QUOTE (NorthSideSox72 @ Oct 16, 2009 -> 09:46 AM)
It can't be that simple. There is math involved - if there is enough helium, weight of child, weight of balloon, weather factors, etc. You can't simply look at a balloon and say "nope, couldn't do it", unless it was patently obvious (like, no, that party balloon twisted into a cute doggie could not lift Refrigerator Perry into the sky).
The dimensions were plotted to be 20 x 5 or 1,000 square feet. The known lift of helium placed the max lift at 100 pounds. And of course that isn't lift to 5,000 feet. Plus you have to subtract the weight of the mylar