X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: <13brv3@bellsouth.net> Received: from imf21aec.mail.bellsouth.net ([205.152.59.69] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 950424 for flyrotary@lancaironline.net; Thu, 19 May 2005 18:10:17 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.69; envelope-from=13brv3@bellsouth.net Received: from ibm63aec.bellsouth.net ([65.6.194.9]) by imf21aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050519220932.OFCW25529.imf21aec.mail.bellsouth.net@ibm63aec.bellsouth.net> for ; Thu, 19 May 2005 18:09:32 -0400 Received: from rd ([65.6.194.9]) by ibm63aec.bellsouth.net (InterMail vG.1.02.00.01 201-2136-104-101-20040929) with ESMTP id <20050519220931.QDZL24612.ibm63aec.bellsouth.net@rd> for ; Thu, 19 May 2005 18:09:31 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: MAP measurement Date: Thu, 19 May 2005 17:09:47 -0500 Message-ID: <002001c55cbf$785f7d40$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0021_01C55C95.8F897540" 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 V6.00.2900.2527 This is a multi-part message in MIME format. ------=_NextPart_000_0021_01C55C95.8F897540 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Rusty, did you get my note regarding measuring the total pressure with = pitot style probe? Bernie Hi Bernie,=20 =20 I got it, but I didn't really "get it". I just read it a couple more = times, and think I might finally understand what you're saying! =20 It sounds like you're saying that a pitot probe will give a better = reading of the actual (total) pressure of air in the runner. You mentioned that = the pitot reading in the plenum will be the same as the reading in the = runner, minus frictional losses. =20 =20 This makes sense from what I've seen so far. About the only thing I'm = sure about intakes is that smooth transitions are really important. Now I = see that smoothing the flow is reducing the losses, and allowing more of the original energy to be retained as useful air volume that makes it into = the rotor housing when the port opens. =20 =20 So, if you had a perfect intake, you would measure the same pitot = pressure inside the runner, as you would read ambient static pressure at the = inlet to the TB. Since the TWM TB apparently has an excellent "static" style = port, I'm only seeing part of the picture, which makes it look like my intake = is lousy. =20 =20 From all this, it would seem like the real test would be to put a static style port in the runner, and see what it measures compared to ambient. = If this is near ambient, at WOT, then the intake is not causing a = significant restriction in power. If the pressure drop is still significant, then = it proves I've got too much restriction. =20 =20 Would you agree with that test? If so, I can pull one of the plugs out = of an injector port on the TWM, and install a pitot tube that reaches down = into the air stream temporarily for testing. That would end up about the = same location as the stock MAP port on the TB. =20 =20 I can't help but laugh at myself for all this effort to increase the = MAP. It all came to a head again when I wasn't making the RPM's I expected to make with the new engine and prop changes. I bet if I spent the same = amount of time flying, as I have thinking about the intake "problem", the = engine would have broken in well enough to get all the RPM I originally = expected. =20 =20 Thanks for making me go look at your message again.=20 =20 Rusty (in need of therapy) =20 =20 =20 =20 =20 ------=_NextPart_000_0021_01C55C95.8F897540 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Rusty, did you get my note regarding measuring the = total=20 pressure with pitot style probe?

Bernie

Hi = Bernie,=20
 
I got = it, but I didn't=20 really "get it".  I just read it a couple more times, and = think I=20 might finally understand what you're saying!
 
It = sounds like you're=20 saying that a pitot probe will give a better reading of the=20 actual (total) pressure of air in the runner.  You mentioned = that the=20 pitot reading in the plenum will be the same as the reading in the = runner,=20 minus frictional losses. 
 
This = makes sense from=20 what I've seen so far.  About the only thing I'm=20 sure about intakes is that smooth transitions are really=20 important.  Now I see that smoothing the flow = is reducing=20 the losses, and allowing more of the original energy to be retained = as=20 useful air volume that makes it into the rotor housing when the port=20 opens.  
 
So, if = you had a perfect=20 intake, you would measure the same pitot pressure inside the = runner, as you=20 would read ambient static pressure at the inlet to the TB.  = Since the=20 TWM TB apparently has an excellent "static" style port, I'm only = seeing=20 part of the picture, which makes it look like my intake is=20 lousy.  
 
From all = this, it would=20 seem like the real test would be to put a static style port in the = runner, and=20 see what it measures compared to ambient.  If this is near ambient, = at WOT,=20 then the intake is not causing a significant restriction in power.  = If=20 the pressure drop is still significant, then it proves I've got too = much=20 restriction.  
 
Would = you agree with=20 that test?  If so, I can pull one of the plugs out of=20 an injector port on the TWM, and install a pitot = tube that=20 reaches down into the air stream temporarily for = testing.   That=20 would end up about the same location as the stock MAP port on the=20 TB.  
 
I can't help but laugh at myself = for all=20 this effort to increase the MAP.  It all came to a head again = when I=20 wasn't making the RPM's I expected to make with the new engine and = prop=20 changes.  I bet if I spent the same amount of time flying, as I = have=20 thinking about the intake "problem", the engine would have broken in = well enough=20 to get all the RPM I originally expected. 
 
Thanks = for making me go=20 look at your message again.
 
Rusty (in need of = therapy)    
 
 
 
 
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