Having had a couple of intermittent failures due to high
temperatures I'd like to pass on a method of keeping your instrument
panel cool on the ground before takeoff.
I was having trouble in our BD4 with the Dynon D10A giving me over
temp warnings on not very hot day even while flying. A little
consideration of the problem led me to conclude that having a matt
black expanse of glareshield/panel cover under an expanse of perspex,
turned down at the edges, front and rear isn't a really good idea.
Made worse in powered aircraft by heat leakage through the firewall.
GA radios etc are only rated to 55 deg C operating and the rule of
thumb in electronics is that mean time between failures halves for
very 10 deg C rise in average temperature.
Fortunately there is an easy fix. In the BD4 I installed a grill
instead of a solid access panel in the panel cover. Haven't had an
overtemp since on the Dynon, even on hot days. For gliders I suggest
a hole about 3"/80mm or so or several smaller ones (slots OK too) in
the top of the panel cover and black nylon insect screening (do use
plastic here, not metal as you've probably got GPS antennas under the
cover) glued in. Looks neat and will keep everything a lot cooler.
May prevent overt temporary failures due to over temp and will help
with long term longevity of all the electronics.
Also try to use a canopy cover until ready to takeoff and/or prop the
canopy open. Watch out for the front/rear hinged types as they have
been known to cause fires by reflecting the sun. Side hinged can blow
shut suddenly so you may want to devise a strut to hold open firmly.
I also wonder what this is doing to the composite in the cockpit structure.
After his first Australian summer a friend who emigrated from Germany
remarked that if the designers knew about temperatures here they'd be
using different resin systems/post cures of the composite structures.
May also explain why a lot of glider wings seem less stable here than
in other places as far as developing waviness.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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