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Garmin GAP 26 location question

GarthR

I'm New Here
Hello Everyone,

I am currently working on my RV14 QB wing build and I am planning the install of a Garmin G3x AOA GAP 26 heated and regulated Pitot Probe/AOA. On page 5-2 and page 5-3 (pdf document pages 66 & 67) of the Garmin G3x manual

https://static.garmin.com/pumac/190-01115-01_am.pdf

it states that for ‘Optimal’ AOA functionality, the tip of the probe should be no further back than 25% of the wing chord. A diagram is shown on page 5-3. I figure the aft suggested limit at 14” aft of the leading edge on the RV14. This is not achievable mounting the unit aft of the spar. Closest I think I can get is 16” aft which in percent is 28% aft. I’m using Dynon pitot tube mount #102813-000.

My question is to anyone flying the RV14 with the Garmin GAP 26: 1) Where have you mounted it, and 2) if you have mounted it aft of the main spar, have you had any issues with the AOA?

Thanks in advance!

-Garth Richards
 
Thanks for the quick reply. I've read some of those threads, talked to Garmin and talked to Vans on the phone. Garmin says their graph is for optimal performance of the AOA but its not a requirement to be within the forward 25% of the chord line. They suggested I ask Vans. Vans said they hadn't had any reports of problems but to check VAF. After searching the threads here, it doesn't seem like anyone has any AOA accuracy issues with the aft of spar mounting even though that puts you at 28 to 30% of chord line. With that I feel comfortable doing the same. Attached (hopefully!) is the graph from page 5-3 so you see what I was referencing.

Apologies if it doesn't upload!

Thanks,

-Garth
 

Attachments

  • Pitot mounting.pdf
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I think you would find mounting in the leading edge hard to engineer and service. Putting it just aft of the spar is easy and works great. Which bay to use is up to you but I put it about where the plans have the vans pitot.
 
I am not sure on the difference between the Dynon pitot and Garmin Garmin looks maybe a hare shorter. I did a rough measurement and get about a 57 inch cord line. 25% of that is 14.25 inches. My Dynon mast and Pitot mounted as depicted in the manual just behind the spar results in the tip of the pitot right at 14.25 inches aft of the leading edge. If the Garmin pitot is a hare short you would be just a hare aft of "Optimum"

The Dynon Pitot is 7.75 Inch long front to back with the tip to front of the mast distance 5.75 inches.
 
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