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OAT Probe Location Recommendation?

D

Dean Pichon

Well Known Member
Hi,

I'm looking for recomendations for locating an OAT probe in my (flying) -4. I recently installed a D10A and would like to incorporate OAT capability. I'd like to find an accurate, minimally invasive, unobtrusive, and easy-to-wire location for the probe. (How hard can that be?) Thanks in advance for the help.

Dean
 
Put it out in the wing somewhere. The air around the fuselage is always hotter than ambient, unless you're flying a Long-Eze. There was an 11 degree difference on my RV-4 and on my Rocket. This was measured in the fuselage NACA vents and wing roots, -vs- out in the wing near the bellcrank access access holes.

This is also a good reason to add underwing fresh air vents during construction.

Dean, if putting it out in the wing seems like too much trouble, just remember that bad data is worse than no data. Hopefully, your RV-4 has a wing conduit installed already!

YMMV.
 
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I placed my Dynon OAT on the right side of the fuselage in the shade under the right elevator.
Seems to work well for me--on an RV-7A.
 
Rodney said:
I placed my Dynon OAT on the right side of the fuselage in the shade under the right elevator.
Seems to work well for me--on an RV-7A.
Click to expand...

I put mine here as well, but have not been in the air yet. My OAT is wired to the Dynon Magnetometer harness, so was placed here in part for convenience. Read many posts with folks using this location successfully.

Larry
 
I have mine on the inspection panel just under the LE of the left HS. I did it on the inspection panel so that I could move it if it's seeing too much air from the cowl. So far, seems to be pretty accurate.
 
quick and easy

On both my RV's I placed the probe behind the flap and tie wrapped it to the the lightening holes on the flap brace W421. Out of the sun and away from the fuselage and out of sight.

Steve
 
rightrudder said:
I like that solution. :)
Click to expand...
The problem with that location is that it really isn't OUTSIDE. Once enclosed by the intersection fairing it will be INSIDE the tail cone. Perhaps it might be close to the actual outside air temperature but it will most likely receive some heat from being enclosed INSIDE the airplane. Putting it out near one of the wing access plates will get the probe OUTSIDE in the OUTSIDE AIR, it will be easily accessible from the access plate and it can be relatively easy to run wiring from that location into the fuselage and to the instrument.

These pics are not very good of my installation but you can see at the yellow circle where the OAT probe is installed just inboard of the first access plate in the left wing:
Front%2520view%2520of%2520446RV.jpg


left%2520wing%2520446RV.jpg
 
RVbySDI said:
These pics are not very good of my installation but you can see at the yellow circle where the OAT probe is installed just inboard of the first access plate in the left wing
Click to expand...

Same location here - works great. Moved from NACA vent, which was not very good at all.
 
RVbySDI said:
The problem with that location is that it really isn't OUTSIDE. Once enclosed by the intersection fairing it will be INSIDE the tail cone. Perhaps it might be close to the actual outside air temperature but it will most likely receive some heat from being enclosed INSIDE the airplane.
Click to expand...

Yeah, I understand that?it partly depends on how "drafty" your empennage fairing is.
 
I know you want experience here, but I researched this and will be mounting my OAT in the wing root, L/S. After phase I, I might just mount some thermocouples and see how different positions compare, but that is later.

Good luck with your location.
 
rightrudder said:
RVbySDI said:
The problem with that location is that it really isn't OUTSIDE...
Click to expand...
Yeah, I understand that…it partly depends on how "drafty" your empennage fairing is.
Click to expand...
It is plenty drafty in that location and you don't have to worry about knocking if off when washing the plane.

When I first taxi out, it will read high, no surprise there, but by the time I'm climbing out, it matches the other planes I have flown with, within a degree or two, even on very cold days when I have the cabin heat on.

Also, my empennage fairing is very tight. There is just that much air going through our cockpits that it doesn't really matter.

Probably the worst place for the OAT probe is in the NACA vent.
 
we put our outside air temp on the inspection plate in the tail of the plane. It's out of the sun and far enough away from the engine to be accurate
 
Does anyone have any guidance as to accuracy of an OAT probe mounted inside the wing near the aileron bell crank vs mounted on the bottom of the wing in the slipstream?

Thanks,

Jeff
 
N941WR said:
It is plenty drafty in that location and you don't have to worry about knocking if off when washing the plane.

When I first taxi out, it will read high, no surprise there, but by the time I'm climbing out, it matches the other planes I have flown with, within a degree or two, even on very cold days when I have the cabin heat on.

Also, my empennage fairing is very tight. There is just that much air going through our cockpits that it doesn't really matter.
Click to expand...

Yes, a nice protected spot, straightforward wiring and no extra drag for the knots-obsessed. Me gusto mucho.
 
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