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  #1  
Old 05-15-2023, 08:22 AM
MJS MJS is offline
 
Join Date: Aug 2015
Location: New Hampshire
Posts: 5
Default RV9 OAT

I would like to put the OAT on the underside of the fuselage just behind the bulkhead at the rear of the baggage area. This would put it about 7' behind the firewall.

Is this going to be okay ?

Mark S.
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  #2  
Old 05-15-2023, 08:28 AM
BH1166 BH1166 is offline
 
Join Date: Nov 2017
Location: Eatonton Georgia
Posts: 866
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Nothing in potential heat flow is going to be accurate. Lot put out on underside of wing. Mine is pretty accurate +/-3 and mine is in pilot side fresh air naca duct. The error is heat from cowl, being it is so close. Just one opinion, others coming.
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RV6A Purchased N72TX
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  #3  
Old 05-15-2023, 09:09 AM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 11,763
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Quote:
Originally Posted by MJS View Post
I would like to put the OAT on the underside of the fuselage just behind the bulkhead at the rear of the baggage area. This would put it about 7' behind the firewall.
Is this going to be okay ?
Mark S.
You will still get noticeable heat at this point. If you are going to put it on the fuselage, the farther back the better. Many people opt for under the right hand horizontal stabilizer. This is where I put mine and it is pretty accurate.
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  #4  
Old 05-15-2023, 11:25 AM
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RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 901
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Here is what Davtron says on OAT location:
"NOTES: THE TEMPERATURE SENSOR MOUNTING SHOULD BE IN A PLACE THAT IS FREE OF EXHAUST GASES OR COWL FLAPS AIRFLOW. THE IDEAL PLACE IS TWO FEET OUT FROM THE WING ROOT ON THE BOTTOM OF THE WING. SENSOR LEADS MAY BE LENGTHENED OR SHORTENED WITHOUT AFFECTING
CALIBRATION."

Here is what the Dynon SkyView manual says on OAT location:
"Sensor Location

The SV-OAT-340 is an outside air temperature sensor. In order for it work properly, it must be able to measure air temperature accurately. Avoid exposing the sensor to sources of heat that would interfere with outside air temperature readings such as:
  • Direct sunlight
  • Engine heat and exhaust
  • Aircraft interior (back side of sensor)
  • Heated air from the cabin exiting from an open window or cabin air exhaust port
  • The installation area should have space for a nut and wires on the back side of the sensor. It is acceptable to extend or reduce the wire length if necessary. Reduce the wire length by cutting out the desired length from the middle of the wires and splicing together the remaining ends.
  • If there is a backup ADAHRS in the SkyView system, it is acceptable to install a backup OAT sensor a few inches away from the primary sensor. Consider running primary and backup OAT sensor wiring together. Tape sensor wire pairs together to avoid confusion later."

FWIW, my RV-8 (IO-360-M1B) has a Dynon OAT probe on the aft fuselage under the right stab. A friend retrofitted a Davtron OAT probe (for an AV 30) for his RV-8 on the second outboard inspection panel of the left wing. We have compared OAT readings on several occasions when flying close together and they differ by 1F at the most. I have heard anecdotally that the 'aft fuselage under the right stab' location does not work as well for RV's with larger engines (like those for the RV-10).

My RV-8:



My friend's RV-8:

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  #5  
Old 05-15-2023, 12:24 PM
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MacCool MacCool is offline
 
Join Date: Aug 2020
Location: central Minnesota
Posts: 1,670
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Anywhere in the line of the exhaust would seem to be a bad place for a temp sensor. I put my Dynon OAT on the outboard-most inspection panel on the underside of the left wing. The wiring was twisted and ran in the same conduit as the AoA and pitot tubing. Works fine in that location
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  #6  
Old 05-15-2023, 01:54 PM
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Dugaru Dugaru is offline
 
Join Date: Jan 2016
Location: Richmond VA, USA
Posts: 707
Default NACA duct

Mine was originally in the pilot-side NACA duct and proved to be very inaccurate there. Reads perfectly now that it's out in the wing. Unfortunately now my true airspeed has gotten slower.

Quote:
Originally Posted by BH1166 View Post
Nothing in potential heat flow is going to be accurate. Lot put out on underside of wing. Mine is pretty accurate +/-3 and mine is in pilot side fresh air naca duct. The error is heat from cowl, being it is so close. Just one opinion, others coming.
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  #7  
Old 05-16-2023, 05:40 AM
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Sportquattro Sportquattro is offline
 
Join Date: Nov 2020
Location: Ivybridge UK
Posts: 82
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I put mine in the inboard inspection panel on the Starboard wing. Works well and easy to access if needed.
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Nigel Heald
RV9a G-CSAM @ Exeter EGTE UK
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  #8  
Old 05-16-2023, 05:46 AM
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DarylT DarylT is offline
 
Join Date: Mar 2005
Location: Houston, TX
Posts: 466
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I had to move mine from the NACA duct. Opted for the Left wing inboard inspection bay cover. Works much better.
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  #9  
Old 05-16-2023, 08:51 PM
eric.the.blonde eric.the.blonde is offline
 
Join Date: Mar 2017
Location: Ann Arbor
Posts: 58
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I opted to put the sensors under the h-stab rather than the wing. The discerning factor was the location of the ADAHRS units which are mounted near the bulkhead behind the baggage bulkhead.
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