As for the glue and durability...I have something to say about it: almost 10 years ago I made an experiment that I recently applied in my Seawolf, the ballast system. Guess what? That (500cc) bag is still glued to the hose and works. I have a vid that I didn't post but I'll do it if I find it. Then, I didn't build RC subs, but just for curiosity I experimented with the ballast system I finally used now.
As for the TR1700...three different guys of our association made the calculations and tests (one of them a naval engineer involved in the design of the TR1700 for the Argentine Navy, he gave us a full detailed and comprehensive lesson about the sub, I even visited it in the shipyard where it's cut in half, being refitted and given maintenance), well, depending on all the extra features you are going to install (masts, torps and all of that), you'll need 800cc to 1100cc of water to dive it.
Mine will need just 800cc or so to dive. I'll use two 1000cc bottles, one of them will take water and the other connected to the former just to keep air pressure low (I mean, in a worst case scenario, I will compress the air to half its initial volume). A solenoid valve will prevent water from escaping this way keeping (as close to neutral as possible) buoyancy.
The quantity of water needed to achieve that neutral buoyancy will be limited by a screw which will limit it according to pressure build-up. I find it hard to explain it now, I'll make a diagram. And the adjustment will have to be made from the outside, I don't want to detach the WTC from the hull tens of times before finding the correct setup.
APC, ADC, etc? Man, this is Argentina, all those nice electronic gadgets have to be imported from abroad, not easy, not sure, not cheap. That's why many of us creat our own solutions.
By the way, this is our site, in Spanish, but please click on the pictures accessed by the sections at the left menu:
www.camne.com.ar
Regards
Robert