I would think airspace is more of a problem than being shot down. I know they have done 60 plane hovers at PRO BRO Meets each plane taking a 25 sf space. 5 planes per 150 yards of field is my limit. That is regular type flying. Add hovering pilots and it depends on who it is. If they are in my face I land too. The only contests I go to are scale and at best there is 4 flying at once; that and dwindling participation has no prob with too much going on. Joe Nall should have a limit for airspace reasons. Having 10 planes, 10 helicopters, 10 others all at once is a lot to try and watch at one time.