Next Generation Sub Update

Joe Buff has a good article on the current vision for the proposed Virginia-class follow-up, Tango Bravo, over at military.com. I agree wholeheartedly with this statement from Joe:

"So a bit of healthy disbelief seems advised when TANGO BRAVO's goal is labeled as “the same or better mission capabilities for half the money,” or claims are made that “with concerted effort, an SSN design derived from TANGO BRAVO would be ready for procurement in 2011 or -- under ideal conditions -- even earlier.” On the other hand, we can't afford to not do TANGO BRAVO, or our own expertise base will wither irrecoverably, and we won't have a good follow-on class beyond the Virginias."

Initial cost estimates for Virginias back in the 90s were something like $1.3B per boat, which was only slightly more than an LA was going for at the time -- this was clearly unrealistic, but Congress signed off on it.

I'm especially interested in the concept of "shaftless propulsion"; so interested, in fact, that I did some research on it before I left the service, so I can't really talk about it. Here's what Joe has to say:

"The propulsion shaft of current SSN designs is long and rather heavy, causing center-of-gravity (trim) difficulties for naval architects, and the shaft requires a large hole in the stern of the pressure hull. Moving to all-electric propulsion, with the drive motors encased in pods outside the people tank, and with hull penetrations needed only for power cables that don't rotate, is a very attractive alternative. A word of devil's advocacy, though. A commercial ship with a similar arrangement recently suffered a serious fire in one such pod; no one was injured, but the ship was crippled. And this was on the surface with help nearby -- not deeply submerged during battle maneuvers. The tech for submarine use will surely get there, but the point is it isn't there yet and it won't be cheap."

An advantage of "shaftless propulsion" with electric drive is that all of the reactor's usable output could go to generating electricity; in theory, you could divert that electricity to other interesting things when not needed for propulsion. (Right now the other interesting things are most usable for surface ships, but I'm sure some smart submarine guy could figure out how to make subs use the extra power as well.)

Anyway, read the whole article -- and check out the rest of Joe's archives if you get a chance! (At this point, I should point out that in my last post about one of Joe's articles, I kind of got on him about HF sonar; I realized in hindsight that even a civilian writer has to operate under a lot of restrictions that we sub-bloggers are bound by, and I'm sure Joe knew what he was talking about.)