Alpha AOA Install

[ilovecornfields]

Anyone have any positive experiences getting an Alpha AOA installed in an Ovation? A couple of mechanics I spoke with were less than excited about the prospect of doing the installation.

[carusoam]

What would make the O different than another M20 for that device?

There are a few Alphas around here...

Best regards,

-a-

[DonMuncy]

I really like my Alpha AOA. 

[JohnB]

3 hours ago, ilovecornfields said:

Anyone have any positive experiences getting an Alpha AOA installed in an Ovation? A couple of mechanics I spoke with were less than excited about the prospect of doing the installation.

I had an Alpha systems AOA installed in my Bravo a few years ago. Hugely positive experience. My installer had not installed one before. I suspect your mechanics may be voicing to you uncertainty If your installer also has never installed one. It's a very simple install and the installation manual that comes with it was really easy to follow according to my installer, took less than a day, as it attached to a wing inspection plate. Doesn't require an STC, as it is classified as a minor modification. My installer had to adjust mine once after a test flight, then after I calibrated it in flight, haven't had to touch it in years. Very accurate, very helpful in detecting and alerting you about pre-stall conditions well before your stall horn does anything. 

[Txbyker]

7 hours ago, ilovecornfields said:

Anyone have any positive experiences getting an Alpha AOA installed in an Ovation? A couple of mechanics I spoke with were less than excited about the prospect of doing the installation.

I did a pirep in Avionics.  I wouldn’t waste your time with their full flap module if you have a GX.  It works well.  I have the HUD.

Russ

[ilovecornfields]

Thanks for the comments. I guess I should have done a better job explaining what I needed. I have the Alpha AOA with HUD sitting in a box, I’m just looking for recommendations on who has experience doing the installation since my mechanic didn’t seem excited to do it. 

[KSMooniac]

I installed mine under supervision...it isn't difficult, just tedious to route the tubes and wires. It needs a circuit breaker, and place for the control module, and an audio connection thru the audio panel. Any A&P or avionics shop should be able to handle it.

Sent from my LG-US996 using Tapatalk

[Robert C.]

Can't help with a recommended installer as I'm on the other coast

One bit of advice: be sure to tell your guy/gal to set the probe angle to 40 degrees ( If you don't he'll have to do it after your first flight when you discover the original angle didn't work).

Less tongue in cheek: I found the Alpha Systems extremely helpful. They'll happily talk to you and your AP so when in doubt give them a call. Will likely save you time and hassle.

[Gary0747]

I have the BK made by Alpha. I really like mine i did not get the heated probe and have never had a problem. You can add this later. I just wonder if anyone has ever had a problem with water or ice?

[Cruiser]

The install is easy to do but will take some time. It would be best to do it during an annual. We put it in the right wing. See attached image. Using the inspection plate for the mount, the cable and tubes had to loop further outboard and come back along the internal leading edge of the wing. The module was mounted in the belly under the passenger seat. The indicator is on the glare shield just to the left of center. I can see it while looking out the windshield during approach.

I have this  unit feeding pitot pressure to my iLevil AW2 ADS-B reciever. It has an app for AHRS display of the standard six pack gauges. Using the pitot tube from the AoA I get the actual altitude, airspeed and vertical speed for the six pack display.

[Piloto]

How good this AOA is in icing conditions, since on icing is where you need it most, specially when landing with ice on the wings.

José

[kortopates]

44 minutes ago, Piloto said:

How good this AOA is in icing conditions, since on icing is where you need it most, specially when landing with ice on the wings.

José

Alpha Systems provided a heated pitot tube option for that reason.

Edited January 18, 2018 by kortopates

[KSMooniac]

Alpha Systems provided a heated pitot tube option for that reason.

I'll argue quite the opposite... If you're carrying ice, your airfoil is now different, which means your stall speed/angle of attack is also different. The fact that your pristinely calibrated AOA system is ice-free means it will give you data that no longer applies if you're iced up. If you find yourself in this state, it is best to pull the AOA breaker, find a long runway, and carry some extra speed.

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[kortopates]

On 1/18/2018 at 12:29 PM, KSMooniac said:

I'll argue quite the opposite... If you're carrying ice, your airfoil is now different, which means your stall speed/angle of attack is also different. The fact that your pristinely calibrated AOA system is ice-free means it will give you data that no longer applies if you're iced up. If you find yourself in this state, it is best to pull the AOA breaker, find a long runway, and carry some extra speed.

Sent from my LG-US996 using Tapatalk
 

Absolutely a contaminated wing will stall earlier and extra speed or more precisely a lower angle of attack should be carried through the approach and landing. But who is to say an AOA indicator no longer applies or is useless? True that one won't be using it to target for the normal Vs x 1.3 approach speed  but its value doesn't end there.

Air speed alone tells you nothing about your margin of lift in any phase of flight, while an AOA is still indicating your actual AOA, we just need to recognize that the max critical angle of Attack (CLmax) is now considerably less.

NASA icing studies have equipped us with some very good information that we can utilize. Their studies have shown that on our GA airframes, that Rime icing typically can reduce stall angle from 18 to 11 degrees in 20 min. And that Clear icing was significantly more detrimental to performance reducing stall angle from 18 to 8; both in 20 min. Perhaps more useful for us is that they also indicate that just a bit of icing can typically reduce CLMax by 30% and large accretions in the form of clear ice horns on the leading edge typically reduce CLMax by 50-60%. Therefore they recommend maintaining a clean configuration at an airspeed of Vs x 1.5 or 1.6. I'll maintain that the "useless" AOA can be used as a reminder to keep the wing unloaded on the approach as we get near the landing environment since after all most icing accidents occur in the final approach/landing phases of flight. Therefore keeping the AOA in the solid green zone is going to help.

But absolutely, a lower angle of attack on the approach and landing is critical, but I'll maintain a CDFA (continuous descent final approach) to keep the wings unloaded, keeping the airframe in a clean configuration (except for the gear) without flaps,  manually flying without AP (so you'll feel any buffet) and selecting a long enough runway to allow for the extra airspeed are all important considerations to a successful approach with an iced airframe. 

Some worthwhile references: AC_91-74B, NASA's Online Aircraft Icing Training Course

 

Edited January 21, 2018 by kortopates

[JohnB]

One other plus the AOA is great for is determining best speeds irregardless of your weight, that helps to make perfect landings every time and even more important, but hopefully never to be needed,  your best glide speed if you ever need it. You just fly your aoa best glide and you will get your best glide speed without having to factor in your gross weight.