X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nm8.bullet.mail.sp2.yahoo.com ([98.139.91.78] verified) by logan.com (CommuniGate Pro SMTP 5.4c2o) with SMTP id 4893057 for flyrotary@lancaironline.net; Sun, 06 Mar 2011 20:06:08 -0500 Received-SPF: none receiver=logan.com; client-ip=98.139.91.78; envelope-from=keltro@att.net Received: from [98.139.91.66] by nm8.bullet.mail.sp2.yahoo.com with NNFMP; 07 Mar 2011 01:05:31 -0000 Received: from [98.139.91.47] by tm6.bullet.mail.sp2.yahoo.com with NNFMP; 07 Mar 2011 01:05:31 -0000 Received: from [127.0.0.1] by omp1047.mail.sp2.yahoo.com with NNFMP; 07 Mar 2011 01:05:31 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 916391.52278.bm@omp1047.mail.sp2.yahoo.com Received: (qmail 74194 invoked by uid 60001); 7 Mar 2011 01:05:31 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1299459931; bh=ziM/zg318hQGBDonu4oVwseKONCX9zh474o5PE2nUpU=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=4D1o8wk5A+o4kFL5ZnVFGq5uf3ihBYrrRSdoMQqfFjENK/NVLSLQQRNg0B1OVZcuFTLun89q67bzIu86GGLkiJZSXtPXK6PAOkGcy8hPk5hEz38XyHnrHsfYog8PuboT7i9+UeTzZj5cE+5VVwK353nDG0huCMxggDnjRWY5YTQ= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=att.net; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=0CAX2Pce+zjCXE5RbxphNBVvcJgS0Gx2bXwN50OTcqVwdk82a2R8P3JvifYvZM8uOcys2VPihbnst49dPMP4xIBMwa2ljUVtZsg07zSV/4QsOWuOHkbOW7FDu8Tat+rbQ5IrSyZtOA9azfQk+ZUsYo6Y4mMXLhwC+kQSiNOR0qU=; Message-ID: <775066.73032.qm@web83915.mail.sp1.yahoo.com> X-YMail-OSG: x55XhGYVM1nxYkuFJSt_dC85byZh94KlKDF7zUT5IA.NSCE Q2FQ6EOglZh6Mav5GVQSI1A2OM9dZsrlu0o4vItNMFqk7DgsKsivJP5FLeag mghhtRJ1gWSL5wd3vVZRZDz5cSGzVVUhNiLsXw7vsFuiKjO1n3vPO.tyeQrs DOilS5aDERP.zGcY3LhxlKQ86Cpgczhu3PeoxA5J8iLCaEU6HFYdjGi7gFxe 4dQvnr8plfMqgGglvzJGallTWoUHgf4AWqTfW1LrtHWayE9GkY8n7agAmyKy vqrMJ Received: from [208.114.44.149] by web83915.mail.sp1.yahoo.com via HTTP; Sun, 06 Mar 2011 17:05:31 PST X-Mailer: YahooMailRC/559 YahooMailWebService/0.8.109.292656 References: Date: Sun, 6 Mar 2011 17:05:31 -0800 (PST) From: Kelly Troyer Subject: staging and tuning To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1009828983-1299459931=:73032" --0-1009828983-1299459931=:73032 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Steve,=0A=A0=A0=A0 Excellent info !!.........We are lucky to have such tale= nt in the =0Agroup..............Even I can=0Anow better grasp how the EC2 w= orks and this info will really help those of us =0Athat do not=0Ahave the t= echnical expertise with our tuning struggles !!..............=0A=0AThanks,= =A0=0AKelly Troyer=0A"DYKE DELTA JD2" (Eventually)=0A"13B ROTARY"_ Engine= =0A"RWS"_RD1C/EC2/EM2=0A"MISTRAL"_Backplate/Oil Manifold=0A"TURBONETICS"_TO= 4E50 Turbo=0A=0A=0A=0A=0A________________________________=0AFrom: Steven W.= Boese =0ATo: Rotary motors in aircraft =0ASent: Sun, March 6, 2011 6:49:36 PM=0ASubject: [FlyRotary] st= aging and tuning=0A=0ABill and anyone else interested:=0A=0AThe issues invo= lved with mixture changes when the EC2 controller stages can be =0Aundersto= od by considering two simple concepts:=0A=0A1. The first is the concept of = injector lag, also referred to as injector =0Alatency and injector dead tim= e, as well as other names.=A0 The fuel injectors are =0Anot perfect.=A0 The= y do not instantaneously respond to the controller pulse.=A0 That =0Ais, th= ey take a measurable time to open after the application of the pulse and = =0Athey take a measurable time to close after the pulse ends.=A0 These two = times are =0Anot equal and the result is that the injector flows fuel for a= smaller period of =0Atime than the injector pulse width.=A0 In addition, t= he injector flow rate is =0Achanging during the opening and closing time pe= riods.=A0 Measurements of the =0Aamount of fuel delivered as a function of = pulse width show that the deficit in =0Athe amount of fuel delivered for an= y pulse is the same whether the pulse width =0Ais long or short.=A0 For sto= ck 40 lb Mazda injectors with a fuel pressure of 40 =0Apsi and a system vol= tage of 13 volts, this loss in the amount of fuel delivered =0Acorresponds = to an injector lag or dead time of about 1.2 ms.=0A=0AThis 1.2 ms is not tr= ivial.=A0 Consider a rotary engine running at 6000 rpm.=A0 The =0Atime it t= akes for one revolution is 10 ms.=A0 Limiting the injector pulse to an =0A8= 0% duty cycle limits the injector pulse width to 8 ms.=A0 The effect of the= =0Ainjector lag is to decrease the amount of fuel delivered by 1.2/8 x 100= or 15% =0Aat 8 ms pulse width,=A0 1.2/4 x 100 or 30% at 4 ms pulse width, = and 1.2/1.2 x 100 =0Aor 100% at 1.2 ms pulse width.=A0 It is obvious that t= he shorter the pulse width, =0Athe larger the fuel deficit.=0A=0A2. The sec= ond concept to realize is that the EC2 controller does not take =0Ainjector= lag into account.=A0 This has been demonstrated with my EC2's at default = =0Asettings by measuring the injector pulse width on either side of the sta= ging =0Atransition.=A0 It has also been demonstrated by pulse width measure= ments taken =0Awhen engaging the injector back up function where the change= from using two to =0Ausing four injectors is forced to occur without a cha= nge in manifold pressure or =0Achange in MAP table address.=A0 These measur= ements show that, before tuning, the =0AEC2 staging transition is a transit= ion to using all the injectors at half the =0Apre-transition pulse width.= =A0 The essential point here is that even if the =0Aprimary and secondary i= njectors are the same size, staging, by using twice as =0Amany injectors at= half the pulse width does not result in the same fuel flow, =0Abut rather = a substantial fuel flow decrease.=A0 Using the above data, this is =0Aeasil= y seen by considering what would happen if staging took place at an initial= =0Apulse width of 1.2 ms.=A0 After staging, the fuel flow would then be ze= ro.=0A=0A=0ABefore tuning and with primary and secondary injectors of the s= ame size, the =0Aeffect of injector lag is always for the controller to del= iver less fuel than it =0Acalculates as being needed.=A0 This problem becom= es progressively worse as the =0Ainjector pulse width decreases.=A0 When th= e secondary injector flow rating is =0Alarger than that of the primary inje= ctors, the mixture change due to staging, =0Awhile predictable, is not intu= itive.=A0 This is because the tendency to go lean =0Adue to the injector la= g effect accompanying the pulse width being cut in half is =0Anow combined = with the tendency to go rich due to the two larger injectors now in =0Ause.= =A0 Whether the mixture goes leaner, richer, or is unchanged upon staging = =0Adepends not only on the difference in the primary and secondary injector= flow =0Aratings but also upon the conditions (initial pulse width) under w= hich staging =0Atakes place.=0A=0AThe discussion which follows is for the c= ase of equal sized primary and =0Asecondary injectors and initial tuning st= arting with default parameters:=0A=0AThe percent decrease in fuel flow upon= staging is most severe for low initial =0Afuel flow rates.=A0 This explain= s the difficulty in achieving a smooth staging =0Aprocess if the staging th= reshold is set too low.=A0 Even for reasonable initial =0Afuel flow rates i= n the range of 6 to 10 gal/hr, the fuel flow will decrease =0Asignificantly= .=A0 If the mixture is rich enough when staging takes place, the =0Adecreas= e in fuel flow may not result in a large change in engine power output.=A0 = =0AHowever, if the mixture is already somewhat lean when staging occurs, th= e =0Amixture may become very lean and result in a marked decrease in power.= =0A=0AI've used three methods to compensate for the injector lag.=0A=0A1.= =A0 The first method is to follow the instructions in the manual.=A0 Tuning= is =0Astarted by adjusting modes 3 and 2.=A0 After modes 3 and 2 have been= adjusted, =0Athen mode 1 or 9 is used to adjust the mixture correction tab= le.=A0 Tuning the =0Amixture correction table can compensate for the fuel f= low decrease on staging =0Acaused by injector lag.=A0 This results in a dis= continuity in the correction table =0Aat staging.=A0 Since defining the ste= p in the mixture table can be difficult, =0Aprogramming the mixture somewha= t rich across this region is helpful.=A0 Cruise =0Aoperation at MAP values = close to the staging threshold then simply requires some =0Aadjustment of t= he manual mixture control.=A0 Because of the step in the mixture =0Atable a= t the staging point, changing the staging threshold also requires =0Aretuni= ng of the mixture table in this region. Tuning the rest of the table =0Acom= pensates for other factors such as changes in volumetric efficiency in =0Aa= ddition to injector lag.=A0 Injector lag affects tuning of the entire table= =0Aalthough it is just not as obvious as its effect on staging.=0A=0A2.=A0= A second way to compensate for the effect of injector lag on staging is to= =0Ause the mode 6 secondary injector differential adjustment even with pri= mary and =0Asecondary injectors of matched flow rates.=A0 Since the mode 6 = setting only has =0Aeffect above the staging threshold, and since the effec= t of injector lag is to =0Amake the injectors act as if they became smaller= upon staging, mode 6 can be =0Aused to eliminate the step in the mixture c= orrection table.=A0 This is possible =0Abecause mode 6 has the ability to c= ompensate for smaller as well as larger =0Asecondary injectors compared to = the primaries.=A0 Compensation for the effect of =0Ainjector lag and other = factors is still necessary throughout the table, but the =0Achanges are gra= dual and much easier to implement than a discontinuity.=A0 This =0Amethod r= emoves the injector lag effect upon staging and works quite well.=0A=0AThe = tuning procedure then becomes the same whether the primary and secondary = =0Ainjector flow rates are different or identical:=0A=0Aa.=A0 Set the stagi= ng threshold at a MAP corresponding to the high end of the =0Aprimary injec= tor flow limit using mode 7.=A0 (For 40 lb injectors, about 20" MAP =0Awork= s well.)=0A=0Ab.=A0 Adjust Mode 3 to get a mid scale O2 sensor reading at a= MAP just below the =0Astaging threshold MAP.=0A=0Ac.=A0 Adjust mode 6 to g= et a mid scale O2 sensor reading at a MAP just above the =0Astaging thresho= ld MAP.=0A=0Ad.=A0 Adjust mode 2 for best operation at minimum idle MAP.=0A= =0Ae.=A0 Adjust the mixture table throughout the useable MAP range using mo= de 1 or 9 =0Ato keep the O2 sensor reading mid scale.=A0 (To be honest, I s= kip step "e" and =0Asimply use the manual mixture control to adjust the mix= ture in cruise.)=0A=0A=0ASteve Boese=0ARV6A 1986 13B NA RD1A EC2=0A=0A=0A= =0A=0A--=0AHomepage:=A0 http://www.flyrotary.com/=0AArchive and UnSub:=A0 h= ttp://mail.lancaironline.net:81/lists/flyrotary/List.html=0A --0-1009828983-1299459931=:73032 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
=0A
Steve,
=0A
    Excellent in= fo !!.........We are lucky to have such talent in the group..............Ev= en I can
=0A
now better grasp how the EC2 works and this info will= really help those of us that do not
=0A
have the technical expert= ise with our tuning struggles !!..............
=0A
 
=0A=
Thanks, 
=0A

Kelly Troyer
"DYKE = DELTA JD2" (Eventually)

=0A

"13B= ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold<= /P>=0A

"TURBONETICS"_TO4E50 Turbo

=0A

=0A

=0A
=0A
=0AFrom: Steven W. Boese <SBoese@uwyo.edu>
<= SPAN style=3D"FONT-WEIGHT: bold">To: Rotary motors in aircraft &= lt;flyrotary@lancaironline.net>
= Sent: Sun, March 6, 2011 6:49:36 PM
Subject: [FlyRotary] staging and tuning
Bill and anyone else interested:

The issues involved with mixture = changes when the EC2 controller stages can be understood by considering two= simple concepts:

1. The first is the concept of injector lag, also = referred to as injector latency and injector dead time, as well as other na= mes.  The fuel injectors are not perfect.  They do not instantane= ously respond to the controller pulse.  That is, they take a measurabl= e time to open after the application of the pulse and they take a measurabl= e time to close after the pulse ends.  These two times are not equal and the result is that the injector flows fuel for= a smaller period of time than the injector pulse width.  In addition,= the injector flow rate is changing during the opening and closing time per= iods.  Measurements of the amount of fuel delivered as a function of p= ulse width show that the deficit in the amount of fuel delivered for any pu= lse is the same whether the pulse width is long or short.  For stock 4= 0 lb Mazda injectors with a fuel pressure of 40 psi and a system voltage of= 13 volts, this loss in the amount of fuel delivered corresponds to an inje= ctor lag or dead time of about 1.2 ms.

This 1.2 ms is not trivial.&n= bsp; Consider a rotary engine running at 6000 rpm.  The time it takes = for one revolution is 10 ms.  Limiting the injector pulse to an 80% du= ty cycle limits the injector pulse width to 8 ms.  The effect of the i= njector lag is to decrease the amount of fuel delivered by 1.2/8 x 100 or 15% at 8 ms pulse width,  1.2/4 x 100 or 30% at 4 ms pulse wid= th, and 1.2/1.2 x 100 or 100% at 1.2 ms pulse width.  It is obvious th= at the shorter the pulse width, the larger the fuel deficit.

2. The = second concept to realize is that the EC2 controller does not take injector= lag into account.  This has been demonstrated with my EC2's at defaul= t settings by measuring the injector pulse width on either side of the stag= ing transition.  It has also been demonstrated by pulse width measurem= ents taken when engaging the injector back up function where the change fro= m using two to using four injectors is forced to occur without a change in = manifold pressure or change in MAP table address.  These measurements = show that, before tuning, the EC2 staging transition is a transition to usi= ng all the injectors at half the pre-transition pulse width.  The esse= ntial point here is that even if the primary and secondary injectors are the same size, staging, by using twice as many injectors at half the p= ulse width does not result in the same fuel flow, but rather a substantial = fuel flow decrease.  Using the above data, this is easily seen by cons= idering what would happen if staging took place at an initial pulse width o= f 1.2 ms.  After staging, the fuel flow would then be zero.

Before tuning and with primary and secondary injectors of the same size, t= he effect of injector lag is always for the controller to deliver less fuel= than it calculates as being needed.  This problem becomes progressive= ly worse as the injector pulse width decreases.  When the secondary in= jector flow rating is larger than that of the primary injectors, the mixtur= e change due to staging, while predictable, is not intuitive.  This is= because the tendency to go lean due to the injector lag effect accompanyin= g the pulse width being cut in half is now combined with the tendency to go rich due to the two larger injectors now in use.  Whet= her the mixture goes leaner, richer, or is unchanged upon staging depends n= ot only on the difference in the primary and secondary injector flow rating= s but also upon the conditions (initial pulse width) under which staging ta= kes place.

The discussion which follows is for the case of equal siz= ed primary and secondary injectors and initial tuning starting with default= parameters:

The percent decrease in fuel flow upon staging is most = severe for low initial fuel flow rates.  This explains the difficulty = in achieving a smooth staging process if the staging threshold is set too l= ow.  Even for reasonable initial fuel flow rates in the range of 6 to = 10 gal/hr, the fuel flow will decrease significantly.  If the mixture = is rich enough when staging takes place, the decrease in fuel flow may not = result in a large change in engine power output.  However, if the mixture is already somewhat lean when staging occurs, the mixture may = become very lean and result in a marked decrease in power.

I've used= three methods to compensate for the injector lag.

1.  The firs= t method is to follow the instructions in the manual.  Tuning is start= ed by adjusting modes 3 and 2.  After modes 3 and 2 have been adjusted= , then mode 1 or 9 is used to adjust the mixture correction table.  Tu= ning the mixture correction table can compensate for the fuel flow decrease= on staging caused by injector lag.  This results in a discontinuity i= n the correction table at staging.  Since defining the step in the mix= ture table can be difficult, programming the mixture somewhat rich across t= his region is helpful.  Cruise operation at MAP values close to the st= aging threshold then simply requires some adjustment of the manual mixture = control.  Because of the step in the mixture table at the staging point, changing the staging threshold also requires retuning of th= e mixture table in this region. Tuning the rest of the table compensates fo= r other factors such as changes in volumetric efficiency in addition to inj= ector lag.  Injector lag affects tuning of the entire table although i= t is just not as obvious as its effect on staging.

2.  A second= way to compensate for the effect of injector lag on staging is to use the = mode 6 secondary injector differential adjustment even with primary and sec= ondary injectors of matched flow rates.  Since the mode 6 setting only= has effect above the staging threshold, and since the effect of injector l= ag is to make the injectors act as if they became smaller upon staging, mod= e 6 can be used to eliminate the step in the mixture correction table. = ; This is possible because mode 6 has the ability to compensate for smaller= as well as larger secondary injectors compared to the primaries.  Compensation for the effect of injector lag and other fac= tors is still necessary throughout the table, but the changes are gradual a= nd much easier to implement than a discontinuity.  This method removes= the injector lag effect upon staging and works quite well.

The tuni= ng procedure then becomes the same whether the primary and secondary inject= or flow rates are different or identical:

a.  Set the staging t= hreshold at a MAP corresponding to the high end of the primary injector flo= w limit using mode 7.  (For 40 lb injectors, about 20" MAP works well.= )

b.  Adjust Mode 3 to get a mid scale O2 sensor reading at a M= AP just below the staging threshold MAP.

c.  Adjust mode 6 to g= et a mid scale O2 sensor reading at a MAP just above the staging threshold = MAP.

d.  Adjust mode 2 for best operation at minimum idle MAP.<= BR>
e.  Adjust the mixture table throughout the useable MAP range using mode 1 or 9 to keep the O2 sensor reading mid scale.  (To= be honest, I skip step "e" and simply use the manual mixture control to ad= just the mixture in cruise.)


Steve Boese
RV6A 1986 13B NA RD1= A EC2




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