X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 08 Jun 2009 13:00:03 -0400 Message-ID: X-Original-Return-Path: Received: from nschwmtas02p.mx.bigpond.com ([61.9.189.140] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3675192 for lml@lancaironline.net; Mon, 08 Jun 2009 07:07:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=61.9.189.140; envelope-from=frederickmoreno@bigpond.com Received: from nschwotgx02p.mx.bigpond.com ([124.178.53.195]) by nschwmtas02p.mx.bigpond.com with ESMTP id <20090608110634.QMLF1863.nschwmtas02p.mx.bigpond.com@nschwotgx02p.mx.bigpond.com> for ; Mon, 8 Jun 2009 11:06:34 +0000 Received: from Razzle ([124.178.53.195]) by nschwotgx02p.mx.bigpond.com with ESMTP id <20090608110633.LQFL11262.nschwotgx02p.mx.bigpond.com@Razzle> for ; Mon, 8 Jun 2009 11:06:33 +0000 From: "Frederick Moreno" X-Original-To: "Lancair Mail" Subject: FW: [LML] Re: L360 winglets X-Original-Date: Mon, 8 Jun 2009 19:06:27 +0800 X-Original-Message-ID: <4721B5E739984A018B8A86D6D9D2E61C@Razzle> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00A8_01C9E86C.3A3391E0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6838 Thread-Index: AcnoIEVESU9Pv0+MQVif+xnTAIjJfQAB5nJA X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Importance: Normal X-RPD-ScanID: Class unknown; VirusThreatLevel unknown, RefID str=0001.0A150205.4A2CF0BA.0031,ss=1,fgs=0 X-SIH-MSG-ID: qRAwENX6TFa2kTAvmTy2alorgFm6/gF5uMhSBI0wt0lHEVbCu8XAQs2rbaZC34/v0S4xaUSVRCR+c7zsTY7QuNm2K79VSrLZ5/E2 This is a multi-part message in MIME format. ------=_NextPart_000_00A8_01C9E86C.3A3391E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable "There is absolutely no question that winglets work if properly designed = and correctly installed." =20 =20 It depends on what you mean by "winglets work." =20 Winglets can reduce induced drag at the expense of an increase in = parasitic (friction) drag arising from more surface area exposed to the flow. The result is a net decrease in drag if you fly with a lift coefficient = greater than about 0.5-0.6. That corresponds to high angles of attack. In airliners, it means travelling heavily loaded up high in thin air where = the airplane is mushing along. =20 Since we fly our airplanes in regimes where the lift coefficient is more like 0.2-0.3 (in thick air going comparatively fast), the reduction in induced drag is slight while the increase in parasitic drag is more than slight, and consequently the airplane goes slower.=20 =20 If you want to fly your Lancair slowly like a glider near it's best lift/drag speed (about 135 knots IAS in a Lancair IV), there will be measurable performance benefit with winglets. =20 =20 As you go faster, the drag reduction benefits of winglets decline and = become negative as you approach cruise speeds.=20 =20 As for appearance, ah, that is a subjective, not quantitative, = assessment.=20 =20 Wingless Fred ------=_NextPart_000_00A8_01C9E86C.3A3391E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

“There is absolutely no question that winglets = work if properly designed and correctly = installed.”  

 

It depends on what you mean by “winglets = work.”

 

Winglets can reduce induced drag at the expense of an increase in parasitic (friction) drag arising from more surface area = exposed to the flow.  The result is a net decrease in drag if you fly with a = lift coefficient greater than about 0.5-0.6.  That corresponds to high = angles of attack.   In airliners, it means travelling heavily  = loaded up high in thin air where the airplane is mushing = along.

 

Since we fly our airplanes in regimes where the lift = coefficient is more like 0.2-0.3 (in thick air going comparatively fast), the = reduction in induced drag is slight while the increase in parasitic drag is more than slight, = and consequently the airplane goes slower.

 

If you want to fly your Lancair slowly like a glider near it’s best = lift/drag speed (about 135 knots IAS in a Lancair IV), there will be measurable performance = benefit with winglets. 

 

As you go faster, the drag reduction benefits of = winglets decline and become negative as you approach cruise speeds.

 

As for appearance, ah, that is a subjective, not quantitative, assessment.

 

Wingless Fred

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