Vertical stab tip

Drilled pilot holes for the fiber glass tip. Filing the inside front and trying to push it as far back as possible should allow it to fit without having to cut it up in the front.

Flaps and vertical tail

Finished the flaps and riveted/bolted the vertical tail.

Found out how to achieve correct holes so the CCC-42 rivet stems don't get pulled through. First I filed my 120 degree dimple die (used in a C or squeezer) a bit more so that the male end enters fully a hole drilled with a #31 drill bit with no friction or without having to use any force. Then I revisited what is actually said about deburring of holes that is to be riveted. In the book "Standard Aircraft Handbook" by Larry Reitmayer it says that burrs under either side of the rivet is no concern, but should be removed if the sheet is not to be used immediately to not cause scratching when stored or injury to personnel. Drill chips between sheets should be removed. Removal of any "appreciable" amount of material from the edge of the rivet hole should not be done. Although I have not removed any appreciable amount, I have used a normal rotating deburring tool. So, with the trimmed dimple and deburring with a glove, a perfect rivet with a #31 dimpled hole.

Since Lasse has not yet shown up, I have yet to rivet the skin on the horizontal stab. The h-stab has #30 deburred and dimpled holes, and none of those rivets will actually fit correctly. I still have the choice to use solid rivets and Cherrymax. I will see.

Flaps

Drilled pilot holes in the flaps and hinges

Rivet binding strength

Spent this evening on investigating different ways of drilling for the countersunk rivets. Some info can be found here and here. The issue is mainly what drill size to use, #32, #31 or #30. I made three samples that I wanted to tear apart in the vice. It all went well until I found out the very hard way that my vice is very good for pushing things together but terrible at pulling things apart :-) (when pulling, the big bolt just comes out not taking the rest with it).

Then I tore them apart using a flat screwdriver and found that the aluminium sheet broke before the rivet fastener. Doing this I mounted them flat standing in the vice, so that one part was in the vice and the other part including the rivets standing on top. I then got the idea of using a hammer sideways, parallel to the surface, to get a torsion (and shear) load around the rivets, that will then be felt as shear on each rivet. So I took what was left of the samples and made new rivet connections. This time I used straight forward 30, 31 and 32 drill bits. I used my squeezer on the 30 and 31 holes and the "simple" pulled dimple die on the 32 hole.

The result was that I had to bang from side to side and totally bend the pieces out of shape to get them apart. The #30 drilled eventually separated because the shop end of the rivet got pulled through the hole. The #31 drilled did the same, but the plate also got torn up. The #32 drilled separated because the sheet broke while the rivet bonding was intact.

So what is the strongest? For all the samples the aluminium plates had to be hammered way past yield strength back and forth several times. The pieces also got bent, which means there was tensile stress in addition to shear stress. So who knows? The #32 sample seems to have the strongest bonding, but it was also the easiest to brake apart, so it could very well already be fractured from the previous abuse with the screwdriver. Besides, #32 holes are totally impractical because a 1/8 cleco won't fit and the 3/32 cleco is too loose. The only possible way is to match drill to #40 or slightly larger, then un-cleco, drill up to #32 and dimple in one go because the 1/8 clecos fits the 32 holes after dimpling. Using solid rivets is also an option of course, they are not nearly this sensitive regarding exact hole size.

All in all, when the pure pull test didn't work out, I didn't really get that much more knowledge other than knowing that the rivets are not likely to pop out of the aircraft unless the aircraft is bent and twisted beyond recognition, no matter what drill size is used. However, the ball on the stem is never pulled through when using #32 drill bits for whatever that is worth.


Also tried to polish the Topgloss BR with Biltema rubbing by hand. The result was surprisingly good. Really nice and shiny and smooth.

I then tried to polish it with Jotun Hardwax and also some old car polish I had laying around, but then it got all milky. The tech sheet says that polishing the Topgloss BR may cause milkyness, but not Hardwax, the tech sheet is obviously wrong.

If I can rub/polish this polysiloxane paint this easily, I probably also can roll on some polyurethane just as easily and hopefully be able to polish it without getting this milkyness. I begin to suspect that this polysiloxane Topgloss BR has been rushed out into the market before it is fully usable.

Right aileron

Left aileron

Finished riveting the left aileron. The led was cut according to the plans. The plans suggests that the led is over sized and need to be trimmed. My led on the left aileron needs to be enlarged, and this is with no paint on! Still have not decided paint or no paint, so fine trimming of the led counterweight have to wait in any case.

Aileron and flaps

Trimmed and drilled the led counterweights. The led sounds easy to work with, but is actually very laborious and difficult. Destroyed two drill bits and I hope my vixen file is still OK. Deburred, dimpled and primed the ailerons, but the primer was still a bit moist here and there, so I let it cure overnight.

Started with the flaps, the last moving surface. Cut to correct shape and measured up the position for the ribs.