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
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