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From: Walter Atkinson <walter@advancedpilot.com>
Subject: Re: [LML] Re: Plugs and Mags for IVP
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Yes, a hotter, more intense spark will aid in getting the flame front=20
started.  This is *helpful* when LOP but has little effect ROP.  Once=20
started the flame front is no longer influenced by the spark intensity.=20=

  The flame front speed is unaffected by the spark intensity.

Walter


On Jan 25, 2005, at 10:07 PM, Douglas W. Johnson, MD wrote:

I certainly bow to greater authority on this.=A0 Although I suspected =
OAT=20
diff might have accounted for this, I talked to a Unison insider who=20
suggested something about better flame propagation with thier Iridium=20
plugs, and therefore more efficient burn of fuel in the cylinder.=A0=20
Would have suspected this would have raised the CHT's, however, if that=20=

were the case....
Doug
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net]On Behalf Of=20
Walter Atkinson
Sent: Tuesday, January 25, 2005 10:06 AM
To: Lancair Mailing List
Subject: [LML] Re: Plugs and Mags for IVP

Doug:

**Of interest, within the limits of my setup (VM1000, all altitude and=20=

engine parameters the same with the exception of a 15degF cooler OAT) I=20=

did notice a 20-30degF cooler CHT with the new Iridium plugs over a=20
broad range of fuel flows, and a 2-3 knot improved speed at=20
lean-of-peak operations (no change at ROP operations).**


I know of no scientific reason that the type of plug making the spark=20
could make such differences. It's more likely the OAT. More O2=20
molecules for combustion and better air cooling. The improved LOP speed=20=

is O2 increases in the cooler air. It allows for more FF at a given LOP=20=

setting. If you were to set the same FF, the HP output and TAS would be=20=

the same. We must be careful to assign the correct cause for an=20
observed change.

Walter

--Apple-Mail-1--406458010
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Yes, a hotter, more intense spark will aid in getting the flame front
started.  This is *helpful* when LOP but has little effect ROP.  Once
started the flame front is no longer influenced by the spark
intensity.  The flame front speed is unaffected by the spark intensity.


Walter



On Jan 25, 2005, at 10:07 PM, Douglas W. Johnson, MD wrote:


=
<fontfamily><param>Arial</param><color><param>0000,0000,FFFF</param><small=
er>I
certainly bow to greater authority on this.=A0 Although I suspected OAT
diff might have accounted for this, I talked to a Unison insider who
suggested something about better flame propagation with thier Iridium
plugs, and therefore more efficient burn of fuel in the cylinder.=A0
Would have suspected this would have raised the CHT's, however, if
that were the case....</smaller></color></fontfamily>

=
<fontfamily><param>Arial</param><color><param>0000,0000,FFFF</param><small=
er>Doug</smaller></color></fontfamily>

<smaller>-----Original Message-----</smaller>

<bold><smaller>From:</smaller></bold><smaller> Lancair Mailing List
[mailto:lml@lancaironline.net]<bold>On Behalf Of </bold>Walter =
Atkinson</smaller>

<bold><smaller>Sent:</smaller></bold><smaller> Tuesday, January 25,
2005 10:06 AM</smaller>

<bold><smaller>To:</smaller></bold><smaller> Lancair Mailing =
List</smaller>

<bold><smaller>Subject:</smaller></bold><smaller> [LML] Re: Plugs and
Mags for IVP</smaller>


Doug:


**Of interest, within the limits of my setup (VM1000, all altitude and
engine parameters the same with the exception of a 15degF cooler OAT)
I did notice a 20-30degF cooler CHT with the new Iridium plugs over a
broad range of fuel flows, and a 2-3 knot improved speed at
lean-of-peak operations (no change at ROP operations).**



I know of no scientific reason that the type of plug making the spark
could make such differences. It's more likely the OAT. More O2
molecules for combustion and better air cooling. The improved LOP
speed is O2 increases in the cooler air. It allows for more FF at a
given LOP setting. If you were to set the same FF, the HP output and
TAS would be the same. We must be careful to assign the correct cause
for an observed change.


Walter


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