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Hi Doug. The fiberglass container would still be subject to external
pressure, as the filler bubbles would still have 1 atmosphere air around
them if the hole was "plugged".
If the pressure was great enough to stress the fiberglass walls to the
point of cracking, or even rupture, you may start to lose the glass bubbles. If
you lose the glass bubbles, your sub becomes heavier in relation to it's
displacement, and you sink.
You could use HP air to compensate the external pressure, say with a scuba
regulator , connected to the tanks, but you'd have to make sure the air is
dumped as you ascend.
Seems like it's pretty complicated for what you achieve, ie: some extra
buoyancy.
why not just build the tanks out of steel, thick enough to withstand the
pressure, and bolt them on. Or if weight is a problem, aluminum
sheet rolled into the general shape, and covered by a fiberglass fairing of
the desired shape for that "sleek" configuration to fit the hull.
My sub needs 750 pounds of lead just to sink when the main ballast tanks
are full of water.( plus trim tanks half full and additional lead
ballast on the floor ( about 250 pounds )
When I drop the 750 lbs emergency drop weight, ( if I need to ) it
should float like a cork.
These are rough numbers, but the total displacement is about 8700 lbs. and
the finished weight including passenger and pilot, is around 7600 pounds.
I read where ABS says that your sub should be slightly positive buoyant at
all times so if a major failure occurs, or you become unconscious for some
reason, the sub will float to the surface by itself. The use of thrusters
pushing the sub down to maintain depth was the preferred method.
I'm not so sure I like the idea of using battery power to stay down, but it
does add another safety factor to the overall design.
Is your sub so heavy you need the additional buoyancy? Why not make the
interior space a little bigger, and get the buoyancy from a space you can use.
Frank D. See what's free at AOL.com. |