X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ispmxmta06-srv.alltel.net ([166.102.165.167] verified) by logan.com (CommuniGate Pro SMTP 5.0.4) with ESMTP id 882615 for flyrotary@lancaironline.net; Wed, 14 Dec 2005 20:18:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=166.102.165.167; envelope-from=montyr2157@alltel.net Received: from Thorstwin ([4.89.244.20]) by ispmxmta06-srv.alltel.net with SMTP id <20051215011719.COQF3660.ispmxmta06-srv.alltel.net@Thorstwin> for ; Wed, 14 Dec 2005 19:17:19 -0600 Message-ID: <000501c60115$4d4b7690$14f45904@Thorstwin> From: "Monty Roberts" To: Subject: Cowl Exit Date: Wed, 14 Dec 2005 19:17:21 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0002_01C600E3.01F70560" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0002_01C600E3.01F70560 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Monty Monty, you are rebel!! Bottom posting it is, ....at least on this thread! Back to square 1!! We had a similar thread back in April! ROT's about exit/intake ratio where exit HAS to be bigger are gospel. If = you want to reduce cooling drag, read up on the following: (I am cheap enough to just copy my past posts and replies here:)) Not sure I follow you about exit larger than inlet being gospel. IF you = mean subject to translation errors and the cumulative alterations of = many scribes I might see your point. Everybody going fast has smaller = exits than inlets.=20 As I stated that is because the inlet must be sized for WOT climb where = you are moving a lot of air. At that point the outlet must be larger as = well like 150% to draw the air through and allow for expansion. OR you = must use an exhaust augmenter-take your pick. As the speed increases and the power level drops in cruise you need to = close the outlet down (unless you want a large drag penalty). Ideally = you should close the inlet down as well. Since it really doesn't matter = much on a Tractor (because of external diffusion and an ugly front end = aerodynamically anyway) and variable inlets are more complicated it does = not typically make sense to fool with closing the inlet down. So ideally you should have an inlet sized to cool the thing in climb, = followed by an exit that is variable from around 150%-70% or so = depending on how you plane to operate the aircraft. You want the minimum air flowing through the cooling system at any = cruise operating point to create the least drag. Unless you are in full = power climb, and then you just want to cool the thing. A single size for your outlet is a point design and will create excess = drag or inadequate cooling at other operating points.=20 Monty ------=_NextPart_000_0002_01C600E3.01F70560 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Monty
 
 
Monty, you are = rebel!!
Bottom posting it is, = ....at least on=20 this thread!
 
Back to square 1!!
 
We had a similar thread back in=20 April!
ROT's about exit/intake ratio = where exit HAS=20 to be bigger are gospel. If you want to reduce cooling drag, read up on = the=20 following:
(I am cheap enough to just copy = my past=20 posts and replies here:))
 
 
Not sure I follow you about exit larger than = inlet being=20 gospel. IF you mean subject to translation errors and the cumulative = alterations=20 of many scribes I might see your point. Everybody going fast has smaller = exits=20 than inlets.
 
As I stated that is because the inlet must be = sized for=20 WOT climb where you are moving a lot of air. At that point the outlet = must be=20 larger as well like 150% to draw the air through and allow for = expansion. OR you=20 must use an exhaust augmenter-take your pick.
 
As the speed increases and the power level drops = in cruise=20 you need to close the outlet down (unless you want a large drag = penalty).=20 Ideally you should close the inlet down as well. Since it really doesn't = matter=20 much on a Tractor (because of external diffusion and an ugly front end=20 aerodynamically anyway) and variable inlets are more complicated it does = not=20 typically make sense to fool with closing the inlet = down.
 
So ideally you should have an inlet sized to = cool the=20 thing in climb, followed by an exit that is variable from around = 150%-70% or so=20 depending on how you plane to operate the aircraft.
 
You want the minimum air flowing through the = cooling=20 system at any cruise operating point to create the least drag. Unless = you are in=20 full power climb, and then you just want to cool the thing.
 
A single size for your outlet is a point design = and will=20 create excess drag or inadequate cooling at other operating points.=20
 
Monty
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