Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3136761 for flyrotary@lancaironline.net; Tue, 30 Mar 2004 11:51:21 -0500 Received: from edward (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i2UGpIkG001868 for ; Tue, 30 Mar 2004 11:51:19 -0500 (EST) Message-ID: <002101c41677$39a88040$2402a8c0@edward> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: No rev-2 flying yet (Tracy, see comments in red) Date: Tue, 30 Mar 2004 11:51:19 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C4164D.509213E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C4164D.509213E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message Message -----=20 From: David Leonard=20 To: Rotary motors in aircraft=20 Sent: Tuesday, March 30, 2004 10:51 AM Subject: [FlyRotary] Re: No rev-2 flying yet (Tracy, see comments in = red) Rusty, that is exactly what I am experiencing. Always runs great = above 2000, can sometimes get it to behave down to 900 RPM and a MAP of = about 11, especially if I go slowly. But usually it gets stuck in that = too-rich-to-run-well-but-can't-tolerate-sudden-leaning-without-stopping = realm. David Leonard The Rotary Roster: http://members.aol.com/_ht_a/rotaryroster/index.html The other issue is when you chop the throttle from a high setting, to = idle. This is very strange. Say the idle is set at 1900 rpm, and I'm = running at high throttle. When I chop the throttle, the rpm goes low, = to around 1600 and stays there. During this time, the MP is 16.0, and = the engine is very rough. It will stay here forever, but if you turn = the mixture knob about 90 degrees CCW to lean it out, it smoothes out, = the rpm increases to 1900, and the MP drops to 13.0. If you are at a = higher throttle setting, and decrease throttle more slowly, it will come = down to 1900 rpm, 13 MP, and smooth. It also seems like the engine is = jumping back and forth between the dual map ranges, and I believe this = false 16" MP reading at the rough, low idle is from the dual map. I = think I even proved that to myself by watching the EM-2 screen that = shows EC-2 readings. I've got some work to do on this one, but it's = just a tuning issue. =20 Just to chime in, "Me Too!". I have noticed the same sort of = phenomena.=20 My guess is that it appears that when closing the throttle very = rapidly, you probably end up with an overly rich intake manifold = air/fuel mixture. This may occur because in one fraction of a second = you are opearting at WOT (lots of fuel flow) and the next down to = idle. So the rpm drops down in to the LOW, LOW range due to the rapid = decrease in manifold pressure caused by the rapid throttle closure and = still rapidly pumping rotors. So its down in the low rpm range with a = rich mixture and then since the rpm is so low, the manifold pressure = may well creeep back up to the 16-17" Hg range simple because there is = not enough rpm to keep the manifold pressure lower. So now the system = is seeing higher manifold pressure. Since the system only really uses = the manifold pressure (and not rpm) in its calculation, the higher = manifold pressure convinces itself that you have opened the throttle a = bit (while you actually have not) and so it dumps in a bit more fuel. = This keeps the mixture overly rich as there is really not as much air = coming into the system. Once you crack the throttle a bit, more air = flow leans out the mixture, rpm increases, manifold pressure actually = decrease back to 14-15" Hg and the system stabilizes. Recall this is a pressure density system and not an Airflow system, = so it only knows (or cares) about the manifold pressure (and in the = case of the A controller, your inlet air temp) and knows nothing about = your throttle setting or airflow or even rpm except as inferred by = manifold pressure. Rpm is "automatically" taken care of by the fact the = faster the rpm the more often the injectors are triggered per unit time, = but rpm is not a direct computational factor in determining fuel, only = manifold pressure (and air temp in case of controller A) My 0.02=20 Ed Anderson. ------=_NextPart_000_001E_01C4164D.509213E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 Message -----
From:=20 David=20 Leonard
Sent: Tuesday, March 30, 2004 = 10:51=20 AM
Subject: [FlyRotary] Re: No = rev-2 flying=20 yet (Tracy, see comments in red)

Rusty, that = is=20 exactly what I am experiencing.  Always runs great above 2000, = can=20 sometimes get it to behave down to 900 RPM and a MAP of about 11, = especially=20 if I go slowly.   But usually it gets stuck in that=20 = too-rich-to-run-well-but-can=92t-tolerate-sudden-leaning-without-stopping= =20 realm.

 

David=20 Leonard

The Rotary=20 Roster:

http://memb= ers.aol.com/_ht_a/rotaryroster/index.html

 

The other issue is when you chop = the=20 throttle from a high setting, to idle.  This is very = strange.  Say=20 the idle is set at 1900 rpm, and I=92m running at high throttle.  = When I=20 chop the throttle, the rpm goes low, to around 1600 and stays=20 there.  During this time, the MP is 16.0, and the engine is very=20 rough.  It will stay here forever, but if you turn the mixture = knob about=20 90 degrees CCW to lean it out, it smoothes out, the rpm increases to = 1900, and=20 the MP drops to 13.0.  If you are at a higher throttle setting, = and=20 decrease throttle more slowly, it will come down to 1900 rpm, 13 MP, = and=20 smooth.  It also seems like the engine is jumping back and forth = between=20 the dual map ranges, and I believe this false 16" MP reading at the = rough, low=20 idle is from the dual map.  I think I even proved that to = myself by=20 watching the EM-2 screen that shows EC-2 readings.   I=92ve = got some=20 work to do on this one, but it's just a tuning issue.  =

 

Just to chime in, "Me Too!".  I = have noticed=20 the same sort of phenomena. 

 

My guess is that it  appears that when = closing=20 the throttle very rapidly, you probably end up with an overly =  rich=20 intake manifold air/fuel mixture.  This may occur because in = one=20 fraction of a second you are  opearting at WOT (lots of fuel = flow)=20  and the next down to idle.  So the rpm drops down in to the = LOW,=20 LOW range due to the rapid decrease in manifold pressure caused by the = rapid=20 throttle closure and still rapidly pumping rotors.  So its = down in=20 the low rpm range with a rich mixture and then since the rpm is so = low, =20 the manifold pressure may well creeep back up to the 16-17" Hg range = simple=20 because there is  not enough rpm to keep the manifold = pressure=20 lower.  So now the system is seeing   higher manifold=20 pressure.  Since the system only really uses the manifold = pressure (and=20 not rpm) in its calculation, the higher manifold pressure convinces = itself=20 that  you have opened the throttle a bit (while you actually = have=20 not) and so it dumps in a bit more fuel. This keeps the mixture = overly=20 rich as there is really not as much air coming into the = system. =20 Once you crack the throttle a bit, more air flow leans out the = mixture, rpm=20 increases, manifold pressure actually decrease back to 14-15" Hg and = the=20 system stabilizes.

 

  Recall this is a pressure density = system and=20 not an Airflow system, so it only knows (or cares) about  the = manifold=20 pressure (and in the case of the A controller, your inlet air temp) = and knows=20 nothing about your throttle setting or airflow or even rpm except as = inferred=20 by manifold pressure.  Rpm is "automatically" taken care of by = the fact=20 the faster the rpm the more often the injectors are triggered per unit = time,=20 but rpm is not a direct computational factor in determining fuel, only = manifold pressure (and air temp in case of controller = A)

 

My 0.02

 

Ed Anderson.

 

 

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