X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost04.isp.att.net ([207.115.11.54] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3746773 for flyrotary@lancaironline.net; Mon, 06 Jul 2009 14:40:25 -0400 Received-SPF: pass receiver=logan.com; client-ip=207.115.11.54; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-230-69-48.mco.bellsouth.net[74.230.69.48]) by isp.att.net (frfwmhc04) with SMTP id <20090706183946H0400eu3tge>; Mon, 6 Jul 2009 18:39:46 +0000 X-Originating-IP: [74.230.69.48] From: "Bill Bradburry" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Potential Low range MCT (MAP) Problem on EC3/Ec2 Date: Mon, 6 Jul 2009 14:39:48 -0400 Message-ID: <82A4C11C1738448793D1B22EDA94F2BB@Desktop> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01C9FE47.9D40E9E0" X-Mailer: Microsoft Office Outlook 11 Thread-Index: Acn+RZkBShzpYyy0TZ2Q3BxoN+GTogAIL4Jw X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_0012_01C9FE47.9D40E9E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ed, That was mentioned before by someone (Tracy?). They said that is why = the addresses above and below 31 that have the same manifold pressure should = be the same or very close. The EC-2 could begin to =93hunt=94 moving back = and forth between the upper and lower addresses and if they were not close = to the same, there would be a problem. Also, reading both Steven and Bob on the injector disable=85 I don=92t = think either of them is correct. I think Tracy said or implied that if you = shut down the primaries, the EC-2 would turn on the secondaries, period. Not = to do this would mean that you would be a fool to try it if you were = staging because the engine would shut down. You also do not have to turn on the cold start switch because that is done automatically when you flip the disable switch. If you are staging, the cold start switch should have = no effect because you are just looking for 2 injectors. If you have = different size injectors, you would have to mess with the mixture. Above staging, = the cold start would be effective, but you would still have to mess with the mixture if you have different size injectors. I sounds like Steven is actually doing this with his engine and = reporting what happens. If that is true, then theory be dammed, we are staring at facts unless he used a different wiring scheme. =20 When will Tracy be back to tell us what really should happen. You cant = make proper decisions about operating the engine if you don=92t know what it = is supposed to do under certain circumstances. Bill B=20 =20 _____ =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson Sent: Monday, July 06, 2009 10:25 AM To: Rotary motors in aircraft Subject: [FlyRotary] Potential Low range MCT (MAP) Problem on EC3/Ec2 I happened to be reading the EC3 operating manual =96 doesn=92t everyone = do this for pleasure reading{:>)? When I came across something that may explain something that Joe and I observed (and may have played a role in the = hard to start problem we initially encountered (after the CAS wiring problem was fixed) =20 Joe has the later version of the EC2 where the lower rpm operating of = the fuel MAP (or more correctly the MCT - Map Correction Table), where the common assumption/understanding is that the operating point below 2300 = rpm is based solely on rpm. Turn=92s out that assumption is not quite = correct per this extract from the EC3 manual. =20 EC3 Mixture Correction Table addressing is illustrated on the = following page. Note that below 2300 rpm and 13=94 manifold pressure (absolute), = the MCT address is a function of rpm as opposed to manifold pressure. If = you have an EM2 engine monitor to display the data, you can use a copy of = this chart to record your table data after the engine is tuned =20 =20 Not that there are two conditions that must be met before the EC3/EC2 = uses only rpm to determine the lower operating point. The engine rpm must be below 2300 AND the manifold pressure must be below 13=94 Hg. So that = implies that if you are operating at 2000 rpm, but your manifold pressure is at = 13.5 or 14 or higher then the EC2 is using the manifold pressure to determine = the operating point and not the rpm. =20 So lets say you are trying to start your engine =96 rpm < 2300 but = manifold pressure > 13. Therefore the MCT pointer may be pointing to the bin corresponding to a manifold pressure that is close to ambient (29.92=94 = Hg). That is also the point for WOT throttle (Lots of fuel). So its safe to = say that on the first turn of the prop that is where your Ec3/2 is at. The instance the engine fires, the manifold pressure immediately begins to = drop =96 how fast it drops will depend in part on what throttle setting you = have. If you throttle is closed, the manifold pressure will almost immediately drop to low values (presumably below 13=94 hg) and all is well. If = however, your throttle is set at =BC or more open, then the manifold pressure is = not as likely to drop below 13=94 hg. If this is the case, then the operating = point is going to be based on manifold pressure which may be considerably = above 13=94 Hg. That point in turn may be overly rich for idle conditions and = your engine fails to sustain operation do to excess fuel and floods. =20 Tracy, of course, may have algorithms to deal with this, but based = solely on the comments in the manual =96 looks like this could happen. = Particularly in the early stages, before you get the MCT tuned. =20 Thought I would pass this on =96 my older EC2 only uses manifold = pressure across the entire range. =20 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 http://www.rotaryaviation.com/Rotorhead%20Truth.htm =20 =20 ------=_NextPart_000_0012_01C9FE47.9D40E9E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Ed,

That was mentioned before by someone (Tracy?).=A0 They said that = is why the addresses above and below 31 that have the same manifold pressure = should be the same or very close.=A0 The EC-2 could begin to “hunt” = moving back and forth between the upper and lower addresses and if they were not = close to the same, there would be a problem.

Also, reading both Steven and Bob on the injector disable… = I don’t think either of them is correct.=A0 I think Tracy said or implied that if you shut down the primaries, the EC-2 would turn = on the secondaries, period.=A0 Not to do this would mean that you would be a = fool to try it if you were staging because the engine would shut down.=A0 You also = do not have to turn on the cold start switch because that is done automatically = when you flip the disable switch.=A0 If you are staging, the cold start switch = should have no effect because you are just looking for 2 injectors.=A0 If you have = different size injectors, you would have to mess with the mixture.=A0 Above = staging, the cold start would be effective, but you would still have to mess with the mixture if you have different size = injectors.

I sounds like Steven is actually doing this with his engine and reporting what happens.=A0 If that is true, then theory be dammed, we = are staring at facts unless he used a different wiring scheme.=A0 =

When will Tracy be back to tell us what really should happen.=A0 You cant make proper = decisions about operating the engine if you don’t know what it is supposed = to do under certain circumstances.

Bill B 

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Monday, July 06, = 2009 10:25 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] = Potential Low range MCT (MAP) Problem on EC3/Ec2

I happened to be reading the EC3 operating manual = – doesn’t everyone do this for pleasure reading{:>)? When I came = across something that may explain something that Joe and I observed (and may = have played a role in the hard to start problem we initially encountered = (after the CAS wiring problem was fixed)

 

Joe has the later version of the EC2 where the lower = rpm operating of the fuel MAP  (or more correctly the MCT - Map = Correction Table), where the common assumption/understanding  is that the = operating point below 2300 rpm is based = solely on rpm.  Turn’s out that assumption  is not quite correct per this = extract from the EC3 manual.

 

EC3  Mixture Correction Table addressing  is illustrated on the following page.  = Note that below 2300 rpm and 13” manifold pressure (absolute), the MCT address is = a function of rpm as opposed to manifold pressure.   If you have an EM2 = engine monitor to display the data, you can use a copy of this chart to record = your table data after the engine is tuned

 

 

Not that there are two conditions that must be met = before the EC3/EC2 uses only rpm to determine the lower operating point.  = The engine rpm must be below 2300 AND the manifold pressure must be below = 13” Hg.  So that implies that if you are operating at 2000 rpm, but = your manifold pressure is at 13.5 or 14 or higher then the EC2 is using the = manifold pressure to determine the operating point and not the = rpm.

 

So lets say you are trying to start your engine = – rpm < 2300 but manifold pressure > 13.  Therefore the MCT pointer = may be pointing to the bin corresponding to a manifold pressure that is close = to ambient (29.92” Hg).  That is also the point for WOT throttle = (Lots of fuel).  So its safe to say that on the first turn of the prop = that is where your Ec3/2 is at.  The instance the engine fires, the = manifold pressure immediately begins to drop – how fast it drops will = depend in part on what throttle setting you have.  If you throttle is closed, = the manifold pressure will almost immediately drop to low values (presumably = below 13” hg) and all is well.  If however, your throttle is set at = =BC or more open, then the manifold pressure is not as likely to drop below = 13” hg.  If this is the case, then the operating point is going to be = based on manifold pressure which may be considerably above 13” Hg.  = That point in turn may be overly rich for idle conditions and your engine = fails to sustain operation do to excess fuel and = floods.

 

Tracy, of course, may have algorithms to deal with this, but based solely on the comments = in the manual – looks like this could happen.  Particularly in the = early stages, before you get the MCT tuned.

 

Thought I would pass  this on – my older = EC2 only uses manifold pressure across the entire = range.

 

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

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

 

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