Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 728989 for flyrotary@lancaironline.net; Mon, 14 Feb 2005 19:22:43 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.rr.com [24.74.185.127]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j1F0Lqee028689 for ; Mon, 14 Feb 2005 19:21:54 -0500 (EST) Message-ID: <000e01c512f4$6023db50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Fuel System Design - Jet Pump Date: Mon, 14 Feb 2005 19:22:02 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01C512CA.760C0480" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0009_01C512CA.760C0480 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Good Idea, Mark I think that people get pretty hung up and adamant about certain things = - even though they may indeed work. While all fuel systems clearly = require careful design and construction attention, some appear to = require even more scrutiny. What I think sometimes gets folks in = trouble is they "copy" a design they have seen/hear works. However, = they seldom ever copy the design faithfully either due to = space/configuration constraints - or they have an "improvement" to it. = The bottom line is the system has changed, "Yes, Virginia, it may really = matter as to whether the pickup is at the top vs the bottom, etc. ". Even Tracy's system can byte you if you are not careful. You must pay = attention to fuel transfer or you can end up with the return fuel = pushing out the vent of the return tank. So while I do believe his = design eliminates (or certainly diminishes the chance of vapor lock) - = you now must carefully monitor how much fuel is in the return tank. I = believe Tracy uses a facet pump to move fuel from one tank to the other = - which even though unlikely, could fail leaving fuel unavailable. I = would have to agree though that scenario certainly would leave you a bit = more time to consider your options - than a faltering engine on take = off.=20 But, yes, it would appear that the "jet pump" might indeed be a = replacement for the facet pump. Interesting concept. Ed A =20 ----- Original Message -----=20 From: Mark R Steitle=20 To: Rotary motors in aircraft=20 Sent: Monday, February 14, 2005 4:40 PM Subject: [FlyRotary] Fuel System Design - Jet Pump Ed,=20 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 sanity = check. =20 =20 Mark S. =20 =20 ------=_NextPart_000_0009_01C512CA.760C0480 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Good Idea, Mark
 
I think that people get pretty hung up = and adamant=20 about certain things - even though they may indeed work. While all = fuel=20 systems clearly require careful design and construction attention, some = appear=20 to require even more scrutiny.  What I think sometimes gets folks = in=20 trouble is they "copy" a design they have seen/hear works.  = However, they=20 seldom ever copy the design faithfully either due to space/configuration = constraints - or they have an "improvement" to it.  The bottom line = is the=20 system has changed, "Yes, Virginia, it may really matter as to whether = the=20 pickup is at the top vs the bottom, etc. ".
 
Even Tracy's system can byte you if you = are not=20 careful.  You must pay attention to fuel transfer or you can = end up=20 with the return fuel pushing out the vent of the return = tank.  So=20 while I do believe his design eliminates (or certainly diminishes the = chance of=20 vapor lock) - you now must carefully monitor how much fuel is in = the return=20 tank.  I believe Tracy uses a facet pump to move fuel from one = tank to=20 the other - which even though unlikely, could fail leaving fuel=20 unavailable.  I would have to agree though that scenario certainly = would=20 leave you a bit more time to consider your options - than a faltering = engine on=20 take off. 
 
But, yes, it would appear that the = "jet pump"=20 might indeed be a replacement for the facet pump.  Interesting=20 concept.
 
Ed A 
----- Original Message -----
From:=20 Mark R Steitle =
Sent: Monday, February 14, 2005 = 4:40=20 PM
Subject: [FlyRotary] Fuel = System Design -=20 Jet Pump

Ed, =

Thanks for that = excellent article=20 on fuel system design.  In reading through it, on page 5, I came = to the=20 description of the jet pump and had a thought (that alone is a scary=20 thing).  I was thinking that this could be used to eliminate the = need for=20 the facet pump in a design such as Tracy=92s which would simplify = things even=20 more than Tracy=92s system already does.  Of course, as in = Tracy=92s = design, this=20 would eliminate the need for the fuel selector valve too.  As it = was=20 designed to do, the Jet Pump would be powered by excess fuel from the = main=20 fuel pump located in the left tank.  Fuel from the other (right) = wing=20 tank would be drawn into the main (left) tank by the Jet Pump.  = To=20 prevent overfilling the main tank, transfer could be controlled by a = small=20 solenoid valve.  Since you would be drawing fuel from the right = tank=20 pretty much all the time, it may be possible to route the return fuel = to the=20 right tank.  I guess this idea could also be used with a sump = tank. =20 Time for a sanity check. 

 

Mark S.=20    

 

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