X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 12 Aug 2007 00:26:03 -0400 Message-ID: X-Original-Return-Path: Received: from mta19.adelphia.net ([68.168.78.226] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2256712 for lml@lancaironline.net; Sat, 11 Aug 2007 13:19:30 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.226; 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 <20070811141315.SZWF28634.mta9.adelphia.net@[75.82.253.35]> for ; Sat, 11 Aug 2007 10:13:15 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) X-Original-To: Lancair List X-Original-Message-Id: Content-Type: multipart/alternative; boundary=Apple-Mail-9-228480924 From: Gary Casey Subject: Re: Forced landing X-Original-Date: Sat, 11 Aug 2007 07:13:14 -0700 X-Mailer: Apple Mail (2.752.2) --Apple-Mail-9-228480924 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Just in case you want to worry even more about off-airport approach speeds, the people that earn their keep designing crash protection in cars tell me that crash "severity" is roughly proportional to the CUBE of speed, not the square. Crash mathematics is a messy thing, but think of it as requiring the energy to be absorbed in the same distance, not time. Double the speed and you halve the time available to absorb 4 times the energy. Going from 80kts to 100 is then almost twice as "severe." Gary Casey yeah, I think about that 20 extra knots a lot. Unfortunately energy increases with the square of speed. For any given vehicle a groundspeed of 100 KTS means a little over 50% more energy than a groundspeed of 80 KTS. In other words it requires over 50% more distance to stop if the brakes are applied at 100 KTS as it does at 80 KTS. Stopping from 60 mph requries 4x the distance as compared to stopping from 30 mph, under identical conditions and not including the distance used during reaction time. Aren't you glad you asked? Tom Gourley --Apple-Mail-9-228480924 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1
Just in case = you want to worry even more about off-airport approach speeds, the = people that earn their keep designing crash protection in cars tell me = that crash "severity" is roughly proportional to the CUBE of speed, not = the square.=A0 Crash mathematics is a messy thing, but think of it as = requiring the energy to be absorbed in the same distance, not time.=A0 = Double the speed and you halve the time available to absorb 4 times the = energy.=A0 Going from 80kts to 100 is then almost twice as = "severe."
Gary Casey

yeah, I think about that 20 extra knots a = lot.

=A0

Unfortunately energy increases with the = square of speed.=A0 For any given=A0vehicle a groundspeed of 100 KTS = means a little over 50% more energy than a groundspeed of 80 KTS.=A0 In = other words it requires over 50% more distance to stop if the brakes are = applied at 100 KTS as it does at 80 KTS.=A0 Stopping from=A060 mph = requries=A04x=A0the distance=A0as=A0compared to stopping=A0from 30 mph, = under identical conditions and not including the distance used during = reaction time.

=A0

Aren't you glad you = asked?

=A0

Tom Gourley= --Apple-Mail-9-228480924--