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I've attached the some older postings
Brent
Frank, Trouble with Bubbles, say that three times fast. I had a 55 gallon acrylic saltwater aquarium, with I believe 1/4" thick acrylic. Looking at the fish in the tank at a 45 degree angle, I didn't get to much distortion, but beyond 45 degrees, it got bad. Of course there wasn't water in front of the acrylic, but like Jay stated, using acrylic in your "V" deflector application isn't to much of a problem. Also you generally have some surface glare on aquariums unless the lights are out in the room. Looking at a couple of double pain windows in my house that are made of glass that is 3/16" to 1/4" thick, I don't see much if any distortion looking through them at a 45 degree angle. Of course that is with air on both sides so it might not be of much help. Polycarbonate like Makrolon, are generally stiffer then acrylic, so you might be able to get away with thinner sheets for your application, then using acrylic. I've been working on a sub design that requires the same basic transparent hydrodynamic fairing as you are wanting on your sub. I was planning on using polycarbonate in flat sections. I didn't need formed polycarbonate for my design. Regards, Brent Hartwig When I have troubles like bubbles on my glass, I ask my self, what would Scooby do. ; )' This reminded me of an older post in this forums archive I saved, called "Bubbles on Dome" Below I've pasted the old post. They are talking about using a product like Rain-X to make the acrylic more hydrophilic. Perhaps polycarbonate would have less trouble in this regard. I know I had this same problem with any aquarium that had been dry for a awhile. It didn't make a difference of whether they where glass or acrylic, fresh or saltwater tanks. I just had to get in there a wipe the bubbles off. Perhaps you can install windshield washers on the inside surface of the flooded acrylic fairing or never let those windows become dry. ; ) Re: [PSUBS-MAILIST] bubbles on dome
Alan, A quick google search indicates that acrylic can be either hydrophilic ( i.e., strong affinity for water) or hydrophobic (affinity for oils) . My guess is that yours is hydrophobic. You can tell by placing a drop of water on the viewport and observing if it wants to bead up ( hydrophobic) or smear out (hydrophilic). If its hydrophobic, then small micro imperfections in the acrylic viewport will contain very small air bubble that act as nucleation points for larger air bubbles. If this is so, (just a guess) then, you might be able to use a product sold to make rain water sheet on windshields. This makes the surface, at least for a while, more hydrophilic. Auto supply stores carry this type of product. Just a thought. Cliff ----- Original Message ----- From: "Alan Winick" <subguy33@yahoo.com> To: <personal_submersibles@psubs.org> Sent: Thursday, September 26, 2002 5:23 PM Subject: [PSUBS-MAILIST] bubbles on dome > OK guys, here's another one to chew on. > > I use double bow domes on Explorer. The inner dome is > flanged to the pressure hull. Covering it is a 3/8" > free-flooding dome. It's good for impact/scratch > protection and also protects the inner dome from > fingerprints and oils from the public when the sub is > on exhibit. > > Anyway, I use Novus plexiglas cleaner/polish to > maintain both domes. When I submerge, though, a > stubborn layer of air bubbles adheres to the inner > dome. Can't reach them to wipe off! Any ideas on how > to prevent this? I thought of using some sort of > surfactant, but don't want to damage the acrylic. > > Alan " End Quote Regards, Brent Hartwig
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