I used to work for Horizon Hobby and they are the largest distributor of aviation model products. We have an item called The Blade that was a small R/C heli. http://www.horizonhobby.com/Products...rodId=EFLH1300 Anywho, we would fly those indoors here http://www.uni.uiuc.edu/athletics/venues/armory.php and we never had a problem with hitting each other. Of course, we had airplane models too and never hit each other. I guess what I am trying to say is that if you are flying power models, you HAVE TO stay ahead of the model and there won't be troubles. This stuff is awesome