Well, it looks nice so far. This supercavitation sounds a lot like the underwater warp drive I once played with. The only problem with my version was that the bottom of the shell had to be open to allow water to flow in. If not, the sub had nothing to float on and it would race to the bottom of the ocean. Supersonic landings are not pretty.
What I like most about your design are the rings though they look a tad small to me. I don't get the feeling of an uberpowerful, supersonic propulsion system. On the other hand, making them too big would make the actual sub feel unimportant. Balancing is hard I guess.
Anyway, I'm going to read up on this supercavitating thing. Supersonic subs, really cool. And sound travels faster through water than through air, so supersonic is really supersonic here. Hmm, I wonder how high up in the air a supersonic sub could go if it breached the surface at full speed and straight up.
