Hey all,

SO Im building a tower trainer ARF. This is much more involved than my first ARF (nexstar). Well This one I have to make the dihedral out of the pieces of wood. Well I tried improvisins while epoxying them together and one piece moved a bit during cure time. Well not a huge issue, I could sand it down. Well after thinking about it, I always wanted to have no dihedral in my next trainer. (mind you that my nexstar was layed to rest during a mishap last year not involving myself) I feel I was doing good but wanted to lose the dihedral.

So my question is, How do I go about it at this point? DO I just cut 4 pieces of wood the same size as I had to start with but cut them straight and put them in the wing?

BTW, Did I mention the nexstar was MUCH easier to put together?

you can do that....I did it on an LT-40...but that airplane had a brace of hard wood that went insude the wing between the upper and lower spars both for and aft of the spar.
the airplane stills flys today and is trainning my son in laws father......

The center section ribs are most likely in an angled back postions to meet up when the dihedral is in place so this would need to be filled in. For started head to the hobby store and get a nice piece of ply similar to the brace and make a rectangular shaped piece the width of the original brace so it will fit in between the spars

If you sand down the brace made for dihedral that came with the arf you will lose strength in the final modified piece as it will have progressively less width as you move out to the ends. (see pic).

As for the center section, you could fill it with a balsa wedge. Since your new to ARFs, the easiest would be to find a piece of trailing edge stock that would fit best and place additional balsa shims for a good fit. Rough cut the piece as best possible then sand to meet the contour of the wing.

As a side note.. . I built the TT 40 kit some time ago and with all that dihedral you needed to use the rudder for a nice co-ordinated "grooved" turn. Removing most of it I feel will make a better flying plane. I would leave just a tad though as it it being a trainer with a high wing and very fat airfoil, I feel it will fly better than a zero dihedral wing.

I have a suggestion for filling the gap you will have between the ribs. It is a little work but it is not extremely hard.
Lay the wing paels flat on a workbench with the root ribs touching. Measure the gap at the top.

For my example I will assume the gap is 1/4 inch or less.

Get a piece of 1/8 balsa sheeting maybe 3 inches by 24 inches. If the gap is more than 1/4 you'll need thicker wood.
Stand the wing panel on the sheeting and trace the root rib twice.
cut slightly outside the line and sand to the exact shape of the wing rib.
Mark where the hole for the wing joiner needs to be cut.
Glue these 'ribs' to each wing panel. Use epoxy. Allow to cure.
Cut the openings for the wing joiner.
Lay the wing panel flat on the workbench.
Put some 80 grit. sticky back, sandpaper on something that is long and square. I have a 2 foot section of square aluminum tubing that is perfect for this stuff. I think it was originally part of a picnic table. It's 2 inches square, thin wall, very light.
With the wing panel flat on the bench, sand the new ribs until the thickness at the bottom is zero.
If you want a little dihedral, put a block under the wing tip to raise it and then do the sanding.
Do both wing panels the same way.
When you slide the wing panels together now, you should have no gap.

Hey thanks guys!

I should have said it is a tower 60 I guess. But still the same.

When I put it on the table flat, I have a VERY small space to fill there on the top of the wing. So shouldnt be too bad. Thanks for the help! Ill post if I have any trouble with it. SHould be pretty easy.

I will be ordering supplies in the morning and they will be in with the normal shipment on wednesday sooo, I should be able to get at it wed night. Unless I already have the plywood I need in the store. Hope I do!

After a lil more thought, I decided to not be selfish. I realized that this plane would be my get back into it plane for the year and I would go on to my escapade...I want to get some buddies into flying and the dihedral would help them out. SO i decided to keep it.