Sometimes it takes videos like this to really drive home the fact that the atmosphere is really just a big gas ocean, that displays basically the same physical properties as a liquid ocean. Festo took this concept to heart when they designed the Air_ray, a remote controlled blimp that swims through the air just like a manta ray. The blimp is filled with helium, making it buoyant, and contains servos which flap its wings, propelling it through the air and allowing it to maneuver. It also seems to have a movable tail to control pitch. Overall, it makes for a very organic form of propulsion; click on for a soothing video of the Air-ray flapping around.