Dave’s RV-7A Building Log

After a 3-day weekend of camping, I’m back to building. It was good to get away for a little while and not think about the plane every waking moment. Instead I only thought about it every other moment.

As an easy task to get back into it, I installed the push tube between the control stick and the bellcrank. I almost made this impossible by installing the autopilot servo, but it was doable. At first I couldn’t figure out how to get it in without bending or cutting something. Then I checked the back-up building manual, Dan’s site. Easy as pie.

I connected the push tube to the bellcrank, but didn’t secure the other end yet so I could still move the tube out of the way for riveting the seat pan nut plates. Going to do that soon.

Speaking of getting the seat pans installed, I first needed to get the wiring done for the pilot’s control stick. I’ve spent a few hours figuring out the best way to wire up the trim servos, relays, switches, and indicators, and drawn up a wiring diagram. It’s not rocket science, but it’s definitely not straight-forward. I have a back-up switch for the elevator trim on the panel, so that complicates things a little bit as well.

I bought some cool, tiny connectors from Digikey, Molex Microfit 3.0. Turns out I needed a different crimper for the pins, and that just arrived last week. My first attempt at crimping the tiny pins worked great. I did the connectors for the relays first. No sweat. I started working on the connectors in the plane, but didn’t finish them.

The only thing preventing me from riveting down the seat floors is the wiring for the pilot’s stick. That means I needed to figure out how to wire up the trim. It’s the most complicated system on the plane because I have a hat switch on the stick connected to two relays plus a back-up elevator switch on the panel. Add to that wires to the AFS engine monitor for trim indicators. The stick also has switches for push-to-talk and control wheel steering for the auto pilot. I’m trying to get all of that wired up without a tangle of wires running everwhere. I think I can do it with two of the Ray Allen 5-conductor cables running from the panel to the stick.

I spent some time with the parts, a pencil, and some paper and got it all figured out. I was ready to start connecting wires together when I realized I don’t have the right crimper for the nifty Molex Micro-Fit 3.0 connectors I bought from Digikey a while back. I ordered the crimper and pin insert/remove tool from Digikey.

When I soldered the red position light together, I wasn’t reading far enough ahead in the instructions. Since the forward face of the cutout in the wingtips is angled back a bit, the LEDs need to be angled forward 10 degrees or so. When I soldered in the red LEDs, I didn’t leave enough of the lead above the board to bend the LEDs. I asked Bill for some replacement LEDs and he sent them out free, which was very cool.

I removed the old LEDs, sucked out the solder with a bulb, and re-soldered the LEDs in place. I still tried to screw it up by putting some of the LEDs in backwards. I really shouldn’t work on something so technical when I’m tired. I managed to get it all straightened out and the unit works great. These position lights are very cool, but it’s definitely not an easy soldering job. I’d buy the pre-made ones next time.

Now I just need to seal the board. I’m thinking of painting it with a white epoxy paint to really make it blend in.

Assembled the green LED position light and tested it. Adele held up the light in the garage while I walked across the street. Still plenty bright. I’m convinced you can see these from quite a distance.

I also assembled the mounting plates for the strobe lights. Unfortunately one screw is the wrong size, so I’ll have to order another one of those as well.

I decided to put together the LED position light kits. I swapped the band saw back to the blade I already ruined on fiberglass and cut the boards to size. I little sanding around the edges, and they fit perfect.

I next did a bunch of installing of tiny parts and soldering. Unfortunately, I didn’t read far enough ahead in the instructions and installed some of the LEDs too close to the board (and trimmed the leads) in order to get the necessary angle on them. I’ll have to order some extra LEDs and replace the ones I have. I hate making dumb mistakes, but I was able to test the red light. Works great. I can confirm that they are bright and you’ll see spots after staring into them. I’ll leave the green one for later.