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Hi
Rick,
Acrylic (Polymethyl Methacylate) has been studied very
thouroughly by the Navy and many other manufacturers. There is plenty of data
available on Acrylyc applications for underwater vehicles which is extremely
reliable. I assume that there is no such data for Polycarbonate yet.
According to the Handbook of Acrylics fro Submersibles,
Hyperbaric Chambers and Aquaria by Jerry D. Stachiw (Published by the Marine
Technology Society) and I quote:
"There
are six attributes and acceptable material must have, ranked in order of
importance,
They
are:
- Reproducibility of the material's response to
identical load conditions.
- Predicatability of the material's response to
different loading conditions.
- Availability of test criteria for establishing
and maintaining quality assurance and control procedures during
fabrication.
- Accesibility to proven design
criteria for the particular material.
- Availability of fabrication technology capable of
producing large-scale spherical shells and shell sectors free of
residual tensile stresses with the same physical properties as small-scale
models.
- Low
fabrication costs."
Hugo
I was given a demonstration today of how acrylic
(Plexiglas) fails compared to polycarbonate (Lexan). It fails
suddenly and catastrophically.
Is there any reason not to use polycarbonate
instead? Much more expensive, but, according to the staff member of the
plastics company who did the demo, it's about 100 times stronger than acrylic
and much more flexible. Other than not being as scratch resistant, is
there any other technical reason not to use poly?
Rick L
Vancouver, Canada
----- Original Message -----
Sent: Thursday, January 26, 2006 12:41
PM
Subject: RE: [PSUBS-MAILIST] Electric
PSUB
Michael,
You made a good start with R/Csubs and reading. I shall
give some awnsers an commets to your questions.
At the list is steel the material of choise for
reliability and ageing reson
60m operating depth
100m crush depth MAX (where I will run it
(fresh water) won't be deeper than that)
[Emile D.L.van Essen] for these depths a safety factor of 2+ is
common
1 ATM
Fast
[Emile D.L.van Essen] Why?
Electric
Cheap as possible
'Trailerable'
No compressed air/CO2 absorbants
[Emile D.L.van
Essen] Ballast control should be done with compressed air. A life support
system is easyer and cheaper than yoiu
think.
Inside I want a seat, can't be doing with lying
on my front.
Ideally 1 man operation for in/out the water -
(Think that's all)
It needs to be as cheap as possible,
however obviously I don't want to endanger my life. So I was thinking about
CCTV cameras on the outside in pressure housing, with a array of monitors on
the inside. Any thoughts? Things I thought about : Increased temperature
and battery draw. This would however, allow me to bypass the acrylic dome
aspect.
[Emile D.L.van
Essen] I can help you with a dome (580 mm O.D. @ 30 mm thick) The
view is worth it!
Propulsion. I have a 2HP (36V) electric
motor left over from another project, now would this be enough to propel me
through the water at a reasonable speed? Not sure if you call it dynamic
diving (use of hydroplanes to dive) but that is what I was thinking and so
will need some speed.
[Emile D.L.van Essen] You can make a R/C sub slightly
buoyant and you can dibe dynamic. A psub need freeboard . Ballast tanks should
have 20-30 % boats volume; that dont dive with
2 HP.
The other thing that I always try to aim
for when I made subs in the past, was to make battery power the only limiting
factor. So things like CO2 absorbant/air scrubbers need to be 'bypassed'. I
was thinking about changing the air every 10? minutes so as to eliminate this
problem (open hatch, nothing fancy). Anyone see a problem with this?[Emile D.L.van Essen] As
said, a LSS is not so difficult but a internal space of 500 liter gives a safe
dive time of 1/2 hour. You can use dive gear for
emergency.
Groet,
Emile
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