X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4487551 for flyrotary@lancaironline.net; Thu, 30 Sep 2010 11:40:43 -0400 Received-SPF: pass receiver=logan.com; client-ip=71.74.56.124; envelope-from=clouduster@austin.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=exbvkCqEOBXDkHq+8n3wanotOBQtbe7qbIajSD+JluU= c=1 sm=0 a=_BDd92krOsoA:10 a=04I7FWNrTfP4RHm++yk/MQ==:17 a=Ia-xEzejAAAA:8 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=r1ClD_H3AAAA:8 a=1VPSJWL81OYIGZMbWewA:9 a=pm_L0RJVrTo_iCSE3BcA:7 a=Zi6gmNtPYMExY9ZP4UWI4NpQuWoA:4 a=wPNLvfGTeEIA:10 a=EzXvWhQp4_cA:10 a=a9_u9vxst1qhxZsp:21 a=gJW7kK0Q3IkwJGB-:21 a=pedpZTtsAAAA:8 a=LaPdxsmrjhDds9Z9GJ8A:9 a=UAYpXs02PRKZjBJoAMIA:7 a=R0Zv149VQ23SE2KgCXiqN8zJk_MA:4 a=eJojReuL3h0A:10 a=x_eBuYnr7MDau9Jb:21 a=SzXL89pWmHQAShC6:21 a=04I7FWNrTfP4RHm++yk/MQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 70.113.14.52 Received: from [70.113.14.52] ([70.113.14.52:55709] helo=DWHPC) by hrndva-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id B8/C5-07458-35FA4AC4; Thu, 30 Sep 2010 15:40:06 +0000 Message-ID: <0ABD9B969D504F0A86ED22D0B0E68C90@DWHPC> From: "Dennis Havarlah" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: New SAG Theory Discussions of SAG Date: Thu, 30 Sep 2010 10:40:01 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_025E_01CB608B.D6106370" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18197 This is a multi-part message in MIME format. ------=_NextPart_000_025E_01CB608B.D6106370 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I have had great success with the iriduim plugs that are OEM in the = Renesis - My first set were driven in the car about 10,000 miles. I = used these original plugs for 240 flying hours without any SAG using = Mogas and 100LL. After 250 hours I replaced the plugs with new ones = and did not see any change in engine performance. I think Tracy used = the same type plugs several hundred hours in his Renesis powered RV-4 = without any SAG problems. Both of these aircraft used Mogas most of = the time. I use 100 LL when I can't get Mogas. Renesis OEM Plugs are NGK Brand. RE9B - T RE7C - L=20 Dennis H. ----- Original Message -----=20 From: Steven W. Boese=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 30, 2010 10:14 AM Subject: [FlyRotary] Re: New SAG Theory Discussions of SAG Ed, You take good notes. Just a couple of clarifications: The decrease in the thermal = conductivity of the copper core may be the result of thermal cycling = causing development of porosity within the copper. This is independent = of the corrosion going on between the Mn alloy electrode sheath and the = insulator. So there are two essentially independent mechanisms = contributing to the heat range change of the spark plug with age. =20 The development of the porosity within the copper is not particularly = affected by the type of fuel whereas the corrosion between the Mn alloy = sheath and the insulator is accelerated by the use of 100LL. The cure is still to install new spark plugs. =20 I have colder spark plugs from Racing Beat that are recommended for = prolonged use in high RPM high power applications. At best, the colder = plugs will merely delay the onset of SAG but won't prevent it from = happening eventually. It will be some time before the results of using = those plugs will be known. Steve Boese =20 -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [flyrotary@lancaironline.net] On = Behalf Of Ed Anderson [eanderson@carolina.rr.com] Sent: Thursday, September 30, 2010 8:46 AM To: Rotary motors in aircraft Subject: [FlyRotary] New SAG Theory Discussions of SAG In a nut shell, Steve's excellent data gathering (how many of use have = access to a scanning electron microscope or spectrum analyzer {:>)) and = analysis indicates a possible alternative reason for SAG other than = fouling.=20 It basically boils down to a theory of pre-ignition based on the = deteorating heat removal capacity of the plug. =20 There is a copper core (the photos showing the two cores) in the = center of the ceramic cone which is responsible for conducting 90% of = the heat away from the center electrode. Based on Steve's' electron = microscope viewing of two cores (one new and one having been used in a = 100LL environment), it appears that the plug using leaded gasoline has = corrosion occurring on the boundary between this copper core and the = surrounding (hot) elements. This layer of corrosion hinders heat = removal from the plug leading to parts of the plug becoming hot enough = to trigger pre-ignition. This SAG tends to happened at high power settings and reducing power = tends to make it go away (for a while). Steve's theory is that the plug = encounters max heat and temperature at high power settings and that = reducing the power permits the plug to cool off enough for the = pre-ignition to go away (for a while). So we now have two theories - one is the fouled plug and one of the = overheated plug causing SAG. Preignition generally leads to detonation = which does not appear to be happening (at least no one is finding the = typical detonation damage to the rotary engine). A possible reason is = the quenching effect of the less than optimum shape of the rotary = combustion space may tend to delay or prevent the onset of detonation = damage that one would expect from continuous preignition caused by a too = hot plug. I believe Steve intends to see if he can find some colder plugs (the = ones that conduct heat better) and see if that extends the time between = SAG. Currently I find that roughly 25-30 hours is about the max I can = get using 100LL before SAG sets in, whereas Tracy and others have well = over 150 hours using unleaded Mogas. So if the colder plugs extend the = time before SAG, I would say that pretty much would suggest Steve's = theory is correct - if Not, then perhaps the fouled Plug theory still = has merit or it could be some other phenomena happening. Steve, my apologies if I did not present your case as well as you = could Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com . From: Bill Bradburry=20 Sent: Thursday, September 30, 2010 9:59 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Discussions of SAG I understand that there was a presentation on SAG at the meeting. Can = someone go over the alternative theory with the ones of us that were not = in attendance? It looked like someone had a scanning electron = microscope photo that they were showing! Wow! Are we getting = sophisticated or what!! Was this an explanation of the cause, or ideas = for prevention, both?? Bill B ------=_NextPart_000_025E_01CB608B.D6106370 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I have had great success with the = iriduim plugs=20 that are OEM in the Renesis - My first set were driven in the car about = 10,000=20 miles.  I used these original plugs for 240 flying hours without = any SAG=20 using Mogas and 100LL.   After 250 hours I replaced the plugs = with new=20 ones and did not see any change in engine performance.   I=20 think Tracy used the same type plugs several = hundred hours in his=20 Renesis powered RV-4 without any SAG problems.   Both of these = aircraft used Mogas most of the time.  I use 100 LL when I = can't get=20 Mogas.
 
Renesis OEM Plugs are NGK = Brand.
RE9B - T
RE7C - L 
 
Dennis H.
----- Original Message -----
From:=20 Steven W. = Boese=20
Sent: Thursday, September 30, = 2010 10:14=20 AM
Subject: [FlyRotary] Re: New = SAG Theory=20 Discussions of SAG

Ed,
 
You take good notes.
 
Just a couple of = clarifications:  The=20 decrease in the thermal conductivity of the copper core may be the = result of=20 thermal cycling causing development of porosity within the = copper. =20 This is independent of the corrosion going on between the Mn = alloy=20 electrode sheath and the insulator.  So there are two essentially = independent mechanisms contributing to the heat range change of the = spark plug=20 with age. 
 
The development of the porosity = within the=20 copper is not particularly affected by the type of fuel whereas the = corrosion=20 between the Mn alloy sheath and the insulator is accelerated by = the use=20 of 100LL.
 
The cure is = still to install=20 new spark plugs. 
 
I have colder = spark plugs from=20 Racing Beat that are recommended for prolonged use in high RPM = high power=20 applications.  At best, the colder plugs will merely delay the = onset of=20 SAG but won't prevent it from happening eventually.  It will = be some=20 time before the results of using those plugs will be=20 known.
 
Steve Boese
 
  
 
From: Rotary = motors in aircraft=20 [flyrotary@lancaironline.net] On Behalf Of Ed Anderson=20 [eanderson@carolina.rr.com]
Sent: Thursday, September 30, = 2010 8:46=20 AM
To: Rotary motors in aircraft
Subject: = [FlyRotary] New=20 SAG Theory Discussions of SAG

In a nut shell, Steve's excellent data = gathering (how=20 many of use have access to a scanning electron microscope or spectrum = analyzer=20 {:>)) and analysis indicates a possible alternative reason for SAG = other=20 than fouling. 
 
 It basically boils down to a theory of=20 pre-ignition based on the deteorating heat removal capacity of the = plug. =20
 
There is a copper core (the photos showing the = two=20 cores) in the center of the ceramic cone which is responsible for = conducting=20 90% of the heat away from the center electrode.  Based on = Steve's'=20 electron microscope viewing of two cores (one new and one having been = used in=20 a 100LL environment), it appears that the plug using leaded gasoline = has=20 corrosion occurring on the boundary between this copper core and the=20 surrounding (hot) elements.  This layer of corrosion hinders heat = removal=20 from the plug leading to parts of the plug becoming hot enough to = trigger=20 pre-ignition.
 
This SAG tends to happened at high power = settings and=20 reducing power tends to make it go away (for a while).  Steve's = theory is=20 that the plug encounters max heat and temperature at high power = settings and=20 that reducing the power permits the plug to cool off enough for the=20 pre-ignition to go away (for a while).
 
So we now have two theories - one is the = fouled plug and=20 one of the overheated plug causing SAG.  Preignition generally = leads to=20 detonation which does not appear to be happening (at least no one is = finding=20 the typical detonation damage to the rotary engine).  A possible = reason=20 is the quenching effect of the less than optimum shape of the rotary=20 combustion space may tend to delay or prevent the onset of detonation = damage=20 that one would expect from continuous preignition caused by a too hot=20 plug.
 
I believe Steve intends to see if he can find = some=20 colder plugs (the ones that conduct heat better) and see if that = extends the=20 time between SAG.  Currently I find that roughly 25-30 hours is = about the=20 max I can get using 100LL before SAG sets in, whereas Tracy and others = have=20 well over 150 hours using unleaded Mogas.  So if the colder plugs = extend=20 the time before SAG, I would say that pretty much would suggest = Steve's theory=20 is correct - if Not, then perhaps the fouled Plug theory still has = merit or it=20 could be some other phenomena happening.
 
Steve, my apologies if I did not present your = case as=20 well as you could
 
Ed
 
Edward L. Anderson
Anderson Electronic = Enterprises=20 LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com
 
.
 
 

Sent: Thursday, September 30, 2010 9:59 AM
Subject: [FlyRotary] Discussions of SAG

I = understand that=20 there was a presentation on SAG at the meeting.  Can someone go = over the=20 alternative theory with the ones of us that were not in = attendance?  It=20 looked like someone had a scanning electron microscope photo that they = were=20 showing!  Wow!  Are we getting sophisticated or what!!  = Was=20 this an explanation of the cause, or ideas for prevention,=20 both??

 

Bill=20 B

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