1.6 Hours -
Before I can start fitting the wing skins, I have to make sure the wings are level and straight. Since the kit is pre-punched, a lot of the leveling work may be overkill, but it can’t hurt.
The first thing to do was to take the sag out of the wing skeleton. On the stands, the wings are only supported at each end. The weight of the wing causes them to sag in the middle once the ribs and aft spar are attached. To determine the amount of sag, I strung a piece of fishing line along the aft row of holes in the main spar. Both spars sagged almost 1/2″ near the middle.
A piece of fishing line strung across the spar shows how much the spar sags in the stand. The line should cross the lower row of holes.
To remove the sag, I built two, simple jacks out of wood blocks (2x4s glued together) and a threaded rod. At the top of the threaded rod is a coupling that, when turned, raises and lowers the overall height of the jack. I placed one jack under each wing at about the mid-point of the aft spar. As I turned the coupling, I could see the holes in the main spar come in line with the string…simple.
A simple jack, made from wood blocks and a threaded rod, is used to lift the wing from the aft spar.
Once the jack was in place, it was easy to eliminate the sag.
Next, I need to spend some time making sure the wings are level and without twist. The angle of the arms that support the main spar can be adjusted to level the main spar. However, I had yet to attach the lower supports to the wing stands. These supports are also made of some aluminum angle. The supports for the inboard end of the aft spar were simple…a 10″ piece of angle bolted to the stand. The aft spar will be clamped to the support, and the entire support can pivot on the single bolt that attaches it to the stand.
I installed additional supports on my wing stands for the aft spar. This is the inboard end.
The supports for the outboard ends of the rear spar were a bit more complicated since there is a rib that is flush with the end of the spar. For these supports, I used a 10″ piece of angle, but also riveted a small piece of sheet aluminum to one end of the angle. The aft spar rests on the sheet instead of the angle, and a well-placed clamp through the aft lightening hole on the outboard rib will hold the spar to the sheet.
I had to make the outboard support out of some angle and sheet aluminum. Of course, I riveted it together.
The outboard support in place.
The outboard support pictured from below.
Tomorrow, I’ll do the actual leveling. I’ll use my smart level to adjust the main spars to level, and I’ll use plumb bobs to make sure there is no twist in the wings. Once everything is level, twist free, and securely clamped, I may even get to hang a skin or two!
