X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from st11p02mm-asmtp003.mac.com ([17.172.220.238] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTP id 6398992 for flyrotary@lancaironline.net; Wed, 31 Jul 2013 23:56:57 -0400 Received-SPF: pass receiver=logan.com; client-ip=17.172.220.238; envelope-from=markmcclure@me.com Received: from [192.168.0.4] (ip98-183-228-236.hr.hr.cox.net [98.183.228.236]) by st11p02mm-asmtp003.mac.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Jan 3 2012)) with ESMTPSA id <0MQU00D7C2XFH960@st11p02mm-asmtp003.mac.com> for flyrotary@lancaironline.net; Thu, 01 Aug 2013 03:56:04 +0000 (GMT) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.10.8794,1.0.431,0.0.0000 definitions=2013-07-31_09:2013-07-31,2013-07-31,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 suspectscore=2 phishscore=0 bulkscore=1 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1305010000 definitions=main-1307310277 References: MIME-version: 1.0 (1.0) In-reply-to: Content-type: multipart/alternative; boundary=Apple-Mail-984FD7C6-7923-4699-BB52-2DA4C8FD8FA3 Content-transfer-encoding: 7bit Message-id: <657F2E58-1D7F-4D38-8B6C-9BA2477CFEDE@me.com> Cc: Rotary motors in aircraft X-Mailer: iPad Mail (10A523) From: Mark McClure Subject: Re: [FlyRotary] Re: Fwd: [FlyRotary] Re: : Misfire Date: Wed, 31 Jul 2013 23:56:04 -0400 To: Rotary motors in aircraft --Apple-Mail-984FD7C6-7923-4699-BB52-2DA4C8FD8FA3 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Lynn, Just want you to know, was having a rough day out at the hangar, your signat= ure turned it all around.=20 So to better understand, the trailing plugs main purpose is to effect a smoo= ther and more complete burn of the mixture. The plan to open the hole would b= e to try and gain 75% power on either leading or trailing plug... Based on t= railing plug being clean up, would you not instead have to put a second hole= next to both leading and trailing plug creating 4 plugs per rotor? Mark On Jul 31, 2013, at 11:29 PM, Lehanover@aol.com wrote: > In a message dated 7/31/2013 8:04:11 P.M. Eastern Daylight Time, shipchief= @aol.com writes: > So my engine may have detonated simply because the engine builder opened u= p the upper (trailing) spark plug holes to improve the redundant dual igniti= on idea of an aircraft engine? > As rpm and boost increased the compression of the intake charge? The fire c= ould jump the apex seal at the big hole and light the leading edge of the in= take charge just as the intake ports are closing?! >=20 > Sent from my iPhone > Well, Yes if that hole were increased in diameter.................... > =20 > That hole is small in order to prevent a loss of compression (Primarily) a= nd to reduce the chance of a preignition event in the following charge. Our f= riends down under have run some engines with the little hole > made a bit wider in order to make the trailing plug more useful, but with n= o change in height in order to avoid > the preignition problem. The change in width would probably have little af= fect on performance, even at low speed. Remember, very low cylinder pressure= at or near idle. The trailing plug is set back into a chamber of some volum= e. The trailing plug is fired some time after the leading plug. Some fuel ai= r mixture is forced into this chamber before the trailing plug fires, and th= en a bit of burning mixture is shot out of the trailing hole in order to bur= n more of the hard to light idle mixture. This effect is limited to a very s= mall RPM range and works over a small range of timing splits. Or, the length= of time allowed between the leading and trailing firing events. This idea h= elps in the burning of excess fuel at idle and near idle RPM. This is so the= cars could be sold in the Peoples Republic of California. The HC output you= see. > =20 > The trailing plug is of little value at full song in the airplane RPM rang= e. There could be some danger moving the throttles too quickly from a lower R= PM, where there is more time (Lower RPM) for a flame front to move across th= e enlarged hole. The M in RPM is the time problem. > =20 > A preignition event at higher power settings would be profound and probabl= y unforgettable. (Although one of my drivers would have missed it). A big en= gine shake and maybe a sheared dowel and, or, a broken dowel hole in the iro= n. Maybe an oil fire and big dripping mess. > =20 > In a NA engine probably no problems with slow throttle movements. In a boo= sted engine a much bigger problem, if boost is available at lower RPM. Even m= ore important to move slower on throttle in those engines. > =20 > If you have lost an engine with suspect trailing plug holes, I would not u= se those housings in anything. > =20 > Racing Beat says to use no split timing in boosted engines. Also, once boo= st is up not more than 12 degrees of advance is used. They use 10 on the dyn= o and race on 12 degrees. No split is used, as the engine sees this as a det= onation event. As boost goes up, the effective compression ratio goes up. Th= e idea is that you are making the displacement go up while the head space st= ays the same volume. =20 > So where a low compression engines may need, for example, 24 to 27 degrees= of advance to get maximum cylinder pressure at 50 degrees ATDC. The boosted= engine (high compression) may need only 10 to 12 degrees to get maximum cyl= inder pressure at 50 degrees ATDC. The flame front speed is much higher so l= ess time (ignition advance) is needed. > =20 > Lynn E. Hanover > Making boat anchors > out of rotary engines > since 1980 > =20 > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List= .html --Apple-Mail-984FD7C6-7923-4699-BB52-2DA4C8FD8FA3 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit
Lynn,

Just want you to know, was having a rough day out at the hangar, your signature turned it all around. 

So to better understand, the trailing plugs main purpose is to effect a smoother and more complete burn of the mixture. The plan to open the hole would be to try and gain 75% power on either leading or trailing plug... Based on trailing plug being clean up, would you not instead have to put a second hole next to both leading and trailing plug creating 4 plugs per rotor?

Mark

On Jul 31, 2013, at 11:29 PM, Lehanover@aol.com wrote:

In a message dated 7/31/2013 8:04:11 P.M. Eastern Daylight Time, shipchief@aol.com writes:
So my engine may have detonated simply because the engine builder opened up the upper (trailing) spark plug holes to improve the redundant dual ignition idea of an aircraft engine?
As rpm and boost increased the compression of the intake charge? The fire could jump the apex seal at the big hole and light the leading edge of the intake charge just as the intake ports are closing?!

Sent from my iPhone
Well, Yes if that hole were increased in diameter....................
 
That hole is small in order to prevent a loss of compression (Primarily) and to reduce the chance of a preignition event in the following charge. Our friends down under have run some engines with the little hole
made a bit wider in order to make the trailing plug more useful, but with no change in height in order to avoid
the preignition problem. The change in width would probably have little affect on performance, even at low speed. Remember, very low cylinder pressure at or near idle. The trailing plug is set back into a chamber of some volume. The trailing plug is fired some time after the leading plug. Some fuel air mixture is forced into this chamber before the trailing plug fires, and then a bit of burning mixture is shot out of the trailing hole in order to burn more of the hard to light idle mixture. This effect is limited to a very small RPM range and works over a small range of timing splits. Or, the length of time allowed between the leading and trailing firing events. This idea helps in the burning of excess fuel at idle and near idle RPM. This is so the cars could be sold in the Peoples Republic of California. The HC output you see.
 
The trailing plug is of little value at full song in the airplane RPM range. There could be some danger moving the throttles too quickly from a lower RPM, where there is more time (Lower RPM) for a flame front to move across the enlarged hole. The M in RPM is the time problem.
 
A preignition event at higher power settings would be profound and probably unforgettable. (Although one of my drivers would have missed it). A big engine shake and maybe a sheared dowel and, or, a broken dowel hole in the iron. Maybe an oil fire and big dripping mess.
 
In a NA engine probably no problems with slow throttle movements. In a boosted engine a much bigger problem, if boost is available at lower RPM. Even more important to move slower on throttle in those engines.
 
If you have lost an engine with suspect trailing plug holes, I would not use those housings in anything.
 
Racing Beat says to use no split timing in boosted engines. Also, once boost is up not more than 12 degrees of advance is used. They use 10 on the dyno and race on 12 degrees. No split is used, as the engine sees this as a detonation event. As boost goes up, the effective compression ratio goes up. The idea is that you are making the displacement go up while the head space stays the same volume.  
So where a low compression engines may need, for example, 24 to 27 degrees of advance to get maximum cylinder pressure at 50 degrees ATDC. The boosted engine (high compression) may need only 10 to 12 degrees to get maximum cylinder pressure at 50 degrees ATDC.  The flame front speed is much higher so less time (ignition advance) is needed.
 
Lynn E. Hanover
Making boat anchors
out of rotary engines
since 1980
 
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