What should have been 5 minutes of work turned into 2 hours! While attaching the control stick brackets (CF-BKT-009-X-C-) per sheet E6 of the manual, a mandrel broke off a rivet in a hard-to-reach location. It took me over an hour to remove it. First I tried drilling it out from the rear, and found that was nearly impossible. I switched to using a Dremel with a small grinding wheel to grind away the rivet face, until enough of the rivet was gone so that I could push it through as if I had drilled it out; that wound up working. All that grinding damaged the foam, so I had to replace the pieces and replace them.
There’s an interior skin that goes over the forward floor bottom skin, so I needed to install the insulating foam first.
Having completed page E3 (Main Spar and Undercarriage Channel), the next step is to attach the forward floor stringers. The rivets go up through the bottom skin, so I had to rotate the fuselage assembly onto its side. It winds up resting on the forward upright for the main spar carry thru, which I clamped onto my work table. Once I put it back down, I’ll add the insulation foam to the floor.
I’ve been quite busy the last week with family and friends so I only had an hour here or there to make progress on the plane. Most of the work has been on attachment of the spar carry-thrus to the center fuselage. Those are attached now, so I think the next step is to rotate the assembly onto its side to attach the forward floor channels to the bottom skin.
I had planned to spend Sunday doing the majority of the sealing work on the right fuel tank, but I discovered a crease in the leading edge of the skin. I spent a bunch of time trying to smooth it out, but I was not satisfied with the result. I have to ask TAF to send me a new skin, so unfortunately that means the wing is on hold for now.
Now I’m back to working on the fuselage. We had good weather today so with the remainder of the day I primed a few more parts that I will probably need this week. Afterward I decided to spend some time putting in the 1/4” “super” insulation foam I recently got from Aircraft Spruce. Like other builders, I opted to get denser & thicker foam than what is supplied with the kit.
At first I cut the material using a standard box cutter, which works ok but tears the material a little, even with a brand new blade. I remembered that I had a nifty rotary cutter made by Fiskars, which cuts this material without tearing and leaves a clean, square edge. I cut pieces to fit underneath the baggage floor and for the center fuselage floor between the seat ribs.
Next up will be attaching the main spar carry-through to the mid and front lower floor sections, so this assembly is about to start becoming quite big.
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.
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.
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!
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.
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.
I was able to log quite a few hours this past weekend, working mainly on the rear fuselage. First, I finished assembly of the tailcone, which is fairly beefy since the empennage control surfaces attach to it. Some rivets were a little tricky to set due to limited room.
Next, I cleaned and primed parts for the larger rear fuselage ribs, and assembled ribs 2, 3 and 5. Unfortunately I had to skip rib 4 for now, as I discovered a crack in one of the formed parts. Rib 2 didn’t quite come together as nicely as ribs 3 and 5; despite using the template, there’s some twist in the curved top pieces. I’m not sure if this is a problem yet – maybe the twist will get worked out once the rib is supported by the skin.
I moved onto building up the floor of the tailcone, reinforced with several longerons. I vaguely remembered a warning that the orientation of some of the longerons was incorrectly illustrated in the manual – sure enough, after researching for a good half hour, I found confirmation from reading Peter’s blog. Left and right longeron 902 are swapped in the CAD model used for the manual. By the way, this error is still present in the TSi manual as well, so please be careful and pay attention to the part number left/right digit, and take a look at photo below for proper orientation. If you read on in Peter’s blog, you’ll see that having these incorrectly swapped will cause a headache later on during the center/rear fuselage join.
Last thing I decided to work on was the luggage floor skin. Curiously, my fuselage kit included two skins: one for the parachute option, one for without. Also curiously, the skin for the parachute option was missing a few holes for a support channel specific to the parachute option, so I had to mark and drill those holes.
I’m holding off on riveting the supports in place, since this skin is supposed to have some foam attached to the bottom for insulation. I figure it will be easier to measure & cut the insulation without these supports in place, so I’m holding off on attaching for now. The kit includes foam, but I’m considering using a denser foam like other builders have opted for.
I’m not sure what to work on next. I don’t want to do too much more with the rear fuselage, since the next step involves attaching the ribs to the floor skin, and will start to become a fairly large assembly. I want to complete assembly of the right wing before I do that, but I’m on hold waiting for a replacement rear spar. I think I’m going to resume working on the right wing’s fuel tank, which I started in March but then set aside to finish up the left wing assembly.
I consulted TAF about my damaged rear wing spar, and they advised against repairing it so they will send me a new one. That limits how much I can do on right wing assembly for now, but we had some nice weather this weekend so I decided to prime the right wing skins along the rivet lines so that they’re ready to attach. I already have most other components for the right wing primed and ready for assembly.
I occasionally like to make sure the primer is adhering well, so I perform tape pull tests after the primer has been given a day to dry. I wasn’t too happy with primer pulling up on a recent part I was working on, so I made a slight process change – instead of using Scotch Brite to scuff the surface, I’m now using 400 grit sandpaper. I think the plastic protective sheeting that’s applied to the aluminum leaves behind an adhesive residue that the Scotch Brite doesn’t quite release. Wet-sanding with the 400-grit paper and water seems to work pretty well, so that’s what I’m doing going forward.
I decided to start assembling fuselage components, starting with the ribs of the rear fuselage. Assembly of these components was straight-forward.