X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from omr-d06.mx.aol.com ([205.188.109.203] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6807937 for lml@lancaironline.net; Mon, 31 Mar 2014 13:42:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.109.203; envelope-from=Sky2high@aol.com Received: from mtaomg-mbd02.mx.aol.com (mtaomg-mbd02.mx.aol.com [172.26.252.16]) by omr-d06.mx.aol.com (Outbound Mail Relay) with ESMTP id EAB81701EAEF9 for ; Mon, 31 Mar 2014 13:41:34 -0400 (EDT) Received: from core-mlc005b.r1000.mail.aol.com (core-mlc005.r1000.mail.aol.com [172.29.188.211]) by mtaomg-mbd02.mx.aol.com (OMAG/Core Interface) with ESMTP id B273A3800008C for ; Mon, 31 Mar 2014 13:41:34 -0400 (EDT) From: Sky2high@aol.com Full-name: Sky2high Message-ID: <225b7.6f83427c.406b02ce@aol.com> Date: Mon, 31 Mar 2014 13:41:34 -0400 (EDT) Subject: Re: [LML] Re: FW: Adding an AOA To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_225b7.6f83427c.406b02ce_boundary" X-Mailer: AOL 9.6 sub 168 X-Originating-IP: [24.14.166.87] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1396287694; bh=362pnuHO+UO8Of/98ZhSG4ID8nyI6fZiMtsaN466/mc=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=XqHEFljfYEXsO6PLUTAXk0xJ9QOjA+ng3gBza+8wWDCYTnO9EE8/HweZKAxnAHMNX KXHeZusQpgorz4cQ5A1QhfnTdSr4MZIBvxqBx4qw1uNw1tfKTPh4wl5AN/y7uFkOQj +TFRx7DpbGUZVYn39rlpO/MYW6JkngFMVhVQZ6+o= x-aol-sid: 3039ac1afc105339a8ce4220 --part1_225b7.6f83427c.406b02ce_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Doug,=20 =20 There is always room for refinement. =20 =20 A fighter pilot is not a Lancair pilot. Did he land your plane? Perhaps= =20 your question would be best answered by an experienced Lancair Instructor. =20 In certificated type airplanes that are built to the same specs and on=20 jigs, Vso is test flight determined - perhaps for max gross weight, rearwa= rd=20 CG loading, etc. Perhaps not. But, usually these aircraft go through=20 thorough stall tests at various flaps setting, weights and CGs with the st= uff=20 out. Then Vso is determined in reality or is computed and verified from= =20 design specs. =20 Notice that V speeds are IASs. This can work because the IAS indication= =20 is calibrated via flight test and the correction data for position,=20 instrument and system error is noted in the POH. Of course, one wonders i= f the=20 correction data was obtained at all attitudes (AOA) and speeds. =20 I believe your aircraft is unique as denoted in the manufacturer's field on= =20 the registration form. So, has your ASI been calibrated? Was Vso =20 determined through exhaustive tests at differing parameters? =20 I don't know if you can get creative with your AOA system settings as I am= =20 not familiar with it. I did use the forerunner to the Advance Systems=20 system that uses upper and lower wing pressures along with pitot-static da= ta=20 to determine AOA. The slope of the straight line function was established= =20 by flight-setting two points on that line.=20 =20 Vso x 1.3 (if a useful Vso is known) may not provide enough safety margin= =20 for high performance Lancairs in differing configurations and weather=20 conditions - like turbulence on final or trying to fly close in square pat= terns. =20 There are techniques to overcome slowness or dangerous flat approaches such= =20 as a steeper approach angle to retain enough kinetic energy for flight =20 path corrections, although this requires care to stop the descent high eno= ugh=20 above the runway. =20 Good luck, =20 Scott Krueger. =20 =20 In a message dated 3/31/2014 6:35:55 A.M. Central Daylight Time, =20 douglasbrunner@earthlink.net writes: =20 Scott,=20 I understand that the AOA takes into account atmospheric conditions, g=20 loading, weight of the plane, etc. That is why I am interested in it rath= er=20 than just using airspeed. My problem is that one of the points to be used= =20 for calibration is, in my opinion, a subjective point.=20 You say that 1.3 Vso is dangerous with a high performance wing. What=20 number is a better one?=20 I was taught to fly final at 110 and to slow to 90 over the numbers =E2=80= =93=20 which is what I normally do. Recently, I flew with a retired fighter pilo= t who=20 told me I was too fast on final. I told him that it was better to be too = =20 fast and land long than be too slow and stall. But it started me thinking= =20 about a more optimal speed given how much runway I frequently use.=20 =20 =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of =20 Sky2high@aol.com Sent: Sunday, March 30, 2014 5:24 PM To: lml@lancaironline.net Subject: [LML] Re: FW: Adding an AOA =20 Doug, =20 =20 Sophisticated AOA indications take into account atmospheric conditions and= =20 G-loading along with IAS. In theory, there are straight line functions=20 between interesting points on the relevant AOA such as best glide, stall,= =20 etc. The old fashioned 1.3 Vso is dangerous in aircraft with high perform= ance=20 wings - because the stall speed does vary with G-load and, uh, the air. = =20 In Lancairs, 1.3 Vso does not provide proper margins in all cases. =20 =20 The sophisticated AOA systems need only 2 points on the straight line to = =20 calibrate the function (uh. the parallel straight line moves because of th= e=20 other parameters. Some system calibrations do not require the stall point= =20 as one measure (see Advanced Systems). Some require the zero G (zero=20 lift) point as one. Be careful. =20 =20 Simpler system rely merely on AOA to the relative wind. This is useful=20 because exceeding the stall AOA results in a stall. The sophisticated =20 systems yield other useful information (best glide, etc). =20 =20 Do further study to educate yourself about AOA. =20 =20 Scott Krueger =20 =20 =20 =20 In a message dated 3/30/2014 2:35:00 P.M. Central Daylight Time,=20 _douglasbrunner@earthlink.net_ (mailto:douglasbrunner@earthlink.net) writ= es: =20 Terrence,=20 There is no =E2=80=9Cangle=E2=80=9D to mark. Both instruments use an arra= y of colored=20 lights - in both, the top colored light is a red arrow pointing down =E2= =80=93 =20 presumably this is to indicate a stall.=20 The way that both are made to be used is to define a safe speed (roughly= =20 1.3 Vso) that can be used during landing (and other maneuvers)=20 My question was whether to set it to 1.3 Vso or to do the maneuver=20 described in the setup.=20 D. Brunner=20 =20 =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of=20 Terrence O'Neill Sent: Sunday, March 30, 2014 2:18 PM To: _lml@lancaironline.net_ (mailto:lml@lancaironline.net)=20 Subject: [LML] Re: FW: Adding an AOA D.,=20 =20 =20 IMHO the prime purpose of an AOA is:=20 =20 To make the wing's STALL ANGLE visible to the pilot. You do that by=20 flying the plane and stalling it as you watch the AOA... then mark that a= ngle. =20 The next most useful AOA info is the best L/D or best R/C... done the same= =20 way... fly the plane while watching the best R/C for a given power=20 setting, and make that angle. =20 =20 Terrence =20 L235/320 =20 N211AL =20 =20 =20 On Mar 30, 2014, at 9:23 AM, Douglas Brunner wrote: =20 I am thinking of adding an AOA to my plane. The two models that I am=20 looking at are the Bendix King KLR 10=20 (http://www.bendixking.com/Products/Flight-Controls-Indicators/Indicators/K= LR-10) and one of the Alpha Systems units=20 (http://www.alphasystemsaoa.com/)=20 My question has to do with the calibration. Both systems require a=20 calibration at 3 points:=20 =20 1. On Ground =20 2. Optimum Alpha Angle =20 3. Cruise =20 =20 The =E2=80=9Con ground=E2=80=9D and =E2=80=9Ccruise=E2=80=9D are self expl= anatory, however the=20 definition of =E2=80=9COptimum Alpha Angle=E2=80=9D seems a little =E2=80= =9Cloosey-goosey=E2=80=9D to me. Here=20 are the definitions: =20 =20 Alpha Systems =E2=80=9COptimum Alpha Angle=E2=80=9D =20 =C2=B7 Able to hold altitude =E2=80=93 as close to 0 VSI as possib= le, zero sink =20 =C2=B7 Full aileron, elevator and rudder control =E2=80=93 no buff= et or loss of=20 control surface stability =20 =20 Bendix King =E2=80=9COptimum Alpha Angle=E2=80=9D =20 =C2=B7 Able to hold altitude, 0 Vertical Speed, zero sink (5 to 10= fpm=20 climb OK) =20 =C2=B7 Full aileron, elevator and rudder control, not in a buffet,= =20 pilot to identify the set point by =20 pitching back slowly to a pitch no longer able to climb but able to hold= =20 altitude with full =20 control of the airplane. =20 =20 First of all, since this is a system meant to be used in landing (or at=20 least that is how I will mostly use it), I intend to calibrate the =E2=80= =9COptimum=20 Alpha Angle=E2=80=9D in landing configuration (gear down, full flaps). Ho= wever,=20 determining when I have =E2=80=9Cfull aileron, elevator and rudder control= =E2=80=9D isn=E2=80=99t all=20 that clear to me. I am sure that I can tell when I have aileron, elevator= =20 and rudder control =E2=80=93 but the =E2=80=9Cfull=E2=80=9D part is less c= lear. Does that mean a=20 full control deflection? Not something I am anxious to try that close to= =20 stall. =20 =20 Alternatively, I could just do a stall in landing configuration and set=20 the =E2=80=9COptimum Alpha Angle=E2=80=9D to 1.3 x stall. =20 =20 Advice? D. Brunner=20 N241DB 750 hours --part1_225b7.6f83427c.406b02ce_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
Doug,
 
There is always room for refinement. 
 
A fighter pilot is not a Lancair pilot.  Did he land your plane?&= nbsp;=20 Perhaps your question would be best answered by an experienced Lancair=20 Instructor.
 
In certificated type airplanes that are built to the sa= me=20 specs and on jigs, Vso is test flight determined - perhaps f= or=20 max gross weight, rearward CG loading, etc.  Perhaps not.  But,= =20 usually these aircraft go through thorough stall tests at various flap= s=20 setting, weights and CGs with the stuff out.  Then Vso is determined i= n=20 reality or is computed and verified from design specs.
 
Notice that V speeds are IASs.  This can work because t= he=20 IAS indication is calibrated via flight test and the correction data for=20 position, instrument and system error is noted in the POH.&n= bsp;=20 Of course, one wonders if the correction data was obtained at all attitudes= =20 (AOA) and speeds.
 
I believe your aircraft is unique as denoted in the manufacturer's fie= ld on=20 the registration form.  So, has your ASI been calibrated?  Was Vs= o=20 determined through exhaustive tests at differing parameters?
 
I don't know if you can get creative with your AOA=20 system settings as I am not familiar with it.  I did use the= =20 forerunner to the Advance Systems system that uses upper and lower win= g=20 pressures along with pitot-static data to determine AOA.  The slope of= the=20 straight line function was established by flight-setting two poin= ts on=20 that line. 
 
Vso x 1.3 (if a useful Vso is known) may not provide enough=20 safety margin for high performance Lancairs in differing configuration= s and=20 weather conditions - like turbulence on final or trying to fly close in squ= are=20 patterns.
 
There are techniques to overcome slowness or dangerous flat approaches= such=20 as a steeper approach angle to retain enough kinetic energy for flight=20 path corrections, although this requires care to stop the descent high= =20 enough above the runway.
 
Good luck,
 
Scott Krueger.
 
In a message dated 3/31/2014 6:35:55 A.M. Central Daylight Time,=20 douglasbrunner@earthlink.net writes:
=

Scott,

 

I=20 understand that the AOA takes into account atmospheric conditions, g load= ing,=20 weight of the plane, etc.  That is why I am interested in it rather = than=20 just using airspeed.  My problem is that one of the points to be use= d for=20 calibration is, in my opinion, a subjective point.

 

You=20 say that 1.3 Vso is dangerous with a high performance wing.  What nu= mber=20 is a better one?

 

I=20 was taught to fly final at 110 and to slow to 90 over the numbers =E2=80= =93 which is=20 what I normally do.  Recently, I flew with a retired fighter pilot w= ho=20 told me I was too fast on final.  I told him that it was better to b= e too=20 fast and land long than be too slow and stall.  But it started me=20 thinking about a more optimal speed given how much runway I frequently=20 use.

 

From: Lancair Ma= iling=20 List [mailto:lml@lancaironline.net] On Behalf Of=20 Sky2high@aol.com
Sent: Sunday, March 30, 2014 5:24=20 PM
To: lml@lancaironline.net
Subject: [LML] Re: FW: A= dding=20 an AOA

 

Terrence,

 

There=20 is no =E2=80=9Cangle=E2=80=9D to mark.  Both instruments use an ar= ray of colored lights=20 -  in both, the top colored light is a red arrow pointing down =E2= =80=93=20 presumably this is to indicate a stall.

 

The=20 way that both are made to be used is to define a safe speed (roughly 1.= 3=20 Vso) that can be used during landing (and other=20 maneuvers)

 

My=20 question was whether to set it to 1.3 Vso or to do the maneuver describ= ed in=20 the setup.

 

D.=20 Brunner

 

From:=20 Lancair Mailing List [mailto:lml@lancaironline.net]= On=20 Behalf Of Terrence O'Neill
Sent: Sunday, March 30, 2014 2= :18=20 PM
To: lml@lancaironline.net
S= ubject:=20 [LML] Re: FW: Adding an AOA

 

D.,

 

IMHO the prime purpose of an AOA=20 is:

 

To make th= e wing's=20 STALL  ANGLE visible to the pilot.  You do that by flying the= =20 plane and stalling it as you watch the AOA... then mark that=20 angle.

The next most useful AOA info is the best L/D or= best=20 R/C... done the same way... fly the plane while watching the best R/C f= or a=20 given power setting, and make that angle.

 

Terrence

L235/320

N211AL

 

On Mar 30, 2014, at 9:23 AM, Douglas Brunner=20 wrote:

 

 I am thinki= ng of=20 adding an AOA to my plane.  The two models that I am looking at ar= e the=20 Bendix King KLR 10 (http://www.bendixking.com/Products/Flight-Controls-Indica= tors/Indicators/KLR-10)=20 and one of the Alpha Systems units (http://www.alphasystemsaoa.com= /)

My question= has to=20 do with the calibration.  Both systems require a calibration at 3= =20 points:

1.      On=20 Ground

2.      Optimum Alp= ha=20 Angle

3.      Cruise

 

The =E2=80= =9Con ground=E2=80=9D=20 and =E2=80=9Ccruise=E2=80=9D are self explanatory, however the definiti= on of =E2=80=9COptimum Alpha=20 Angle=E2=80=9D seems a little =E2=80=9Cloosey-goosey=E2=80=9D to me.&nb= sp; Here are the=20 definitions:

 

Alpha Syste= ms=20 =E2=80=9COptimum Alpha Angle=E2=80=9D

=C2=B7     &n= bsp;   Able to hol= d=20 altitude =E2=80=93 as close to 0 VSI as possible, zero sink

=C2=B7     &n= bsp;   Full ailero= n,=20 elevator and rudder control =E2=80=93 no buffet or loss of control surf= ace=20 stability

 

Bendix King= =20 =E2=80=9COptimum Alpha Angle=E2=80=9D

=C2=B7     &n= bsp;   Able to hol= d=20 altitude, 0 Vertical Speed, zero sink (5 to 10 fpm climb OK)

=C2=B7     &n= bsp;   Full ailero= n,=20 elevator and rudder control, not in a buffet, pilot to identify the set= =20 point by

pitching ba= ck=20 slowly to a pitch no longer able to climb but able to hold altitude wit= h=20 full

control of = the=20 airplane.

 

First of al= l,=20 since this is a system meant to be used in landing (or at least that is= how=20 I will mostly use it), I intend to calibrate the =E2=80=9COptimum Alpha= Angle=E2=80=9D in=20 landing configuration (gear down, full flaps).  However, determini= ng=20 when I have =E2=80=9Cfull aileron, elevator and rudder control=E2=80=9D= isn=E2=80=99t all that clear=20 to me.  I am sure that I can tell when I have aileron, elevator an= d=20 rudder control =E2=80=93 but the =E2=80=9Cfull=E2=80=9D part is less cl= ear.  Does that mean a=20 full control deflection?  Not something I am anxious to try that c= lose=20 to stall.

 

Alternative= ly, I=20 could just do a stall in landing configuration and set the =E2=80=9COpt= imum Alpha=20 Angle=E2=80=9D to 1.3 x stall.

 

Advice?

 

D.=20 Brunner

N241DB 750= =20 hours

 

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