X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 16 Apr 2012 08:13:56 -0400 Message-ID: X-Original-Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTP id 5480980 for lml@lancaironline.net; Sat, 14 Apr 2012 02:48:42 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=dfs155@roadrunner.com X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=Hvb06jvS c=1 sm=0 a=9LmAXEz63j2NgFYNcmwa5A==:17 a=Z9DVfGi6iZUA:10 a=zTVDa7HKqxcA:10 a=8nJEP1OIZ-IA:10 a=pvbXhe53V58VLN98PHAA:9 a=QrpnLrtGiah4D5ZmjS0A:7 a=wPNLvfGTeEIA:10 a=9LmAXEz63j2NgFYNcmwa5A==:117 X-Cloudmark-Score: 0 X-Originating-IP: 76.178.22.154 Received: from [76.178.22.154] ([76.178.22.154:3162] helo=dan) by cdptpa-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 31/3E-16302-6AD198F4; Sat, 14 Apr 2012 06:48:06 +0000 X-Original-Message-ID: <7D8FC67C507E41CE8C3CE12A7924C107@dan> From: "Dan Schaefer" X-Original-To: "Lancair list" Subject: L320 flap setting X-Original-Date: Fri, 13 Apr 2012 23:47:57 -0700 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 To answer Ed Gray's question about "why reflex"? Ed, regarding your question about the aerodynamic reasons for reflexed flaps. The 235, 320 and 360 (not sure about the LNC4 or Legacy) all sport an airfoil utilizing "natural laminar flow" (NLF) that, under most conditions, have very good low-drag performance. Unfortunately, as usual, you can't get something for nothing and what you pay for the low-drag aerodynamics is a higher than normal pitching moment, e.g., the wing wants to pitch nose-down. As the airplane goes faster, the the nose-down pitching force increases requiring more nose-up trim. As a result, trim drag increases and the airplane bogs down, speed-wise. A secondary effect is imposition of a high twisting load on the wing structure which, according to Lance N. back in the day, is not a good thing. Reflexing the flaps counters much of the high pitching moment (noticeable by a decided pitch-up when you go to reflex) requiring a bunch of down-trim to maintain level flight. This has the effect of reducing the high trim drag and further, reduces the twisting stresses in the wing structure. Even though you trim to level flight, it's like pushing the nose down with the resulting increase in airspeed. Though I can certainly verify the positive effect on airspeed when going to reflex I can't say much about the reduction in wing stresses - just that, back in the day when I built my early 235, it was made very clear by the factory that the wing should always be in reflex at and above 160 IAS. Hope this helps. Dan Schaefer Early LNC2 N235SP - still a fun lawn dart flying since 1993.