Return-Path: Received: from relay03.roc.ny.frontiernet.net ([66.133.182.166] verified) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 729222 for flyrotary@lancaironline.net; Tue, 15 Feb 2005 00:39:09 -0500 Received-SPF: pass receiver=logan.com; client-ip=66.133.182.166; envelope-from=canarder@frontiernet.net Received: from filter03.roc.ny.frontiernet.net (filter03.roc.ny.frontiernet.net [66.133.183.70]) by relay03.roc.ny.frontiernet.net (Postfix) with ESMTP id 0BAE73580FB for ; Tue, 15 Feb 2005 05:38:26 +0000 (UTC) Received: from relay03.roc.ny.frontiernet.net ([66.133.182.166]) by filter03.roc.ny.frontiernet.net (filter03.roc.ny.frontiernet.net [66.133.183.70]) (amavisd-new, port 10024) with LMTP id 13957-98-92 for ; Tue, 15 Feb 2005 05:38:25 +0000 (UTC) Received: from [127.0.0.1] (67-137-75-55.dsl2.cok.tn.frontiernet.net [67.137.75.55]) by relay03.roc.ny.frontiernet.net (Postfix) with ESMTP id 42271358148 for ; Tue, 15 Feb 2005 05:38:24 +0000 (UTC) Message-ID: <42118ACC.1050904@frontiernet.net> Date: Mon, 14 Feb 2005 23:38:20 -0600 From: Jim Sower User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Fuel System Design - Jet Pump References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------080007030006060503000306" X-Antivirus: avast! (VPS 0506-1, 02/11/2005), Outbound message X-Antivirus-Status: Clean X-Virus-Scanned: by amavisd-new-20040701 (2.0) at filter03.roc.ny.frontiernet.net This is a multi-part message in MIME format. --------------080007030006060503000306 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Is there compelling evidence that a jet pump will last longer than a=20 Facet pump? What do they cost?=20 Mark R Steitle wrote: >Tracy, >I believe the Jet Pump works off fuel rerouted from the main pump, not t= he return fuel. You may need a higher gpm pump in order to provide enoug= h flow for WOT operations though. If you controlled the transfer process= with a couple of sensors in the main tank, one for upper limit and anoth= er for low limit, it could be a fully automatic system. > >Mark S. =20 > > >-----Original Message----- >From: Rotary motors in aircraft on behalf of Tracy Crook >Sent: Mon 2/14/2005 7:17 PM >To: Rotary motors in aircraft >Subject: [FlyRotary] Re: Fuel System Design - Jet Pump >=20 >Thoughts on the jet pump: > >Jet pump requires a restriction (jet) in the return line. ANY pressure = in the return line adds to the regulated fuel pressure which means your r= egulator doesn't regulate accurately any more. Remember that return flow= will change with power setting. > >Fuel tank levels needs to be controlled in order to eliminate a 'heavy w= ing' which is very fatiguing on a long cross country. Aileron trim can d= o it but that adds drag. A valve can be used but that adds to the comple= xity again. > >Tracy > > > Ed,=20 > > Thanks for that excellent article on fuel system design. In reading t= hrough it, on page 5, I came to the description of the jet pump and had a= thought (that alone is a scary thing). I was thinking that this could b= e used to eliminate the need for the facet pump in a design such as Tracy= 's which would simplify things even more than Tracy's system already does= =2E Of course, as in Tracy's design, this would eliminate the need for t= he fuel selector valve too. As it was designed to do, the Jet Pump would= be powered by excess fuel from the main fuel pump located in the left ta= nk. Fuel from the other (right) wing tank would be drawn into the main (= left) tank by the Jet Pump. To prevent overfilling the main tank, transf= er could be controlled by a small solenoid valve. Since you would be dra= wing fuel from the right tank pretty much all the time, it may be possibl= e to route the return fuel to the right tank. I guess this idea could al= so be used with a sump tank. Time for a sanity check. =20 > > =20 > > Mark S. =20 > > =20 > > =20 > >------------------------------------------------------------------------= > > =20 > >>> Homepage: http://www.flyrotary.com/ >>> Archive: http://lancaironline.net/lists/flyrotary/List.html >>> =20 >>> --------------080007030006060503000306 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Is there compelling evidence that a jet pump will last longer than a Facet pump?  What do they cost? 

Mark R Steitle wrote: 
Tracy,
I believe the Jet Pump works off fuel rerouted from the main pump, not the return fuel.  You may need a higher gpm pump in order to provide enough flow for WOT operations though.  If you controlled the transfer process with a couple of sensors in the main tank, one for upper limit and another for low limit, it could be a fully automatic system.

Mark S.  


-----Original Message-----
From: Rotary motors in aircraft on behalf of Tracy Crook
Sent: Mon 2/14/2005 7:17 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Fuel System Design - Jet Pump
 
Thoughts on the jet pump:

Jet pump requires a restriction (jet) in the return line.  ANY pressure in the return line adds to the regulated fuel pressure which means your regulator doesn't regulate accurately any more.  Remember that return flow will change with power setting.

Fuel tank levels needs to be controlled in order to eliminate a 'heavy wing' which is very fatiguing on a long cross country.  Aileron trim can do it but that adds drag.  A valve can be used but that adds to the complexity again.

Tracy


  Ed, 

  Thanks for that excellent article on fuel system design.  In reading through it, on page 5, I came to the description of the jet pump and had a thought (that alone is a scary thing).  I was thinking that this could be used to eliminate the need for the facet pump in a design such as Tracy's which would simplify things even more than Tracy's system already does.  Of course, as in Tracy's design, this would eliminate the need for the fuel selector valve too.  As it was designed to do, the Jet Pump would be powered by excess fuel from the main fuel pump located in the left tank.  Fuel from the other (right) wing tank would be drawn into the main (left) tank by the Jet Pump.  To prevent overfilling the main tank, transfer could be controlled by a small solenoid valve.  Since you would be drawing fuel from the right tank pretty much all the time, it may be possible to route the return fuel to the right tank.  I guess this idea could also be used with a sump tank.  Time for a sa
nity check.  

   

  Mark S.    

   

  

  
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