X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 02 Sep 2011 07:51:44 -0400 Message-ID: X-Original-Return-Path: Received: from imr-da04.mx.aol.com ([205.188.105.146] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5110981 for lml@lancaironline.net; Thu, 01 Sep 2011 17:59:13 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.146; envelope-from=vtailjeff@aol.com Received: from mtaout-db06.r1000.mx.aol.com (mtaout-db06.r1000.mx.aol.com [172.29.51.198]) by imr-da04.mx.aol.com (8.14.1/8.14.1) with ESMTP id p81LwU5f032400 for ; Thu, 1 Sep 2011 17:58:30 -0400 Received: from [10.1.53.40] (mobile-198-228-196-231.mycingular.net [198.228.196.231]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by mtaout-db06.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPSA id 1856CE00009E; Thu, 1 Sep 2011 17:58:28 -0400 (EDT) References: In-Reply-To: Mime-Version: 1.0 (iPad Mail 8L1) Content-Type: multipart/alternative; boundary=Apple-Mail-2--547824574 X-Original-Message-Id: Content-Transfer-Encoding: 7bit X-Mailer: iPad Mail (8L1) From: vtailjeff@aol.com Subject: Re: [LML] Sir Isaac Re: LIV Shoulder Harness X-Original-Date: Thu, 1 Sep 2011 17:58:23 -0400 X-Original-To: Lancair Mailing List x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 1:2:392386016:93952408 X-AOL-SCOLL-URL_COUNT: 1 x-aol-sid: 3039ac1d33c64e60000432dd X-AOL-IP: 198.228.196.231 --Apple-Mail-2--547824574 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Water. Airbags help and at 62 knots (if I recall the lesson correctly) you n= eed about 9 feet to stop. Sent from my iPad On Sep 1, 2011, at 1:27 PM, William Miller wrote: > Okay, it's back to school time again, soooo...... > Alert- Spoiler- MathemaPhobes should not read past this point: "Word-Pro= blem" > =20 > Crash survivalbility is an important consideration, especially given the h= igh number of G-induced fatalities, in this speedy aircraft. Our main threat= here, is brilliantly described by Sir Isaac, 423 years ago, because the kin= etic energy goes up as the square of the velocity. If you are going 2 times a= s fast, as compared to your FAA certified 62 mph'er, when you hit the ditch,= or barrier at the boundary of your emergency farmer's field, 4 times the fo= rces must be disipated. 10-20 Gs in the X direction (eyeballs out) is the li= mit of survivable crash forces. > =20 > Scenario: On takeoff, I checked all the multi-engine monitors in the gree= n, the FF hit 44 gph as I rotated and all seemed well, even though I briefed= and reminded myself of a very low "abort threshold". If everything went wel= l in preflight (did I sample both tanks for water, strainer, and operational= fuel valve?), taxing, and runup, what are the odds of something catestrophi= c happening, in a properly maintained, firewall forward, certified engine? > Well today it did it, started sputtering at 850 feet, and quit completel= y just as I finished lowering the nose for glide, switching tanks, cycling m= ags, low boost then high, twidling the knobs.... NADA. Now I've got 450 feet= AGL and a nice 1000 foot farmers field 18 degrees to the left. If I just cl= ear the fence, on this end, and get full flaps touchdown at 89 KIAS (std day= ). MAGS, master, valve off, land, pop the door? (wait... is the gear up or d= own- which is better?) Do you hold it off for a smooth touchdown in ground e= ffect, or plant it like we learned for short runway ops? At 70 KIAS =3D 60 K= t GS =3D 30 meters/ second, how much distance do I need to survive this toda= y? > =20 > Hints: KE=3D 1/2 m v^2 1 G =3D 9.8 meter/sec^2 10 G =3D 98 meter/sec^= 2 > =20 > Newton: F =3D m a =3D KE/d or KE=3D m a d (mass drops out ! ) > =20 > Bonus question: What if my choices are water (ditching) vs unfriendly rock= y beach vs trees? > =20 > Remember, the most important crash survivability criterion is prevervation= of the space around the human, properly restrained. Would airbags help? I d= on't have enough data. > How 'bout 4 -5 point restraint - probably, but is there any data from cert= ification testing on the ES to Columbia to Cessna 400 certification? hmmm --Apple-Mail-2--547824574 Content-Transfer-Encoding: 7bit Content-Type: text/html; charset=utf-8
Water. Airbags help and at 62 knots (if I recall the lesson correctly)  you need about 9 feet to stop.

Sent from my iPad

On Sep 1, 2011, at 1:27 PM, William Miller <cwfmd@yahoo.com> wrote:

Okay, it's back to school time again, soooo......
Alert- Spoiler- MathemaPhobes should not read past this point:   "Word-Problem"
 
Crash survivalbility is an important consideration, especially given the high number of G-induced fatalities, in this speedy aircraft. Our main threat here, is brilliantly described by Sir Isaac, 423 years ago, because the kinetic energy goes up as the square of the velocity. If you are going 2 times as fast, as compared to your FAA certified 62 mph'er, when you hit the ditch, or barrier at the boundary of your emergency farmer's field, 4 times the forces must be disipated. 10-20 Gs in the X direction (eyeballs out) is the limit of survivable crash forces.
 
 Scenario: On takeoff, I checked all the multi-engine monitors in the green, the FF hit 44 gph as I rotated and all seemed well, even though I briefed and reminded myself of a very low "abort threshold". If everything went well in preflight (did I sample both tanks for water, strainer, and operational fuel valve?), taxing, and runup, what are the odds of something catestrophic happening, in a properly maintained, firewall forward, certified engine?
  Well today it did it, started sputtering at 850 feet, and quit completely just as I finished lowering the nose for glide, switching tanks, cycling mags, low boost then high, twidling the knobs.... NADA. Now I've got 450 feet AGL and a nice 1000 foot farmers field 18 degrees to the left. If I just clear the fence, on this end, and get full flaps touchdown at 89 KIAS (std day). MAGS, master, valve off, land, pop the door? (wait... is the gear up or down- which is better?) Do you hold it off for a smooth touchdown in ground effect, or plant it like we learned for short runway ops? At 70 KIAS = 60 Kt GS = 30 meters/ second, how much distance do I need to survive this today?
 
Hints:  KE= 1/2 m v^2   1 G = 9.8 meter/sec^2   10 G = 98 meter/sec^2
 
Newton:  F = m a = KE/d    or  KE= m a d   (mass drops out ! )
 
Bonus question: What if my choices are water (ditching) vs unfriendly rocky beach vs trees?
 
Remember, the most important crash survivability criterion is prevervation of the space around the human, properly restrained. Would airbags help? I don't have enough data.
How 'bout 4 -5 point restraint - probably, but is there any data from certification testing on the ES to Columbia to Cessna 400 certification?   hmmm
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