This may sound crazy. How about a quadcopter designed for underwater use. Brushless motors operate perfectly well submerged and the rest can be waterproofed quite easily. Idea being that one would use small props, basically the quad would operat
I have been flying my DIY quadcopter for about 2 months now and although it is very stable, I have a small yaw issue. For example, if I yaw clockwise the quad will yaw correctly to that point but then yaw anti-clockwise about half of it's orignal