Fine-tuning AOA

[jc2da]

AOA is not very useful to me at the moment. I would like to change some things and am wondering if it is possible.

For one, is there a way to reset previous AOA calibration data? Basically, i would like to start the calibration all over again.

Specifically, the AOA calibration instructions want you to do a stall in a "cruise" configuration, which I interpreted to mean no-flaps. However, that gives me the highest nose-high attitude. Thus, in a flare with flaps, I do not get any aural warning of AOA, not even close.

If I were to do the AOA calibration all over again, I would only calibrate for a full flap configuration. AOA warning in cruise configuration is much less useful to me than in a landing configuration. I am thinking then I might get more of an aural AOA warning when it is most needed, during landings.

Any feedback is appreciated!
Jae

 

[dynonsupport]

When you finish a new calibration, it completely overwrites the previous one.

The AOA does not distinguish between flaps up and flaps down configurations, you're right. But think about it in the raw terms: The full AOA bar is the AOA that is demonstrated during the cruise portion of the calibration. The empty AOA bar is what is demonstrated in the stall that you perform with the highest perceived AOA. In some airplanes, the perceived AOA (as far as the AOA/pitot can see) may differ between a clean and dirty configuration, and this can cause the clean configuration critical AOA to be reached before the dirty configuration, and that would cause a pre-mature onset of the warning when you're dirty, as you're experiencing.

Your hunch is exactly right though. Recalibrate, using the clean cruise configuration for the low AOA part of the cal, and then do just a single stall, in landing configuration, with power off (ie, a simulated landing) to set the critical AOA. This will give you better AOA information at landing, possibly at the expense of worse information at high AOA when clean.

 

[jc2da]

Thanks for the response. I am still trying to test out the functionality to see if I can get it "calibrated" the way I want. My testing so far does look like it's going in the right direction.

I got one day of testing in but it was 15G24 (low pressure cold front) or so with winds 180deg from its usual direction. Thus, I never got to test to my satisfaction. Will report in again.

Thanks!
Jae

 

[swatson999]

You really ought to change this so that the system can take an input from a flap position sensor (even up v down would be better than nothing) and can give the *correct* AOA for both configurations.

Without this, one of the other is always going to be wrong.

Seems relatively simple to do...why the resistance?

 

[jc2da]

I got to test in some better conditions. The AOA now will give me an aural warning if i get too slow and squirrelly on my approach, flare, and landing. I think it's a great feature that I am finally able to utilize better. I have no formal training on the use of AOA, so I will need to do more research. To me it works as a finer resolution stall warning indicator as opposed to my traditional stall warning indicator which operates as a binary on/off switch. It's just another piece of information to practice and utilize on landing.

My 2c worth!
Jae

 

[MCRider]

Are there any plans to consider the flaps position for the AOA display / audible warning in future software versions? If yes, I would connect the flap position potentiometer the next time the EMS box and the cabling are accessible. Otherwise I could save myself the work (flap position can easily be checked by looking left or right)...

 

[dynonsupport]

It's something we have considered, but I don't have a time frame for you on when we might do it.

 

[MCRider]

Thanks for the information.

 

[swatson999]

Perhaps AFS can help you add this feature. They seem to have figured it out.

Seriously, this is weak...the critical angle is *different* depending upon flap configuration, and anything less than accounting for *at least* full up or full down flaps is just lame (not to mention potentially dangerous).

 

[dynonsupport]

We've been selling AoA systems for over a decade now, and while this does come up now and then, it's not a demand as large as other things that we have prioritized and have been working on.

Safety is not the issue. If you calibrate the Dynon AoA as the manual indicates, it will always indicate the stall at or before the real stall, for any configuration. Thus, you do not end up with a configuration that allows you to stall without an indication. The worst you have is an indication earlier than the stall.

I would like to point out that the Alpha Systems AoA, the new Bendix King KLR 10, and the Garmin G3X all do AoA, and none of them factor in the flaps. It's cool that AFS does, but they are an outlier in that area for now. It's still something we want to do too. The only issue to doing this is one of having a huge list of requested features and prioritizing them. We know how to do it, it is not an issue of a technical knowledge deficiency (even before AFS was part of our team).

 

[marchudson]

I know there is a difference in critical AOA between flaps down and flaps up. I've flown several aircraft that had a large change in AOA when configuring and they account for it. I was concerned about this at first but, I'm just not seeing it in the RV-7 that I fly. Jae I'm not sure if the RV-10 exhibits a large change is AOA as you put the flaps down. I would say that when you do recalibrate the AOA, make sure it is in very smooth air and that you are smooth with the controls. I've tried to notice a difference on the AOA gauge when stalling clean and dirty and just can't do it, at least not in the RV-7.

Hope this helps
Marc

 

[Juvat]

Guys, I'm perfectly satisfied with how Dynon has set up their AOA. Remember, an AOA indicator is an approach to stall indicator, *not* a stall indicator. The beeping from the AOA indicator is telling you that you are approaching the critical angle of attack and that you should do something about it. If I have some flaps out and it happens to warn me 2 or 3 knots early, then that's a good thing! It's doing its job just fine.

 

[ljpappas]

I have been looking at the AOA indicator on the HDX/Skyview and comparing it to the Advanced flight Systems version. It seems to me that the addition of what Advanced calls the "donut" in the middle of the display is superior to Dynon's display, in that it gives an easy visual reference for lining up the bars for the approach.

How about making that change to the Dynon display? PS, a glareshield mounted remote indicator would also be great!!

 

[shenweas]

I played with the AOA tuning for a long time and finally arrived with the calibration that works great for me. If I keep increasing AOA until I have a steady tone with power at idle, then there is not quite enough energy to flare. I can either maintain that AOA and give a slight burst of power just before touchdown or if I want to flare without power I have to adjust my AOA on the decent to something more like a slow to moderate beep pattern. One thing I have observed is that after flying this airplane and system for over 1100hrs, I can tell there is about a 1 second delay in the AOA indicator and tone. I have gotten used to it but would be nice if there was a way for it to have a quicker response.

 

[tomkk]

I played with the AOA tuning for a long time and finally arrived with the calibration that works great for me.  If I keep increasing AOA until I have a steady tone with power at idle ...

How did you "fine tune" your AOA? What do you mean when you say "keep increasing AOA"? I've tried adjusting the configuration and speed at which I declared a "stall" in the AOA cal procedure but have yet to find a combination that I like.

 

[shenweas]

I played with the AOA tuning for a long time and finally arrived with the calibration that works great for me.  If I keep increasing AOA until I have a steady tone with power at idle ...

How did you "fine tune" your AOA? What do you mean when you say "keep increasing AOA"? I've tried adjusting the configuration and speed at which I declared a "stall" in the AOA cal procedure but have yet to find a combination that I like.

Basically just what you said. Instead of pulling it all the way to a deep stall, I used a higher speed and just firmly dropped the nose at a speed slightly before the stall and then re-try. it took quite a few tries to get it where I wanted it.