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DIY nav and or strobe ?


steve

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LED's?

 

LED position lights are fairly straightforward given today's tech. PC board, a few LED's, driver circuit. Low amps, long life, lite weight.

 

Anti-collision lights (strobes) in LED's are another story. The can be done, but the total amp draw will be higher than flash tubes. And a bunch more $

 

Probably wrong answer, but it adds more fuel to your question ;)

 

Rick

Rick Hall; MK-IV plans #1477; cozy.zggtr.org

Build status: 1-7, bits of 8-9, 10, 14 done! Working on engine/prop/avionics.
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I saw this debated a few years back, and someone posted the regulations regarding position lights. They were quite stringent regarding brightness, beam direction and colour.

 

It would be easy enough for someone who knows basic electronics to make lights, but you might need specialist equipment or knowledge to verify that they met the regulatory requirements.

 

Another issue that came up is that the average current draw might be lower for flashing LEDs, but the peak current draw is actually much larger for LEDs than Xenon strobes unless you do some clever stuff. A traditional strobe light works by charging up a large capacitor to hundreds of volts, which then discharges near instantaneously. An LED flasher, like for a bicycle, typically just switches the LEDs on full power for a short duration. This means that you are drawing high power for a short period of time, rather than low power all the time. As the previous poster said, strobes are more difficult than steady lights.

 

I think heating was also an issue. It's a fallacy that LEDs don't make waste-heat. They do, and for some of the new high power types, getting rid of it can be a major consideration.

 

Unless there is a get-out clause for homebuilt aircraft, which I haven't heard of, I don't think it's as simple as it might first appear.

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  • 6 months later...

Hi All,

 

Regarding the use and design of LED systems, there is a good post at this link:

 

http://www.eaa724.org/MeetingsEventsYear2004.html#anchorGarratt

 

scroll down a bit until you see the discussion about LEDs. There are some useful links regarding the lighting requirements. Quoting that article:

 

"Basically, you need 360 degree strobe coverage horizontally, plus 30 degrees of vertical visibility. The side position lights need 110 degrees of horizontal coverage, and a white tail position light must be seen from 70 degrees aft."

 

I just built a nice strobe/nav light system for my VariEze, total cost was about $70. I purchased 2 Luxeon 480-lumen LEDs (min FAA req't is 400 lumen) and made a 2-inch square flashing circuit out of about $20 in parts from Radio Shack for the strobe system. (total parts: 1 IC + 3 resistors + 1 + the 2 LEDs). I used specific values of the resistors & the capacitor to obtain an 80 milli-second flash every 0.8 seconds.. a nice 'strobe' effect... it's an easy calculation to tweak it to whatever you desire.

 

The wingtip lights required just one 75-lumen LED and 1 resistor per side, tied into the 12V bus/switch/circuit breaker.

 

My system is on the bench now, I'm currently working on the mount/installation into the plane now. I'm putting the nav lights on the canard tips, the strobes on the wing tips.

 

I'd be happy to post the entire parts list, flashing circuit, etc. if anyone is interested.

 

SPG1

Arlington, Tx

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Hi All,

 

Regarding the use and design of LED systems, there is a good post at this link:

 

http://www.eaa724.org/MeetingsEventsYear2004.html#anchorGarratt

 

scroll down a bit until you see the discussion about LEDs. There are some useful links regarding the lighting requirements. Quoting that article:

 

"Basically, you need 360 degree strobe coverage horizontally, plus 30 degrees of vertical visibility. The side position lights need 110 degrees of horizontal coverage, and a white tail position light must be seen from 70 degrees aft."

 

I just built a nice strobe/nav light system for my VariEze, total cost was about $70. I purchased 2 Luxeon 480-lumen LEDs (min FAA req't is 400 lumen) and made a 2-inch square flashing circuit out of about $20 in parts from Radio Shack for the strobe system. (total parts: 1 IC + 3 resistors + 1 + the 2 LEDs). I used specific values of the resistors & the capacitor to obtain an 80 milli-second flash every 0.8 seconds.. a nice 'strobe' effect... it's an easy calculation to tweak it to whatever you desire.

 

The wingtip lights required just one 75-lumen LED and 1 resistor per side, tied into the 12V bus/switch/circuit breaker.

 

My system is on the bench now, I'm currently working on the mount/installation into the plane now. I'm putting the nav lights on the canard tips, the strobes on the wing tips.

 

I'd be happy to post the entire parts list, flashing circuit, etc. if anyone is interested.

 

SPG1

Arlington, Tx

You Betcha!

Post your list please

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The numbers in the article are substantially correct, but there's a lot of data missing or left out.

 

400 lumens is correct, but it's effective lumens. If the LED is 'flashed' 10% of the time, you need a 4,000 lumen strobe. minimum.

 

30 degree up/down from horizontal was OK on planes certified from 1971-1977, now it's 70 degrees up/down from horizontal.

 

LED's do not emit their light isotropically, there's typically a 50% drop off at 30-45 degrees from perpendicular.

 

FAR 23.1389, FAR 91.205© (position lights); FAR 23.1397, FAR 23.1401 (anti-collision /strobe). Don't forget the difference between a strobe and/or a beacon.

 

If you're gonna be seen....

 

Rick

Rick Hall; MK-IV plans #1477; cozy.zggtr.org

Build status: 1-7, bits of 8-9, 10, 14 done! Working on engine/prop/avionics.
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Hi All -

 

Rick, thanks for the clarification on the lighting angle vs. year of manufacture, I forgot about that. And yes, there is information missing: the nav LED lights may require a reflector to cover all angles, unless a triple-branch LED like the one I'm using ("Luxen K2 Star"). I'll be sure to check it from all angles before finishing installation. If needed to cover all angles, I'll use two LEDs installed on an aluminum reflector at the proper angles. They cost just a few dollars each, and last 100,000 hours or so.

 

On the candlepower: I think a lumen is defined as the light produced by one candle shining in one square foot one foot away -- it is not a function of time, just intensity. So a 400-lumen strobe, flashing for a tenth of a second or 1 hour, is still outputting 400 lumen. LEDs come on in hundredths of a second, so they are fully bright very quickly. I'm keeping mine on for just under 1/10 of a second each second -- plenty of time to ramp up to full brightness.

 

I'll post my circuit diagram in a few days.

 

Regards,

 

SPG1

Arlington, Tx

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I've been looking at Luxeon Rebels recently. Basically one of these would work for each position light. You need 40 Candela from 0-10 degrees forward, 30 Candela 10-20 degrees, 5 Candela 20-110 degrees. Up/down illumination is a bit less stringent. Basically 30 degrees up/down.

 

The strobe light output is a Calculus problem ("Math is hard Ken" :sad: ), suffice it to say it is average illumination, not peak. If it were peak, Whelen/Grimes/Nova would be all over LED's.

 

Rick

 

ps: If you'd like my first 'trial' programmable strobe flasher to dink with, PM me an address. It's just gathering dust here.

Rick Hall; MK-IV plans #1477; cozy.zggtr.org

Build status: 1-7, bits of 8-9, 10, 14 done! Working on engine/prop/avionics.
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