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Date: Mon, 8 Oct 2012 19:06:33 -0700
Message-ID: <CAOFHbnr4ZaeR04VjLx8tDTjukyyOp0wbs8FK0R9N=qa05WVq4Q@mail.gmail.com>
Subject: Re: [FlyRotary] Re: colder spark plugs
From: David Leonard <wdleonard@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Hi Earnest,
I like were you are going with the idea of a heat sink, but I am not sure
that I could come up with a better design for a spark plug.  After all, it
is a miracle that we have a substance that has high thermal conducitivity
with very low electrical conductivity and is also strong enough to stand up
to combustion pressures.  A lot of smart people have put a lot of time an
effort into spark plug design and I am pretty sure I wouldn't be able to
improve on it.  Besides, that is the whole point of using a colder plug, it
is kinda like having a heat sink.

 --
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net


On Mon, Oct 8, 2012 at 10:25 AM, Ernest Chrisltey <echristley@att.net>wrote:

>  On 10/08/2012 01:11 PM, Steven W. Boese wrote:
>
>
> It's my opinion that heat sinks or sources on the insulator on the spark
> plug wire side would have minimal effect on the temperature of the
> electrode tip.  The proof, of course, would be to try it and see.  I would
> encourage you to do so.
>
>
>
> I was encouraged by the statement in the link I provided that the temp
> difference in a hot and cold plug was 10*C to 20*C.  My supposition (hard
> to even call it a hypothesis at this point), is that those experiencing SAG
> are riding on the ragged edge.  Pulling just a little more heat out of the
> plug would be enough to make them last dependably.
>
> How about this for an experimental setup.  Fit the engine leading plugs
> with spark-plug CHT probes.  Fashion a heat sink for just one of the LE
> plugs.  Monitor the temps, and cut the plugs open after 25hrs, looking for
> the deterioration you noted in the first installment.
>
> Sounds like an experiment to run, just as soon as I start flying.
>

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<div>Hi Earnest,</div>
<div>I like were you are going with the idea of a heat sink, but I am not s=
ure that I could come up with a better design for a spark plug.=A0 After al=
l, it is a miracle that we have a substance that has high thermal conduciti=
vity with very low electrical conductivity and is also strong enough to sta=
nd up to combustion pressures.=A0 A lot of smart people have put a lot of t=
ime an effort=A0into spark plug design and I am pretty sure I wouldn&#39;t =
be able to improve=A0on it.=A0 Besides, that is=A0the whole point of using =
a colder plug, it is kinda like having a heat sink.</div>

<div>=A0</div>
<div>=A0-- <br>David Leonard<br><br>Turbo Rotary RV-6 N4VY<br><a href=3D"ht=
tp://N4VY.RotaryRoster.net">http://N4VY.RotaryRoster.net</a><br><a href=3D"=
http://RotaryRoster.net">http://RotaryRoster.net</a><br><br><br></div>
<div class=3D"gmail_quote">On Mon, Oct 8, 2012 at 10:25 AM, Ernest Chrislte=
y <span dir=3D"ltr">&lt;<a href=3D"mailto:echristley@att.net" target=3D"_bl=
ank">echristley@att.net</a>&gt;</span> wrote:<br>
<blockquote style=3D"BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PA=
DDING-LEFT:1ex" class=3D"gmail_quote">
<div bgcolor=3D"#FFFFFF" text=3D"#000000">
<div class=3D"im">
<div>On 10/08/2012 01:11 PM, Steven W. Boese wrote:<br></div>
<blockquote type=3D"cite">
<div style=3D"FONT-FAMILY:Tahoma;DIRECTION:ltr;FONT-SIZE:10pt"><br>
<p>It&#39;s my opinion that heat sinks or sources on the insulator on the s=
park plug wire side would have minimal effect on the temperature of the ele=
ctrode tip.=A0 The proof, of course, would be to try it and see.=A0 I would=
 encourage you to do so.</p>

<p>=A0</p><br></div></blockquote></div>I was encouraged by the statement in=
 the link I provided that the temp difference in a hot and cold plug was 10=
*C to 20*C.=A0 My supposition (hard to even call it a hypothesis at this po=
int), is that those experiencing SAG are riding on the ragged edge.=A0 Pull=
ing just a little more heat out of the plug would be enough to make them la=
st dependably.<br>
<br>How about this for an experimental setup.=A0 Fit the engine leading plu=
gs with spark-plug CHT probes.=A0 Fashion a heat sink for just one of the L=
E plugs.=A0 Monitor the temps, and cut the plugs open after 25hrs, looking =
for the deterioration you noted in the first installment.<br>
<br>Sounds like an experiment to run, just as soon as I start flying.<br></=
div></blockquote></div><br><br clear=3D"all"><br>

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