AOA reset?
- Thread starter dougnlina
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- Mar 23, 2005
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If you perform multiple stalls during the test, it will look for and use the AOA calibration that results in the most conservative stall warning.
I have modified the static system to better calibrate my TAS. Does a new series of AOA calibrations "over-write" the previous calilbration, or "Add to" the data. I am having difficulty getting the AOA system to actually give me warning of an impending stall. Oddly enough it works perfectly DURING calibration. I feel like I need to "reset" whatever is in my calibration table.
DP
DP
airguy
Well-Known Member
If you want the warning of the impending stall to come a few knots earlier than it otherwise would, just do some standards stalls and note carefully the airspeed at which the aircraft ACTUALLY stalls - then run the AOA calibration routine and instead of performing a full actual stall, push the nose over at stall speed plus a couple knots. The AOA calibration routine will see the AOA change at that point and assume it was the stall, and set the aural indicator to begin chirping a few knots earlier than it otherwise would.
Note to Dynon - it would be nice if we had an option to select the aural warning band to "X knots wide above full stall" or "Begin Y knots above full stall".
Note to Dynon - it would be nice if we had an option to select the aural warning band to "X knots wide above full stall" or "Begin Y knots above full stall".
mmarien
Murray M.
The AOA can be set to start pulsing tones at the green/yellow border, mid yellow or yellow/red border. So if you can set it to start before the stall.
So I need to do a better job here describing what is going on, as they say, “I aint getting no satisfaction”
I honestly feel like there is a bug, or something wrong with my system. Specifically, I feel like my calibrations are not “taking” and there is an old (factory?) AOA calibration “stuck” in my system.
I have tried to calibrate the AOA system on about twelve different flights now and it simply does not work correctly. This is a feature that I was excited to have as part of my Dynon suite and I would like to get it to work. Here is the behavior I am experiencing: I go fly, get to a decent altitude and open the AOA calibration in flight menu. I fly and oscillate the nose up and down a few times then do a stall(s) in some configuration – I have tried no flaps, half flaps and full flaps – after the aircraft stalls I push the stall button. During this calibration process, the stall indicator and aural tone works properly. I hit SAVE and leave the calibration window. When I next do a stall, I generally get no aural warning and only half visual indication on the AOA. It is as if the calibration process is “not saving.” The best I have been able to do is get a solid tone and a very quick AOA indication right as the airplane breaks into the stall. Again, THIS IS THE FRUSTRATING PART, the system works perfectly while in the calibration menu, I hit save and leave the menu, AOA does not work. I have been lowering the numbers where the tones start and am now at 35% and 50% and while I can get tone, it is un reliable in relation to the actual stall.
WHEN LOOKING AT THE SAVVY data for the calibration the AOA percentage goes to 95%-100% during the calibration stalls. However, when you look at subsequent stalls (same flight but not in calibration mode) the AOA percentage only goes to 75% at the best. My tests do not seem to be “saving”.
This goes back to my original post where I was wondering how the data is logged and used by the Dynon system; does each calibration stall series over-write the previous data? or, does each calibration dataset “add to” previous data.
While I am now trying to “fool” the system by faking stalls as airguy suggested, this seems like a pretty half-baked way to go about setting up a system designed to save your bacon. BTW I have set up the same system on another aircraft and it works fine, this really does seem to be specific to my current aircraft/dynon configuration. Dynon?
Happy Holidays all
DP
I honestly feel like there is a bug, or something wrong with my system. Specifically, I feel like my calibrations are not “taking” and there is an old (factory?) AOA calibration “stuck” in my system.
I have tried to calibrate the AOA system on about twelve different flights now and it simply does not work correctly. This is a feature that I was excited to have as part of my Dynon suite and I would like to get it to work. Here is the behavior I am experiencing: I go fly, get to a decent altitude and open the AOA calibration in flight menu. I fly and oscillate the nose up and down a few times then do a stall(s) in some configuration – I have tried no flaps, half flaps and full flaps – after the aircraft stalls I push the stall button. During this calibration process, the stall indicator and aural tone works properly. I hit SAVE and leave the calibration window. When I next do a stall, I generally get no aural warning and only half visual indication on the AOA. It is as if the calibration process is “not saving.” The best I have been able to do is get a solid tone and a very quick AOA indication right as the airplane breaks into the stall. Again, THIS IS THE FRUSTRATING PART, the system works perfectly while in the calibration menu, I hit save and leave the menu, AOA does not work. I have been lowering the numbers where the tones start and am now at 35% and 50% and while I can get tone, it is un reliable in relation to the actual stall.
WHEN LOOKING AT THE SAVVY data for the calibration the AOA percentage goes to 95%-100% during the calibration stalls. However, when you look at subsequent stalls (same flight but not in calibration mode) the AOA percentage only goes to 75% at the best. My tests do not seem to be “saving”.
This goes back to my original post where I was wondering how the data is logged and used by the Dynon system; does each calibration stall series over-write the previous data? or, does each calibration dataset “add to” previous data.
While I am now trying to “fool” the system by faking stalls as airguy suggested, this seems like a pretty half-baked way to go about setting up a system designed to save your bacon. BTW I have set up the same system on another aircraft and it works fine, this really does seem to be specific to my current aircraft/dynon configuration. Dynon?
Happy Holidays all
DP
airguy
Well-Known Member
Well, I never claimed it was good way - only that it was one way to do it!
It's interesting that you say the AOA percentage does not approach 90's-100 during subsequent stalls, is that in exactly the same configuration as previously calibrated?
Sorry, pulling foot out of mouth, no slight intended airguy. I have tried to do calibrations with single and multiple flap configurations, then stalled it in single and multiple configurations, configuration changes do not seem to change anything but the speed at which the stall breaks. But i have tried various configurations and combinations. I seem to have two worlds, one while calibrating and one when out of the calibration menu that "sees" the AOA percentage about 25% lower than when in the mode. BTW the screen threw up a System 5 event today, now wondering if that has anything to do with it...
DP...I hope the foot extraction procedure was not too painful...Yikes...visual image was very clear...equally clear was your text on your challenge getting the AOA to work as you intend...good description.
>just do some standards stalls and note carefully the airspeed at which the aircraft ACTUALLY stalls - then run the AOA calibration routine and instead of performing a full actual stall, push the nose over at stall speed plus a couple knots. The AOA calibration routine will see the AOA change at that point and assume it was the stall, and set the aural indicator to begin chirping a few knots earlier than it otherwise would.
I think that I will need to do something similar because my airplane is a pusher canard and these designs do not really stall...they just "mush" when the fore-plane (canard) aerodynamically stalls it just kind of "twitches" but there is no noticeable change in pitch of the airplane nor any discernible change in AOA so I guess I will need to fake out the system and manually lower the nose at the speed where I want the "stall" to occur and then the Dynon AOA magic will think that is the actual stall and display/chirp accordingly.
>Note to Dynon - it would be nice if we had an option to select the aural warning band to "X knots wide above full stall" or "Begin Y knots above full stall".
Yes please...add me to the list.
>just do some standards stalls and note carefully the airspeed at which the aircraft ACTUALLY stalls - then run the AOA calibration routine and instead of performing a full actual stall, push the nose over at stall speed plus a couple knots. The AOA calibration routine will see the AOA change at that point and assume it was the stall, and set the aural indicator to begin chirping a few knots earlier than it otherwise would.
I think that I will need to do something similar because my airplane is a pusher canard and these designs do not really stall...they just "mush" when the fore-plane (canard) aerodynamically stalls it just kind of "twitches" but there is no noticeable change in pitch of the airplane nor any discernible change in AOA so I guess I will need to fake out the system and manually lower the nose at the speed where I want the "stall" to occur and then the Dynon AOA magic will think that is the actual stall and display/chirp accordingly.
>Note to Dynon - it would be nice if we had an option to select the aural warning band to "X knots wide above full stall" or "Begin Y knots above full stall".
Yes please...add me to the list.
airguy
Well-Known Member
I believe on the canard types the forward canard will actually stall first and drop the nose so the main wing does not stall, correct? So the highest angle of attack will always be seen by the canard - can you put the pitot/AOA on the canard section? Or is your only option on the main wing?
>I believe on the canard types the forward canard will actually stall first and drop the nose so the main wing does not stall, correct?
Yes...the canard airplanes are considered to be "stall proof". When the canard stalls it just drops very slightly and then starts flying again while the main wing never gets to stall angle of attach so there is really no appreciable change in pitch...in other words the canard stall is more like a nibble and the airplane just mushes down. At very heavy weights the canard stall will twitch as the airplane stalls but again there is really no appreciable pitch down.
>So the highest angle of attack will always be seen by the canard - can you put the pitot/AOA on the canard section? Or is your only option on the main wing?
Good thinking...Yes placing the AOA probe on the canard would be the preferred place however I am doing a retrofit so it was easier to put it on the main wing. It would really not make much of a difference because the canard just nibbles as it stalls .
I think the only way I can get the Dynon magic to do its thing is to fly close to the IAS of the nibble but just before it nibbles I should drop the nose to teach the Dynon AOA magic that this angle of attack is the "stall" AOA.
Yes...the canard airplanes are considered to be "stall proof". When the canard stalls it just drops very slightly and then starts flying again while the main wing never gets to stall angle of attach so there is really no appreciable change in pitch...in other words the canard stall is more like a nibble and the airplane just mushes down. At very heavy weights the canard stall will twitch as the airplane stalls but again there is really no appreciable pitch down.
>So the highest angle of attack will always be seen by the canard - can you put the pitot/AOA on the canard section? Or is your only option on the main wing?
Good thinking...Yes placing the AOA probe on the canard would be the preferred place however I am doing a retrofit so it was easier to put it on the main wing. It would really not make much of a difference because the canard just nibbles as it stalls .
I think the only way I can get the Dynon magic to do its thing is to fly close to the IAS of the nibble but just before it nibbles I should drop the nose to teach the Dynon AOA magic that this angle of attack is the "stall" AOA.
Raymo
I love aviation!
I will have to use Airguy's method (Thanks!) for my RV-7A. I've done the calibration twice with the last one using no flaps. Still, just before touching down/staling during landing I get the beep to start, which is essentially just providing stall warning. I'd like to hear it earlier to better manage the energy and angle of attack.
DP - it sounds like you're doing all of the right things. A few thoughts: I'm wondering if the time that you're pressing the stall button is affecting anything (IE, to temporally close to the stall, before full recovery). Don't press stall immediately after the break/recovery. Actually recover the airplane back to a lower AOA, then press stall. But barring that, there's a chance that the system event might be a factor here. Best bet would be to contact our support team to have that looked at (425-402-0433 or support at dynonavionics dot com). Another thing you can look at if you're more technical is a settings export. The AOA calibrations are pretty easy to find, and seeing if it changes across a couple of separate test calibration attempts would be interesting here. Finally, know that during the calibration you're seeing more of a "raw" version of the AOA to pitot ratio, vs an actual AOA calibration. But if that's behaving seemingly correctly (increases with actual AOA increase), then you should be able to get a valid calibration.