Ethan's RV-7

2.0 Hours -

I think I can finally say that my homemade wingtip lights are finished!

This morning, I took an hour to finish drilling all the remaining holes in the aluminum back plates.  On the left side, I only had to drill four holes for mounting the heat sink with pop-rivets and two holes for mounting the strobe tube with #6 screws.  On the right side, I had to drill these holes along with a 1/4″ hole for the grommet that the power leads will pass through.  The holes for the strobe tubes didn’t turn out as straight as I would have liked (vertically aligned with the wingtip), but they will pass.  The holes for the heat sinks were a bit trickier to drill since I had to be careful not to drill where any of the LEDs had been placed.

Once everything was drilled, I went back inside to finish wiring the right side LEDs.  Soldering only took a few minutes since all I had left was the two power leads.  As soon as the leads were attached, I connected them to my bench power supply and a Buckpuck.  Since I didn’t have to hold wires in place, I was able to take a picture with the LEDs on.  The camera sensor really struggles to take pictures of these.  They are bright!

After soldering the power leads, I fired up the cyan LEDs with the Buckpuck.

The aluminum back plate and mirrored plexi had to have two holes drilled for mounting the strobe tubes. The black heat sink will be riveted to the back plate behind the LEDs.

After taking a lunch break, I started final assembly of the wingtip inserts.  The first thing I did was to clean the back of the insert and attach the heat sinks.  Before riveting the heat sinks to the aluminum, I coated the back of the heat sink with some Arctic Silver thermal compound to aid heat transfer from the LEDs to the aluminum back plate and finally to the heat sink (this is the same thermal paste that is used on computer processors to conduct heat to the heat sink/fan).  Once the thermal compound was applied, I pop-riveted the heat sink to the aluminum plate using 4 rivets.

The heat sink is attached with pop-rivets after applying some Arctic Silver thermal compound.

A side view of the heat sink to give a better idea of its size.

With the heat sinks in place, I decided to do another bench test of the LEDs.  I ran each side for 20 minutes.  During this time, I regularly checked how hot the assembly was becoming.  On previous tests, without the heat sinks, the aluminum plate would be too hot to touch after only a couple of minutes.  With the heat sinks, I could still hold my finger on the aluminum after 20 minutes.  The aluminum was warm, but by no means hot.  The heat sink, however, was hot.  I guess that means it is doing its job!

Having a successful heat transfer test in the bag, I completely assembled both wingtip inserts.  I used two #6 screws and nuts to attach the strobe tubes and strobe-side mirrored plexi.  I also used three #6 screws and spacers made from stacks of rivet washers to attach the LED-side mirrored plexi.  The only down side is that I’m still leaving the protective paper on the mirrored plexi, and I probably won’t remove it until the wingtip lenses are complete.

The wingtip inserts are now fully assembled, and they look good!

A side view of the completed insert.

A close-up view of one of the strobe tubes. These things are works of art!

Next, I decided to pull out my new strobe power supply and test it.  I hooked it up to bench power and connected two strobe tubes.  The strobe power supply has 15 flash patterns to choose from and I ended up using the alternating triple-flash pattern.  The single and double flashes seem to be too fast, while the quad and quintuple flash patterns just seemed like way to much light!  I’m sure I’ll play with this more later on down the road.

My Strobes N More Pro Series 606 strobe power supply. After testing the 15 flash patterns, I decided the alternating triple flash would be best.

Finally, I received my LED filter/driver assemblies from Aeroelectric.com.   I bought one assembly for each wingtip.  Since I already had one Buckpuck driver on hand, I bought one filter with the driver already attached and one the was the filter only.  In order to attach my Buckpuck to the filter board, I glued it in place with some E6000 and then I had to solder the pins.  This is the first time that I soldered a component to a PC board, so I wasn’t sure how hard it would be…the pins are close together and the solder joints can’t touch each other.  If they touch, they short!

Well, in the end, this turned out to be the easiest soldering I’ve done.  Compared to the LEDs, the small solder pads on the board were easier to heat up and the solder wicked in more cleanly.  Personally, I don’t see much difference between the board I assembled and the one the came already complete!

A bottom view of the LED driver/filter assemblies. I soldered the bottom six pins on the assembly on the left, while the one on the right was completed by the seller.

The top side of the filter/driver assemblies. I need to find some 4-40 screws and lock washer for mounting these on the outboard wing ribs.