I was just wondering if you can lower the amount of dihedral on arf trainer kits. When I flew 12 yrs ago my trainer didn't have the max dihedral on it and I also enlarged the control surfaces which made it a little more aerobatic. Is this only something you can do with kits or are arf's easily modified?

DA

Depending on the plane and the building skills of the owner, many can be modified at least somewhat. It must be done carefully, of course, or you will end up with a weak wing.

If your trainer wing is built like most of mine were, you could easily duplicate the ply pieces that hold the wing halves together. Just take some of the angle out of the new ones. If yours is like mine.

The inner-most ribs on the wing halves will need to be adjusted as well.

I erroneously built less dihedral into my LT-40 wing. It still has self-correcting behaviors, but not as much.

somegeek

Some are easy & some are work, but it can be done for sure & you will probably like the result. One of the first things that I do in a trainer hop-up is to get rid of all dihedral. They don't fly like trainers after that, but they are still easy to fly (& they still look like trainers, so ya can fool some folks with your trainer-flying ability).[8D]

If your wing is joined by a steel rod, as is the case with some of the Hobbico RTF's, it can be very easy -- simply bend the rod until the wings lie flat & glue balsa wedges into the gap -- presto flat wing.

If the wing has a wooden joiner, you will have to cut it appart & put in a flat wing joiner, plus the obvious repairs & fit-outs.

A student of mine had a Goldberg Eaglet. When I built it, I took out half the dihedral, made it a taildragger, and installed an OS .25 on the front. It was a neat little sport flyer.

Dr.1

After an unexpected mishap with my Avistar snapped my wing at the jount, I rebuilt it perfectly flat with no dihedral. It REALLY changed the flight characteristics a lot. It is VERY sensative on the roll axis and has almost no self correction. I expected a little more sensativity, but not quite that much.

If you took ALL of the dihedral out of the wing, the reaction you got is to be expected.

Dr.1

Lesson learned. It is definitely in the "Advanced Trainer" category now!

Can you take out the dihedral?

You betcha.......
You can take out so much that you can call it ANHEDRAL.

This "trainer" is actually sold with sort of a wing joiner and root rib orientation that the wing glues together with something like about 1 degree of anhedral. We've gotten 5 or 6 of these at the field and they turn out with different amounts of "droop". The pictures are of mine. I cut a joiner that would fit the wing boxes (they were different dimensions inside) and give 2.5degrees of anhedral. I had to sand one the root ribs in a couple of places to get them to match up. And got a full 2.5degrees.

It actually rolls into rudder turns just like dihedral wings do!
It has a self-righting characteristic, but that's to be expected somewhat from high wings.
It has actually served fairly well as a trainer. I've had a low-time flyer who is really shaky with takeoffs and landings fly it and it was no extra effort for him.