15/08/26 - Rivetting forward top fuselage skin - 28h
Rivetting of the F-7106 forward top skin has started on the fuselage. I took a long time to get to this point and kept postponing it for a long time but I'm finally convinced now is a good moment to close the top. Having to work under the panel will become more difficult now but all electrical wires are well organised and I'm pretty convinced I didn't forget any wiring. At some point you just have to get on with it.
Rivetting this skin is hard. Like in : "Really hard". You'll have to lay on your back underneath the panel with hips on the seat pan and the F704 bulkhead meanwhile killing your lower spine while reaching up with a heavy bucking bar way over your head.
The images below were taken over a period of multiple days of short rivetting sessions. It's just too tiring and painfull doing this in one long session.
Almost all rivets are difficult too reach, some seem to be impossible. You can't imagine the amount of cursing that happened over the last weeks, I'm sure I'm going to hell now.
The images below show you your working space I was in for the last couple of days...
I put some foam blocks on the ground and covered it with a blanket. It helps a bit but not very convenient. The light bulb in the back is not part of the plans :) It's dark in there with the top on and you will need some form of light below there to see what you are doing.
You have to get your hands with the bucking bar in between all this wiring.
A lot of the wires had to be disconnected again where possible to gain access to the rivets.
what a catastrophy...
I worked from center line fo the top skin towards the sides and from the middle point outwards to the panel and firewall. This seemed to work fine. Some builders have written messages that they have problems aligning the skin with the longerons and having difficulties inserting the rivets. I had no such issues using this techique.
Next image has the center line done. The correct order is first setting the line of rivets, then install the WD-643-canopy brace;
There is no way you can shoot some of the rivets with that bar in place.
After the center line was done, I had to do a final install of the WD-643-SS canopy brace (roll bar support brace). The lower tab of this brace is squeezed between the F-7108B angle and the F-7108A center fuselage rib. 2 AN3 bolt hold it in place. It took some time to get the holes aligned because the space between the rib and angle is really tight. On the nut side there is also the F-7109 reinforcement plat. A pin punch helps getting things aligned and in place. I had to disconnect a couple of items and remove my analog instruments again so that I could get access to the nuts with a torque wrench. Torqued them forAN3 bolts and put some inspection lacquer on. Also torqued the upper AN4-13A bollt holding the WD-643-SS brace to the WD-641 roll bar.
It's best to set the top row of rivets first. The nuts may make bucking those rivets harder if you install the nuts prior to rvietting.
Some days later I also had the outer lines done and was ready to start the side lines holding the top fuselage skin to the longeron.
Another shot of the rivetted top.
Work will continue but I ran out of AD3-6 rivets. Fortunatly a builder who meanwhile has abandonded his project could borrow me some.
The intersection of the skin and canopy roll bar side web is really tight. That's normal, I have seen multiple builders reporting the same issue.
Next day continued with the side lines. The rivest on the engine mount steel brackets are the most difficult here. You have to be very carefull not to disturb the top fuselage set rivets which are already present and pretty close to the new ones you have to set. Messing those up would mean having to set the top rivets (top longeron) and I have no idea how you can ever shoot or squeeze those again once that top skin is on. So be carefull here.
Especialy the last rivet on the intersection of longeron and firewall is pretty difficult to set. I used a small size tungsten bucking bar here and increased the shooting pressure a bit.
Another difficult spot where you'll need a smaller bucking bar is behind the F-902L and R bulkhead. The rest is pretty straightforward and the longeron gives a nice support surface for a regular tungsten bucking bar.
More towards the rear, I'm waiting with the last rivets as I have to rivet one of the windscreen clips first which interfered with the roll bar web.
continue on the passenger side.
I did a test fit of the windscreen.
Final rivets set also on the front passenger side. Only the last ones near the windscreen are remaining now. Those are also quite difficult and require the thin tungsten bucking bar in the locations underneath the F-721-B-L and R aft canopy deck. There is very little space here to position a bucking bar behind the unset rivet.
The two "extreme difficult" rivets are the ones on the intersection of the longeron with the F-704-D and F-704-C center sections of the F-704 bulkhead. They are underneath the canopy deck and aft canopy deck and only a very small width bucking bar will be able to access these.














