Finished up drilling

Finished up-drilling. The inner rivets close to the fuselage pose a problem. It's way too little space for my rivet pullers. Then I remembered I have this super CherryMax puller with all sorts of heads, also one especially made for tight rivets. Unfortunately it will not grip the SS rivets, so I have to use CherryMax.  

Updrilling inner wing skin

Started updrilling the inner wing skin to 1/8. I use drill #31 on all flush SS rivets, and #30 on all non-flush SS rivets and all solid rivets (as I have used everywhere else). After having laid on my back on the concrete floor, I decided to purchase one of those car mechanic "on the back" chair/bed. But then I remembered I had some old garden chairs laying around...

Flaps hinges

Marked up and drilled the flap hinges. Not exactly huge slotted fowler flaps, but I guess they will do their job just fine for landings.

Inner wing skin

Finished match drilling the inner wing skin on both sides. I had help from my son, impossible to do for one person. Now it's updrilling to 1/8, dimple and de-burring etc.

Inner wing skin

With the outer wing in place and "lasered" up and the inner wing skin on, I match drilled all holes on the main spar and aft along the ribs. Then removed the outer wing, insert the skin doubler to finish the rest.

Wing measurements

Placed the laser under the aft fuselage. Then it will reach all corners. Then I measured the height from the point of measure down to the level laser light. For the tip leading edge I used a rod the fitted into the little hole in the ribs. Found out it was completely impossible to eyeball the leading edge. For the mid point leading edge there is a small hole in the skin. At the trailing edge I just measured from the bottom.

The idea is that when difference H1 - H2 is the same for all cross sections, then the wing is straight. I needed to rise the right mid trailing edge about 7 mm, then everything will be straight. Now I can drill the mid skin in place, with the outer sections on (at least some of the holes), and the wing will be straight.

   

Measuring wing twist

Everything was ready to put on the outer wings and measure the twist. I can see that without rivets, the inner wing can be twisted a little bit. I measure the leading edge and the trailing edge with a reference to the laser level light. If the difference is the same for both wings, it should be straight. It looks fairly straight, but if I twist it, it will stain in a new position, about 3-5 mm off. This is with clecos on the trailing edge. Two holes on the main rib, one towards the fuselage and one towards the outer wing, will hold the twist. Just a bit fiddling and it will hopefully be straight. It is very straight, but I will try to do it as good as possible, and hold it in place with support fixture.

Inner wing ribs and skin

Bolted/riveted on the inner wing ribs and started trimming the inner wing skins. The inner wing ribs was finished from some time ago.Lots of crashes rivets vs bolts and similar. I need to make several new holes on the trailing edge. Also the wing bolt handle clip needs to be shifted further outward and further in. This will require a piece of skin doubler.

To get room to drill and rivet, the landing gear has to be removed. Luckily I have the AirWard removable wind shield kit, or this would be a real PITA.

Left aft pin

And then the left aft pin.

Measuring wings and aft pin

I tried to measure if the wings were straight, and got a little shocked when I found that they were twisted. I measured from the wings to the floor. Then I thought, just maybe, the floor isn't all that straight (When it was made I knew it wasn't completely straight, but...)

Borrowed a leveling laser from the lab, and rigged it up with the aircraft. The laser was in front of the aircraft and the light was directed to the wing tips, and any other point I liked to check. The wings are straight as can be. At least as straight as it is possible to measure with that laser. Phuuu :-)  (I still have to measure the trailing edge to be really sure it is straight, but I think it is. When measuring from the floor, it was the leading edges that were off.)

Then drilled and reamed the right aft pin hole. The pin shaft needed to be bent a little to let it go easily in and out.

Upper left wing bolt

Drilled and reamed the upper left wing bolt. Perfect fit with the adjustable reamer.

Thinking about the wing pin handle, it is strange this isn't explained in the drawings. The pin is a perfect fit. It can only slide in and out There is no way it can rotate around the pin hole (in pitch direction). The wing pin handle rotates at the upper bolt. For a tight fit of bolts, this will of course not work, because the pin will be bent and will bite. This means the bolt holes must be enlarged. I made a drawing showing the different direction of the lower wing pin handle bolt and the wing pin bolt hole.

Reaming left wing

The lower pin hole.