X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 13 Aug 2007 16:51:20 -0400 Message-ID: X-Original-Return-Path: Received: from mta9.adelphia.net ([68.168.78.199] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2259367 for lml@lancaironline.net; Mon, 13 Aug 2007 09:28:19 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.199; envelope-from=glcasey@adelphia.net Received: from [75.82.253.35] by mta9.adelphia.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20070813132738.JOQE28634.mta9.adelphia.net@[75.82.253.35]> for ; Mon, 13 Aug 2007 09:27:38 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-10-398544039 X-Original-Message-Id: <2BC68F45-B074-4052-A529-0340C7ED46B0@adelphia.net> From: Gary Casey Subject: Re: Forced landing X-Original-Date: Mon, 13 Aug 2007 06:27:37 -0700 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.752.2) --Apple-Mail-10-398544039 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes; format=flowed Kevin, You are correct - if the "stop" is at a constant deccel rate, whether =20= by braking on a runway or sliding across a field, the distance is =20 proportional to the square of the speed. However, if it is more of a =20= constant-distance thing the "severity" is roughly proportional to the =20= cube of the speed. Problem is, you don't don't know which condition =20 is governing until you get there. Even if you are sliding across a =20 field at twice the touchdown speed (I use the word "touch" loosely) =20 you have four times as many rocks that you could hit and each rock =20 could do that much more damage at the higher speed. Thinking of the =20 potential damage as a function of the speed cubed tends to add =20 emphasis to the approach speed control. If your plane stalls at =20 60kts, impacting the ground at 75, still below a normal approach =20 speed, can potentially double the severity compared to impacting at =20 the lowest possible speed. Gary > > Yeah, but isn=92t that if you hit a wall, another car, tree or slam =20= > into steep hill? Skidding across a field potentially gives more =20 > distance and time doesn=92t it (assuming we avoid ravines, ditches, =20= > and the barn doors=85)? > > > > Kevin --Apple-Mail-10-398544039 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=WINDOWS-1252 Kevin,

You are correct - if = the "stop" is at a constant deccel rate, whether by braking on a runway = or sliding across a field, the distance is proportional to the square of = the speed.=A0 However, if it is more of a constant-distance thing the = "severity" is roughly proportional to the cube of the speed.=A0 Problem = is, you don't don't know which condition is governing until you get = there.=A0 Even if you are sliding across a field at twice the touchdown = speed (I use the word "touch" loosely) you have four times as many rocks = that you could hit and each rock could do that much more damage at the = higher speed.=A0 Thinking of the potential damage as a function of the = speed cubed tends to add emphasis to the approach speed control.=A0 If = your plane stalls at 60kts, impacting the ground at 75, still below a = normal approach speed, can potentially double the severity compared to = impacting at the lowest possible speed.

Gary

=
Yeah, but isn=92t that if you hit a = wall, another car, tree or slam into steep hill?=A0 Skidding across a = field potentially gives more distance and time doesn=92t it (assuming we = avoid ravines, ditches, and the barn = doors=85)?
=A0
Kevin

= --Apple-Mail-10-398544039--