Hi, very interesting thread.
Im not a flight tester of any sort (can only dream of eventually being one).
I might be well off the point here (probably) but would using a small remote controlled petrol helicopter in a big hangar not work .
It would be quite cheap and the downwash would have more of an affect on the smoke generated from a smoke grenade.
You could even tie the helo to a stick or something so its easier to control?
Anyway, just a thought would like to know if/ why this wouldn't work.
Thanks very much guys.
Ghostie