X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from outbound-mail.dca.untd.com ([64.136.47.15] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with SMTP id 5112049 for flyrotary@lancaironline.net; Fri, 02 Sep 2011 14:06:16 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.47.15; envelope-from=alwick@juno.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juno.com; s=alpha; t=1314986740; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; l=0; h=Message-ID:From:To:Subject:Date:Content-Type; b=jmJxD5FNF3VIfQDVsHdoJWx7E1O086DnA0kSRqZjg9FA6pZ0cbIvRaWisjAyYArQP 0yFKo0QNrd3lOpknXUnFvsbBTLp7SPAtXFdme+MYxaoymAVL9f90XbwcQVYFS2K3dQ QEGx0j2KeTmfrpi/2uIEDNsDFg9+NuoKh2ytb+kQ= Received: from Penny (50-39-162-158.bvtn.or.frontiernet.net [50.39.162.158]) by smtpout06.dca.untd.com with SMTP id AABHGCGYNAACBQZJ for (sender ); Fri, 2 Sep 2011 11:05:00 -0700 (PDT) Message-ID: <9E4A3790D37C40279B0F388705E2E0F9@Penny> From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] vapor lock Date: Fri, 2 Sep 2011 11:04:58 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01B3_01CC6960.276689B0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 X-UNTD-BodySize: 8049 X-ContentStamp: 19:9:2935678080 X-MAIL-INFO:0d13beabbeabdaafabdfdad3dfda9a473fcf373a433b7e373fbb3ebbf7c33b07bbda17ea8eea8e6e1e8e276ea3276eeb07db2adf3aebfad38adf1a4af393935b734fcb2feac38e8fc7ea27eeee4bc7ae7f7acefe1efe232b8afa9e6f6e477a03e79a4e3efbbfaf47472e3fa31e0abf4bef9bbacf8fcf9f0b5a3e372efb3fbe7e7e077713ef17f7bbda X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkJUj+RXqxSjQ1nTlnf3JXYvRfOKnlzKI9w== X-UNTD-Peer-Info: 10.171.42.36|smtpout06.dca.untd.com|smtpout06.dca.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_01B3_01CC6960.276689B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable What fine work Steve. I love it when someone converts theory to facts. = You measured that all at sea level. Now just subtract 5.35 from all your = pressure numbers if you fly at 12k ft. You've now measured all of the = variables that affect vapor lock. Only remaining item is measuring = pressure at your pump inlet. You then can predict exactly how safe your = plane is without ever flying! How cool is that? I use a submerged fuel pump for added safety. Two actually. Easy to = maintain, just remove the 6 screws that hold the pumps in place. So = there is zero significance to the argument of maintenance. Can't imagine = how anyone could claim maintenance is more important than life risk = anyway. I return all fuel to my 3 gallon sump. Vent can go anywhere, you = don't have to tie vent into main fuel vents.=20 Once again, nice work Steve.=20 -al wick ----- Original Message -----=20 From: Steven W. Boese=20 To: Rotary motors in aircraft=20 Sent: Friday, September 02, 2011 12:04 AM Subject: [FlyRotary] vapor lock For those concerned about the formation of vapor in a pressurized fuel = rail, I've attached a plot of data collected from local samples of 100 = LL avgas, 87 octane auto fuel with no ethanol, 91 octane auto fuel with = 10% ethanol, and tap water. The water was measured just as a check on = the method. The data would be considered more of a true vapor pressure rather than = a Reid vapor pressure due to the method used. The data indicates to me that if the fuel pressure in the fuel rail is = 35 psi as measured with a regular gauge referenced to the atmosphere at = sea level, the temperature of 100 LL or 91 octane 10% ethanol in the = rail would have to be in the neighborhood of 240 deg F for it to form = bubbles of vapor (boil). The sample of 87 octane would require a = temperature of about 215 deg F to form a vapor phase. My take on this is it may be more productive to be concerned about the = fuel supply to the high pressure pumps rather than worrying about "vapor = lock" downstream of those pumps. This seems to be the conclusion = reached by the recent thread on this subject, possibly now supported by = actual data. Of course the data only applies to the samples I obtained. The higher temperature tolerance of the auto fuel with ethanol = compared to the auto fuel without ethanol was surprising to me. But I only collect data --- it is up to an engineer to make sense of = it ;>) Steve Boese RV6A, 1986 13B NA, RD1A, EC2 -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_01B3_01CC6960.276689B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
What fine work Steve. I love it when = someone=20 converts theory to facts. You measured that all at sea level. Now just = subtract=20 5.35 from all your pressure numbers if you fly at 12k ft. You've now = measured=20 all of the variables that affect vapor lock. Only remaining item is = measuring=20 pressure at your pump inlet. You then can predict exactly how safe your = plane is=20 without ever flying! How cool is that?
 
I use a submerged fuel pump for added = safety. Two=20 actually. Easy to maintain, just remove the 6 screws that hold the pumps = in=20 place. So there is zero significance to the argument of maintenance. = Can't=20 imagine how anyone could claim maintenance is more important than life = risk=20 anyway. I return all fuel to my 3 gallon sump. Vent can go anywhere, you = don't=20 have to tie vent into main fuel vents.
 
Once again, nice work Steve. =
 
-al wick
 
 
----- Original Message -----
From:=20 Steven W. = Boese=20
Sent: Friday, September 02, = 2011 12:04=20 AM
Subject: [FlyRotary] vapor = lock

For those concerned about the formation of vapor in = a=20 pressurized fuel rail, I've attached a plot of data collected from = local=20 samples of 100 LL avgas, 87 octane auto fuel with no ethanol, 91 = octane auto=20 fuel with 10% ethanol, and tap water.  The water was measured = just as a=20 check on the method.

 

The data would be considered more of a true vapor = pressure=20 rather than a Reid vapor pressure due to the method = used.

 

The data indicates to me that if the fuel pressure = in the fuel=20 rail is 35 psi as measured with a regular gauge referenced to the = atmosphere=20 at sea level, the temperature of 100 LL or 91 octane 10% = ethanol in=20 the rail would have to be in the neighborhood of 240 deg F for it = to form=20 bubbles of vapor (boil).  The sample of 87 octane would = require a=20 temperature of about 215 deg F to form a vapor phase.

 

My take on this is it may be more productive to be = concerned=20 about the fuel supply to the high pressure pumps rather than worrying=20 about "vapor lock" downstream of those pumps.  This = seems to be=20 the conclusion reached by the recent thread on this subject, possibly = now=20 supported by actual data.  Of course the data only applies to the = samples=20 I obtained.

 

The higher temperature tolerance of the auto fuel = with ethanol=20 compared to the auto fuel without ethanol was surprising to = me.

 

But I only collect data --- it is up to an engineer = to make=20 sense of it ;>)

 

Steve Boese
RV6A, 1986 13B NA, RD1A,=20 EC2

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Homepage:  http://www.flyrotary.com/
Archive and=20 UnSub:  =20 = http://mail.lancaironline.net:81/lists/flyrotary/List.html
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