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RE: <SPAM> Re: [PSUBS-MAILIST] Newbie needs help
Sounds pretty complicated.....
Hugo
-----Original Message-----
From: Ian Roxborough [mailto:irox@ix.netcom.com]
Sent: Friday, May 27, 2005 1:26 PM
To: personal_submersibles@psubs.org
Subject: <SPAM> Re: [PSUBS-MAILIST] Newbie needs help
On Fri, 27 May 2005 09:51:43 -0700
"Chuck Will" <chuck@bestan.com> wrote:
> I plan on using an air pump, not a compressor. The air pump is high volume
but
> low pressure. Like the kind you use on you fish tank but many times
greater
> volume.
Hi Chuck,
You say that you are using a high volume low pressure pump to expell
air from the rear of your submersible. How 'low pressure' is this
pump? Will it beable to over come water pressure at max operating
depth when expelling stale air?
There is noway of avoiding the fact that you'll need to use more power
to expell the air the deeper you go. Deeper dives will take more
battery power.
If you really have problem with compressed O2 and your dive times are 1
to 2 hours, then perhaps look into the surface and replenish method
(no pressurized O2 requried). This is proven and your cannot get
much simipler to operate or easier to construct.
> That way, most of the dive is at 1 ATM but during air exchange, it
> may increase up to 1.5 ATM for a couple minutes. It would be like doing a
> shallow scuba dive to 15 feet for a few minutes.
Changing pressure by 50% over a fews minutes, several times over the
course of a dive, might be uncomfortable (I'm thinking popping ears).
Welcome and good luck,
Ian.
> I appreciate all the input and advice. This is still mostly in my head
right
> now but I hope to get the CAD drawing started soon. As I get some drawing
> done I am sure I will be back to share them and ask for more input.
Thanks!
>
> Chip
> -----Original Message-----
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org]On Behalf Of Cliff Redus
> Sent: Friday, May 27, 2005 6:52 AM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Newbie needs help
>
>
> Chuck, I will put my two cents in on your design concepts.
>
> CW>Depth control will be achieved by use of inverted "wings" or air
foils,
> as in the Deep Flight subs.
>
> Inverted airfoil wing profiles were used on Deep Flight because the
boat
> was designed to be positively buoyant at all times with no variable
ballast
> tank for depth station keeping. In your design concept, you indicate that
> the sub will be adjusted manually through valves to neutral or slightly
> negative buoyancy at the surface before the dive. This sounds like you
are
> using a variable ballast tank to get neutrally buoyancy. If so, then the
> wing profiles do not need to be an inverted airfoil, as no negative lift
> force is required. Since the control surfaces are articulated, you would
> simply need the wings to have a symmetrical low drag profile.
>
> As to the concept of maintaining 1.5 ATM and using a compressed air tank
> and a regulator to supply fresh air to the cabin and then to ventilate the
> boat utilizing a compressor to purge air from the boat, I see a number of
> problems. First, compressors are very noisy and would require significant
> battery power to run the motor to drive the compressor. The load on this
> compressor would increase with depth. Why burn power on this when it is
not
> necessary? If you are planning on doing underwater flying, then you will
> need all the power can get and minimum drag to get the boat speed to a
point
> that control surfaces work. By sticking with 1 atm, all nitrogen
absorption
> issues are eliminated and thus all decompression illness issues are
> eliminated. The normal way a 1 atm boat maintains normal air composition
is
> with a CO2 scrubber in combination with O2 makeup controlled either by a
> fixed makeup flow rate or by monitoring a barometric pressure. The beauty
> of this system is that it does not require any makeup air and the
> requirement of O2 to restore the cabin environment to normal air is small.
>
> As to using FRP or steel for pressure hull, I would suggest staying with
> off the shelf pressure vessel steel like A516-70. A more aerodynamically
> clean shape can be fabricated using conical sections. The advantage of
> using a pressure hull made of steel and reinforced with stiffeners is that
> stress calculations are straight forward (see ABS rules ).
>
> Cliff
>
>
>
> From: Chuck Will
> To: personal_submersibles@psubs.org
> Sent: Thursday, May 26, 2005 3:54 PM
> Subject: [PSUBS-MAILIST] Newbie needs help
>
>
> Hello everyone,
>
>
>
> I would like to introduce myself. My name is Chip Will. First let me
> apologize for the length of this email. Just wanted to give as much info
as
> I could.
>
>
>
> I have a concept for a submersible that has been kicking around my
head
> for a few years and I am ready to start putting the design down on paper
(or
> on the computer as it is these days). What need now is some guidance from
> the souls that have gone before me.
>
>
>
> A little background on myself, and my abilities. I am a certified
Scuba
> diver (18+ years) and Scuba Instructor. I have very good mechanical
skills,
> which include some machine work, welding, and excellent electrical (low
> voltage) skills. My shop is set up with a small mill and lathe as well as
> gas and MIG welder and about every tool Sears/Craftman sells (my wife
hates
> that part).
>
>
>
> The whole idea behind this sub is to "fly" underwater. This will be a
> purely sport sub with only fun in mind. I live on Monterey Bay in
> California. We have some of the most beautiful cold water diving in the
> world. I have always wanted to be able to fly through the kelp forests.
>
>
>
> My concept is for a one person, 1 to 1.5 ATM (I'll explain this one in
a
> minute) submersible. It will have a max depth of approx 100-130 ft. It
will
> have a streamlined hull with the pilot sitting in a reclining position
with
> their head under a streamlined canopy. 4 thrusters mounted two per side,
one
> forward and one back will provide propulsion. The thrusters will be able
to
> rotate on the horizontal (pitch) axis. Two levers on either side of the
> pilot control the pitch, sort of like a tank control. Pushing the right
> lever forward will pitch one or both (selectable) right side thrusters
down,
> pulling back will pitch them up. The same with the left lever controlling
> the left thrusters. The sub will be adjusted manually through valves to
> neutral or slightly negative buoyancy at the surface before the dive.
Depth
> control will be achieved by use of inverted "wings" or air foils, as in
the
> Deep Flight subs. The wings will be mounted on the thruster rotation
shafts
> and rotate with the thrusters. I have not decided if they will be inboard
or
> outboard of the thrusters. Foot pedals will control rudders.
>
>
>
> I do not want to have to deal with CO2 scrubbers or any O2
> replenishment. I have a fear of using pure O2 in a sealed environment with
> any electrical equipment. I don't want the headaches of regulating it. I
> plan on using air from two scuba tanks, one with a standard scuba
regulator
> for emergency, and one to replenish air supply. I have an initial concept
of
> a control system that maintains the air pressure in the sub at about 1.5
> ATM. A control board would allow air to flow from the scuba tank at a set
> pressure of about 7 PSI at preset intervals. I will have to calculate the
> interval once I know the hull volume. To keep the pressure in the sub from
> getting to high, the same board will control a high volume air pump to
> discharge some of the air in the sub externally through a series of check
> valves. As fresh air is discharged into the hull interior at the front,
> stale air will be pumped out the rear. This way I can maintain the
pressure
> at roughly 1.5 ATM. That is the equivalent of about 16.5 FSW. Most scuba
> table don't even recognize that shallow of a depth as a risk for Nitrogen
> Absorption. I will have a dive computer onboard to watch for decompression
> issues. I don't see most dives going for more than an hour or two at most.
>
>
>
> That should give you a general idea of what I want to accomplish.
There
> are two things I need advise on at this stage before I go any further.
First
> is hull material. I have read a lot of opinions and seen all the hull
> calculation tables. Simple math tells me that if I want a max depth of 130
> FSW, I need to withstand absolute ATM pressure of about 72 PSI on the
hull.
> Add in a 2X safety factor (250 FSW) and the pressure increases to 130 PSI.
> My initial thought was going with a steel hull. Good strength but heavy
and
> hard to get the real streamlined hull I would like. A second thought was
> Fiberglass. If I can build a wood frame (strictly hardwoods) with
stringers
> going several directions for strength, with multiple fiberglass layers up
to
> 3/8" - ½" thick. That seems to me it would with stand the pressures at
> shallow depths. Fiberglas would allow me to work with the more streamlined
> shapes I have in mind. I would not do any of this of course without doing
> all the necessary calculations to see that it was safe. I do plan on
putting
> in an auto safety feature. If at any point the depth exceeds a preset
limit
> (probably 150 FSW) a sensor will trigger a valve to inflate an adequate
size
> lift bag that will automatically deploy and bring the sub to the surface.
>
>
>
> So.... My first question is:
>
> Should fiberglass even be considered as hull material?
>
>
>
> My second question is:
>
> What does anyone think about the air replenishment idea?
>
>
>
> Sorry for the length of this email. I figured it would save time on
> emailing questions and answers back and forth if I put as much info as I
> could in the first email.
>
>
>
> Chip Will
>
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