X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Fri, 24 Nov 2006 15:13:55 -0500 Message-ID: X-Original-Return-Path: Received: from smtp101.sbc.mail.mud.yahoo.com ([68.142.198.200] verified) by logan.com (CommuniGate Pro SMTP 5.1.2) with SMTP id 1599482 for lml@lancaironline.net; Fri, 24 Nov 2006 13:21:59 -0500 Received-SPF: none receiver=logan.com; client-ip=68.142.198.200; envelope-from=elippse@sbcglobal.net Received: (qmail 88724 invoked from network); 24 Nov 2006 18:21:35 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=sbcglobal.net; h=Received:X-YMail-OSG:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE; b=ZpA/6hn/Gg26aYR5kwCNbnKWVwr9AiQVGRwWoetPCQjGVMCv2QqKzcnFpPyLxJW4aLup7O323vBiJ7FKKE2WhsWaQAPk8t2SikA7/2QCb5MKZ1d4sITaWdM9KuyKHjuhR1dEBskokNFw5wKDYGIKdAz96d1APwrGoimsM/7zCzU= ; Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@75.15.147.169 with login) by smtp101.sbc.mail.mud.yahoo.com with SMTP; 24 Nov 2006 18:21:34 -0000 X-YMail-OSG: PbvqeMUVM1kFaR_Ptm3kQwRBS4TX1INDTwcZtF.ZZjbMzx2bQyQ1g5F0UocvWBKDM9wmG008wVz9kIF1TkZRnzls.TXbaq.8Nci3x_ILhEet7PltqIB4ow-- X-Original-Message-ID: <000901c70ff5$62a43000$a9930f4b@Computerroom> From: "Paul Lipps" X-Original-To: "Marv Kaye" Subject: Control surface shape, nav ant. X-Original-Date: Fri, 24 Nov 2006 10:21:38 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C70FB2.5362D5D0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C70FB2.5362D5D0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable There are two things you can do to the control surface shape that = will both reduce drag and reduce flutter tendency. 1. Increase the = leading edge thickness by 15% of the leading-surface TE, on each side, = with a rounded shape. 2. Give the top and bottom surfaces a convex = shape. Doing (1) can lead to the creation of the (2) shape. The larger = shape ahead of the leading-surface TE does two things. It provides = Coanda-effect to turn air flow through the gap around toward the rear, = and reattaches the flow coming from the leading surface. This can result = in a drag decrease of about 20% locally, so that it is the same as with = no control surface break. Ref: "The Design of the Aeroplane", Darrol = Stinton, p.444. Scott: The nav antenna is given a slight sweep-back in order to fill = in the null along the array axis; remember the donut shape with a null = out to each side along the hole axis. And yes, Matt, that could be = destructive interference. But keep in mind that the destructive signals = could come from bad connections or leaky coax just as well as = re-radiation. If you didn't make the coax, I would definitely look at = your whole transmission line scheme as my experience is that builders = show incredible building talents but are often electrically-challenged = when it comes to wiring. The VSWR box is your friend there. I have = written in the past about the semi-rigid coax available from Andrew. It = is an item well worth the cost when thou$and$ are spent for avionics = which then don't get good signals. Every link in the chain is important. ------=_NextPart_000_0006_01C70FB2.5362D5D0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

There are two things you can = do to the=20 control surface shape that will both reduce drag and reduce flutter = tendency. 1.=20 Increase the leading edge thickness by 15% of the leading-surface TE, on = each=20 side, with a rounded shape. 2. Give the top and bottom surfaces a convex = shape.=20 Doing (1) can lead to the creation of the (2) shape. The = larger shape=20 ahead of the leading-surface TE does two things. It provides = Coanda-effect to=20 turn air flow through the gap around toward the rear, and reattaches the = flow=20 coming from the leading surface. This can result in a drag decrease of = about 20%=20 locally, so that it is the same as with no control surface = break. Ref: "The=20 Design of the Aeroplane", Darrol Stinton, p.444.

Scott: The nav antenna is = given a=20 slight sweep-back in order to fill in the null along the array axis; = remember=20 the donut shape with a null out to each side along the hole axis. And = yes, Matt,=20 that could be destructive interference. But keep in mind that the = destructive=20 signals could come from bad connections or leaky coax just as well as=20 re-radiation. If you didn't make the coax, I would definitely look at = your whole=20 transmission line scheme as my experience is that builders show = incredible=20 building talents but are often electrically-challenged when it comes to = wiring.=20 The VSWR box is your friend there. I have written in the past about the=20 semi-rigid coax available from Andrew. It is an item well worth the cost = when=20 thou$and$ are spent for avionics which then don't get good signals. = Every link=20 in the chain is important.

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