Develop slow smoke for mini windtunnel I want to create a small wind tunnel for testing of aerodynamics for Radio controlled units (Cars, planes and helicopters).

In real wind-tunnels water mists are used but water isn't a good thing for the electronics.

I have considered the following:


Smoke bombs, but the smoke develops too fast.
Burning stuff like laves or coal, but it creates odor, and i don't want my RC stuff to smell.
Incense, same as above.


My chemistry level is a College equivalent degree of chemistry that has been unused for 15 years.

And the materials to make this should be somewhat harmless, and legally available.

Any suggestions on how to do this would be highly appreciated.
The DLR (German Aerospace Center) has developed a couple of DIY instructions for school education. Among these is a PDF in German for the construction of a wind tunnel.

For the smoke, they suggest to use either 


incense (the sticks or cones that you usually find in asia shops or esoteric shops) or a   
fog machine, like the ones used for entertainment (dance clubs, etc.)


In the latter case, a mixture of 1,2-propanediol and water is heated and pressed through a nozzle at elevated temperature. Given that properly insulated machines, build for safe use at home, are available from DIY electronics shops for roughly 30 € up, I wouldn't start to build one myself.