X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 31 May 2008 09:22:13 -0400 Message-ID: X-Original-Return-Path: Received: from sfa.gami.com ([68.89.254.162] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTP id 2946459 for lml@lancaironline.net; Fri, 30 May 2008 20:09:21 -0400 Received-SPF: none receiver=logan.com; client-ip=68.89.254.162; envelope-from=gwbraly@gami.com Received: from localhost (localhost.localdomain [127.0.0.1]) by sfa.gami.com (Postfix) with ESMTP id 78FF029C076 for ; Fri, 30 May 2008 19:08:39 -0500 (CDT) Received: from gamimail1.Gami.local (unknown [10.10.10.33]) by sfa.gami.com (Postfix) with ESMTP id 19D1029C073 for ; Fri, 30 May 2008 19:08:39 -0500 (CDT) Received: from gamimail1.Gami.local ([10.10.10.33]) by gamimail1.Gami.local ([10.10.10.33]) with mapi; Fri, 30 May 2008 19:08:36 -0500 From: George Braly X-Original-To: Lancair Mailing List X-Original-Date: Fri, 30 May 2008 19:08:34 -0500 Subject: RE: [LML] Re: Electronic ignition spark plugs Thread-Topic: [LML] Re: Electronic ignition spark plugs Thread-Index: AcjCqcGXHP/KnsoKRiW/6cmqMwPbqgAAH2Zg X-Original-Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_C273A1B35F3C6748B52EE0CC2FCEE96C6DE070EC11gamimail1Gami_" MIME-Version: 1.0 X-Virus-Scanned: by amavisd-new-2.3.2 (20050629) (Debian) at gami.com --_000_C273A1B35F3C6748B52EE0CC2FCEE96C6DE070EC11gamimail1Gami_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Chuck, I'm sorry if my posting was disappointing. But I tried to make sure it was factual and informative. It may not be he= lpful - - for those that want to go ahead and hope that the automtoive plu= gs will work in their application. I am NOT asserting that the automotive splugs are, in fact, unsatisfactory. What I AM asserting is that unless someone has meaesured the actual temper= ature of the ceramic in the automotive plug inserted into the aircraft air = cooled cylinder then the people using the automotive spark plug are relying= on "hope as a method" to establish safety for the configuration of their e= ngines. Given that there are apparently reliable reports of pre-ignition with the = use of automotive spark plugs in common aircraft engines - - then there is = hard evidence that the heat range of the plugs is marginal at best and unsu= itable in at least some portions of the normal operating envelope. >> What is it about auto plugs that are inadequate? Peak temp tolerance? = Temp rate of change? Cylinder compression? 100LL gas? Where do they fal= l short, ...<< I don't know where they fall short in any or all of the areas about which y= ou inquire. But none of those are the one about which I am most concerned. The operating temperature of the spark plug ceramic under hot day high powe= r conditions across the full range of allowable combustion A/F ratios is th= e first area of concern. If it doesn't qualify there - - then nothing else= matters. And so far as I can tell - - nobody in the experimental aircraft world know= s the answer to that question. They may be just fine and run along at a c= ool 1200d F. Or not. But everybody keeps hoping "yes" but nobody knows and= nobody has the data. I assume that you agree that hope should not be a me= thod of assurance for safety critical items in aircraft. The fact that some people have run automotive plugs successfully in some en= gines - - is a lot like saying that some people have successfully used car= gas in their aircraft engine. Unless you know that they have used that gasoline under the worst case cond= itions that YOU will ever encounter with your engine and that your engine i= s "less critical or the same" as the engine that someone else used - - and = that when you buy your automotive gas from your local dealer that it will b= e the same or equivelent gas bought from the earlier supplier for the earli= er test - - - then you really are just following the "hope as a method" co= ncept for assuring that your use of similar car gasoline would work in you= r particular application. I can go out and run a 350 Hp Navajo Chieftan turbocharged engine all day a= t 210 Hp and do it on premium car gas. But if I try to run it at 230 Hp on a hot day with hot cylinders in a singl= e engine climb - - it is going to detonate. Or if I try to run it at 270 Hp on any day, it is going to detonate. But if I just told people that " I have run a TIO-540J2Bd engine on car gas= " - - - then it is likely that someone else will decide to follow the "hop= e as a method" concept and try the same thing - - with disasterous results. I know what the actual heat range for the aircraft plugs is in the high per= formance aircraft engine and the temperature margins that are present. But if I were to insert an automotive plug into a bushing screwed into the = cylinder head of my air cooled aircraft engine I would have to merely "= hope" that it was going to work based on a mixed set of anecdotal testimon= ials about their successful and unsuccessful use in aircraft engines report= ed by others. That is all I am saying. Hope is not really a method. Regards, George ________________________________ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Chuc= k Jensen Sent: Friday, May 30, 2008 6:06 PM To: lml@lancaironline.net Subject: [LML] Re: Electronic ignition spark plugs George, Your postings are quite surprising, and a bit disappointing. You point out= that auto plugs are different that aviation plugs. You point out that you= know the temperature of the aviation plugs during operations. You point o= ut that auto plugs enjoys a heat sunk environment. You point out that the = aviation plug was designed for the aviation environment. All of these are true, but unfortunately, you leave us to 'conclude' that t= hat somehow means that the auto plug are unsatisfactory in the aviation env= ironment. I don't like having to bridge such gaps in data. What is it ab= out auto plugs that are inadequate? Peak temp tolerance? Temp rate of cha= nge? Cylinder compression? 100LL gas? Where do they fall short, other th= an they are 'different' from aviation plugs? Personally, I run aviation plugs on both my mag and EI, but many have run a= uto plugs without problems. Why, or how, were they successful when there a= re so many implied deficiencies with auto plugs? Thanks, Chuck Jensen -----Original Message----- From: Lancair Mailing List [mailto:lml@lancaironline.net]On Behalf Of Georg= e Braly Sent: Friday, May 30, 2008 9:45 AM To: lml@lancaironline.net Subject: [LML] Re: Electronic ignition spark plugs Colyn, Other than curiosity - - it is not, frankly, important that I know what t= he number is supposed to be - - What is important is that nobody has a clue as to what the number is for th= e automotive spark plug mounted in the aircraft application. Keep in mind that the automotive spark plug enjoyes being "heat sunk" into= a massive water cooled cylinder head that is held at constant temperature = from a thermostat. By contrast, the aircraft spark plug is desgined for the much more variable= environment of the air cooled cylinder head which can have temperatures mo= re than twice as high as the automotive cylinder head. There is a casual acceptance of a substantial level of "under-investigati= on" that is associated with some of these often routinely accepted recomm= endations to use components that have not undergone thoughtful testing at= the boundary conditions of realistic operating environments. Regards, George PS> The answer to your question is in some of the APS class materials. We= made a power point slide that detailed the aircraft spark plug ceramic tem= perature as a function of A/F ratio. ________________________________ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Coly= n Case at earthlink Sent: Wednesday, May 28, 2008 9:37 PM To: lml@lancaironline.net Subject: [LML] Re: Electronic ignition spark plugs George said I can tell you the answer to that question with respect to an aviation spar= k plug. okay, what's the answer? say, 50 dF LOP 32" TSIO-550 ....or whatever you ac= tually have. --_000_C273A1B35F3C6748B52EE0CC2FCEE96C6DE070EC11gamimail1Gami_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
 
 
Chuck,
 
I'm sorry if my posting was=20 disappointing.
 
But I tried to make sure it was factual and=20 informative.   It may not be helpful - -  for those that wan= t to=20 go ahead and hope that the automtoive plugs will work in their=20 application.
 
I am NOT asserting that the automotive splugs are,= in fact,=20 unsatisfactory. 
 
What I  AM asserting is that unless someone h= as=20 meaesured the actual temperature of the ceramic in the automotive plug inse= rted=20 into the aircraft air cooled cylinder then the people using the automotive = spark=20 plug are relying on "hope as a method" to establish safety= for=20 the configuration of their engines.
 
Given that there are apparently reliable reports o= f =20 pre-ignition with the use of automotive spark plugs in common aircraft engi= nes -=20 - then there is hard evidence that the heat range of the plugs is marginal = at=20 best and unsuitable in at least some portions of the normal operating=20 envelope.
 
>> What  is it about auto plugs that ar= e=20 inadequate?  Peak temp tolerance?  Temp rate of change?  Cyl= inder=20 compression?  100LL gas?  Where do they fall short,=20 ...<<
 
I don't know where they fall short in any or all o= f the=20 areas about which you inquire.  But none of those are the one about wh= ich I=20 am most concerned.
 
The operating temperature of the spark plug cerami= c under=20 hot day high power conditions across the full range of allowable combustion= A/F=20 ratios is the first area of concern.  If it doesn't qualify there - - = then=20 nothing else matters.
 
And so far as I can tell - - nobody in the experim= ental=20 aircraft world knows the answer to that question.   They may be j= ust=20 fine and run along at a cool 1200d F.  Or not. But everybody keeps hop= ing=20 "yes" but nobody knows and nobody has the data.  I assume that you agr= ee=20 that hope should not be a method of assurance for safety critical item= s in=20 aircraft.
 
 
The fact that some people have run automotive plug= s=20 successfully in some engines - -  is a lot like saying that some peopl= e=20 have successfully used car gas in their aircraft engine.
 
Unless you know that they have used that gasoline = under the=20 worst case conditions that YOU will ever encounter with your engine and tha= t=20 your engine is "less critical or the same" as the engine that someone else = used=20 - - and that when you buy your automotive gas from your local dealer that i= t=20 will be the same or equivelent gas bought from the earlier supplier fo= r the=20 earlier test - - -  then you really are just following the "hope as a= =20 method" concept for assuring that your use of similar car gasoline would&nb= sp;=20 work in your particular application.
 
I can go out and run a 350 Hp Navajo Chieftan= =20 turbocharged engine all day at 210 Hp and do it on premium car gas. &n= bsp;=20
 
But if I try to run it at 230 Hp on a hot day with= hot=20 cylinders in a single engine climb - - it is going to=20 detonate.
 
Or if I try to run it at 270 Hp on any day, it is = going to=20 detonate.
 
But if I just told people that " I have run a TIO-= 540J2Bd=20 engine on car gas" - - -  then it is likely that someone else will dec= ide=20 to follow the "hope as a method" concept and try the same thing - - with=20 disasterous results.
 
I know what the actual heat range for the aircraft= plugs is=20 in the high performance aircraft engine and the temperature margins that ar= e=20 present.
 
But if I were to insert an automotive plug into a = bushing=20 screwed into the  cylinder head  of my air cooled  aircraft= =20 engine I would have to merely  "hope"  that it was going to work = based=20 on a mixed set of anecdotal testimonials about their successful and unsucce= ssful=20 use in aircraft engines reported by others.
 
That is all I am saying.
 
Hope is not really a method.
 
Regards,  George
 
 
 
 
 
 
 
 
 
From: Lancair Mailing List=20 [mailto:lml@lancaironline.net] On Behalf Of Chuck Jensen
Sent:= =20 Friday, May 30, 2008 6:06 PM
To:=20 lml@lancaironline.net
Subject: [LML] Re: Electronic ignition spar= k=20 plugs

George,
 
Your=20 postings are quite surprising, and a bit disappointing.  You point out= that=20 auto plugs are different that aviation plugs.  You point out that you = know=20 the temperature of the aviation plugs during operations.  You point ou= t=20 that auto plugs enjoys a heat sunk environment.  You point out that th= e=20 aviation plug was designed for the aviation environment.
 
All of=20 these are true, but unfortunately, you leave us to 'conclude' that that som= ehow=20 means that the auto plug are unsatisfactory in the aviation=20 environment.  I don't like having to bridge such gaps in data.&nb= sp;=20 What  is it about auto plugs that are inadequate?  Peak temp=20 tolerance?  Temp rate of change?  Cylinder compression?  100= LL=20 gas?  Where do they fall short, other than they are 'different' from=20 aviation plugs?
 
Personally, I run aviation plugs on both my mag and EI, but many h= ave run=20 auto plugs without problems.  Why, or how, were they successful when t= here=20 are so many implied deficiencies with auto plugs?

Thanks, Chuck=20 Jensen

 

-----Original Message-----
From: Lancair Mailing List= =20 [mailto:lml@lancaironline.net]On Behalf Of George Braly
Sent= :=20 Friday, May 30, 2008 9:45 AM
To:=20 lml@lancaironline.net
Subject: [LML] Re: Electronic ignition sp= ark=20 plugs

Colyn,
 
Other than curiosity - -   it is not,= =20 frankly, important that I know what the number is supposed to be - -= =20
 
What is important is that nobody has a c= lue=20 as to what the number is for the automotive spark plug mounted i= n the=20 aircraft application.
 
Keep=20 in mind that the automotive spark plug enjoyes being "heat sunk"  in= to a=20 massive water cooled cylinder head that is held at constant temperature f= rom a=20 thermostat.
 
By=20 contrast, the aircraft spark plug is desgined for the much more variable= =20 environment of the air cooled cylinder head which can have temperatures m= ore=20 than twice as high as the automotive cylinder head.
 
There is a  casual acceptance of a substa= ntial=20 level of <= SPAN=20 class=3D872145823-29052008> "under-investigation"  that is associate= d with=20 some of these often routinely accepted  recommendations to use compo= nents=20 that have not undergone   thoughtful testing at the boundary=20 conditions of  realistic operating=20 environments.  
 
Regards,  George
 
PS>  The answer to your question is in= some=20 of the APS class materials.  We made a power point slide that detail= ed=20 the aircraft spark plug ceramic temperature as a function of  A/F=20 ratio.
 

From: Lancair Mailing List=20 [mailto:lml@lancaironline.net] On Behalf Of Colyn Case at=20 earthlink
Sent: Wednesday, May 28, 2008 9:37 PM
To:=20 lml@lancaironline.net
Subject: [LML] Re: Electronic ignition sp= ark=20 plugs

George said
I can tell you the answer to that question with= =20 respect to an aviation spark plug.
 
okay, what's the answer? say, 50 dF LOP 32" TS= IO-550=20 ....or whatever you actually have.
 
 
--_000_C273A1B35F3C6748B52EE0CC2FCEE96C6DE070EC11gamimail1Gami_--