X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 17 Dec 2009 09:37:01 -0500 Message-ID: X-Original-Return-Path: Received: from web62504.mail.re1.yahoo.com ([69.147.75.96] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with SMTP id 4025470 for lml@lancaironline.net; Thu, 17 Dec 2009 06:35:18 -0500 Received-SPF: none receiver=logan.com; client-ip=69.147.75.96; envelope-from=charliekohler@yahoo.com Received: (qmail 94015 invoked by uid 60001); 17 Dec 2009 11:34:43 -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=yYbtOl/1WfF8NoHaixTlaciN+zwcSbqsvaiSbntvIQ7o+a9hN5tpAHMWEjQj6GF+QPBefPZxgkE5f3QSQfdxclibWR+WYMefoejCbt/9268/ogpbpXRvIqcF16Vs4nYuev+qVmixca0gyupu4N0WzFKR+C8NryuEoxQ3E3JjLo4=; X-Original-Message-ID: <295460.94001.qm@web62504.mail.re1.yahoo.com> X-YMail-OSG: .26dCAsVM1nyE286tIwzRKscN9eq4xskrPYJcYAVOapI0toSZz3NtzepvjMeE04zhXVj0Z4uvHymzUu7yUypgxyyrnMRs2329O4lDK4G4Gjbcm1aEA0UZEureJ1pcvxTZh2YBue2lq4jWsRMuctos7ZklWuguTHtAeRjQL1pm5uYKvv7iYEfJiDUp9ZVROTaieteu2vEI2ZbHpZ3LoXAwKvq356EFLpK_rrc7ilXQz_zebzGeMuQ4Cz8sQKkXFNonQRADoMmq8W26g9qq.I3awII6Q88VDVtTBX1vlUZoc4NyoDf5_CVmNGrTsztCDfUCqChrHz5CDnOBC0snMNyd0FXWln7UB0y3QrOGgjw6S5bBJQePY_mP1dogy9U48BWJUc4TmkrclL1Jd_hpOd4XXID1vxjBxnVRD00e0Dg Received: from [208.111.4.162] by web62504.mail.re1.yahoo.com via HTTP; Thu, 17 Dec 2009 03:34:43 PST X-Mailer: YahooMailRC/240.3 YahooMailWebService/0.8.100.260964 References: X-Original-Date: Thu, 17 Dec 2009 03:34:43 -0800 (PST) From: Charlie Kohler Subject: Re: [LML] Early LIV Vne X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1952032409-1261049683=:94001" --0-1952032409-1261049683=:94001 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi Fred,=0AYes I remember chipping in for the analysis.=0ABut I don't have = anything in my files. I recall that it was not a concern. .=C2=A0=0ACharlie= K.=0A=0ASee me on the web at =0Awww.Lancair-IV.com=0A=0A=0A=0A=0A=0A______= __________________________=0AFrom: Frederick Moreno =0ATo: lml@lancaironline.net=0ASent: Wed, December 16, 2009 10:02:30 = AM=0ASubject: [LML] Early LIV Vne=0A=0A=0AThanks to Charlie for posting the= results of Martin Hollman=E2=80=99s initial calculations for the Lancair I= V.=C2=A0 Recall that the original Lancair IV was unpressurized, 2900 pounds= , and had no=C2=A0 fuel in the outer parts of the wing.=C2=A0=C2=A0 It grew= to 3200 pounds, then 3550, and the=C2=A0 wing ended up wet from tip to tip= .=C2=A0 All of these changes=C2=A0 affected Vne.=0A=C2=A0=0ACharlie, do you= recall the work done to evaluate flutter when the wing tanks were initiall= y extended?=C2=A0 My recollection is that a lot of us wanted to fill the ou= ter bays as is commonly done now, and so we pooled some money =C2=A0in the = early 90=E2=80=99s and Martin did the analysis.=C2=A0 Results as I recall: = the flutter margin was reduced at altitude when the outer fuel bays had fue= l in them reducing the initial maximum speed.=C2=A0 However, most of this f= uel was burned off during climb and so the effect was minimal unless you fo= rgot to switch tanks during the long climb to 24,000.=C2=A0 =0A=C2=A0=0ADo = you suppose this led to the final Vne figure of 274 KIAS that is now painte= d on our airspeed indicators?=C2=A0 Or do you think Lance et al took Martin= =E2=80=99s figures, used them in dive tests to establish Vd, and then divid= ed by 1.1 to get the final figure (since=C2=A0 Vd is usually defined as 1.1= times Vne)?=C2=A0 =0A=C2=A0=0AAs for the discussion on HOW Vne is calculat= ed, I suspect a single figure is never actually calculated since so many fa= ctors affect the safety of the airplane at the edge of its operating envelo= pe.=C2=A0 I suspect that the manufacturer establishes a=C2=A0 target speed,= designs with some reserve (flutter margin, structural margin, compressibil= ity margin, etc.), and then does a dive test to Vd for certification.=C2=A0= Vne is then Vd divided by 1.1.=C2=A0=C2=A0 Details of Part 23 would tell t= he tale, perhaps. =0A=C2=A0=0AFred Moreno --0-1952032409-1261049683=:94001 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
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Hi Fred,
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Yes I remember chipping in fo= r the analysis.
But I don't have anything in my files. I recall that it = was not a concern. . 
=0A
Charlie K.
=0A
 =0A
See me on the web at
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=  
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=0A

=0A
=0A
=0AFrom:= Frederick Moreno <frederickmoreno@bigpond.com>
To: lml@lancaironline.net
Sent: Wed, December 16, 2009 10:02:30 AM<= BR>Subject: [LML] Early LIV= Vne

=0A= =0A=0A
=0A

Thanks to Charlie for p= osting the results of Martin Hollman=E2=80=99s initial calculations for the= Lancair IV.  Recall that the original Lancair IV was unpressurized, 2= 900 pounds, and had no  fuel in the outer parts of the wing. &nbs= p; It grew to 3200 pounds, then 3550, and the  wing ended up wet from = tip to tip.  All of these changes  affected Vne.

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Charlie, do you recall the w= ork done to evaluate flutter when the wing tanks were initially extended?&n= bsp; My recollection is that a lot of us wanted to fill the outer bays as i= s commonly done now, and so we pooled some money  in the early 90=E2= =80=99s and Martin did the analysis.  Results as I recall: the flutter= margin was reduced at altitude when the outer fuel bays had fuel in them r= educing the initial maximum speed.  However, most of this fuel was bur= ned off during climb and so the effect was minimal unless you forgot to swi= tch tanks during the long climb to 24,000. 

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Do you suppose this led to the final Vn= e figure of 274 KIAS that is now painted on our airspeed indicators?  = Or do you think Lance et al took Martin=E2=80=99s figures, used them in div= e tests to establish Vd, and then divided by 1.1 to get the final figure (s= ince  Vd is usually defined as 1.1 times Vne)? 

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=0A

As for the discussion on HOW= Vne is calculated, I suspect a single figure is never actually calculated = since so many factors affect the safety of the airplane at the edge of its = operating envelope.  I suspect that the manufacturer establishes a&nbs= p; target speed, designs with some reserve (flutter margin, structural marg= in, compressibility margin, etc.), and then does a dive test to Vd for cert= ification.  Vne is then Vd divided by 1.1.   Details of Part= 23 would tell the tale, perhaps.

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=0A=

Fred Moreno

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