Re: [PSUBS-MAILIST] Ambient pressure design considerations

["Dave Altis" <dabe@fidnet.com>]

Hi Doug,
Thanks for the reply.  Your sketch is very close to what I had in mind with
just a couple of exceptions:  I had planned on using a mask rather than a
mouthpiece.  This way I can breathe through my mouth and/or nose at will.
The design of my second stage regulator will allow an outward flow only so
no need for a check valve there, the exhaust line of course would require a
check valve.  No thanks on the warning system :)  I'd like to build a two
man sub, but my first will be a one man.

Dave Altis

----- Original Message -----
From: <DJACKSON99@aol.com>
To: <personal_submersibles@psubs.org>
Sent: Saturday, November 01, 2003 2:14 PM
Subject: Re: [PSUBS-MAILIST] Ambient pressure design considerations


> Hello Dave
>
> That sounds like a great idea, and one I may steal, not only to reduce
condensation but to also conserver air.   Here is sketch of what I think you
are describing. With this design you would breath in through you nose and
out through your mouth, like a runner.  Optionally you could put a second
check valve in the exhaust line in order to not make that a choice. But if
you have no second check valve in the exhaust and your regulator stopped
working on decent the mouth full of water would be a great warning system :)
> http://jackson.parcabul.com/sub/images/air_supply.jpg
> Also on Monki: http://www.prismnet.com/~moki/subfiles.html
> I'd supplement the design with a valve that could bleed air into the cabin
from the 1st stage so you could optionally breath without the mouth piece.
This 1 or 2 persons?
>
> -- Doug Jackson
> http://jackson.parcabul.com/sub
>
>
>
> In a message dated 11/1/2003 12:09:31 PM Eastern Standard Time,
dabe@fidnet.com writes:
>
> > Okay, I've silently observed this list for some time now and I'm ready
to disclose some of my ignorance to the group in the hope of gaining some
valuable input.
> >
> > My intent is to build a small ambient pressure dry sub for recreational
use in the fresh water lakes of my area.  The conceptual design would be
limited (by pressure switch) to a depth of 33 feet (aproximately).  I need
to keep the sub as small and hydrodynamic as possible to minimize power
requirements.  The sub will remain slightly positive in boyancy and will
power-dive using dive planes which will be linked via a mechanical mixer to
provide both pitch and roll control.  A control stick and rudder pedals
would be incorporated as in an airplane (like flying under water).  If the
craft exceeds the depth of 33 feet the pressure switch will deactivate the
motor thereby forcing it to ascend back into its window of operation.  An
emergency override switch will allow the use of power beyond the 33 ft.
limit.  My plan is to breathe compressed air through a two-stage regulator
(scuba) with an exhaust duct to carry exhaled gasses to the outside of the
sub.
> >
> > Any red flags yet?
> >
> > By exhausting the exhaled air to the outside I hope to minimize moisture
condensate and CO2 buildup inside the sub, however, I realize in order for
this to work it is absolutely essential that the air pressure inside the sub
remain ambient to the pressure outside the sub.
> >
> > I have to go for now, but I have more questions relative to ambient
pressure and boyancy to come in another post.  I'm not looking for ridicule,
but if you have some constructive criticism or see cause for concern with my
plans thus far, I
> > would value your input.
> >
> > Thanks,
> >
> > Dave Altis
>