Return-Path: Received: from [65.54.169.53] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 729018 for flyrotary@lancaironline.net; Mon, 14 Feb 2005 20:18:45 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.169.53; envelope-from=lors01@msn.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Mon, 14 Feb 2005 17:18:00 -0800 Message-ID: Received: from 4.174.1.92 by BAY3-DAV23.phx.gbl with DAV; Tue, 15 Feb 2005 01:17:12 +0000 X-Originating-IP: [4.174.1.92] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Fuel System Design - Jet Pump Date: Mon, 14 Feb 2005 20:17:12 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00A8_01C512D2.2B01D660" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0009.2900 Seal-Send-Time: Mon, 14 Feb 2005 20:17:12 -0500 X-OriginalArrivalTime: 15 Feb 2005 01:18:00.0205 (UTC) FILETIME=[3057DBD0:01C512FC] This is a multi-part message in MIME format. ------=_NextPart_000_00A8_01C512D2.2B01D660 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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,=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_00A8_01C512D2.2B01D660 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

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=20 regulator doesn't regulate accurately any more. Remember that = return flow=20 will change with power setting.

Fuel tank levels needs to be controlled in order to eliminate = a 'heavy=20 wing' which is very fatiguing on a long cross country. Aileron = trim can do=20 it but that adds drag. A valve can be used but that adds to = the=20 complexity again.

Tracy

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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