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Yes.  Interesting.  The -- by far -- most important function of the AOA =
is telling the pilot how close he is flying his wing to its stall angle.
Hadn't noticed the possible effect of washout and wingtip pressure  loss =
on the location of the pressure ports.
As regards the apparent drag rise of some designs, a lot can be learned =
from "Fluid Dynamic Drag" by Hoer ner ... a German aerodynamicist with a =
practical bent... did drag studies on al sorts of aircraft, from the =
Bf-109 up through the P-51 and Me-262 and airliners, even cars and =
stuff... An aero-engineer from McDonnell (remember them?) once told me =
his buddies at work considered Hoerner their guru.  Lots of stuff about =
drag causes and reduction in engine installations, radiators, flaps, =
cowling, etc., always with practical example.  Drag reduction is a lot =
cheaper than more horsepower.
I'm still thinking about cowl flaps.
T

On Oct 31, 2011, at 3:53 PM, Sky2high@aol.com wrote:

> Terry,
> =20
> It is interesting that we are talking about two different ways to =
represent AOA.  Another would be the leading edge stall warning tab seen =
on many std certified aircraft.  I have seen vanes used on many =
corporate jet aircraft.  Vanes definitely represent aircraft attitude =
relative to the airstream flowing and, as such, are clearly related to =
AOA as defined.  It is simple and easy to understand in its operation =
and implications.
> =20
> Pressure sensing "AOA" sensors are intriguing because of where they =
are located.  In my case, inboard of the wingtip rib and forward of the =
main spar.  In a 300 series Lancair this location is where there is =
significant washout and, in stable flight, the aileron remains somewhat =
reflexed.  I am not sure how this relates to the defined AOA (Chord to =
relative wind) in those areas of the wing affected by the flap and its =
TE that starts above the non-reflexed TE location and eventually drops =
below it.  The other confusing aspect is the attitude change that occurs =
as the flaps are extended and how that relates to the webinar discussion =
of AOA drag as the pitch change is trimmed out by up elevator.  The flap =
extension attitude change (pitch down) certainly decreases the wing tip =
AOA throughout the area covered by the aileron.  Good if you don't want =
the tips to stall before the wing root.=20
> =20
> Because of all that fancy footwork (no pun intended), the electronic =
AOA compensates for aircraft loading and other things that affect lift =
along with an indication of reaching best glide speed.  The AOA =
indication changes instantaneously with elevator movement.  It is best =
to consider the digital readout in tenths - like 00.0 to, say, 15.0 and =
that may be the reason to ignore the bouncing around in turbulence where =
the change is no more than + or - 1.0.  Perhaps I will go back out and =
do similar test only reporting the number and color of the chevron bars =
- then again, perhaps not since it is too much to write down - Hmmmm, =
maybe a video?
> =20
> Maybe we should just call my device a lift reserve indicator and leave =
it at that.  The other piece of data that the device uses is airspeed =
and I don't know what it would mean to try to pick a device reading and =
keep it constant while manipulating flaps and airspeed since it is =
defined for only two configurations, full reflex and partial flaps.
> =20
> The important part is that the nag yells "Angle, Angle, Push" into my =
headset at an approach to stall - allowing me to utilize another =
deteriorating sensory channel to the brain rather than overloading just =
one.
> =20
> BTW,  Aircraft tend to hit a slightly elastic speed wall, regardless =
of power, by virtue of their design.  Perhaps for that reason the 235's =
powered by 320's don't seem to reach the expected cruise potential (less =
than Vne).  The 300 series seems to respond better to added power.  Of =
course, then we are always cruising in the yellow arc in smooth air.  Be =
careful out there and note the desirability that the wing stalls before =
it fails in wild and wooly turbulence.  Stay inside the envelope.
> =20
> All very interesting.  Probably more by relating your "Bacon Saver" =
and the digital AOA mounted on the same airplane.  Does this =
experimenting ever end?
> =20
> Scott  =20
> =20
> In a message dated 10/31/2011 8:04:57 A.M. Central Daylight Time, =
troneill@charter.net writes:
> Scott,
>=20
> Very interesting, and I envy your performance.  With same power =
settings and altitude I think our 235/320 is about 15 to 20 KIAS slower =
than yours.  (I need cowl flaps.)
>=20
> Sometime after I wrote the detailed article on AOAs in the December =
1998 issue of Kitplanes Magazine, Jim Franz called and discussed his =
plans for making AOAs... which he did. Your installation must be the =
same as his, so i reviewed the 114 pages of its installation and =
operation manual.  Really complex, but does not really measure a wing's =
angle of attack, but instead, the digitally calculated lift available =
between a 'zero lift angle' and the maxim um lift available.=20
>  It also performs many additional more functions than my simple =
relative wind vane does not.  However, it does not perform some that my =
free vane does, such as show the AOAs above the stall angle, so the =
pilot can see exactly how much or how little he has to reduce the =
(stalled) AOA to get flying again.
> I didn't understand the large range of numbers (angles?)  digital =
Franz's AOA displays on the gage ... from zero up to more than 100...?  =
But I guess you quickly get familiar with what each number range =
represents, after you go through the calibration procedure.=20
>=20
> To calibrate a simple free-vane AOA I just stuck my Bacon Saver in the =
mounting tube, flew and noted what angle number the vane is pointing at =
--  at the stall, the approach, and if it's different with the flaps =
reflexed or down.
> Then I stuck on the small piece of striping tape of the color I like =
for each condition, and that's the calibration.
>=20
> I had asked - does your AOA indicator moves instantly with your =
elevator movement? Or is there lag.
> One interesting difference between Franz's AOA system and the simple =
vane display -- I see where you noted your AOA gage's digital numbers =
decreased when you held the airspeed constant at 120 kts. and moved the =
flaps from reflex to profile to 10 degrees down... and this I think =
seemed to you the opposite to what you expected...  i.e increased lift =
from deploying a    flap.
> But it is a correct indication, because you were holding the airspeed =
constant instead of holding the actual AOA constant.  I think the reason =
it appears contra-intuitive is because
> Franz's "AOA" is not really an AOA that measures ANGLES, but measures =
pressure differential ... between upper and lower wing surface ...  and =
compares that to -- and corrects for ---   what he calls a "zero lift =
angle" (which one calibrates by flying a zero-G maneuver, and which =
moves and varies with each wing/flap configuration) and the pressure =
increment between the top and lower wing surface at an airspeed... all =
of which must be calibrated.  Pretty complicated.
>=20
> A simple free-vane AOA just shows the angle between the actual =
relative wind and the wing's basic chord line, and has very =
angle-acurate marks on an indicator for the unchanging stall angle, and =
if desired, the angle one wants for approach, etc.=20
> I just made an angle scale behind the vane; others use a potentiometer =
shaft to mount the vane and read that out on a panel gage.=20
> I look with my eyeball at the AOA and my left hand on the stick =
adjusts the vane to read the desired angle during approach. =20
> Either way works; and what's important that with an AOA a pilot can =
see how close he is flying to his wing's stall angle -- or to its =
'maximum lift angle' -- and avoid stalling.
>=20
> Terry
>=20
>=20
>=20
>=20
>=20
>=20
>=20
> On Oct 28, 2011, at 3:43 PM, Sky2high@aol.com wrote:
>=20
>> Terrence,
>> =20
>> Thanks for the information.  Of course you are right that the AOA is =
affected by the elevator loading up the wing.  Other than that and the =
worthwhile EAA webinar that David pointed out, I can only report the =
following as "interesting" on my 320.  I have rigged my ailerons to a =
slight up position to eliminate any wobble from lash.  Because they are =
rigged up, the very minimal adverse yaw from aileron deflection =
(differential bell cranks) is further reduced because the down going =
aileron has to go further before it is down.  Another factor that cannot =
be ignored is the eerie reflex flapped wings.  They just don't quite =
perform the way presented in the EAA webinar.  I have the original Jim =
Franz digital AOA device (now Advanced Flight Systems) that utilizes the =
pressure differential betwixt the upper and lower wing along with =
pitot/static pressure (airspeed).  Beside the fancy chevron, a 3 digit =
representation of the AOA is also displayed.  The wing pressure pickups =
are located at the left wingtip.  Today I went for a flight with the =
following results:
>> =20
>> My CG was at 25.5 (about 1.5" aft of most forward) at a TOW of about =
1540 lbs.
>> At 6500 MSL (5800 Dalt) and 3C OAT, I was indicating 180 KIAS (195 =
KTAS), 24.8" MAP and 2480 RPM.
>> =20
>> At the 180 cruise:
>> 1. The AOA read 16 and 19 in either a right or left 20 degree level =
banked turn (I used the AP for this test).=20
>> 2. 1/2 rudder pushes does induce a slight roll with an AOA of 18.  If =
one does not attempt to hold level, the roll to the left also starts a =
dive (no surprise there).
>> 3.  Cross controlled aileron induced 20 degree dutch rolls resulted =
in AOA readings of 18-19.  If the rudder was not used, the DG would =
swing about 10 degrees.
>> =20
>> At 120 KIAS (power appropriately back) and level flight with the ball =
centered:
>> 1. Flaps in reflex AOA =3D 42
>> 2. Flaps out of reflex (down 7 degrees) AOA =3D 27
>> 3. Flaps at take off position (about 10 degrees out of reflex) AOA =3D =
18
>> Note that this is at variance with the webinar that claimed the AOA, =
as measured from chord line to relative wind, increased as flaps were =
deployed.  Not so by my AOA pressure measurements.  Remember that the =
200/300 Lancairs have a very strong pitching moment as the flaps are =
moved.  In my case I required more up elevator as flaps were lowered and =
more power to overcome added drag and maintain level flight at the =
steady airspeed.
>> =20
>> At best glide (106 KIAS), flaps in full reflex:
>> 1. AOA =3D 58
>> 2. Left 1/2 rudder induced a roll, AOA =3D 62
>> 3. Right 1/2 rudder induced a roll, AOA =3D 64
>> =20
>> Level fight at a lower altitude  in light chop saw the AOA go + or - =
10
>> =20
>> On descent to the airport at 500 fpm and 135 KIAS, the AOA hovered =
around zero.
>> =20
>> I did not record data in the pattern as the tower asked that I keep =
ahead of the following jet.  Besides, my short term memory is not up to =
the task of remembering multiple data points.
>> =20
>> Scott
>> =20
>> =20
>> =20
>> In a message dated 10/27/2011 3:15:16 P.M. Central Daylight Time, =
troneill@charter.net writes:
>> Scott, Au contraire mon ami. =20
>> You saw my wing with its free-vane-type AOA, mounted at BL+47. =20
>> In flight it is my trim tab that maintains the wing's AOA for each =
airspeed and tail loading (CG vs lift center), and only my light =
fingertip pressure make corrections for altitude/power).=20
>> This works in my bird in calm or gusty air.
>> I haven't flown with one of the 'magic lights' or digital AOAs, but =
the results should be about the same as with my free-vane-type AOA. =20
>> Watch your AOA, -hands off-, in gusty or smooth air, zooming up or =
diving, and note that the AOA stays as trimmed.=20
>> But with - hands on - the stick,  I am overriding the trim, and =
control of the wing's AOA, and it moves instantly with my stick =
movement, as if it were string-attached vane-to-stick. =20
>> If your AOA doesn't react like that, it's got lag in the system.  =
What kind of AOA do you have?
>>=20
>> Operating near the stall, at high AOAs (regardless of airspeed) the =
wing's AOA is commanded by the stabilizer/elevator/trim unless =
overridden by the pilot ... who is responsible for his input.
>> If he deliberately pulls the wing into a stall AOA, (which he can SEE =
on this AOA) he is deliberately giving away his pitch control.  Then he =
has to use the elevator-stabilizer to reduce the wing's AOA.  In the =
CAFE test of a 320/360 the pilot noted that the stall recovery was =
marginal.  In a professional/military test pilot report at =
(www.eaa1000.av.org/fltrpts/lanc360/hq.htm)  gives the details regarding =
high and stall AOA and recovery of the small tail LNC2s, which prompted =
me to put slots on my horizontal stabilizer.  I wasn't sure how these =
tests applied to the 235/320, but I thought -- close enough.  The =
alternative was to be cautious about stalling the plane, and, to also be =
able to SEE how close I was to the stall AOA.
>>=20
>> You mentioned  steep turns to final.  It is not the bank angle but =
the pulling back on the stick for a balanced turn that increases the =
AOA.  I watch the AOA vane while pulling the wing into an untrimmed AOA, =
but keep the AOA vane angle well below the marked stall AOA, (my tab =
trims only down to about 85 w/ gear down and flaps, rear CG) and the AOA =
responds just as though I had a string attaching the stick to the free =
vane.  I keep about 5 degrees in reserve for a little extra lift needed =
to flare and slow to touchdown.=20
>> =20
>> When first flying with my homemade AOA (1970) while testing my O' =
Model W, I was delighted to be able to fly very close to the NACA 4415's =
stall AOA and minimum airspeed with confidence, and thought I'd see if i =
could land right at the start of the runway and turn off at the run-up =
area... so when I got right down to the runway to flare and pulled =
back... there was no more CL at that high angle.  Some airfoils have a =
gradual peak a little past the top of the lift curve, and I'd been =
flying in that max lift area.  So I made a 'carrier landing' ... that =
is, I flew right into the concrete with a big bang..  Fortunately I had =
made the landing gear nice and strong.  I got out and looked everything =
over, and no damage, except to my ego.  But I learned to respect the =
airfoil's gradual max lift peak, add reduced my AOA down to final.=20
>>=20
>> If (hands off) a plane wants to pitch up or down regardless of the =
pitch trim setting,  then it is dangerously unstable because the CG is =
aft of the plane's lift center ... aft of where the CG is not supposed =
to be... unless you have artificial stabilization.
>>=20
>> Regarding slowing in in chop or turbulence, I don't know what would =
cause that. Maybe some small zone on the plane is just a gentle enough =
curve that it is low drag unless bumped..?  Some planes have a 'bucket' =
of low drag in a narrow AOA range, and have to be flown fast enough to =
get the AOA down into the bucket at cruise power... but if approached =
slowly by setting the cruise power too early they don;t get up to speed. =
 So the pilot leaves climb power on until he's in the bucket, and then =
can reduce power and stay there.
>>=20
>> My comments are based on my own experience flying with my vane, in my =
Model W, in my Magnum Pickup, a Mitchell B-10 Wing, in  a Dragonfly, a =
Challenger, and in the 235/320. =20
>> I don't want to be stalled either.  : )
>>=20
>> Terrence
>>=20
>> On Oct 27, 2011, at 10:08 AM, Sky2high@aol.com wrote:
>>=20
>>> Terrence,
>>> =20
>>> Yes, but the statement is too simple and is only true in smooth air =
under a constant load.  The flying wing AOA (angle between wing and air =
flow) is not always under control of the pilot.  Operating at an air =
speed near the stall AOA allows the wing to stall if the air is not =
smooth such as perturbations from turbulence (wake, wind shear, gusts, =
etc.)=20
>>> =20
>>> Pilot control is a component when operating near the stall AOA and =
loading up the wing without increasing the air flow that increases the =
AOA leading to a wing stall (i.e. low speed base to final turn where the =
bank angle is increased and the stick is pulled to line up with the =
runway on final).
>>> =20
>> =3D
>=20
> =3D


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<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><font =
class=3D"Apple-style-span" size=3D"2">Yes. &nbsp;Interesting. &nbsp;The =
-- by far -- most important function of the AOA is telling the pilot how =
close he is flying his wing to its stall angle.</font><div><font =
class=3D"Apple-style-span" size=3D"2">Hadn't noticed the possible effect =
of washout and wingtip pressure &nbsp;loss on the location of the =
pressure ports.</font></div><div><font class=3D"Apple-style-span" =
size=3D"2">As regards the apparent drag rise of some designs, a lot can =
be learned from "Fluid Dynamic Drag" by Hoer ner ... a German =
aerodynamicist with a practical bent... did drag studies on al sorts of =
aircraft, from the Bf-109 up through the P-51 and Me-262 and airliners, =
even cars and stuff... An aero-engineer from McDonnell (remember them?) =
once told me his buddies at work considered Hoerner their guru. =
&nbsp;Lots of stuff about drag causes and reduction in engine =
installations, radiators, flaps, cowling, etc., always with practical =
example. &nbsp;Drag reduction is a lot cheaper than more =
horsepower.</font></div><div><font class=3D"Apple-style-span" =
size=3D"2">I'm still thinking about cowl flaps.</font></div><div><font =
class=3D"Apple-style-span" size=3D"2">T</font></div><div><br><div><div>On =
Oct 31, 2011, at 3:53 PM, <a =
href=3D"mailto:Sky2high@aol.com">Sky2high@aol.com</a> wrote:</div><br =
class=3D"Apple-interchange-newline"><blockquote type=3D"cite">

<meta content=3D"text/html; charset=3DUS-ASCII" =
http-equiv=3D"Content-Type">
<meta name=3D"GENERATOR" content=3D"MSHTML 9.00.8112.16437">
<div style=3D"FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 10pt" =
id=3D"role_body" bottommargin=3D"7" leftmargin=3D"7" rightmargin=3D"7" =
topmargin=3D"7"><font id=3D"role_document" color=3D"#000000" size=3D"2" =
face=3D"Arial">
<div>Terry,</div>
<div>&nbsp;</div>
<div>It is interesting that we are talking about two different ways to =
represent=20
AOA.&nbsp; Another would be the leading edge&nbsp;stall warning&nbsp;tab =
seen on=20
many std certified aircraft.&nbsp; I have seen vanes used&nbsp;on many =
corporate=20
jet aircraft.&nbsp; Vanes definitely represent aircraft attitude =
relative to the=20
airstream flowing and, as such, are clearly related to AOA as =
defined.&nbsp; It=20
is simple and easy to understand in&nbsp;its operation and =
implications.</div>
<div>&nbsp;</div>
<div>Pressure sensing "AOA" sensors are intriguing because of where they =
are=20
located.&nbsp; In my case, inboard of the wingtip rib and forward of the =
main=20
spar.&nbsp; In a 300 series Lancair this location is where there is =
significant=20
washout and, in stable flight, the aileron&nbsp;remains somewhat =
reflexed.&nbsp;=20
I am&nbsp;not sure how this relates to the defined AOA (Chord to =
relative wind)=20
in those areas of the wing affected by the flap and its TE&nbsp;that =
starts=20
above the non-reflexed TE location and eventually drops below it.&nbsp; =
The=20
other confusing aspect is the attitude change that occurs as the flaps =
are=20
extended and how that relates to the webinar discussion of AOA drag as =
the pitch=20
change is trimmed out by up elevator.&nbsp; The flap extension attitude =
change=20
(pitch down) certainly decreases the wing tip AOA throughout the area =
covered by=20
the aileron.&nbsp; Good if you don't want the tips to stall =
before&nbsp;the wing=20
root.&nbsp; </div>
<div>&nbsp;</div>
<div>Because of all that fancy footwork (no pun intended), the =
electronic=20
AOA&nbsp;compensates for aircraft&nbsp;loading and other things that =
affect lift=20
along with an indication of reaching&nbsp;best glide speed.&nbsp; The=20
AOA&nbsp;indication changes instantaneously with elevator =
movement.&nbsp; It is=20
best to consider the digital readout in tenths - like 00.0 to, say, 15.0 =
and=20
that may be the reason to ignore the bouncing around in turbulence where =
the=20
change is no more than + or - 1.0.&nbsp; Perhaps I will go back out =
and&nbsp;do=20
similar test only reporting the number&nbsp;and color of the =
chevron&nbsp;bars -=20
then again, perhaps not since it is too much to write down - Hmmmm, =
maybe a=20
video?</div>
<div>&nbsp;</div>
<div>Maybe we should just call my device a lift reserve indicator and =
leave it=20
at that.&nbsp; The other piece of data that the device uses is airspeed =
and I=20
don't know what it would mean to try to pick a device&nbsp;reading and =
keep=20
it&nbsp;constant while manipulating flaps and airspeed since it is =
defined for=20
only two configurations, full reflex and partial flaps.</div>
<div>&nbsp;</div>
<div>The important part is that the nag yells "Angle, Angle, Push" into =
my=20
headset at an approach to stall - allowing me to utilize another =
deteriorating=20
sensory channel to the brain rather than overloading just one.</div>
<div>&nbsp;</div>
<div>BTW,&nbsp; Aircraft tend to hit&nbsp;a slightly elastic&nbsp;speed =
wall,=20
regardless of power, by virtue of their design.&nbsp; Perhaps for that =
reason=20
the 235's powered by 320's don't seem to reach&nbsp;the expected=20
cruise&nbsp;potential (less than Vne).&nbsp; The 300 series seems to =
respond=20
better&nbsp;to added power.&nbsp; Of course, then we are always cruising =
in the=20
yellow arc in smooth air.&nbsp; Be careful out there and&nbsp;note the=20=

desirability&nbsp;that the wing stalls before it fails in wild and wooly=20=

turbulence.&nbsp; Stay inside the envelope.</div>
<div>&nbsp;</div>
<div>All very interesting.&nbsp; Probably more by relating your "Bacon =
Saver"=20
and the digital AOA mounted on the same airplane.&nbsp; Does this =
experimenting=20
ever end?</div>
<div>&nbsp;</div>
<div>Scott&nbsp;&nbsp;&nbsp;</div>
<div>&nbsp;</div>
<div>
<div>In a message dated 10/31/2011 8:04:57 A.M. Central Daylight Time,=20=

<a href=3D"mailto:troneill@charter.net">troneill@charter.net</a> =
writes:</div>
<blockquote style=3D"BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; =
MARGIN-LEFT: 5px"><font style=3D"BACKGROUND-COLOR: transparent" =
color=3D"#000000" size=3D"2" face=3D"Arial">Scott,=20
  <div><br></div>
  <div>Very interesting, and I envy your performance. &nbsp;With same =
power=20
  settings and altitude I think our 235/320 is about 15 to 20 KIAS =
slower than=20
  yours. &nbsp;(I need cowl flaps.)</div>
  <div><br></div>
  <div>Sometime after I wrote the detailed article on AOAs in the =
December 1998=20
  issue of Kitplanes Magazine, Jim Franz called and discussed his plans =
for=20
  making AOAs... which he did. Your installation must be the same as =
his, so i=20
  reviewed the 114 pages of its installation and operation manual. =
&nbsp;Really=20
  complex, but does not really measure a wing's angle of attack, but =
instead,=20
  the digitally calculated lift available between a 'zero lift angle' =
and the=20
  maxim um lift available.&nbsp;</div>
  <div>&nbsp;It also performs many additional more functions than my =
simple=20
  relative wind vane does not. &nbsp;However, it does not perform some =
that my=20
  free vane does, such as show the AOAs above the stall angle, so the =
pilot can=20
  see exactly how much or how little he has to reduce the (stalled) AOA =
to get=20
  flying again.</div>
  <div>I didn't understand the large range of numbers (angles?) =
&nbsp;digital=20
  Franz's AOA displays on the gage ... from zero up to more than 100...?=20=

  &nbsp;But I guess you quickly get familiar with what each number range=20=

  represents, after you go through the calibration =
procedure.&nbsp;</div>
  <div><br></div>
  <div>To calibrate a simple free-vane AOA I just stuck my Bacon Saver =
in the=20
  mounting tube, flew and noted what angle number the vane is pointing =
at --=20
  &nbsp;at the stall, the approach, and if it's different with the flaps=20=

  reflexed or down.</div>
  <div>Then I stuck on the small piece of striping tape of the color I =
like for=20
  each condition, and that's the calibration.</div>
  <div><br></div>
  <div>I had asked - does your AOA indicator moves instantly with your =
elevator=20
  movement? Or is there lag.</div>
  <div>One interesting difference between Franz's AOA system and the =
simple vane=20
  display -- I see where you noted your AOA gage's digital numbers =
decreased=20
  when you held the airspeed constant at 120 kts. and moved the flaps =
from=20
  reflex to profile to 10 degrees down... and this I think seemed to you =
the=20
  opposite to what you expected... &nbsp;i.e increased lift from =
deploying a=20
  flap.</div>
  <div>But it is a correct indication, because you were holding the =
airspeed=20
  constant instead of holding the actual AOA constant. &nbsp;I think the =
reason=20
  it appears contra-intuitive is because</div>
  <div>Franz's "AOA" is not really an AOA that measures ANGLES, but =
measures=20
  pressure differential ... between upper and lower wing surface ... =
&nbsp;and=20
  compares that to -- and corrects for --- &nbsp; what he calls a "zero =
lift=20
  angle" (which one calibrates by flying a zero-G maneuver, and which =
moves and=20
  varies with each wing/flap configuration) and the pressure increment =
between=20
  the top and lower wing surface at an airspeed... all of which must be=20=

  calibrated. &nbsp;Pretty complicated.</div>
  <div><br></div>
  <div>A simple free-vane AOA just shows the angle between the actual =
relative=20
  wind and the wing's basic chord line, and has very angle-acurate marks =
on an=20
  indicator for the unchanging stall angle, and if desired, the angle =
one wants=20
  for approach, etc.&nbsp;</div>
  <div>I just made an angle scale behind the vane; others use a =
potentiometer=20
  shaft to mount the vane and read that out on a panel gage.&nbsp;</div>
  <div>I look with my eyeball at the AOA and my left hand on the stick =
adjusts=20
  the vane to read the desired angle during approach. &nbsp;</div>
  <div>Either way works; and what's important that with an AOA a pilot =
can see=20
  how close he is flying to his wing's stall angle -- or to its 'maximum =
lift=20
  angle' -- and avoid stalling.</div>
  <div><br></div>
  <div>Terry</div>
  <div><br></div>
  <div><br></div>
  <div><br></div>
  <div><br></div>
  <div><br></div>
  <div><br></div>
  <div><br>
  <div>
  <div>On Oct 28, 2011, at 3:43 PM, <a title=3D"mailto:Sky2high@aol.com" =
href=3D"mailto:Sky2high@aol.com">Sky2high@aol.com</a> wrote:</div><br =
class=3D"Apple-interchange-newline">
  <blockquote type=3D"cite">
    <meta name=3D"GENERATOR" content=3D"MSHTML 9.00.8112.16437">
    <div style=3D"FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 10pt" =
bottommargin=3D"7" leftmargin=3D"7" rightmargin=3D"7" =
topmargin=3D"7"><font color=3D"#000000" size=3D"2" face=3D"Arial">
    <div>Terrence,</div>
    <div>&nbsp;</div>
    <div>Thanks for the information.&nbsp; Of course you are right that =
the AOA=20
    is affected by the elevator loading up the wing.&nbsp; Other than =
that and=20
    the worthwhile&nbsp;EAA&nbsp;webinar that David pointed out, I can =
only=20
    report the following as "interesting" on my 320.&nbsp; I have rigged =
my=20
    ailerons to a slight up position to eliminate any wobble from =
lash.&nbsp;=20
    Because they are rigged up, the very minimal adverse yaw from =
aileron=20
    deflection (differential bell cranks) is further reduced because the =
down=20
    going aileron has to go further before it is down.&nbsp; Another=20
    factor&nbsp;that cannot be ignored is the eerie reflex flapped =
wings.&nbsp;=20
    They just don't quite perform the way&nbsp;presented in the EAA=20
    webinar.&nbsp;&nbsp;I have the original Jim Franz digital AOA device=20=

    (now&nbsp;Advanced Flight&nbsp;Systems)&nbsp;that utilizes the =
pressure=20
    differential betwixt the upper and lower wing along with =
pitot/static=20
    pressure (airspeed).&nbsp; Beside the fancy chevron, a 3 digit=20
    representation of the AOA is also displayed.&nbsp;&nbsp;The wing =
pressure=20
    pickups are located&nbsp;at the left wingtip.&nbsp; Today I went for =
a=20
    flight with the following results:</div>
    <div>&nbsp;</div>
    <div>My CG was at 25.5 (about 1.5" aft of most forward) at a TOW of =
about=20
    1540 lbs.</div>
    <div>At 6500 MSL (5800 Dalt) and&nbsp;3C OAT, I was indicating 180 =
KIAS (195=20
    KTAS), 24.8" MAP and 2480 RPM.</div>
    <div>&nbsp;</div>
    <div>At the 180 cruise:</div>
    <div>1. The AOA read 16 and 19 in either a right or left 20 degree =
level=20
    banked turn (I used the AP for this test).&nbsp;</div>
    <div>2. 1/2 rudder pushes does induce a slight roll with an AOA of =
18.&nbsp;=20
    If one does not attempt to hold level, the roll to the left also =
starts a=20
    dive (no surprise there).</div>
    <div>3.&nbsp; Cross controlled aileron induced 20 degree&nbsp;dutch =
rolls=20
    resulted in AOA&nbsp;readings of&nbsp;18-19.&nbsp; If the rudder was =
not=20
    used, the DG would swing about 10 degrees.</div>
    <div>&nbsp;</div>
    <div>At 120 KIAS (power appropriately back) and&nbsp;level flight =
with the=20
    ball centered:</div>
    <div>1. Flaps in reflex AOA =3D 42</div>
    <div>2. Flaps out of reflex (down 7 degrees) AOA =3D 27</div>
    <div>3. Flaps at take off position (about 10 degrees out of reflex) =
AOA =3D=20
    18</div>
    <div>Note that this is at variance with the webinar that claimed the =
AOA, as=20
    measured from chord line to relative wind, increased as flaps were=20=

    deployed.&nbsp; Not so by&nbsp;my AOA&nbsp;pressure =
measurements.&nbsp;=20
    Remember that the 200/300 Lancairs have a very strong pitching =
moment as the=20
    flaps are moved.&nbsp; In my case&nbsp;I required more&nbsp;up=20
    elevator&nbsp;as flaps were&nbsp;lowered and more power to overcome =
added=20
    drag and&nbsp;maintain level flight at the steady airspeed.</div>
    <div>&nbsp;</div>
    <div>At best glide (106 KIAS), flaps in full reflex:</div>
    <div>1. AOA =3D 58</div>
    <div>2. Left 1/2 rudder induced a roll, AOA =3D 62</div>
    <div>3. Right 1/2 rudder induced a roll, AOA =3D 64</div>
    <div>&nbsp;</div>
    <div>Level fight at a&nbsp;lower altitude&nbsp; in light chop saw =
the AOA go=20
    + or - 10</div>
    <div>&nbsp;</div>
    <div>On descent to the airport at 500 fpm and 135 KIAS, the AOA =
hovered=20
    around zero.</div>
    <div>&nbsp;</div>
    <div>I did not record data in the pattern as the tower asked that I =
keep=20
    ahead of the following jet.&nbsp; Besides, my short term memory is =
not up to=20
    the task of remembering multiple data points.</div>
    <div>&nbsp;</div>
    <div>Scott</div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>
    <div>In a message dated 10/27/2011 3:15:16 P.M. Central Daylight =
Time, <a title=3D"mailto:troneill@charter.net" =
href=3D"mailto:troneill@charter.net">troneill@charter.net</a> =
writes:</div>
    <blockquote style=3D"BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; =
MARGIN-LEFT: 5px"><font style=3D"BACKGROUND-COLOR: transparent" =
color=3D"#000000" size=3D"2" face=3D"Arial">Scott, Au contraire mon ami. =
&nbsp;=20
      <div>You saw my wing with its free-vane-type AOA, mounted at =
BL+47.=20
      &nbsp;</div>
      <div>In flight it is my trim tab that maintains the wing's AOA for =
each=20
      airspeed and tail loading (CG vs lift center), and only my light =
fingertip=20
      pressure make corrections for altitude/power).&nbsp;=20
      <div>This works in my bird in calm or gusty air.<br>
      <div>I haven't flown with one of the 'magic lights' or digital =
AOAs, but=20
      the results should be about the same as with my free-vane-type =
AOA.=20
      &nbsp;</div>
      <div>Watch your AOA, -<font class=3D"Apple-style-span" =
size=3D"4">hands=20
      off-,</font> in gusty or smooth air, zooming up or diving, and =
note that=20
      the AOA stays as trimmed.&nbsp;=20
      <div>
      <div>But with -<font class=3D"Apple-style-span" =
size=3D"4">&nbsp;hands=20
      on</font>&nbsp;- the stick, &nbsp;I am overriding the trim, and =
control of=20
      the wing's AOA, and it moves instantly with my stick movement, as =
if it=20
      were string-attached vane-to-stick. &nbsp;</div>
      <div>If your AOA doesn't react like that, it's got lag in the =
system.=20
      &nbsp;What kind of AOA do you have?</div>
      <div><br></div>
      <div>Operating near the stall, at high AOAs (regardless of =
airspeed) the=20
      wing's AOA is commanded by the stabilizer/elevator/trim unless =
overridden=20
      by the pilot ... who is responsible for his input.</div>
      <div>If he deliberately pulls the wing into a stall AOA, (which he =
can SEE=20
      on this AOA) he is deliberately giving away his pitch control. =
&nbsp;Then=20
      he has to use the elevator-stabilizer to reduce the wing's AOA. =
&nbsp;In=20
      the CAFE test of a 320/360 the pilot noted that the stall recovery =
was=20
      marginal. &nbsp;In a professional/military test pilot report at =
(<a title=3D"http://www.eaa1000.av.org/fltrpts/lanc360/hq.htm" =
href=3D"http://www.eaa1000.av.org/fltrpts/lanc360/hq.htm">www.eaa1000.av.o=
rg/fltrpts/lanc360/hq.htm</a>)=20
      &nbsp;gives the details regarding high and stall AOA and recovery =
of the=20
      small tail LNC2s, which prompted me to put slots on my horizontal=20=

      stabilizer. &nbsp;I wasn't sure how these tests applied to the =
235/320,=20
      but I thought -- close enough. &nbsp;The alternative was to be =
cautious=20
      about stalling the plane, and, to also be able to SEE how close I =
was to=20
      the stall AOA.</div>
      <div><br></div>
      <div>You mentioned &nbsp;steep turns to final. &nbsp;It is not the =
bank=20
      angle but the pulling back on the stick for a balanced turn that =
increases=20
      the AOA. &nbsp;I watch the AOA vane while pulling the wing into an=20=

      untrimmed AOA, but keep the AOA vane angle well below the marked =
stall=20
      AOA, (my tab trims only down to about 85 w/ gear down and flaps, =
rear CG)=20
      and the AOA responds just as though I had a string attaching the =
stick to=20
      the free vane. &nbsp;I keep about 5 degrees in reserve for a =
little extra=20
      lift needed to flare and slow to touchdown.&nbsp;</div>
      <div>&nbsp;</div>
      <div>When first flying with my homemade AOA (1970) while testing =
my O'=20
      Model W, I was delighted to be able to fly very close to the NACA =
4415's=20
      stall AOA and minimum airspeed with confidence, and thought I'd =
see if i=20
      could land right at the start of the runway and turn off at the =
run-up=20
      area... so when I got right down to the runway to flare and pulled =
back...=20
      there was no more CL at that high angle. &nbsp;Some airfoils have =
a=20
      gradual peak a little past the top of the lift curve, and I'd been =
flying=20
      in that max lift area. &nbsp;So I made a 'carrier landing' ... =
that is, I=20
      flew right into the concrete with a big bang.. &nbsp;Fortunately I =
had=20
      made the landing gear nice and strong. &nbsp;I got out and looked=20=

      everything over, and no damage, except to my ego. &nbsp;But I =
learned to=20
      respect the airfoil's gradual max lift peak, add reduced my AOA =
down to=20
      final.&nbsp;</div>
      <div>
      <div><br></div>
      <div>If (hands off) a plane wants to pitch up or down regardless =
of the=20
      pitch trim setting, &nbsp;then it is dangerously unstable because =
the CG=20
      is aft of the plane's lift center ... aft of where the CG is not =
supposed=20
      to be... unless you have artificial stabilization.</div>
      <div><br></div>
      <div>Regarding slowing in in chop or turbulence, I don't know what =
would=20
      cause that. Maybe some small zone on the plane is just a gentle =
enough=20
      curve that it is low drag unless bumped..? &nbsp;Some planes have =
a=20
      'bucket' of low drag in a narrow AOA range, and have to be flown =
fast=20
      enough to get the AOA down into the bucket at cruise power... but =
if=20
      approached slowly by setting the cruise power too early they don;t =
get up=20
      to speed. &nbsp;So the pilot leaves climb power on until he's in =
the=20
      bucket, and then can reduce power and stay there.</div>
      <div><br></div>
      <div>My comments are based on my own experience flying with my =
vane, in my=20
      Model W, in my Magnum Pickup, a Mitchell B-10 Wing, in &nbsp;a =
Dragonfly,=20
      a Challenger, and in the 235/320. &nbsp;</div>
      <div>I don't want to be stalled either. &nbsp;: )</div>
      <div><br></div>
      <div>Terrence<br>
      <div><br>
      <div>
      <div>
      <div>On Oct 27, 2011, at 10:08 AM, <a =
title=3D"mailto:Sky2high@aol.com" =
href=3D"mailto:Sky2high@aol.com">Sky2high@aol.com</a> wrote:</div><br =
class=3D"Apple-interchange-newline">
      <blockquote type=3D"cite">
        <meta name=3D"GENERATOR" content=3D"MSHTML 9.00.8112.16437">
        <div style=3D"FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: =
10pt" bottommargin=3D"7" leftmargin=3D"7" rightmargin=3D"7" =
topmargin=3D"7"><font color=3D"#000000" size=3D"2" face=3D"Arial">
        <div>Terrence,</div>
        <div>&nbsp;</div>
        <div>Yes, but the statement is too simple and is =
only&nbsp;true&nbsp;in=20
        smooth air under a constant load.&nbsp; The flying wing AOA =
(angle=20
        between wing and air flow)&nbsp;is not always under control of =
the=20
        pilot.&nbsp; Operating at an air speed&nbsp;near the stall AOA =
allows=20
        the wing to stall if the air is not smooth such as=20
        perturbations&nbsp;from turbulence (wake, wind shear, gusts, =
etc.)&nbsp;=20
        </div>
        <div>&nbsp;</div>
        <div>Pilot control is a component when operating near the stall =
AOA and=20
        loading up the wing without increasing the air flow =
that&nbsp;increases=20
        the AOA leading to a wing stall (i.e. low speed base to final=20
        turn&nbsp;where the bank angle is increased and the stick is=20
        pulled&nbsp;to line up with the runway on final).</div>
        =
<div>&nbsp;</div></font></div></blockquote></div></div></div></div></div><=
/div></div></div></div>=3D</font></blockquote></div></font></div></blockqu=
ote></div><br></div>=3D</font></blockquote></div></font></div></blockquote=
></div><br></div></body></html>=

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