I fit and drilled the lower portion of the rear baggage wall. The top portion needs a radius cut in it. After measuring for the center, I taped one of my sharpie pens to an old compass and adjusted it to 8.5″ and marked the cut. I then used some tin snips and a vixen file to trim to the line.
We were busy most of the day at a cub scout event with my son, but I managed to put a couple of hours in this evening. I got started by fluting all of the bulkheads and making sure their flanges would lie flush with the skins. I then temporarily attached the rear top skin to mark a few holes that are not predrilled.
The bottom three holes on F-709 on each side are not drilled. I marked their position through the holes on the skin so that I can determine where to flute. You can see that this area will need some significant fluting.
I then trimmed and fit the stiffeners and then put on the forward skin. One final rib is inserted on the top skin between F-706 and F-707 as well as a gusset plate (where the numbers 479 are visible).
Finally, I match drilled the skins to the bulkheads and stiffeners.
Now that the skins were in place, I needed to drill the bulkhead gussets to the longerons. Instead of peeling back the skins, I just climbed back into the tailcone and drilled the gussets in place. For the F-706 bulkhead, I clamped a straightedge across the opening to ensure the gussets hold the two sides of the bulkhead perfectly in line with each other.
Finally, I clecoed the baggage floor back in place.
…and then clecoed and clamped the lower back wall of the baggage compartment in place.
I got started tonight by fabricating the spacers that sit under the aft deck. Here is the one that sits on top of F-710.
Now that all of the rivets along the longerons are set, the F-711D angle could be riveted to the F-711 bulkhead. I managed to get a squeezer on these.
I positioned and drilled/reamed the seatbelt anchors just in front of F-708. I also reamed the 1/4″ holes in the front for the bolts that attach the cable.
After drilling the F-728 angle to F-706, I riveted the reinforcing angle in place. I was able to squeeze one of the rivets that attach F-728 to F-706 at the top.
I was also able to squeeze the upper four rivets that attach the lower end.
I finished the left F-757 plate and drilled it to the F-705 channel and longeron.
There were two holes in the aft fuselage that I couldn’t dimple earlier because I inadvertently riveted too far up F-711. The vertical bars prevent getting a squeezer aligned with these holes, so I needed to get creative. Since the longeron is already dimpled and thick enough not to flex, I could just use the male portion of the die to form the dimple. Since the vertical bars prevent clamping directly, I used a scrap piece of angle and some clamps to either side to drive the male dimple die flush with the skin. This worked perfectly, and a rivet sits completely flush in the hole.
I managed to squeeze all of the remaining holes with the exception of the upper two holes in the forward flange of F-711. I’ll have to shoot these, but it’s too late to run the rivet gun tonight.
I started tonight by laying out the hole in F-757 for the tip-up latch mechanism.
After drilling and filing for about 15 minutes, I had a nice square hole with radiused corners. I fit it along with aft canopy deck and match drilled it to the F-705 channel.
After clamping it in place, I then match drilled it to the longeron and laid out and drilled three additional holes in the aft end. I started working on the left side, but it was making too much noise and keeping our son awake.
I went ahead and torqued down the #10 screws in the tank attach brackets.
I also fit and match drilled the F-709 bulkhead.
Finally, I fit the F-695 gussets that tie the upper longerons and engine mount to the firewall stiffener. The forward edge of these needs to be filed to be parallel with the firewall when the outside edge is flush with the apex of the longeron. The forward edge also needs a little bend up to lay flat against the stiffener.
After determining where the aft end of the engine mount is, I laid out 10 holes forward of this point and four holes after. This resulted in slightly different spacing than called for in the plans. I had basically 1/2″ between the forward 10 holes, but only 13/32″ between the aft four. This ensured adequate edge distance all around. I also laid out for 5 holes along the front edge. I then drilled these out to #40.
I then clamped the two gussets together and transferred the holes to the other one.
After clamping the gussets securely in place, I match drilled the longerons, engine mounts, and firewall stiffeners to #40 and then enlarged the holes to #30.
Here are the completed gussets. I’m going to wait to prime and install these until I have a sufficiently large pile of parts to prime.
Andre stopped by today to help me finish up the riveting on the forward fuselage. We didn’t get any pictures during the process, but here is the finished result. The holes along the firewall will wait until they’re match drilled to the hinges that are used to attach the cowling.
Some of the holes where the fuel tank brackets attach can’t be reached with any of my regular bucking bars, so I taped a hunk of steel to one of my long rivet sets and used the rightmost end to buck the rivets.
Jenn came out and helped Andre and I flip the fuselage.
Jenn took a shot of me checking out the pilot’s seat.
Andre and I checkout out how roomy the cockpit is.
Here you can see that I’m using two low saw horses under the front part of the fuselage so that it is nice and stable when climbing in and out.
After Andre took off, I installed the AN3 bolts through the lower engine mounts and lower longerons. I probably should have done this before riveting on the bottom skin since I couldn’t get a torque wrench on these. I had to calibrate my hand and do these by feel.
Afterward, I leveled the fuselage front to back. Here is the reading along the longerons between F-704 and F-705.
I also leveled the fuselage side to side at several points along the fuselage to ensure there was no twist. Here is the reading at F-705.
And at F-704.
And at F-710. I doubled checked all of the readings with a bubble level and them clamped the aft deck in place.
I needed a ratchet clamp to apply a little side load on the aft vertical bars to remove all of the twist. After I tripled checked everything was straight, I drilled the aft deck to the longerons.
Goddamnit! I got my foot caught up in the air hose, pulling my drill and box of rivets to the floor. After swearing a blue streak for a few minutes, I started trying to sort them and then realized it was going to take several hours. This is probably only about $10 worth of rivets, so it’s just not worth my time.
I started to seal up the firewall last night, but after reading about the mixing ratio (40:1), I realized my digital scale wasn’t nearly accurate enough (it was only accurate to 1g). Tonight after work, I swung by Fry’s and picked up this digital scale that is accurate to .1g.
The A part of this mixture is basically like tar. You’re basically cutting chunks of it out of the can. The B part is a liquid. When mixed together, it forms a thick paste that will cure to a flexible state and withstand 400ºF sustained and handle flash temperatures to 2000ºF.
Initially, I started mixing this up in a paper cup, but as you can see, the B part immediately started soaking into the cup. Rather than guess how much additional B part to add, I tossed this batch and mixed up another one in a plastic cup. Since I bought a 1/2pt kit, I probably have enough to do two complete firewalls, so this is no big deal. I’ll still have plenty left for the other parts of the firewall that will need sealing.
Here you can see where I’ve applied the sealant to the firewall flange. Basically, you just butter on a thin, even coat and then cleco the parts together.
To ensure a good bond, I put a cleco in every hole around the firewall (including the double row along the bottom skin. I also clecoed in the final two bottom skin stiffeners. This thing is ready to rivet together. Andre is planning on stopping by on Sunday. With any luck, we can finish this up and flip the fuselage.
The hole right below where the forward fuel tank attach bracket needs to be drilled and countersunk for a #10 screw. I drilled this out to 3/16″ and then used the #10 countersink cutter to countersink through the sandwich of the side skin, bottom skin, and lower longeron.
Here you can see that the screw will sit perfectly flush after install.
I removed all of the forward clecos and pried the side and bottom skins away from the firewall in preparation for applying the sealant. I also scuffed all of the mating surfaces. The mixing ratio is too precise for me to use the scale I have (only accurate to 1g), so I’m going to need to track down a more accurate scale before I can mix the sealant.
I used a couple of these stubby #40 clecos to keep the side skins spaced away from the firewall.
I also installed the AN3-10A bolts through the rear spar and spacer blocks. Getting these spacer blocks in was more of a pain than I would have expected. It was also tough to get a torque wrench on the nuts on the other side. I ended up having to use a crow-foot wrench on the end of my torque wrench to get them.