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 Robotics / Handy Board / 6537
6536  |  6538
Subject: 
Re: submersible, ballast, depth sensor
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Wed, 28 Jul 1999 13:02:26 GMT
Original-From: 
Andrew Harris <mail96928@pop[NoSpam].net>
Reply-To: 
MAIL96928@POP.NETavoidspam
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> 
> Hi!
> 
> I planned to build a sub myself about
> two years ago but couldn't find the time to build it. What I have to
> offer are some thoughts.
> 
> Fortunately a submersible needs lots of ballast, so you can stuff it
> with lots of batteries and gear.
> So my plan was to use a $10 air compressor (the sort you can buy at
> service stations to fill your tires) to move air from a bouyancy
> tank (with a hole at the bottom connected to the water) into a • reservoir
> to sink and to let it flow back through an
> electric valve to rise. This way the only refueling you need is
> electricity. So you don't need to refill the canister from time to • time
> which means maintainance on land.


I'm curious; what is the difference between the "buoyancy tank" and the
"resevoir"?  I'd think moving air from one tank to another won't
actually
affect buoyancy.  Am I missing something?

> My favorite methode would be to use an electric piston system to move
> water in and
> out of a large cylinder (about half a liter). The other side of the • cylinder
> (the air side) must be connected to the interior of the sub. This way
> you would change the pressure inside the sub. Or you could say you
> change the overal volume, hence the bouyancy.


That's interesting; but difficult, right?  Ensuring a watertight seal
around
the piston even under various pressure differences is really hard.  Can
you refer a specific piston system?

> I planned also to build some kind of automatic emergency float system.
> Nothing else than some ballast to drop when the batteries run too low
> OR a preset time has elapsed (the latter could be a mechanical • solution
> using a modified kitchen alarm clock).

That's a good idea.

-andrew
mail96928@pop.net



Message has 1 Reply:
  Re: submersible, ballast, depth sensor
 
(...) Yes. You missed the "with a hole at the bottom connected to the water" which means that water comes in as you move the air to the reservoir. And this means reducing the effective volume of the submersible but keeping its weight. Just the same (...) (27 years ago, 28-Jul-99, to lugnet.robotics.handyboard)

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