive in tunnels all the time, in which case, this is awesome.

[Frank Lee]

I wonder how the limited cross-sectional area of the tunnel impacts the testing? Probably no worse or no better than wind tunnel testing.

The tunnel tunnel testing looks like a good idea to me if one wants to eliminate winds from any direction from the tests, use the actual vehicle instead of a model, and doesn't have a fortune for wind tunnel time.

Aircraft don't have to worry about yaw forces/effects unless they're interfacing or about to interface with the ground.

[niky]

I'd think if the tunnel were wide enough, there shouldn't be too much of an issue for cars, right?

[Frank Lee]

I think it comes down to percentage of "blockage" i.e. vehicle frontal area vs tunnel cross sectional area. I'd imagine a vehicle- especially one that booking along like these race cars- would create a bow wave. The question is how significant is this wave and how does it impact the results?

[gumby79]

A high-speed camera or video and a bag of flower now you can see if thir is a bow effect,and more important your airo shape.
Add a leaf blower to stir the flower into the air
Just an idea. I've used a sandstorm before. Park into the wind 30+mph wind recommended