X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 12 Aug 2007 09:15:55 -0400 Message-ID: X-Original-Return-Path: Received: from [69.146.254.20] (HELO arilabs.net) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2257326 for lml@lancaironline.net; Sun, 12 Aug 2007 01:21:19 -0400 Received-SPF: none receiver=logan.com; client-ip=69.146.254.20; envelope-from=Kevin@arilabs.net Subject: RE: [LML] Re: Forced landing MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C7DCA0.85B5E771" X-Original-Date: Sat, 11 Aug 2007 23:20:10 -0600 Content-class: urn:content-classes:message X-MimeOLE: Produced By Microsoft Exchange V6.5 X-Original-Message-ID: <7141427652BB3049A7DBF1084B67805B0F81B7@penumbra.arilabs.net> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Re: Forced landing Thread-Index: AcfcmRMW62mKCNXVRdeg62jP2ST/UQABqvqw References: From: "Kevin Stallard" X-Original-To: "Lancair Mailing List" This is a multi-part message in MIME format. ------_=_NextPart_001_01C7DCA0.85B5E771 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Yeah, but isn't that if you hit a wall, another car, tree or slam into steep hill? Skidding across a field potentially gives more distance and time doesn't it (assuming we avoid ravines, ditches, and the barn doors...)? =20 Kevin =20 ________________________________ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Gary Casey Sent: Saturday, August 11, 2007 10:26 PM To: lml@lancaironline.net Subject: [LML] Re: Forced landing =20 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 =20 yeah, I think about that 20 extra knots a lot. =20 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. =20 Aren't you glad you asked? =20 Tom Gourley ------_=_NextPart_001_01C7DCA0.85B5E771 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Yeah, but isn’t that if you = hit a wall, another car, tree or slam into steep hill?  Skidding across a field = potentially gives more distance and time doesn’t it (assuming we avoid = ravines, ditches, and the barn doors…)?

 

Kevin

 

From: = Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Gary Casey
Sent: Saturday, August = 11, 2007 10:26 PM
To: = lml@lancaironline.net
Subject: [LML] Re: Forced = landing

 

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.

 <= /p>

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.

 <= /p>

Aren't you glad you asked?

 <= /p>

Tom Gourley

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