OAT prob location

Bavafa · #1 02-15-2018, 08:41 AM

Just wondering if there are any pix of the installation of the probe and report of their accuracy. In my RV7 I had two probes, one in NACA air vent and one in the wing root area that read the same at all times but have heard of many opinions that in the airstream or near the cowl is not a good place to install them. Thoughts and pictures would be appreciated. BTW, I am planning on G3X system.

Jpm757 · #2 02-15-2018, 10:02 AM

I placed my Dynon OAT probes for my dual ADAHARS units on the left and right inboard lower wing inspection covers. Identical readings, no issues. Just run a plug to the wing root and attach with wing installation.

Bavafa · #3 02-15-2018, 11:01 AM

Jake,
Do you have it in the air stream or inside of the wing out side of the air stream?

n982sx · #4 02-15-2018, 12:25 PM

I have a G3x Touch system and I just installed it in the pre-punched hole in the underside of the left wing. That's what the hole is for. I can't think of any good reason to put it anywhere else.

It works great and I find it very accurate.

Jpm757 · #5 02-15-2018, 06:49 PM

My probes are in the slipstream, and at RV speeds the ram rise is negligible. Inside the wing would tend to heat soak the probes on the ground during hot weather providing innacurate data to your ADAHARS units during taxi, takeoff and initial climb.

Toobuilder · #6 02-15-2018, 06:55 PM

I have mine directly behind the pitot mast. In free air, but the mast destroys the ram rise. Works great. Had it in the tail various places and it always read high in flight. There is a lot of heat spilling out of the cowl of the Rocket and it just got to the probe somehow.

N941WR · #7 02-15-2018, 09:20 PM

I put both of mine under the empennage fairing. Once air starts moving, they will read within one or two degrees of the people I have flown formation with.

(Click to enlarge)

When I added a second OAT probe, it went in the open tooling hole, above the OAT probe in this picture.

Weasel · #8 02-16-2018, 05:21 AM

Quote:

Originally Posted by N941WR

I put both of mine under the empennage fairing. Once air starts moving, they will read within one or two degrees of the people I have flown formation with.

(Click to enlarge)

When I added a second OAT probe, it went in the open tooling hole, above the OAT probe in this picture.

I did the same. In the clouds as the temp slowly drops, ice starts collecting when the efis hits 33 or 32 deg. F. I say close enough to accurate for me. I also have very accurate TAS readings from the EFIS at any temp indicating it is accurate at other temperatures.

N941WR · #9 02-16-2018, 08:46 AM

BTW, the reason I put it in that location, besides trying to save a 1/4 of a knot was that I don't have to worry about damaging it when washing the plane.

BillL · #10 02-26-2018, 05:29 PM

I put mine (G3X OAT probe)in the side of the fuse, aft of the wing spar, inside the wing root cavity. I tested it today against a k-type thermocouple. It started from a soaked hangar reading 3F low and stayed that way through taxi, climb, cruise and descent. Flight legs allowed sunny side and shady side, no difference.

The K-type was located on the opposite side of the plane, 36" out from the fuse and 6" aft of the wing spar. An open bead style 1" from the skin.

Using a 3-leg ASI calibration routine (twice), the TAS was within .12 kts of the GPS. The OAT reading is possibly off setting some other variance. Never the less - the data indicates that" 1. the RTD is lower than actual, and 2. the location provides adequate tracking of OAT for flight.