Dave’s RV-7A Building Log

Trick-or-treating took up most of the evening, but I tinkered a little bit with the strobe wiring. I tried to figure out the best way to deal with the shields on the strobe wiring.

I got a ton of stuff done today, and not just on the plane. I washed both cars and we put the hard top back on Julie’s car. That means the garage is all mine for the winter (insert sinister laugh here). I can do the fairing on the front of the canopy, mount the landing lights in the wings, and lots of other fun stuff.

I started off working on the strobe power supply mount. I riveted it together, positioned it between baggage ribs, drilled, and pop riveted it in. CreativAir pre-drilled the mount plate to 1/4″ for AN4 holes, which isn’t so great. The holes are so close to the housing that it’s impossible to get a socket on the bolts. I ended up stepping down to AN3 bolts. I put nut plates on the back side of the mount to make it easy to remove the power supply if I ever need to.

From there I worked on getting the firewall squared away. I decided it was time to rivet in the firewall recess. I got out high-temp RTV and went to town. I managed to get the stuff everywhere. Sort of reminds me of messing with Proseal without the stink. I was able to rivet most of it solo, but requested Julie’s help for the rivets along the top and bottom. The bottom ones were really impossible to even inspect without climbing into the fuselage, which Julie thought made a funny picture.

With the recess in place, I permanently installed the cabin heat selector, contactors, battery box, and brake fluid reservoir. I dabbed RTV under the bolt heads to make a good seal. It’s cool to have so much stuff on the firewall. If you look carefully, you can see a little spec of light in one corner of the recess. It’s hard to get the RTV to span the rather large holes in the corners of the recess. It’s going to take another coat or two of RTV.

Almost forgot that I put some heat shrink on the copper bar between the contactors. I might put some electrical nipples on it as well. It seems like a good idea to cover up any metal carrying +14V straight from the battery.

I worked a bit more on the strobe power supply mount and was able to prime the parts.

Since I made the final decision on the power supply location, I was able to drill some holes and run some wire. I finally ran the first wire! I ran shielded strobe cable and the Ray Allen multi-conductor trim wire back to the tail.

I messed around with the B-nut on the cabin heat selector. I found just the right combination of washers to make a good fit.

I received my order from CreativAir that included the strobe power supply and a wig-wag flasher. It’s been like Christmas every day lately. I ordered the power supply, because I wanted to make sure it would fit under the baggage floor and it will without any problem.

I started cutting some angle to make a mount similar to the one I made for the ELT.

I also mounted the rudder pedals (hopefully) for the last time in the fuse. I had them pulled out to make working in the cockpit easier, but now seems like a good time to put them in place. I hadn’t secured any of the cotter pins on the bolts of the many swivel points, so I took care of that as well.

I finally understand how to calculate wire sizes. I’ll write up the process later. I spent a while calculating loads and wire sizes for most of the items in the plane.

I riveted the side supports to the battery box, and that’s about it.

I received my order from SteinAir including a bunch of crimping tools and some d-sub connectors and other stuff. I played around with the crimping tools a bit and read some directions on the Aeroelectric site on how to crimp on the BNC connectors.

I really just need to dive in and start wiring.

I painted some hi-temp Krylon on the battery box and associated parts. They turned out great.

I installed the handle on the top of the canopy frame. I was going to order slightly longer bolts, but couldn’t find them. Instead, I just countersunk the plastic block slightly deeper and used 10L light washers. Turned out great.

I received some parts I ordered from Aircraft Spruce including a T-handle for the parking break. It works pretty slick.

I’ve got a bunch of stuff on order including strobes from CreativAir, some wiring tools from SteinAir, and some bolts from Spruce. The parts from Spruce-West are actually taking 5 days longer to get here than the parts from Spruce-East. FedEx Ground is letting me down. Once all of that gets here I can really dive into the wiring.

Speaking of wiring, I spent an hour or so figuring out exactly how to hook up the trim system. I have wire running between a coolie hat on the pilot stick, back-up/co-pilot switches on the dash, relays, and of course the trim servos. It’s a bit confusing, but I think I have it all figured out now.

After spending the weekend in Vegas with some buds, I didn’t have much energy for the project.

An order from Van’s arrived. I try to keep a list of little things I need and then place an order once I have a half dozen things or so. This order included master/starter contactor diodes (I could get these from Radio Shack, but Van’s sells them all nicely soldered together), parking brake valve (finally broke down and decided to put in a parking brake), Ray Allen relays, some copper bus bar to connect the contactors together, and some AN3 and 4 stop nuts that are suitable for high temp use.

I fabricated the little copper strip that the plans call for between the contactors. I’m going to order some boots to cover it up. I’m a little nervous about having that much hot copper exposed.

I also fabricated the battery box hold down. I screwed up the original one, but I ordered replacement stock.

The last thing I did was prep the battery box and related parts for paint.

I cleaned up the holes in the battery box and firewall that I punched yesterday with a deburring tool, mini Scotchbrite wheel and Dremel sanding drum. Steel is not much fun to work with.

A local RV-6A builder, Dave Burton, stopped by with a 2″ Greenlee punch. He read on my site that I was having trouble cutting the holes with a hole saw, so he offered to help. The punch worked great. It’s definitely the easiest way to cut a hole in sheet metal. It would be nice to have a set of punches, but I wouldn’t get enough use out of them for the cost. Luckily, I was outbid on the punch I tried to buy on Ebay. It was for 2″ conduit, so it ended up making a hole larger than 2″. Dave said some of the punches are labeled for a conduit size and some are labeled for the cutout size. I think for the few small wiring and firewall holes I still need to make, a Unibit will work fine.

Anyway, we punched the hole in the firewall for the cabin heat very easily. After that, we finished up the lightening holes in the battery box. Well, I actually just did lightening holes on the front side. The small weight savings wasn’t worth the hassle of cutting the holes on the back. I just wanted to finish up the front so that it looked symmetrical.

Reading through some old messages from the Yahoo Group email list, I found some advice on wiring sizing. Read AC 43-13. There’s a whole chapter in there on wire sizing with tables and graphs. You can really go crazy with calculating the wire size if you want. The main point is to make the wire big enough so that 1) the wire won’t burn up before the fuse blows during a short circuit, and 2) the voltage drop in the wire is kept to a minimum. I’m still reading through the chapter, but I’ll summarize it when I get it figured out.

Also, the stick grips I ordered from Michael Lewis showed up, only a week after I ordered them! He doesn’t have a web site, but will send you information via email (michael at kalama dotcom). The grips looks awesome. You can completely customize the sticks, left-handed, right-handed, ambidextrous, any number of switches up to 5, etc. I ordered both grips ambidextrous. They don’t have the cool finger contours, but they are comfortable for either hand. The pilot’s grip has a trim coolie hat, push-to-talk button, and frequency flip-flop button. The co-pilot gets nothin’. It’s too much hassle to wire anything in the co-pilot stick since it’s removable. I’m still debating about whether I want to stick (sorry about the pun) with the ambidextrous grip for the pilot or go with a left-handed grip. The only drawback with the ambi is that the PTT button is on the top of the grip instead of under the index finger. When I fly the Cessnas, I always fly with my left hand. And I’m used to having the PTT button under my index finger. Hmmm, decisions, decisions.