Model airplane headlight, formerly "flying searchlight"

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HugeOne

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Look like my "flying searchlight" thread is gone...

Last year I built a leds light using 12 CREE XP-G leds producing each little over 500lumens. This one use 16 of the new CREE XM-L capT6. Even if very efficient, they still put out a decent amount of heat on a very small surface area. Instead of heat sinks, I built a water cooling system. The leds being so close together, a conventinal heat sink won't spread the heat fast enough, unless being very big and heavy.
I reflowed the led on 5/32" copper tubes with a flat spot to accept the led's heat pad:
tube.JPG


The tube is 3 sections soldered in a "U" shape, tube solder is lead free while leds use leaded soder. This way, the tubes don't fall apart when reflowing the leds (20C windows)
leds1.JPG


leds2.JPG


The assemblies are glued to an aluminium plate to hold them inside the aircraft and provide some air-cooling from the air rushing inside the reflector area:
leds3.JPG


As I wanted the light to spread to the side but not much verticaly, I carved a parabolic reflector in the nose of my TSII:
mouth1.jpg


The two 8 leds tubes are cooled by two water cooling circuit with independant pumps:
plumbing1.JPG


Two 6 feet coiled aluminium tube serve as radiator to shed heat into the air flowing around the fuse:
plumbing2.JPG


Details of the pumps and radiators, also the driver circuit needed to provide constant current to the leds array. Current is adjusted from 0 to 20A by a radio channel. It also start the pumps when the light is powered. Power come from a 4S lipo:
radspumpdriver.JPG


Here's a video of the light being tested on the bench:


Another one with the light installed and pumps working:



Temperature and current of the light is monitored ans diplayed on my OSD.

I glassed the nose to make-up for the carving. Quick shot of paint and voila!
side1.JPG


side2.JPG


I also made vent holes on the sides, air enter by the reflector and "nose" to come by those vents. A small ply separate the lamp area from the rest of the plane.
top.JPG
 
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^Gurthang

^Gurthang

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Huge,

That is VERY impressive work! Love the water cooling system. Could the makings of all sorts of vehicle lighting systems. You hafta post some outdoor beamshots tho...
 
H

HugeOne

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Finished!
tsii10.JPG


tsii11.JPG


tsii12.JPG


tsii13.JPG


tsii.JPG
tsii.JPG
tsii14.JPG


tsii15.JPG
 
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ma_sha1

ma_sha1

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Very cool, post some photos from the airplane camera would be awesome!

Looks like you might be able to place a small light weight Fresnel lens in front of those
leds to slightly collinmate the light a bit.
 
O

onetrickpony

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I remember when I was a kid I wanted to build a flying model of a P-38 lightning (still my favorite). Anyhoo, I got as far as one propeller. Kudos to your achieving what I never did, as well as creating a working liquid cooled multiple XML light source with a custom reflector setup catered to your exact needs.

Well done!
 
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HugeOne

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Made a quick outdoor test, light max current 13A

I looked for Fresnel lens, but did not find one with a short focal length.
 
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bbb74

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I am in awe.... :thumbsup:

Can you post when you get some movies of it in flight?!!
 
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zaskarkid

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Hey, maybe you could help your fellow plankers find they're downed planes. A local flyer used his hanger 9 twin otter to help me find my stalled 36" pylon. He simply flew over the area where he saw me go down, and rocked his wings everytime. The brush varied from 3-6ft, so it took many passes to lead us to my downed pylon. With your light and a remote s/w, you could simply flash it. Oh, but wait, this probably wouldn't work during the day. Or how bright is your light? :D

Anyways, I never would have found it without the search plane. I still fly that pylon today.
 
hellokitty[hk]

hellokitty[hk]

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:faint:
:bow::bow::bow::bow::bow::bow::bow:
 
Al Combs

Al Combs

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The original Flying Searchlight thread is still there. Only posts made in that thread after mid November would have been lost. I like the way this new plane's parabolic reflector cutout looks like a shark from the side. Would look great with a WWII P40 Flying Tigers profile.

I looked at your 16x XM-L video. What kind of runtime do you get drawing 193 watts:eek: at full power? Do you have more info about the regulator you're using? It looked like you were turning the servo's actuator disk to adjust the output.:thinking: That's got to be at least 16K lumens. That's an awesome amount of light in a model plane. Surprising it doesn't melt the Styrofoam.:)
 
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The_bad_Frag

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I like the new design very much!

Do you have a high temperature shutdown installed? If the pumps stop working the water will be boiling in a few seconds or the system has a leak and everything will go :poof: This could be expensive! :eek:
 
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HugeOne

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[Oh, but wait, this probably wouldn't work during the day. Or how bright is your light? :D
/QUOTE]

It will work... :)

I looked at your 16x XM-L video. What kind of runtime do you get drawing 193 watts:eek: at full power? Do you have more info about the regulator you're using? It looked like you were turning the servo's actuator disk to adjust the output.:thinking: That's got to be at least 16K lumens. That's an awesome amount of light in a model plane. Surprising it doesn't melt the Styrofoam.:)

Flight time holding the light at full power should be max 20min. My regulator is a home made 4ch linear unit, using a LN324 amp-op ( I can post the diagram if you need it). Signal come from the feed-back pot of a servo-motor, as I turn the servo with my remote control, I control the light's current from 0-13A. Turning the servo manualy have the same effect. The light max at about 30-35C, temp is taken on the copper tupe as close to the leds as possible. I could push the current to 20A and yield up to 20K lumens given the leds's excellent cooling, but I need more in-flight data before pushing the light.

Do you have a high temperature shutdown installed? If the pumps stop working the water will be boiling in a few seconds or the system has a leak and everything will go :poof: This could be expensive! :eek:

I have no temp shutdown installed, but temperature is diplayed on the screen. A text messgae show up and a women's voice speak "high temp" if temperature go above my 45C preset. My tests show that, at full power without pumps running, I have approx 1 min before meltdown. Probably more in flight as the shark's nose>mounth>gills provide air cooling.

-Hugo
 
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Al Combs

Al Combs

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My regulator is a home made 4ch linear unit, using a LN324 amp-op ( I can post the diagram if you need it). Signal come from the feed-back pot of a servo-motor, as I turn the servo with my remote control, I control the light's current from 0-13A. Turning the servo manualy have the same effect.
You wired directly into the servo electronics? That's pretty cool stuff.;)

I was only asking about the design of the regulator for idle curiosity. But the design of a constant current regulator as small as the one in your picture, that can handle 200 watts would generate a lot of interest. We have a few folks here that can design things like that. There are a great many more that can build it themselves if you show us how. It looks like you used a simple piece of prototype board. All it would take is a parts list, a schematic and a few photos. I guess that would be a subject for another thread though.

Nice work. Looking forward to another night time flight YouTube video.:D
 
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HugeOne

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This is what I use in the plane. The part inside the dotted line is multiplied by 4 for four strings of leds, but you can use as many as you like.
This is a linear driver so the FETs heat up, being the XM-L's Vf is close to the voltage of lithium batteries, it's not a lot of heat.

lightdriver.JPG



Here I am filling up with some car coolant anti-freeze, happened last year that my setup froze in flight, not this time.

fillup.JPG
 
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CKOD

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I'm trying to build a spotlight with 36 XM-Ls, I'm jealous that you can get away with such small radiators for 16 XM-Ls ;p though obviously flying at 20-60 mph (no idea, what it actually is, sure its somewhere in there) is why you can get away with it. :nana:
 
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onetrickpony

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I'm trying to build a spotlight with 36 XM-Ls, I'm jealous that you can get away with such small radiators for 16 XM-Ls ;p though obviously flying at 20-60 mph (no idea, what it actually is, sure its somewhere in there) is why you can get away with it. :nana:

If it's going to be mounted, you could probably borrow the idea of water cooling or use heat pipes. Check out the heat pipe page on wikipedia. It looks as though you can make them at home by putting water in the pipe and sealing the end as the vapor escapes, just before the water is gone from inside.

That or a powerful fan would go a long way. Good thing XM-L's run fairly cool.
 
Al Combs

Al Combs

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Thanks for the diagram.:thumbsup:
 

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