Return-Path: Received: from mail.cruzio.com ([208.226.92.37]) by truman.olsusa.com (Post.Office MTA v3.1.2 release (PO203-101c) ID# 0-44819U2500L250S0) with ESMTP id AAA7476 for ; Tue, 22 Sep 1998 03:06:38 -0400 Received: from testelectronics.mail (sa-207-251-8-165.cruzio.com [207.251.8.165]) by mail.cruzio.com with SMTP id AAA14434 for ; Tue, 22 Sep 1998 00:06:33 -0700 (PDT) Received: from main [192.168.1.1] by testelectronics.mail [192.168.1.1] with SMTP (MDaemon.v2.5.rB.b2.32-R) for ; Tue, 22 Sep 98 00:03:53 -0700 Received: by localhost with Microsoft MAPI; Tue, 22 Sep 1998 00:03:53 -0700 Message-ID: <01BDE5BC.7BF26F20.ed@testelectronics.com> From: Ed Armstrong Reply-To: "ed@testelectronics.com" To: "Lancair [Lancair.List@Olsusa.Com] (E-mail)" Subject: How hard can you land? Date: Tue, 22 Sep 1998 00:03:52 -0700 Organization: Test Electronics X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Thank you Brent for pointing me in the right direction. Brent helped me solve the question "how hard can you land?". After sifting through CFR 23.471 through 23.511 for landing gear load requirements. I found the one simple rule of thumb solution Sec. 23.473 Ground load conditions and assumptions. (e) Wing lift not exceeding two-thirds of the weight of the airplane may be assumed to exist throughout the landing impact and to act through the center of gravity. The ground reaction load factor may be equal to the inertia load factor minus the ratio of the above assumed wing lift to the airplane weight. To put this simply, the wing lift of two-thirds of the weight of the airplane gives me 1123 pounds of extra weight in addition to the 100lbs I originally used. The maximum specified landing weight is 1685, The maximum taxi weight is 1785. When landing we can say that the wings will hold off 2/3*1685=1123 lbs. at impact. So, we have the 100 lbs plus 1123 lbs to impact with. The resulting "G" force of landing impact should allow us the taxi weight of 1785 plus the weight the wings are holding off 1123 which equals 2908 lbs. The maximum allowed landing G forces would then be this weight 2908 lbs divided by the landing weight 1685 lbs which equals 1.73 G's. That is a fairly hard landing, a landing you would really feel! It eases my mind to know that my original idea that the landing force would only be 1.06 G's to make 1685 lbs go up to 1785 lbs. Is really 1.73 G's to make 1685 go up to 2908 lbs because the wings are holding off 1123 lbs.. Happy Landings Ed L360 Watsonville CA