X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from willowsprings.uwyo.edu ([129.72.10.31] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTPS id 4488005 for flyrotary@lancaironline.net; Thu, 30 Sep 2010 16:22:17 -0400 Received-SPF: none receiver=logan.com; client-ip=129.72.10.31; envelope-from=SBoese@uwyo.edu Received: from ponyexpress-ht2.uwyo.edu (ponyexpress-ht2.uwyo.edu [10.84.60.209]) by willowsprings.uwyo.edu (8.14.4/8.14.4) with ESMTP id o8UKL8wV024662 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL) for ; Thu, 30 Sep 2010 14:21:39 -0600 (MDT) (envelope-from SBoese@uwyo.edu) Received: from ponyexpress-mb5.uwyo.edu ([fe80::9813:248c:2d68:a28b]) by ponyexpress-ht2 ([10.84.60.209]) with mapi; Thu, 30 Sep 2010 14:21:26 -0600 From: "Steven W. Boese" To: Rotary motors in aircraft Date: Thu, 30 Sep 2010 14:21:26 -0600 Subject: RE: [FlyRotary] Re: SAG from Paducah Thread-Topic: [FlyRotary] Re: SAG from Paducah Thread-Index: ActgvqrfPJm5WCKaSCC4/OrG7+o5PgAGZDaW 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_E1AA3B1AF41D8049B1E3FBD5E225626004E2453FE3ponyexpressmb_" MIME-Version: 1.0 --_000_E1AA3B1AF41D8049B1E3FBD5E225626004E2453FE3ponyexpressmb_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn, I believe we all appreciate your input and benefit from your experience and= insights. I would like to respond (in italics) to points you made below = to make sure I understand what you are saying. I for one am looking forwar= d to "more later". Steve Boese Let us review............... We take an engine from a car that usually operates below 2,200 RPM, and at = partial throttle for 99.5% of its life, and put it in airplane and run it a= t 6,000 RPM and wide open throttle for hours on end, and even a cold street= plug is boiling cement and rounding electrodes? Now who could have guessed= that would happen. Many times the statement has been made that we are not pushing the rotary= engine nearly as hard in the aircraft application as it is in the racing s= ituation and racing modifications are generally not necessary for the aircr= aft. Is the spark plug an exception to this? If the spark plug heat range= was inappropriate when new, it is puzzling that the problem with it takes = 30 or more hours to show up when using 100LL fuel and hundreds of hours for= the problem to develop when using auto fuel. The overheated plug boils the cement near the tip of the plug, thermally d= isconnecting the electrode from the ceramic, and allowing the electrode tem= perature to run away. We do not observe that type of damage to the spark plugs. The informati= on I have seen indicates that it is the insulator where it pinches out at t= he tip that becomes too hot. The electrode itself is much more closely the= rmally coupled to the cooling system. This could lead to preignition (an ignition event that occurs before the pl= anned ignition). Unless the mixture is well rich of ideal or well lean of i= deal, the pre-ignition would lead quickly to detonation followed by the ape= x seals getting stuck in the muffler. Which is precisely why it would be nice to know what is actually happening= . How close to the edge of disaster are we really operating? The high performance Mazda street plugs (turbo plugs) have shielding on the= shell ends similar in appearance to some aircraft plugs. They are not airc= raft plugs. They will not survive hours at full load wide open throttle. Th= e heat range is cooler than most street plugs it is true, but nothing like = a racing plug. Racing Beat must define a "racing plug" differently. Real racing plugs do not have that shielding. They have a welded ground ele= ctrode or a fine wire ground electrode stuck through the side of the shell.= They have porcelain filling the shell all the way to the end and may have = a fine wire center electrode. They are as cold a heat range as is possible = to produce. They are orders of magnitude colder than the coldest street plu= g. More later. Lynn E. Hanover --_000_E1AA3B1AF41D8049B1E3FBD5E225626004E2453FE3ponyexpressmb_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Lynn,
 
I believe we all appreciate your input and benefit from you= r experience and insights.  I would like to respond  (in italics) to points you made below to make sure I understand= what you are saying.  I for one am looking forward to "more= later".
 
Steve Boese
 
Let us review...............
 
We take an engine from a car that usually operates below 2,200 RPM, an= d at partial throttle for 99.5% of its life, and put it in airplane an= d run it at 6,000 RPM and wide open throttle for hours on end, and even a c= old street plug is boiling cement and rounding electrodes? Now who could have guessed that would happen.
  Many times the statement has been made that we are not push= ing the rotary engine nearly as hard in the aircraft application as it= is in the racing situation and racing modifications are generally&nbs= p;not necessary for the aircraft.  Is the spark plug an exception to this?  If the spark plug heat range was inapprop= riate when new, it is puzzling that the problem with it takes 30 or more ho= urs to show up when using 100LL fuel and hundreds of hours for the problem = to develop when using auto fuel.    
 
The overheated plug boils the cement  near the tip of the plug, t= hermally disconnecting the electrode from the ceramic, and allowing the ele= ctrode temperature to run away.
   We do not observe that type of damage to the spa= rk plugs.  The information I have seen indicates that it is the insula= tor where it pinches out at the tip that becomes too hot.  The electro= de itself is much more closely thermally coupled to the cooling system. 
 
This could lead to preignition (an ignition event that occurs before t= he planned ignition). Unless the mixture is well rich of ideal or well lean= of ideal, the pre-ignition would lead quickly to detonation followed by th= e apex seals getting stuck in the muffler.
 Which is precisely why it would be nice to know what is actu= ally happening.  How close to the edge of disaster are we really opera= ting?
 
The high performance Mazda street plugs (turbo plugs) have shielding o= n the shell ends similar in appearance to some aircraft plugs. They are not= aircraft plugs. They will not survive hours at full load wide open throttl= e. The heat range is cooler than most street plugs it is true, but nothing like a racing plug.
  Racing Beat must define a "racing plug" diff= erently. 
 
Real racing plugs do not have that shielding. They have a welded groun= d electrode or a fine wire ground electrode stuck through the side of = the shell. They have porcelain filling the shell all the way to the end and= may have a fine wire center electrode. They are as cold a heat range as is possible to produce. They are orders o= f magnitude colder than the coldest street plug.  
 
More later.
 
Lynn E. Hanover
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