X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 64 [XX] (50%) BODY: contains text similar to "low payment" (25%) SPAMTRICK: obfuscated phone number (-25%) BODY: correction: likely legitimate obfuscated series of numbers Return-Path: Received: from bay0-omc3-s33.bay0.hotmail.com ([65.54.246.233] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1915612 for flyrotary@lancaironline.net; Sun, 11 Mar 2007 19:54:55 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.54.246.233; envelope-from=lors01@msn.com Received: from hotmail.com ([65.54.250.88]) by bay0-omc3-s33.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.2668); Sun, 11 Mar 2007 16:54:08 -0700 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sun, 11 Mar 2007 16:54:08 -0700 Message-ID: Received: from 4.171.150.73 by BAY115-DAV16.phx.gbl with DAV; Sun, 11 Mar 2007 23:54:06 +0000 X-Originating-IP: [4.171.150.73] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: A solution? was : The truth??? / Injector flow rate mystery solved Date: Sun, 11 Mar 2007 19:54:00 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_017B_01C76417.032043A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.50.0034.2000 Seal-Send-Time: Sun, 11 Mar 2007 19:54:00 -0400 X-OriginalArrivalTime: 11 Mar 2007 23:54:08.0682 (UTC) FILETIME=[8F33A0A0:01C76438] Return-Path: lors01@msn.com This is a multi-part message in MIME format. ------=_NextPart_000_017B_01C76417.032043A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageSteve has a good handle on the factors involved here.=20 His RC snubber definitely addresses the root cause of the problem and = works. Note that this requires removing or disabling the diode clamps. = My job now is to come up with a fix that accomplishes the same thing = and is easy as possible to implement AND to verify that there are no = other 'gotchas'. The first part was relatively easy. It involves = cutting one trace on the circuit board and adding a single component = (resistor [or a MOV as Marv suggested]) in a position that is easy to = retrofit. Completed the bench and flight testing yesterday with = excellent results. =20 The second part (checking for 'gotchas') was the hard part. A detailed = report would take more time than I've got but here are the basics. =20 Compensating for the shorter (actual) injector open times requires that = the EC2 increase the injector pulse widths. The means to do this are = already there in Mode 3 (injector flow rate adjustment). It does = require a big change (about 53% in my case with the Renesis saturated = injectors) in the Mode 3 constant. It was at 150 and had to be = increased to 230. This alone was enough to get the engine mixture back = in range and safe to fly. I spent about 3 minutes on the ground coarse = tuning the MAP table, then took off and let the EM2 autotune do the fine = tuning. All went well until I got to the full throttle / high speed = part of the test. When the engine reached about 6000 rpm the engine = went into rev-limit (ignition & fuel cut until revs dropped below limit = then switches back on until rev limit reached again). Very = disconcerting when in-flight. Engine ran fine when throttled back. = This was NOT due to the normal rev limiter function which is programmed = at 7500 rpm. Much geeky software debugging later I found that it was caused as a side = effect of altering the IPW (injector pulse width) clock beyond it's = normal range. This clock is also used in another function which didn't = like this. This particular bug only affects the Renesis and other = single sensor engines. Very easy software fix once it was found. 2nd = & 3rd gen 13Bs and 20Bs use 2 sensors so are not affected by this. = Still checking the dozen or so other engine types that the EC2 is made = for. The final result on my engine (Renesis) did not show any dramatic change = in engine performance or difference in idle smoothness. As Ed noted, = the small primary injectors (290 cc) make it more tolerant of the pulse = stretching effect of the diode clamps. I also got reasonably good idle = on my 2nd gen 13B using 440 cc injectors. The bigger they are, the more = difficult they will be to tune and the more susceptible they will be to = idle problems at low speed.=20 On the plus side, there were fewer and smaller changes (from nominal) = needed in the map table. This made tuning easier and faster. I will = probably be able to idle slower but I will have to get under the cowl = and adjust the stop on throttle body to try it. It idles at 1600 rpm = very smoothly (before & after the change). Sudden power chops to idle when entering the pattern go noticeably = smoother now. I was used to the occasional burble & pop similar to what = you've probably heard from P-51s and other warbirds in the pattern at = fly-ins. =20 More details to follow. Tracy ----- Original Message -----=20 From: Steven Boese=20 To: Rotary motors in aircraft=20 Sent: Sunday, March 11, 2007 2:21 PM Subject: [FlyRotary] Re: A solution? was : The truth??? / Injector = flow rate mystery solved Ed and Joe, =20 The diode in the EC2 allows the current from the collapse of the = injector magnetic field to flow to the positive supply rail (~14V); it = doesn't oppose this. A resistor allowing this current to flow would = also result in a close delay since the current flowing is what maintains = the magnetic field during this delay. What is needed is a way to = decrease the rate of voltage rise just after the EC2 pulse ends so = arcing in the A/B selection relay is suppressed. After the relay = contacts open enough that an arc is no longer possible (which shouldn't = take long) an open circuit condition now would allow the injector to = close quickly. The arcing may or may not be a problem any given time = the relay is opened since the timing of the end of the EC2 pulse and the = opening of the relay are independent and arbitrary. One possible = solution is a RC snubber rather than the resistor that Joe proposed. I = think Tracy is working on checking this out. I have installed this in = my plane and it works. Tracy, however can do a much more thorough job = of evaluating this and be sure the change is reliable. Let's give him a = chance to do this before we do something we wish we hadn't. =20 Steve =20 =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Ed Anderson Sent: Sunday, March 11, 2007 9:16 AM To: Rotary motors in aircraft Subject: [FlyRotary] A solution? was : The truth??? / Injector flow = rate mystery solved =20 Sounds like a reasonable approach to me Joe. A pull-down resistor = would be relatively easy for me to install - I have the resistor pack = required for the peak-hold type injectors. So I could easily place four = additional resistors in that box. =20 If I understand you (please correct me if I don't), the pull down = resistor should go between the injector and the EC2 sinking terminals. = That way the current induced when the intended pulse terminates and the = magnetic field collapses will have a path to ground rather than being = opposed by the diode in the Ec2. =20 The value of said resistor could be around 100 ohms. Since the = induced voltage could reach from 50 - 100+ volts an 100 ohm resistor = could flow from=20 0.5 - 1 Amp (for a very short duration). As far as affecting the 12 = Volt signal it would only draw 12/100 =3D 0.12 amp or 120 milliamps. = That would be pulled through the injectors at all times. The injector = resistance is probably (peak and hold case) around 3 ohms. So the = injector would draw 12/3 =3D 4 amps (DC case - its undoubtedly less due = to the A/C impedance of the coil). It make take some experimenting - = but 100 ohm looks like a good place to start. =20 The wattage should probably be around 5 - 10 watts just to be on the = safe side. =20 =20 So certainly looks like a suggestion that would work, Joe. =20 =20 =20 Ed ------=_NextPart_000_017B_01C76417.032043A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message=
Steve has a good handle on the factors involved here. 
 
 His RC snubber definitely addresses the root cause of the = problem=20 and works.   Note that this requires = removing or=20 disabling the diode clamps.
 
 My job now is to come up with a fix that accomplishes the = same thing=20 and is easy as possible to implement AND to verify that there are no = other=20 'gotchas'.   The first part was relatively easy.  It = involves=20 cutting one trace on the circuit board and adding a single = component=20 (resistor [or a MOV as Marv suggested])  in a position that is easy = to=20 retrofit.   Completed the bench and flight testing yesterday=20 with excellent results. 
 
The second part (checking for 'gotchas') was the hard = part. =20 A detailed report would take more time than I've got but here are the=20 basics. 
 
Compensating for the shorter (actual) injector open = times requires=20 that the EC2 increase the injector pulse widths.  The means to do = this are=20 already there in Mode 3 (injector flow rate adjustment).  It does = require a=20 big change (about 53% in my case with the Renesis saturated injectors) = in the=20 Mode 3 constant.   It was at 150 and had to be increased to = 230. =20 This alone was enough to get the engine mixture back in range and safe = to=20 fly.   I spent about 3 minutes on the ground coarse = tuning=20 the MAP table, then took off and let the EM2 autotune do the fine=20 tuning.   All went well until I got to the full throttle / = high speed=20 part of the test.  When the engine reached about 6000 rpm the = engine went=20 into rev-limit (ignition & fuel cut until revs dropped below limit = then=20 switches back on until rev limit reached again).  Very = disconcerting when=20 in-flight.  Engine ran fine when throttled back.  This was NOT = due to=20 the normal rev limiter function which is programmed at 7500 rpm.
 
Much geeky software debugging later I found that it was caused as a = side=20 effect of altering the IPW (injector pulse width) clock beyond it's = normal=20 range.  This clock is also used in another function which didn't = like=20 this.  This particular bug only affects the Renesis and other = single sensor=20 engines.   Very easy software fix once = it was found. =20 2nd & 3rd gen 13Bs and 20Bs use 2 sensors so are not affected by=20 this.   Still checking the dozen or so other engine types that = the EC2=20 is made for.
 
The final result on my engine (Renesis) did not show any = dramatic=20 change in engine performance or difference in idle smoothness.  As = Ed=20 noted, the small primary injectors (290 cc) make it more tolerant of the = pulse=20 stretching effect of the diode clamps.  I also got reasonably good = idle on=20 my 2nd gen 13B using 440 cc injectors.  The bigger they are, the = more=20 difficult they will be to tune and the more susceptible they will be to = idle=20 problems at low speed. 
 
On the plus side, there were fewer and smaller changes (from = nominal)=20 needed in the map table.  This made tuning easier and = faster.   I=20 will probably be able to idle slower but I will have to get under the = cowl and=20 adjust the stop on throttle body to try it.  It idles at 1600 rpm = very=20 smoothly (before & after the change).
 
Sudden power chops to idle when entering the pattern go=20 noticeably smoother now.  I was used to the occasional burble & = pop=20 similar to what you've probably heard from P-51s and other warbirds = in the=20 pattern at fly-ins.   
 
More details to follow.
 
Tracy
 
 
----- Original Message -----
To: Rotary motors in = aircraft
Sent: Sunday, March 11, 2007 = 2:21=20 PM
Subject: [FlyRotary] Re: A = solution? was=20 : The truth??? / Injector flow rate mystery solved

Ed and=20 Joe,

 

The diode = in the EC2=20 allows the current from the collapse of the injector magnetic field to = flow to=20 the positive supply rail (~14V); it doesn=92t oppose this.  A resistor allowing this = current to=20 flow would also result in a close delay since the current flowing is = what=20 maintains the magnetic field during this delay.   What is needed is a = way to=20 decrease the rate of voltage rise just after the EC2 pulse ends so = arcing in=20 the A/B selection relay is suppressed. =20 After the relay contacts open enough that an arc is no longer = possible=20 (which shouldn=92t take long) an open circuit condition now would = allow the=20 injector to close quickly.  = The=20 arcing may or may not be a problem any given time the relay is opened = since=20 the timing of the end of the EC2 pulse and the opening of the relay = are=20 independent and arbitrary.  =20 One possible solution is a RC snubber rather=20 than the resistor that Joe proposed.  I think=20 Tracy is working = on=20 checking this out.  I = have=20 installed this in my plane and it works. =20 Tracy, however = can do a=20 much more thorough job of evaluating this and be sure the change is=20 reliable.  Let=92s give = him a chance=20 to do this before we do something we wish we=20 hadn=92t.

 

Steve

  =20

 

-----Original=20 Message-----
From: = Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed = Anderson
Sent: Sunday, March 11,=20 2007 = 9:16=20 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] A = solution? was :=20 The truth??? / Injector flow rate mystery solved

 

Sounds like a=20 reasonable approach  to me Joe.   A pull-down = resistor=20 would be relatively easy  for me to install  - I have = the=20 resistor pack required for the peak-hold type injectors.  So I = could=20 easily place four additional resistors in that=20 box.

 

If I understand you = (please=20 correct me if I don't), the pull down resistor should go between the = injector=20 and the EC2 sinking terminals.  That way the current induced when = the=20 intended pulse terminates and the magnetic field collapses will have a = path to=20 ground rather than being opposed by the diode in the=20 Ec2.

 

The value of said = resistor could=20 be around 100 ohms.  Since the induced voltage could reach from = 50 - 100+=20 volts an 100 ohm resistor could flow from =

0.5 - 1 Amp (for a very = short=20 duration).  As far as affecting the 12 Volt signal it would only = draw=20 12/100 =3D 0.12 amp or 120 milliamps.  That would be pulled = through the=20 injectors at all times.  The injector resistance is = probably (peak=20 and hold case) around 3 ohms.  So the injector would draw 12/3 = =3D 4 amps=20 (DC case - its undoubtedly less due to the A/C impedance of the = coil). =20 It make take some experimenting - but 100 ohm looks like a good place = to=20 start.

 

The wattage should = probably be=20 around 5 - 10 watts just to be on the safe side. =20

 

So certainly looks like = a=20 suggestion that would work, Joe.  =

 

 

Ed

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