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Re: [PSUBS-MAILIST] acrylic vs polycarbonate

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
 

1 man
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