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LEDs for Nav Lights - Jim Weir



 
 
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  #1  
Old February 15th 04, 10:45 PM
Scott Gettings
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Default LEDs for Nav Lights - Jim Weir

Jim & the group:

Most of us know how expensive navigation lights are for our aircraft.
When building in wingtip lights, many of us don't need the fancy light
housings that come with most STC'd light systems.

I've followed and enjoyed Jim's previous work on panel LEDs and various
topics over the years. I apologize in advance if I missed any previous
threads or discussion in my search on the use of LEDs as nav lights.

I've noted that several builders seem to be making progress with LED
navlights, especially since companies like Luxeon (below) have come out
with inexpensive, very high-intensity lights. Even some automotive
LEDs advertise they are putting out up to 150-200 cd. Other builders
are commercializing their LED products, but their prices are close to
the STC'd versions.

Jim, is it feasible for an average builder to integrate any of these LED
components into nav lights that will have acceptable performance?
Perhaps a Kitplane article to help all us electronically-challenged
builders?

Thanks in advance
Scott Gettings
Melbourne, FL




  #2  
Old February 15th 04, 10:49 PM
Scott Gettings
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Default

Here are the links that I intended as part of my first post. The "Send"
button is a dangerous thing 8-}

Scott Gettings


http://www.jbwilco.com/Cozyweb/navstrobe.htm
http://www.lumileds.com/luxeon/produ...cts_index.html
http://www.ledsupply.com/lib/ledsupply/02008a.pdf
http://www.ledsupply.com/led-catalog-luxeon-leds.html


Builders of LED systems:
http://www.creativair.com/ex75-nav/index.htm
http://www.killacycle.com/Lights.htm


Automotive-type high-output LCDs up to 200,000 mcd.
http://autolumination.com/specifications.html





  #3  
Old February 16th 04, 05:29 PM
Jim Weir
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Along with a degree in Semiconductor Physics comes a smattering of optics. Note
the word "smattering". I do not claim to have as detailed a knowledge of optics
as is necessary to prove to myself that any one design will in fact meet the FAA
requirements for (a) illumination pattern and (b) color. A minor failure in
either of these criteria, an incident or (even worse) accident traceable to the
failure to be seen at night and bingo, somebody gets to explain it to the man in
the black robe.

Having said that, you are correct. There are devices out there that would seem
to meet the requirements. I can evaluate the electronics of the design, make
any power source necessary for the operation of the design, but I cannot do the
optics part of the equation.

I've got a lab set up with just under $100K in electronic test equipment, but my
optics lab consists of a 1950s era photometer calibrated for f-stop and
fractional seconds and used with Kodak slide film. The point is that I'm more
than willing to work with somebody who DOES understand the optics part of the
requirements but needs the electronics handed to them as completed equipment.
No problem.

As yet, such a person has not leapt forward.

Jim


Scott Gettings
shared these priceless pearls of wisdom:

-
-Jim, is it feasible for an average builder to integrate any of these LED
-components into nav lights that will have acceptable performance?
-Perhaps a Kitplane article to help all us electronically-challenged
-builders?



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com
  #4  
Old February 17th 04, 02:53 AM
Jay
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The instruments to do those measurements are not expensive, about the
price of a set of landing lights from the Kill-a-cycle guy. So if you
want to make a hobby out of LED nav lights it might be interesting to
do. I've looked over what the Kill-a-Cycle guy is doing and he seems
to have done all the leg work for you and will even let you save some
money by doing your own soldering if you'd like.

Having said that, I would have done a few things different than he did
however to simplify the design and increase the efficiency.

1) You don't need regulators (or a slew of them) on the board, a stack
of light emmiting diodes and a resistor IS a regulator of sorts and
will do just fine in this application. Real light bulb nav lights
vary with supply voltage more than these ever will.

2) Partially because he went with the on board regulation, he gave up
the opportunity to provide a 14V/28V solder jumper to save power in
the 28V case. The current design just eats those extra 14V as heat
when used in a 28V system. In other words the 28V lights are 50% less
effiecent than the 14V application. But they both kick incadescants
butt for efficiency.

Regs- As is common in engineering, the spec is sometimes written AFTER
the design is completed, so they're basically just describing a sample
system that they like the performance of. So the reg as I rememebr
was very particular about intensity over angles, but for color just
said "red" and "green". So the real nav lights bleach out on the sun
and get more and more white over the years, while the LED sources will
give very pure (saturated) colors that do not change with time, but
you don't get any credit for having good color. You just have to use
a bunch of LEDs to make as much light as a light bulb behind a color
filter.





-Jim, is it feasible for an average builder to integrate any of these LED
-components into nav lights that will have acceptable performance?
-Perhaps a Kitplane article to help all us electronically-challenged
-builders?

 




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