X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-lpp01m010-f52.google.com ([209.85.215.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTPS id 5438154 for flyrotary@lancaironline.net; Mon, 12 Mar 2012 08:20:16 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.52; envelope-from=rwstracy@gmail.com Received: by lahi5 with SMTP id i5so3284587lah.25 for ; Mon, 12 Mar 2012 05:19:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=INCnhnkim9eXI5/McxCcdYsiVogZWQ67oomJMTZ6+cw=; b=GaIIK2tOQ7cg21Zehyjj5mmyO0hK4uBsCVt8UEmf0YYstv2F2r1n0ysYBepRcO5Hfx DIeGfrOaT7IAch2v84yGw34B/nqcZW1GWW+XFWdRRi9ndJtxlkff+J39q4HxiMotJoYJ 9XCDMiyZo+pHE4s1mE3Go2P6M1Vlzzf6Nzj7n6P4uQgHXII/pyulEGdsE4VoGfy4pEhN WHSuhc0Ym+gmyh/Gb0EeP2Vzpfs0fncByQUGgvg5Tvn4b2yclOxb5GyDbM3hlsN6fSKh HlUt41J65J58SYg+xccnHe/7XpiKr/3DcyOOWSAk5dSu02CmgH98oAj6RxStA5G0nBcQ NzLw== MIME-Version: 1.0 Received: by 10.152.145.131 with SMTP id su3mr4472803lab.46.1331554778790; Mon, 12 Mar 2012 05:19:38 -0700 (PDT) Received: by 10.112.94.179 with HTTP; Mon, 12 Mar 2012 05:19:38 -0700 (PDT) In-Reply-To: References: Date: Mon, 12 Mar 2012 08:19:38 -0400 Message-ID: Subject: Re: [FlyRotary] Re: Failure of an LS-1 D-580 type ignition coil From: Tracy To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=e89a8f234ab596b93104bb0ac1b1 --e89a8f234ab596b93104bb0ac1b1 Content-Type: text/plain; charset=ISO-8859-1 This is a different thing entirely. My guess is that your mixture is changing at lower MP and raising the EGT. Assuming the ignition timing is OK, this is probably what you want. Higher EGT due to leaner mixture at low power wont hurt anything within limits. I don't know the limits of this engine of course. What does your mixture monitor tell you under these conditions compared to high throttle? Tracy On Sun, Mar 11, 2012 at 10:51 PM, Rob wrote: > ** > Is this the same thing that happens when manifold pressure is reduced but > RPM is increased, like when I reduce throttle to go to a lower altitude or > for landing? When I do this my EGT starts to climb to 1600 or even 1700 > degrees. This in on my Ford V6 with Tracy's EC2 and EM2. It dosen't make > cents in this case either so it must be the same phenomenon. Do I need to > worry about this climbing EGT or not? > Thanks for any insights? > > Robert Bollinger > > ----- Original Message ----- > *From:* Tracy > *To:* Rotary motors in aircraft > *Sent:* Saturday, March 10, 2012 8:22 AM > *Subject:* [FlyRotary] Re: Failure of an LS-1 D-580 type ignition coil > > The other guys pretty much nailed it. Less burning in the chamber and > more burning in the exhaust header. > > Tracy > > Sent from my iPad > > On Mar 9, 2012, at 11:53 PM, Dave wrote: > > On 3/9/2012 10:22 PM, DLOMHEIM@aol.com wrote: > > Tracy wrote: >As usual, the in-flight symptom was a rise in EGT on the > affected rotor. > > Can someone describe the science behind a "rise in EGT" when we lose a > single coil. I would have expected a drop in EGT due to less thorough > burning of the mixture and therefore excess un-burnt fuel which I thought > would provide cooler temps of the exhaust stream as it passes the EGT probe. > > Must be missing something very basic here... > > Thanks for any clarity! :) > > Doug Lomheim > RV-9A / 13B FWF > > > The rotor combustion space is long and narrow at TDC. If you ignite the > fuel air charge in a rotary at tdc from only one end, the flame front > progresses slowly from one end of the "combustion chamber" to the other. > Two plugs (and coils) for each rotor are present in order to facilitate > complete burning of the fuel-air charge from opposite ends, and to extract > as much power from the charge as possible before the "power stroke" portion > of rotor rotation uncovers an exhaust port and begins the "exhaust stroke" > > So.. in an abnormal condition characterized by a single coil failure (out > of 4 coils).. the affected plug is dead... and the affected rotor has > incomplete and SLOWER burning of the charge than normal. This delayed > burning persists after the exhaust port is uncovered. So instead of exhaust > gases (which have already lost heat to the block) passing by the EGT probe, > you have actual flame front (from the still burning fuel air charge) > passing the probe and combustion continues in the tailpipe. That explains > why EGT on the affected rotor would rise in a rotary with dual plugs/coils > per rotor. A single dead plug from fouling or other causes could also > provide the same result. > > Make Sense? > Dave (a lingering former rotorhead) > > --e89a8f234ab596b93104bb0ac1b1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable This is a different thing entirely.=A0=A0 My guess is that your mixture is = changing at lower MP and raising the EGT.=A0=A0 Assuming the ignition timin= g is OK, this is probably what you want.=A0 Higher EGT due to leaner mixtur= e at low power wont hurt anything within limits.=A0=A0 I don't know the= limits of this engine of course.=A0=A0 What does your mixture monitor tell= you under these conditions compared to high throttle?

Tracy

On Sun, Mar 11, 2012 at 10:51 P= M, Rob <rob@mum.edu= > wrote:
Is this the same thing that happens when manifold= =20 pressure is reduced but RPM is increased, like when I reduce throttle to go= to a=20 lower altitude or for landing? When I do this my EGT starts to climb to 160= 0 or=20 even 1700 degrees. This in on my Ford V6 with Tracy's EC2 and EM2.=A0= =A0=20 It dosen't make cents in this case either so it must be the same phenom= enon. Do=20 I need to worry about this climbing EGT or not?
Thanks for any insights?
=A0
Robert Bollinger
----- Original Message -----
From:=20 Tracy
Sent: Saturday, March 10, 2012 8:22= =20 AM
Subject: [FlyRotary] Re: Failure of= an=20 LS-1 D-580 type ignition coil

The other guys pretty much nailed it. =A0 Less burning in the chambe= r=20 and more burning in the exhaust header.

Tracy

Sent from my iPad

On Mar 9, 2012, at 11:53 PM, Dave <david.staten@gmail.com>=20 wrote:

On 3/9/2012 10:22 PM, DLOMH= EIM@aol.com wrote:=20
Tracy wrote:=A0 >As usual, the in-flight symptom was a rise i= n=20 EGT on the affected rotor.
=A0
Can someone describe the science behind a "rise in EGT"= ; when we lose=20 a single coil.=A0 I would have expected a drop in EGT due to less=20 thorough burning of the mixture and therefore=A0excess un-burnt fuel= =20 which I thought would provide=A0cooler temps of the exhaust stream=20 as=A0it passes the=A0EGT probe.
=A0
Must be missing something very basic here...
=A0
Thanks for any clarity!=A0 :)
=A0
Doug Lomheim
RV-9A / 13B FWF

The rotor combustio= n space=20 is long and narrow at TDC. If you ignite the fuel air charge in a rotar= y at=20 tdc from only one end, the flame front progresses slowly from one end o= f the=20 "combustion chamber" to the other. Two plugs (and coils) for = each rotor are=20 present in order to facilitate complete burning of the fuel-air charge = from=20 opposite ends, and to extract as much power from the charge as possible= =20 before the "power stroke" portion of rotor rotation uncovers = an exhaust port=20 and begins the "exhaust stroke"

So.. in an abnormal co= ndition=20 characterized by a single coil failure (out of 4 coils).. the affected = plug=20 is dead... and the affected rotor has incomplete and SLOWER burning of = the=20 charge than normal. This delayed burning persists after the exhaust por= t is=20 uncovered. So instead of exhaust gases (which have already lost heat to= the=20 block) passing by the EGT probe, you have actual flame front (from the = still=20 burning fuel air charge) passing the probe and combustion continues in = the=20 tailpipe. That explains why EGT on the affected rotor would rise in a r= otary=20 with dual plugs/coils per rotor. A single dead plug from fouling or oth= er=20 causes could also provide the same result.

Make Sense?
Dave = (a=20 lingering former rotorhead)

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