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From: "Eric Ruttan" <ericruttan@chartermi.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2881842@logan.com>
Subject: Re: [FlyRotary] Re: Air Density at altitude
Date: Mon, 8 Dec 2003 13:15:35 -0500
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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=20
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.
----- Original Message -----=20
From: Jim Sower=20
To: Rotary motors in aircraft=20
Sent: Monday, December 08, 2003 11:25 AM
Subject: [FlyRotary] Re: Air Density at altitude
But of course, with only 47% of air mass flow through the radiator, =
you also have only 47% of air mass flow through the engine and 47% as =
much heat to reject. So, for an NA engine, there shouldn't be a =
significant change in the ability of a cooling system.=20
Or so it seems to me .... Jim S.=20
Ed Anderson wrote:=20
Found a table of air density vs Altitude=20
Sea level Density =3D .00237 Slug/Ft^3=20
Density at 20,000 =3D 0.001267 Slug/Ft^3 or a 47% decrease=20
So taking formula for air mass W =3D p*V*A with p 47% less than at =
sea level=20
means you would get 47% less air mass flow (with the same cubic =
feet/minute=20
of air volume flow) at 20,000 ft compared to what you would get at =
sea level=20
for the same volume flow.=20
While cooler temps would help, it would not compensate for a 45% =
less air=20
mass flow.=20
Ed=20
Ed Anderson=20
RV-6A N494BW Rotary Powered=20
Matthews, NC=20
eanderson@carolina.rr.com=20
>> Homepage: http://www.flyrotary.com/=20
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
--=20
Jim Sower=20
Crossville, TN; Chapter 5=20
Long-EZ N83RT, Velocity N4095T=20
=20
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<DIV><FONT face=3DArial size=3D2>Ah yes. But I was thinking of a =
turbo engine=20
making full power up to 25K. Which of course destroys the symmetry =
of the=20
math.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>So I restate.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>If at X mpg IAS at 2000' you can =
get rid of Y=20
BTU heat </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Then c</FONT><FONT face=3DArial =
size=3D2>an you get rid=20
of Y BTU heat at X mph IAS at 25K'</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>If IAS is a direct measurement of Air =
Mass then=20
yes, as the Air Mass is the same.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>If not then IAS is not a direct =
measurement of Air=20
Mass.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Or my logic is faulty.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks for your <SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial; mso-fareast-font-family: =
'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: =
EN-US; mso-bidi-language: AR-SA">tolerant=20
indulgence</SPAN>.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dcanarder@frontiernet.net =
href=3D"mailto:canarder@frontiernet.net">Jim=20
Sower</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dflyrotary@lancaironline.net=20
href=3D"mailto:flyrotary@lancaironline.net">Rotary motors in =
aircraft</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, December 08, 2003 =
11:25=20
AM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [FlyRotary] Re: Air =
Density at=20
altitude</DIV>
<DIV><BR></DIV>But of course, with only 47% of air mass flow through =
the=20
radiator, you also have only 47% of air mass flow through the =
<B>engine</B>=20
and 47% as much heat to reject. So, for an NA engine, there =
shouldn't be=20
a significant change in the ability of a cooling system. <BR>Or so it =
seems to=20
me .... Jim S.=20
<P>Ed Anderson wrote:=20
<BLOCKQUOTE TYPE=3D"CITE">Found a table of air density vs Altitude=20
<P>Sea level Density =3D .00237 Slug/Ft^3 <BR>Density at 20,000 =3D =
0.001267=20
Slug/Ft^3 or a 47% decrease=20
<P>So taking formula for air mass W =3D p*V*A with p 47% less =
than at=20
sea level <BR>means you would get 47% less air mass flow (with the =
same=20
cubic feet/minute <BR>of air volume flow) at 20,000 ft compared to =
what you=20
would get at sea level <BR>for the same volume flow.=20
<P>While cooler temps would help, it would not compensate for a 45% =
less air=20
<BR>mass flow.=20
<P>Ed=20
<P>Ed Anderson <BR>RV-6A N494BW Rotary Powered <BR>Matthews, NC=20
<BR>eanderson@carolina.rr.com=20
<P>>> Homepage: <A=20
href=3D"http://www.flyrotary.com/">http://www.flyrotary.com/</A>=20
<BR>>> Archive: <A=20
=
href=3D"http://lancaironline.net/lists/flyrotary/List.html">http://lancai=
ronline.net/lists/flyrotary/List.html</A></P></BLOCKQUOTE>
<P>-- <BR>Jim Sower <BR>Crossville, TN; Chapter 5 <BR>Long-EZ N83RT, =
Velocity=20
N4095T <BR> </P></BLOCKQUOTE></BODY></HTML>
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