X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao102.cox.net ([68.230.241.44] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2240711 for flyrotary@lancaironline.net; Fri, 03 Aug 2007 15:49:06 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.44; envelope-from=alventures@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao102.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070803194826.BXPV7193.fed1rmmtao102.cox.net@fed1rmimpo02.cox.net> for ; Fri, 3 Aug 2007 15:48:26 -0400 Received: from BigAl ([72.192.132.90]) by fed1rmimpo02.cox.net with bizsmtp id XXoT1X00B1xAn3c0000000; Fri, 03 Aug 2007 15:48:27 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: Tips on tuning Date: Fri, 3 Aug 2007 12:50:37 -0800 Message-ID: <000001c7d60f$f1d944f0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7D5CC.E3B84EE0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7D5CC.E3B84EE0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Chris/David; =20 . In our=20 installation the primary fuel injectors are in the 500 cc range, where=20 the secondaries are in the 1500 cc range =20 Do you really mean 1500 cc/min? That's huge. It could make tuning a bit difficult. =20 Here are some suggestions for getting mixture tuned based on my = experience of re-tuning about 15 times, or more (remember the settings corruption problem I used to have?): =20 Get your coolant temp readout working. =20 Set mixture correction table to default (all zeros) if not already = there. Read the manual again; modes 3, 6, and 9. Also read again the EM2 = manual about 'Mixture Display' and 'Editing the MAP Table'.=20 =20 Normally one would first set Mode 3, but if your secondary are really = that large, you may wish to go to mode 6 first, turn the Program knob toward = the left, and push the store button a couple of times. =20 Go to Mode 3 at about 22" MAP. Adjust until the mixture monitor (MM) is about mid range (or oscillating, which it will do around stochiometric) = with the mixture knob at 12:00 oclock. =20 Then go back to Mode 6 and adjust until the mixture is fairly constant = above and below the stage point. =20 You could then get a first pass with Mode 1, but I have found it = sometimes simpler to just go to Mode 9; advance the throttle about 0.5" to 1" MAP = at a time, turn the Program knob to either about 9:00 (if you need to go = leaner) or 3:00 (if you need to go richer) and press the Store button as many = times as you need to get the MM about mid range. At MAP below about 12-13" = you'll want it richer, so set for the MM to be at or near the top. Continue up until maybe about 22". Make sure you keep a stable MAP as you make the adjustment. You can cut the running time by taking bigger steps in MAP = as you go you, because the idea is to edit the in-between entries from the = EM2 with the engine off. =20 Then, with engine off, display the mixture correction table on the EM2 = and edit the bars that look out of line to get a reasonable smooth = variation. Look at the trend of the bars approaching 22" MAP and continue the trend = up (probably up) gradually flattening out up toward 29 -30. If the values = are going to max or min of the range, you'll have to re-set mode 3 to shift = the distribution up or down. =20 Now you are ready to go to auto-tune. I have found that auto-tune (with mixture knob at 12:00) makes it too lean for best idle; so I usually = start the auto-tune at about 12.5 - 13" MAP.=20 =20 I would think an ideal IDLE power setting would=20 be where the plane does not require braking to remain still. =20 I have found that with my 66" dia - 80" pitch prop my Velocity doesn't = move until engine rpm is somewhere upward of 1500 rpm. =20 I get about 5500 static with my 20B, and about 5600 on takeoff. With adjustable pitch you will want to get some higher numbers. =20 Hope you find this helpful, =20 Al =20 ------=_NextPart_000_0001_01C7D5CC.E3B84EE0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Chris/David;

 

. In our

installation the primary fuel injectors are in the 500 cc range, where =

the secondaries are in the 1500 cc range

 

Do you really = mean 1500 cc/min?  That’s huge. It could make tuning a bit = difficult.

 

Here are some suggestions for getting mixture tuned based on my experience of = re-tuning about 15 times, or more (remember the settings corruption problem I used to = have?):

 

Get your = coolant temp readout working.

 

Set mixture = correction table to default (all zeros) if not already there. Read the manual = again; modes 3, 6, and 9.  Also read again the EM2 manual about ‘Mixture = Display’ and ‘Editing the MAP Table’.

 

Normally one = would first set Mode 3, but if your secondary are really that large, you may = wish to go to mode 6 first, turn the Program knob toward the left, and push the = store button a couple of times.

 

Go to Mode 3 = at about 22” MAP. Adjust until the mixture monitor (MM) is about mid range = (or oscillating, which it will do around stochiometric) with the mixture = knob at 12:00 oclock.

 

Then go back = to Mode 6 and adjust until the mixture is fairly constant above and below the = stage point.

 

You could then = get a first pass with Mode 1, but I have found it sometimes simpler to just go to = Mode 9; advance the throttle about 0.5” to 1” MAP at a time, turn = the Program knob to either about 9:00 (if you need to go leaner) or 3:00 (if = you need to go richer) and press the Store button as many times as you need = to get the MM about mid range. At MAP below about 12-13” you’ll = want it richer, so set for the MM to be at or near the top. Continue up until = maybe about 22”. Make sure you keep a stable MAP as you make the = adjustment. You can cut the running time by taking bigger steps in MAP as you go = you, because the idea is to edit the in-between entries from the EM2 with the = engine off.

 

Then, with = engine off, display the mixture correction table on the EM2 and edit the bars that look out = of line to get a reasonable smooth variation.  Look at the trend of the = bars approaching 22” MAP and continue the trend up (probably up) gradually = flattening out up toward 29 -30.  If the values are going to max or min of the = range, you’ll have to re-set mode 3 to shift the distribution up or = down.

 

Now you are = ready to go to auto-tune.  I have found that auto-tune (with mixture knob at = 12:00) makes it too lean for best idle; so I usually start the auto-tune at about 12.5 = – 13” MAP.

 

I would think an ideal IDLE power setting would

be where the plane does not require braking to remain = still.

 

I have found = that with my 66” dia – 80” pitch prop my Velocity doesn’t move until engine rpm is somewhere upward of 1500 rpm.

 

I get about = 5500 static with my 20B, and about 5600 on takeoff.  With adjustable pitch you = will want to get some higher numbers.

 

Hope you find = this helpful,

 

Al

 

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