X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 31 Oct 2011 09:04:18 -0400 Message-ID: X-Original-Return-Path: Received: from mta11.charter.net ([216.33.127.80] verified) by logan.com (CommuniGate Pro SMTP 5.4.2) with ESMTP id 5177768 for lml@lancaironline.net; Sat, 29 Oct 2011 12:59:25 -0400 Received-SPF: pass receiver=logan.com; client-ip=216.33.127.80; envelope-from=troneill@charter.net Received: from imp09 ([10.20.200.9]) by mta11.charter.net (InterMail vM.8.01.05.02 201-2260-151-103-20110920) with ESMTP id <20111029165850.GWUF4019.mta11.charter.net@imp09> for ; Sat, 29 Oct 2011 12:58:50 -0400 Received: from [192.168.1.100] ([75.132.241.174]) by imp09 with smtp.charter.net id qgyp1h00L3mUFT705gyptE; Sat, 29 Oct 2011 12:58:50 -0400 X-Authority-Analysis: v=1.1 cv=6DnK9SlspjQUafU6MzYmZAt1wpB1MUaNH28Mo/Kfxqk= c=1 sm=1 a=VBY9H4zE2BIA:10 a=yUnIBFQkZM0A:10 a=VxlS/kh5Y2KhHY/Xui1ATg==:17 a=3oc9M9_CAAAA:8 a=hOpmn2quAAAA:8 a=xMGpOozMAAAA:8 a=nLHdN8KDsmzHivwPFM0A:9 a=UNce9sGfB_8FH7AS7h0A:7 a=CjuIK1q_8ugA:10 a=U8Ie8EnqySEA:10 a=hUswqBWy9Q8A:10 a=MJllL-gu5e31BcAb:21 a=f6U74mnjVikSiOWJ:21 a=ixH0jP6Sh26X-uf1mP0A:9 a=kx06pyp3_9RAA9BhrT4A:7 a=RhAnTGPKbOYA:10 a=gTt9TlXs2RwA:10 a=VxlS/kh5Y2KhHY/Xui1ATg==:117 From: Terrence O'Neill Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-158-150429735 Subject: Re: [LML] Re: Fw: Updated SUMMARY OF LANCAIR ACCIDENTS IN NTSB DATABASE X-Original-Date: Sat, 29 Oct 2011 11:58:49 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <3898272A-33B3-423E-B1E5-BB3A8FC6BD07@charter.net> X-Mailer: Apple Mail (2.1084) --Apple-Mail-158-150429735 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Scott, 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.) 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 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. 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. 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. Terry =20 On Oct 28, 2011, at 3:43 PM, Sky2high@aol.com wrote: > 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 --Apple-Mail-158-150429735 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

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. 
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. 
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.  
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.

Terry






 <= br>
On Oct 28, 2011, at 3:43 PM, Sky2high@aol.com wrote:

Terrence,
 
Thanks for the information.  Of course you are right that the = AOA is=20 affected by the elevator loading up the wing.  Other than that and = the=20 worthwhile EAA webinar that David pointed out, I can only = report the=20 following as "interesting" on my 320.  I have rigged my ailerons to = a=20 slight up position to eliminate any wobble from lash.  Because they = are=20 rigged up, the very minimal adverse yaw from aileron deflection = (differential=20 bell cranks) is further reduced because the down going aileron has to go = further=20 before it is down.  Another factor that cannot be ignored is = the eerie=20 reflex flapped wings.  They just don't quite perform the = way presented=20 in the EAA webinar.  I have the original Jim Franz digital AOA = device=20 (now Advanced Flight Systems) that utilizes the pressure=20= differential betwixt the upper and lower wing along with pitot/static = pressure=20 (airspeed).  Beside the fancy chevron, a 3 digit representation of = the AOA=20 is also displayed.  The wing pressure pickups are = located at the=20 left wingtip.  Today I went for a flight with the following = results:
 
My CG was at 25.5 (about 1.5" aft of most forward) at a TOW of = about 1540=20 lbs.
At 6500 MSL (5800 Dalt) and 3C OAT, I was indicating 180 KIAS = (195=20 KTAS), 24.8" MAP and 2480 RPM.
 
At the 180 cruise:
1. The AOA read 16 and 19 in either a right or left 20 degree level = banked=20 turn (I used the AP for this test). 
2. 1/2 rudder pushes does induce a slight roll with an AOA of = 18.  If=20 one does not attempt to hold level, the roll to the left also starts a = dive (no=20 surprise there).
3.  Cross controlled aileron induced 20 degree dutch = rolls=20 resulted in AOA readings of 18-19.  If the rudder was not = used,=20 the DG would swing about 10 degrees.
 
At 120 KIAS (power appropriately back) and level flight with = the ball=20 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=20 18
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.  Not so by my AOA pressure measurements.  = Remember=20 that the 200/300 Lancairs have a very strong pitching moment as the = flaps are=20 moved.  In my case I required more up elevator as = flaps=20 were lowered and more power to overcome added drag = and maintain level=20 flight at the steady airspeed.
 
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
 
Level fight at a lower altitude  in light chop saw the = AOA go +=20 or - 10
 
On descent to the airport at 500 fpm and 135 KIAS, the AOA hovered = around=20 zero.
 
I did not record data in the pattern as the tower asked that I keep = ahead=20 of the following jet.  Besides, my short term memory is not up to = the task=20 of remembering multiple data points.
 
Scott
 
 
 
In a message dated 10/27/2011 3:15:16 P.M. Central Daylight Time,=20= troneill@charter.net = writes:
Scott,=20 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=20 airspeed and tail loading (CG vs lift center), and only my light = fingertip=20 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=20 results should be about the same as with my free-vane-type AOA. =  
Watch your AOA, -hands = off-,=20 in gusty or smooth air, zooming up or diving, and note that the AOA = stays as=20 trimmed. =20
But with - hands=20= on - the stick,  I am overriding the trim, and = control of the=20 wing's AOA, and it moves instantly with my stick movement, as if it = were=20 string-attached vane-to-stick.  
If your AOA doesn't react like that, it's got lag in the system.=20=  What kind of AOA do you have?

Operating near the stall, at high AOAs (regardless of airspeed) = the=20 wing's AOA is commanded by the stabilizer/elevator/trim unless = overridden by=20 the pilot ... who is responsible for his input.
If he deliberately pulls the wing into a stall AOA, (which he can = SEE on=20 this AOA) he is deliberately giving away his pitch control.  Then = he has=20 to use the elevator-stabilizer to reduce the wing's AOA.  In the = CAFE=20 test of a 320/360 the pilot noted that the stall recovery was = marginal.=20  In a professional/military test pilot report at (www.eaa1000.av.o= rg/fltrpts/lanc360/hq.htm)=20  gives the details regarding high and stall AOA and recovery of = the small=20 tail LNC2s, which prompted me to put slots on my horizontal = stabilizer.=20  I wasn't sure how these tests applied to the 235/320, but I = thought --=20 close enough.  The alternative was to be cautious about stalling = the=20 plane, and, to also be able to SEE how close I was to the stall = AOA.

You mentioned  steep turns to final.  It is not the = bank angle=20 but the pulling back on the stick for a balanced turn that increases = the AOA.=20  I watch the AOA vane while pulling the wing into an untrimmed = AOA, but=20 keep the AOA vane angle well below the marked stall AOA, (my tab trims = only=20 down to about 85 w/ gear down and flaps, rear CG) and the AOA responds = just as=20 though I had a string attaching the stick to the free vane.  I = keep about=20 5 degrees in reserve for a little extra lift needed to flare and slow = to=20 touchdown. 
 
When first flying with my homemade AOA (1970) while testing my O' = Model=20 W, I was delighted to be able to fly very close to the NACA 4415's = stall AOA=20 and minimum airspeed with confidence, and thought I'd see if i could = land=20 right at the start of the runway and turn off at the run-up area... so = when I=20 got right down to the runway to flare and pulled back... there was no = more CL=20 at that high angle.  Some airfoils have a gradual peak a little = past the=20 top of the lift curve, and I'd been flying in that max lift area. =  So I=20 made a 'carrier landing' ... that is, I flew right into the concrete = with a=20 big bang..  Fortunately I had made the landing gear nice and = strong.=20  I got out and looked everything over, and no damage, except to = my ego.=20  But I learned to respect the airfoil's gradual max lift peak, = add=20 reduced my AOA down to final. 

If (hands off) a plane wants to pitch up or down regardless of = the pitch=20 trim setting,  then it is dangerously unstable because the CG is = aft of=20 the plane's lift center ... aft of where the CG is not supposed to = be...=20 unless you have artificial stabilization.

Regarding slowing in in chop or turbulence, I don't know what = would cause=20 that. Maybe some small zone on the plane is just a gentle enough curve = that it=20 is low drag unless bumped..?  Some planes have a 'bucket' of low = drag in=20 a narrow AOA range, and have to be flown fast enough to get the AOA = down into=20 the bucket at cruise power... but if approached slowly by setting the = cruise=20 power too early they don;t get up to speed.  So the pilot leaves = climb=20 power on until he's in the bucket, and then can reduce power and stay=20= there.

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  a = Dragonfly, a=20 Challenger, and in the 235/320.  
I don't want to be stalled either.  : )

Terrence

On Oct 27, 2011, at 10:08 AM, Sky2high@aol.com wrote:

Terrence,
 
Yes, but the statement is too simple and is = only true in=20 smooth air under a constant load.  The flying wing AOA (angle = between=20 wing and air flow) is not always under control of the = pilot. =20 Operating at an air speed near the stall AOA allows the wing to = stall=20 if the air is not smooth such as perturbations from turbulence = (wake,=20 wind shear, gusts, etc.) 
 
Pilot control is a component when operating near the stall AOA = and=20 loading up the wing without increasing the air flow = that increases the=20 AOA leading to a wing stall (i.e. low speed base to final = turn where=20 the bank angle is increased and the stick is pulled to line up = with the=20 runway on final).
=
 
<= /div>
=3D

= --Apple-Mail-158-150429735--