X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3748519 for flyrotary@lancaironline.net; Tue, 07 Jul 2009 18:17:48 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (sv1-1.per.aanet.com.au [203.24.100.68]) by poplet2.per.eftel.com (Postfix) with ESMTP id 8BA51173853 for ; Wed, 8 Jul 2009 06:17:08 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id DA6EFBEC013 for ; Wed, 8 Jul 2009 06:17:03 +0800 (WST) Message-ID: <86EF7DE689034929B708BA6CD317FA8F@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: SAG was: [FlyRotary] Re: Muffler Date: Wed, 8 Jul 2009 08:17:07 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00DF_01C9FFA4.7C074360" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 090707-0, 07/07/2009), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_00DF_01C9FFA4.7C074360 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ed, Would arsenic have any effect on lead, I know it dissolves some soft = metals. George ( down under) Hi Jeff, =20 Oh, I don't throw them out - I have a bushel basket of used plugs. = But, you are right they are around $5.00 down here when purchased in = bulk/box. =20 The 3 electrode ground shields the ceramic cone from the typical = abrasive blasting pretty well. Make it a pain to clean the stock plugs, = but they certainly do not have any noticeable wear after 25 hours so I = save them. =20 =20 I tried several methods - but despite what the gun shops advertise = there is no solvent for lead short of foaming nitric acid (or something = equally hazardous). =20 I believe that if someone had a powerful ultrasonic cleaning machine = that placing them in a solution of alcohol or something similar and = using ultra sound to blast the lead crystals off the ceramic might do = the job. But, that is one device I do not have. =20 But, you never know when one may appear on ebay for $5.00 {:>) =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Jeff Whaley Sent: Tuesday, July 07, 2009 12:44 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: SAG was: [FlyRotary] Re: Muffler =20 Hey Ed, now might be the time you cleaned a few SAG plugs and tested = them? It seems hard to believe that plugs need be thrown out after 25 hours. BTW, up here in Ottawa, I had to pay $17 each ($68 per set) for stock = Mazda plugs, on a trip south I picked up some in Ogdensburg NY around $5 = each. Jeff =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Ed Anderson Sent: Tuesday, July 07, 2009 7:10 AM To: Rotary motors in aircraft Subject: [FlyRotary] SAG was: [FlyRotary] Re: Muffler =20 There are undoubtedly numerous possibilities as to what is = happening/causing SAG. However, two things are very clear: =20 1.. 100 LL does definitely reduce the time spark plugs can be used = before SAG occurs. The nominal time period that I have found in my = engine is 24-30 hours. You can take the plug out and examine the = ceramic cone and see the glint of what I believe (but have not done a = chemical analysis) of lead crystals. Folks using MOGAS (such as Tracy) = have reported going over 150 hours without SAG. So I do believe there = is a connection between 100LL and the short interval of use before SAG.=20 =20 I even attempted to use TCP which is used in some aircraft engines and = is reportedly suppose to reduce lead deposits. It simply make the = problem worst, but upon further research I discovered that for this = chemical to work the cylinder head temperature has to be much higher = than what our water cooled sparkplugs typically see. In my case, the = chemical caused further deposits (of some sort) on the sparkplug and I = barely got 5 hours out of the set I used. This may in part explain why = our sparkplugs seem to foul more with 100LL than aircraft sparkplugs - = they don't get hot enough? =20 =20 2.. If you encounter SAG, then replacing the sparkplugs immediately = eliminates the SAG problem (for a period of time). =20 =20 So both of those factors lead me to believe it is fouling of spark = plugs rather than pre-ignition. If pre-ignition then my dozens of times = of SAG (like every 15 minutes on the 5 hour trip from Louisiana) would = surely have resulted in damage to the engine. =20 =20 In any case, whatever the cause, since I have been replacing my = sparkplugs regularly at 25-30 hour intervals I have encountered no SAG. = YMMV =20 Ed =20 =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of William Wilson Sent: Tuesday, July 07, 2009 12:09 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Muffler =20 While the rotary design is a little more resistant to the onset of = preignition, once it happens, the rotary is damaged just as easily as a = piston engine or even more so. Drag racers suffering preignition have = dismantled their motors and found rotors dented in from excess chamber = pressure. It is possible that you have been having mild preignition not = enough to damage the engine, I suppose. Do you suppose you have been = running really excessively rich? That would also contribute to plug = fouling, low power and low EGT. If you have fuel injection, a fuel map = problem showing up only at high manifold pressures (higher than you = normally attain in your usual operating regime) maybe? You should get = WAY more than 10 hours on spark plugs even running 100LL. If combustion were still taking place as you speculate then it would = ignite the incoming mixture during the intake cycle and cause a = backfire. So I think that is not it. I assume you've seen this but I found it interesting: http://www.wankel.org/74_Ignition/74-22%20Spark%20plug%20life%20.htm On Mon, Jul 6, 2009 at 7:17 PM, Steven Boese wrote: I never found the broken muffler part in the outlet of the muffler = where it might have caused increased back pressure even though it was = possible for it to end up in that location by standing the muffler on = its end. The symptoms after repairing the muffler were the same as = before the repair was made so at this point, I don't think the broken = part was a factor in the performance issue. Looking back at the data = log, the #2 rotor EGT dropped by about 250 degrees during the power = deficit. Back pressure would probably affect both rotors in a similar = fashion so that would also point to SAG as the culprit. =20 In response to your and Bobby's questions, at the onset of SAG, there = were a total of 15 hours on the plugs, 106 gal total of fuel burned, 53 = gal of that was 100LL. =20 Ed is most likely right that operating at the increased manifold = pressure available at low altitude made the SAG show up while it didn't = at lower manifold pressures that I normally see. =20 The relatively small amount of time and fuel that the plugs had seen = when SAG occurred may also be due to the low power levels and = correspondingly lower combustion temperatures permitting more rapid lead = deposition on the plugs. It looks like I should routinely change plugs = every 10 hours or so. I did have extra plugs along on the Texas trip = and it would have been easy to have installed them at the rotorfest. =20 The nature of SAG is puzzling. The symptoms of decreased EGT, = decreased power output, and increased heat transfer to the oil and = coolant are all consistent with descriptions of pre-ignition more than = that of spark plug misfire. In piston engines, pre-ignition can rapidly = lead to destruction, but the rotary engine may be more tolerant of it. = Maybe it isn't a matter of no ignition due to the spark plug not firing, = but a matter of the fire not going out between sparks. The lead in = 100LL increases the octane rating by slowing the combustion rate and = thereby decreasing the tendency for detonation. Maybe there is enough = gas phase lead in the vicinity of the spark plug with lead deposited on = it that the combustion rate is slowed enough to persist from one cycle = to the next while the normal combustion rate occurs in the rest of the = chamber. This could result in a process similar to pre-ignition. This = theory probably has as much probability of being right as the one I had = concerning the apex seals clicking. =20 Maybe I can accumulate a pile of SAGGING spark plugs as big as Ed's. = That would be verifiable at least. =20 =20 Steve Boese =20 =20 =20 =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Todd Bartrim Sent: Monday, July 06, 2009 6:23 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Muffler =20 Hi Steve; So you now assume that your power loss is directly attributable to = SAG and not to the partially blocked muffler? Is this correct? I'm curious as I also use a homemade muffler (SpinTech copy) and = have wondered what the result would be if any of the internal came = loose. I wonder if your increased backpressure contributed to the onset = of SAG? And do you only burn 100LL, occasionally, or never? =20 Todd C-FSTB RV9 Turbo13B=20 =20 =20 =20 __________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_00DF_01C9FFA4.7C074360 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Ed,
Would arsenic have any effect on lead, = I know it=20 dissolves some soft metals.
George ( down under)
 

Hi=20 Jeff,

 

Oh, I = don=92t throw=20 them out =96 I have a bushel basket of used plugs.  But, you are = right they=20 are around $5.00 down here when purchased in=20 bulk/box.

 

The 3 = electrode=20 ground shields the ceramic cone from the typical abrasive blasting = pretty=20 well. Make it a pain to clean the stock plugs, but they certainly do = not have=20 any noticeable wear after 25 hours so I save them. =20

 

I tried = several=20 methods =96 but despite what the gun shops advertise there is no = solvent for=20 lead short of foaming nitric acid (or something equally=20 hazardous).

 

I believe = that if=20 someone had a powerful ultrasonic cleaning machine that placing them = in a=20 solution of alcohol or something similar and using ultra sound to = blast the=20 lead crystals off the ceramic might do the job.  But, that is one = device=20 I do not have.

 

But, you = never know=20 when one may appear on ebay for $5.00 = {:>)

 

Ed

 

Ed=20 Anderson

Rv-6A = N494BW Rotary=20 Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm


From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Jeff Whaley
Sent:
Tuesday, July 07, 2009 = 12:44=20 PM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: SAG = was:=20 [FlyRotary] Re: Muffler

 

Hey = Ed, now=20 might be the time you cleaned a few SAG plugs and tested=20 them?

It = seems hard to=20 believe that plugs need be thrown out after 25=20 hours.

BTW, = up here in=20 Ottawa, I had to pay $17 each ($68 = per set) for=20 stock Mazda plugs, on a trip south I picked up some in Ogdensburg NY around $5=20 each.

Jeff

 

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Ed Anderson
Sent:
Tuesday, July 07, 2009 = 7:10=20 AM
To: = Rotary motors in aircraft
Subject: [FlyRotary] SAG was: = [FlyRotary]=20 Re: Muffler

 

There are = undoubtedly=20 numerous possibilities as to what is happening/causing SAG.  = However, two=20 things are very clear:

 

  1. 100 LL does definitely = reduce=20 the time spark plugs can be used before SAG occurs.  The = nominal time=20 period that I have found in my engine is 24-30 hours.  You can = take the=20 plug out and examine the ceramic  cone and see the glint of = what I=20 believe (but have not done a chemical analysis) of lead = crystals. =20 Folks using MOGAS (such as Tracy) have reported going over = 150 hours=20 without SAG.  So I do believe there is a connection between = 100LL and=20 the short interval of use before SAG. =

 

I even=20 attempted to use TCP which is used in some aircraft engines and is = reportedly=20 suppose to reduce lead deposits.  It simply make the problem = worst, but=20 upon further research I discovered that for this chemical to work the = cylinder=20 head temperature has to be much higher than what our water cooled = sparkplugs=20 typically see.  In my case, the chemical caused further deposits = (of some=20 sort)  on the sparkplug and I barely got 5 hours out of the set I = used.  This may in part explain why our sparkplugs seem to foul = more with=20 100LL than aircraft sparkplugs =96 they don=92t get hot = enough?  =20

 

  1. If you encounter SAG, = then=20 replacing the sparkplugs immediately eliminates the SAG problem (for = a=20 period of time). 

 

So both of = those=20 factors lead me to believe it is fouling of spark plugs rather than=20 pre-ignition.  If pre-ignition then my dozens of times of SAG = (like every=20 15 minutes on the 5 hour trip from Louisiana) would surely have = resulted in=20 damage to the engine. 

 

In any = case, whatever=20 the cause, since I have been replacing my sparkplugs regularly at = 25-30 hour=20 intervals I have encountered no SAG.  = YMMV

 

Ed

 

 

Ed=20 Anderson

Rv-6A = N494BW Rotary=20 Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm


From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of William Wilson
Sent:
Tuesday, July 07, 2009 = 12:09=20 AM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re:=20 Muffler

 

While the rotary design is a = little more=20 resistant to the onset of preignition, once it happens, the rotary is = damaged=20 just as easily as a piston engine or even more so.  Drag racers = suffering=20 preignition have dismantled their motors and found rotors dented in = from=20 excess chamber pressure.  It is possible that you have been = having mild=20 preignition not enough to damage the engine, I suppose.  Do you = suppose=20 you have been running really excessively rich?  That would also=20 contribute to plug fouling, low power and low EGT.  If you have = fuel=20 injection, a fuel map problem showing up only at high manifold = pressures=20 (higher than you normally attain in your usual operating regime) = maybe? =20 You should get WAY more than 10 hours on spark plugs even running=20 100LL.

If combustion were still taking place as you speculate = then it=20 would ignite the incoming mixture during the intake cycle and cause a=20 backfire.  So I think that is not it.

I assume you've seen = this=20 but I found it interesting:
http://www.wankel.org/74_Ignition/74-22%20Spark%20plug%20life%20.htm=

On Mon, Jul 6, 2009 at 7:17 PM, Steven Boese = <sboese@uwyo.edu>=20 wrote:

I never = found the=20 broken muffler part in the outlet of the muffler where it might have = caused=20 increased back pressure even though it was possible for it to end up = in that=20 location by standing the muffler on its end.  The symptoms after=20 repairing the muffler were the same as before the repair was made so = at this=20 point, I don=92t think the broken part was a factor in the performance = issue.  Looking back at the data log, the #2 rotor EGT dropped by = about=20 250 degrees during the power deficit.  Back pressure would = probably=20 affect both rotors in a similar fashion so that would also point to = SAG as the=20 culprit.

 

In response = to your=20 and Bobby=92s questions, at the onset of SAG, there were a total of 15 = hours on=20 the plugs, 106 gal total of fuel burned, 53 gal of that was=20 100LL.

 

Ed is most = likely=20 right that operating at the increased manifold pressure available at = low=20 altitude made the SAG show up while it didn=92t at lower manifold = pressures that=20 I normally see.

 

The = relatively small=20 amount of time and fuel that the plugs had seen when SAG occurred may = also be=20 due to the low power levels and correspondingly lower combustion = temperatures=20 permitting more rapid lead deposition on the plugs.  It looks = like I=20 should routinely change plugs every 10 hours or so.  I did have = extra=20 plugs along on the Texas trip and it would have been = easy to=20 have installed them at the rotorfest.

 

The nature = of SAG is=20 puzzling.  The symptoms of decreased EGT, decreased power output, = and=20 increased heat transfer to the oil and coolant are all consistent with = descriptions of pre-ignition more than that of spark plug = misfire.  In=20 piston engines, pre-ignition can rapidly lead to destruction, but the = rotary=20 engine may be more tolerant of it.  Maybe it isn=92t a matter of = no=20 ignition due to the spark plug not firing, but a matter of the fire = not going=20 out between sparks.  The lead in 100LL increases the octane = rating by=20 slowing the combustion rate and thereby decreasing the tendency for=20 detonation.  Maybe there is enough gas phase lead in the vicinity = of the=20 spark plug with lead deposited on it that the combustion rate is = slowed enough=20 to persist from one cycle to the next while the normal combustion rate = occurs=20 in the rest of the chamber. This could result in a process similar to=20 pre-ignition.  This theory probably has as much probability of = being=20 right as the one I had concerning the apex seals=20 clicking.

 

Maybe I can = accumulate a pile of SAGGING spark plugs as big as Ed=92s.  That = would be=20 verifiable at least.  =    

 

Steve Boese =  

 

 =20  

 

-----Original=20 Message-----
From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Todd = Bartrim
Sent: Monday, July 06, 2009 = 6:23=20 PM
To: = Rotary motors in=20 aircraft

Subject:=20 [FlyRotary] Re: Muffler

 

Hi=20 Steve;
    So you now assume that your power loss is = directly attributable to SAG and not to the partially blocked muffler? = Is this=20 correct?
     I'm curious as I also use a = homemade=20 muffler (SpinTech copy) and have wondered what the result would be if = any of=20 the internal came loose. I wonder if your increased backpressure = contributed=20 to the onset of SAG? And do you only burn 100LL, occasionally, or=20 never?

 

Todd
C-FSTB
RV9 Turbo13B=20

 

 



__________ Information from ESET = NOD32=20 Antivirus, version of virus signature database 3267 (20080714)=20 __________

The message was checked by ESET NOD32 = Antivirus.

http://www.eset.com

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