X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-wy0-f180.google.com ([74.125.82.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4587995 for flyrotary@lancaironline.net; Mon, 22 Nov 2010 08:57:44 -0500 Received-SPF: pass receiver=logan.com; client-ip=74.125.82.180; envelope-from=rwstracy@gmail.com Received: by wya21 with SMTP id 21so7136975wya.25 for ; Mon, 22 Nov 2010 05:57:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:sender:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:content-type; bh=vVrwT16+Egd47cQaskDsVa5LBmDNxhBUvRtMu38q3b4=; b=Kf9+d1SOYEN6B4R14VnZDmdk7AdDgQ7rPzBkIpMAKg8coR61+yZO0GpH15dXmFTweB IIKfeGDunB4H5MjAYK+ARvPDs1G3JS1eeW8iK3OZDzdopdY5oMsDrkRu4khb+0tdjQlc Bg8Ynjsqgf5J/aTl4D3YAPYcuvaO0eVrULX+c= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=L3cXlXIkSLA0d/6I1Kgm95KcoyLxvy6gltFCe6es0HgFXdBwPgUApNuRdSPR8KM2tQ /pPR0539Q/aur90Lt3c476dntxvx/Di2EQz90GC70KxASk0cMQksxRnPm4T8VAAA/kIL cRwqFqmva3wMfTR1NzRRqWrhoSk8nZuTJ5TQA= MIME-Version: 1.0 Received: by 10.216.35.133 with SMTP id u5mr4781656wea.72.1290434222589; Mon, 22 Nov 2010 05:57:02 -0800 (PST) Sender: rwstracy@gmail.com Received: by 10.216.21.145 with HTTP; Mon, 22 Nov 2010 05:57:02 -0800 (PST) In-Reply-To: References: Date: Mon, 22 Nov 2010 08:57:02 -0500 X-Google-Sender-Auth: jK8x6kuOMMF9WoldEJ_um3J35z8 Message-ID: Subject: Re: [FlyRotary] Re: Trailing Coil Disable to Turbo too? Was: N20 From: Tracy To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0016365eec1271872c0495a4a14d --0016365eec1271872c0495a4a14d Content-Type: text/plain; charset=ISO-8859-1 Lynn's answer was better than any one I can give. I have no experience with boosted engines. Interesting comments about the ignition split. The good news is that the EC2/3 does not use any split. I've never seen any convincing data that indicates that ignition split helps anything other than emissions. I do know that under typical conditions in our application, the split causes a loss of power. The loss is pretty significant in the event of leading coil failure. Tracy On Mon, Nov 22, 2010 at 1:41 AM, wrote: > In a message dated 11/21/2010 4:13:32 P.M. Eastern Standard Time, > wdleonard@gmail.com writes: > > This is the first I am hearing about disabling the trailing coils for > prevention of detonation. Should I be doing this when I am at high boost as > well. Right now I seem to be able to run 45" without issue but may start > pushing that a little. Can you guide me to the background? > -- > David Leonard > > > Detonation is an auto ignition of compressed gasses after the planned > ignition event. If you have two plugs and one plug fires later than the > leading (ignition split) the second plug starts looking like detonation. > > Worse for higher boost. Worse for wider split. > > Since the second event (auto ignition) occurs in an area away from the > leading plug it is in a higher pressure and with fuel and air molecules > closer together and at a higher temperature. So combustion is more energetic > with higher than normal flame front speeds. The pressure spikes generated > may overcome the oil film on bearings, or break apex seals, or, rings and > ring lands in piston engines. Very bad mojo. > > Detonation is charge temperature dependant. So cooler intake air, richer > mixture (well rich of peak EGT) as in take off and climb. (Fuel cooling) > Cooler oil (rotor face temps) and cooler housing walls (bigger radiator). > Higher octane fuel. Octane is a measurement of detonation resistance. Higher > number is better. Very lean mixtures with their low flame speeds can mimic > higher octane fuel. > > The rotary with its huge combustion chamber and cool charge temps is more > resistant to detonation than is a piston engine. Until you pour on the > boost. Modest boost and almost nothing changes. Weekend killer....hold my > beer and watch this kind of boost.... You can get 800 HP from a 13B but > engine life may be in seconds. The added fuel and air produces a bigger > engine. Let us say that you double the fuel and air processed per > revolution. That would be the same as an engine of twice the swept volume, > correct? > > But, the combustion chamber remains the same size, so the effective > compression ratio has gone way up. Flame speed may more than double. Since > we want best chamber pressure at about 45-50 degrees after TDC, the ignition > timing must be reduced a bunch. > > Racing Beat says no split timing at high boost. Engine development is at 10 > degrees of total advance. Racing at high boost is at 12 degrees of total > advance. Crazed drag racers may be running all of the timing after TDC. The > lure of 800 HP you know. > > I have no knowledge of boosted rotary engines. It is a fad. It will go > away. > > Lynn E. Hanover > --0016365eec1271872c0495a4a14d Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Lynn's answer was better than any one I can give.=A0=A0 I have no exper= ience with boosted engines.

=A0 Interesting comments about the ignit= ion split.=A0 The good news is that the EC2/3 does not use any split.=A0 I&= #39;ve never seen any convincing data that indicates that ignition split he= lps anything other than emissions.=A0 I do know that under typical conditio= ns in our application, the split causes a loss of power.=A0=A0 The loss is = pretty significant in the event of leading coil failure.

Tracy


On Mon, Nov 22, 2010 at 1:4= 1 AM, <Lehanover= @aol.com> wrote:
In a message dated 11/21/2010 4:13:32 P.M. Eastern Standard Time,=20 wdleonard@gmail.co= m writes:
This is the first I am hearing about disabling the trailing coils fo= r=20 prevention of detonation.=A0 Should I be doing this when I am at high boo= st=20 as well.=A0 Right now I seem to be able to run 45" without issue but= may=20 start pushing that a little.=A0 Can you guide me to the=20 background?
--
David Leonard

=A0
Detonation is an auto ignition of compressed gasses after the planned= =20 ignition event. If you have two plugs and one plug fires later than the lea= ding=20 (ignition split) the second plug starts looking like detonation.
=A0
Worse for higher boost. Worse for wider split.
=A0
Since the second event (auto ignition) occurs in an area away from the= =20 leading plug=A0it is in a higher pressure and with fuel and air molecules= =20 closer together and at a higher temperature. So combustion is more energeti= c=20 with higher than normal flame front speeds. The pressure spikes generated m= ay=20 overcome the oil film on bearings, or break apex seals, or, rings and ring = lands=20 in piston engines. Very bad mojo.
=A0
Detonation is charge temperature dependant. So cooler intake air, rich= er=20 mixture (well rich of peak EGT) as in take off and climb. (Fuel cooling) Co= oler=20 oil (rotor face temps) and cooler housing walls (bigger radiator). Higher o= ctane=20 fuel. Octane is a measurement of detonation resistance. Higher number is be= tter.=20 Very lean mixtures with their low flame speeds can mimic higher octane fuel= .=20
=A0
The rotary with its huge combustion chamber and cool charge temps is m= ore=20 resistant to detonation than is a piston engine. Until you pour on the boos= t.=20 Modest boost and almost nothing changes. Weekend killer....hold my beer and= =20 watch this kind of boost.... You can get 800 HP from a 13B but engine life = may=20 be in seconds. The added fuel and air produces a bigger engine. Let us say = that=20 you double the fuel and air processed per revolution. That would be the sam= e as=20 an engine of twice the swept volume, correct?
=A0
But, the combustion chamber remains the same size, so the effective=20 compression ratio has gone way up. Flame speed may more than double. Since = we=20 want best chamber pressure at about 45-50 degrees after TDC, the ignition t= iming=20 must be reduced=A0a bunch.
=A0
Racing Beat says no split timing at high boost. Engine development is = at 10=20 degrees of total advance. Racing at high boost is at 12 degrees of total=20 advance. =A0Crazed drag racers may be running all of the timing after TDC.= =20 The lure of 800 HP you know.
=A0
I have no knowledge of boosted rotary engines. It is a fad. It will go= =20 away.
=A0
Lynn E. Hanover=A0=A0

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