X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3888155 for flyrotary@lancaironline.net; Fri, 16 Oct 2009 10:06:43 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta01.mail.rr.com with ESMTP id <20091016140607180.JNHF3542@cdptpa-omta01.mail.rr.com> for ; Fri, 16 Oct 2009 14:06:07 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing power? Date: Fri, 16 Oct 2009 10:06:09 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01CA4E48.48E576D0" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcpOYCni3ZqjIg+rQDKrN+6kLZn7IgAB7aLQ In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20091016140607180.JNHF3542@cdptpa-omta01.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0012_01CA4E48.48E576D0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi Bill, I could be wrong, but, I'm fairly certain that the position of the Ec2 manual mixture control does not necessarily have any deterministic relationship to air/fuel ratio of the EC2. The resulting air/fuel ratio is a combination of (among other things) the MCT bin (pointed to by manifold pressure) in which the engine is operating plus the effect of the manual mixture control knob. The narrow band O2 sensor response curve is pretty crappy for any sort of linear interpolation - but, most have a range of from a few 10 millivolts to approx 1.1 volt. With the higher voltage 1.0 representing higher air/fuel ratios - somewhere in the vicinity of 12 - 10 :1 air/fuel ratio. Stioch (14.7:1) voltage is normally around 0.45 volts (or 450 millvolts) and that is generally the only value that is really rather accurate on a narrow band O2 sensor. So with my EFISM if the air/fuel ratio indictor is in the middle of its range on the display, it should be yellow in color. I also have a feature that when looking at the air/fuel indicator screen (the one with fuel flow and fuel used values displayed), if you press button b3 and b4 together you will get displayed in the air/fuel ratio window of the actual voltage being read from the O2 sensor. So if the EFISM indicator is yellow and in the middle the voltage should read somewhere close to 450 mv. IF it is green and near the right hand limit the voltage will probably be reading around 900 mv indicating an higher air/fuel ratio. If red and to the left side then it will be reading less than 450 mv. However, remember that the curve for the narrow band O2 sensor is not very suitable for interpolation. The wide band O2 sensor is much better and therefore you can get more accurate indication of air/fuel ratio. So almost all narrow band O2 air/fuel ratio indictors are only useful in giving you a relative indication of leaner or richer. In fact, I am considering a future modification/option/user selectable Narrow band or wide band O2 sensor for the EFISM. Initially the wide band O2 sensors were in the $250 -$300 range, but now have dropped down to around $80 for the borsch model which makes them more cost feasible. I probably did not answer your question, but that is as close as I could come. 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 _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry Sent: Friday, October 16, 2009 8:57 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing power? Good point, Ed. How much change does the mixture knob on the EC-2/3 allow? Say for instance, if Mike was at 14.7 at full throttle with the mixture knob at the center position, how far would he have to turn the knob to the right to achieve 12.65 AFR? I ask this because the A/F gage will not read that mixture. It will be topped out well before that mixture ratio occurs. How do you determine best power mixture? Bill B _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson Sent: Friday, October 16, 2009 8:35 AM To: Rotary motors in aircraft Subject: [FlyRotary] Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing power? Hi Mike, I guess I'm missing something - If your mixture monitor shows stoich at full throttle, then it's not solely an airflow problem - it appears to me that it's the lack of sufficient fuel. IF you are at stoich 14.7:1 A/F ratio then that means you have more oxygen available in your system to support burning more fuel = more power. You should be able to enrich the mixture particularly at full throttle (assuming you are wanting full power at full throttle) to around 12.65:1 air/fuel ratio for best power. I know you know all of this - that is why I am puzzled by your statement that you feel it's an airflow problem when on the surface with the Stoich ratio it would appear it's a lack of sufficient fuel. 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 _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills Sent: Thursday, October 15, 2009 11:22 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: where's the missing power? Sorry for my absence on a topic I started. My nephew had a skateboarding accident last weekend and is in the hospital in a chemically induced coma until his brain swelling is under control. And I thought car powered airplanes were dangerous. Stay away from skateboards. Tracy - My mixture monitor shows stoich at full throttle. I suspect an airflow issue rather than fuel. Al - my vacuum gauge is located in the plenum directly behind the throttle plates. Lynn - I agree that the TB inlet is horrible and needs a bell mouth. The inlet is also pretty obstructed by the cowl which isnt visible in the pics I sent. I think I'll make an attempt to clean this up some and see if it gets me anywhere. If not I'll live with it for a while. Kelly - always tough to determine if the problem is an engine issue or if the load is simply too much for the engine to overcome. I'm going to experiment with the shallow dive several have suggested and see what happens. Mike ----- Original Message ----- From: Bill Bradburry To: Rotary motors in aircraft Sent: Tuesday, October 13, 2009 4:21 PM Subject: [FlyRotary] Re: where's the missing power? Since you have the vacuum gauge, this article will help you use it for troubleshooting. http://autospeed.com/cms/A_2393/article.html Bill B _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen Sent: Tuesday, October 13, 2009 7:22 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: where's the missing power? I dont have a regular manifold pressure gauge, just an industrial type vacuum gauge ( I really gotta get an MP gauge). Anyway, the vacuum gauge was indicating 4" of vacuum. Where are you measuring the 4" vacuum? If it is near the ports it is no unusual; if it is out before the runners; something is wrong. Al __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_0012_01CA4E48.48E576D0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi = Bill,

 

I could be wrong, but, I’m = fairly certain that the position of the Ec2  manual mixture control does = not necessarily have any deterministic relationship to air/fuel ratio of the = EC2. The resulting air/fuel ratio is a combination of (among other things) the = MCT bin (pointed to by manifold pressure)  in which the engine is operating = plus the effect of the manual mixture control knob.  =

 

The narrow band O2 sensor response = curve is pretty crappy for any sort of linear interpolation – but, most = have a range of from a few 10 millivolts to approx 1.1 volt.  With the = higher voltage 1.0 representing higher air/fuel ratios – somewhere in the = vicinity of 12 – 10 :1 air/fuel ratio.  Stioch  (14.7:1) voltage = is normally around 0.45 volts (or 450 millvolts) and that is generally the = only value that is really rather accurate on a narrow band O2 sensor.  =

  =

So with my EFISM if the air/fuel = ratio indictor is in the middle of its range on the display, it should be = yellow in color.  I also have a feature that when looking at the air/fuel = indicator screen (the one with fuel flow and fuel used values displayed), if you = press button b3 and b4 together you will get displayed in the air/fuel ratio = window of the actual voltage being read from the O2 sensor.  So if the EFISM indicator is yellow and in the middle the voltage should read somewhere = close to  450 mv.  IF it is green and near the right hand limit the = voltage will probably be reading around 900 mv indicating an higher air/fuel ratio.  If red and to the left side then it will be reading less = than 450 mv. 

 

However, remember that the curve = for the narrow band O2 sensor is not very suitable for interpolation.  The = wide band O2 sensor is much better and therefore you can get more accurate indication of air/fuel ratio.

 

So almost all narrow band O2 = air/fuel ratio indictors are only useful in giving you a relative indication of = leaner or richer.

 

In fact, I am considering a future = modification/option/user selectable Narrow band or wide band O2 sensor for the EFISM.  = Initially the wide band O2 sensors were in the $250 -$300 range, but now have = dropped down to around $80 for the borsch model which makes them more cost = feasible.

 

I probably did not answer your = question, but that is as close as I could come.

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry
Sent: Friday, October 16, = 2009 8:57 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing = power?

 

Good point, Ed.

How much change does the mixture knob on the EC-2/3 allow?  = Say for instance, if Mike was at 14.7 at full throttle with the mixture knob = at the center position, how far would he have to turn the knob to the right to = achieve 12.65 AFR?  I ask this because the A/F gage will not read that mixture.  It will be topped out well before that mixture ratio occurs.  How do you determine best power = mixture?

Bill B

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Friday, October 16, = 2009 8:35 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] = Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing = power?

Hi = Mike,

 

I guess I’m missing something = - If your mixture monitor shows stoich at full throttle, then it’s not = solely an airflow problem – it appears to me that it’s the lack of sufficient fuel. IF you are at stoich 14.7:1 A/F ratio then that means = you have more oxygen available in your system to support burning more fuel =3D = more power.   You should be able to enrich the mixture particularly = at full throttle (assuming you are wanting full power at full throttle) to = around 12.65:1 air/fuel ratio for best power.  I know you know all of this = - that is why I am puzzled by your statement that you feel it’s an = airflow problem when on the surface with the Stoich ratio it would appear = it’s a lack of sufficient fuel. 

 

 

 

Ed.  =

 

From: = Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Mike = Wills
Sent: Thursday, October = 15, 2009 11:22 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = where's the missing power?

 

Sorry for my absence on a topic I started. My = nephew had a skateboarding accident last weekend and is in the hospital in a chemically induced coma until his brain swelling is under control. And I thought car powered airplanes were dangerous. Stay away from = skateboards.

 

Tracy - My mixture monitor shows stoich at full throttle. I suspect an airflow = issue rather than fuel.

 

Al - my vacuum gauge is located in the plenum = directly behind the throttle plates.

 

Lynn - I agree that the TB inlet is horrible and needs a bell mouth. The inlet is also = pretty obstructed by the cowl which isnt visible in the pics I sent. I think I'll make an = attempt to clean this up some and see if it gets me anywhere. If not I'll live = with it for a while.

 

Kelly - always tough to determine if the problem is = an engine issue or if the load is simply too much for the engine to = overcome. I'm going to experiment with the shallow dive several have suggested and see = what happens.

 

Mike

----- Original Message ----- =

Sent: = Tuesday, October 13, 2009 4:21 PM

Subject: = [FlyRotary] Re: where's the missing power?

 

Since you have the vacuum gauge, this article will help you use = it for troubleshooting.

 

 http://autospeed.co= m/cms/A_2393/article.html

 

Bill B

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen
Sent: Tuesday, October = 13, 2009 7:22 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = where's the missing power?

I dont have a regular = manifold pressure gauge, just an industrial type vacuum gauge ( I really gotta = get an MP gauge). Anyway, the vacuum gauge was indicating 4" of = vacuum.

 

Where are you measuring the = 4” vacuum?  If it is near the ports it is no unusual; if it is out = before the runners; something is wrong.

 

Al



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

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