Dave’s RV-7A Building Log

I determined the final location of the front bulkheads and drilled the brackets to the floors. I used some blocks of wood to make sure the bulkheads were parallel to the ring gear. I was able to drill the brackets on the diagonals pretty easily.

I marked the locations of the brackets and then carefully removed the ring gear for better drilling access.

I still need to tweak the height of the bulkheads and the fit to the floors a bit more. I also trimmed the bracket that holds the bulkheads to the front of the engine case. The bracket turned out pretty good.

This month ended up being the lowest number of hours I’ve spent on the project in quite some time. A week of skiing will do that. It’s also not as fun working out in the garage when it’s cold.

Worked on fitting the front bulkheads. It’s not clear where they should be located. There are notes on the diagram that they need to be at least 1/2″ from the start ring gear and that they should be parallel to the gear. I located them as far back as possible to provide enough room for the brackets that attach the bulkheads to the floors.

I wasn’t sure how to locate them relative to the cowl inlets, but there really isn’t much choice. They should be inboard of the cowl inlet and yet 1/2″ from the starter ring gear. Mine will end up lining up with the inboard edge of the inlet. I trimmed a tiny bit off one side to provide clearance to the inlet.

With the rough location determined, I made the brackets pretty much as they are laid out in the plans. A couple of them were a little bit shorter. I made them from the .032 angle provided in the baffle kit. I wasn’t sure whether that angle was for the brackets or the right wall stiffener. The other choice was to make them from the .040 sheet, but that would have been pretty hard to bend.

I haven’t been able to find many pictures of the baffles on other builder sites. I can see why, as the baffles are just tedious and confusing. I haven’t been taking many pictures either. I’ll be glad when the baffles and cowl are done.

Today I’m offically an airplane builder. After nearly 2.5 years of working on the plane nearly every day, I finally drilled a hole in my finger. It’s certainly a dubious milestone in the project.

I finally had the energy today for some serious work on the baffles. I tweaked the support for the right front floor and shaped the tab to cover the prop govenor oil line slot. I suppose if one cut the slot just right, the tab wouldn’t be necessary. Here are two views from below and one from above.

One thing I just don’t get about the baffles is how the sides are supposed to seal against the sides of the cowl inlet. Even if I pull the sides in tight, it seems like there’s still going to be a big hole there. I’d especially like to keep the left floor as wide as possible for the engine intake filter.

I cut up some thick paper to simulate the seal material. Along the sides, the material pushes against the cowl. Along the cowl inlet bottom, the seal kind of bridges the gap from the cowl to the baffle floor. I guess the two overlap enough to make a decent seal. The instructions say to center the sides in the “slot” of the cowl. I guess this is what they are talking about.

I shaped the angles that attach the right floor to the right side baffle and drilled them in place. The drawings and instructions are a bit contradictory on how to deal with the aft part of the junction. I just kind of faked it as best I could. It all feels solid. The aft-most side rivet goes through the bolt reinforcement. The drawings kind of indicate using one of the existing holes in the reinforcement, but I couldn’t make that work. I just drilled a new hole.

I also riveted together the bracket and tab contraption and added some nut plates for #8 screws. It also feels quite solid. I figured out which rubber grommet I need from Spruce to seal the gap around the oil line.

I pulled out the front bulkheads and spent a little time trying to figure them out, but I’m done for the day.

Spent more time on the right front baffle floor fit. I made a little tab to secure the slot of the prop governor line.

We’re back from skiing/boarding at Mt. Bachelor. Great place. We had great weather, great snow, and the view from the mountain was incredible.

I spent a little time just getting back into the swing of things. I messed around with the right front baffle floor.

I finished up installing the Vans 60 amp alternator. I still need to disassembly and prime the extruded/milled aluminum parts, but everything is fitting really well. The hardest part was bending the 1/4″ strut that connects the alternator and starter. It needed a slight jog. I put it in the vise and hammered on it with a dead blow hammer until it was just right. I also had to do some more fine tuning of the mount bracket and the ears on the alternator. There was a fair amount of interference at first. The instructions say that the arm that holds the outboard side of the alternator might need a jog as well, but mine worked right out of the box.

I checked the clearance to the FAB air intake and it’s much better with the smaller alternator. The whole alternator can swing up much further before hitting the prop oil line.

I noticed one very interesting thing as I was messing withe the FAB (filtered air box). I seem to have enough room on the baffle floor to install it. I think most builders trim the outboard edge of the floor, unaware that it will cause problems fitting the FAB later on. On the advice of a couple other builders, I kept my floor full width. I’ll have to mess with it some more to be sure, but I’d be very happy if it fits without major surgery. Most builders end up modifying the FAB by cutting a chunk out of the middle, or altering the baffles.

I didn’t spend too much time on the plane, but Julie was nice enough to allow me an hour with the mistress on Valentine’s Day.

Mattituck installed an alternator on my engine by mistake. They were nice enough to let me keep it if I could use it. Well, I can’t use it. It’s much larger than Vans 60 amp alternator and is interfering with the FAB intake to the fuel servo. I could modify the servo, but I’d rather just swap out the alternator.

I pulled out the parts and instructions for mounting the Vans alternator. The Mattituck alternator was apparently in an aircraft-style housing, so it fit the standard mounting bracket. The Vans alternator is straight off a car, and so needs a different mounting bracket. The bracket that Vans includes in the kit is made from aluminum rather than steel, but looks beefier. It also attachs at 4 spots rather than just 2. I had to file a bushing on the alternator (as mentioned in the instructions) in order for the bracket to fit properly. There’s also a strut that ties the starter to the alternator. I don’t know that it’s required, but it couldn’t hurt. I started fabricating that out of aluminum bar stock also provided in the kit.

I received a letter from Vans confirming my propeller order from Hartzell. They’re going to ship direct. The expected ship date is May 10, 2006!! I know they said to expect a 12 week lead time, but holy cow. I hope it gets here before that. I’d like to confirm the fit of the cowl before then. Assuming shipping takes a week or two, I might not see it until the end of May.

This just confirms that I need to order the rest of what I need for the plane. I was trying to pace out the purchases and buy things only as I need them. But I don’t want manufacturing delays to hold up my project. I’m going to confirm my avionics choices at the aviation trade show in Puyallup next Saturday, and then it’s time to do some major ordering.

I worked a bit more on the parts that attach the FAB to the baffle floor. The drawings are not very accurate. The side parts need to be much shorter than what is called out. Also, the corners don’t fit together very well unless you cut an extra jog in the flange. I’m having a little trouble figuring out how this whole thing is supposed to be sealed. At least I think the idea is to have a pretty good seal between FAB, the filter and the baffle floor.

The main point of figuring out the parts was to help determine the location of the filter on the floor. It looks like I can position the filter so that the aft edge of the filter frame is right at the bend line.

I worked further on fitting the forward left baffle floor to the cowl inlet. I had to trim quite a bit more off the inboard edge of the floor so that it could slope down to the cowl inlet and not hit the crankcase. That involved several iterations of installing/removing the bottom cowl (not an easy task solo) and installing/removing the floor and grinding it down with the Scotchbrite wheel. I eventually got the forward floor edge to line up nicely with the cowl inlet. I then worked on the bracket that holds the inboard edge of the floor in position. The part comes flat with a large bolt hole in it. Not helpful. It would be much better to have the bend but no hole. Putting a bend in a small piece of .063 sheet exactly where you want without a bending brake is not fun. I used the vise, the hand seamer, a board, a hammer, and some colorful language. Surprisingly, it turned out pretty good.

The FAB instructions say not to install the angle the connects the left floor with the side baffle. The FAB kit replaces it with a different piece. I guess I move on to the right floor now.

I didn’t do anything on the project over the past two days. Took a little break for some computer projects. Today, I worked more on the front left baffle floor. I positioned and drilled the 2R stiffener angle at the front of the cylinder and part 14 that holds up the right side of the floor. I had to do a lot of trimming in the process, but it’s starting to fit pretty good.

I test fit the cowl and it’s obvious that the cowl inlet needs to be trimmed back in order to make enough room for the air filter.

I trimmed the cowl and re-installed it.

I took a few iterations of trimming back the left side baffle before the fit was looking good. I need to study a bit more how the filter and FAB gets attached to the baffle floor before I can figure out if I need to trim the cowl more or not. I’m not sure if the edge of the filter can go right up against the bend just forward of part 2R. If it can, I have about 1/4″ between the cowl and filter right now. That looks pretty good.

After dinner I went back out and started making the parts that connect the FAB to the bottom of the left baffle floor. Getting these figured out will help me determine how to position the filter.