Return-Path: Received: from mail.mc.net ([209.172.128.4]) by ns1.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-64832U3500L350S0V35) with SMTP id com for ; Thu, 4 Jan 2001 10:47:01 -0500 Received: (qmail 27756 invoked from network); 4 Jan 2001 15:55:16 -0000 Received: from chi-ras-1-209-112-95-104.mc.net (HELO mc.net) (209.112.95.104) by mail.mc.net with SMTP; 4 Jan 2001 15:55:16 -0000 Message-ID: <3A549DD1.FE5713AB@mc.net> Date: Thu, 04 Jan 2001 09:59:13 -0600 From: jerry@mc.net To: lancair.list@olsusa.com Subject: Re: Yaw oscillation References: X-Mailing-List: lancair.list@olsusa.com Reply-To: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Jim, I have given some thought to the yaw problem you so elegantly describe. There's one thing that could be looked at closely ... the possibility the vertical stab/rudder shape are acting like an airfoil to create horizontal lift (yaw). The process could be started by one side of the vertical having more airfoil shape than the other side, thereby producing enough lift to overcome the streamlining airflow. As the streamlining airflow overcomes the lift, the correcting force starts a recovery until the yaw cycle is complete. Additionally, if the rudder is out of balance, it could enhance the airfoil shape. It does this by creating more camber effect, thus, providing more lift to one side, and then to the other side, as the cycle completes. The rudder acts much like a flap on a wing and creates lift. Of course, if it's out of balance this "flap" would have a mind of it's own and would "hunt" for it's center position and, of course, never find it. If the left and right sides of the vertical ARE symmetrical, then the vertical may not be pointing straight down the road. I'd look at the airfoil symmetry, rigging of the vertical and the balance of the rudder. Jerry Grimmonpre' LNC2 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>