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Re: [PSUBS-MAILIST] Ambient pressure design considerations
Hi Pierre,
That would be great, I'd love to see the power-point presentation.
I'll try to post some drawing files soon.
Thank you,
Dave Altis
----- Original Message -----
From: "pierre&marie" <poulin.carrier@videotron.ca>
To: <personal_submersibles@psubs.org>
Sent: Monday, November 03, 2003 6:02 AM
Subject: Re: [PSUBS-MAILIST] Ambient pressure design considerations
> Hi Dave!
>
> I'm also building a dry-ambient sub. Me and Jon Wallace made a
presentation
> for the last psubs convention. It's a power-point presentation explaining
> some principle and building process of my project.
>
> Let me know if you would like to have it. I can e-mail it to you directly.
>
> Also, I'm very interested in your project. Do you have a drawing of your
sub
> that you could post on the moki exchange files? That would be great.
Always
> easyer to talk about something we can see...
>
> Talk to you soon!
>
> Pierre Poulin
>
>
>
> ----- Original Message -----
> From: "Dave Altis" <dabe@fidnet.com>
> To: <personal_submersibles@psubs.org>
> Sent: Sunday, November 02, 2003 11:54 PM
> Subject: Re: [PSUBS-MAILIST] Ambient pressure design considerations
>
>
> > Hi Jorge,
> >
> > Thanks for responding. I could not agree more about having little use
for
> a
> > semi-dry sub (I've seen no sharks in the lakes around here), which is
why
> I
> > wouldn't bother! ( There are some rather large catfish though! ) I
> > understand the engineering challenges involved in ballasting and boyancy
> > control of an ambient sub and I understand Boyle's law, but I also
> believe
> > I'm quite capable of overcoming these challenges and I believe I will.
If
> I
> > find I cannot, I'll build a 1 atm before I go with a wet sub. I know
> > condensation will happen anyway, but I still feel like it will help if
I'm
> > not breathing on the window I'm trying to look out of. Thanks for
> pointing
> > me to the SportSub site, I found answers to a couple of questions there.
> >
> > I fear I've given the wrong impression to several of the group by
refering
> > to my "ignorance". Please don't confuse this with a lack of
intelligence.
> > I've accomplished a lot of difficult things that a lot of well-meaning
> > scoffers have said "can't be done". The sub has been an ambition of
mine
> > for many years, long before I knew of this group's existence. One of my
> > greatest areas of caution underwater is entrapment, a friend of mine
> watched
> > his son die that way, the least thing I want to do is become entraped in
> my
> > own devices. I'm just trying to cover all my bases here, learn from the
> > mistakes and experience of others, not become another statistic. No, I
> > don't know it all. That's where the "ignorance" comes in, but I intend
to
> > learn all I can to make this as safe as it can be. That's how I found
> this
> > group.
> >
> > Thanks again, (it did help!)
> >
> > Dave Altis
> >
> > ----- Original Message -----
> > From: "Jorge Lourenço Jr." <jorloujr@uol.com.br>
> > To: <personal_submersibles@psubs.org>
> > Sent: Sunday, November 02, 2003 2:56 AM
> > Subject: RES: [PSUBS-MAILIST] Ambient pressure design considerations
> >
> >
> > >
> > > Hi, Dave !
> > >
> > > Being a hard-core full time lurker myself I'll dare this time to
> disclose
> > MY
> > > deep ignorance, following your (good !) example:
> > >
> > > I think that there is no point building a sub where you are wet and
> > wearing
> > > a mask (yeah, I recall your saying DRY, but I'd bet it's gonna be a
> > semi-dry
> > > vehicle due to ballasting issues...). The only justifiable thing I can
> see
> > > in this approach is the protection against some environmental hazards
> > > (sharks ?). We'd be better off diving donning the regular diving gear
> and
> > > being pulled by a scuba tow. That means a lot of speed, greatly
extended
> > > bottom time and unsurpassable freedom of movement. And a lot cheaper,
> > let's
> > > not forget ...
> > >
> > > If I ever build an ambient dry submersible I'll mimic the SportSub [
> > > http://www.ivccorp.com/ssinfo.html ] and the Markham Wing [
> > > http://www.psubs.org/pic/wet.html ] designs, for instance.
> > >
> > > The SportSub features a continous flow air feeding device that sweeps
> away
> > > the stale air and besides that has the advantage of providing a
> > rebreathing
> > > effect that circumvents the oxygen waste of a scuba (open circuit)
gear
> > > extending bottom time about four times. This is not to be despised. By
> the
> > > way, CO2 buildup is not a concern, if you are not diving for hours,
even
> > in
> > > the K-250, where the breathing air is what is entrapped inside the
hull
> > when
> > > the hatch is closed, and moisture condensation will happen anyway,
> > requiring
> > > more than fresh air to be avoided.
> > >
> > > The Markham Wing has a simple pipe pivoting around its elbow to set
the
> > > water level inside the "cabin" thus controling the buoyancy.
> > >
> > > Both devices are very simple, easy to build and operate, reliable and
> > cheap,
> > > fully adhering to the K.I.S.S. principle, leaving little to be
desired.
> > >
> > > That's it for now, hope it helps...
> > >
> > > Jorge L.
> > >
> > >
> > > >
> > > > 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
> >
>
>