Return-Path: <13brv3@bellsouth.net> Received: from imf20aec.mail.bellsouth.net ([205.152.59.68] verified) by logan.com (CommuniGate Pro SMTP 4.3c2) with ESMTP id 763698 for flyrotary@lancaironline.net; Mon, 28 Feb 2005 18:30:23 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.68; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf20aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050228232939.VGHS1995.imf20aec.mail.bellsouth.net@rd> for ; Mon, 28 Feb 2005 18:29:39 -0500 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: flow measurements Date: Mon, 28 Feb 2005 17:30:22 -0600 Message-ID: <005b01c51ded$7968e7a0$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_005C_01C51DBB.2ECE77A0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_005C_01C51DBB.2ECE77A0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable PPump manufacturers provide flow charts that will give you the flow rate against a head pressure. Davie-Craig's chart even provides this information for various voltage levels.=20 Measuring a differential pressure across the pump and it's input voltage is trivial enough. Reference the chart, and (unless someone is lying) you have a dependable flow rate. =20 Why use charts, and pressure, and voltages to calculate what I can = directly measure with a flow meter? =20 =20 The one caveat is that the flow meters are all calibrated to the = specific gravity of water, so they won't be completely accurate with Evan's NPG. = I'm sure there's a conversion if I look up the specific gravity of Evan's, = or just ask them to convert it, but getting a directly measured number will = be the place to start. =20 =20 The next problem is that this number means nothing, since we don't have = a known minimum flow number to shoot for. People have measured the stock flow, but no one can say if it's necessary to have that much, or just a necessary evil of providing flow at idle, and being forced to also run = 7500 rpm. =20 =20 Still looking at flow meters anyway. BTW, thanks for the info Todd, but = I can't find a price on those meters. I also suspect they're fairly = pricey. I'm looking at something mechanical, to read directly, but I'm having trouble finding something with enough range. =20 =20 Hey Todd. Since you flew with the flow meter hooked to your EM-2, just = post the datalogs of your flights. Oooops, that's right, we don't have a datalog feature :-) =20 =20 Rusty (it's Todd's fault, really) =20 ------=_NextPart_000_005C_01C51DBB.2ECE77A0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

PPump manufacturers provide flow charts
that will = give you=20 the flow rate against a head pressure.  Davie-Craig's
chart even = provides this information for various voltage levels. 
Measuring = a=20 differential pressure across the pump and it's input voltage
is = trivial=20 enough.   Reference the chart, and (unless someone is = lying)
you=20 have a dependable flow rate.

 
Why use = charts, and=20 pressure, and voltages to calculate what I can directly = measure with a=20 flow meter? 
 
The one = caveat is that=20 the flow meters are all calibrated to the specific gravity of = water, so=20 they won't be completely accurate with Evan's NPG.  I'm sure = there's a=20 conversion if I look up the specific gravity of Evan's, or just ask them = to=20 convert it, but getting a directly measured number will be the place to=20 start.   
 
The next = problem is that=20 this number means nothing, since we don't have a known minimum flow = number=20 to shoot for.  People have measured the stock flow, but no one can = say if=20 it's necessary to have that much, or just a necessary evil of = providing=20 flow at idle, and being forced to also run 7500 rpm.  =
 
Still = looking at flow=20 meters anyway.  BTW, thanks for the info Todd, but I can't find a = price on=20 those meters.  I also suspect they're fairly pricey.  I'm = looking at=20 something mechanical, to read directly, but I'm having trouble finding = something=20 with enough range.  
 
Hey = Todd.  Since=20 you flew with the flow meter hooked to your EM-2, just post = the=20 datalogs of your flights.   Oooops, that's right, = we don't have a=20 datalog feature  :-)  
 
Rusty = (it's Todd's=20 fault, really) 



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