X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 05 Jan 2013 11:19:58 -0500 Message-ID: X-Original-Return-Path: Received: from nm38-vm5.bullet.mail.bf1.yahoo.com ([72.30.239.21] verified) by logan.com (CommuniGate Pro SMTP 6.0.1) with ESMTPS id 5996054 for lml@lancaironline.net; Fri, 04 Jan 2013 19:29:54 -0500 Received-SPF: none receiver=logan.com; client-ip=72.30.239.21; envelope-from=n20087@yahoo.com Received: from [98.139.214.32] by nm38.bullet.mail.bf1.yahoo.com with NNFMP; 05 Jan 2013 00:29:17 -0000 Received: from [76.13.13.223] by tm15.bullet.mail.bf1.yahoo.com with NNFMP; 05 Jan 2013 00:29:17 -0000 Received: from [127.0.0.1] by smtp102-mob.biz.mail.ac4.yahoo.com with NNFMP; 05 Jan 2013 00:29:17 -0000 X-Yahoo-Newman-Id: 752200.1455.bm@smtp102-mob.biz.mail.ac4.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: 0T1lghsVM1kwstmjS0CUqAXjpDEofpbhDiIRJF8vSVjTyY6 yaDamZzajpooCHhw97Nra5Fncf3HcOmntOkX8MJVq9DGfkx5PNh4Cx_X.C41 BeSnNocOLAPb.XnjfkjHhhW.wpDwaJVyaeMSVmSg.croEkCIgjkBBiGOabUz r3sZCpXVEChUJa._4R32K_luBoYIq79bMkpe6_Vg8uG9gugrE1ScSnO3cpXw YqsQ2QCuv8hIYWV.A8Pm87sfduX9xrV2QtAbvJqZKH0yRKyUwd0mYIqEOfct jLQyaRVhoGQDhsUAsCNvK6A3vwDX05JHh8EHfnbEDKsZI4F8D0b9SlBw_bOT x3.2I48OK2DOfOC9oViqSabf12bg79OhNwOK0Lsy0hKp_pfEZZ3WvV116D5M 4h5tnEO3m9uQeBOdXFDdg1fTx5W7wqG3qcK5g68c_TGS2Cb_09MG19X7_etS z21bXOhQ- X-Yahoo-SMTP: NQQt3c2swBAKSrExoA1eZuT7_w-- Received: from [192.168.1.103] (n20087@98.185.56.123 with xymcookie) by smtp102-mob.biz.mail.ac4.yahoo.com with SMTP; 04 Jan 2013 16:29:17 -0800 PST Subject: Re: [LML] Re: stalls References: From: N20087 Content-Type: multipart/alternative; boundary=Apple-Mail-DB2E5D30-42E8-440F-8C97-6C09E163F1AD X-Mailer: iPad Mail (9B176) In-Reply-To: X-Original-Message-Id: <62CFF339-F5AD-4CC6-ABAD-9C5C8D687E2D@yahoo.com> X-Original-Date: Fri, 4 Jan 2013 19:29:17 -0500 X-Original-To: Lancair Mailing List Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-DB2E5D30-42E8-440F-8C97-6C09E163F1AD Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Jeff=20 Thanks for your time today Justin's phone number is. (757) 332-0537 Thanks Tom Sent from my iPad On Jan 3, 2013, at 11:30 AM, Jeff Edwards wrote: > Fred, >=20 > Well said! >=20 > Jeff >=20 > On Jan 3, 2013, at 9:16 AM, Frederick Moreno = wrote: >=20 >> =20 >> Bob wrote: >> =20 >> "Interesting: In all the twins I have flown not once was a stall an appro= ved procedure. Approach to stall sure, but never a full stall. So why must= Lancairs be stalled? >> Seems that the Lancairs are in the twin situation. So learn the feel at t= he approach to a stall (I have), us an AoA (I do), and the planes are safe a= nd a joy to fly (they are!)."=20 >> =20 >> Much wisdom there. >> =20 >> I feel compelled to add a bit of technical content to the discussion. Th= e Lancair IV wing was tailored to maintain laminar flow as far as possible o= ver the top and bottom of the wing. The resulting wing profile has exceptio= nally low frictional drag, but an unpredictable stall performance, a common c= haracteristic of wing profiles with long reaches of laminar flow. Laminar b= oundary layers are just not very energetic and can separate from the wing in= a flash. The flow may separate at the root and stay there (conventional st= all), or the separated air flow zone may suddenly spread all the way to the w= ing tip in which case a snap roll into a spin will be the result. And the s= pin may be unrecoverable.=20 >> =20 >> The LIV is not certified, and its stall capability along with many other c= haracteristics mean it never could be. It is Experimental. Don't treat it l= ike a certified or aerobatic airplane. It isn't. >> =20 >> Most airplanes (SNJ's for sure, they are trainers), most aerobatic aircra= ft like the Zlin (which have big fat leading edges which are highly stall re= sistant and relatively forgiving) and certified aircraft are relatively beni= gn in stall. Aerobatic aircraft and many others are guaranteed to be spin r= ecoverable. Virtually all modern certified aircraft) must have wing designs= that are compromised to provide buffet in advance of stall, they quit flyi= ng gently (and only slightly) with a straightforward relatively benign stall= , and provide normal straightforward recovery. I flew a friend's Cirrus an= d it was even more benign than my old C182. These airplanes were designed a= nd comprehensively tested to assure this benign and forgiving behavior each a= nd every time. >> =20 >> The Lancair IV most definitely was not. It was compromised in the directi= on of speed at any cost. And part of that cost is occasionally unpredictabl= e and potentially deadly stall behavior if not carefully and cautiously hand= led. It is the nature of the laminar flow wing design that yields such low= drag and high cruise speed coupled with other of the aircraft's characteris= tics and design features. >> =20 >> I was instructed by a 20,000+ hour Qantas captain who also flew a Lancair= IV and was the Australian national aerobatic champion. This guy really und= erstands unusual flight attitudes and aerodynamics. His instructions for th= e LIV practice were approach to stall at 10,000 feet in the landing configur= ation, an IRONCLAD rule that the ball be kept EXACTLY in the center, and the= n immediate recovery after the initial break. All this practice was done in= the landing configuration except for a couple of very cautious approach to s= tall tests with airplane clean which we did to establish a calibration point= for my angle of attack indicator. He was adamant: once that data point is c= ollected, there is no reason to go back there again. >> =20 >> He emphasized that there are airplanes that you just don't stall - ever -= because they bite. Many swept wing aircraft are in this category. On tho= se the stall can progress from root to wing tip very rapidly and the airplan= e then immediately rolls on its back and drops into a spin. On the Lancair,= a deep stall with ball out of center can on occasion enter an unrecoverable= spin. Let the ball get far enough out of center and it will almost certain= ly drop into a spin. >> =20 >> In short, he said, there is absolutely NO REASON to put a Lancair IV into= a deep stall. Slow flight practice, fine. Nibble at stall (approach to st= all) also fine subject to ball in the middle and 10,000 feet. Get ball out o= f center and/or hold the stall a bit too long and the outcome maybe fine 9 o= ut of 10 times, but you may get an unrecoverable spin on the tenth. Withou= t a spin chute and a personal parachute, exploring that territory is definit= ely test pilot stuff, so you better train and equip accordingly. >> =20 >> Stay away from everything except the approach to stall with ball centered= , use an angle of attack indicator (should be mandatory in these aircraft), p= ractice some slow flight maneuvers at 10,000 feet, and practice forced landi= ngs.=20 >> =20 >> But deliberately putting the airplane into a deep stall is Russian Roulet= te. Many aircraft are like this. Why go there? >> =20 >> Fred Moreno --Apple-Mail-DB2E5D30-42E8-440F-8C97-6C09E163F1AD Content-Transfer-Encoding: 7bit Content-Type: text/html; charset=utf-8
Jeff 

Thanks for your time today

Justin's phone number is. (757) 332-0537

Thanks

Tom

Sent from my iPad

On Jan 3, 2013, at 11:30 AM, Jeff Edwards <vtailjeff@aol.com> wrote:

Fred,

Well said!

Jeff

On Jan 3, 2013, at 9:16 AM, Frederick Moreno <frederickmoreno@bigpond.com> wrote:

 
Bob wrote:
 
"Interesting: In all the twins I have flown not once was a stall an approved procedure.  Approach to stall sure, but never a full stall.  So why must Lancairs be stalled?
Seems that the Lancairs are in the twin situation.  So learn the feel at the approach to a stall (I have), us an AoA (I do), and the planes are safe and a joy to fly (they are!)." 
 
Much wisdom there.
 
I feel compelled to add a bit of technical content to the discussion.  The Lancair IV wing was tailored to maintain laminar flow as far as possible over the top and bottom of the wing.  The resulting wing profile has exceptionally low frictional drag, but an unpredictable stall performance, a common characteristic of wing profiles with long reaches of laminar flow.  Laminar boundary layers are just not very energetic and can separate from the wing in a flash.  The flow may separate at the root and stay there (conventional stall), or the separated air flow zone may suddenly spread all the way to the wing tip in which case a snap roll into a spin will be the result.  And the spin may be unrecoverable. 
 
The LIV is not certified, and its stall capability along with many other characteristics mean it never could be.  It is Experimental.  Don't treat it like a certified or aerobatic airplane.  It isn't.
 
Most airplanes (SNJ's for sure, they are trainers), most aerobatic aircraft like the Zlin (which have big fat leading edges which are highly stall resistant and relatively forgiving) and certified aircraft are relatively benign in stall.  Aerobatic aircraft and many others are guaranteed to be spin recoverable.  Virtually all modern certified aircraft) must have wing designs that  are compromised to provide buffet in advance of stall, they quit flying gently (and only slightly) with a straightforward relatively benign stall, and provide normal straightforward recovery.   I flew a friend's Cirrus and it was even more benign than my old C182.  These airplanes were designed and comprehensively tested to assure this benign and forgiving behavior each and every time.
 
The Lancair IV most definitely was not. It was compromised in the direction of speed at any cost.  And part of that cost is occasionally unpredictable and potentially deadly stall behavior if not carefully and cautiously handled.   It is the nature of the laminar flow wing design that yields such low drag and high cruise speed coupled with other of the aircraft's characteristics and design features.
 
I was instructed by a 20,000+ hour Qantas captain who also flew a Lancair IV and was the Australian national aerobatic champion.  This guy really understands unusual flight attitudes and aerodynamics.  His instructions for the LIV practice were approach to stall at 10,000 feet in the landing configuration, an IRONCLAD rule that the ball be kept EXACTLY in the center, and then immediate recovery after the initial break.  All this practice was done in the landing configuration except for a couple of very cautious approach to stall tests with airplane clean which we did to establish a calibration point for my angle of attack indicator.  He was adamant: once that data point is collected, there is no reason to go back there again.
 
He emphasized that there are airplanes that you just don't stall - ever -  because they bite.  Many swept wing aircraft are in this category.  On those the stall can progress from root to wing tip very rapidly and the airplane then immediately rolls on its back and drops into a spin.  On the Lancair, a deep stall with ball out of center can on occasion enter an unrecoverable spin.  Let the ball get far enough out of center and it will almost certainly drop into a spin.
 
In short, he said, there is absolutely NO REASON to put a Lancair IV into a deep stall.  Slow flight practice, fine.  Nibble at stall (approach to stall) also fine subject to ball in the middle and 10,000 feet.  Get ball out of center and/or hold the stall a bit too long and the outcome maybe fine 9 out of 10 times, but you may get an unrecoverable spin on the  tenth.  Without a spin chute and a personal parachute, exploring that territory is definitely test pilot stuff, so you  better train and equip accordingly.
 
Stay away from everything except the approach to stall with ball centered, use an angle of attack indicator (should be mandatory in these aircraft), practice some slow flight maneuvers at 10,000 feet, and practice forced landings. 
 
But deliberately putting the airplane into a deep stall is Russian Roulette.  Many aircraft are like this.  Why go there?
 
Fred Moreno
--Apple-Mail-DB2E5D30-42E8-440F-8C97-6C09E163F1AD--