Here's a video from one of our recent tests of our GTQ-Cormorant: a submarine and quadrotor hybrid.
We use an air pump/solenoid system to move air between the clear, water-tight pressure hull and an external air bladder for depth control (down to around 7' in this test). An APM 2.5 controls SAS and pump/solenoid switching. We use the barometer onboard the APM as a depth sensor.
More details and videos will be posted soon: http://www.uavrf.gatech.edu/
We can and do! It just takes more current to use the flight propellers underwater.
Shame you can't operate the quad underwater to maneuver around! ;-)
Hey! I use to swim in that pool. :) Nice work.
Gotta love it! The depth control is really interesting to see.
Well done and well executed. Most impressive!