Return-Path: Received: from qmail.accesscomm.ca ([204.83.142.82] verified) by logan.com (CommuniGate Pro SMTP 4.1.5) with SMTP id 2637781 for flyrotary@lancaironline.net; Wed, 15 Oct 2003 11:08:18 -0400 Received: (qmail 18190 invoked from network); 15 Oct 2003 15:08:18 -0000 Received: from cust140-67.weyburn-leg.accesscomm.ca (HELO Jarrett) (216.174.140.67) by qmail.accesscomm.ca with SMTP; 15 Oct 2003 15:08:18 -0000 Message-ID: <00cb01c3932d$b53d7120$8200a8c0@Jarrett> From: "JJ JOHNSON" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: rooster-tail drag Date: Wed, 15 Oct 2003 09:04:59 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00C8_01C392FB.690E0940" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_00C8_01C392FB.690E0940 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable What is roster tail drag? how and where does it get created? Is there = anything about that written up on the net?I'd like to know since I'm in = the process of figuring out where to put my radiators in the Long = EZ.ThanksMarko Marko, Think of rooster tail drag as drag that's created when air leaves = the cowl at steep angle. The air, instead of turning and moving along = the side of the cowl like you'd think it would, shoots straight out from = the cowl for a small distance [ 6" may seem small but it will create a = huge drag penalty!] Another way to think of it is when your driving and = you throw that apple core out the window, notice how it goes straight = out for a little bit and then the on-coming air slows it down and it = 'appears' to go back.. Air leaving the cowl of your plane will follow = basically the same sort of path. So if we smooth this exit we'll find = that we reduce drag. Its one of the reasons that NACA ducts are soooo = popular, they create a very smooth exit [ the air is coming out parallel = to the side of the cowl and then as the duct narrows it is accelerated = and gradually pushed out into the normal airstream. So simple yet it = took years to understand it all. My 2 cents Jarrett Johnson ------=_NextPart_000_00C8_01C392FB.690E0940 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 What is roster tail drag? how and where = does it get=20 created? Is there anything about that written up on the=20 net?I'd like to know = since I'm in the=20 process of figuring out where to put my radiators in the Long=20 EZ.ThanksMarko
 
 
Marko,=20 Think of rooster tail drag as drag that's created when air leaves the = cowl at=20 steep angle. The air, instead of turning and moving along the side of = the cowl=20 like you'd think it would, shoots straight out from the cowl for a small = distance [ 6"  may seem small but it will create a huge drag = penalty!]=20 Another way to think of it is when your driving and you throw that apple = core=20 out the window, notice how it goes straight out for a little bit and = then the=20 on-coming air slows it down and it 'appears' to go back.. Air leaving = the cowl=20 of your plane will follow basically the same sort of path. So if we = smooth this=20 exit we'll find that we reduce drag. Its one of the reasons that NACA = ducts are=20 soooo  popular, they create a very smooth exit [ the air is coming = out=20 parallel to the side of the cowl and then as the duct narrows it is = accelerated and gradually pushed out into the normal airstream. So = simple yet it=20 took years to understand it all.
 
My 2=20 cents
Jarrett Johnson
 
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