<DIV style="font-family:Arial,sans-serif;">Yeah a scoop exit like the p-51 had. I bet we could invent the next must have pattern thingy. Tempature controled movable cooling scoops.<BR><BR>Randy<BR><BR>--- d.pappas@kodeos.com wrote:<BR><BR>From: "Dean Pappas" <d.pappas@kodeos.com><BR>To: "NSRCA Mailing List" <nsrca-discussion@lists.nsrca.org><BR>Subject: Re: [NSRCA-discussion] cooling area<BR>Date: Tue, 5 Dec 2006 10:19:05 -0500<BR><BR>
<DIV><SPAN><FONT face="Arial" size="2">Hi
All,</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">I'll go one step
further: measuring the exit area by looking at the bottom of the airplane is
wrong. Do you want the air shooting vertically out the bottom of the ship? Of
course not.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">The expansion of air
in our cooling setups is practically negligible. Let's say that the air heats up
a whole 100 degrees F as it goes through the system. There is no way that
it heats up even half of that. On a normal day, the air is at at roughly
535 degrees absolute, so a 100 degree warmup will make the air expand less than
10%.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2"></FONT></SPAN> </DIV>
<DIV><SPAN><FONT face="Arial" size="2">If you take a square
inch of air into the front of the airplane at 80 MPH, you want 1.1 square inches
of exit ... as viewed from directly behind the aircraft!</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">Now if you cut a
hole in the bottom of the plane, you have to ask how the air is coming out. Is
the hole really aft of the fuselage bottom "high point"?</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">Is it really on the
flat bottom? Then air is going to exit the plane at some shallow angle, and the
effective area is going to be much smaller than what you see looking at the
bottom of the plane.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">Unless the exit hole
is huge, this means that the system is outlet choked, when flying at speed, and
adding drag to boot.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2"></FONT></SPAN> </DIV>
<DIV><SPAN><FONT face="Arial" size="2">We really should
build aft-facing exit scoops like some older Pattern designs, or the slick
trick used on the aft end of the belly pan of the Zeque.</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">Later,</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2">Dean</FONT></SPAN></DIV>
<DIV><SPAN><FONT face="Arial" size="2"></FONT></SPAN> </DIV>
<P>.</P>
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