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Old 02-09-2019, 07:41 AM
BlakeB BlakeB is offline
Join Date: Jul 2007
Location: Lafayette, La
Posts: 122
Question AOA Recomemdatins? GRT HX


Considering adding AOA indicator to my RV6. I have dual GRT HX screens. Would like to hear suggestions. I understand there is a HX (AOA) function that is probably available to me now....but donít know how to get it active... also understand itís not a true AOA function.... I think.

Would like to hear everyoneís thoughts. Also, Iím in South Louisiana (Travel to Houston often). Any recommendations on installers. (To update my system with AOA functionality or install Alpha type AOA?


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Old 02-09-2019, 09:11 AM
h&jeuropa h&jeuropa is offline
Join Date: Jun 2008
Location: Kalamazoo, MI
Posts: 221


Have a look at the Horizon HX HS WS User Manual Rev D on the GRT website. Page 2-7 tells about AOA and page 9-7 explains how to set it up. The calculated AOA works pretty well and the price is right to at least try it.

Jim Butcher
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Old 02-09-2019, 09:17 AM
lr172 lr172 is offline
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 4,006

I have AOA on my HXr setup and it works well. You will need a Pitot tube with AOA port on it (dynon or Garmin), as well as a new AHRS that has the AOA port in it.

I have an AFS AOA kit that I was planning to list for sale. It is new and came with my 10 kit and I didn't install it. PM me if interested.

RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress
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Old 02-09-2019, 09:32 AM
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Isaac Isaac is offline
Join Date: Nov 2009
Location: Peoria, Az
Posts: 130
Default GRT AOS

For a Horizon Hx you'll need an Adaptive ADAHRS with an AOA input and a AOA/Pitot probe (pitot port straight out the front and an AOA port below it, generally offset by 45 degrees). I think the Garmin AOA probe is the one GRT tested and recommends but supposedly the Dynon Pitot/AOA probe will also work.

From the GRT website, the AOA option for the Adaptive ADAHRS is a 250$ option. (AHRS-OPT-AOA).

I have the Proprietary Software Systems, Inc. AOA (same product as the Advanced Flight Systems AOA PRO/SPORT) in my RV6 along with Dual GRT Hx displays and am happy with it.

I can't comment on how the GRT AOA performs, but I think as a retrofit, it would be much easier to implement the GRT AOA. Install the AOA/Pitot probe, plumb the AOA port thru the wing to the ADAHRS and enable AOA on the Hx display.
RV6 N947J
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Old 02-09-2019, 11:16 AM
BobTurner BobTurner is offline
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,747

Just to summarize:
Your HX should have an AOA already available. It will display chevrons on the screen (yellow to red) and, much more useful imho, put out an audio alert, slow beeps moving to a steady tone at stall. This function is all done with software, using data the Hx already has. I have an Hx and a Dynon D6. The D6 has an AOA using raw data, comparing the pitot pressure and the pressure from a pickup 45 deg below the pitot (as described above). In tests, with a slow approach to stall, the Hx and D6 warnings are in good agreement. I have not done any rapid approaches to a stall, where the Hx may have some lag while it does the calculations. Newer Hxís, with GRTís Ďadaptiveí air-data computer, now use the same raw data as the Dynon. Either the Dynon or Garmin pitot will furnish the data. Iíd start by activating the calculated AOA, see if it meets your needs.
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Old 02-10-2019, 06:26 AM
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maniago maniago is offline
Join Date: Aug 2014
Location: Bowie MD
Posts: 847

Just a thought to consider. Ive not implemented this, but I think its a worthy project...

Also FWIW, I asked Jeff at GRT about adding sw for the F4 tones, and he said if he gets more requests hed consider it - but at this point hed never heard of this. He did think that as it stands the HX outputs would provide the Gen1 Onspeed info it needs.
MustangII (FoldingWing) "Finishing up": IO360B1E,RSA,C2YR-BF/F7666-2,Superior sump,James; 2xHXr,MiniX,EIS,480,327,240,SL30,Navworx; SteamAlt,AS,VSI,wet compass
Don't be a hater; I'm a cousin with thin wings!
N251Y (res)

Last edited by maniago : 02-10-2019 at 06:29 AM.
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Old 02-10-2019, 08:55 PM
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Jeff Vaughan Jeff Vaughan is offline
Join Date: Jan 2005
Location: West Chester, Pa
Posts: 549
Default Thumbs up for AOA tones

I flew my 7A for 8 years with just a visible AOA. I loved it BUT THEN WHEN I built my RV 12 I installed the ONSPEED F 4 tones. I only look at the panel once as I slow to the ONSPEED tone confirming my airspeed is about right. From that point on my head is looking out at the runway and looking for possible traffic conflicts.

Just the other day a 172 student pilot over flew me by about 100 feet My traffic gizmo was yelling traffic as I was turning to make my single turn approach. I had just slowed to THE ONSPEED tone . I was frantically looking all around as the 172 pilot announced that he was turning base. I had just announced my intentions before him. He did not hear me. My head was searching for him while I was on my slowed turning approach to land. I was comferted by the fact that I did not need to look down at my airspeed while trying to avoid the 172. I quickly found him slightly above and in front of me while my head was spinning around. I told him where I was and that I had just announced my base turn prior to his announcement and I had already turned. He responded that he was breaking off his approach.

I continued my ONSPEED approach to an uneventful landing. I did sit in the hangar and think about what had just taken place while I sipped my adult beverage. I love my ONSPEED AOA
Jeff Vaughan
RV 7A N561EV Sold
West Chester Pa

2019 donation current
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Old 02-11-2019, 09:34 AM
JDeanda JDeanda is online now
Join Date: Apr 2013
Location: Ventura, CA
Posts: 30

Blake, I have Proprietary Systems AOA for sale if you decide to go that route. Removed from a parted out RV-9A Complete with the processor, all the plugs, switches, sensors, installation and operation manual. You'll need to add wire and might need a bit more tubing (I tried to get it all out but didn't quite make it. Might be enough if you're installing on a shorter wing RV than the -9) $150 and I'll ship free.

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Old 02-11-2019, 10:29 AM
Canadian_JOY Canadian_JOY is offline
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,011

Again, a summary...

The basic HX has "computed AOA" built into it - no sensing port is needed, no other hardware needed.

Upgrade your AHARS to the Adaptive AHARS and add the AOA sensor port if you want to upgrade to full "sensed" AOA. I went this route. Didn't add a new combination pitot/AOA sensor but rather installed a home-brew AOA sensor fabricated from 1/8" aluminum tube. This tube is mounted directly behind the pre-existing heated pitot tube, following the aft contour of the heated pitot tube, wrapping around its bottom, then bending down at 60 degrees.

This setup works a charm. Nice AOA tones available in your ear as well as AOA chevrons on the EFIS if you care to look down. I never look down since the audio tones seem to work pretty much perfectly.

Do a search here on RV12 pulled rivet AOA sensor to see how easy it can be to install an AOA sensor port. This really, really is NOT rocket science!
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Old 02-11-2019, 10:39 AM
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maniago maniago is offline
Join Date: Aug 2014
Location: Bowie MD
Posts: 847

Originally Posted by Canadian_JOY View Post
Do a search here on RV12 pulled rivet AOA sensor
No joy on this search. Got a link instead?
MustangII (FoldingWing) "Finishing up": IO360B1E,RSA,C2YR-BF/F7666-2,Superior sump,James; 2xHXr,MiniX,EIS,480,327,240,SL30,Navworx; SteamAlt,AS,VSI,wet compass
Don't be a hater; I'm a cousin with thin wings!
N251Y (res)
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