<html><head></head><body><p dir="ltr">You mix the foam to a designed density. Deeper foams must be denser, and hence of greater overall volume than a shallower foam for the same buoyancy. Determine your operating depth, determine the largest / lightest spheres you can get away with at that pressure, incorporate some smaller ones to fill the interstitial spaces, mix to maximum volume fraction of glass.</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On May 17, 2014 5:17:12 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="k9mail">Jim,<br />What kind of numbers are we talking here. How much volume of foam per lb of buoyancy.<br />Hank<br /><hr /><br />On Sat, 5/17/14, via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br /><br /> Subject: Re: [PSUBS-MAILIST] Gamma needs a diet<br /> To: personal_submersibles@psubs.org<br /> Received: Saturday, May 17, 2014, 7:11 PM<br /> <br /> <br /> <br /> <br /> <br /> <br /> Hank,<br /> Greatest net buoyancy on your syntactic foam is<br /> achieved by mixing larger <br /> spheres with smaller spheres so the smaller ones fit in the<br /> gaps between the <br /> larger ones.<br /> Jim<br /> <br /> <br /> In a message dated 5/17/2014 6:04:36 P.M. Central<br /> Daylight Time, <br /> personal_submersibles@psubs.org writes:<br /> Sean,<br /> Very interesting, I just googled glass microspheres and <br /> this is very <br /> doable.<br /> Hank<br /><hr /><br /> On Sat, <br /> 5/17/14, Sean T. Stevenson via Personal_Submersibles
<br /> <personal_submersibles@psubs.org> wrote:<br /> <br /> Subject: Re: <br /> [PSUBS-MAILIST] Gamma needs a diet<br /> To: "Personal Submersibles General <br /> Discussion" <personal_submersibles@psubs.org><br /> Received: Saturday, May <br /> 17, 2014, 6:34 PM<br /> <br /> Hollow<br /> glass microspheres in a (typically) epoxy <br /> matrix. The<br /> spheres are so small, they're more like a powder (for a<br /> deep <br /> / dense foam. Shallower foams will incorporate larger<br /> spheres). Mix the <br /> composite with the highest possible volume<br /> fraction of glass to <br /> resin.<br /> Sean<br /> <br /> <br /> <br /> <br /> On May 17, 2014<br /> 4:09:46 PM MDT, hank <br /> pronk via Personal_Submersibles<br /> <personal_submersibles@psubs.org> <br /> wrote:<br /> How is syntactic foam made.<br /> I once experimented with <br /> 3/4inch plastic water line (pex<br /> pipe), the stuff we plumb houses with now. <br /> I heated
the end<br /> of a piece and it melted shut nicely. So I planned <br /> to make<br /> a bunch of pipes with both ends melted shut then slide a<br /> bundle <br /> of them inside a pvc pipe. Then fill the void with<br /> poly urethane <br /> molding resin. It would be cheap and pretty<br /> tough. Perhaps an <br /> experiment is in order, unless there is a<br /> better idea out <br /> there.<br /> Hank<br /> <br /> On Fri,<br /> 5/16/14, Sean T. Stevenson via <br /> Personal_Submersibles<br /> <personal_submersibles@psubs.org> <br /> wrote:<br /> <br /> <br /> Subject: Re: [PSUBS-MAILIST] Gamma needs a diet<br /> <br /> To:<br /> "Personal Submersibles General <br /> Discussion"<br /> <personal_submersibles@psubs.org><br /> <br /> Received:<br /> Friday, May 16, 2014, 7:12 PM<br /> <br /> <br /> There's<br /> always the not-so-easy but<br /> very elegant solution <br /> of<br /> syntactic<br /> foam filled hydrodynamic
fairings. <br /> Go<br /> bigger than you<br /> need to<br /> <br /> accommodate future expansion, <br /> and compensate in the<br /> meantime<br /> with keel<br /> weight. <br /> Would improve<br /> stability, too.<br /> <br /> Sean<br /> <br /> <br /> <br /> On<br /> 2014-05-15 18:51, hank pronk via <br /> Personal_Submersibles<br /> <br /> wrote:<br /> Alan,<br /> That would work <br /> but<br /> I want to keep the sub clean on the<br /> <br /> outside. Gamma is <br /> very slippery the way it is. I<br /> am confident I can shed the <br /> weight. I have been<br /> <br /> weighing all the bits and it looks <br /> doable. I am also<br /> looking at a winter project for <br /> Gamma. I would like<br /> to<br /> have the arm, and valve and a <br /> couple of<br /> positioning <br /> thrusters on a common chassis, <br /> like<br /> the DW's. I could<br /> reduce the weight of
the<br /> lead <br /> drop weight because the entire<br /> assembly would be<br /> the drop <br /> weight. That also solves<br /> the weight<br /> problem from the <br /> batteries. I would use the<br /> <br /> original drop weight screw to <br /> drop the new assembly.<br /> Hank<br /> <br /> On Thu,<br /> 5/15/14, Alan <br /> James via Personal_Submersibles<br /> <br /> <personal_submersibles@psubs.org><br /> wrote:<br /> <br />  <br /> Subject: Re:<br /> [PSUBS-MAILIST] Gamma needs a diet<br />  To:<br /> "Personal <br /> Submersibles General Discussion"<br /> <br /> <personal_submersibles@psubs.org><br />  Received: Thursday, May <br /> 15,<br /> 2014, 8:17 PM<br />  <br />  Hank,a<br />  <br /> simple<br /> solution would be to just have a<br />  number of floats<br /> like <br /> Alec's Snoopy.He<br />  has them in a tube, but<br /> if the floats <br /> had<br /> attachment
ho!<br /> les<br />  you <br /> couldtether<br />  <br /> them & clip them on or off.Alan<br />  <br /> <br />  <br />    <br />    From: hank <br /> pronk via<br />  <br /> Personal_Submersibles<br />  <br /> <personal_submersibles@psubs.org><br />    To:<br />  <br /> personal_submersibles@psubs.org<br /> <br /> <br />    Sent: Friday,<br />  May 16, 2014 12:04 <br /> PM<br />    Subject:<br />  [PSUBS-MAILIST] Gamma needs a <br /> diet<br />  <br />    <br />  Gamma or the pilot needs <br /> to go to<br /> Jenny<br /> Craig. My new<br />  <br /> AGM batteries <br /> weigh 73 lbs each and Gamma has a<br /> 60 to 65 lb<br />  <br /> weight <br /> budget, per battery. That means Gamma<br /> needs to <br /> shed<br />  <br /> some lbs before I can take a passenger. I<br /> <br /> can switch<br />  <br /> to aluminum
scuba tanks, not sure the <br /> weight<br /> saving<br />  <br /> there. I can make an aluminum <br /> rudder and a<br /> few other<br />  <br /> parts also.<br />  <br /> Hank<br /> <br />  <br /> Personal_Submersibles mailing <br /> list<br />  <br /> Personal_Submersibles@psubs.org<br /> Â!<br /> <br /> <br /> <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br />  <br /> <br />  <br />    <br />  <br /> -----Inline Attachment <br /> Follows-----<br />  <br /> <br />  Personal_Submersibles mailing <br /> list<br />  <br /> Personal_Submersibles@psubs.org<br />  <br /> <br /> <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br />  <br /> <br /> <br /> <br /> Personal_Submersibles<br /> mailing list<br
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