X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 19 May 2011 16:45:31 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-banded.atl.sa.earthlink.net ([209.86.89.70] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4988806 for lml@lancaironline.net; Thu, 19 May 2011 14:26:19 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.70; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=q4o09tLT54ndg/xnMVLtmx4ODtoaJUYBU/s49N32d0tIToH+cZEJS8DPur7rMuLX; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.194] (helo=[192.168.1.131]) by elasmtp-banded.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1QN7ur-000628-UG for lml@lancaironline.net; Thu, 19 May 2011 14:25:46 -0400 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: multipart/alternative; boundary=Apple-Mail-328--1042652394 Subject: Re: [LML] Re: Fuel restriction or air? X-Original-Date: Thu, 19 May 2011 14:25:45 -0400 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1082) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940ea8bd0f5bdf710c989d245e3fd87ac28350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.194 --Apple-Mail-328--1042652394 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 That would be 1.4 miles per hour. Wonder what a naca vent that gets = the air to slow down smoothly from 250 mph down to 1.4 looks like? On May 19, 2011, at 11:11 AM, MikeEasley@aol.com wrote: > I had to drain a tank on a IV to repair a fuel leak. I plugged the = vent while I removed the drain valve from the bottom of the wing, with = the hope that it would slow the flow of fuel down my arm. I only got = about a half gallon from the tank until the flow slowed to a drip. I = don't think the engine driven pump or boost pump could overcome the = vacuum caused by a clogged vent line. So a clogged vent would stop the = engine I'm guessing, not cause it to surge. > =20 > I did the calculation one time to determine the air flow that has to = come in the vents to replace the fuel going into the engine. I have = 3/8" vent lines on my ES and that air is moving through that vent line a = couple feet per second if I remember correctly. > =20 > Mike Easley > Colorado Springs > =20 > In a message dated 5/18/2011 6:42:57 A.M. Mountain Daylight Time, = n5zq@verizon.net writes: > Good point, Bill. The check valves supplied by Lancair for the vent = system on my IV are free flowing inward and =93somewhat=94 restricted = flowing outward. This prevents venting a lot of fuel overboard while = taxiing with full wing tanks (no winglets) yet allows air to escape at a = relatively slow rate to avoid the problem that you describe. Certainly, = a normal one way valve (free flow one direction =96 no flow in the = other) should NOT be used on a vent system. > =20 > Bill Harrelson > N5ZQ 320 1,900 hrs > N6ZQ IV under construction > =20 > =20 > =20 > =20 > From: Bill Hannahan > Sent: Wednesday, May 18, 2011 7:43 AM > To: lml@lancaironline.net > Subject: [LML] Fuel restriction or air? > =20 > =20 > {Did you verify the fuel vents are working properly? ....and that = the check valves on the vents are oriented correctly?} > =20 > There should be no check valves on vent lines. If you take off at sea = level with a wing tank at atmospheric pressure, 14.7 psia trapped by a = check valve, and climb to 18,000 feet, static pressure 7.35 psia, the = differential pressure on the tank will be 7.35 psi, 1,058 pounds per = square foot trying to rip the skins off the spar and ribs. > =20 > Vent lines must be free flowing both directions. >=20 > =20 > Regards, > Bill Hannahan >=20 > wfhannahan@yahoo.com >=20 --Apple-Mail-328--1042652394 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 That = would be 1.4 miles per hour.   Wonder what a naca vent that gets = the air to slow down smoothly  from 250 mph down to 1.4 looks = like?

On May 19, 2011, at 11:11 AM, MikeEasley@aol.com = wrote:

I had to drain a tank on a IV to repair a fuel leak.  I = plugged the=20 vent while I removed the drain valve from the bottom of the wing, with = the hope=20 that it would slow the flow of fuel down my arm.  I only got about = a half=20 gallon from the tank until the flow slowed to a drip.  I don't = think the=20 engine driven pump or boost pump could overcome the vacuum caused by a = clogged=20 vent line.  So a clogged vent would stop the engine I'm guessing, = not cause=20 it to surge.
 
I did the calculation one time to determine the air flow that has = to come=20 in the vents to replace the fuel going into the engine.  I have = 3/8" vent=20 lines on my ES and that air is moving through that vent line a = couple feet=20 per second if I remember correctly.
 
Mike Easley
Colorado Springs
 
In a message dated 5/18/2011 6:42:57 A.M. Mountain Daylight Time,=20= n5zq@verizon.net writes:
Good point, Bill. The check valves supplied by Lancair for the = vent=20 system on my IV are free flowing inward and =93somewhat=94 restricted = flowing=20 outward. This prevents venting a lot of fuel overboard while taxiing = with full=20 wing tanks (no winglets) yet allows air to escape at a relatively slow = rate to=20 avoid the problem that you describe. Certainly, a normal one way valve = (free=20 flow one direction =96 no flow in the other) should NOT be used on a = vent=20 system.
 
Bill Harrelson
N5ZQ 320 1,900 hrs
N6ZQ  IV under construction
 
 
 
 
Sent: Wednesday, May 18, 2011 7:43 AM
Subject: [LML] Fuel restriction or air?
 

= --Apple-Mail-328--1042652394--
=20 =20

 

{Did you verify the fuel vents are working=20 properly?   ....and that the check valves on the vents = are=20 oriented correctly?}

 

There = should be no check valves on vent lines. If you=20 take off at sea level with a wing tank at atmospheric pressure, = 14.7=20 psia trapped by a check valve, and climb to 18,000 feet, static = pressure=20 7.35 psia, the differential pressure on the tank will be 7.35 = psi, 1,058=20 pounds per square foot trying to rip the skins off the spar and=20= ribs.

 

Vent lines must be free flowing both=20 directions.


 

Regards,
Bill Hannahan