| Hours today: | 1.1 | Hours wings: | 233.4 | Hours total: | 332.3 |
| Rivets today: | 0 | Rivets wings: | 4169 | Rivets total: | 6248 |
Ran wires to the landing lights and crimped connectors onto the wires. Put in an earth connection on the main spar, with short wires going to the earth terminal on each light. Cleco’d on the remainder of the skins, on the bottom, ready for riveting.
| Hours today: | 1.7 | Hours wings: | 232.3 | Hours total: | 331.2 |
| Rivets today: | 4 | Rivets wings: | 4169 | Rivets total: | 6248 |
I cleco’d the top skins in place, then worked on the wiring from underneath. Along the main spar, I riveted one of the two brace pieces onto the rib. As part of the wiring, and the piping for the pitot tube, the instructions call for three grommets. The holes need to be about 12mm to get the big grommets through. There’s a problem, though:
Lack of space for drilling grommet holes
In the picture, an 8mm drill bit and the small battery powered drill only just fit into the space between rib 1 and the jig. To go to 12mm, I need to use a drill with a bigger chuck, and the bit is also longer. So where will it go?
I was too lazy to take off the jig, so instead, I drilled all three holes 8mm, then used a deburring tool to open them up to 12mm. In the photo below, the hole at top right is the raw 8mm hole; the hole at bottom right has been opened up to a little bigger than 12mm, and the hole on the left has had its grommet inserted. The lesson in all this is: don’t deburr for too long!
Results of deburring the hole larger.
| Hours today: | 5.6 | Hours wings: | 230.6 | Hours total: | 329.5 |
| Rivets today: | 296 | Rivets wings: | 4165 | Rivets total: | 6244 |
With the frames and skins all together, I checked the flatness of the ribs, and flattened where necessary. I ran the wires for the strobe and the landing lights in place to get lengths right, then riveted the ribs to the spars.
This is relatively easy, except for the five ribs under the walking area on the wing. When I assembled the right wing, I forget to rivet the flanges on the side of the spar to each rib, which meant a lot of painful rework. This time I thought it through. If the ribs are counted 1 from the root, to 4, the last full rib, then 5, the arched rib, I fitted 4, 3, 2, 1, 5.
Turns out that isn’t the best option. The flanges on the main spar get in the way of the riveter, so it is difficult to get the rivets in cleanly. If I were to do it again, I’d go 3, 2, 1, 4, 5. 5 has to be last, as the torque tube must go in before 5 goes in. The picture shows how I ended up doing most of the rivets in 4 from the wrong side.
Rib 4, showing the change in riveting direction
Rib 3 in front. It has been riveted to the flange, but not yet to the spar itself.
Rib 2 in front.
Rib 1 is a sod to get in. It is stiff metal, and there isn’t enough room. I took off the clecos at the trailing edges of 2 and 3 to give myself some more room, and with a bit of twisting, it all went together.
All went well, until I starting putting the diagonal component onto the rear spar. Then I realized I’d riveted the five spars under discussion here to the rear spar without putting in the small triangles in the picture below. Out came the drill. Sorted now. It just shows, you have to keep your wits about you.
Rear triangles behind ribs under walk area.
Then it was time to put the long diagonal piece onto the rear spar permanently. It all looks good.
View from below the rear spar in the region of the walk area.
| Hours today: | 0.8 | Hours wings: | 225.0 | Hours total: | 323.9 |
| Rivets today: | 0 | Rivets wings: | 3869 | Rivets total: | 5948 |
Added the rest of the skins to the test assembly.
| Hours today: | 3.0 | Hours wings: | 224.2 | Hours total: | 323.1 |
| Rivets today: | 0 | Rivets wings: | 3869 | Rivets total: | 5948 |
Test assembled the ribs to the spars with clecos and attached one of the bottom skins. It all seems to be looking good.
| Hours today: | 1.5 | Hours wings: | 221.2 | Hours total: | 320.1 |
| Rivets today: | 17 | Rivets wings: | 3869 | Rivets total: | 5948 |
I spent a little while cleaning up the main spar and the rear spar. They’ve been in storage, and not as well sealed up as they might have been. Lots of spiderwebs, etc. I assembled the components of the light, and countersunk all the holes on the main spar that have wing skins riveted to them.
Countersunk holes on main spar
| Hours today: | 2.2 | Hours wings: | 212.8 | Hours total: | 311.7 |
| Rivets today: | 66 | Rivets wings: | 3852 | Rivets total: | 5931 |
Ezee Bond worked very well to hold the aluminium plate in place in the wingtip, so I assembled and riveted. I managed to remember the connection for the wingtip light:
Wiring to wingtip light secured to last rib
It came out quite well:
There is a very slight gap between the front of the wingtip and the wing skin, so I slathered on filler. I also put filler in all the rivet holes on the top of the wing, and around the rivets.
I also spent some time mounting anchors and pulleys in the spare garage where the wing is going to be stored real soon now.
| Hours today: | 1.4 | Hours wings: | 210.6 | Hours total: | 309.5 |
| Rivets today: | 0 | Rivets wings: | 3786 | Rivets total: | 5865 |
I worked out that the best way to position the lower edge of the wingtip relative to the skin was to mark a line on the wingtip that should go in line with the edge of the skin. In the poor photo below, the original position of the holes is marked by the horizontal stroke, which would have been too close to the edge. The second attempt was the crosses, but I didn’t have faith in them, so I drew the line, then drilled a couple of holes while holding the line in the desired position.
Marking the edge of the wingtip.
After getting a couple of holes in the right places, I cleco’d the wingtip in place and started to drill the other holes. I very quickly found that on the bottom, the drill was getting through the composite, then pushing the aluminium strip away rather than drilling through it. Instead, I marked the desired drill positions with shallow drill holes, then took the wingtip off and drilled with a wooden block against the back of the hole to keep the alumium strip in place.
It didn’t work well enough, the lower strip just wasn’t well enough glued. I had used Pratley’s transparent pro expoxy, which comes in a joined pair of syringes. Something to do with the bottom layer just wasn’t good enough though.
Before fixing the problem, I countersunk all the holes, first in the countersink tool, which gave the aluminium the right shape, then by drilling countersunk holes.
Final countersunk holes in the wingtip skin. The aliminium layer is just visible at the bottom of the left hole.
Finally, I took the lower aluminium strip off properly, cleaned it and the wing and glued in back using Pratley’s Ezee Bond, advertised as specifically for metal and fibreglass. Once the two parts are mixed it has the consistency of honey mixed with chewing gum. It is also advertised as not needing degreasing, and seeing how tenacious it was, I can believe that. To hold the strip in place, I used clecos in all the holes.
Clecos holding the bottom aluminium skin against the wingtip while it is glued into place.
I don’t even need the aluminium to stay stuck for very long – just long enough to put the rivets in. Let’s hope this solution works.
| Hours today: | 2.5 | Hours wings: | 209.2 | Hours total: | 308.5 |
| Rivets today: | 0 | Rivets wings: | 3786 | Rivets total: | 5865 |
Marked up the wingtip for the nav and strobe lights and drilled the holes:
Drilled.
Rivnuts inserted
Then glued aluminium strips into the inside of the wingtip to give the rivets something to grab after the wingtip has been countersunk.
Aluminium strip glued to top skin. The mounting plate for the light is just visible behind. The fat pack of loose plastic bags is there to push the wingtip sides apart for easier fitting.
Aluminium strip glued to bottom of wingtip.
Once the aluminium was dry, I fitted the wingtip and drilled a couple of holes into the top. After I’d checked that they were in okay, safe in the aluminium, I cleco’d them in place and marked out the bottom. It turned out, all the holes were too close to the edge. I had to move the holes on the top slightly to get the bottom to fit nicely.
| Hours today: | 1.4 | Hours wings: | 206.7 | Hours total: | 306.0 |
| Rivets today: | 91 | Rivets wings: | 3786 | Rivets total: | 5865 |
Rivetted the end rib to the spars and skin. It is a tricky operation in terms of sequencing. First, I at attached the aileron support to the rib.
Aileron bracket attached to rib. The tape is to stop me rivetting things that have to wait till later.
The rib attaches to the spars with two brackets, but that brackets have to go onto the spars before they are attached to the rib, or there is no space to get the rivet gun in. I tried to be consistent with the existing rivets, but couldn’t manage it in some places, where I simply couldn’t get the gun in from the correct side.
Rivets on bracket to main spar, put in from the wrong direction. The rivet gun is too large to get in the leading edge of the wing on the top of the wing where the skin goes down rapidly.
The rear bracket on the rear spar. All the rivets come from the outside apart from the top one, where the nose of the gun wouldn’t fit past the skin.
Once the brackets were in, it was an easy job to rivet the rib to the brackets and the skin. Job done.
The nose of the wing, showing the rib rivetted to the skin.
sling056 