<div dir="ltr">There was *originally* a safety concern because the Euro guys argue 42v is enough to kill you (it's a voltage limit, not a cell count limit, so even the 4.37v lipo cells at 10s are illegal). But FAI abandoned that concern when they started allowing 12 and 14s in the helicopter classes (i.e. F3C). I would argue what Billy Crystal's character said in <i>Running Scared: </i>"It's not the volts that kill you, it's the amps". A taser, as an example, delivers about 10,000v and doesn't kill you. Fundamentally if you let as little as 0.1 amps cross your chest from source to ground you begin to be at risk of death, at the very least you are going to have serious difficulty breathing. <div><br></div><div>This article reproduces what I was taught in high school: <a href="https://www.physics.ohio-state.edu/~p616/safety/fatal_current.html">https://www.physics.ohio-state.edu/~p616/safety/fatal_current.html</a></div><div><br></div><div>But that leaves aside the resistance of skin, etc. the reality is that I = V/R, so the higher the resistance of the skin the higher the voltage you can handle before allowing that 0.1 - 0.2 amps across your heart. With dry (not sweaty) hands the resistance from hand to hand (worst-case scenario of source to ground going across the chest) is 1M ohms so it would take about 20kV to get the current needed to kill, but with sweaty hands it drops to 17,000 ohms and 340V will kill you, add a wedding ring or a tool with a metal surface you are gripping tightly and the number could drop to 1000 ohms and 20V will kill, 17V would cause ventricular fibrillation. </div><div><br></div><div>In short, 42V was based on a very elementary "rule of thumb" analysis and is pretty arbitrary and makes a ton of assumptions.</div><div><br></div><div>That said, I don't think AMA rules should move to 12S until FAI rules do...</div><div><br></div><div>Peter+</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Aug 23, 2017 at 4:38 PM, Bill Polits via NSRCA-dist7 <span dir="ltr"><<a href="mailto:nsrca-dist7@lists.nsrca.org" target="_blank">nsrca-dist7@lists.nsrca.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Derek K, John G,<div><br></div><div>The only objection I have in the past heard with respect to increasing the electric power system limit to 12S is the issue of safety at the higher voltage (at least it's my impression that to some degree, safety was the reason for the original limit). I have no opinion either way, but just wanted to comment that it seems to me that a discussion of the matter of safety would be appropriate to include in the rule change proposal.</div><div><br></div><div>Best regards,</div><div><br></div><div>Bill Polits</div><div>NSCRA 4445</div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Aug 22, 2017 at 1:00 PM, <span dir="ltr"><<a href="mailto:nsrca-dist7-request@lists.nsrca.org" target="_blank">nsrca-dist7-request@lists.<wbr>nsrca.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Send NSRCA-dist7 mailing list submissions to<br>
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Today's Topics:<br>
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1. Current Rules Proposals (Derek Koopowitz)<br>
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Message: 1<br>
Date: Tue, 22 Aug 2017 10:45:11 -0700<br>
From: Derek Koopowitz <<a href="mailto:derekkoopowitz@comcast.net" target="_blank">derekkoopowitz@comcast.net</a>><br>
To: <<a href="mailto:nsrca-dist7@lists.nsrca.org" target="_blank">nsrca-dist7@lists.nsrca.org</a>><br>
Subject: [NSRCA-dist7] Current Rules Proposals<br>
Message-ID: <<a href="mailto:85A2E9C4-8753-4C3B-9E10-39AEDD3A082B@gmail.com" target="_blank">85A2E9C4-8753-4C3B-9E10-39AED<wbr>D3A082B@gmail.com</a>><br>
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Hey everyone,<br>
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It is time for me to vote on the rules proposals that are before the contest board ? I would like your input on these please. You can view the current proposals here:<br>
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<a href="http://www.modelaircraft.org/events/ruleproposals/rcaero.aspx" rel="noreferrer" target="_blank">http://www.modelaircraft.org/e<wbr>vents/ruleproposals/rcaero.asp<wbr>x</a><br>
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The cross proposals that were accepted to move on to the final vote can be seen here:<br>
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<a href="http://www.modelaircraft.org/events/ruleproposals.aspx#2018-2019" rel="noreferrer" target="_blank">http://www.modelaircraft.org/e<wbr>vents/ruleproposals.aspx#2018-<wbr>2019</a><br>
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I?d like your input by early September please. All votes need to be sent to the AMA by 9/15.<br>
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Thanks!<br>
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-Derek<br>
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</font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br><div class="m_8921951013673697519gmail_signature" data-smartmail="gmail_signature">Bill Polits<br><a href="mailto:bpolits@gmail.com" target="_blank">bpolits@gmail.com</a><br><a href="tel:(510)%20528-2341" value="+15105282341" target="_blank">510-528-2341</a><br><a href="tel:(510)%20390-1419" value="+15103901419" target="_blank">510-390-1419</a> cell</div>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Director, Fixed Wing Flight Training</div><div>Santa Clara County Model Aircraft Skypark</div><div>Associate Vice President, Academy of Model Aeronautics District X</div><div>Treasurer, National Society of Radio Control Aerobatics (NSRCA)</div><img src="http://farm8.staticflickr.com/7163/6513778381_5569cc985d_m.jpg" width="200" height="154"><img src="https://googledrive.com/host/0B4LOPeyGAgOJUVJmU1dJMVl6WWc/AcademyModelAeronauticsLogo.png" width="200" height="136"><br></div></div></div></div>
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