Re: [PSUBS-MAILIST] Ambient pressure design considerations

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

Hi Carsten,
Thanks for the reply, but I'm quite puzzled by your statements?
The reason I want "small and hydrodynamic" is not to go fast, but rather to
minimize thrust requirements.
The sub, as stated, is designed for 0 to 33 feet, not 99 feet.  If something
went terribly wrong and I found myself at 99 feet of depth, I would
certainly hope to have more than 50 psi of pressure in my air tank anyway so
they are not going to crunch.  Even if they were down to one atmosphere they
would not, so I feel like I must be missing your point entirely.  Are you
refering to hull failure due to a failure to maintain ambient pressure?  If
so, I understand your concern but maintaining ambient pressure will be an
entirely seperate system and will not rely on my breathing apparatus or
supply.  As I stated, I do have some questions relative to ambient pressure
but I've saved those for a later post.

Again, thank you very much for your input.  This is all mostly new to me, so
if I'm misunderstanding then please clarify.

Dave Altis

----- Original Message -----
From: "Carsten Standfuss" <MerlinSub@t-online.de>
To: <personal_submersibles@psubs.org>
Sent: Saturday, November 01, 2003 3:44 PM
Subject: Re: [PSUBS-MAILIST] Ambient pressure design considerations


> Hi Dave .. the only problem I see is the size of the regulator and the
> size of the air tank..
>
> If you write " small and hydrodynamic as possible" that indicates that
> you can change the deep very fast. From 33 feet to 99 feet in how many
> second ? And if the regulator or air tank is to small... crunchhh...
>
> regards Carsten
>
> > Dave Altis schrieb:
> >
> > 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
> >
> >
>
>