Missing sub

[Fredxx]

I don't think air bags would work very well, at 400 bar a bag would be

1/400 the initial buoyancy at sea level

I guess Lithium dissolved in Ammonia might do the job?

[Colin Bignell]

If it imploded at the time they lost contact, which seems likely, it was about 300m above the sea bed.

[GB]

That's not an issue. There'd be a pressure relief valve, rather than having the bag swell up to 400 times the size (then go pop!).

[GB]

I had 800m in my mind, but ...

[Colin Bignell]

It was rated to 1300m, but Stockton Rush claimed that the standards were excessively cautious and that the acrylic would start to show stress crazing long before it failed, which was the point at which the submersible should return to the surface.

The body of the machine, can take

In an interview last year, he claimed to have developed the design as part of a contract with Boeing, with help from the University of Washington.

[Colin Bignell]

The reports I read said they were 3,500m into a 3,800m descent.

[Colin Bignell]

The other problem being the reason that deep dive submersibles drop ballast, rather than blow tanks to rise: not being able to have air at a higher pressure than the surrounding water.

[GB]

Is there a practical limit on air pressure at 0 C?

[GB]

The reports I read said they were 3,000m into a 3,800m descent. :)

[jon]

I just saw this article:

Capabilities

According to documents submitted by OceanGate to a U.S. District Court in Virginia overseeing Titanic-related matters, the Titan has the capability to dive to a depth of four kilometers (2.4 miles) with a sufficient safety margin. The company stated this information in its April filing.

In the event of an emergency, the Titan is equipped with safety mechanisms that facilitate its ascent to the surface. These built-in systems include the ability to release sandbags, le ..

Read more at:

[GB]

You mean

[Colin Bignell]

<huge link snipped>

From what I have read there were multiple ballast release systems. The main one was hydraulic and released iron pipes. The emergency one was to get the occupants to move from side to side, to tilt the vessel, so that ballast rolled off the frame. The back-up one was ballast connected with links that dissolved in seawater over a 16 hour period. None of which really help if the pressure vessel has imploded.

[Colin Bignell]

It is more a practical limit on the cylinders needed to hold that much pressure at the surface and on the pumps you would need to pressurise them.

[Rod Speed]

And even if you can find one like hydrogen which has a high enough pressure, there will be a problem with it going bang as it rises.

[Rod Speed]

Wouldnt work at all in fact, it would burst on the way up if you inflated it with hydrogen which is at a higher pressure than 400 bar in the cylinder.

Thats not the problem.

Nope, the bag would still burst on the way up.

[Colin Bignell]

Weather balloons address that problem by only partly filling the envelope.

[Rod Speed]

But they don't see anything even remotely like a 400 times change in pressure outside them.

[John Walliker]

That doesn't matter. You just leave the bottom open and the excess gas escapes.

John

[Clive Arthur]

<snip>

And even if they did have cylinders to store air at 401 bar, the volume of the gas at 400 bar ambient wouldn't be much more than the volume of the cylinder, so bugger all lift.

[Rod Speed]

Have fun explaining why they dont do floation bags like that.