Dave’s RV-7A Building Log

I started the process of trimming the baffles to the top cowl. The trick with the 1″ aluminum circle and a cut-off sharpie works excellent. I put the side and rear baffles (and later the front floors) onto the engine. I placed the top cowl on top and made sure it was centered. There was about an inch gap in the back and front.

This picture shows how the aluminum circle is used. Ideally, the disk should be flat against the baffle.

Reaching in and around the engine, I was able to use the circle to mark a trim line all the way around. On the left side of the engine, it seems to be easier to mark the inboard side of the baffles. The right side is the opposite. I guess it’s the way the engine is positioned relative to the cowl.

I used tin snips to make a rough cut at the trim line. I was able to accomplish this without removing the baffles for the most part. Lather, rinse, repeat.

It took about 3 rounds of that before the cowl was sitting down into its normal position. The baffles were nearly perfectly trimmed right up to the cowl.

I then marked the final trim line all the way around the baffles. The 1″ circle makes the line 1/2″ below the cowl. The instructions say this is the maximum amount, but I’ve heard from other builders that 3/8″ can be a bit too small. They’ve seen the baffles rubbing on the cowl. I don’t want that.

I’m going to think about the final trim a bit more and do the trimming probably on the band saw tomorrow.

I really thought that trimming the baffles to the cowl was going to be a major ordeal. So far, it’s turned out to be fairly easy. All I have left on the baffles is the final trimming, mounting the oil cooler, installing the oil cooler stiffeners, riveting all the parts together, painting, and installing the seal fabric. Well, I guess I still have a ways to go.

I didn’t have much time to work on the plane. The furnace has been acting up. I had to spend an hour tinkering with it. The problem ended up being a clogged up orifice in the pilot light line.

I made a 1″ diameter washer out of aluminum with a tiny hole in the middle. I read a trick on the Matronics list that involved this washer and a Sharpie in order to mark the baffles for trimming to the cowl. It sounded so cool that I had to try it. I’ll see how it works tomorrow.

I put both halves of the cowl on and clamped a block to the crankcase flange that will hold up the top cowl at just the right height. I want to be able to install and remove just the top cowl during the trimming.

The alternator air door flange set up well overnight. I’m using the “fast” hardener, and it’s still taking a while to set up. I moved the part inside to keep it warm, which I think helped. I drilled out the holes again that got filled up with epoxy and used a deburring tool to clean up the dimples.

Overnight I thought about how to attach the pop rivets. In other locations where pop rivets are used in fiberglass, they are backed up with a washer. In this location, you don’t want any chance of the washer getting loose and falling into the air intake of the engine. I hate to think of what a washer would do to the inside of the engine. I had some left over #4 washers I ordered a while back, which is the perfect size for 1/8″ pop rivets. I decided to use the washers, but epoxy them in place. I used some JB Weld under the washers, pulled the pop rivets, and then added a little more JB Weld over the top and around the edges. The washers aren’t going anywhere and the pop rivets won’t pull through the epoxy. (Sorry for the fuzzy pics.)

I then attached the door and gave it a try. Works excellent. This is something that will stay closed 99.9% of the time. The only time it gets opened is if the air filter gets clogged up for some reason.

After lunch, it warmed up enough to do a priming session. It’s been a long time since I’ve done any priming. I actually like it, because I know the next step is final assembly!

I was hoping this weekend to get the baffles to the point of trimming them to the cowl. I got pretty close. I feel anyway that I’m over the major hump with these crazy baffles. I spent a ton of time going part by part, doing any last trimming and drilling. A few things have to wait until after the baffles are trimmed to the cowls, like the oil cooler.

This appears to be a common problem. With everything screwed down, this one flange just wasn’t sitting right. Cranking it down would have tweaked everything around it to the point of not fitting.

I ended up cutting off the flange and using a short chunk of .063 x 3/4 x 3/4 angle. I also made the stiffener for the back right side wall from the same angle stock.

I bent the back bulkhead bracket some more. It was about 3/8″ short of where it needed to be. I then drilled the back bulkheads to it.

I also drilled the two back left bulkheads to each other and did some final filing around the engine.

I have a bunch of riveting to do now, but the baffles are basically ready for trimming to the cowl after a lot of hours on them this weekend. Yeah!!

I’ve done a ton of thinking about it and decided I’m finally ready to have the panel cut. I’m sure I’ll find something I forgot, but I can always cut it myself later. I sent the file to Ross at Experimental Air to lay out and cut. I’m also going to get his air vents, as they look like the best out there.

I riveted the nut plate onto the flange and enlarged the hole in the FAB for it. I mixed up some epoxy with flox to fill under the flange. I mixed it up to the consistency of paste per the instructions. I clecoed the flange in place and noticed it wasn’t sitting very level with respect to the FAB. I used a side cleco clamp and a small block of wood at the nut plate end of the flange. Then I noticed that the flange appeared to be bowed. The best approach is to just clamp the flange in two maybe three spots so that it’s sitting flat and square to the FAB.

I also did some trimming on the baffle floors. I think it’s the FAB instructions that say to bend down the forward lip of the baffle floor. Seems like a good idea. The flange will provide more rigidity to the middle of the floor.

I also cleaned a batch of baffle and alternator parts for priming. The weather is supposed to be good tomorrow.

Sorry for the lack of pictures lately. I’ve just been in a zone of getting these baffles hammered out. I won’t be done a day too soon with these miserable things.

I worked some more on the alternate air door. I finished off the hole in the FAB pretty easily. I positioned the flange, drilled the holes, dimpled the flange, and countersunk the fiberglass. The fiberglass was a bit thin on one side. It wouldn’t hold a cleco after being countersunk. I’ll have to do something about that. I also bent over the little tab at the top. It forms a slot to hold the door. One end of the slot is crimped to form a stop. I was skeptical, but I tried rotating the door into the slot and it seem like it’ll work pretty good.

The P-mags finally arrived. They look great. I ordered auto spark plugs with the adapter rings. I also ordered a kit for making the spark plug wires. It included a crimper, which is cool.

The leather samples for the seats also arrived. There are a couple of colors that look good. I’ll wait until the harnesses get here to make the final selection.

I pulled out the drive gears that I got from Mattituck and started installing those on the P-mags. I’m going to need a strap wrench in order to get them tight enough. I also just mucked around with the P-mags for a while, figuring everything out. In order to install them, I need to move the crank to TDC #1. I asked Mahlon if I can do that now or or wait til later. He said it’s better to wait. I think moving the crank will disturb the preservative oil that they sprayed in there. I’ll install the P-mags, but won’t time them until I’m ready to fire up the engine.

I did a tiny bit of work on the FAB. I located and started cutting the hole for the air bypass. Cutting that hole is not very easy without a 2-5/8″ hole saw. I tried using the fly cutter, but it didn’t work very well. It at least scribed a line that I cut to with the dremel. I still need to file it to final size.

I continued with the filtered airbox installation. I drilled the left filter retainer to the left baffle side wall and drilled everything else how to full size. I disassembled everything for deburring and dimpling. I installed nut plates on the FAB flanges. I marked the left baffle side wall along the bottom for trimming to the floor, cut it, and cleaned it up.

The next step in the instructions is to install the filter bypass, so I pulled out the parts for that. Looks pretty simple. Actually the next step is to rivet some parts together, but I’m sort of holding off on that. I like to rivet things as late as possible in case any issues come up. Plus I want to prime some of the parts. Eventhough they’re alclad, they’ve gotten really scratched up in the process of being fitted. It looks like we might have some good priming weather this weekend.

I finished up filing the cutout in the left baffle floor so the filter would just slip into the opening. That took quite a while.

I then assembled everything again and drilled the left and right filter retainers. The left one is extra large, so I marked and cut it down to size. I also laid out some holes that will attach it to the left baffle side. The retainer takes the place of the angle that normally attaches the left side baffle to the left floor.

I saw on the VAF web site that Classic Aero is getting backed up with seat orders. The lead time has stretched to summer. That means it’s time to place an order. I called them up and ordered some samples of the leather seat material. They have two models of seat. The more expensive one of course sounds much better. They’re even making some slight modifications to the seat in response to requests from customers. They sound like a really good company to work with.