jwilli

I work for a 4 letter agency that is trying to go back to the "mall" in 5 years. The talent is a bit lackluster, compared to what I expected.

I agree with your point. 15 year old boys are by no means a good sample for the population as a whole. I would argue 15 year old boys are in fact one of the worst samples for this study. Aren't boys going through puberty known to be reckless and shortsighted?

It's new because it is being done in the atmosphere. I work with Autonomous Underwater Vehicles (AUV) which have employed this method of propulsion for at least a decade. For AUVs the variable buoyancy is achieved by having an expandable bladder of fluid which can be contacted to allow ballast to enter or expanded to expel ballast. Check out Slocum gliders if you are curios