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Bill,
To the outside atmosphere. I suppose you
could vent to the interior hull, but this concept never quite appealed to
me except to check hull integrity and perhaps with a system like listed
below. Even still, you probably wouldnt be able to get most of the air
inside the hull without a compressor anyways, unless you vented air from the
interior hull at the same time.
Cool thing about kevlar is that it's stops bullets,
around the 20000 psi range (of course this varies wildly dependent upon grade)
and it's flexible and corrosion resistent. (BUT, it's sensitive to light)
Ballast tanks dont need to be too pressure resistent usually, so the strength
isnt as important... nevertheless, kevlar is much more reliable as you dont need
to constantly inspect it and its chances of failure are slim.
The original Alvin design actually used ballast
bladders (found that info. in busby just now), but they pumped oil from them to
ballast spheres. Cool thing about this is like I said before with
consumables, since the bladders are flexible any fuel, oil, water, etc. you use
is compensated by the water that fills the void.. making a more stable
sub. Pumping oils gives you much greater depth capability, as it's
basically a hydraulic system. The air in the ballast spheres is filled at
atmospheric pressure, so you dont need compressed air technically.
It's all done with oil. You could even vent this to the interior
space if needed. Course, the bigger the sub the more air you can
vent. If you're really slick you could use a DUAL ambient bladder system
(assuming your bladder is strong enough). This would take the load off the
pumps by only having to fight the air compressed in one bladder, using the
sea-pressure to its advantage.
SH
----- Original Message -----
Sent: Friday, November 18, 2005 1:59
AM
Subject: Re: Re: [PSUBS-MAILIST] Re:
Variable Ballast Calculations, Bill
Hi Shawn.
Nice concept. I like the bladder idea.
When you said..."Of course, the initial main
ballast vent would be to the atmosphere since it'd probably take FOREVER to
compress them into a tank."
Did you mean the initial vent would be to the
interior hull atmosphere keeping all the air inside like the Hunley, or to the
outside water atmosphere and therefore
you would lose some air? I wasn't quite sure what
you meant on that.
Bill
----- Original Message -----
Sent: Thursday, November 17, 2005 10:13
PM
Subject: Re: Re: [PSUBS-MAILIST] Re:
Variable Ballast Calculations, Bill
Regardless, you still need compressed air to
blow the tanks. Exterior main ballast tanks really only need to be
blown near the surface, where the pressure is less (unless you need some
kind of emergency blow). Just enough to keep you afloat/sink.
It's always smarter to have a pressure tank instead of going "direct".
The main ship compressor simply maintains say a 3000 psi level at all times,
either from surface air or bladder air. All other ballast tanks are
blown from here. Military subs go up and down in this way I'm sure as
it doesnt give off any bubbles, and they raise/lower depth an unlimited
amount of time; simply recycling the air they have.
Figure, you can hold a closet-full of air
inside a small scuba tank. That's plenty. Of course, the initial
main ballast vent would be to the atmosphere since it'd probably take
FOREVER to compress them into a tank. Being able to get
the air back into the sub just seems like an extra layer of flexibility,
albeit unnecessary since you can just use the outside air - hehe. That main
vent would simply be a one-way valve to keep the water out of the
bladder btw.
As for the rest of the smaller ballast/trim
tanks they could more easily/quickly be compressed back into the main
compressor tank.
I guess you could say if you had a ballast/trim
system that really only employed a few tanks it'd be beneficial to use a
bladder as u could use it at depth to raise/lower depth without wasting air
or having to build a bulky ballast tank. The positive pressure outside
the bladder aids in getting the air back into the main compressor
tanks.
Anyways, just thoughts. Those kevlar
pressure bags are very expensive. But it limits component
exposure to the elements and cuts down on airspace. Only really pays
if you're building the "ultimate sub" and mostly is beneficial for
consumable and waste tanks. Using them for ballast tanks just
cuts down on the steel I guess. Still fun to dream
though. :)
All in all, composites are the future for
sub-building. We all know this. Fun to think of ways to apply
the technology.
SH
p.s.
btw, I looked up a few compressors. The
ones fire departments use can do like 20 cubit feet/minute at 6,000
psi. Obviously much faster at lower pressures. Of course, then
you have to factor in the total airspace added from using a large compressor
to begin with. Would simply using more TANKS be better??
UGH! too much to think
about.
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