What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Considerations with AoA

H

humptybump

Well Known Member
I just watched a video on AoA (https://youtube.com/watch?v=8JcjWnAJGKQ). While very dry, it made me evaluate my own installation.

My system uses the pressure differential design with a pitot tube having both pitot and AoA plumbing. I do not have a dedicated display. I use the AoA which is rendered on my EFIS. My AoA system uses tones to indicate the approach to an excess AoA condition. My system has only a single set of calibration points. I calibrated with flaps deployed.

My experience has been I never see the AoA indication when landing. I typically hear the tone but not until I've already touched down or so close to touch down that no pilot actions would be expected.

I could change calibration is be more cautious and conservative.

Since the AoA is designed to indicate prior to any audable indication, I am not aware of any visual cues which would benefit my flight or improve safety.

I could add a remote AoA display on top of the glare shield.

The above is not intended for suggestions for me. I know what I have and I know what I may to do to change my system if I choose. My intent is to provide a point of reference for others to evaluate their AoA system experience as well as to provide one set of data for those considering AoA for their aircraft or build.
 
Last edited:
HB,
Great point to consider.
I for one love the dual-line AOA in my SkyView. I, too, don't often actually look at the AOA indication in practice, but the tones are hugely valuable to me. I believe I incorporate those tones into my crosscheck because of my background flying F-4 Phantoms. Phantom pukes are children of the AOA tone. In the F-4E, F, and G models (my back-in-the-day livery), we flew AOA and AOA tones throughout the operating envelope, particularly during high-G or max-AOA turns (25 units AOA) and during approaches and landings (17 units or 19.2 units AOA, depending on configuration and planned speed). Above 25 units, the slatted F-4 wing stalled. BTW, don't ask me how many degrees of AOA a "unit" is: Only the MacD engineers knew, not us captains. The AOA tone was vital to our crosscheck.
Fast forward to my RV-7A. I have the tones calibrated to reach stall beeper just before the actual stall break. This works for my approaches (usually at flaps 20) and in accelerated flight. I can't adjust it for flap configuration without doing a complete recalibration, but I get the critical AOA beeper just a degree or two before reaching critical AOA.
Bottom line: Pick what works. I recommend you recalibrate to the conservative side. That setup works well for me.
 
Last edited:
I am planning to use the Dynon pitot/AOA as well but my wings were mostly built by another and the right wing has a different system installed already with a hole on top and bottom for measuring pressure differential.


My questions:
1. Which system is better?
2. Should I consider using both?
 
Our's are all calibraetd to provide start beeping at normal approach speed Glen - the first level of beep, just to let you know you are on speed. They reach teh steady tone phase at the stall. The tones are primary, the glareshield displays are seconday, and the EFIS displays are tertiary (and mostly useless becasue they are out of sight).

Flying the approach with a nice steady slow beep let's you know that the system is working and that you have lots of margin. When it gets frantic, you know you are close to stall. ANd your eyes stay outside the cockpit all the time.
 
You might consider activating and testing one at a time, then both at the same time, and see which set-up you like best. If I had both on at the same time but they gave conflicting information that I couldn't synchronize through settings/configuration, while, that constitutes a data point. I'd know to pick one or the other and desengage/remove the worse system. Might not be the streamlined method (have you seen me? I'm not exactly streamlined :D ), but it is a method.
 
Ironflight said:
... The tones are primary...and the EFIS displays are tertiary (and mostly useless becasue they are out of sight).

Flying the approach with a nice steady slow beep let's you know that the system is working and that you have lots of margin. When it gets frantic, you know you are close to stall. ANd your eyes stay outside the cockpit all the time.
Click to expand...

Precisely.
 
Ironflight said:
Our's are all calibraetd to provide start beeping at normal approach speed Glen - the first level of beep, just to let you know you are on speed. They reach teh steady tone phase at the stall. ...
Click to expand...
I've been trying to set mine up that way as well but haven't found a good way to make that happen other than trial and error Skyview re-calibrations. How did you get yours calibrated like you wanted?
 
tomkk said:
I've been trying to set mine up that way as well but haven't found a good way to make that happen other than trial and error Skyview re-calibrations. How did you get yours calibrated like you wanted?
Click to expand...

I have the same question.
 
tomkk said:
I've been trying to set mine up that way as well but haven't found a good way to make that happen other than trial and error Skyview re-calibrations. How did you get yours calibrated like you wanted?
Click to expand...

I haven't had a chance to fly the Skyview in the Tundra we're getting close to finishing (we've put a three-screen Skyview in that to learn more about the system), so I haven't had a chance to do a Skyview AoA calibration yet.

The Garmin G3X calibration wizard is outstanding and walks you through the process in a simple manner.

Calibrating the stand-alone AoA Pro from AFS is also simple to get it right where you want it, but it doesn't have vairable tones - just an audio warnignwhen you get to the limit ("Angle, Angle Push!!"). But their glareshield-mounted display is excellent.
 
Ironflight said:
Calibrating the stand-alone AoA Pro from AFS is also simple to get it right where you want it, but it doesn't have vairable tones - just an audio warnignwhen you get to the limit ("Angle, Angle Push!!"). But their glareshield-mounted display is excellent.
Click to expand...


I prefer listening to Jenny telling me to push over tones any day. :D

I tend to keep looking at the AOA out of the corner of my eye during the scan to see the various colors. If I don't see any green or yellow, I know I'm in trouble.
 
tomkk said:
I've been trying to set mine up that way as well but haven't found a good way to make that happen other than trial and error Skyview re-calibrations. How did you get yours calibrated like you wanted?
Click to expand...

I just followed the Skyview AOA calibration wizard in flight. However, instead of taking it all the way to the stall break, I released the stick back-pressure just before the stall and simultaneously pushed the "stall" hot key. I did that several times. Then, after completing the wizard and testing the AoA readings and tone with more stalls, I was happy with the settings: It gives me full stall indications and tone beeper just before the wing actually stalls. That's how I want it: On the conservative side. I want a pre-stall warning, not a post-stall notification.
 
I have the AOA display in my AFS 4500 system, and my experience with it is quite positive.

While I would prefer a tone of changing pitch as I got closer to the stall over the "Angle Angle Push Push" that I get at a pretty conservative point before stall, I actually look at the display quite often. Whenever I'm in a climb, steep turn or both while near the ground, I grab a quick peek at the display to see where I'm at lift wise. It's always comforting to know that even though I feel I might be getting close, I still have a lot of "reserve" left.

Well worth the money spent in my book.
 
Paul - have you tried the AoA tone output from the GRT HX in the Val? I haven't tried it yet but that might help with an audio tone to augment the Angle Angle Push.
 
scrollF4 said:
I just followed the Skyview AOA calibration wizard in flight. However, instead of taking it all the way to the stall break, I released the stick back-pressure just before the stall and simultaneously pushed the "stall" hot key. I did that several times. Then, after completing the wizard and testing the AoA readings and tone with more stalls, I was happy with the settings: It gives me full stall indications and tone beeper just before the wing actually stalls. That's how I want it: On the conservative side. I want a pre-stall warning, not a post-stall notification.
Click to expand...

I like this approach. I'd rather have a tone in my ear saying "getting warmer" "getting warmer" "getting hot" "HOT" than having to look at a display. Especially on landing, I'd like to have my eyes outside and let the bird talk to me rather than glancing at the ASI every few seconds...
 
scrollF4 said:
I just followed the Skyview AOA calibration wizard in flight. However, instead of taking it all the way to the stall break, I released the stick back-pressure just before the stall and simultaneously pushed the "stall" hot key. I did that several times. Then, after completing the wizard and testing the AoA readings and tone with more stalls, I was happy with the settings: It gives me full stall indications and tone beeper just before the wing actually stalls. That's how I want it: On the conservative side. I want a pre-stall warning, not a post-stall notification.
Click to expand...
Thanks. Yeah, that's what I've been doing too, I just haven't quite found the right spot that makes me happy yet.
 
AOA recommendations

I'm planning my panel and electrical. I have a GRT Sport EFIS. Can anyone give me recommendations of what is the best AOA to get?....and reasons why?

Thanks......
 
Happier AoA user

I reviewed the calibration described by Paul and compared it to the documentation for my particular system. It became a case of "book knowledge" vs "practical knowledge". The "book" says to calibration the initial caution warning at appropriately 10% above stall. The "practical" setup, as described by Paul, is to have the caution warning start very close to your final approach speed.

I moved the initial display of my AoA to be closer to my "fast approach" speed.
I moved the initial tone to be 2kts above my desired approach speed for my field. **

The new settings have the initial gentle beep start as I get to that optimal speed I am looking for.


Eureka

It reminded me so much of my initial training. The slow beeps were like my old flying instructor say "OK", "your'e doing fine", "keep it steady". If the beeps stopped it is like the instructor saying "you are a bit fast". If the beeping accelerated my old instructor would have been saying "you're getting slow", "watch the nose", "keep your speed up".

Following the callibration change, the first landing back at my field was coming in over 75' trees, with a sinker 1/4nm out, and winds were gusting 12-24kts 60-80 degree across cross the runway. These conditions usually result in a "firm landing" or rolling long (and have been a go-around more than once). Today it was a smooth flare, very little braking, and a back taxi well before the end. Future flights will validate the new settings and I expect I'll find the AoA to be more useful going forward.


** I fly into a lot of 2000ft (or less) grass strips with a wide array of obstacles so my typical approach speed is measurable less than if I were landing at KDOV or KBXM (two interesting landings for those who have not had the pleasure).
 
I installed the Dynon FlightDEK 180 system in my RV8 with it's integrated AOA. I set up the system per the Dynon directions and find that the system is bang on for all the aircraft configurations. The AOA is displayed in the lower left corner of the screen and has an audible tone. I find that I rarely look at the display. The tone generator is very good and I find that to be all I desire. I don't have any desire at this point to install any dedicated display above the panel as typically I find that it is more important to look at what is going on outside the aircraft.
 
Berchmans said:
I installed the Dynon FlightDEK 180 system in my RV8 with it's integrated AOA. I set up the system per the Dynon directions and find that the system is bang on for all the aircraft configurations. The AOA is displayed in the lower left corner of the screen and has an audible tone. I find that I rarely look at the display. The tone generator is very good and I find that to be all I desire. I don't have any desire at this point to install any dedicated display above the panel as typically I find that it is more important to look at what is going on outside the aircraft.
Click to expand...

I'm very glad to hear that. I have a D180 in the RV-12 I just recently started flying, and adding AOA is on my to-do list. Reading through the installation manual it seems like it will do just what I want; it's good to see some confirmation of that.
 
scrollF4 said:
I just followed the Skyview AOA calibration wizard in flight. However, instead of taking it all the way to the stall break, I released the stick back-pressure just before the stall and simultaneously pushed the "stall" hot key.
Click to expand...

Just a note, you don't have to press the stall key at the same time. The logic is that it looks for the highest AoA encountered during the times between each STALL press. So if you don't get all the way to the stall and back off, it will see that peak just fine even if you wait until you're fully recovered to press it.

Otherwise, not getting all the way to the stall if you want some overhead works great. Also, remember that in the audio settings, you can choose where the audio starts, so you do have some adjustments to make it come on earlier even if you have the red line set at a full stall.
 
I have a Dynon Skyview and find myself tuning out the AOA tone unless I really concentrate. I also find myself glancing at airspeed on approach because the AOA display on the Skyview is just too small and hard to find...

I really wish that Dynon would come out with an vertical AOA display that cold be mounted on the glare shield so that it could be referenced without taking my eyes off the landing picture out front...

To me, something similar to the Garmin one would be much more helpful and harder to ignore...

 
If you can tune out the tone, I'd suggest you make it a lot louder.
The dash mounted displays still have an issue - they're out of focus when you look at the runway, and vice versa.
 
Ron RV8 said:
I have a Dynon Skyview and find myself tuning out the AOA tone unless I really concentrate. I also find myself glancing at airspeed on approach because the AOA display on the Skyview is just too small and hard to find...

I really wish that Dynon would come out with an vertical AOA display that cold be mounted on the glare shield so that it could be referenced without taking my eyes off the landing picture out front...

To me, something similar to the Garmin one would be much more helpful and harder to ignore...

Click to expand...


Dynon does have a glare shield AOA. It's produced by AFS. You can get the standalone unit. Unfortunately, there isn't integration with Skyview that I'm aware as of yet.
 
Since the Dynon already has AOA, it would be really nice to have a compatible, (reasonably priced), glare shield annunciator available to display the information.

Since I already have AOA, I really do not want to go out and purchase a whole new system...

If I can visually focus on airspeed, I can probably focus on AOA within my field of vision...
 
Last edited:
Ron RV8 said:
If I can visually focus on airspeed, I can probably focus on AOA within my field of vision...
Click to expand...

Right on, Ron. Finally some common sense. What you are suggesting is exactly what I do and it has worked well for the 7 years my RV-7 has been flying. Many seem to dismiss the panel mounted units as useless. No doubt a glare shield mounted system is better but AOA on the EFIS is a very good tool. I'm still old school and haven't totally given up the airspeed indication but I cross check it with the AOA several times at different legs of the pattern, especially if I'm near gross weight. It is no different than glancing at the altimeter or any other instrument. That's the beauty of AoA... one glance, requiring no mental gymnastics and you know exactly where you stand. Once I'm over the fence I transition almost totally to the "outside the cockpit" environment. If I were building again I'd go for the glare shield unit, but what I have is satisfactory for the way I use the airplane. At some point everyone has to decide what is good enough for themselves before going totally broke buying all the latest gizmos.
 
Skyview AOA

I may be showing my ignorace here but someone please explain.
Stall occurs at the same AOA right?
But
Doesn't AOA change when the chord changes (flap deployment)?
So
Does the Skyview get calibrated for one condition such as partial flaps landing? What about all the other configurations from no flaps to full flaps?
 
Hi Larry, different vendors' systems have different logic and calibration.

Some systems calibrate and store data for more than one "configuration". Typically, these systems store one set of data for "clean" and one for "dirty". They require a sensor to know the aircraft configuration - eg a flap position sensor.

Some systems store a single set of internal data based on one or more configuration cycles. With a system like this, I would choose to calibrate for the more likely critical scenario - which for me is the is landing configuration.
 
Quick update

I've been flying recently with my AoA recalibrated using Paul's suggestion.

It is working very well for me. Recently I was flying into a grass strip and here is what I experienced:
  • I didn't initially spot the field so I circled
  • when I spotted the field, I was near the approach end and 1200' above
  • I turned out on downwind, deployed flaps, and pulled the throttle
  • I made a relative steep bank to base at 1.6x of stall
  • while my AoA gently beeped (not a Beatles lyric)
  • I turned to final and slowed until the AoA just started to beep
  • with the gentle beep I had no need to 'glance' into the cockpit
  • just before the flare I slowed to a quicker beep
  • landed 3-point with short roll

Later, when discussing the landing the consensus was I had a steeper approach angle; the plane landed in a clean 3-point; there was no bounce and a noticeable short roll. This exactly describes the type of landing I look for on short grass runways.

At the end of the day, landing back at my own field, I had a strong crab to compensate for the crosswind and I was coming in over 75' trees and between the 'gut'. My landing was similar but I transitioned into an initial touch down was a tail-low wheel landing.

My conclusion: the AoA initial alert set to my [relative] slow approach speed is a good configuration for me.

Thanks Paul !
 
You must log in or register to reply here.
Back
Top