Tonight I made a couple more access panels for the wings. I had originally made enough, but I had used one to mount a Dynon pitot heat regulator, which involved drilling and dimpling 4 holes in the panel.
I then added the nut plates to the bottom outboard skin around the access panel openings.
I also countersunk the aileron attach bracket, where the pushrod attaches to the aileron. The pushrod is attached via an AN509-10 countersunk bolt.
Tonight I finished riveting the bottom wing skin. Overall, it all went very smoothly. There are a couple of over driven rivets in there, but nothing that I felt worth removing and re-doing.
Because it’s not possible to see the ship head or bucking bar when setting the rivet, I used a couple of spacers (small blocks of wood taped to the bucking bar) to help brace against nearby rib or spar flanges to help align the bucking bar. It helps to be ambidextrous with the rivet gun, and to have a long reach.
The last two nights I’ve continued riveting the bottom, outboard, left wing skin. Nothing to report, other than a minor issue when I realized the j-channel (short) that was installed by the quickbuilders was not match drilled. This makes sense, because it probably needs to be match drilled through the skin and j-channel. The annoying thing is that Vans doesn’t mention match drilling the j-channel at all in the instructions, so it’s easy to miss this step. Anyway, because I already had the skin half riveted on by the time I realized these holes were not there, I was limited in options, particularly when I comes to dimpling. I match drilled the holes, reamed them to #40, then used my pop rivet dimpler to dimple through the skin. This resulted in just enough of a dimple on the j-channel.
Last night and tonight I got started riveting the bottom skin onto the left wing. With the quick build wings, the inner skins are already riveted, as are the top and leading edge skins, so this one outboard skin is the only one that needs attaching. I had previously match drilled the j-channel, so I could jump right into riveting.
I started by clecoing the skin on and carefully checking the clearance with the leading edge skins. I’ve found that there’s a tiny amount of sag in the wings, which is corrected when the ribs are all aligned and clecoed to the skin. Getting the skin on, and then getting the ribs all straightened out by clecoing everything allows for some checking of clearances. I found that there’s outboard 18 inches of the bottom skin needed about 1/32 of material to be removed, so the skins can butt up to each other with no overlap.
Once I had the skin trimmed and rechecked, I got started riveting. It’s a bit of a stretch by yourself, but totally doable. I made sure to put plenty of padding down on the spar in case I dropped the bucking bar.
After two sessions (last night and tonight), I’m about 1/4 of the way through the riveting. I’m hoping I can knock this out within a week, it just depends on how much time I can spend in the garage.
Tonight I finalized the pitot wiring. I have a separate connector at the wing root for pitot heat. Since I had previously planned for a regulated pitot tube, I had three wires run to the pitot tube. With the unregulated model, I don’t need to use the third wire, so I’m leaving it in place as another spare wire.
I unpinned the pitot heat wire from the standard Vans wiring harness and connected it to the separate Pitot heat molex connector, then ran another ground wire from the pitot heat molex connector to the ground point on the fuselage. At the pitot tube end, I installed pins on the wires from the pitot tube, but held off on installing them into the molex connector. I need to wait until I have installed the mast, and the pitot tube, routing the wires through the mast in the process. If I install the connector now, there won’t be enough room to fit the molex connector through the mast.
Anyway, it was a fairly quick job to get this all finalized.
Tonight I bent, flared, and fit the Garmin pitot tube. Doing this for the second time (first time was Dynon) was a lot faster, and easier because I could use the Dynon tube bends as a reference.
There are some interesting differences in the Dynon and Garmin pitot tubes. The Dynon is noticeably longer. The tubes are marked “pitot” and “AOA” on the Dynon, but unmarked on the Garmin. I added some heatshrink labels to identify the tubes, after gently blowing through them to confirm which was which.
I’m installing the unregulated Garmin pitot tube, so there’s no controller box needed. The switch on the panel will turn it on, and it’ll stay on until switched off on the panel. This is how it works on most aircraft, and since I’ll hardly ever use it, simple seems best.
I’ve decided to switch back to working on the wings, so I can finish them up and then move them to a hangar. That should give me a little more room in the garage to finish the tail fairing.
It has been a couple of years since I worked on the wings, and a bit of a saga. My original quick build wings were impacted by the Vans primer problem, and I sent them back. But I had already made up the bottom skin for the left wing, including a cutout and holes for pitot mast and reinforcing. I had started riveting the skin on when the vans primer problem was announced. I carefully removed the rivets, and saved the skin. Then I decided to switch from Dynon to Garmin, which meant a new pitot tube. Unfortunately the hole pattern is slightly different and the screws are different sizes between the two. Since the Gretz pitot mast I have is no longer available for sale, I wanted to keep the original mast and bottom skin, and find a way to make it work.
On closer inspection, the holes are in almost exactly the same place. The different is the screw diameter, with Dynon using something like a 3/16 and Garmin a smaller #6-32 screw.
Because the screws carry a sheer load, and because there is plenty of material supporting the screw, I decided to use something JB Weld to fill the void under the screw heads. I coated the pitot tube mount and the screws in boe-lube and then set them into the filler. In the morning the filler had dried, and I backed the screws out, then cleaned up the filler with a file and some sand paper. I painted the filled area with some powder-coat touch up paint. The finish looks rough, but I’ll worry about it when I paint the plane, eventually.
It’s hard to reach the prop bolts with a regular crowfoot, so I bought a special prop-torque crow foot. I looked at a few options and decided on the Anti-splat Aero tool. It’s well thought out and did an excellent job. There’s a good video here that shows the tool in action.
The first step is to torque all bolts to 40 inch pounds, then to 60-70 foot pounds as the final torque. With the extension tool, I calculated 35 and 57 foot pounds. I measured the length of the arm of the torque wrench and the length of the extension and used the formula T1 = T2 * L1/L2 where T1 is the torque on the wrench, T2 is the target torque value, L1 is the arm of the torque wrench and L2 is the arm of the torque wrench plus extension.
Then final torque to 60-70 foot pounds (calculated as 57 on the tool). by holding the prop in one hand and torquing with the other I was able to torque all 6 bolts up myself.
The next step is to safety wire these bolts in pairs. That will be challenging due to the orientation of some of the bolt heads. Undoubtedly I’ll need to back some of these off to thread wire through and then re-torque.
Tonight I finally torqued the various nuts, and installed the cotter pins, on both the throttle and mixture cables. I ended up with slightly more cushion gap than ideal, but I think that’s ok. The mid-point of the cable travel is nicely aligned with the midpoint of the arm travel on the fuel servo.
Today I tested the clearance of the prop against the spinner, by rotating the prop between full fine pitch and full coarse pitch. The clearance was good, and never closer than about 1/8th of and inch. I
followed the plans and clamped two boards to either side of the prop and rotated using the boards as leverage. Since it’s hard to twist the prop and simultaneously observe the gaps around the prop, my son Julian helped me verify everything was good by taking pictures.
With that task done, I final drilled holes for the spinner cutouts and then riveted them into place.
