How do those things work?
Are they gasoline powered, or electric? (How noisy are they?) What is their range? Their ceiling? What is the range of their control signal, and their video output? Do they transmit real-time video, or do you download their camera memory after you recover it. Do they return to their operator information on course, speed, altitude? Do you fly them like a model airplane (by watching them from the ground) or by monitoring the video signal they send back? What is their payload capacity?
I could look it up myself, but I figure you've already researched it. 8)