X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-qy0-f12.google.com ([209.85.221.12] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3500774 for flyrotary@lancaironline.net; Thu, 19 Feb 2009 10:49:01 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.221.12; envelope-from=rwstracy@gmail.com Received: by qyk5 with SMTP id 5so993202qyk.19 for ; Thu, 19 Feb 2009 07:48:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=V52GOlaQfGehd698VYKxXcPy73WD6KDG/RZdThPVUB8=; b=watk9YYVBLEyEAiaJJ1tg/2mEHTbYvTiyguztdkP4kG9qG8/+i21oZb/EoT3tfP9OQ K3u+kux7eiFq1puSC0A4hAdkQkjO2Tik7pLLI47MPEBIJEdjh95RxLLbwDYvmM8N9MBj coYFb6ifac8vsTrAbioYvylnEQ6qpI9LVwptQ= 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=oVQ2M+WO3g9FZKZICvQ3z3+DejvyQMAPFfQdKl+m5JCaZiwK8f7IvKGVYA/mDwQmzT TU8d8ijj/zwqjGA+oEWXkZRoATyPqxLLT5guZs5Qw6o8sw4j9LQClHChgsZ3tSaGivoK il62BtR2bgHF6p7ayb9TWxr936VOhUQHDVzk8= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.53.203 with SMTP id n11mr13373417qag.192.1235058505453; Thu, 19 Feb 2009 07:48:25 -0800 (PST) In-Reply-To: References: Date: Thu, 19 Feb 2009 10:48:25 -0500 X-Google-Sender-Auth: 72be161cbf11cdce Message-ID: <1b4b137c0902190748v9d440eak9c17388af63a46ba@mail.gmail.com> Subject: Re: [FlyRotary] Staging Bog and Lean mixture From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015175cdba07e90020463477774 --0015175cdba07e90020463477774 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Hi Ed, The method you used will work fine for eliminating the staging bog. There have been enough comments on this subject so I might as well get into some of the underlying causes. I mentioned before that it was related to the difference in turn-on and turn-off times of the injectors. The turn-on time is slower than the turn off time, especially with the snubber mod which speeds up turn-off. So, at staging point, the injector pulse width ( IPW ) is cut in half at the same time as the controller enables the secondary injectors. If the t-on and t-off times were equal, the injected fuel would be almost the same as just before staging. BUT, the actual time the injectors are turned on is less than 1/2 of what it was because a higher percentage of the IPW is used up in the t-on injector delay , result is a lean condition. When the throttle is advanced more, the IPW gets longer and so the percentage of IPW "wasted" in the t-on delay is less and the mixture returns to normal. If the staging point is made at a higher manifold pressure (and longer IPW)= , the effect is not as great and that's why tuning out the "bog" is easier. This describes the results with the same flow rate injectors in both primar= y and secondary injectors. When different flow rates are used, the picture gets more complicated. Mode 6 (staging flow rate differential) is even more important in these cases. That's why I now ask for what injectors are used so I can roughly pre-set Mode 6 to make tuning it easier. Also a factor in how difficult the bog is to tune out is the setting of Mod= e 2 (Injection Dynamic Range) but that is a longer subject. Suffice it to say that setting Mode 6 and 2 up prior to MAP tuning in Mode 1 will make your life easier. Hope this helps in understanding what is going on. Tracy On Tue, Feb 17, 2009 at 5:45 PM, Ed Anderson wro= te: > Tracy, for what it's worth, I also see the leaning of the mixture at the > staging point which happens to also coincide with the staging "bog". > > I never knew what was causing the bog and since I don't fly there nor > encounter if during flight, it's never really bothered other than wonderi= ng > about what was causing it. > > > > Once I had a screen display to watch the bin pointer, the staging point a= nd > the air/fuel mixture on the same screen, all at the same time, it became > very clear that leaning of the mixture (or at least that is the indicatio= n > of air/fuel ratio indicator) is happening. > > > > As my bin pointer moves from the hump at the idle (low rpm) region, it > jumps from the low rpm map to the high power/manifold pressure chart abov= e > bin 64 =96 not staged yet. Still no bog, but as it moves a few bins high= er > the air/fuel indicator dives from rich side to off the bottom of the sc= ale > lean and the bog begins. At this point my staging sign goes from 2 inject= ors > to 4 injectors indicating that the EC2 has signaled staging. It last for > approx 3-5 bins (memory's a bit vague here) before the A/F indicator come= s > back up the scale. So something is causing a lean condition. I always > speculated that it had something to do with the air/fuel mixture in the > secondaries making the transition from "dry" to wet - but couldn't quite > convince myself. > > > > The only way I have been able to eliminate the bog is to increase the > richness of that region (3-4 bins) to approx 80-90 (out of 255) which is = not > really a rich setting, but it works and has eliminated the bog. I enrich > each bin's bar watching the A/F indicator as soon as it stops going > completely off the lean end of the scale, I stop and that seems to work f= or > me. > > > > Ed > > > > Ed Anderson > > Rv-6A N494BW Rotary Powered > > Matthews, NC > > eanderson@carolina.rr.com > > http://www.andersonee.com > > http://www.dmack.net/mazda/index.html > > http://www.flyrotary.com/ > > http://members.cox.net/rogersda/rotary/configs.htm#N494BW > > > > > > > __________ Information from ESET NOD32 Antivirus, version of virus > signature database 3267 (20080714) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > --0015175cdba07e90020463477774 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Hi Ed, The method you used will work fine for eliminating the staging bog.&= nbsp;

There have been enough comments on this subject so I might as= well get into some of the underlying causes. 

I mentioned bef= ore that it was related to the difference in turn-on and turn-off times of = the injectors.  The turn-on time is slower than the turn off time, esp= ecially with the snubber mod which speeds up turn-off.   So, = ;  at staging point, the injector pulse width ( IPW )  is cut in = half at the same time as the controller enables the secondary injectors.&nb= sp; If the t-on and t-off times were equal, the injected fuel would be almo= st the same as just before staging.   BUT, the actual time the in= jectors are turned on is less than 1/2 of what it was because a higher perc= entage of the IPW is used up in the t-on injector delay ,  result is a= lean condition.   When the throttle is advanced more, the IPW ge= ts longer and so the percentage of IPW "wasted" in the t-on delay= is less and the mixture returns to normal.

If the staging point is made at a higher manifold pressure (and longer = IPW), the effect is not as great and that's why tuning out the "bo= g" is easier.

This describes the results with the same flow rat= e injectors in both primary and secondary injectors.   When diffe= rent flow rates are used, the picture gets more complicated.   Mo= de 6 (staging flow rate differential) is even more important in these cases= .  That's why I now ask for what injectors are used so I can rough= ly pre-set Mode 6 to make tuning it easier.

Also a factor in how difficult the bog is to tune out is the setting of= Mode 2 (Injection Dynamic Range) but that is a longer subject.   Suff= ice it to say that setting Mode 6 and 2 up prior to MAP tuning in Mode 1 wi= ll make your life easier.

Hope this helps in understanding what is going on.

Tracy

=
On Tue, Feb 17, 2009 at 5:45 PM, Ed Anderson= <eanders= on@carolina.rr.com> wrote:

Tracy, for what it's worth, I also see the leaning of the= mixture at the staging point which happens to also coincide with the staging "bog".

I never knew what was causing the = bog and since I don't fly there nor encounter if during flight, it's never really bothered other than wondering about what was causing it.

 

Once I had a screen display to wat= ch the bin pointer, the staging point and the air/fuel mixture on the same screen,= all at the same time, it became very clear that leaning of the mixture (or at l= east that is the indication of air/fuel ratio indicator) is happening.

 

As my bin pointer moves from the h= ump at the idle (low rpm) region, it jumps from the low rpm map to the high power/manifold pressure chart above bin 64 =96 not staged yet.  Still no bog, but as it moves a few bins higher   the air/fuel indicato= r dives from rich side to off the bottom of the scale lean and the bog begins= . At this point my staging sign goes from 2 injectors to 4 injectors indicating = that the EC2 has signaled staging.  It last for approx 3-5 bins (memory's a bit vague here) before the A/F indicator comes back up the scale.  S= o something is causing a lean condition.  I always speculated that it ha= d something to do with the air/fuel mixture in the secondaries making the transition from "dry" to wet - but couldn't quite convince myself. 

 

The only way I have been able to e= liminate the bog is to increase the richness of that region (3-4 bins) to approx 80-= 90 (out of 255) which is not really a rich setting, but it works and has elimi= nated the bog.  I enrich each bin's bar watching the A/F indicator as soon as it stops going completely off the lean end of the scale, I stop and that= seems to work for me.

 

Ed<= /font>

 

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary= /configs.htm#N494BW

 

 



__________ Information from ESET NOD32 Antivirus, version of virus= signature database 3267 (20080714) __________

The message was check= ed by ESET NOD32 Antivirus.

http://www.eset.com

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