[NSRCA-dist7] NSRCA-dist7 Digest, Vol 99, Issue 3 [RCA 18-09 - 12S Voltage]

Wed Aug 23 17:45:26 AKDT 2017

I agree with Peter's analysis about the safety issues.

I do not agree that the FAI should have any bearing on what we do about 
this rule proposal. It is not enforced at the local level nor at the 
Nats. I have heard that the high voltage lipos were used at the Nats 
this year fully charged. If the rule is disregarded and there is not a 
safety issue, why not increase the limit to encourage innovation, reduce 
costs and improve the longevity of our equipment? See Jeff Worsham's 
article on rule proposals in the June 2017 K-Factor.

We might even demonstrate to the FAI that there is no downside to a 
voltage increase. The rule proposal does require that F3A at the Nats 
uses the FAI voltage rule in team selection years, just as it does for 
the sound rules. Probably won't be checked anyway.

John Gayer

Contest Board District 8 and submitter of the voltage rule proposal

On 8/23/2017 5:56 PM, Peter Vogel via NSRCA-dist7 wrote:
> 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 /Running Scared: /"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.
>
> This article reproduces what I was taught in high school: 
> https://www.physics.ohio-state.edu/~p616/safety/fatal_current.html 
> <https://www.physics.ohio-state.edu/%7Ep616/safety/fatal_current.html>
>
> 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.
>
> In short, 42V was based on a very elementary "rule of thumb" analysis 
> and is pretty arbitrary and makes a ton of assumptions.
>
> That said, I don't think AMA rules should move to 12S until FAI rules 
> do...
>
> Peter+
>
> On Wed, Aug 23, 2017 at 4:38 PM, Bill Polits via NSRCA-dist7 
> <nsrca-dist7 at lists.nsrca.org <mailto:nsrca-dist7 at lists.nsrca.org>> wrote:
>
>     Derek K, John G,
>
>     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.
>
>     Best regards,
>
>     Bill Polits
>     NSCRA 4445
>
>     On Tue, Aug 22, 2017 at 1:00 PM,
>     <nsrca-dist7-request at lists.nsrca.org
>     <mailto:nsrca-dist7-request at lists.nsrca.org>> wrote:
>
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>         Today's Topics:
>
>            1. Current Rules Proposals (Derek Koopowitz)
>
>
>         ----------------------------------------------------------------------
>
>         Message: 1
>         Date: Tue, 22 Aug 2017 10:45:11 -0700
>         From: Derek Koopowitz <derekkoopowitz at comcast.net
>         <mailto:derekkoopowitz at comcast.net>>
>         To: <nsrca-dist7 at lists.nsrca.org
>         <mailto:nsrca-dist7 at lists.nsrca.org>>
>         Subject: [NSRCA-dist7] Current Rules Proposals
>         Message-ID: <85A2E9C4-8753-4C3B-9E10-39AEDD3A082B at gmail.com
>         <mailto:85A2E9C4-8753-4C3B-9E10-39AEDD3A082B at gmail.com>>
>         Content-Type: text/plain; charset="utf-8"
>
>
>
>
>
>
>
>         Hey everyone,
>
>
>
>         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:
>
>
>
>         http://www.modelaircraft.org/events/ruleproposals/rcaero.aspx
>         <http://www.modelaircraft.org/events/ruleproposals/rcaero.aspx>
>
>
>
>         The cross proposals that were accepted to move on to the final
>         vote can be seen here:
>
>
>
>         http://www.modelaircraft.org/events/ruleproposals.aspx#2018-2019
>         <http://www.modelaircraft.org/events/ruleproposals.aspx#2018-2019>
>
>
>
>         I?d like your input by early September please.  All votes need
>         to be sent to the AMA by 9/15.
>
>
>
>         Thanks!
>
>         -Derek
>
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>         End of NSRCA-dist7 Digest, Vol 99, Issue 3
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>
>     -- 
>     Bill Polits
>     bpolits at gmail.com <mailto:bpolits at gmail.com>
>     510-528-2341 <tel:%28510%29%20528-2341>
>     510-390-1419 <tel:%28510%29%20390-1419> cell
>
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>
> -- 
> Director, Fixed Wing Flight Training
> Santa Clara County Model Aircraft Skypark
> Associate Vice President, Academy of Model Aeronautics District X
> Treasurer, National Society of Radio Control Aerobatics (NSRCA)
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