Enter: Virgin Oceanic

[Dr Mordrid]

First Virgin Galactic sets on a course to put civilians into outer space, and now Virgin Oceanic plans on sending them to inner space -

http://www.virginoceanic.com/

Imagine if you could pilot a submarine anywhere in the ocean – crushing pressures and freezing temperatures no longer an obstacle to your journey. Where would you go? What would you hope to see? The possibilities are infinite…

[VJ]

The concept of "flying underwater" is an interesting one and prototypes have been made: it allows for far less bulky submarines. I just wonder what happens if the propulsion fails... A plane can glide its way down, but given the higher resistance of the water, I would guess the submarine would shoot straight up (I can't imagine control surfaces would allow enought control to slow down the ascent)...
Of course, as long as the hull is pressurized at 1 ATM, there would be no decompression issues. But it would imply a VERY tough hull... pressure at those depths is immense... It would also be pitch dark, even with strong floodlights visibility would be a matter of metres.

I don't see it happening (soon) to go to great depths for toursit purposes, but it who knows... But I do appreciate the fact that they are trying to push the envelope again. Can only be good for science as well.

[Dr Mordrid]

What info I have is the hull is a very strong composite. As far as control in an unpowered ascent; I imagine it could work like a reverse glider, turning verticle forces into forward motion, if net ascent has to be slower. Just spiral up.

[VJ]

That is the thing: if you dive, and let something lighter than water go, it goes up and accelerates quickly, it seems like it gets a much stronger force than 1G (in the upward direction). So I wonder if the vertical acceleration is not too big to make it work like a reverse glider... Once the speed is too high, I would image the "wings" to stall, just like a high-speed stall in an airplane.

The pressure down there is 1000 ATM... so that is quite huge... Not saying it is impossible, but not too convinced light materials can handle it.

[Dr Mordrid]

It uses a carbon-Kevlar-Vectran reinforced polymer made for submarine hulls, which the USN & DARPA are also looking at for deep diving minisubs.