>line-of-sight quad-copters that can stay up for 20 minutes
10 minutes is the median, but they don't have to be line of sight, except as bound by regulation such as in the UK [0]. Still short-range though, and certainly not suitable for this use-case.
10 minutes is the median, but they don't have to be line of sight, except as bound by regulation such as in the UK [0]. Still short-range though, and certainly not suitable for this use-case.
[0] http://en.wikipedia.org/wiki/First_Person_View