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windscreen de-fogging

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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Thu Jul 04, 2013 9:12 am Post subject: windscreen de-fogging

Gentlemen,



I'm attempting to select a couple of computer fans to be mounted louvers in the top of the instrument panel module for the purpose of de-fogging the windscreen...I'm uncertain as to what cfm ratings or sizes will do the job.



If anyone can pass on their experience w/ what amount of airflow is sufficient...or insufficient...I'd be grateful



I suspect that my local climate in the Pacific NW of the US is similar to conditions in UK.



Thanks in advance,



Fred

A-194

frans(at)privatepilots.nl
Guest

Posted: Thu Jul 04, 2013 9:43 am Post subject: windscreen de-fogging

On 07/04/2013 07:12 PM, Fred Klein wrote:



 	  Quote: 	
		   I'm attempting to select a couple of computer fans to be mounted

 louvers in the top of the instrument panel module for the purpose of

 de-fogging the windscreen...I'm uncertain as to what cfm ratings or

 sizes will do the job.


	


I did that too, and despite our damp climate I have used them only twice

(and found out that they didn't contribute much anyway).



You'd probably better save the weight.



Frans

Gilles.Thesee(at)ac-greno
Guest

Posted: Thu Jul 04, 2013 9:59 am Post subject: windscreen de-fogging

Fred Klein a écrit :

 	  Quote: 	
		   



 Gentlemen,



 I'm attempting to select a couple of computer fans to be mounted louvers in the top of the instrument panel module for the purpose of de-fogging the windscreen...I'm uncertain as to what cfm ratings or sizes will do the job.



 If anyone can pass on their experience w/ what amount of airflow is sufficient...or insufficient...I'd be grateful



 I suspect that my local climate in the Pacific NW of the US is similar to conditions in UK.



   


	


Hi Fred,



Here is what we did recently :

http://contrails.free.fr/cellule_defog_en.php



Not much weight involved (about 700-800 g) though we feel that our 380 

kg four seater is a bit on the heavy side 



FWIW,

Best regards,

-- 

Gilles

http://contrails.free.fr

rparigoris

Joined: 24 Nov 2009
Posts: 805

Posted: Thu Jul 04, 2013 10:12 am Post subject: windscreen de-fogging

Hi Fred 

 	"If anyone can pass on their experience w/ what amount of airflow is sufficient...or insufficient" 

 	I chose to use four 12 volt mini fans. They are run off a 3 position (low, high and off). If 2 are put in series it's low, and if run off bus voltage, then high. Yes idea as a minimiist demister but also to get heat out from under instrument module. You can find info on what I am doing (I did quite a bit of fooling with different fans. There is also a folder on that page "Panel cooling and demisting ideas by others." 

 	http://www.europaowners.org/main.php?g2_itemId=27305 

 	I am installing temp probes under the instrument module so will be able to see temps. 

 	Ron Parigoris    [quote][b]

budyerly(at)msn.com
Guest

Posted: Thu Jul 04, 2013 11:35 am Post subject: windscreen de-fogging

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

 I installed both 40 mm and 80 mm computer CPU fans and frankly, the 40s  don't move that much air.  The 80s do better at venting the hot air out of  the panel.  Some electronics get quite warm and I wanted to cool the panel,  not really defrost.  That was a hopeful side effect of the installation of  the fans.

  

 The first setup on 12AY I put the fans too far forward and they blow  into the windscreen support.  To be honest, I can't even feel the air flow  moving up the windscreen, it moves sideways.  That was a dumb execution of  a good idea.

  

 On others, I move the fans as far aft toward the pilot as I can  to pull the Garmin 430 and Dynon Skyview heat out of the panel.  They both  get pretty hot.  I have found that the air comes up the windscreen, but is  not hot enough or fast enough in the winter to feel like a defogger, but at  least it moves the air up the windscreen.  If you have an Ameriking type  cooling fan, one leg of that would be about as strong as my two 80s...   

  

 The Grand Rapids and Becker radios are pretty cool running and frankly the  panel only gets about 10 degrees warmer than the cockpit, so without the heat  and high forced air flow of an auto type defogger, I do not see it as much help  on a cold day at altitude with a quick descent to the warmer air below steaming  things up.

  

 Sorry I don't have more info for you.  It's just too hot here in  Florida.  Even in the winter, although my canopy top fogs up and my screen  fogs for a second or two, they both clear once the inside and outside  temps stabilize.

  

 Regards,

 Bud

 [quote]   ---

kevinmarie(at)blueyonder.
Guest

Posted: Thu Jul 04, 2013 11:40 am Post subject: windscreen de-fogging

I have no fans and it gets a little fogged up on the ground in the winter but I open the door and it clears. I never have any problems in the air and I have no heater.



Kevin Challis

G ODJG

Tri gear 912s

On 4 Jul 2013, at 19:12, Fred Klein <fklein(at)orcasonline.com> wrote:



 	  Quote: 	
		   

 

 Gentlemen,

 

 I'm attempting to select a couple of computer fans to be mounted louvers in the top of the instrument panel module for the purpose of de-fogging the windscreen...I'm uncertain as to what cfm ratings or sizes will do the job.

 

 If anyone can pass on their experience w/ what amount of airflow is sufficient...or insufficient...I'd be grateful

 

 I suspect that my local climate in the Pacific NW of the US is similar to conditions in UK.

 

 Thanks in advance,

 

 Fred

 A-194

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Jul 05, 2013 3:32 pm Post subject: Re: windscreen de-fogging

i have read the discussion on the issue of defogging and it appears that

are no actual answers out there yet regarding airflow, temperature, etc.



I will add my meager data to the pool



My bird has a Blue Mountain EFIS 4 series which shuts down at temps

above abt 144F. I have a 24 cfm fan in a convective tower directly

above the EFIS leading into a 3 in louver directed into the plexi.

On a 90F sunny day as so many local days are here on Long Island,

without the fan, the EFIS will blackout within an hour of the plane out 

of the hangar, flying or not. The installed fan slows the inexorable rise somewhat

say by 15 min to overheat. Clearly unacceptable cooling. However,

it has actually cleared plexi condensation in two instances where it existed,

in about 5 minutes (this was light grey mist, not dripping condensation).



As I contemplate my move to much warmer clime, i will need to

re-engineer the cooling. These little muffin fans are not likely to be useful

even if ganged together. High velocity outside air is probably the best answer. Actual flight testing is needed.



As usual, your mileage will vary



Ira

_________________
Ira N224XS

craigb(at)onthenet.com.au
Guest

Posted: Fri Jul 05, 2013 5:32 pm Post subject: windscreen de-fogging

You might want to try a couple of the 12v brushless DC fans, they range in

size from 30mm up to about 200mm

They move a lot of air for their size, like the ones you find in your

computer to ventilate the case



I had two network file servers running inside a closed cupboard total load

of about 1000w with a hole in the bottom

Back of the cupboard and one 100mm brushless DC fan to extract the air at

the top and didn't have an issue with them overheating



Worth a look at least, they normally run about $10 each, or free if you can

get your hands on a couple of old computers and pull them apart

To get the fans out of the power supply's



http://www.ebay.com.au/itm/2x-Brushless-DC-Cooling-Fan-12V-120mm-x-120mm-x-2

5m-/180729347608?pt=AU_Components&hash=item2a144efe18



this link just goes to one I found on ebay no doubt you could find your own



regards



craig

davidjoyce(at)doctors.org
Guest

Posted: Fri Jul 05, 2013 10:48 pm Post subject: windscreen de-fogging

Ira, I have a comparable system to keep my Blue Mountain 

EFIS happy, although my fan has inlet above pax feet and 

outlet through a dozen holes blowing on to pilot screen. 

Moderately effective as demister, but EFIS starts to 

complain when temps get up into vicinity of 35C (95 in 

your old units). I have found that laying a layer of 5mm 

neoprene with foil on one side, across top of panel (which 

is painted dark blue for visibility) cuts out direct sun 

heating and addresses the problem. So I have that Neoprene 

sheet available in the back and use it intermittently in 

exceptionally hot conditions

Regards, David Joyce, G-XSDJ



On Fri,  5 Jul 2013 16:32:15 -0700

  "rampil" <ira.rampil(at)gmail.com> wrote:

 	  Quote: 	
		   

<ira.rampil(at)gmail.com>

 

 i have read the discussion on the issue of defogging and 

it appears that

 are no actual answers out there yet regarding airflow, 

temperature, etc.

 

 I will add my meager data to the pool

 

 My bird has a Blue Mountain EFIS 4 series which shuts 

down at temps

 above abt 144F. I have a 24 cfm fan in a convective 

tower directly

 above the EFIS leading into a 3 in louver directed into 

the plexi.

 On a 90F sunny day as so many local days are here on 

Long Island,

 without the fan, the EFIS will blackout within an hour 

of the plane out 

 of the hangar, flying or not. The installed fan slows 

the inexorable rise somewhat

 say by 15 min to overheat. Clearly unacceptable cooling. 

However,

 it has actually cleared plexi condensation in two 

instances where it existed,

 in about 5 minutes (this was light grey mist, not 

dripping condensation).

 

 As I contemplate my move to much warmer clime, i will 

need to

 re-engineer the cooling. These little muffin fans are 

not likely to be useful

 even if ganged together. High velocity outside air is 

probably the best answer. Actual flight testing is 

needed.

 

 As usual, your mileage will vary

 

 Ira

 

 --------

 Ira N224XS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=404012#404012

 

 

 

 

 

 

 

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Duncan McFadyean

Joined: 18 Jan 2011
Posts: 224

Posted: Sat Jul 06, 2013 12:50 am Post subject: windscreen de-fogging

I took an air feed off the top of one of the side NACA ventilators,

primarily to squirt cool air over the back of the Terra transponder (which

(and the radios too) don't appreciate being cooked behind the standard

sealed Europa panel). There are slots cut in the top of the panel below the

bottom of the windscreen. It's not foolproof for demisting on the ground

(but a wiping cloth is!), but it does keep mist cleared in flight. I had one

computer fan previously, which worked similarly, but I took it out (heavy,

noisy, power consumer).



DMcF.



--

rampil

Joined: 04 May 2007
Posts: 870

Posted: Sat Jul 06, 2013 5:14 am Post subject: Re: windscreen de-fogging

David,



Thank you very much! Insulating reflective foam.

An Excellent suggestion 



Now, if I can just figure out how to keep myself from cooking in the cabin ....



Ira

_________________
Ira N224XS

craigb(at)onthenet.com.au
Guest

Posted: Sat Jul 06, 2013 3:13 pm Post subject: windscreen de-fogging

The 120mm brushless dc fan I linked to yesterday was supposed to move 25 CFM

and draw about .4 of an amp



Noise level 25db doesn't say what the weight is, but past experience I would

say it would be around 100g

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