WAG this

http://www.csmonitor.com/Innovation...chard-Branson-s-newest-toy-A-flying-submarine

Probably someone can end this by just quoting something, but I wanted to guess what it would take in skin size to do this. My guess is:

A tube that would be strong enough at the surface would take 1/4" plywood (obviously the supporting structure used is huge variable, but tough)

At 36000 feet the load would be @ 1000 times surface. So the material would need to be 32 times stronger, or 8 inches of wood.

My WAG is that is 1-2 inches of carbon. 1 being what I think it is and 2 being my degree of comfort.

Anyone have a guess?

 

Pressure of about 1100 standard atmospheres, say 110 MPa. It looks about a metre-twenty in outside diameter, say 60 cm radius. The mechanical properties of carbon laminates are all over the map, but let's say 550 MPa ultimate strength in compression. A very rough back-of-the-envelope calculation for a cylindrical pressure vessel suggests anything less than about 8 to 10 cm thick will probably rupture. So my guess would be that they have at least four inches of solid carbon composite, if that's what the pressure hull is made of. Since being overweight is not an issue with submarines, it wouldn't surprise me to see six or seven inches, maybe even more.

What a change from bathyscapes, eh? I'm glad Deep Flight's ideas about underwater movement are catching on. This is way cool.

 

If you look at it, notice carefully that the "canopy" is actually free flooding NPH and that behind that is the acrylic sphere for the pilot. That is the only manned space in the whole vessel, everything else is either ever buoyant or small, possibly compensated, electronic bottles which are standard design items. This is very similiar to many small shallower one-man ADS's and WASP except that this one has a very expensive faired NPH vice the safety of not haveing one. It uses existing glider technology and is a better shape than some of the earlier mock-ups that were rolled out. I notice in a press release that he won't be doing the first cert dive.

 

Good point about the outer canopy. I doubt there's any transparent material in existence that could withstand 110 MPa in such a shape.