Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 729138 for flyrotary@lancaironline.net; Mon, 14 Feb 2005 22:34:34 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.rr.com [24.74.185.127]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j1F3XjCi024437 for ; Mon, 14 Feb 2005 22:33:46 -0500 (EST) Message-ID: <000a01c5130f$2eb88910$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Jet Pump Date: Mon, 14 Feb 2005 22:33:54 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01C512E5.441B2E90" 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_0007_01C512E5.441B2E90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable George, its actually a siphon pump for a two tank system. They use the = fuel being released by the fuel pressure regulator in one tank and run = it through a restriction ( a Ventura) and it flows through the Ventura = (returning back into the main tank) it develops a low pressure, this low = pressure region of the jet is plumbed to the second tank. The "suction" = action pulls fuel from the second tank into the main tank where the EFI = pump, "Jet pump" and fuel pressure regulator are all located. This is = used as a "transfer" pump but does not require another "electric" pump = such as a facet pump that many of us use as either a boost pump or fuel = transfer pump. Interesting concept for sure - but if for some reason = something would break the "siphon" effect (say trash in the Ventura) = then NO fuel transfer from the second tank. But, then a transfer pump = can fail as well - sigh nothing never breaks {:>) Hope this explains it well enough. Ed A ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Monday, February 14, 2005 9:01 PM Subject: [FlyRotary] Re: Fuel System Design - Jet Pump 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_0007_01C512E5.441B2E90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
George, its actually a siphon pump for = a two tank=20 system.  They use the fuel being released by the fuel pressure = regulator in=20 one tank and run it through a restriction ( a Ventura) and it flows = through=20 the Ventura (returning back into the main tank) it develops a low = pressure,=20 this low pressure region of the jet is plumbed to the second tank.  = The=20 "suction" action pulls fuel from the second tank into the main tank = where the=20 EFI pump, "Jet pump" and fuel pressure regulator are all located.  = This is=20 used as a "transfer" pump but does not require another "electric" pump = such as a=20 facet pump that many of us use as either a boost pump or fuel transfer = pump.=20 Interesting concept for sure - but if for some reason something would = break the=20 "siphon" effect (say trash in the Ventura) then NO fuel transfer from = the second=20 tank. But, then a transfer pump can fail as well - sigh nothing = never=20 breaks {:>)
 
Hope this explains it well = enough.
 
Ed A
----- Original Message -----
From:=20 George=20 Lendich
Sent: Monday, February 14, 2005 = 9:01=20 PM
Subject: [FlyRotary] Re: Fuel = System=20 Design - Jet Pump

 
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=20 end up 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=20 monitor how much fuel is in the return tank.  I = believe Tracy=20 uses a facet pump to move fuel from one tank to the other - which = even=20 though unlikely, could fail leaving fuel unavailable.  I = would=20 have to agree though that scenario certainly would leave you a bit = more time=20 to consider your options - than a faltering engine on take=20 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=20 Design - 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=20 the need for the facet pump in a design such as Tracy=92s which = would=20 simplify things even more than Tracy=92s system already = does.  Of=20 course, as in Tracy=92s design, this would = eliminate the=20 need for the fuel selector valve too.  As it was designed to = do, the=20 Jet Pump would be powered by excess fuel from the main fuel pump = located=20 in the left tank.  Fuel from the other (right) wing tank = would be=20 drawn into the main (left) tank by the Jet Pump.  To prevent=20 overfilling the main tank, transfer could be controlled by a small = 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=20 the right tank.  I guess this idea could also be used with a = sump=20 tank.  Time for a sanity check.  =

 

Mark S.=20    

 

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