Re: [PSUBS-MAILIST] Working on a new DBP design.

["John Pier" <caribsub@coqui.net>]

Hello there,
I dont receive anymore the mailing list , something s wrong?
Somebody to reply please
Herve

----- Original Message -----
From: Gary R. Boucher <protek@shreve.net>
To: <personal_submersibles@psubs.org>
Sent: Monday, March 12, 2001 9:43 AM
Subject: Re: [PSUBS-MAILIST] Working on a new DBP design.


>      Just a note to those concerned.  Syntactic foam is great if you learn
> how to use it.  That is if you mix your own.  I have some tips if anyone
is
> interested.  This foam has a tendency to form air pockets inside that you
> can not easily get rid of.  This may not be a factor at low depths but
when
> you go deeper, they may collapse.  SF should be mixed in a vacuum in such
> cases.  Flotech does sell the kits, but they DO NOT like to sell those
kits
> to people to do subs.  They would rather know that they go to use in ROVs.
>      Also, the techspheres are no longer sold (As of last summer this was
> the case) as a stand-alone product.  They still use them as filler inside
> syntactic foam.  Some had a tendency to leak.
>
> Gary Boucher
>
>
>
>
> At 07:09 AM 3/12/01, you wrote:
> >Soren,
> >
> >Here is my input, for what it's worth...
> >
> >1.  Differential thrust works well and is effective.
> >Trolling motors are designed for optimum trolling
> >speed and I haven't found them to be the most
> >responsive - I can stop and back my sub in half a
> >length using a single MinnKota 35T, but the
> >accelerations seem painfully slow.  That may cause
> >problems when going for differential thrust.
> >
> >2.  Syntactic foam is readily available - check out
> >flotec.com.  They also have "techspeheres" which are
> >plastic spheres capable of withstanding the depths you
> >are interested in.  Last time I checked, a huge box of
> >these was just over $100.  Blocks of foam are also
> >available and can be machined to shape, either by them
> >or by you.  Alternatively, you could check out
> >high-density styrofoam.  It comes in sheets and is
> >normally used for insulating homes, but it serves as a
> >dandy float.
> >
> >3.  Using plywood as a pressure vessel is a really bad
> >idea in my opinion.  Plywood is really flexible, hard
> >to join effectively, and is somewhat porous.  To build
> >something to withstand even 30 feet of depth out of
> >plywood would be an engineering feat.  Once submarine
> >I saw had two square pressure vessels built for its
> >onboard computer system - these were maybe 18 inches
> >square and about 6 inches high, custom designed and
> >built out of carbon fibre about an inch thick.  They
> >experienced severe distortion at 50 feet.  Be wary -
> >having water flow into your exposed battery
> >compartment could possibly kill you.
> >
> >4.  The depth rating of the motor depends entirely on
> >its design.  There are underwater thrusters out there
> >with a lot of power and torque, rated to 6000 feet of
> >depth, but they also carry a huge price tag.  I am
> >working on a set of low cost, high power,
> >oil-compensated, full-ocean depth thrusters with
> >intelligent motor systems because I am not happy with
> >anything else available.
> >
> >5.  Underwater connectors are pretty easy to come by -
> >I get mine from a guy in Halifax - DASCO Equipment
> >(Dave Stewart is the guy).  He reps Subconn Underwater
> >Connectors, and they are by far the best quality ones
> >I have used.  Dave overnights me connectors when I
> >need them, and his prices are lower than anywhere else
> >I have tried.  His email is dastewa@ibm.net, or you
> >can find him if you search under DASCO Equipment on
> >the net. They have big fancy catalogs that he can send
> >with all the info in them - a typical 4 pin bulkhead
> >connector and pigtailed in line connector will run you
> >$120-$150 or so.  They are pricey, but work really
> >well and are easy to use - also wet-pluggable.
> >
> >6.  No help here, sorry!
> >
> >         -Tim
> >
> >
> >
> >Hi Everybody,
> >
> >I'm new to the list, but have done some research, incl
> >searching the psubs archives, and I'm impressed with
> >what people are doing.
> >I got here after deciding to enhance my diving
> >experience by building a long range / long endurance
> >DPV.
> >I have some ideas, and would love to get some feedback
> >by all the experienced people here.
> >First, a quick overview of my ideas so far. I like the
> >principles of KISS, so my plan is the use painted
> >plywood sheets as frame construction material, and, as
> >I'm an electronics engineer, use electronic controls
> >as much as possible.
> >My target deep is abs max 200', usefull deep 130', air
> >for 3-4 hours (using 4 80cf tanks), topspeed whatever
> >I can get from std trolling motors and range 4-8 miles
> >roundtrip.
> >The basic design is when viewed from the rear:
> >o           o|
> >I   Diver   I|
> >O |I           I| O
> >         ----|-------------|----
> >O |  Batteries  | O
> >-------------|
> >
> >
> >And viewed from the side:
> >
> >        /----------------------------\
> >       /                             |
> >      /                  [  ]        |
> >     <         --------------------- |
> >      \                  [  ]        |
> >       \                             |
> >        \----------------------------/
> >
> >It's basically a H, with four electric engines 'O',
> >fixed lift on top 'o', thin variable lift tanks 'I',
> >battery box below, about where the engines are
> >located, and 4 std scuba tanks in front of the
> >batteries. The side sheets would be a 2x7' sheet, but
> >with big pieces cut out to reduce weight and improve
> >view. The 'H' mid sheet is 3' wide, where the diver
> >would lay on, would be solid from the rear and 5'
> >forward, leaving room for the diver to look down. All
> >weights will be at the bottom, and it will have wings
> >for stability during "flight". I would be designed to
> >be modular assemblies for easy transport.
> >So here comes the questions:
> >1)      I'm trying to avoid mechanics, so is it possible to
> >get good results by using only the four engines for
> >left/right and up/down control by controlling power to
> >each engine, assuming the DPV has been set for neutal
> >balance and buoyancy using the variable lift tanks ?
> >2)      I like those syntactic floats for the fixed lift,
> >are they easy to get in the shape I need (long square
> >blocks or pipes), or can I get some standard blocks I
> >can cut to shape ? And sources for normal people ?
> >3)      I would like to avoid pressure compensation, would
> >a battery box of plywood be able to withstand the
> >pressure, assuming it has internal support brackets
> >between each battery and the sealings holds ?
> >4)      Again for the engines without pressure
> >compensation, would they be able to withstand the
> >pressure if the shaft is sealed with t.ex silicone ?
> >There has been some discussion of that in the
> >archieves, but not any conclusive if no pressure
> >compensation is used. Somebody talked about that the
> >Evinrude can go deep, but I would like to use Minn
> >Kota's, as they seem to have plenty of choices at good
> >prices.
> >5)      Anybody know a good sources for the underwater
> >connectors in small quantities and low prices ?
> >6)      Sources for valves to fill and empty the variable
> >lift tanks ?
> >And any good ideas and/or sources for the tanks ?
> >
> >Regards,
> >
> >
> >Soren Kristensen
> >
> >
> >__________________________________________________
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>
>