Very good point about the reflector oxidation. I guess I should paint
it right away with reflective paint.
I looked at the solid state breakers you refer to. They are made of a
polymer, which opens the circuit when its temperature gets above a
preset limit. The reason I decided not to use those is because it is
strongly dependent on the ambient temperature. ie it will trip at
different currents when it is cold outside vs hot outside. This could
be a problem since the aircraft is likely to see large swings in
temperature from winter to summer, and at different altitudes. The
filament fuses are in a sealed glass tube, which is relatively
independent of temperature.
Mechanical vibration... The LEDs don't care about mechanical vibration
as much as regular lamps do. The electronics are all solid state, so
they won't care either. The solder joints might care, but if that were
the case, all other electronics in the cockpit will also be vulnerable.
I've built other electronics for the cockpit, and never had vibration
related problems. I could be wrong. I guess I will find out.
Thanks for your pointers. I will have to take them into
consideration...
Dan wrote:
Andrew Sarangan wrote:
Recently I designed and built a nav light system for my Europa aircraft
using the Luxeon LEDs with great results.
I also measured the radiation pattern (after fitting the LEDs to the
aircraft) and compared it to the FAR specs. It exceeds the requirements
by 3-5 times, and draw only 2 Amps total. It is bright enough to almost
use as a landing light.
Actually, I am surprised that most manufacturers do not provide a
measured radiation pattern. They just say that it complies with the
FAR. Well, meeting the specs is not the same as exceeding it. Since
LEDs lose power with age, this could be an important consideration.
Just in case someone might find this useful, I wrote it up as an
article:
http://www.sarangan.org/aviation/eur...tip-Lights.pdf
Let me know what you think.
3 questions:
1) are the electronics going to survive vibration? I don't see any
isolation.
2) won't the reflector tend to oxidize fairly rapidly?
3) why use a fuse? Jim Weir did a rather nice article in KitplanesŪ
awhile back discussing a solid state circuit breaker (I forget what it's
called) that might be a good idea.
I rather like the set up. Very good write up 
Dan, U.S. Air Force, retired