Was reading some online research papers on micro AUVs looking for tech particularly ballast systems which may be applicable to our hobby. Turns out it's the other way around, AUV builders are copying ours. They're a little bit more high tech but the core principles are there. Why waste time designing your own when it's been used and proven by modelers for decades. Gas systems, piston ballast systems made from syringes, bladder bags with water pumps, even RCABS. 
