Dave’s RV-7A Building Log

The cowl support is a real PITA. I think it’s easier for the upward draft cowls. On the horizontal draft cowls, the support is angled up so much, there’s no room to drill the holes into the gusset. I drilled the holes in the gusset to #40, put the support in place and marked as best I could. I drilled the support to #40. From there I test fit, drilled to #30 adjusting the location of the hole slightly to help things line up better, and then repeat for #19 and #10. I had to do just a tiny bit of elongating the final sized hole and the bolts fit perfectly.

That wasn’t even the real pain. It took one hour to get the two bolts in place with the nuts on, and that was only after Julie helped me. Access is poor, to say the least. This picture shows the final result including riveting the two parts together, trimming the aft end a bit, and installing the bolts. I used all-metal stop nuts instead of the nylocs called out in the plans. This is right next to the exhaust pipes. Nylocs would roast. I’m never taking this thing off again. Ever. Cross it off the list.

Decided to next work on the forward deck hatches. I cut the holes in the skin using a Unibit, die grinder cut-off wheel, and a Vixen file. I then cut down the fiberglass panels I’ve been fabricating during the week. This picture shows how it will look when I epoxy the two parts together for each hatch.

Make sense now? I may need to increase the thickness of the flange fiberglass. Then I drill, dimple the skin, countersink the fiberglass flange, and install nut plates.

Long, productive weekend, even though I didn’t get a lot crossed off the list. I just gotta realize that some of these final tasks are going to be time consuming.

I drilled and attached nut plates to both sides for the cowl hinge pins and countersunk where necessary. The covers for the cowl hinge pins are officially done. I’ll probably use tinnerman washers under these screws.

I also did a little work for the forward deck hatch covers. I popped off the covers I made previously. I started with 5 more layers on each mold for the cover flanges.

I spent most of my time making the cowl support that goes behind the nosewheel leg. Nothing’s pre-punched, so there’s measuring plus the usual drilling, countersinking, nut plates, etc. I also made the bend at the front where it attachs to the engine mount gusset. I remember Walter Tondu had done something different, but didn’t look at his site early enough to copy his idea. He used a couple of adle clamps to hold it to the mount rather than drilling through the gusset. Good idea.

Following the dimensions on Dan’s site, I made the cutouts in the oil door for the flush Hartwell latches. After drilling #30 holes in each corner, I tried using a cut-off disk in the Dremel. It didn’t work very well–the disk broke. I resorted to using a bit that looks very similar to the one Dan used. I think it’s a laminate bit. I cleaned up the cut-outs with some files. Turned out great. Now the only problem is the latches. I think there are two varieties of H5000-2 Hartwell latches out there. One sticks up quite a ways and works well for fiberglass. The ones I have only stick up .025″ which would be better for a metal door. I’m going to see if I can find the other variety at the Arlington fly-in next month. (You can see in the picture that I nicked the oil door slightly with the Dremel bit. I’ll just fill that in.)

I worked on shaping the filler from yesterday around the seam behind the spinner. The microfiber filler is really hard to sand down, but I got it looking pretty good. It just took much longer than I would have liked. I installed nutplates for the screws that hold the front together.

Marked the lines on the front deck onto the fiberglass and popped it off, no problem. Looks great.

I next drilled two holes in each cowl hinge pin cover and popped them off the saran wrap, no problem. The covers looks great. I figured out where I wanted the hole and drilled it to 3/4″ with a Unibit. I put a little bend in the end of the hinge pins and cut them to size. I have to rotate them to get them out, but that works fine. I cut and sanded the covers down to about 2″ around. I’ll get some #6 corner nut plates from Spruce and use flush screws. After I took the pictures below, I sanded down the covers some more so that they’re nice and round and the edges are rounded.

I made a little test swatch of fiberglass yesterday 3 layers thick. Measuring it today, it’s about .036 thick, so about .012 per layer. I’m using the 8.8oz bidirectional Rutan cloth from Spruce.

I did some measuring to figure out wiring lengths for the avionics so that John Stark can make up the avionics harness.

The last thing I did for the day was mix up some epoxy with microfiber filler to fill some gaps between the cowl halves. I applied some to the lower cowl where it meets the upper cowl around the prop. I put some saran wrap over it and put the top cowl in place.

I feel like I’ve been doing nothing but custom items lately, but all of these things will be well worth the time and effort.

Today I laid up more fiberglass than I’ve ever done before in one day. I put down 3 layers of 8″x8″ fiberglass on the front deck. I later put on 2 more layers with some cardboard sandwiched in there to add stability. I’ll actually use these as molds for the access covers so that they have a smooth top surface. I stole this idea from my friend Jim Piavis.

I put down 5 layers of 2.5″ x 3.5″ over the cowl hinge pin access areas and laid some dacron on top. That stuff is great for making a smooth surface, I pulled it off after a few hours. The epoxy was really setting up fast, so I had to work quickly. Once I was done, I wheeled the cowl (I had it on my creeper) out into the sun. That really accelerated the process.

I also worked some more on the cover for the cabin frame support and painted, and touched up the support itself, and painted a couple of door handles for the house for Julie.

I pulled out the lower cowl support parts and for some reason decided the dimensions I laid out yesterday were wrong. To my credit, the plans are confusing. Well, I changed the dimensions and drilled them all wrong. I could do some creative epoxy filling, but I think I’ll just order new parts for $15 and move on.

I was too tired to do much tonight. I mainly just prepped for laying some fiberglass tomorrow. I laid out some lines for the 5″ square hatches on the front deck and waxed the surface. I also decided and marked where I wanted the holes for accessing the cowl hinge pins and then covered the area with Glad wrap. The last thing I did was marked the holes for putting together the lower cowl support that’s needed for the -A nosegear models.

Cleaned up the excess epoxy on the outside of the top cowl and tried it on for size. Looks very cool without clecos. I can’t install the camlocs along the top until I rivet down the forward top skin.

I only had a little bit of time before/after Adele’s piano recital. I messed with making a cover for the support between the cabin frame and baggage compartment wall. I also pulled out the parts that support the cowl behind the nosegear leg and marked them for drilling holes.

Adele’s last soccer game of the season was last night, followed by a little party. No time for building.

I installed the bottom cowl to check the fit. Looks great without clecos. I secured the bottom camlocs. They’re adjustable, so I twisted them in a bit to make them flush with the cowl.

On to the top cowl. I roughed up the cowl and hinges with some 100 grit sandpaper and cleaned them off. A little epoxy, a little riveting, and it’s a done deal. I think it was even a little warmer tonight, as the epoxy seemed to set up really quickly.

On the avionics front, I finalized the equipment list and mailed a check off to John Stark. Here’s the list:
Garmin GNS-430 GPS
Garmin GTX-327 transponder
Garmin SL-40 comm
PS Engineering PMA-8000b audio panel
Trutrak Digiflight II autopilot

I’m also having John do the wiring harness to save myself the time, headache, and potential of ruining some expensive equipment. I’m only getting the tray for the GNS-430 at this point. There’s a rumor that the WAAS version of that unit will be available soon. I’m guessing it will be announced for Oshkosh. I’m going to wait to see what the price ends up being. I’d like to have WAAS.

Mixed up some epoxy and microfibers, spread it on the hinges, and riveted them to the bottom cowl. I used a bit too much goo on the first hinge and had to spend a bunch of time cleaning up the excess with a toothpick. I wanted to make sure the epoxy wasn’t getting into the eyelets or would interfere with the other half of the hinge. Two batches worked out perfectly for the four hinges. The stuff definitely cures much faster when it’s 70 degrees out versus 60.