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Return-Path: Received: from fed1rmmtao12.cox.net ([68.230.241.27] verified) by logan.com (CommuniGate Pro SMTP 4.2) with ESMTP id 359788 for flyrotary@lancaironline.net; Tue, 10 Aug 2004 13:02:14 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.27; envelope-from=daveleonard@cox.net Received: from davidandanne ([68.111.224.107]) by fed1rmmtao12.cox.net (InterMail vM.6.01.03.02.01 201-2131-111-104-103-20040709) with SMTP id <20040810170142.OMQA19941.fed1rmmtao12.cox.net@davidandanne> for ; Tue, 10 Aug 2004 13:01:42 -0400 From: "DaveLeonard" To: "Rotary motors in aircraft" Subject: RE: [FlyRotary] Re: returnless fuel system Date: Tue, 10 Aug 2004 10:01:47 -0700 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0045_01C47EC1.0C4DCDF0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_0045_01C47EC1.0C4DCDF0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit MessageYes, its true Rusty. With both pumps on I show >80 gph going through the return line. I put the fuel flow sensor in my return line for a few reasons: 1) It came with my engine monitor so needed to put this $250 sensor somewhere 2) Along with fuel pressure, it is a way to check and make sure the entire fuel system is working. If a pumps starts to fail via low output or there is a clog in the filter or elsewhere in the system it will manifest with decreased flow but maybe not in the fuel pressure. 3) It gives me a rough gauge of fuel consumption. For example, I know that it reads 52 gal/hr at idle. In a high power climb it reads, say, 38gal/hr which means that I am burning something less that 14 gal/hr. Keeping the throttle setting the same I can lean the mixture and watch the return flow climb up to 44 or even 46 gal/hr (my fuel burn has now dropped to about 6-8 gal/hr). Of note, these numbers are just rough estimates because the output of the pumps changes pretty significantly with the pressure they are seeing. By making adjustments to the fuel pressure regulator with the engine off I could get the flow to drop to 20-30 gph by increasing the fuel pressure to 60psi. Since my fuel pressure varies with MAP so will my baseline fuel flow. Also, buss voltage changes the output of the pumps. By turning off the alternator at idle the return flow with drop by about 5 gal/hr. Yes, I believe that we are well mixed. So much so that I have never sampled my fuel for water. I am even thinking about removing the sample ports and putting in low-drag plugs. Every bit helps :-) Dave Leonard (still waiting for a replacement oil cooler) during his flight with Dave Leonard, he personally observed 45 gallons per hour fuel return with one of Tracy's pumps on and 80 gallons per hour with both pumps on!! Dave has a flow meter on his return line. Wow, is that true Dave? That seems high, but I have no way of measuring it. I run both pumps all the time (aside from testing them individually during preflight), so I guess my fuel stays pretty well stirred :-) Rusty (yes I know you don't need to run both all the time) ------=_NextPart_000_0045_01C47EC1.0C4DCDF0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message

Yes,=20 its true Rusty. With both pumps on I show >80 gph going through = the=20 return line. I put the fuel flow sensor in my return line for a = few=20 reasons:

1) It=20 came with my engine monitor so needed to put this $250 sensor=20 somewhere

2)=20 Along with fuel pressure, it is a way to check and make sure the entire = fuel=20 system is working. If a pumps starts to fail via low output or = there is a=20 clog in the filter or elsewhere in the system it will manifest with = decreased=20 flow but maybe not in the fuel pressure.

3) It=20 gives me a rough gauge of fuel consumption. For example, I know=20 that it reads 52 gal/hr at idle. In a high power climb it = reads, say,=20 38gal/hr which means that I am burning something less that 14 = gal/hr. =20 Keeping the throttle setting the same I can lean the mixture and watch = the=20 return flow climb up to 44 or even 46 gal/hr (my fuel burn has now = dropped to=20 about 6-8 gal/hr).

Of=20 note, these numbers are just rough estimates because the output of the = pumps=20 changes pretty significantly with the pressure they are seeing. By = making=20 adjustments to the fuel pressure regulator with the engine off I could = get the=20 flow to drop to 20-30 gph by increasing the fuel pressure to = 60psi. Since=20 my fuel pressure varies with MAP so will my baseline fuel=20 flow.

Also,=20 buss voltage changes the output of the pumps. By turning off = the=20 alternator at idle the return flow with drop by about 5=20 gal/hr.

Yes, I=20 believe that we are well mixed. So much so that I have never = sampled my=20 fuel for water. I am even thinking about removing the sample ports = and=20 putting in low-drag plugs. Every bit helps :-)

Dave=20 Leonard (still waiting for a replacement oil cooler)

during his flight with Dave=20 Leonard, he personally observed 45 gallons per hour fuel return = with one=20 of Tracy's pumps on and 80 gallons per hour with both pumps on!! = Dave=20 has a flow meter on his return line.

Wow, is that true Dave? That seems = high, but I=20 have no way of measuring it. I run both pumps all the time = (aside from=20 testing them individually during preflight), so I guess my fuel = stays=20 pretty well stirred :-)

Rusty (yes I know you don't need to run = both all the=20 time)

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