Return-Path: Received: from mail13.syd.optusnet.com.au ([211.29.132.194] verified) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP-TLS id 729066 for flyrotary@lancaironline.net; Mon, 14 Feb 2005 20:59:37 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.194; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-87-63.dsl.nsw.optusnet.com.au [211.31.87.63]) by mail13.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j1F1wif2021924 for ; Tue, 15 Feb 2005 12:58:49 +1100 Message-ID: <002901c51302$336cae30$3f571fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel System Design - Jet Pump Date: Tue, 15 Feb 2005 12:01:01 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0026_01C51356.0493D6C0" 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 This is a multi-part message in MIME format. ------=_NextPart_000_0026_01C51356.0493D6C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mark/Ed, What's a Jet pump? George ( down under) 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_0026_01C51356.0493D6C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Mark/Ed,
What's a Jet pump?
George ( down under)
 
Good Idea, Mark
 
I think that people get pretty hung = up and=20 adamant about certain things - even though they may indeed = work. While=20 all fuel systems clearly require careful design and construction = attention,=20 some appear to require even more scrutiny.  What I think = sometimes gets=20 folks in trouble is they "copy" a design they have seen/hear = works. =20 However, they seldom ever copy the design faithfully either due to=20 space/configuration constraints - or they have an "improvement" to = it. =20 The bottom line is the system has changed, "Yes, Virginia, it may = really=20 matter as to whether the pickup is at the top vs the bottom,=20 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=20 tank.  So while I do believe his design eliminates (or = certainly=20 diminishes the chance of vapor lock) - you now must carefully = monitor how=20 much fuel is in the return tank.  I believe Tracy uses a = facet pump=20 to move fuel from one tank to the other - which even though unlikely, = could=20 fail leaving fuel unavailable.  I would have to agree though = that=20 scenario certainly would leave you a bit more time to consider your = options -=20 than a faltering engine on take off. 
 
But, yes, it would appear that = the "jet=20 pump" might indeed be a replacement for the facet pump.  = Interesting=20 concept.
 
Ed A 
----- Original Message -----
From:=20 Mark R Steitle =
To: Rotary motors in = aircraft=20
Sent: Monday, February 14, = 2005 4:40=20 PM
Subject: [FlyRotary] Fuel = System Design=20 - Jet Pump

Ed,=20

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

 

Mark S.=20    

 

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