Mariana Trench Deep

[Hanoixan]

Most people on this site don't seem to be thinking about going really deep. But, for the sake of argument, let's say I wanted to design an object housing electronics to sink 11km deep, to the Challenger Deep of the Mariana Trench. It's very cold, and the pressure is almost 16,000psi.

What would be the simplest, cheapest, most brute force way to encase my electronics (which would include LED lights and a camera)? Total electronics package measures about 6"x3"x1". To make this even more fun, let's say I want the electronics to be consumer-grade, so I can't rely on tantalum capacitors.

The object will not have external thrusters, etc. For the sake of this post, it's simply made to sink.

[scubersteve]

Start with a solid acrylic sphere 2 feet in diameter.
Cut it in half and hollow out the middle leaving 6 inches of wall thickness.
Machine a o-ring groove in both sides (1 more than the other)
Put your electronics inside and use bands to strap the whole thing together.

I have no idea what I'm talking about.
Welcome to the forum.

[Hanoixan]

Thanks. I think you're on the right track. I did some calculations, and I think for those kinds of pressures, I can get away with a wall thickness to sphere diameter ratio of about 0.2055. (you were pretty close!--for your 24" sphere and 6" walls, that's a 0.25 t/D ratio). So, with a 5" air sphere in the middle, the whole thing ends up being about 8.5" wide with 1.75" thick walls. This is based on this book: http://www.archive.org/stream/developme ... 0/mode/2up

I wonder there's any better math for designing an acryllic shell for a given hydrostatic pressure...?

[fluxno]

national geographic has done this already. they talk about it in this video: http://www.youtube.com/watch?v=VrcWD2Ok ... r_embedded
there are probably more information about this system other places aswell.
they use glass spheres, and use just glass-vs-glass as sealing as i understood.

[Hanoixan]

Fluxno, thanks a ton. This simplifies things for me quite a bit. I did try finding information on this, but I didn't really know what to search for because I was assuming acrylic was the go-to material. Thanks again.