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Avionics cooler

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trigo(at)mail.telepac.pt
Guest

Posted: Mon Jan 01, 2007 2:44 pm Post subject: Avionics cooler

Has anyone ever installed (even if not, I'd also like to hear your opinion) 

an avionics cooler, like this one from AmerI-King, in an OBAM airplane?

What's your opinion on this?

 - Is it only necessary when you operate in hot climates?

 - Which avionics do need this cooling? Xpdr, Comm radio, EFIS, GPS, 

Auto-Pilot controller?

 - Is it mounted vertically, horizontally or either?

 - Is it sufficient to use air from inside the cockpit as the source, or is 

it necessary to bring fresh air from the aircraft's exterior ?

 - Should it be ON everytime the avionics are ON, or should it have an 

independent On-Off switch? Is there any kind of thermostatic automatic 

switch ?



Uff ! Enough questions for now, and TIA for the answers

Carlos

sarg314(at)comcast.net
Guest

Posted: Mon Jan 01, 2007 3:13 pm Post subject: Avionics cooler

Carlos, I have installed a "ice box" 3-port fan  unit from Aircraft 

Spruce, I think.  I will use it to cool the SL-30 (nav/com), the Garmin 

transponder,  and the Dynon D10A.  I am not flying yet.  I was 

reluctantly convinced to do this after talking to engineers at Garmin 

and Dynon.  They didn't say it was necessary, but they recommended it.  

The Dynon guy sounded like he'd been burned by heating problems.  Having 

been in the electronics business, I know that cooling can significantly 

extend the life time of electronics.  I do live in Arizona, so it gets 

hot here.



I mounted the fan on the cabin side of the firewall recess (Ken at Van's 

suggested that spot, actually) right above the rudder pedal tubes.  It 

will run whenever the main switch is on. If I am running off the 

essential bus, the fan is not powered.



It draws in ambient cabin air.  It's mounted with the 3 tubes pointing 

up.  Just having moving ambient air blowing across the electronics is 

what's important.  You don't have to go to great lengths to get cold 

air, though it would obviously help. 

--

Tom S., RV-6A.

rv9jim(at)juno.com
Guest

Posted: Mon Jan 01, 2007 3:38 pm Post subject: Avionics cooler

Hi Carlos,

        I have a Garmin transponder that "recommends" additional cooling.

 I purchased a small "Shack" 12 volt squirrel cage fan and mounted it

under my panel behind the transponder. I'm building an RV so I have a bit

of room behind the Xpndr.  I made some light weight brackets to hang it

horizontal (bottom feed) from one of the vertical ribs that go from the

fire wall to the panel.  I then made up a custom fiberglass "tube" to get

the air from the fan to the Xpndr.  The tube also mates the square output

from the fan to the round input at the Xpndr.

        As an aside, I installed a cooling fan on my first build because

it was a bit crowded behind the panel.  I again used a "shack" squirrel

cage fan and directed the air between the transmitter and the Xpndr. 

Worked find for over three years + .



Jim Nelson

ceengland(at)bellsouth.ne
Guest

Posted: Mon Jan 01, 2007 5:49 pm Post subject: Avionics cooler

Carlos Trigo wrote:



 	  Quote: 	
		   

 <trigo(at)mail.telepac.pt>



 Has anyone ever installed (even if not, I'd also like to hear your 

 opinion) an avionics cooler, like this one from AmerI-King, in an OBAM 

 airplane?

 What's your opinion on this?

 - Is it only necessary when you operate in hot climates?

 - Which avionics do need this cooling? Xpdr, Comm radio, EFIS, GPS, 

 Auto-Pilot controller?

 - Is it mounted vertically, horizontally or either?

 - Is it sufficient to use air from inside the cockpit as the source, 

 or is it necessary to bring fresh air from the aircraft's exterior ?

 - Should it be ON everytime the avionics are ON, or should it have an 

 independent On-Off switch? Is there any kind of thermostatic automatic 

 switch ?



 Uff ! Enough questions for now, and TIA for the answers

 Carlos 


	




Cabin air will avoid the risk of raining on your avionics.



Charlie

nuckollsr(at)cox.net
Guest

Posted: Tue Jan 02, 2007 8:14 am Post subject: Avionics cooler

At 10:42 PM 1/1/2007 +0000, you wrote:



 	  Quote: 	
		  

<trigo(at)mail.telepac.pt>



Has anyone ever installed (even if not, I'd also like to hear your 

opinion) an avionics cooler, like this one from AmerI-King, in an OBAM 

airplane?

What's your opinion on this?

- Is it only necessary when you operate in hot climates?


	


   Difficult to answer because so much is dependent upon"

   how many radios are in your stack? . . . how well does

   air circulate around them naturally? Does your cabin

   heat outlet blow on the radios in cool weather?



   The only solid answer to necessity for external cooling

   is to conduct worst case conditions cooling tests with

   thermocouples. This is impractical for the vast majority

   of OBAM aircraft projects so the alternative is to

   add blowers if there are any doubts as to the welfare

   of tightly packed stacks of radios or any other electronics.

 	  Quote: 	
		  - Which avionics do need this cooling? Xpdr, Comm radio, EFIS, GPS, 

Auto-Pilot controller?


	


   In the early beginnings of the solid state radio days,

   there was a common misconception that since transistor

   radios ran cooler, that the need for forced air cooling

   automatically went away.



   Problem was that the parts associated with fabricating

   any radio had about the same temperature limitations

   whether used for vacuum tube or silicon radios. Further,

   temperature rise within a radio was a function of WATT-DENSITY

   or watts/cubic-in. While silicon radios dissipated fewer

   watts internally, they were also MUCH more compact. It

   was not unusual to find that some solid state radios

   had worse internal hot-spots than did their vacuum

   tube ancestors.



   Whether or not any particular radio is vulnerable to

   suffocation needs to come from the manufacturer. Instrument

   panel mounted equipment for small aircraft would be qualified

   under Category A1 for temperature/altitude. This is +55C

   ambient and 15,000 feet. Check the devices you're installing

   for their DO-160 qualification ratings.



   Lots of older transponders and DME transceivers

   were fitted with a dedicated blower duct attachment

   right on the back of the radio and external cooling

   required as part of the certified installation.

   Except for the degree of circulation, a radio

   behind the panel is breathing the same air as

   you and +55 is really toasty!



   It doesn't hurt to cool things but I'd be surprised

   if any modern hunk of electronics will need it

   in an OBAM light plane.



 	  Quote: 	
		  - Is it mounted vertically, horizontally or either?


	


   Cooling fans are not orientation sensitive . . .



 	  Quote: 	
		  - Is it sufficient to use air from inside the cockpit as the source, or is 

it necessary to bring fresh air from the aircraft's exterior ?


	


   Obviously, cooler is better . . . but be wary of external

   air sources. We filled a few radios with rain water due

   to poorly crafted duct drains when slip stream driven

   droplets propagated all the way into the radios.



   Unless your cooling air inlet is right next to your

   cabin heat outlet, cabin ambient air is sufficient.

   Recall that the effectiveness of cooling air has

   more to do with motion than with temperature

   differential. The most valuable task the cooling

   air blower can serve is to CIRCULATE air at

   almost any lower temperature.



 	  Quote: 	
		  - Should it be ON everytime the avionics are ON, or should it have an 

independent On-Off switch? Is there any kind of thermostatic automatic switch ?


	


   A switch (thermostatic or otherwise) not installed

   is not going to require future maintenance or be forgotten

   at a bad time. I'd recommend that cooling blowers be

   powered from the main bus and come alive anytime the

   airplane is powered up. I think that's what we do

   with all avionics cooling in the big ships. If there's

   a possibility that any radio is on, the blower(s) are

   on too. No switches.



   Bob . . .

trigo(at)mail.telepac.pt
Guest

Posted: Tue Jan 02, 2007 9:34 am Post subject: Avionics cooler

From: "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>



 	  Quote: 	
		  >- Is it only necessary when you operate in hot climates?



   Difficult to answer because so much is dependent upon"

   how many radios are in your stack? . . .


	


I will have 1 Comm Radio, 1 Transponder, 1 Garmin 296 and 1 Car radio/CD 

player in the stack, plus 1 single display EFIS and the Auto-Pilot control 

module.



 	  Quote: 	
		   how well does air circulate around them naturally?


	


I believe (I'm not sure) that air will not circulate naturally, or very 

little, behind my RV-9A panel.



 	  Quote: 	
		   Does your cabin heat outlet blow on the radios in cool weather?


	


No. Besides the "normal" fresh air outlets, which are in the usual places in 

side-by-side RV's, at the bottom corners of the panel, I will also have 2 

separate heat outlets, situated right below the others, which will heat the 

cabin, sourced from an hot coolant heater blower ( Eggenfellner Subaru 

engine)



 	  Quote: 	
		  >- Which avionics do need this cooling? Xpdr, Comm radio, EFIS, GPS, 

>Auto-Pilot controller?



   ......... Whether or not any particular radio is vulnerable to

   suffocation needs to come from the manufacturer. .....

  Check the devices you're installing  for their DO-160 qualification 

 ratings.


	


I will try to find that, however I am installing an ICOM A-200 (or perhaps, 

if permitted by future income, a GARMIN SL-30) and a NARCO AT-160 (or a 

GARMIN GTX-330, when mode S becomes mandatory in Europe).



 	  Quote: 	
		  >- Is it mounted vertically, horizontally or either?



   Cooling fans are not orientation sensitive . . .


	


OK, if I install it, I will try to avoid puting it horizontally with the 

inlet facing upwards, only to avoid the fan from throwing out dust or any 

screw that could fall from the avionics 



 	  Quote: 	
		  >- Is it sufficient to use air from inside the cockpit as the source, or is 

>it necessary to bring fresh air from the aircraft's exterior ?



   Obviously, cooler is better . . . but be wary of external

   air sources. We filled a few radios with rain water due

   to poorly crafted duct drains when slip stream driven

   droplets propagated all the way into the radios.


	


Yeah! Somebody else has already warned me against that possiblity



 	  Quote: 	
		  >- Should it be ON everytime the avionics are ON, or should it have an 

>independent On-Off switch? Is there any kind of thermostatic automatic 

>switch ?



   A switch (thermostatic or otherwise) not installed

   is not going to require future maintenance or be forgotten

   at a bad time. I'd recommend that cooling blowers be

   powered from the main bus and come alive anytime the

   airplane is powered up. I think that's what we do

   with all avionics cooling in the big ships. If there's

   a possibility that any radio is on, the blower(s) are

   on too. No switches.


	


Not even to have the possibility to turn it Off in a 

no-alternator-low-battery-power emergency situation?



Thanks

Carlos

Gilles.Thesee(at)ac-greno
Guest

Posted: Tue Jan 02, 2007 10:06 am Post subject: Avionics cooler

 	  Quote: 	
		  >  I'd recommend that cooling blowers be

>   powered from the main bus and come alive anytime the

>   airplane is powered up....



 Not even to have the possibility to turn it Off in a 

 no-alternator-low-battery-power emergency situation?



Carlos and all,
	




In that case, you'll be on E-bus only, so the fan will be off since it 

is powered from the main power bus.

Or did you install no E-bus at all ?



Best wishes to all,



Regards,

Gilles Thesee

Grenoble, France

http://contrails.free.fr

nuckollsr(at)cox.net
Guest

Posted: Tue Jan 02, 2007 10:15 am Post subject: Avionics cooler

At 05:28 PM 1/2/2007 +0000, you wrote:



 	  Quote: 	
		  

<trigo(at)mail.telepac.pt>



From: "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>



  <snip>



>>- Should it be ON everytime the avionics are ON, or should it have an 

>>independent On-Off switch? Is there any kind of thermostatic automatic switch ?

>

>   A switch (thermostatic or otherwise) not installed

>   is not going to require future maintenance or be forgotten

>   at a bad time. I'd recommend that cooling blowers be

>   powered from the main bus and come alive anytime the

>   airplane is powered up. I think that's what we do

>   with all avionics cooling in the big ships. If there's

>   a possibility that any radio is on, the blower(s) are

>   on too. No switches.



Not even to have the possibility to turn it Off in a 

no-alternator-low-battery-power emergency situation?


	


     If cooling is on the main bus and devices

     needed for comfortable termination of flight

     are on the e-bus, then cooling is one of those

     loads automatically shed when the alternator

     is inoperative.



     Bob . . .

trigo(at)mail.telepac.pt
Guest

Posted: Tue Jan 02, 2007 4:28 pm Post subject: Avionics cooler

Bon soir Gilles

(Fait-il beaucoup de froid à Grenoble?)



My system is based on the ExpBus, which in case you don't know, is a 

premanufactured electric buss system (which, by the way, 'letric Bob doesn't 

recommend).

But since my system has a Main Battery buss and an Aux Battery buss, I will 

connect it to the Main, therefore it will also be OFF in case of an electric 

emergency.



Carlos

---

trigo(at)mail.telepac.pt
Guest

Posted: Tue Jan 02, 2007 4:38 pm Post subject: Avionics cooler

Tom S., James H., Charlie E., Bob N.



Thanks for your input. I will try to measure the panel back temperature with 

all the avionics paraphernalia already working (which will only happen, very 

conveniently, in the next summer) and I'll decide accordingly.



Carlos

Speedy11(at)aol.com
Guest

Posted: Tue Jan 02, 2007 6:16 pm Post subject: Avionics cooler

 	  Quote: 	
		  Has anyone ever installed (even if not, I'd also like to hear your opinion) 

an avionics cooler 	
  

 Carlos,

 I have the same experience as Tom S.  The avionics manufacturers said that while a fan is not required, it will extend the life of the avionics.  Also, a local avionics expert advised me to install one.  So, I'm listening to the experts - despite the cost and weight.

 As with Tom, mine will also cool the SL-30, transponder and EFIS using ambient air.  It will be on anytime the main bus has power.  It will be mounted behind the panel.

 Stan Sutterfield

 Do not archive

  [quote][b]

Gilles.Thesee(at)ac-greno
Guest

Posted: Wed Jan 03, 2007 4:16 am Post subject: Avionics cooler

 	  Quote: 	
		   (Fait-il beaucoup de froid à Grenoble?)



 My system is based on the ExpBus, which in case you don't know, is a 

 premanufactured electric buss system (which, by the way, 'letric Bob 

 doesn't recommend).

 But since my system has a Main Battery buss and an Aux Battery buss, I 

 will connect it to the Main, therefore it will also be OFF in case of 

 an electric emergency.


	


Hi Carlos,



Winter is not really there in Grenoble, and most ski resorts are still 

closed due to the lack of snow. Are you located in Portugal ?

I've heard about the ExpBus. The Aux Battery bus may play the same role 

as an E-bus.



Best regards,

Gilles

http://contrails.free.fr

nuckollsr(at)cox.net
Guest

Posted: Wed Jan 03, 2007 6:07 am Post subject: Avionics cooler

At 12:37 AM 1/3/2007 +0000, you wrote:



 	  Quote: 	
		  

<trigo(at)mail.telepac.pt>



Tom S., James H., Charlie E., Bob N.



Thanks for your input. I will try to measure the panel back temperature 

with all the avionics paraphernalia already working (which will only 

happen, very conveniently, in the next summer) and I'll decide accordingly.


	


   As a gemeral rule of thumb, you can do your temperature tests

   at any convenient time and extrapolate for worst case. For example,

   if your tests at 25C ambient produces a temperature of 45C at some

   point of interest, the same point measured at 35C ambient would

   also be 10 degrees higher or 55C.



   Bob . . .



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

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

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

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