X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 18 Jul 2012 11:33:22 -0400 Message-ID: X-Original-Return-Path: Received: from blu0-omc3-s16.blu0.hotmail.com ([65.55.116.91] verified) by logan.com (CommuniGate Pro SMTP 5.4.6) with ESMTP id 5656783 for lml@lancaironline.net; Tue, 17 Jul 2012 22:32:28 -0400 Received-SPF: neutral receiver=logan.com; client-ip=65.55.116.91; envelope-from=frederickmoreno@bigpond.com Received: from BLU0-SMTP44 ([65.55.116.73]) by blu0-omc3-s16.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Tue, 17 Jul 2012 19:31:53 -0700 X-Originating-IP: [58.169.231.171] X-Originating-Email: [frederickmoreno@bigpond.com] X-Original-Message-ID: X-Original-Return-Path: frederickmoreno@bigpond.com Received: from Razzle ([58.169.231.171]) by BLU0-SMTP44.phx.gbl over TLS secured channel with Microsoft SMTPSVC(6.0.3790.4675); Tue, 17 Jul 2012 19:31:51 -0700 MIME-Version: 1.0 X-Original-Date: Wed, 18 Jul 2012 10:31:32 +0800 Content-Type: multipart/alternative; charset="iso-8859-1"; boundary="------------Boundary-00=_KC4CNM13LVC000000000" X-Mailer: IncrediMail (6295203) From: Frederick Moreno References: X-FID: FLAVOR00-NONE-0000-0000-000000000000 X-Priority: 3 X-Original-To: "Lancair Mail (lml@lancaironline.net)" Subject: Re: [LML] Flutter/VNE X-OriginalArrivalTime: 18 Jul 2012 02:31:52.0061 (UTC) FILETIME=[7D65EAD0:01CD648D] --------------Boundary-00=_KC4CNM13LVC000000000 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Excellent observations and advice. =0D =0D I did slug through all that stuff in engineering school and learned enoug= h about flutter to decide that I have a hard limit for my LIV of 220 knots, beginning of the yellow arc which I have not exceeded except in flight testing and one sea level full throttle blast just to answer the questio= n: what is maximum speed in level flight for my non-turbo airplane, the best way to get a flat plate drag area. The only other exception was racing w= ith Brent Regan. Been there, done that, no need to do it again. =0D =0D Since then, I have seen no point in nibbling at the yellow arc since it i= s comfortably above cruise and descent airspeeds, at least for me. Debris fields have absolutely no attraction. =0D =0D Fearless (but thoughtful) Fred =0D =0D =0D =0D =0D -------Original Message-------=0D =0D From: cwfmd@yahoo.com=0D Date: 18/07/2012 3:32:17 AM=0D To: lml@lancaironline.net=0D Subject: [LML] Flutter/VNE=0D =0D This might be beating a dead horse, but flutter analysis, even in mil spe= c or FAA certified, is a bit of a black art. There's lots on non-linear, hard-to-model structural, aerodynamic, and math mysteries. A huge amount = of judgment and experience applies here.=0D In certified airplanes, we suspect they sample random structures off th= e line, over time, to verify the original flight test model. Or maybe even = go back to flight test, if mishaps or other reports suggest flutter. If you = are Chuck Yeager, you get to fly a notorious driven mass device, that drives = the oscillation at resonance (evil smile)=0D ( 2nd order systems are usually junior or senior level E school courses= , after 2nd yr Calculus and Diff-E. Even those who survived it, forgot the technique, if not applied regularly... State-space? Anyone? Anyone? )=0D How would we do, either testing(not) or sampling, when all the builders have varying experience, and factories are at separate locations?=0D Published VNE only applies to Lance's original build and his test on one article. I'm sure we signed a waiver to that effect in this process!=0D It would be fairly cheap to mount an Accelerometer out on the wing, and hook it up to an analog input on the EFIS. Certain frequencies and amplitudes could trigger a warning. This is the only way to be certain, o= f VNE, to the level indicated above, for Mil and FAA standards.=0D Y'all be careful out there=0D =0D =20 --------------Boundary-00=_KC4CNM13LVC000000000 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Excellent observations and advice. 
 
I did slug through all that stuff in engineering school and learned = enough about flutter to decide that I have a hard limit for my LIV o= f 220 knots, beginning of the yellow arc which I have not = exceeded except in flight testing and one sea level full throttle blast&n= bsp; just to answer the question: what is maximum speed in level flight f= or my non-turbo airplane, the best way to get a flat plate drag area.&nbs= p; The only other exception was racing with Brent Regan.  Been there= , done that, no need to do it again.
 
Since then, I have seen no point in nibbling at the yellow arc since= it is comfortably above cruise and descent airspeeds, at least for me.&n= bsp;  Debris fields have absolutely no attraction.
 
Fearless (but thoughtful) Fred 
 
 
 
 
-= ------Original Message-------
 
Date: 18/07/2012 3= :32:17 AM
Subject: [LML] Flu= tter/VNE
 
This might be beating a dead horse, but flutter analysis, even in mi= l spec or FAA certified, is a bit of a black art. There's lots on no= n-linear, hard-to-model structural, aerodynamic, and math mysteries. A hu= ge amount of judgment and experience applies here.
  In certified airplanes, we suspect they sample rand= om structures off the line, over time, to verify the original flight test= model. Or maybe even go back to flight test, if mishaps or other reports= suggest flutter. If you are Chuck Yeager, you get to fly a = notorious driven mass device, that drives the oscillation at resonance&nb= sp; (evil smile)
 (  2nd order systems are usually junior or senior lev= el E school courses, after 2nd yr Calculus and Diff-E. Even those who sur= vived it, forgot the technique, if not applied regularly... State-space? = Anyone? Anyone?   )
 How would we do, either testing(not) or sampling, when al= l the builders have varying experience, and factories are at separat= e locations?
Published VNE only applies to Lance's original build and his test on= one article. I'm sure we signed a waiver to that effect in this process!=
  It would be fairly cheap to mount an Accelerometer out on the= wing, and hook it up to an analog input on the EFIS. Certain frequencies= and amplitudes could trigger a warning. This is the only way to be certa= in, of VNE, to the level indicated above, for Mil and FAA standards.=
Y'all be careful out there
 
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