X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 06 Mar 2014 08:06:34 -0500 Message-ID: X-Original-Return-Path: Received: from nm22-vm5.access.bullet.mail.bf1.yahoo.com ([216.109.115.148] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6761964 for lml@lancaironline.net; Wed, 05 Mar 2014 21:42:33 -0500 Received-SPF: neutral receiver=logan.com; client-ip=216.109.115.148; envelope-from=browncc1@verizon.net Received: from [66.196.81.155] by nm22.access.bullet.mail.bf1.yahoo.com with NNFMP; 06 Mar 2014 02:41:59 -0000 Received: from [98.138.104.97] by tm1.access.bullet.mail.bf1.yahoo.com with NNFMP; 06 Mar 2014 02:41:58 -0000 Received: from [127.0.0.1] by smtp117.sbc.mail.ne1.yahoo.com with NNFMP; 06 Mar 2014 02:41:58 -0000 X-Yahoo-Newman-Id: 646401.38251.bm@smtp117.sbc.mail.ne1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: 4YvE6_EVM1n4ymBUErYHPH4JkMZ38jVPoQqZeoiFaY0KkOL 5FyFH6C_pbexHtHtMW8p58LHaI0AU_iqVqH1KWS38BcZy6IBiFR9tg98KOO2 ginlmmLxzaotrTqaCbNRIKawhZhKx_gDhzAng6r.UP4WDv_rh_HmWagZpKss Jf9w6eTlBC7oR2kzgTu3qrMzWU5LL2A5JYe1wYQ1Ebct8UaeDW8Qpcm5hArd gjcSBZYUtBMrazLBE.gIHsaUMkcmcASNezNcIKx5azyj_u9t1Yf4BzXjGjJd UOGnowiXRz81XK1SYqjYpwPQ0jZBpe662yYhLSd3Uy8Lb6L4m1JVDW6pXT17 jBY31EYBNrXgybTtSIoRjSWBO1Yf61hlyQgusDVwErpB5QddXlAODASx4PRD lVjNTJuK4LqfQUsH6OrKCutgRw4U3CCNHEyKW0ooUu8dukgOFpOhuWKu.VeD grrGribssXEUYRxJh8MEy_wxTgixA39yMydsdkvG260Tdq52.3IZ_ETmTxnm 3cakIb2R7U60gswCjRtWCgjGiP3ws_l6bwRsjgDycHIood3xcwVN47lfqlLK v5Xnjsw-- X-Yahoo-SMTP: F49l9g6swBC0R9n8vJIbm7Tf3P8Xlmia8rHIwTlO__Ml X-Rocket-Received: from chass-imac-2.home (browncc1@72.64.106.138 with plain [98.138.84.31]) by smtp117.sbc.mail.ne1.yahoo.com with SMTP; 06 Mar 2014 02:41:58 +0000 UTC From: Charles Brown Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: multipart/alternative; boundary=Apple-Mail-1--845310077 Subject: Re: [LML] Canopy Latch modeling X-Original-Date: Wed, 5 Mar 2014 20:41:57 -0600 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <7BEE61AF-913F-431A-AC26-A780E4BBB2E5@verizon.net> X-Mailer: Apple Mail (2.1085) --Apple-Mail-1--845310077 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii a) The canopy is generating lift when closed. More to your point, the = pressure on the inside of the canopy is higher than the pressure on the = outside. I'll assert that without citing several reasons why it's true. = Next, the canopy lift will decrease when it's unlatched; the canopy = will rise until the sum of the moments around its fwd hinge point are = equal. That is, it will rise until the delta P from bottom to top = decreases to *just enough* to offset its weight minus the gas strut = contribution. b) The cg moves forward trivially when the canopy opens all the way. If = the canopy weighs 50 lb, and it opens 90 degrees, a rough hack indicates = that the cg would move forward about 0.6 inches, or 7% of the total = allowable cg range. And the canopy won't open 90 degrees; at small = openings the cg change is completely negligible. c) The drag increase will be significant. If the canopy opens six = inches, then using a typical Cp for an aft-facing step of -0.1 and = assuming no change to the pressure on the upper surface (that means I'll = calculate a minimum value for the drag; the real drag will be greater), = you'll introduce a delta Cd of about .002. Cruise Cd is around .014 so = that's a drag increase of 15% -- at least -- for a 6" opening. d) Recent posts suggest keeping the angle of attack low. That makes = sense to me. Adding power makes sense to me; offsets the drag and keeps = alpha low. Takeoff flap makes sense to me; reduces fuselage alpha = without adding much drag. Charley From: Paul Miller Date: March 4, 2014 6:21:39 AM CST To: lml@lancaironline.net Subject: Re: [LML] Canopy Latch modeling Let me ask these questions to the group, speculation is permitted since = we have no data: a) is the canopy generating lift when closed? If so, does that lift = decrease or increase when unlatched? b) Does the CG of the aircraft change between open and closed canopy in = flight? c) Does drag increase between open and closed in flight? d) What does a pilot do when all that noise and flying paper occurs? = Full throttle, decrease power? Paul --Apple-Mail-1--845310077 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

d) Recent = posts suggest keeping the angle of attack low.  That makes sense to = me.  Adding power makes sense to me; offsets the drag and keeps = alpha low.  Takeoff flap makes sense to me; reduces fuselage alpha = without adding much = drag.

Charley


From: = Paul Miller <pjdmiller@gmail.com>
=
Date: = March 4, 2014 6:21:39 AM CST
Subject: = Re: [LML] Canopy Latch = modeling


Let me ask these questions to the = group, speculation is permitted since we have no data:

a) is the = canopy generating lift when closed? If so, does that lift decrease or = increase when unlatched?
b) Does the CG of the aircraft change = between open and closed canopy in flight?
c) Does drag increase = between open and closed in flight?
d) What does a pilot do when all = that noise and flying paper occurs?  Full throttle, decrease = power?

Paul


= --Apple-Mail-1--845310077--