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windscreen air

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Fergus Kyle

Joined: 03 Jun 2007
Posts: 291
Location: Burlington ON Canada

Posted: Tue Nov 16, 2010 7:56 am Post subject: windscreen air

Graeme,  

        I followed the others and installed a ~2” computer fan aligned in the middle of the port seat andthree inches back from the instrument panel front to whisk away heat from my Dynon screen AND hopefully prevent/overcome misting. Easy, simple, switched and hopefully effective.  

Cheers, Ferg    [quote][b]

rampil

Joined: 04 May 2007
Posts: 870

Posted: Tue Nov 16, 2010 10:26 am Post subject: Re: windscreen air

I would wait for people actually flying with these fans in condensing

or overheating conditions to report the result of their use before deciding what to do.



After a very warm summer in my neck of the woods, I installed a fan

over my BMA EFIS into a louver pointed at the plexi.



At best, it prolongs the time to EFIS internal temp of 145F by about 15%

meaning from (out of the sun 90F) to 145F flying in sun now takes

about 30 min instead of 25 min. The BMA displays internal temp and shuts

off at 153 or so.  Lucky, in the soup it is never that warm!



To be a useful amount of cooling air in my glass panel system, I am

looking at a straight dump of an outside air vent into the panel on the hottest days to be effective given the IR energy and electric load into the panel.  All these pretty little fan setups may work fine on a sunny day

in Alaska but not Lakeland Florida.

_________________
Ira N224XS

kheindl(at)msn.com
Guest

Posted: Tue Nov 16, 2010 10:34 am Post subject: windscreen air

Is mist on the windscreen really a problem ? I am asking because I never noticed any on mine.



Cheers,

Karl

From: VE3LVO(at)rac.ca

To: europa-list(at)matronics.com

Subject: windscreen air

Date: Tue, 16 Nov 2010 10:51:01 -0500



       Message body     

Graeme,  

        I followed the others and installed a ~2” computer fan aligned in the middle of the port seat andthree inches back from the instrument panel front to whisk away heat from my Dynon screen AND hopefully prevent/overcome misting. Easy, simple, switched and hopefully effective.  

Cheers, Ferg    [quote]



_blank">www.aeroelectric.com

" target="_blank">www.buildersbooks.com

="_blank">www.homebuilthelp.com

="_blank">http://www.matronics.com/contribution

 target="_blank">http://www.matronics.com/Navigator?Europa-List

http://forums.matronics.com

[b]

fklein(at)orcasonline.com
Guest

Posted: Tue Nov 16, 2010 10:51 am Post subject: windscreen air

 	  Quote: 	
		   All these pretty little fan setups may work fine on a sunny day in  

 Alaska but not Lakeland Florida.


	


To All (of those of us who are flying)...



Still being just a builder, I'd love to hear more on this subject. My  

understanding is there are two separate issues...the first being the  

ability to blow some warm air on the windshield in order to de-mist,  

and the second being the ability to cool the avionics.



Perhaps the little fans can't do both...(?)



Fred

rampil

Joined: 04 May 2007
Posts: 870

Posted: Tue Nov 16, 2010 5:45 pm Post subject: Re: windscreen air

Hi Fred,



Its all a question of degree!



It is a question of moving heat from on place to another. I don't

think the fans would ever need to clear the screen and remove

excess heat from the panel at the same time. How cold is the screen

below dew point, how many calories needed to warm it above dew point

versus how many calories are sucked out, cooling the outside of the

screen via the airstream?



How many calories need to be pulled out of the panel per minute to

match or exceed the IR load dumped into it from the sun.



Either way air does not carry many calories per cubic foot, so you

need to move lots of them

_________________
Ira N224XS

fklein(at)orcasonline.com
Guest

Posted: Tue Nov 16, 2010 6:12 pm Post subject: windscreen air

On Nov 16, 2010, at 5:45 PM, rampil wrote:



 	  Quote: 	
		   How many calories need to be pulled out of the panel per minute to

 match or exceed the IR load dumped into it from the sun.



 Either way air does not carry many calories per cubic foot, so you

 need to move lots of them


	


Hi Ira...you're gettin beyond my bandwidth...in your previous post, it  

seemed to me that your fan installation was for avionics cooling, and  

I surmised that you achieved but modest improvement.



Do you ever encounter windshield fogging or misting, and if so, what  

have you done or plan to do to alleviate it? (I take it you're not  

expecting your fan to do very much.)



Fred

gholland(at)content-strea
Guest

Posted: Tue Nov 16, 2010 9:28 pm Post subject: windscreen air

Fred

Here in UK I have experienced windscreen misting in two different Europa's.

When I built mine I was conscious that air needed extracting through the

rear on panel area to reduce by removing some warmer air created by the

various panel systems. At the same time it occurred to me and at least one

significant other (Paddy!) that it could prove useful if the extraction fans

blew across face of front screen. It did prove to be the case and to work,

certainly within a 5-10 minute start up and taxi cycle.

The side windows are not reached by the fans airflow and they still remain

misted and have to be wiped with absorbent cloth to remove that moisture.

Both Aircraft had overhead Air Vents using flip up air dam in cabin roof.

That proves useful but mainly to reduce inside temperature in summer. It

works very well once underway. I also added warm air system and that too

added to cabin comfort in winter and reduce internal misting.

In climates such as UK in winter with a range between -5C and 15C and a

range of humidity on any day from September to April, misting is a feature

of the Europa cabin and certainly needs addressing. Take off in IMC just due

to condensation is not an experience I personally need! The Cabin clears

after a few minutes if any residual misting left in corner areas due to

natural leaked airflow in fuselage. Sorry to ramble but in short. Fit Fans

if you can with a switched supply and those using EXPBus can also easily

control speed of Fans. These Computer Fans are quiet and certainly produce

some good airflow.

Regardless of theories it worked for me!

I now fly an open cockpit aircraft and even here my bloody goggles sometimes

mist up. Local comment is that my flying improves significantly during these

periods!

In the words of Oscar Wilde....Demist or be damned!

Yes I have just taken my pills!

Regards

Gerry



Gerry Holland

07808 402404

gholland(at)content-stream.co.uk

Based at White Ox Mead, Near Bath, UK

davidjoyce(at)doctors.org
Guest

Posted: Wed Nov 17, 2010 1:41 am Post subject: windscreen air

Like Ira I have a BMA Efis and a medium sized fan (over passenger footwell) 

with a row of holes under pilot windscreen. It works moderately well in 

terms of demisting, where I suspect that you only need to warm the air by a 

few degrees to have an effect. It does not stop the Efis complaining about 

overheating in central Spain in a heatwave (where I experienced air box temp 

of 37.4 C/100F). I have found that in such temps the top of the instrument 

module which is painted dark blue, gets unpleasantly hot to touch, and 

dealing with that factor is probably more important than the internal air 

flow. I have a piece of neoprene with one silvered surface which I place on 

top in such conditions, but if I was starting again I would consider 

building in some insulation over that top surface and also having the fan. 

Regards, David Joyce, G-XSDJ

rampil

Joined: 04 May 2007
Posts: 870

Posted: Wed Nov 17, 2010 7:18 am Post subject: Re: windscreen air

Hi Fred,



I have not seen plexi condensation since I install the fan this summer.

Could be the fan or the weather conditions so far.



I speculate, not having actually measured the wind screen temperature, etc,

that the fan could help but it would be slow to effect change.



That is why I keep a Sontara (Dupont) cloth in the cockpit.



It works instantly   and does not make noise!

_________________
Ira N224XS

John Wighton

Joined: 18 May 2010
Posts: 242

Posted: Wed Nov 17, 2010 9:27 am Post subject: Re: windscreen air

Hi, What type of Sontara cloth do you use?



I contributed some pictures to a previous thread on the subject of demisting fans - pictures are on my post at http://forums.matronics.com/viewtopic.php?t=74836&highlight=



The fans work really well in the UK, last week it was cold and the entire cockpit misted up.  The fans cleared the important front LH screen immediately (l now leave them on permanently).  



Life saver.



Regards

JW

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