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 3501017 for flyrotary@lancaironline.net; Thu, 19 Feb 2009 12:23:45 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.221.12; envelope-from=rwstracy@gmail.com Received: by qyk5 with SMTP id 5so1082255qyk.19 for ; Thu, 19 Feb 2009 09:23:08 -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=tXL2Q/8C8An+STfawwOsyT0QIrfhBaIl24/WlIJM/Js=; b=KAa6uPoDfXfBYFuTCtsHm3E/fOcHJki0RuBeO1beI4DzNfp9evZbjMIP8YX1JUSBZh 2qgDGi2WKepjsvu4u3er3OmGIKDK8ZxN1niOEJ6HlfxjL7SD5HBswAoKWSysls1xqZ0X Bg0DS/1NeMjAaP/j3thJMPAYKx2D8oQoHrnzc= 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=ast6INUOMqpmNB53VGIRfK+iKrBLqAfJ91H4+a3SOdgVxgIT11TBHWWy4bJEp3jzKi k40V2X2yrPNP4xpyFZKkK9mQ9mIqG2g0HOfcczI+pqVdMA+hwqv/o4N9/d13FQ1ZsaKk ggClim8fGI4pWJjvhSGzobS3yOGUMzar/8ZQo= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.20.77 with SMTP id e13mr8566430qab.44.1235064188504; Thu, 19 Feb 2009 09:23:08 -0800 (PST) In-Reply-To: References: Date: Thu, 19 Feb 2009 12:23:08 -0500 X-Google-Sender-Auth: fa2148d6a1b16cc2 Message-ID: <1b4b137c0902190923s515924d4o357afe6d7a0e6b35@mail.gmail.com> Subject: Re: [FlyRotary] Re: Staging Bog and Lean mixture From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015175cdd003b0a64046348ca76 --0015175cdd003b0a64046348ca76 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit "then applies a nest of algorithms .." Reminds me of the cartoon of the professor at the chalkboard writing some very complex equation. Near the end is the term "Then a miracle happens" :>) Tracy On Thu, Feb 19, 2009 at 11:59 AM, Ed Anderson wrote: > Ok, thanks for the explanation, Tracy. Makes sense to me. > > > So the fuel increase with the secondaries coming on line during staging > trails the shut-off of fuel on the primary injectors by some X amount. So > if I visualize it correctly I would see the fuel flow coming out of the > secondaries increase as a ramp function compared to the step function shut > off of the primaries. All happening in milliseconds or less of course. > > Well, heck, all you have to do is calculate the cross over point where the > ramp function of the secondary meets the primary step function just as it > closes and then start the secondary injectors to opening before the > primaries are closed. How, you do that - given all the interacting > variables, I haven't any ideal - but sounds simple to me (in concept). I > AM > kidding {:>) {:>) > > I think I'll just stick with my current technique as it seems to do the > job. > > > By the way, here is an interesting patient perhaps related to the topic > > United States Patent 7475671 > > A method for compensating fuel injection timing when a torque signal or > throttle command indicates that a transient operation is about to > transpire. > The control adjusts the fuel injection timing in advance of the transient > operation to prevent loss of torque due to change in combustion phase > position. During engine operation in pre-mix mode of combustion, rapid > changes in fueling quantity can affect the combustion angle as well as the > temperature in the combustion chamber, causing late or early combustion > phasing. The present invention anticipates a change in combustion phasing > by > sensing a change in demanded fueling rate. The Engine Control Module (ECM) > then applies a nest of algorithms to advance fuel injection timing during > acceleration or to shorten ignition delay for deceleration by retarding > fuel > injection timing. As the engine returns to steady state operation, the > compensation in injection timing is progressively reduced to zero. > http://www.freepatentsonline.com/7475671.html > > > The phrase I like best in the abstract is ...applies a nest of algorithms > .. > (sounds like a snake's nest to 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 > > > > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On > Behalf Of Tracy Crook > Sent: Thursday, February 19, 2009 10:48 AM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Staging Bog and Lean mixture > > 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 > primary > 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 > Mode > 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 > 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 watch 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 least that is the indication > 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 above bin 64 > - not staged yet. Still no bog, but as it moves a few bins higher the > air/fuel indicator 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. 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 for > 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 > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > --0015175cdd003b0a64046348ca76 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable "then applies a nest of algorithms .."   Reminds me of the c= artoon of the professor at the chalkboard writing some very complex equatio= n.  Near the end is the term "Then a miracle happens"  = :>)

Tracy


On Thu, Feb 19, 2009 at 11:59 A= M, Ed Anderson <eanderson@carolina.rr.com> wrote:
Ok, thanks for the explanation, Tracy.  Makes sense to me.


So the fuel increase with the secondaries coming on line during staging
trails the shut-off of fuel on the primary injectors by some  X amount= .  So
if I visualize it correctly I would see the fuel flow coming out of the
secondaries increase as a ramp function compared to the step function shut<= br> off of the primaries. All happening in milliseconds or less of course.

Well, heck, all you have to do is calculate the cross over point where the<= br> ramp function of the secondary meets the primary step function just as it closes and then start the secondary injectors to opening before the
primaries are closed.  How, you do that - given all the interacting variables, I haven't any ideal - but sounds simple to me (in concept). =  I AM
kidding {:>) {:>)

I think I'll just stick with my current technique as it seems to do the= job.


By the way, here is an interesting patient perhaps related to the topic

United States Patent 7475671

A method for compensating fuel injection timing when a torque signal or
throttle command indicates that a transient operation is about to transpire= .
The control adjusts the fuel injection timing in advance of the transient operation to prevent loss of torque due to change in combustion phase
position. During engine operation in pre-mix mode of combustion, rapid
changes in fueling quantity can affect the combustion angle as well as the<= br> temperature in the combustion chamber, causing late or early combustion
phasing. The present invention anticipates a change in combustion phasing b= y
sensing a change in demanded fueling rate. The Engine Control Module (ECM)<= br> then applies a nest of algorithms to advance fuel injection timing during acceleration or to shorten ignition delay for deceleration by retarding fue= l
injection timing. As the engine returns to steady state operation, the
compensation in injection timing is progressively reduced to zero.
http://www.freepatentsonline.com/7475671.html


The phrase I like best in the abstract is ...applies a nest of algorithms .= .
(sounds like a snake's nest to me {:>)).

Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com<= br> http://www.anderson= ee.com
http://= www.dmack.net/mazda/index.html
http://www.flyrotar= y.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW<= br> <http://members.cox.net/rogersda/rotary/configs.htm>
 <http://www.dmack.net/mazda/index.html>

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Tracy Crook
Sent: Thursday, February 19, 2009 10:48 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Staging Bog and Lean mixture

Hi Ed, The method you used will work fine for eliminating the staging bog.<= br>
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 o= n 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.   Wh= en 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 nor= mal.

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 pic= ture
gets more complicated.   Mode 6 (staging flow rate differential) is ev= en
more important in these cases.  That's why I now ask for what inje= ctors 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 <eanderson@carolina.rr.com>
wrote:
Tracy, for what it's worth, I also see the leaning of the mixture at th= e
staging point which happens to also coincide with the staging "bog&quo= t;.
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 wonde= ring
about what was causing it.

Once I had a screen display to watch 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 least that is the indication<= br> of air/fuel ratio indicator) is happening.

As my bin pointer moves from the hump at the idle (low rpm) region, it jump= s
from the low rpm map to the high power/manifold pressure chart above bin 64=
- not staged yet.  Still no bog, but as it moves a few bins higher &nb= sp; the
air/fuel indicator 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 a= pprox
3-5 bins (memory's a bit vague here) before the A/F indicator comes bac= k up
the scale.  So something is causing a lean condition.  I always s= peculated
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 no= t
really a rich setting, but it works and has eliminated the bog.  I enr= ich
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

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com<= br> http://www.anderson= ee.com
http://= www.dmack.net/mazda/index.html
http://www.flyrotar= y.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW<= br> <http://members.cox.net/rogersda/rotary/configs.htm>
 <http://www.dmack.net/mazda/index.html>



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

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

--
Homepage:  htt= p://www.flyrotary.com/
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