X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from m15.nyc.untd.com ([64.136.22.78] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with SMTP id 949229 for flyrotary@lancaironline.net; Wed, 18 May 2005 17:14:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.22.78; envelope-from=jbker@juno.com Received: from m15.nyc.untd.com (localhost [127.0.0.1]) by m15.nyc.untd.com with SMTP id AABBJZM9WADZJHES for (sender ); Wed, 18 May 2005 14:13:24 -0700 (PDT) X-UNTD-OriginStamp: Y+Mfppm2QyGfnY/dq+iW1STK7Ff8JhJ94hQW2ycI0/6efUqEdxxyxQ== Received: (from jbker@juno.com) by m15.nyc.untd.com (jqueuemail) id KTBHGTGH; Wed, 18 May 2005 14:12:44 PDT To: flyrotary@lancaironline.net Date: Wed, 18 May 2005 17:12:06 -0400 Subject: Re: [FlyRotary] Re: More MAP measurement questions(Ram pressure) Message-ID: <20050518.171207.304.6.JBKER@juno.com> X-Mailer: Juno 5.0.33 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=--__JNP_000_4184.3ca7.7378 X-Juno-Line-Breaks: 8-6,11-14,23-24,25-32767 From: WALTER B KERR X-ContentStamp: 7:3:308638630 X-UNTD-Peer-Info: 127.0.0.1|localhost|m15.nyc.untd.com|jbker@juno.com This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ----__JNP_000_4184.3ca7.7378 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Thanks for the comments. What are the inside diameters of your tubes (assuming primary and secondary are different)? Also, what RPM are you seeing static, when you said you measured essentially 30"? Do you think you could be getting any ram-air effect in your MAP port with the open end pointing somewhat into the air stream? -------------------------------------------------------- I do not understand your question Rusty. A good pitot pressure measures almost 100% ram pressure. This is exactly what plenum static pressure is equal to. There is nothing adding work or pressure ratio to the air between the plenum or T/B and the runner. You can not measure a pressure higher than what is in large plenum, ie very low average velocity through it. Apparently some think there is a magic here that the ram pressure is higher than the stopped air pressure. If you put a static probe, a pitot probe, and a downstream pitot probe in a system they will all read the same number (ignoring frictional losses) Bernie ----__JNP_000_4184.3ca7.7378 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: quoted-printable

<= FONT=20 face=3DArial color=3D#ff0000>Thanks for the comments. What are the = inside=20 diameters of your tubes (assuming primary and secondary are different)?&= nbsp;=20 Also, what RPM are you seeing static, when you said you measured = essentially=20 30"? Do you think you could be getting any ram-air effect in = your=20 MAP port with the open end pointing somewhat into the air=20 stream?

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<= FONT=20 face=3DArial color=3D#ff0000>I do not understand your question Rusty. A = good pitot=20 pressure measures almost 100% ram pressure. This is exactly what plenum = static=20 pressure is equal to. There is nothing adding work or pressure ratio to the= air=20 between the plenum or T/B and the runner. You can not measure a pressure = higher=20 than what is in large plenum, ie very low average velocity through it.=20 Apparently some think there is a magic here that the ram pressure is higher= than=20 the stopped air pressure. If you put a static probe, a pitot probe, and a=20 downstream pitot probe in a system they will all read the same number=20 (ignoring frictional losses)

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<= FONT=20 face=3DArial color=3D#ff0000>Bernie

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