<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div><span></span></div><div></div><div>Drag results between a model and full scale does not scale geometrically. You have to scale model and full scale off the dimensionless Reynolds number. Reynolds number scaling enables you to scale results between model and full scale using either a water tunnel or air tunnel.</div><div><br></div><div>Cliff<br><br> </div><div><br></div><div><br></div> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"> <div class="hr" style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); border-image: none; height: 0px;
line-height: 0; font-size: 0px;" contenteditable="false" readonly="true"></div> <font face="Arial" size="2"> <b><span style="font-weight: bold;">From:</span></b> Alan James via Personal_Submersibles <personal_submersibles@psubs.org><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Monday, December 29, 2014 1:55 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] model testing<br> </font> </div> <div class="y_msg_container"><br><div id="yiv4941432174"><div><div style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);"><div id="yiv4941432174yui_3_16_0_1_1419882201702_6077" dir="ltr"><span>Hank,</span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6079"
dir="ltr"><span id="yiv4941432174yui_3_16_0_1_1419882201702_6078">I just ran a test on my pressure program & you get the same crush depth</span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6080" dir="ltr"><span id="yiv4941432174yui_3_16_0_1_1419882201702_6081">on a sphere of A516-70 steel that is 1000mm diameter & 10mm thick as you</span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6080" dir="ltr"><span id="yiv4941432174yui_3_16_0_1_1419882201702_6084">do on a sphere 100mm diameter & 1mm thick.</span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6080" dir="ltr"><span id="yiv4941432174yui_3_16_0_1_1419882201702_6255">What I am not sure of is if you can scale up the drag results on a model.</span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6080" dir="ltr"><span id="yiv4941432174yui_3_16_0_1_1419882201702_7136">If you have a scale model that is 1/50th & it takes X amount of force to push
it </span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6080" dir="ltr"><span id="yiv4941432174yui_3_16_0_1_1419882201702_7141">at 3 knots, can you multiply X by 50 to get the required thrust?</span></div><div id="yiv4941432174yui_3_16_0_1_1419882201702_6080" dir="ltr"><span>Alan</span></div><br clear="none"> <div class="qtdSeparateBR"><br><br></div><div class="yiv4941432174yqt4520756702" id="yiv4941432174yqt40809"><div id="yiv4941432174yui_3_16_0_1_1419882201702_6087" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yiv4941432174yui_3_16_0_1_1419882201702_6086" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yiv4941432174yui_3_16_0_1_1419882201702_6085" dir="ltr"> <div class="hr" style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); border-image: none; height: 0px;
line-height: 0; font-size: 0px;" contenteditable="false" readonly="true"></div> <font id="yiv4941432174yui_3_16_0_1_1419882201702_6088" face="Arial" size="2"> <b><span style="font-weight: bold;">From:</span></b> Brian Cox via Personal_Submersibles <personal_submersibles@psubs.org><br clear="none"> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br clear="none"> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, December 30, 2014 8:43 AM<br clear="none"> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] model testing<br clear="none"> </font> </div> <div class="yiv4941432174y_msg_container" id="yiv4941432174yui_3_16_0_1_1419882201702_7142"><br clear="none">Hank,<br clear="none"> I would say no. It would have to be so exact that it would be virtually impossible to extrapolate from the small model, and
aside from that I think there are other engineering principles involved that would come into play , Sean would be the person to ask ! I know that it is done in wave tanks and wind tunnels, but in those you are looking at laminar flow and such things, not structural strength so much. You might be able to get a rough idea of how it would start to collapse maybe. The larger the model the better I would think.<br clear="none"><br clear="none">Brian<br clear="none"><br clear="none">--- <a id="yiv4941432174yui_3_16_0_1_1419882201702_7143" href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> wrote:<br clear="none"><br clear="none">From: hank pronk via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect"
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">To: <a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">Subject: [PSUBS-MAILIST] model testing<br clear="none">Date: Mon, 29 Dec 2014 10:52:46 -0800<br clear="none"><br clear="none">Hi all<br clear="none">If you make a scale model of a submarine in complete detail. Scale the size and metal thickness, is it a reasonable representation of depth capabilities when pressure tested?<br clear="none">Hank<br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a href="mailto:Personal_Submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br
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