Return-Path: <13brv3@bellsouth.net> Received: from imf24aec.mail.bellsouth.net ([205.152.59.72] verified) by logan.com (CommuniGate Pro SMTP 4.2) with ESMTP id 373563 for flyrotary@lancaironline.net; Sat, 21 Aug 2004 15:39:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.72; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf24aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040821193900.SUSR1756.imf24aec.mail.bellsouth.net@rd> for ; Sat, 21 Aug 2004 15:39:00 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: EM-2 MAP readings Date: Sat, 21 Aug 2004 14:39:19 -0500 Message-ID: <000c01c487b6$8d412170$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01C4878C.A46B1970" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_000D_01C4878C.A46B1970 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hmm, Weber was pretty much upfront with the fact that their TB ports were only for balancing idle and shouldn't be relied upon for accurate readings at any sort of power setting. Perhaps the TWM port is placed differently than the Weber TB. I'm still skeptical, but I can't think of any way to prove whether = they're correct or not. =20 IMHO, I think your 42s should do just fine at the revs you're turning. In fact, I think the intake charge velocity created by the 42mm tract may help you. I have info here (not in the attic!) reference intake VNE as well as a link to a calculator for gas velocity in a pipe. The link is http://not2fast.com/gasflow/velocity.shtml - you'll have to do the metric/English conversion thing but the math is sound. I'll post the gas velocity thing later when I can get to the info. I want to say 600 f/s but will confirm. =20 Neat calculator, but let's see if I'm using this correctly. =20 =20 I'm looking at one rotor, since each TB bore and intake runner feeds = only one rotor. The displacement of a 13B is 1.3 liters, so one rotor is .65 liters. My handy converter turns this into .023 cubic feet per rotor, = per revolution. Multiply this by 7000 rpm, and I get 161 cubic feet per = minute. I enter this into the gas flow program, leave the temp at 100F, and put = in the runner ID of 1.625". That gives me a mean velocity of 186 ft/sec. = =20 =20 From the notes at the bottom of the program screen, and your = recollection of 600 fps, my 186 fps figure doesn't appear to be stressing my intake size = at all. The real question is- did I screw something up in the way I = figured this?=20 =20 Feeling better about my intake all the time. Pity the area is covered = with thunderstorms today. I really don't want to test my new XM weather that = bad :-) =20 Thanks, Rusty (replacing home security system destroyed by lightning) =20 =20 ------=_NextPart_000_000D_01C4878C.A46B1970 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Hmm, Weber was pretty much upfront with the fact that = their TB=20 ports
were only for balancing idle and shouldn't be relied upon for=20 accurate
readings at any sort of power setting. Perhaps the TWM = port  is=20 placed
differently than the Weber TB.

I'm = still skeptical, but=20 I can't think of any way to prove whether they're correct or=20 not. 

 IMHO, I think your 42s should do = just
fine at=20 the revs you're turning. In fact, I think the intake charge
velocity = created=20 by the 42mm tract may help you. I have info here (not
in the attic!)=20 reference intake VNE as well as a link to a calculator
for gas = velocity in a=20 pipe. The link is
http://not2fast.com/g= asflow/velocity.shtml=20 - you'll have to do the
metric/English conversion thing but the math = is=20 sound. I'll post the gas
velocity  thing later when I can get to = the=20 info. I want to say 600 f/s
but will confirm.
 
Neat = calculator, but=20 let's see if I'm using this correctly. 
 
I'm = looking at one=20 rotor, since each TB bore and intake runner feeds only=20 one rotor.  The displacement of a 13B is 1.3 liters, so = one rotor=20 is .65 liters.  My handy converter turns this into .023 cubic = feet per=20 rotor, per revolution.  Multiply this by 7000 rpm, and I = get 161=20 cubic feet per minute.  I enter this into the gas flow = program, leave=20 the temp at 100F, and put in the runner ID of 1.625".   = That=20 gives me a mean velocity of 186 ft/sec.  =   
 
From the notes at the bottom of=20 the program screen, and your recollection of 600 fps, my 186 fps = figure=20 doesn't appear to be stressing my intake size at all.  = The real=20 question is- did I screw something up in the way I = figured=20 this? 
 
Feeling better about my intake = all the=20 time.  Pity the area is covered with thunderstorms today.  I = really=20 don't want to test my new XM weather that bad :-)
 
Thanks,
Rusty (replacing home security = system=20 destroyed by lightning)
 
 
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