X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2399214 for flyrotary@lancaironline.net; Sun, 21 Oct 2007 19:42:55 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta01.mail.rr.com with SMTP id <20071021234218.YLAK6760.cdptpa-omta01.mail.rr.com@edward2> for ; Sun, 21 Oct 2007 23:42:18 +0000 Message-ID: <001201c8143b$bc992c00$2502a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: ATMOSPHERIC PRESSURE & ENGINE HORSEPOWER AT GROUND LEVEL Date: Sun, 21 Oct 2007 19:40:17 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01C8141A.35426CB0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01C8141A.35426CB0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable ----- Original Message -----=20 From: Lehanover@aol.com=20 To: Rotary motors in aircraft=20 Sent: Sunday, October 21, 2007 7:28 PM Subject: [FlyRotary] Re: ATMOSPHERIC PRESSURE & ENGINE HORSEPOWER AT = GROUND LEVEL In a message dated 10/21/2007 5:57:20 P.M. Eastern Daylight Time, = eanderson@carolina.rr.com writes: That is very interesting, Yvon. My calculation shows that if you were turning 5000 rpm when manifold = pressure was 30.5"Hg you would have been flowing approx 17.20 lbm of = air per=20 minute. If the pressure drops to 29.4" Hg (and all else the same) , = you=20 would now have to turn 5200 rpm to get the same air flow of 17.20 = lbm/min,=20 so there is indeed an 200 rpm difference to get the same air mass = flow.=20 Very interesting. Thanks for sharing. Ed All dyno runs, must be corrected to sea level standard day, so that = there will be some usable data day to day to account for temperature, = humidity, and barometric pressure. Actual HP goes up and down with = changes in all of these factors. Raw torque numbers are meaningless = until corrected as above.=20 Like the RPM drop when you check the carb heat. And the reason you = lean the mixture as you climb. On a Southwest 737 we landed at the old Denver, and before we pushed = back with full fuel and seats, the ticket agent got on the PA and asked = for 6 people to volunteer to get off and catch the next plane, because = now the plane was too heavy to legally leave Denver. Because it was 102 = degrees outside.=20 The wife and I held out for a round trip each to anywhere in the = system. On the way off the plane, we were handed a magnum of champagne. = We went to the ticket counter, then to the very next gate, and got on a = plane that was a nonstop to Columbus Ohio. There were 12 people on that = plane. The plane we got off of landed in Chicago and got stuck there for = three hours in thunder storms.=20 Life is good. Lynn E. Hanover Yes, apples to apples comparisons requires keeping accurate track of = all those varibles - especially if you want to determine if changes you = made actually produced and improvement or just atmosphere conditions. By the way, Lynn, did the Champagne help the 3 hour layover in = Chicago {:>)???? Ed Ed -------------------------------------------------------------------------= ----- See what's new at AOL.com and Make AOL Your Homepage. ------=_NextPart_000_000F_01C8141A.35426CB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
----- Original Message -----
From:=20 Lehanover@aol.com
Sent: Sunday, October 21, 2007 = 7:28=20 PM
Subject: [FlyRotary] Re: = ATMOSPHERIC=20 PRESSURE & ENGINE HORSEPOWER AT GROUND LEVEL

In a message dated 10/21/2007 5:57:20 P.M. Eastern Daylight Time, = eanderson@carolina.rr.com=20 writes:
That=20 is very interesting, Yvon.

My calculation shows that if you = were=20 turning 5000 rpm when manifold
pressure was 30.5"Hg you would = have been=20 flowing approx 17.20 lbm of air per
minute.  If the = pressure drops=20 to 29.4" Hg (and all else the same) , you
would now have to turn = 5200=20 rpm to get the same air flow of 17.20 lbm/min,
so there is = indeed an 200=20 rpm difference to get the same air mass flow.
Very=20 interesting.

Thanks for=20 sharing.

Ed
All dyno runs, must be corrected to sea level standard day, so = that there=20 will be some usable data day to day to account for temperature, = humidity, and=20 barometric pressure. Actual HP goes up and down with changes in all of = these=20 factors. Raw torque numbers are meaningless until corrected as = above.=20
 
Like the RPM drop when you check the carb heat. And the reason = you lean=20 the mixture as you climb.
 
On a Southwest 737 we landed at the old Denver, and before we = pushed back=20 with full fuel and seats, the ticket agent got on the PA and asked for = 6=20 people to volunteer to get off and catch the next plane, because now = the plane=20 was too heavy to legally leave Denver. Because it was 102 degrees = outside.=20
 
The wife and I held out for a round trip each to anywhere in the = system.=20 On the way off the plane, we were handed a magnum of champagne. We = went to the=20 ticket counter, then to the very next gate, and got on a plane that = was a=20 nonstop to Columbus Ohio. There were 12 people on that plane. The = plane we got=20 off of landed in Chicago and got stuck there for three hours in = thunder=20 storms. 
 
Life is good.
 
Lynn E. Hanover
 
 
Yes, apples to apples comparisons requires keeping = accurate=20 track of all those varibles - especially if you want to determine = if=20 changes you made actually produced and improvement or just = atmosphere=20 conditions.
 
 By the way, Lynn, did the Champagne help the 3 hour layover = in=20 Chicago {:>)????
 
Ed
 
Ed



See what's new at AOL.com=20 and Make AOL Your=20 Homepage.
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