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OAT senson placement on RV4

gggflyer

Active Member
The OAT sensor on my newly acquired rv4 is hidden in the space between the flap and fuselage and not in direct contact with outside air. Would this still provide adequate readings in flight. I come from the certified world where all OAT sensors are usually out in the open.

Has anyone not placed their OAT sensor on the outside and seen any errant readings?

Thanks

G
 
I've seen them stashed about anyplace you can think of. In the fresh air vent, under the Emp Fairing, inside the wingroot, etc. I'm still of the thought that it needs to be exposed to fresh air away from ANY cooling air leakage.

I always put mine on the bottom of the wing next to an inspection plate. I've seen them on the inspection plate as well, but that didn't make sense to me as you are stressing the wires every conditional.
 
The OAT sensor on my newly acquired rv4 is hidden in the space between the flap and fuselage and not in direct contact with outside air. Would this still provide adequate readings in flight. I come from the certified world where all OAT sensors are usually out in the open.

Has anyone not placed their OAT sensor on the outside and seen any errant readings?

Thanks

G
I have two sensors installed over the 20 years of flying my 4.
The first, in the wing-root area, outside of the air-flow.

Not very accurate.

Sensor #2 is mounted bottom side of the outboard wing, near the tip. More or less mid-chord.
Very accurate. It’s out of direct sunlight and in the airflow.
 
ive got mine mounted under the horizontal on the side of the fuse just forward of the inspection plate for the elevator horn. its dead accurate there.

bob burns
RV-4 N82RB
 
My plane originally had the bent tube style pitot. When I removed it and installed a normal AN style pitot mast, I found my OAT sensor dropped right in that hole. It’s given me no issues with accuracy and almost exactly fits what most manufacturers recommend for generic placement - underside of the wing about 2-3’ out from the root.
 
Placed my Dynon OAT just in front of the (Van's) pitot tube, thinking it might reduce drag a bit -- combining drag from OAT and pitot tube fitting).

Recently moved my engine monitor OAT from half-way down the left gear leg to the forward rim of the engine air intake. In my installation that's about 3/4" behind the prop edge. That increased it's temp to 10 to 18F over the Dynon OAT reading. Still haven't figured out why, but something must be going on with the air near spinner, prop and air inlet.

It would appear you really want your OAT probe in the shade from the sun, out of prop blast and free of air heated by cowling.

Finn
 
It would appear you really want your OAT probe in the shade from the sun, out of prop blast and free of air heated by cowling.

Finn

Yep. I had mine in the wing root then one day noticed when I leaned and EGT went from 900F to 1300F, the OAT followed it. I installed some thermocouples in various places and concluded the same, exactly the same as you describe. It got moved to an inspection plate under left wing.
 
I have two. One is in the inlet to the forward cabin air vent and the other is in the bottom of the rt wing just next to the bellcrank inspection plate. They both read exactly the same.
 
Placement

I suspect there are a lot of variables at play here. I had two, one in each forward cabin airvent inlet, and the reading was quite inaccurate - okay on the ground, but as much as 20 degrees off in the air (estimating).

Vic Syracuse warned me that moving the probes to a better location would make my airplane "slower," and he was right! :)

I have two. One is in the inlet to the forward cabin air vent and the other is in the bottom of the rt wing just next to the bellcrank inspection plate. They both read exactly the same.
 
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