[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PSUBS-MAILIST] Simplist VB System
Just a quick thought based on how you said an oil bladder system "is
changing the amount of air volume _inside_ the sub."
Does it necessarily have to be an oil bladder system? Why not have a
bladder inside the sub filled with water that can be directly pumped
into the surrounding water, and then filled back up using ambient
water pressure and a valve to the outside.
It'd be somewhat simpler than having two bladders and having to deal
with the oil. I guess the main difference is that the oil bladder
system makes the overall water displacement of the sub larger without
increasing weight, therefore increasing bouyancy. Pumping water
overboard would simply act to decrease weight.
Otherwise, only mechanical concern I would have is a pump that has a
good lifespan pumping dirty/salty water. If the pump or the valve
breaks, you've got a direct line in from the outside, and a bladder in
the sub that would inflate like a balloon and pop fairly quickly.
-Ryan
On Thu, 12 Aug 2004 08:40:49 -0700, Michael Wright <mwright@smallip.com> wrote:
> The advantage of an oil bladder over an air bladder is that it isn't
> compressible and thus wont change volume as depth increases. No volume
> change means no change in buoyancy.
>
> What you're basically doing with the oil bladder system is changing the
> amount of air volume _inside_ the sub. The weight of the sub and the
> oil is constant, so if you increase the volume of the combined system
> you increase it's buoyancy.
>
> The problem with an air bladder (such as a BCD) is that as depth
> changes the buoyancy changes in a way that causes the depth to change
> more (a feedback loop).
>
> In SCUBA there isn't another convenient way to do it (and the diver has
> a lot of compressible flotation anyway). The SCUBA diver also has a
> second variable air bladder they can use for quick small adjustments
> (their lungs).
>
> In a submarine you don't have that so it's critical to keep your
> compressible flotation to a minimum. There is also the issue of task
> loading on the operator, though a person could probably manage a spongy
> variable ballast system it would be a really bad idea given the number
> of other things the pilot should be monitoring.
>
> This would be applicable to both ambient and 1 atm subs since both
> displace a constant volume of water regardless of depth.
>
> mike
>
>
>
>
> On Aug 11, 2004, at 8:44 PM, david cutajar wrote:
>
> > I would think that the simplist system would mimick
> > the BCD we use when we SCUBA. Exactly as Dave stated,
> > just an external Bladder; but why not just use Air -
> > is it too compressible and must be adjusted more often
> > than oil? i.e. compresses too much as you descend???
> >
> > I wonder what the advantage of oil in this situation?
> > Is it the ability to pump it back in and it doesn't
> > use up all that air???
> >
> > For air, just have a momentary valve for input (into
> > the blader) and one for output (exhaust out of the
> > bladder)and make small adjustments to your bouancy as
> > required.
> >
> > just some thoughts---$.02
> >
> > David Cutajar
> >
> >
> > --- Mark <gadgetsboy@ntlworld.com> wrote:
> >
> >> I'd be interested in a look myself
> >>
> >> Mark
> >> ----- Original Message -----
> >> From: JANE PATTON
> >> To: personal_submersibles@psubs.org
> >> Sent: Wednesday, August 11, 2004 5:50 PM
> >> Subject: Re: [PSUBS-MAILIST] Found this article
> >> and thought it may be ofinterest
> >>
> >>
> >> Hi Dave
> >> Where could I find a sketch of the oil bladder
> >> system you speak of?
> >> Rick
> >> ----- Original Message -----
> >> From: Fly Deep
> >> To: personal_submersibles@psubs.org
> >> Sent: Wednesday, August 11, 2004 5:24 AM
> >> Subject: Re: [PSUBS-MAILIST] Found this article
> >> and thought it may be ofinterest
> >>
> >>
> >> Mark, the easiest and simplest VB system I've
> >> ran across so far is one smiler to what is used on
> >> the Deep Workers. Its a simple oil tank on the
> >> inside and a small hand pump like a jack that can
> >> push the oil to the outside of the pressure vessel.
> >> As the bellows increases in size out side the
> >> pressure vessel it displaces water and there by
> >> adjusting the Buoyancy....Dave
> >>
> >> __________________________________________________
> >> Do You Yahoo!?
> >> Tired of spam? Yahoo! Mail has the best spam
> >> protection around
> >> http://mail.yahoo.com
> >>
> >
> >
> >
> >
> > ***********************************************************************
> > *
> > ***********************************************************************
> > *
> > ***********************************************************************
> > *
> > The personal submersibles mailing list complies with the US Federal
> > CAN-SPAM Act of 2003. Your email address appears in our database
> > because either you, or someone you know, requested you receive messages
> > from our organization.
> >
> > If you want to be removed from this mailing list simply click on the
> > link below or send a blank email message to:
> > removeme-personal_submersibles@psubs.org
> >
> > Removal of your email address from this mailing list occurs by an
> > automated process and should be complete within five minutes of receipt
> > of your request.
> >
> > mailto:removeme-personal_submersibles@psubs.org
> >
> > PSUBS.ORG
> > PO Box 311
> > Weare, NH 03281
> > 603-529-1100
> > ***********************************************************************
> > *
> > ***********************************************************************
> > *
> > ***********************************************************************
> > *
>
> ************************************************************************
> ************************************************************************
> ************************************************************************
> The personal submersibles mailing list complies with the US Federal
> CAN-SPAM Act of 2003. Your email address appears in our database
> because either you, or someone you know, requested you receive messages
> from our organization.
>
> If you want to be removed from this mailing list simply click on the
> link below or send a blank email message to:
> removeme-personal_submersibles@psubs.org
>
> Removal of your email address from this mailing list occurs by an
> automated process and should be complete within five minutes of receipt
> of your request.
>
> mailto:removeme-personal_submersibles@psubs.org
>
> PSUBS.ORG
> PO Box 311
> Weare, NH 03281
> 603-529-1100
> ************************************************************************
> ************************************************************************
> ************************************************************************
>
>
************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003. Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.
If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
removeme-personal_submersibles@psubs.org
Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of receipt
of your request.
mailto:removeme-personal_submersibles@psubs.org
PSUBS.ORG
PO Box 311
Weare, NH 03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************