Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2883491 for flyrotary@lancaironline.net; Tue, 09 Dec 2003 11:19:32 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hB9GJQxk006111 for ; Tue, 9 Dec 2003 11:19:29 -0500 (EST) Message-ID: <001201c3be6f$babe8040$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Air Density at altitude Date: Tue, 9 Dec 2003 11:15:56 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01C3BE45.D0D44920" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_000F_01C3BE45.D0D44920 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable ----- Original Message -----=20 From: Jim Sower=20 To: Rotary motors in aircraft=20 Sent: Tuesday, December 09, 2003 12:46 AM Subject: [FlyRotary] Re: Air Density at altitude Turbos will indeed complicate some shit.=20 Eric Ruttan wrote:=20 Ah yes. But I was thinking of a turbo engine making full power up = to 25K. Which of course destroys the symmetry of the math. So I = restate. If at X mpg IAS at 2000' you can get rid of Y BTU heat Then can = you get rid of Y BTU heat at X mph IAS at 25K' If IAS is a direct = measurement of Air Mass then yes, as the Air Mass is the same. If not = then IAS is not a direct measurement of Air Mass. Or my logic is faulty. = Thanks for your tolerant indulgence. Jim, both my calculations (after correcting the error that Bill = pointed out) and Bill's calculations show that indicated air speed is = not a good indiction of mass flow. Identical indicated airspeeds = between sea level and 20,000 ft would have a 30% lower mass flow at = 20,000 ft than at sea level. =20 That does not mean you would necessairly have any cooling problem = provided you only needed to get rid of approx 70% of the heat you did at = sea level (i.e reduced power out put - but, if using a turbo then if it = were marginal cooling at sea level, I think you would have problems at = 20,000 even with the cooler air. =20 FWIW Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ------=_NextPart_000_000F_01C3BE45.D0D44920 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

----- = Original Message=20 -----

From:=20 Jim=20 Sower
To: Rotary motors in = aircraft

Sent: Tuesday, December 09, = 2003 12:46=20 AM

Subject: [FlyRotary] Re: Air = Density at=20 altitude

Turbos will indeed complicate some shit.=20
Eric Ruttan wrote:=20

Ah yes. But I was thinking = of a turbo=20 engine making full power up to 25K. Which of course destroys = the=20 symmetry of the math. So I=20 restate. If at = X mpg IAS=20 at 2000' you can get rid of Y BTU heat Then can you get rid of Y BTU heat at X = mph IAS at=20 25K' If IAS is = a direct=20 measurement of Air Mass then yes, as the Air Mass is the=20 same. If not = then IAS is=20 not a direct measurement of Air Mass. Or my logic is = faulty. Thanks for your tolerant=20 indulgence.

Jim, both my calculations (after = correcting the=20 error that Bill pointed out) and Bill's calculations show that = indicated air=20 speed is not a good indiction of mass flow. Identical = indicated=20 airspeeds between sea level and 20,000 ft would have a 30% lower = mass flow=20 at 20,000 ft than at sea level.

That does not mean you would = necessairly have=20 any cooling problem provided you only needed to get rid of approx = 70% of the=20 heat you did at sea level (i.e reduced power out put - but, if using = a turbo=20 then if it were marginal cooling at sea level, I think you would = have=20 problems at 20,000 even with the cooler air.

FWIW

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, = NC
eanderson@carolina.rr.com

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