Undercarriage Channel

Fresh back from a week of vacation on Cape Cod, I resumed work on the center fuselage. On Sunday I worked on page E3, which assembles the rear bottom assembly, undercarriage channel, and main spar assembly onto the bottom skins. Quite a few big and substantial assemblies here, but that’s because most of the weight of the aircraft is supported in this area.

Riveting together the rear floor ribs using the nose piece extension for my Milwaukee rivet gun

I spent a lot of time with the flanges on ribs CF-RIB-001-L / R, which were not formed properly and made it impossible to slide the undercarriage channel into place. I had to bang on them with a hammer and shape with a seamer for quite some time; overall I needed to make the opening between the flanges 1.7 mm wider. After some elbow grease and a bunch of swearing, I got the channel in place.

The flanges on Rib 001 that surround the channel weren’t formed to correct dimensions so I had to bend them into shape
Finally got the channel to slide in!
Me and my rivet gun! Unfortunately I also had a use a manual riveter inside the channel since there wasn’t enough room to fit the rivet gun inside
Page E3 step 1 mostly done. I added the support brace too.

Rear Floor Assembly

I started fitting all the ribs I primed this past weekend to the rear spar carry-through assembly and floor skin. The fuselage is beginning to take shape!

I’m fitting the clecos from the top side, even though rivets go through bottom. Seems easier to do it this way rather than working upside down!
Turning the assembly on its side so that I can rivet from the bottom side

Center Fuselage Parts

In and around holiday events this past weekend I was able to put in a few hours on center fuselage parts. Not much to show, other than a bunch of floor ribs that have been cleaned and primed.

Speaking of priming – I found that I spend a lot of time on this step, so I’ve been looking for ways to speed this up. I am still deburring and lightly sanding parts as before, but I’ve switched up the cleaning routine. Rather than using a combo of simple green, water, acetone, and isopropyl alcohol, I’ve started simplifying to a one-step product that’s recommended by the manufacturer of the primer I’m using (SEM self-etching primer). The cleaner is called SEM Solve, which comes in a spray can and wipes off with a clean towel. So far the results are great – the primer is adhering well and the finish looks good. SEM doesn’t give guidance on how much of the cleaner you will need, but I’m finding that I need one can of SEM Solve per 4-5 cans of the self-etching primer at 3 coats of primer.

I switched to the gray primer color for the fuselage, for no other reason other than aesthetics — there are likely to be primed parts that are visible even after putting in the interior, and I think it would be nicer to see a neutral gray color instead of green.

Preparing the rear floor panel
Various ribs to attach to the floor panel
Rear spar carry-through assembly, to which the ribs above will attach to
Attaching an autopilot servo bracket to the main spar carry-through assembly. Access was really tight — I had barely enough room to get this relatively slim rivet gun into place.
Completed autopilot servo bracket

I have to put in an order to Aircraft Spruce soon, among the items I need to buy are:

  • Garmin GMU 11 Magnetometer plus connector kit
  • Garmin GSA 28 servo (x2) plus connector kit
  • Shielded twisted pair wire for the CAN connection to servos and magnetometer, as well as some normal straight wire for power & returns
  • Soundproof insulation for the interior skins (I want something more substantial than what is provided in the kit)

Anyone have guidance on how much length of wire I need to order, especially the shielded wire for the servos & magnetometer? There may be more wire I need at this point, like antenna wire for comms, ELT, etc., but I need to figure that out.