Wing Building Woes...

[Gimpster]

I do not know why but I seem to have trouble building the wings for these Airfoilz planes. I just can't seem to get a straight and true wing. My first kit ended up with some dihedral due to using an old banquette table with some sag in it. Now I am working on my second plane and the spar is anything but straight and true. It's straight but not flat. This time I built it on an hallow core door which is the most level build surface I have access to.

This time I don't have a nice small dihedral like last time. The boards started our not straight. It took some time but after working with the wood for some time I ended up with mostly straight pieces. After gluing however this time I have a spar with gentle dihedral in the center, which gets more aggressive towards on tip and has a slight negative dihedral at the other. I am getting a bit frustrated with building these spars. I am sure it will have only a small effect on the flight performance but it's still going to be noticeable when performing aerobatics and trimming it out will just cause issues in other places.

So is there any way to straighten the spar before I finish wing assembly or am I stuck flying another non-true airframe until I eventually crash and destroy it like the last one? Although this will be easier to repair then the full-fuse I had last time.

Wayne (Gimpster)

[bills]

Hi Gimpster,

I know what you are talking about. When I built my first one, an Edge, the wing actually came out opposite of yours with a little anhedral angle. Not much but you can see it if you look close. That plane is now about four years old and is still one of my favorites. The next one I built I was more careful when I glued up the I beam. If there were curved balsa pieces I would try a glue them up with curved pieces opposing each other to help straighten them out. If I still did not get them straight, I can get them pretty close when gluing them inside the wing. I use a long straight edge slid through the wing to get the I beam straight forward and aft with the marks on the wing tips. The plans for the older planes called for glue the entire length of the I beam when gluing them in the wing. When it is done this way most any dihedral or anhedral can be removed before the glue sets just by carefully bending and holding the wing in the direction it needed to go until the glue set..

The Bipe I am building now only calls for glue on the last couple of inches of the I beam inside the wing and just a spot through a hole at the center. I am not sure if the above method would work glued in this manor but I didn't need to try it. I did have a couple of curved pieces in this kit but they came out pretty straight when glued opposing each other.

If all else fails and the spar does not come out like you want it, (before you glue it in to the wing) you can easily get the balsa to start over at your LHS or many craft stores. Watch what you buy though because odds are you will pick up at least one curved piece. :)

Bill

[Gimpster]

Well a lot of weights and a flat table dealt with most of the curves. Once assembled it was dam near straight. I glued this one differently, then is called for. I got the spar positioned and then flowed a bead of CA down the seems where the spar met the skin and it seems to have formed a nice strong hold.