Return-Path: Received: from imo15.mx.aol.com ([198.81.17.5]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with ESMTP id com for ; Tue, 25 May 1999 12:19:45 -0400 Received: from Fredmoreno@aol.com (8058) by imo15.mx.aol.com (IMOv20) id kOTZa02575 for ; Tue, 25 May 1999 12:20:50 -0400 (EDT) From: Fredmoreno@aol.com Message-ID: Date: Tue, 25 May 1999 12:20:50 EDT Subject: IV Nose Gear Door Failure To: lancair.list@olsusa.com X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Some close inspection of photos of IVs in flight has disclosed that gear doors that are tight on the ground hang open a bit in the air due to internal air pressure in the lower cowl. Brent Regan and I lost a section of the gear door on his IV when racing. The forward 3 inches or so of one side was just gone (as in disappeared) when we arrived. Not much room for reinforcement, but I also believe that you need to spring the door so that is well loaded when closed and the plane is not moving to be reasonably sure it stays closed in flight. Internal pressures can be as high as 0.5-0.7 psi on a high speed descent (250 KIAS yields about 1.4 psi ram pressure, and about half remains at the bottom of the cowl in highest speed flight) . Apply that load to your door and see how much it deflects. I have been told that when setting rivets, one can put in a dab of epoxy and get a tighter, more vibration resistant structure, but this is annecdotal only. Fred Moreno >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML homepage: http://www.olsusa.com/Users/Mkaye/maillist.html