X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from outbound-mail.vgs.untd.com ([64.136.55.15] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with SMTP id 5095256 for flyrotary@lancaironline.net; Wed, 17 Aug 2011 13:08:00 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.55.15; envelope-from=alwick@juno.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juno.com; s=alpha; t=1313600845; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; l=0; h=Message-ID:From:To:Subject:Date:Content-Type; b=daIgpbmry4kgTCVTObycWfD49eoQPf5oHkWbVcE+kLmf1GuQNWPvWqXf0bR8TVo9n CuRcfOeO/E9MziBGFAkb6AJ0dU2KXNZTTR8/Adtjn2YSE+J0S+G3GS1Dfq53VkBwPq UioM4OwPGzXaXpFgfLvUDmEJ2+W001s2Hm/FIS2E= Received: from Penny (50-39-174-23.bvtn.or.frontiernet.net [50.39.174.23]) by smtpout02.vgs.untd.com with SMTP id AABHEZ7KPACLH5MA for (sender ); Wed, 17 Aug 2011 10:06:53 -0700 (PDT) Message-ID: <9CDEC018AA3C4681AEA92242C494CC5F@Penny> From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Dennis Haverlah Fuel System...or any others, for that matter. Date: Wed, 17 Aug 2011 10:06:51 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0196_01CC5CC5.62322D30" 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: 13810 X-ContentStamp: 34:17:1502297540 X-MAIL-INFO:0435cd9dcd7528b9759d5cbc9dad95f5d52ce139d1001d3d392c580158b9f81d8558f559c1e8c1e85d68e81c5d891c5d8c855c31add18c959dd9ad28dd8848486198c9dc19c1f8e86591c11c0909299115ccaca1ec68ecfc08d9956955fc7dac5545e5ec187879ec19457ce50100b8c569b1210c582ca5812d8131e8e18d99411db875eded353db958f19dcdd19829218505b928d95c9861dd5c5901f571c1d588d9f1 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkJy51UuSE81KcrUPwk93ZNFwmDhTB5kDSw== X-UNTD-Peer-Info: 10.181.42.32|smtpout02.vgs.untd.com|smtpout02.vgs.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_0196_01CC5CC5.62322D30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable wrote: Al Wick wrote: I'm really concerned for some of these fuel designs. The fuel = bleed has nothing to do with vapor lock. Virtually no effect at all. =20 I don't know why others are doing it, but for me, the bleed has = nothing at all to do with vapor lock. Some conversations have been = mixed together, so I can see how that could be the impression. The = point of the pressure bleed is to bleed off the pressure after shutdown. I have a strong, positive head pressure going into my pumps. They, = and the regulator, are about 8" directly below the tank. Excess fuel = goes back to the opposite side of the tank from the pickup, and a single = line goes forward to feed the injectors. The fuel lines are arranged = such that heat soaking the lines to the point of boiling the gas will = push liquid fuel down hill and behind the firewall, isolating the = gaseous gas with its heat at the top of the line. Turning the pumps on = will pressurize the line to 55psi, returning most of the gaseous fuel = back to a liquid state. The ECM is programmed for a longer clearing = pulse on hot start. The point of the bleed is to allow fuel to move back to the tank. I = had the issue of a the pressurized lines being perfectly sealed. The = pressurized fuel was finding the path of least resistance out, which = just happened to be out the injector and into the intake manifold where = it sat as a little puddle. Heat soaking the lines would not push liquid = fuel downhill and back behind the firewall. It would push more fuel = into the manifold. A puddle of gas sitting in a composite manifold, = just above a hot exhaust stack is just bad mojo. A poorly sealed = regulator allows the pressure to bleed off in about 5 seconds (give or = take), isolating the hot fuel in front of the firewall, and keeping the = rest cool and out of the intake manifold. Got nuthin' to do with vapor lock. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0196_01CC5CC5.62322D30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
<I would think that a well-designed fuel system with the pumps = located=20 as low as possible
 
Instead of speculations, you can = actually measure=20 how good it is. A pump, clear fuel lines, and water instead of fuel. = Pinch fuel=20 line with pliers to increase pressure drop.  Watch bubbles come out = of=20 solution. Hear the rattle from pump due to it's inability to flow air.=20
If you also put a pressure gage on pump = inlet, you=20 can see how fine fuel filter increases risk. You can see how small = diameter=20 tubing increases risk, heat, head pressure, etc etc.
 
<the result of a forced landing
Egg had one forced landing. It was caused by vapor lock. Absolutely = NOTHING=20 to do with the lack of bleed line. A day later, Jan made it to the crash = site.=20 Pump would not flow fuel until he cracked the line loose. This is simply = because=20 the inlet to pumps was not wet. He did not understand this. He just = reacted to=20 symptoms. Nothing to do with vapor lock. Remember, this was crash site. = Who=20 knows what attitude plane was at. As I described, if you screwed up your = plumbing from tank to pump, then pump is not self priming.
 
<tested this system on the ground and it works as = advertized
You also test it without the bleed line?
 
FWIW, everything you describe is not = vapor lock,=20 has nothing to do with vapor lock.
 
-al wick
 
----- Original Message -----
From:=20 Mark = Steitle=20
Sent: Wednesday, August 17, = 2011 9:19=20 AM
Subject: [FlyRotary] Re: Dennis = Haverlah=20 Fuel System...or any others, for that matter.

Al,
 
I would think that a well-designed fuel system with the = pumps=20 located as low as possible, in a cool area, and a = return=20 system should not be troubled with vapor = locking.  Although I=20 guess it could happen in Death Valley in August if the a/c is = left out in=20 the sun for 8 hours, and running auto gas.  So far, I haven't had = any=20 problem here in Texas (temps 105* today).   
 
My purpose for installing the bypass circuit was more critical to = safe=20 flight.  (The solution was the result of a forced landing, = or=20 two, in an Eggenfellner Subaru installation.)  During ground = runs,=20 using a 5-gallon can, I found that the efi fuel pumps could not = restore=20 pressure once the tank had been allowed to run dry.  When = this=20 occurred, the EFI pump would suck a big slug of air into the = inlet side=20 of the pump, loose pressure, and being unable to build psi equal = to the=20 pressure regulator setting, it would stop pumping fuel (vapor = lock).  The=20 only way to restore operation was to crack open the system downstream = of the=20 pump until the slug of air could be passed on through the fuel=20 pump.  Not sure this meets your definiton of "vapor lock", = but I=20 think it does, but for a different reason than fuel vapor = pressure.
 
I have tested this system on the ground and it works as = advertized. =20 If the tank runs dry, switched to a full tank, the efi pump will = restore=20 pressure to the system within a few seconds.  I urge all builders = to run=20 this test on their fuel system to determine whether or not their pumps = are=20 able to restore pressure after running a tank dry.  Or, just = don't ever=20 run a tank dry.
 
Mark S.


 
On Wed, Aug 17, 2011 at 10:22 AM, Ernest = Christley=20 <echristley@att.net> = wrote:
Al Wick wrote:
I'm really concerned for some of these fuel = designs. The=20 fuel bleed has nothing to do with vapor lock. Virtually no effect = at=20 all.
 

I don't know why others = are doing=20 it, but for me, the bleed has nothing at all to do with vapor lock.=20  Some conversations have been mixed together, so I can see how = that=20 could be the impression.  The point of the pressure bleed is to = bleed=20 off the pressure after shutdown.

I have a strong, positive = head=20 pressure going into my pumps.  They, and the regulator, are = about 8"=20 directly below the tank.  Excess fuel goes back to the opposite = side of=20 the tank from the pickup, and a single line goes forward to feed the = injectors.  The fuel lines are arranged such that heat soaking = the=20 lines to the point of boiling the gas will push liquid fuel down = hill and=20 behind the firewall, isolating the gaseous gas with its heat at the = top of=20 the line.  Turning the pumps on will pressurize the line to = 55psi,=20 returning most of the gaseous fuel back to a liquid state.  The = ECM is=20 programmed for a longer clearing pulse on hot start.

The = point of the=20 bleed is to allow fuel to move back to the tank.  I had the = issue of a=20 the pressurized lines being perfectly sealed.  The pressurized = fuel was=20 finding the path of least resistance out, which just happened to be = out the=20 injector and into the intake manifold where it sat as a little = puddle.=20  Heat soaking the lines would not push liquid fuel downhill and = back=20 behind the firewall.  It would push more fuel into the = manifold.=20  A puddle of gas sitting in a composite manifold, just above a = hot=20 exhaust stack is just bad mojo.  A poorly sealed regulator = allows the=20 pressure to bleed off in about 5 seconds (give or take), isolating = the hot=20 fuel in front of the firewall, and keeping the rest cool and out of = the=20 intake manifold.

Got nuthin' to do with vapor lock.

--
Homepage:  http://www.flyrotary.com/
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