X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 28 Mar 2010 20:55:49 -0400 Message-ID: X-Original-Return-Path: Received: from web57502.mail.re1.yahoo.com ([66.196.100.69] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with SMTP id 4181431 for lml@lancaironline.net; Sun, 28 Mar 2010 07:48:16 -0400 Received-SPF: none receiver=logan.com; client-ip=66.196.100.69; envelope-from=casey.gary@yahoo.com Received: (qmail 18704 invoked by uid 60001); 28 Mar 2010 11:47:39 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=db4fU9cECWh0oe4QUNtOUAKH+H4Pg/LoAHs4qlIhLR59ouxkO+q06dzfibdmx7J3L3z4po77sUy9NzrFcg/PC/1DYEV3IxVZ+GZSOB3LJiKF2yN6ba8HiQNWRM4NrvPU5fSRQdFxtMe/71VUGIdJpGQU8kwOK89lacUsz9KSOpI=; X-Original-Message-ID: <202777.18523.qm@web57502.mail.re1.yahoo.com> X-YMail-OSG: AXmWuTQVM1kkuuzZ_D3i2YAtyhEjYwOEoOpJEwictOB7TAx tUTvjREekM8D2gmizBntpmH689vuWzK5RcZXDh2oQ2zX.BkjfnAjasb1MXEK CEAfHGHEyMMQ2XEtd9huJFU93ysmB47phEgSPD6OeokUX6jO6knJPWOvwvMD 2JTnUCXgvJDHk52ZTxAPV17rKCL3spxxyFMf8vaz6lbh3q8YOSoLEuSvkK0z 2LO2fo3oDGOtI_dCOA735TU9fBtmEneFatTLsXtsyXt0W29IQSd.hXazN9uY Eyn4jkOllq5g- Received: from [97.122.184.73] by web57502.mail.re1.yahoo.com via HTTP; Sun, 28 Mar 2010 04:47:38 PDT X-Mailer: YahooMailRC/324.3 YahooMailWebService/0.8.100.260964 References: X-Original-Date: Sun, 28 Mar 2010 04:47:38 -0700 (PDT) From: Gary Casey Subject: Re: Fox Article X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1204910672-1269776858=:18523" --0-1204910672-1269776858=:18523 Content-Type: text/plain; charset=us-ascii Comments on various posts: Yes, the 61-knot requirement is all about crash energy. It is equally significant for experimentals as it is for certified planes, even though it is not a requirement for experimentals. It's about physics. Energy to be dissipated goes up as the square of speed. And one safety expert said that the "serverity" of a crash goes up as the cube of speed. Double the speed and the energy goes up by a factor of 4 and has to be dissipated in half the time, making the crash 8 times as "severe." I'm not surprised that the study couldn't come to a conclusion, but a more correct statement would be "A survey of controlled emergency forced landings was unable to show a clear correlation...." The reason is obvious - there aren't enough controlled forced landings to overcome the variation in design and landing circumstances. The physics are clear - lower crash speeds are safer. So don't disregard the 61-knot requirement as irrelevant. Of course, any other speed is equally relevant. Yes, I think The FAA publication shortly after the beach landing incident caused needless confusion as it was not relevant to the accident. But that doesn't make it irrelevant. Higher (than average) stall speeds, in my mind, are still a hazard. But they are a hazard not because of the high stall speed itself, but that it is higher than the vast majority of experience most pilots have. Getting slow therefore might not be recognized as the hazard it is. Joe mentioned that training is "the key" to safety and I slightly disagree. It is certainly "a key" element, but knowledge, skill and other factors are all important. In the end the actions of the pilot are "the only" factor and the pilot deserves the credit (or blame). Let's not transfer it to something else. That would be like "that was a great landing - I'll have to congratulate your instructor." Just my 2 cents. Gary Casey ps: I love my AeroComposites prop ________________________________ I think 61 knots is about crash energy, not likelihood of falling out of the air. ... Why FAA jumped on this number that has no particular significance for experimental aircraft, I have no idea. ... Survivability of controlled emergency forced landings is not dependent upon landing stall speed and a clear correlation between safety and landing stall speed cannot be found. ... The Lancair aircraft that landed on the beach did not do so as a result of a stall, but mechanical failure. --0-1204910672-1269776858=:18523 Content-Type: text/html; charset=us-ascii
Comments on various posts:  Yes, the 61-knot requirement is all about crash energy.  It is equally significant for experimentals as it is for certified planes, even though it is not a requirement for experimentals.  It's about physics.  Energy to be dissipated goes up as the square of speed.  And one safety expert said that the "serverity" of a crash goes up as the cube of speed.  Double the speed and the energy goes up by a factor of 4 and has to be dissipated in half the time, making the crash 8 times as "severe."  I'm not surprised that the study couldn't come to a conclusion, but a more correct statement would be "A survey of controlled emergency forced landings was unable to show a clear correlation...."  The reason is obvious - there aren't enough controlled forced landings to overcome the variation in design and landing circumstances.  The physics are clear - lower crash speeds are safer.  So don't disregard the 61-knot requirement as irrelevant.  Of course, any other speed is equally relevant.  Yes, I think The FAA publication shortly after the beach landing incident caused needless confusion as it was not relevant to the accident.  But that doesn't make it irrelevant.  Higher (than average) stall speeds, in my mind, are still a hazard.  But they are a hazard not because of the high stall speed itself, but that it is higher than the vast majority of experience most pilots have.  Getting slow therefore might not be recognized as the hazard it is.  Joe mentioned that training is "the key" to safety and I slightly disagree.  It is certainly "a key" element,  but knowledge, skill and other factors are all important.  In the end the actions of the pilot are "the only" factor and the pilot deserves the credit (or blame).  Let's not transfer it to something else.  That would be like "that was a great landing - I'll have to congratulate your instructor."  Just my 2 cents.
Gary Casey
ps:  I love my AeroComposites prop

 I think 61 knots is about crash energy, not likelihood of falling out of the air.
...
Why FAA jumped on this number that has no particular significance for experimental aircraft, I have no idea.
...
Survivability of controlled emergency forced landings is not dependent upon landing stall speed and a clear correlation between safety and landing stall speed cannot be found.
...
The Lancair aircraft that landed on the beach did not do so as a result of a stall, but mechanical failure.

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