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doctornigel

Active Member
I got my wing kit yesterday and I'm looking at AOA systems, anyone chime in?
The AFS system looks nice but I'm also looking at the Dynon system. As far as I can tell the AFS uses a extra hole in the wing and the Dynon uses a specific pitot tube. Added benefit with the Dynon is I can use it as the backup AI. What don't I know and what other systems had anyone used/installed. Thanks
 
AOA

When I built this airplane I was convinced I needed an AOA...Then I had to wait for Dynon to fix the problems with their heated pitot and sort of forgot about it.

I must say even though AOA is a wonderful invention, until you mentioned it I'd forgotten all about an AOA...Besides doing aerobatics I think the thing would be sqwarking at me waay too much.

Purely personally but the the 7 at least is a very docile aeroplane..I just can't imaging going to the trouble of hooking it up now.

Frank
 
I decided to go with the Dynon. You still have a little while before you have to finalize your decision, though.
 
AlphaSystems AOA

Also check Alphasystems. Simple system, uses own pitot, provides superb customer service. I called to buy a replacement part--he wouldn't let me pay and instead updated my entire system, no charge.

http://alphasystemsaoa.com/
 
frankh said:
.Besides doing aerobatics I think the thing would be sqwarking at me waay too much.

Purely personally but the the 7 at least is a very docile aeroplane..I just can't imaging going to the trouble of hooking it up now.

Frank
Click to expand...

Hi Frank.

I would disagree here. I don't do aerobatics to the same degree you do, mainly just variations of loops and rolls. I almost never hear the AOA squawking. Occasionally it will talk to me if I'm pulling too hard at the top of a loop, but I'm convinced it has saved me from some unintentional snap roll at odd attitudes.

I have and like the AFS (nee PSS) sport AOA. It works very well.

One thing I did that was unusual was to add a second blade-type pitot tube which gives the AOA its own independent pitot/static source. It had no connection at all to the other instruments in the airplane.
 
Get the AOA

Coming from someone who has flown behind an AOA for a while (F-14, T-45). I don't mind hearing from the system when doing aerobatics. It's the peace of mind in the pattern, knowing that I'm not close to stalling the wing that made the decision for me. I chose Dynon. However, I would recommend some sort of AOA system even if it isn't the Dynon system, as long as it is accurate in the landing configuration. They let us Navy guys trust that AOA system to bring aircraft aboard boats, so they must be idiot proof:D
 
I have the AFS AOA and love it. It actually uses a pair of very small holes (#60) in the most outboard bay of the wing - not even noticable.

Bob
RV-10 N442PM (flying)
 
I am not sure how much difference it makes...

AOA measures difference in air pressure. The AFS system is measuring the difference at the wing which is what is important to a pilot (lift).
The Dynon system is measuring at the pitot tube and it seems that it could be less accurate, due to installation error.

This is just speculation and I have never seen any data to back it up.

Kent
 
Dynon Difference

kentb said:
AOA measures difference in air pressure. The AFS system is measuring the difference at the wing which is what is important to a pilot (lift).
The Dynon system is measuring at the pitot tube and it seems that it could be less accurate, due to installation error.

This is just speculation and I have never seen any data to back it up.

Kent
Click to expand...

A Dynon tech might be able to answer this better but.... You are correct that the Dynon measures from the pitot but from what I have read (not flown yet) you do a series of stalls to calibrate the system, this teaches the computer what the pressure difference is at the pitot during stall so though it is not measuring at the wing, it knows what it needs to know to predict the stall AOA. Seems like a nice set up, I do know some don't like to look at the EFIS for the AOA display which is why a remote display would be a nice add on to the Dynon. Some enterprising builders have done just that. I plan to wait and see how I like flying with the normal display.

Cheers
 
AoA

I'm going to install a Dynon AOA Pitot and hook it up to my AFS Sport AOA - I don't really want to drill a hole in my wing (and a drainage hole too!), so I figured this was a good compromise.

The only thing I'm worried about in both systems (pitot or on wing) is that they are only on one side, so you aren't getting any AOA reading for the other wing (which could be in a stall).

Maybe not a concern in practice, but how does that help you avoid the stall-spin accidents that happen on base to final?
 
I have read that in certain turning situations, that you can stall one wing before the other. In fact, most modern GA wings will stall progressively from the root outward (see Tim's "thread" on this). So the AOA probe is a warning device of stall of that portion of the wing where the probe is. I suspect that if the other wing stalls, then the AOA wing would show darn close to a stall as well. Maybe the calibration stalls could be done so the opposite wing stalls first and then the AOA would give you more warning. Problem there is, stalling one wing will probably put you into a spin.
 
Research first?

ccrawford said:
I'm going to install a Dynon AOA Pitot and hook it up to my AFS Sport AOA - I don't really want to drill a hole in my wing (and a drainage hole too!), so I figured this was a good compromise.
Click to expand...

I believe that if you research other posts on VAF you'll find that algorithms/methodology that AFS and Dynon use to calculate AOA are different, based on the different air pressure measurement devices, and so this will not work. You may want to check further before trying to mate the two.
 
AOA is my pet subject. I have installed the Dynon heated pitot on the port wing with plans for a Dynon system somewhere in the airplane. The Dynon has aural warnings so it eliminates the need for the stall warning vane. I also installed an InAir LRI - Lift Reserve Indicator - in the starboard wing (http://www.liftreserve.com/). The advantage of the LRI is that it's purely mechanical and uses an analog gauge. Because of this, you can mark such things as best glide, L over D max, etc. You can make your own, if you want; try this link: http://www.ch601.org/resources/aoa/aoa.htm
The AFS system is a good one as well. Van's plans actually show where to put it near the wing tip. Looks easy to do even after you're done building. I've also seen a movable vane on the wing tip of a flying RV-10 but know little about it.
John
 
"I'm going to install a Dynon AOA Pitot and hook it up to my AFS Sport AOA - I don't really want to drill a hole in my wing (and a drainage hole too!), so I figured this was a good compromise."

I can guarantee you that this will not work with our algorithms. We did extensive testing before Patenting the wing ports.

I have the AFS AOA-PRO, AFS EFIS-AOA, and Dynon AOA in my RV-4. I am very confident on what works.

Rob Hickman
Advanced Flight Systems
 
N401RH said:
I can guarantee you that this will not work with our algorithms. We did extensive testing before Patenting the wing ports.

I have the AFS AOA-PRO, AFS EFIS-AOA, and Dynon AOA in my RV-4. I am very confident on what works.

Rob Hickman
Advanced Flight Systems
Click to expand...

Well that answers that. Thanks!

I was hoping that I could simply calibrate the AOA using the pitot, knowing that the ranges may be different than what the normal wing port design would send to the system but I guess that's not the case. Now I'll have to drill holes in my wing -sigh-. :)
 
ccrawford said:
Now I'll have to drill holes in my wing -sigh-. :)
Click to expand...

Not that bad. The holes are so small, you have a hard time finding them.

I think that is the real reason for the decal:D

I have been flying with a buddy who has an AFS AOA, he is totally thrilled with it.

Installation is pretty simple, as long as you have the lines (or a conduit) already in the wing.
 
Re: AOA Systems

I have the Dynon AOA system and am very pleased with the performance. I have the audible alarm wired to my audio panel and I don't look to get the AOA picture, I listen, works just like a stall warning horn. Very good device in the pattern when head is on the swivel clearing for traffic. Besides, it came as part of the price of Dynon, why not use it? I had to buy a pitot tube anyway from someone. Additionally, I am one of those guys that if the equipment is from one manufacturer, Dynon and Garmin, I won't get the crossed finger pointing that it is the incompatibility issue of the other guy's black box. I have a -9A with O-360 FP Van's prop. Dan
 
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