Return-Path: Received: from impulse.net (mail.impulse.net [204.188.6.10]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with SMTP id com for ; Thu, 14 Jan 1999 12:46:54 -0500 Received: (qmail 20891 invoked by alias); 14 Jan 1999 17:48:18 -0000 Received: from lo2-66.impulse.net (HELO impulse.net) (204.182.12.66) by mail.impulse.net with SMTP; 14 Jan 1999 17:48:18 -0000 Message-ID: <369E2D80.C46A3A49@impulse.net> Date: Thu, 14 Jan 1999 09:46:40 -0800 From: Karl Gallagher & Laura Rowanoak Reply-To: info@rocketplane.com To: lancair.list@olsusa.com Subject: Flutter Modification X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> I'm about to incorporate the flutter modification described by Martin Hollmann, as modified by Dave Morss. I'm going to fill the 3 inch wide "trough" in the fuselage tailcone formed by the joggle between left and right halves with 13 BID. I'm posting this because I want to make sure I have the proper fiber orientation. Martin's mod includes three BID layers (18" wide, 12" wide and 8" wide). This was intended to be an external modification to a finished airplane, so he wanted a thin layup. Since I want to put it on the inside, in the trough, I took the total amount of fiber (18 + 12 + 3 = 33) and figured 13 layers 2.5" wide would be equivalent (13 * 2.5 = 32.5 -- close enough). I called Martin who said "it should work, but the analysis wasn't done that way so I can't officially endorse it". Between his statement that "it should work", Dave Morss' "I did it that way" and Lance's opinion that "you don't need it anyways" I figure I'm covered. The Hollmann documentation states that "the fiberglass should be oriented at zero degrees to the longitudinal axis of the fuselage" which to me means the fibers are fore-aft-left-right. The sketch suggests that the main axis of the BID is this way, with half the fibers 45 degrees to the longitudinal axis and the other half 45 degrees the other way. (i.e. take a standard 45 x 45 BID and line it up nose to tail). This makes more sense to me since I don't think the fibers would stiffen torsionally if the actual fibers were fore-aft-left-right. I'm confused. Do the fibers go fore-aft-left-right or at 45 degrees to the aircraft axes? By the way, I asked Martin about breaking it into two layups, one forward of and one aft of the baggage bulkhead. (I have a fast build kit with the bulkhead already installed.) He said that would be fine. - Rob Wolf rwolf99@aol.com [I used a work e-mail address. Don't reply there or I won't get it. rwolf99@aol.com is the proper return address]