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From: "paul" <sqpilot@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-554869@logan.com>
Subject: Re: [FlyRotary] Re: (unshrouded plug ?)required wrench
Date: Fri, 3 Dec 2004 19:26:02 -0600
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Very useful information, Bill.  I now have a much better understanding =
of the relationship of the plugs to the wires and the ignition system.  =
Thanks for thaking the time to write/send it.  Paul Conner, hoping for =
DAR inspection the first of the week.
  ----- Original Message -----=20
  From: Bill Dube=20
  To: Rotary motors in aircraft=20
  Sent: Friday, December 03, 2004 10:15 AM
  Subject: [FlyRotary] Re: (unshrouded plug ?)required wrench



    They should work fine.  I just felt that for a system set up for =
maximum spark power, I didn't want to have a big resistance in the plug. =
 I have no idea whether you would ever notice the difference.  I expect =
Paul Yaw would.

          The resistor is there as a "ballast" to limit the peak =
current. You need high voltage to strike the arc, but once the arc has =
formed, the resistance across it is low and it takes very little voltage =
to sustain it. Without the resistor in the plug, very high current =
flows, eroding the electrode and shortening the life of the plug. Also, =
the high current produces a high magnetic field, causing radio =
interference.=20

          The resistor also helps to increase the duration of the spark. =
There is a fixed amount of energy stored in the coil for each spark. =
Without the resistor, a high current flows. The energy is then quickly =
spent, resulting in a shorter spark duration.

          Additionally, you can "burn out" some types of spark plug =
wires by using non-resistor spark plugs. The wire can't handle the extra =
current and goes open-circuit.=20

          Most cars have "magnetic suppression" type spark plug wire =
these days. It is a long coil of thin wire wrapped around insulating =
fibers. It acts as an inductor in the circuit. This tends to make the =
current much more constant during each spark.=20

          With electronic ignition, it is not uncommon to have both =
magnetic suppression wire AND resistor plugs. They act in concert to =
limit peak current, to smooth out the average current, and to reduce =
radio (and computer) interference.=20

          If the coils and ignition control module you have selected =
were designed to use magnetic suppression wires and resistor plugs, you =
would probably be smart in continuing to use these type plugs and wires. =
The higher peak current from non-resistor plugs can also damage the coil =
or ICM if they are not designed for that use.=20

          Just my eight cents. :^)


>>  Homepage:  http://www.flyrotary.com/

>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html

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<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>Very useful information, Bill.&nbsp; I =
now have a=20
much better understanding of the relationship of the plugs to the wires =
and the=20
ignition system.&nbsp; Thanks for thaking the time to write/send =
it.&nbsp; Paul=20
Conner, hoping for DAR inspection the first of the week.</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A title=3Dbdube@al.noaa.gov href=3D"mailto:bdube@al.noaa.gov">Bill =
Dube</A>=20
</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dflyrotary@lancaironline.net=20
  href=3D"mailto:flyrotary@lancaironline.net">Rotary motors in =
aircraft</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Friday, December 03, 2004 =
10:15=20
  AM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [FlyRotary] Re: =
(unshrouded plug=20
  ?)required wrench</DIV>
  <DIV><BR></DIV>
  <BLOCKQUOTE class=3Dcite cite=3D"" type=3D"cite"><BR><FONT =
face=3Dverdana=20
    size=3D2>They should work fine.&nbsp; I just felt that for a system =
set up for=20
    maximum spark power, I didn't want to have a big resistance in the=20
    plug.&nbsp; I have no idea whether you would ever notice the=20
    difference.&nbsp; I expect Paul Yaw would.</FONT></BLOCKQUOTE><FONT=20
  =
face=3Dverdana><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp=
;</X-TAB>The=20
  resistor is there as a "ballast" to limit the peak current. You need =
high=20
  voltage to strike the arc, but once the arc has formed, the resistance =
across=20
  it is low and it takes very little voltage to sustain it. Without the =
resistor=20
  in the plug, very high current flows, eroding the electrode and =
shortening the=20
  life of the plug. Also, the high current produces a high magnetic =
field,=20
  causing radio interference.=20
  =
<BR><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</X-TAB>Th=
e=20
  resistor also helps to increase the duration of the spark. There is a =
fixed=20
  amount of energy stored in the coil for each spark. Without the =
resistor, a=20
  high current flows. The energy is then quickly spent, resulting in a =
shorter=20
  spark=20
  =
duration.<BR><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<=
/X-TAB>Additionally,=20
  you can "burn out" some types of spark plug wires by using =
non-resistor spark=20
  plugs. The wire can't handle the extra current and goes open-circuit.=20
  =
<BR><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</X-TAB>Mo=
st=20
  cars have "magnetic suppression" type spark plug wire these days. It =
is a long=20
  coil of thin wire wrapped around insulating fibers. It acts as an =
inductor in=20
  the circuit. This tends to make the current much more constant during =
each=20
  spark.=20
  =
<BR><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</X-TAB>Wi=
th=20
  electronic ignition, it is not uncommon to have both magnetic =
suppression wire=20
  AND resistor plugs. They act in concert to limit peak current, to =
smooth out=20
  the average current, and to reduce radio (and computer) interference.=20
  =
<BR><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</X-TAB>If=
 the=20
  coils and ignition control module you have selected were designed to =
use=20
  magnetic suppression wires and resistor plugs, you would probably be =
smart in=20
  continuing to use these type plugs and wires. The higher peak current =
from=20
  non-resistor plugs can also damage the coil or ICM if they are not =
designed=20
  for that use.=20
  =
<BR><BR><X-TAB>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</X-TAB>Ju=
st my=20
  eight cents. :^)<BR></FONT>
  <P><PRE>&gt;&gt;  Homepage:  http://www.flyrotary.com/

&gt;&gt;  Archive:   http://lancaironline.net/lists/flyrotary/List.html
</PRE></BLOCKQUOTE></BODY></HTML>

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