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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 |
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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 |
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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
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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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