Just a simple session today priming the two halves of the flap piano hinges.
The flaps are mounted using piano hinges and there are two ways in which the pins can be configured to mount the flaps. The first is to run the pin from the inboard end all the way through to the outboard end. Drill a hole in the steel aileron and push the pin in there. The problem is that the flap pin is very difficult to push through all those eye holes while holding the flap at the same time.
Option 2 is to remove two of the eyelets in the middle of the hinge and split the pins. It makes it easier for the pins to be fitted and removed if need be. The pins need to be cut, bent and chamferred at the ends so they fit more easily. the bent ends locate in the middle of the flap. To fix the pins in place I drilled three holes in the flap brace for a number 6 screw and nutplate and rivets too.
It was a surprising amount of work to get the flap pins done today but at least their done.
After that I mounted the right flap by riveting the second half of the piano hinge to the wing structure and fitting the hinge pins which worked a treat.
All the parts for the flaps have been primed and left to cure for a few days so today is a good day to rivet the flaps together. It’s always a fun but nerve racking time because so much effort has been spent so far and one small mistake could mean a big do over.
I started with the bottom skins and riveted the 4 inner ribs to the end of the bottom skin and then to the rest of the bottom skin.
Next I riveted the reinforcement plate to the end rib.
Then riveted the inboard end ribs to the bottom skins but left the outboard just clecod for now as they can be reached with the squeezer.
Once that was done I made a couple of V blocks as per the instructions and then put the top skin on and sat the assembly in the v-blocks.
Once it was in the v-block I was able to rivet all the top skin rivets with the tungsten bucking bar and rivet gun. There are a couple of rivets at the very lowest point that must be pop-riveted because of their location but the rest were do-able. Once that was done I riveted on the rear spar using blind rivets as per the plans. I had quite a bit of trouble with the rivets near the reinforcement plate as the holes were too close to the bend and so the rivet puller simply wouldn’t fit. In the end I worked out that a single eye from a piano hinge was the perfect left the raise the rivet puller high enough to do the job. Unfortunately with all that head scratching I forgot to take any pictures until both rear spars had been fitted.
The last job was to rivet on the piano hinge. To do this I needed to change the yoke. There are two pins with ring pulls that hold the yoke in place and today, for some reason, I forgot to put both pins in. As I started riveting there was an almighty crack and the rivet squeezer was toast! The picture below shows the broke part either side of the spring. That part is supposed to be one piece. 🙁
Luckily I still had my pneumatic squeezer so I was able to get the piano hinges finished.
The flaps look good but I’m not 100% happy with the left flap where I had to drill out a blind rivet as it has left a bit of a mess. I will check with my inspector and see if he is happy with it as it is or if he has any ideas on fixing it. A long, but productive, day today.
Still on a high from finishing the main wing structure and ailerons last week I couldn’t wait to get started on the last major assembly of the wing kit, the flaps. First I found the spars, deburred the edges and the lightening holes. Then I found the 12 ribs and deburred those two. Then cleco’d the whole assembly together.
Next the instructions say to match drill the ribs to the spar but there is too much movement there to get an accurate drill. I decided to cleco both bottom and top skins in place so they would hold the ribs firmly in place while I drilled. All this effort is to try and reduce/prevent twist in the flaps. The problem is the top skin curls over and blocks the top holes in the ribs. I got over this little problem by using my angle drill with the smallest possible bit.
Once that was done I removed the top skin and called it a night.