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  #1  
Old 01-21-2020, 08:20 PM
sailvi767 sailvi767 is offline
 
Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,019
Default AOA confession

As a Navy trained pilot I have had AOA available in most aircraft I have flown. My first RV was a RV6 with AOA. I liked it but never had a occasion where I felt it provided any type of save or a warning that the aircraft was not in the state I wanted it at. Still I liked having the extra level of protection.
I purchased a F1 Rocket that did not have AOA or any stall warning. That bothered me a bit but I quickly found the aircraft to be very honest and easy to fly in the patten at the proper speeds. I had planned a panel upgrade shortly after purchasing it that would include AOA. In Nov when the aircraft was getting a new panel I considered dropping the AOA option to avoid a pitot change and cost. In the end I kept the AOA. (Dynon HDX system with Dynon pitot)
On Tuesday I was out flying after a frontal passage. On return to my home field which involves a slightly overshooting approach as the norm to avoid tall trees I needed to also compensate for a strong overshooting crosswind in the pattern. (30 Kts at 1000 ft). On base to final I found myself with more overshoot than planned and wrapping the turn up. Normally I would have been at 75 knots at this point but was actually targeting 80 knots with the bumpy conditions. Just after crossing the gap in the trees still turning to align with the runway at about 250 AGL I got a beep from the Dynon AOA. Unloaded, leveled the wings and went around. Glancing at the airspeed I was at 67 knots. In one G flight I get the first AOA beep at 56 Kts. I was slow, wrapped up and visually 100% outside watching the trees. I should have abandoned the approach prior to that point and gone around. I now embarrassingly have my first AOA save in 7 years of flying RV’s.
I don’t know how much margin was left but I am now very glad I went with the AOA option. I fell into a trap many pilots get into and needed the AOA tone to jolt me back into reality. Spend the money and put a AOA system into your aircraft!
George

Last edited by sailvi767 : 01-21-2020 at 08:23 PM.
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  #2  
Old 01-21-2020, 08:26 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,089
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Note that the stall warner that Van's sells is a singe-point AOA. It's intended for this sort of event.

Dave
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  #3  
Old 01-21-2020, 08:50 PM
mfleming's Avatar
mfleming mfleming is offline
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 416
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Great story. Iím also planning a glare shield mounted AoA display. Much more useful than the antiquated stall warner.
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Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Started 11/2016
Empennage completed 11/2016 (sans fiberglass)
Ailerons and flaps completed 3/2017.
Wings completed 12/2017 (sans fiberglass)
Started on QB fuselage 01/2018
Donated for 2019 and so should you
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  #4  
Old 01-21-2020, 09:03 PM
N546RV's Avatar
N546RV N546RV is online now
 
Join Date: Aug 2010
Location: Houston, TX
Posts: 856
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Quote:
Originally Posted by mfleming View Post
Great story. Iím also planning a glare shield mounted AoA display. Much more useful than the antiquated stall warner.
I'd love to have this, but unfortunately it's not an option with the Dynon system I'm going with. I suspect I'll make out fine with the progressive aural warning, but having that visual cue would still be a nice addition.
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-8 fuselage in progress (remember when I thought the wing kit had a lot of parts? HAHAHAHAHA)
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  #5  
Old 01-21-2020, 09:04 PM
gofly gofly is offline
 
Join Date: Apr 2019
Location: Cave Creek, AZ
Posts: 7
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Thanks for posting! Always great to hear others experiences. I too have an AOA going in my SuperSTOL.

Clark
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  #6  
Old 01-21-2020, 09:06 PM
Aflac01 Aflac01 is offline
 
Join Date: Jan 2020
Location: Lorena
Posts: 5
Default Speed

In a plane I fly for my job that has 3 different pitot tubes a pilot i work with managed to lose all 3 airspeed sources (it rained inside the hangar and water got inside the pitot lines and when they got above the freezing lvl all the lines froze solid) and ended up having to use their AOA as their only real way to tell airspeed. So I am very much with you on AOA being an important back up for multiple reasons.

I am new to the RV world (I am close to ordering my first kit). but in some planes ive flown you can also use AOA to fine tune best glide speed in an engine out situation, since in reality best glide will change with weight. though from what I have been told that change is minimal in an RV.
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  #7  
Old 01-21-2020, 09:28 PM
sailvi767 sailvi767 is offline
 
Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,019
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Quote:
Originally Posted by N546RV View Post
I'd love to have this, but unfortunately it's not an option with the Dynon system I'm going with. I suspect I'll make out fine with the progressive aural warning, but having that visual cue would still be a nice addition.
I really wish Dynon would offer a glareshield option. One thing I will add. With the first AOA tone coming on 6 knots above stall in my aircraft in 1 G flight I made it my SOP to do a immediate go around if I get a AOA tone and I am not in the flare 1 foot above the runway.
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  #8  
Old 01-21-2020, 09:42 PM
Paul from Flyleds's Avatar
Paul from Flyleds Paul from Flyleds is offline
 
Join Date: Apr 2016
Location: Melbourne, Australia
Posts: 156
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For those wanting a very neat glareshield AoA solution, start reading from post #20 in this thread.
Your wishes are soon to be answered.

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  #9  
Old 01-22-2020, 03:49 AM
Ed_Wischmeyer's Avatar
Ed_Wischmeyer Ed_Wischmeyer is online now
 
Join Date: May 2005
Location: Savannah, GA
Posts: 1,137
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Quote:
Originally Posted by sailvi767 View Post
On return to my home field which involves a slightly overshooting approach as the norm to avoid tall trees I needed to also compensate for a strong overshooting crosswind in the pattern. (30 Kts at 1000 ft). On base to final I found myself with more overshoot than planned and wrapping the turn up. Normally I would have been at 75 knots at this point but was actually targeting 80 knots with the bumpy conditions. Just after crossing the gap in the trees still turning to align with the runway at about 250 AGL I got a beep from the Dynon AOA. Unloaded, leveled the wings and went around. Glancing at the airspeed I was at 67 knots. In one G flight I get the first AOA beep at 56 Kts. I was slow, wrapped up and visually 100% outside watching the trees. I should have abandoned the approach prior to that point and gone around. I now embarrassingly have my first AOA save in 7 years of flying RV’s.
I don’t know how much margin was left but I am now very glad I went with the AOA option. I fell into a trap many pilots get into and needed the AOA tone to jolt me back into reality. Spend the money and put a AOA system into your aircraft!
George’s post, and the replies to it, show a wide range of responses with a similarly wide range of validity. (My qualifications to pontificate on the subject include four years of work as a contestant in the EAA Founder’s Innovation Prize on loss of control, and that work included studying 700 NTSB report narratives and dozens of dockets, watching a dozen accident videos over and over, flight tests and videos in my RV-9A, etc. All told, much more work and discovery than went into my Ph.D. from MIT… The result of all this is the Expanded Envelope Exercises (E3) so that pilots don’t lose their cognitive availability to process all of the information available when they get stressed. E3 has been written up a few times on line already.)

A number of points arise:
* Kudos! “Unloaded, leveled the wings and went around.” It doesn’t make a lot of difference in RVs with the abundant low speed control authority, but unloading the wings first before leveling is good form and can be crucial in other planes. Going around is good form;
* Hmm. “On base to final I found myself with more overshoot than planned and wrapping the turn up.” In the same way that going around is an under-practiced escape, so is tolerating a runway overshoot. Who says that overshooting a single runway is taboo? I used to train my primary students **NEVER** to tighten up the turn to final but to accept the overshoot and to learn from it and do better next time. And if there are closely space parallel runways, fly final at maybe 15° offset from the runway centerline for extra margin. Shucks, there are even ILS and localizer approaches with offset lateral guidance;
* One of the Extended Envelope Exercises is a deliberate runway overshoot to demonstrate that a strict psychological need to keep on the centerline at all costs can is a learned inappropriate reaction. Pilots tend to get comfortable on the centerline and, after a while, think that it is essential;
* Gusty winds can induce stalls. In my old Cessna, I once was flying with an extra 10 MPH in the pattern at an airport with known gusty conditions. Turning base in a shallow turn, the plane hit a gust and stalled. I did not hear the stall horn till after the recovery. Another man who posts here regularly had a similar experience. There are numerous examples in the literature where stressed pilots did not hear aural warnings…;
* Human factors – “visually 100% outside watching the trees.” This is one reason why visual AOA displays don’t live up to their promise. BTW, when this happens with even the fanciest head up displays (not heads up, please!), this phenomenon is called cognitive capture. Stressed pilots can spend so much attention on the outside world or on the symbology that the other gets ignored, even when watching both is essential;
* AOA limitation – All of the textbook illustrations of AOA at work assume that the AOA is constant. I did the flight test in the -9A (and presented at Oshkosh) that AOA can either lag (follow) pitch like airspeed does, or if there is a g load applied, AOA can lead pitch. Nobody talks about this, and nobody (that I know of) has researched the operational significance;
* I made a video of an approach and landing with winds 9G14. The AOA was all over the place and did not provide usable data all by itself. This is the same result as NASA report TN D-6210 from 1971 (!);
* Human factors – there are accident videos and multiple NTSB reports that indicate that lateral control and longitudinal control are separate tasks. This in turn suggests that problems turning base to final can be because the pilot was focusing on alignment and neglected pitch (and airspeed). The narrative above is consistent with this hypothesis. Interesting statistic: in 47% of the runway excursions on landing in RVs (running off the side of the runway after touchdown), the plane was first in trouble longitudinally, such as bounced landing, flat approach, etc;

I’ve now owned six airplanes in my career (four were RVs), and only the Cessna came with an aural stall warning system, a vane type. Haven’t really missed a stall warning system in any of 'em. When I was instructing in C150s, I really liked the vibrating reed stall warning with its progressive warning. When teaching slow flight and stalls, I’d tell the students to make the baby cry louder…

When I was rewiring the RV-9A and adding a Garmin autopilot and already had the wing open, that’s when I installed an AOA pitot tube. What did I learn?
* Visual AOA never got looked at in normal operation. And when I did look, just to see what it was showing, I had no frame of reference to know what it really meant when I had one or two or however many bars showing;
* It was a surprise to see that on a normal climbout, there were a few AOA bars showing.

Bottom line, and trying to keep it really short, get with a good CFI and learn to tolerate runway overshoots. Don’t be dying to avoid the overshoot. And don't count on some trendy gadget to save your bacon, because when you get really stressed, it will be just one more thing that gets ignored.
__________________
RV-9A at KSAV (Savannah, GA; dual experimental touch screens with autopilot, IFR GPS)
Previously RV-4, RV-8, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2020 dues slightly overpaid
Retired - "They used to pay me to be good, now I'm good for nothing."

Last edited by Ed_Wischmeyer : 01-22-2020 at 04:05 AM.
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  #10  
Old 01-22-2020, 04:04 AM
Capt Capt is offline
 
Join Date: Feb 2017
Location: Australia
Posts: 474
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Quote:
Originally Posted by Ed_Wischmeyer View Post
George’s post, and the replies to it, show a wide range of responses with a similarly wide range of validity. (My qualifications to pontificate on the subject include four years of work as a contestant in the EAA Founder’s Innovation Prize on loss of control, and that work included studying 700 NTSB report narratives and dozens of dockets, watching a dozen accident videos over and over, flight tests and videos in my RV-9A, etc. All told, much more work and discovery than went into my Ph.D. from MIT… The result of all this is the Expanded Envelope Exercises (E3) so pilots don’t lose their cognitive availability to process all of the information available. E3 has been written up a few times on line already.)

A number of points arise:
* Kudos! “Unloaded, leveled the wings and went around.” It doesn’t make a lot of difference in RVs with the abundant low speed control authority, but unloading the wings first before leveling is good form and can be crucial in other planes. Going around is good form;
* Hmm. “On base to final I found myself with more overshoot than planned and wrapping the turn up.” In the same way that going around is an under-practiced escape, so is tolerating a runway overshoot. Who says that overshooting a single runway is taboo? I used to train my primary students **NEVER** to tighten up the turn to final but to accept the overshoot and to learn from it and do better next time. And if there are closely space parallel runways, fly final at maybe 15° offset from the runway centerline for extra margin. Shucks, there are even ILS and localizer approaches with offset lateral guidance;
* One of the Extended Envelope Exercises is a deliberate runway overshoot to demonstrate that a strict psychological need to keep on the centerline at all costs can is a learned inappropriate reaction. Pilots tend to get comfortable on the centerline and, after a while, think that it is essential;
* Gusty winds can induce stalls. In my old Cessna, I once was flying with an extra 10 MPH in the pattern at an airport with known gusty conditions. Turning base in a shallow turn, the plane hit a gust and stalled. I did not hear the stall horn till after the recovery. Another man who posts here regularly had a similar experience. There are numerous examples in the literature where stressed pilots did not hear aural warnings…;
* Human factors – “visually 100% outside watching the trees.” This is one reason why visual AOA displays don’t live up to their promise. BTW, when this happens with even the fanciest head up displays (not heads up, please!), this phenomenon is called cognitive capture. Stressed pilots can spend so much attention on the outside world or on the symbology that the other gets ignored, even when watching both is essential;
* AOA limitation – All of the textbook illustrations of AOA at work assume that the AOA is constant. I did the flight test in the -9A (and presented at Oshkosh) that AOA can either lag (follow) pitch like airspeed does, or if there is a g load applied, AOA can lead pitch. Nobody talks about this, and nobody (that I know of) has researched the operational significance;
* I made a video of an approach and landing with winds 9G14. The AOA was all over the place and did not provide usable data all by itself. This is the same result as NASA report TN D-6210 from 1971 (!);
* Human factors – there are accident videos and multiple NTSB reports that indicate that lateral and longitudinal flight are separate tasks. This in turn suggests that problems turning base to final can be because the pilot was focusing on alignment and neglected pitch (and airspeed). The narrative above is consistent with this hypothesis. Interesting statistic: in 47% of the runway excursions on landing in RVs (running off the side of the runway after touchdown), the plane was first in trouble longitudinally, such as bounced landing, flat approach, etc;

I’ve now owned six airplanes in my career (four were RVs), and only the Cessna came with an aural stall warning system, a vane type. Haven’t really missed a stall warning system in any of 'em. When I was instructing in C150s, I really liked the vibrating reed stall warning with its progressive warning. When teaching slow flight and stalls, I’d tell the students to make the baby cry louder…

When I was rewiring the RV-9A and adding a Garmin autopilot and already had the wing open, that’s when I installed an AOA pitot tube. What did I learn?
* Visual AOA never got looked at in normal operation. And when I did look, just to see what it was showing, I had no frame of reference to know what it really meant when I had one or two or however many bars showing;
* It was a surprise to see that on a normal climbout, there were a few AOA bars showing.

Bottom line, and trying to keep it really short, get with a good CFI and learn to tolerate runway overshoots. Don’t be dying to avoid the overshoot. And don't count on some trendy gadget to save your bacon, because when you get really stressed, it will be just one more thing to get ignored.

Well said Ed The critical word to take away from all that is "unloading", few understand that.
I've got an AoA in my 8, a set of vertical lights on the panel, I didn't put it there (bought the plane built) I've never really looked at it much and sure as h ell would never rely on it! My whole attention is devoted to one single guage inside my plane when landing, the ASI, the rest of my attention is outside. Even flying the early Lears many years ago my head was on a swivel between the ASI and the outside cues despite a crude AoA on the glare shield.
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