Rigging the Wings

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After 3 weeks of weather related delays (rain, 30 mph winds, and snow), I finally had a weekend with decent weather. I rolled the fuselage out of the garage for the first time. It took about 20 minutes before the first curious neighbor came over to talk about the plane!
The first step is to level the fuselage. I used 3 different bubble levels along the upper fuselage longerons and cross tie box. My driveway slopes in 2 different directions, so I needed to block both the tail and wheels.
The right wing was installed first. It fit fine, with no trimming of the fuselage skins required.
After the left wing is installed, the previouisly drilled holes in the spars are matched up and 1/4" diameter steel rods are inserted. Access is a bit tricky as well. Maybe a lightweight scaffolding set over the wing would have been the way to go here...
The pins are about 6" long, and bent into a "L" shape. The ends were ground into a bullet profile to make them easier to insert. Were I to make these pins again, I would have made the bent "L" portion of the pin about 2" long, and then smooth both ends of the pin. The sharp edges can bite your hands when you are wrenching on a stubborn pin.
After the wings were positioned on the fuselage, I re-leveled everything. I needed more cribbing under one wheel, but there was substantially more weight no the wheel now. So, I uses a 2x4 as a lever to lift the plane. I have used this trick before, and it works great.
Cribbing under the wheel to level the fuselage.
Fuselage leveled again using my VERY sensitive bubble level.
The rear spar was set according to the plans at 3 5/32" and then small wedges were used to hold it in place.
The rear spar carry-thru is pinned to the spars, and attach angles are drilled and clecoed in place. Only a few of these holes were drilled at this point. The rest will be drilled after the wings are removed and access is easier.
The level the wings, I turned once again to my water level.
The water forms a level surface naturally, so to level the wings, the tube is attached to the wing and the height of the water is measured above the trailing edge. It is easy to get the wings within 1/32" of each other.
The position of the wings can be adjusted in small increments by sliding the 2x4 in or out. This setup is a quick and easy adjustable support stand.
These are the specially modified drill bits that Hugh Beckman maintains. It is a set of 3 bits: 1/4", 1/4" to 5/16", and 5/16" to 3/8". I am told these bits have used by more than 60 Sonex builders.
The special thing about these bits is that the front has been modified to act as a guide, and does no cutting whatsoever. This keeps the bit tracking straight thru the hole. The last thing you need is to oval the holes, or go completely off course!
After checking, checking, and rechecking, the time came to drill the attach angles. The first step it to drill both the forward and aft angles to 1/4". The procedure goes like this: remove the rear angle and drill back to front, going thru the forward angle. Then, you reinstall the rear angle and drill front to back this time to drill thru the aft angle. Once that is done, all further drilling will be front to back (there is more room to work this way).
Here the 5/16" drill is just poking thru the other side. You can see the bit is still perfectly centered in the previous 1/4" hole. These bits work marvelously! From this point on, it's a simple matter of drilling up each side to 3/8".
A milestone is reached. Sonex #604 has wings! At this point, the wings come back off and go back into the garage. There's still lots of work to do on the fuselage prior to closing everything up and painting the interior.
Back in the shop, the rear spar carry-thru is removed. This allows easier access to the attach angels to finish drilling them to the fuselage.
With the angels drilled, they too can be removed and fitting to the carry-thru completed.
At this point, I still need to fit a few more stiffening angles, but it is much easier done on the workbench than in the fuselage!
The spar tunnel can now be re-assembled. I'll do one more check on things before closing up the tunnel for good.
Once again I ran into some tight quarters. I thought I would be able to get my rivet gun in here, but it's just a bit too wide. After considering several options, I decided that I'd rather install all the flush rivets while the spar tunnel was out of the airplane (where access wouldn't be a problem).
To do this, I needed to remove the forward wing attach angles. Luckily, I'm getting good at removing rivets, so this posed no special problem. I simply drill the head out with a #30 bit until it pops off. Then I use a punch to push out the shank. The hole shows very little deformation this way.


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Updated: 17 Dec 05