Thanks; I really appreciate your comments. I will give it a shot without the tube and see what happens. Although I'm guessing I will still need a way to direct the air as the fan is still pretty omnidirectional.
It's hard to gauge the response time so far as I haven't quite figure out the air flow right. But, it seems to be pretty responsive on start up. It's a bit unstable right now with anything less than 100%. But, I think I just need to get the airflow right and that should help.
The ball spins at a pretty high (and consistent) rate. I wonder if there would be a way to do a led POV on the ball without adding too much weight.
Thanks again,
Mike