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OAT probe location

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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 04, 2014 1:13 pm Post subject: OAT probe location

All,



I offer half my kingdom to anyone who will give me a proven location for an OAT thermocouple which is part of my “aftermarket” EMS.



with appreciation,



Fred

davidjoyce(at)doctors.org
Guest

Posted: Sat Oct 04, 2014 1:41 pm Post subject: OAT probe location

Fred, It works nicely just in front of the starboardflap 

activator slot, hidden by wing root from sun, but in full 

contact with outside air between flap end & fuselage. 

Starboard to avoid exhaust fumes. Regards, David Joyce, 

GXSDJ

PS Before I accept, how big is the kingdom and how surly 

are the natives?



On Sat, 4 Oct 2014 14:13:12 -0700

  Fred Klein <fklein(at)orcasonline.com> wrote:

 	  Quote: 	
		   

<fklein(at)orcasonline.com>

 

 All,

 

 I offer half my kingdom to anyone who will give me a 

proven location for an OAT thermocouple which is part of 

my “aftermarket” EMS.

 

 with appreciation,

 

Fred

 

Un/Subscription,

Forums!

Admin.

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 04, 2014 2:18 pm Post subject: OAT probe location

On Oct 4, 2014, at 2:40 PM, David Joyce <davidjoyce(at)doctors.org.uk (davidjoyce(at)doctors.org.uk)> wrote:

 	  Quote: 	
		  Fred, It works nicely just in front of the starboardflap activator slot, hidden by wing root from sun, but in full contact with outside air between flap end & fuselage. Starboard to avoid exhaust fumes. 	




David…your suggestion much appreciated…however, you will note in attached photos that on my ship, the slot gets buried within my enhanced wing root fairings. I fear that the probe will reach interior cockpit / aft fuselage temps. Care to comment on whether my fears are justified?…

Any suggestion (anyone!) for an alternate location…?...

 	  Quote: 	
		  PS Before I accept, how big is the kingdom and how surly are the natives? 	




My kingdom is a very small part of a small rock in the Salish Sea just south of Vancouver, B. C., and the natives can be very surly, especially when they’re restless.

Fred

 	  Quote: 	
		  On Sat, 4 Oct 2014 14:13:12 -0700Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)> wrote: 	  Quote: 	
		  --> Europa-List message posted by: Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)>

All,

I offer half my kingdom to anyone who will give me a proven location for an OAT thermocouple which is part of my “aftermarket” EMS. 	
	




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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 04, 2014 2:51 pm Post subject: OAT probe location

Has anyone place an OAT probe at the front of the cowl, recessed within an opening to keep it out of the sun, and where it would not be subject to engine heat?…say somewhere in the slot opening above my port circular inlet for port radiator?…(we’re looking at a liquid cooled engine installation).

Fred.

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davidjoyce(at)doctors.org
Guest

Posted: Sat Oct 04, 2014 9:16 pm Post subject: OAT probe location

Fred, had not appreciated that you have fancy fairings! 

However I guess a nearby position through the lower 

surface of the fuselage or the fairing on the starboard 

side would serve.

Regards, David

On Sat, 4 Oct 2014 15:17:30 -0700

  Fred Klein <fklein(at)orcasonline.com> wrote:

 	  Quote: 	
		   

 On Oct 4, 2014, at 2:40 PM, David Joyce 

<davidjoyce(at)doctors.org.uk> wrote:

 

> Fred, It works nicely just in front of the starboardflap 

>activator slot, hidden by wing root from sun, but in full 

>contact with outside air between flap end & fuselage. 

>Starboard to avoid exhaust fumes. 

 

 David…your suggestion much appreciated…however, you will 

note in attached photos that on my ship, the slot gets 

buried within my enhanced wing root fairings. I fear that 

the probe will reach interior cockpit / aft fuselage 

temps. Care to comment on whether my fears are 

justified?…

 

 Any suggestion (anyone!) for an alternate location…?...

 

> PS Before I accept, how big is the kingdom and how surly 

>are the natives?

 

 My kingdom is a very small part of a small rock in the 

Salish Sea just south of Vancouver, B. C., and the 

natives can be very surly, especially when they’re 

restless.

 

Fred

> 

> On Sat, 4 Oct 2014 14:13:12 -0700

> Fred Klein <fklein(at)orcasonline.com> wrote:

>> 

>><fklein(at)orcasonline.com>

>> All,

>> I offer half my kingdom to anyone who will give me a 

>>proven location for an OAT thermocouple which is part of 

>>my “aftermarket” EMS.

davidjoyce(at)doctors.org
Guest

Posted: Sat Oct 04, 2014 9:21 pm Post subject: OAT probe location

Fred, There is the issue of ram air compression raising 

the temp. I have an airbox temp sensor as well as the wing 

root sensor and although they say the same thing before 

engine start, the air box one rises appreciably, possibly 

10C in flight. Regards, David, GXSDJ



On Sat, 4 Oct 2014 15:50:54 -0700

  Fred Klein <fklein(at)orcasonline.com> wrote:

 	  Quote: 	
		   Has anyone place an OAT probe at the front of the cowl, 

recessed within an opening to keep it out of the sun, and 

where it would not be subject to engine heat?…say 

somewhere in the slot opening above my port circular 

inlet for port radiator?…(we’re looking at a liquid 

cooled engine installation).

 

Fred.

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 04, 2014 9:41 pm Post subject: OAT probe location

On Oct 4, 2014, at 10:16 PM, David Joyce <davidjoyce(at)doctors.org.uk (davidjoyce(at)doctors.org.uk)> wrote:

 	  Quote: 	
		  a nearby position through the lower surface of the fuselage or the fairing on the starboard side would serve. 	




Thank you David.

Best,

Fred



 [quote][b]

Paul M 383

Joined: 19 Mar 2012
Posts: 97
Location: United Kingdom

Posted: Sun Oct 05, 2014 12:00 am Post subject: Re: OAT probe location

How about the stbd fuel tank outlet access panel? If it didn't work out you could reposition it, without having to patch a hole in the fuse...



Paul M

383 XS Mono 912s

Remi Guerner

Joined: 14 Dec 2010
Posts: 284

Posted: Sun Oct 05, 2014 12:44 am Post subject: Re: OAT probe location

Fred,

My OAT probe is installed inside the air intake of the Rotax cylinder cooling baffle. Pic attached. It works fine in flight, the measured error being less than one degree C.

However, during ground operation, the indicated temperature is useless as it is greatly influenced by the engine heat.  

This works for me.

Regards

Remi 

F-PGKL

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alanb(at)dpy01.co.uk
Guest

Posted: Sun Oct 05, 2014 1:13 am Post subject: OAT probe location

Mines installed in the air intake for the radiators and works for me. I certainly don’t see the ram air effect raising the temperature.



Alan

G-OBJT

On 5 Oct 2014, at 09:44, Remi Guerner <air.guerner(at)orange.fr> wrote:



 	  Quote: 	
		   

 

 Fred,

 My OAT probe is installed inside the air intake of the Rotax cylinder cooling baffle. Pic attached. It works fine in flight, the measured error being less than one degree C.

 However, during ground operation, the indicated temperature is useless as it is greatly influenced by the engine heat.  

 This works for me.

 Regards

 Remi 

 F-PGKL

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=431518#431518

 

 

 

 

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h&jeuropa

Joined: 07 Nov 2006
Posts: 645

Posted: Sun Oct 05, 2014 4:26 am Post subject: Re: OAT probe location

Fred,



Ours is just tie wrapped to wires in the space covered by the starboard wing fairing aft of the spar and works fine. Our fairing is taped to the fuselage but the rear end is open, not sealed like yours.  We had it in the fairing for the port flap cross tube hinge (FL18) but it got a lot of heat from the exhaust.



Heather reports the forward face of the starboard footwell stays comfortable with our 914 setup since it gets air from the inlet for the turbo but that probably is different on your Subaru setup.



How about locating it in the access panel on the starboard side under the starboard tailplane?



Jim & Heather

budyerly(at)msn.com
Guest

Posted: Sun Oct 05, 2014 6:16 am Post subject: OAT probe location

Fred,

I have seen a number of installations and tried a few myself.



Flap area as you have heard works well.

Just aft of the rear wing attach (good airflow through the pip pin hole I 

guess).

At the fairing for the stabilator just forward of the metal bracket TP12. 

If centered it doesn't interfere with the stab.

In the tail post lower end, in a trigear with the bottom of the rudder cut 

off as per the manual.

Under the passenger seat near the wing fillet out in the stream.  (Retrofit 

idea it put the magnatometer and OAT together under the pax seat.  Quick and 

easy worked great. On autopilots installed though.)

In a NACA duct coming into the cockpit.  The duct was equipped with a plenum 

off the NACA to allow ball type inlet control, and this gave room for the 

probe.

In a tail fin mounted NACA duct which funneled air up to the cockpit.

In the 914 engine inlet metal duct work just forward of the air filter.

    Note that his is subject to the  heated duct and must be insulated from 

that heat transfer.  Terrible on the ground between sorties.

In the 914 duct on the vertical metal below the oil tank.  (Ran high all the 

time.)

In the 912 XS Airbox.  Just under the filter in the fiberglass box, it is 

not bad but is just a bit warmer than outside air, better if attached just 

in the free air coming into the filter on the top of the airbox where it can 

sense the NACA airflow coming into the engine...

    Note, same problem on the ground above.

In the metal air inlet face just inside the fiberglass cowl on the XS.

    Note, same problem on the ground as above.  Lots of bugs too.

In a custom made flap bracket cover on the starboard side (a modified 

teardrop, with a 1/4 inch hole dedicated to allow air to impact the probe 

and go out through a vent in the rear of the teardrop.)   Nicely done. 

Supposedly worked and I can't see why not.



The above positions all worked in-flight OK.



Lessons learned:

Anything in the tail meant more wire, voltage drop and weight.

Anything in the engine, meant insulation from heat.

Anything on the outside of the skin meant hitting it when washing.  Not 

unlike civil air probes.  They just stick it out the side of the aircraft 

where convenient.

Anything on the gaps in the flight controls meant extreme care to assure no 

interference.



Not so well working:

Mounted on top of the aircraft near the fuel vents in a mono.  The sun 

heated it and it was always high in the summer and just OK in winter.

In the port wing near the end of the flap in a Classic.  Hot exhaust must 

collect under the wing or something.  Plus it was another connector to 

disconnect.  I had to move this clients probe to the starboard side.

In the cockpit tunnel for the mono forward of the gear just below the panel. 

Seems hot air coming in from the leaky firewall was the culprit.  Moved to 

belly.



Good luck Fred.

Regards,

Bud



--------------------------------------------------

From: "Fred Klein" <fklein(at)orcasonline.com>

Sent: Saturday, October 04, 2014 5:13 PM

To: <europa-list(at)matronics.com>

Subject: OAT probe location



 	  Quote: 	
		   



 All,



 I offer half my kingdom to anyone who will give me a proven location for 

 an OAT thermocouple which is part of my “aftermarket” EMS.



 with appreciation,



 Fred

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sun Oct 05, 2014 2:16 pm Post subject: OAT probe location

All…thank you very much for all the thoughtful replies…many good choices indeed…Fred

budyerly(at)msn.com
Guest

Posted: Mon Oct 06, 2014 7:07 am Post subject: OAT probe location

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Fred,



<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->                        [img]cid:00eb01cfe177$05a63450$266A5CEF(at)BudsPC[/img][img]cid:00ec01cfe177$05a63450$266A5CEF(at)BudsPC[/img] Photo E-mail           View slideshow        | Download images           That's why its called Custom Flight.   We do all this kind of  stuff based on the needs and wants of the client.  Does it add  speed..No.  Just costs more time.

 While doing the inlet for the teardrop Fred, you might as well add a bit of  an extension for it to cover those 525s that stick out.  Get it all done at  once.

  

                   [url=C:\Documents and Settings\Administrator\My Documents\Wheel Pants\IMG_20141006_104202_503.jpg][img]cid:00ed01cfe177$05a63450$266A5CEF(at)BudsPC[/img][/url]

               

    

  

 Regards,

 Bud

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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Mon Oct 06, 2014 10:33 am Post subject: OAT probe location

On Oct 6, 2014, at 8:05 AM, Bud Yerly <budyerly(at)msn.com (budyerly(at)msn.com)> wrote:

 	  Quote: 	
		  That's why its called Custom Flight.   We do all this kind of stuff based on the needs and wants of the client.  Does it add speed..No.  Just costs more time.

While doing the inlet for the teardrop Fred, you might as well add a bit of an extension for it to cover those 525s that stick out.  Get it all done at once.

	


Bud…those look terrific…I had no idea you made them up…as for “time cost”, tis in the mind of the builder!



They look very similar to mine, courtesy of Kingsley Hurst…pix below.

Thanks again for the tip of placing my OAT within.

Cheers,

Fred

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rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Oct 10, 2014 2:08 am Post subject: Re: OAT probe location

Thanks to Kevin Horton in the RV group who looked this up:

COmpression heating or ram air heating can be calculated as:

 TAS in kt, and temperatures in deg C:



IOAT = OAT + ((K * TAS^2)/7592)



OAT = Outside air temperature

IOAT = indicated OAT (i.e. the value you actually see on the OAT indicator)

K = OAT probe recovery factor - usually somewhere between 0.8 and 1, if the probe is truly stuck out in the airflow.

Therefore, in a Europa. don't expect more than about a 2Â°C change in OAT

reading. At 200 kts, expect roughly 4Â°C

_________________
Ira N224XS

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