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:
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)
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:
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:
The two 8 leds tubes are cooled by two water cooling circuit with independent pumps:
Two 6 feet coiled aluminium tube serve as radiator to shed heat into the air flowing around the fuse:
I glassed the nose to make-up for the carving. Quick shot of paint and voila!
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.
The project is already a success. It will start its third flying season soon, probably well over a thousand miles on it.
In this video I fly north for two miles at tree tops height, by the aid of special antennas.
In this one I make a day flight but at the end I loose the plane because I outrange the RC controls. Of course auto pilot kick-in to bring the plane back but turned into trees because I was too low.
I retrieved the plane, but a LED string was dead. Getting ready for the third flying season I rebuild the light with XM-L2, modded the driver for better/safer current handling and bumped drive current to 5A per string. The coolant system also got liquid/air separators and expansion tanks.
holy cow, I thought the original was mind blowing, but you now have expansion tanks?! Given the exquisitely done cooling system, I wonder how MT-G2 LEDs would fit and compare output wise. I can’t remember if you’re running 4S or 5S, but it looks like you’re running your LEDs as 4 parallel strings of 4 LEDs, so the 12V MT-G2 might work with your driver.
I can fit 4 Xm-L in the same foot print as one MT-G so IMHO XM-L make more sense.
I am running 4 strings of 4 LEDs on 4S lipo. Hard to say the difference with the XM-L, as I have no way to measure it, maybe we’ll see it once in the air.
The expansion tanks are 3D printed, liquid is forced into a spin and a vortex is created inside to trap air bubbles. The small air bubble contained at the top can expand/compress not to put pressure on the pumps seals.