Wing Keying

[rivers]

Thoughts from last weekend’s contest flying:

There were a few inconsistent flights where our models (Father and son’s)deviated from the normal power pattern. One factor seems to be the accuracy of placement of one-piece wings strapped onto the pylon’s wing platform.

What is the best way to key the wing position? I have seen pieces of half-round wood dowels glued on the wing bottom as location devices. Does this work well, or are there other ways?

[DAN BERRY]

I have started using 1/16 ply. About 1/4″ wide by a length that will glue to the LE and TE.
I put scotch tape ove the wing platform then starp and align the wing. Then poke the covering and glue the keys with med cya. I kinda hate gluing the keys to the wing AND the pylon.

[Dean McGinnes]

The challenge is to keep the wing and stab from shifting but allow them to shift and/or pop off on case of “terrain separation loss”.

The half dowels properly sized are a good compromise as the roundedness allows the surface to give on contact. I think Dan’s 1/16 ply would do the same. The advantage with his is it allows slightly skewing the wing if needed to fine tune turn trim. Easier to shave or shim something with a square edge than a rounded one.

[ARAM SCHLOSBERG]

A slanted wing will mess up the climb. Originally, my Oldelkamp’s “E-box,” with a two part wing attached with rubber bands, had no wing keys – as John does not believe in them. But I subscribe to the alternative school and added wing keys made from 1/8” bamboo rods sold as kebab skews cut in half, ¼” long. The covering was cleared and the keys are glued with DP 460 or DP 420 to the wing’s structure. (Don’t trust CA for structural joints.) The keys should abut plywood or hardwood on the pylon.

If the fuselage absorbs the landing – the wing will just shift forwards and then backwards. But if the dihedral break is impacted, the wing will rotate around the pylon. The rotation point is usually in the forward part of the pylon, as rubber bands slip more easily over the trailing edge. In such cases, the back dowel hops over the pylon or get sheared off. So far, only one rear key got sheared off.

[rivers]

Dear Friends.
Thanks for all of your helpful suggestions. I put 1/16 x 1/4 plywood keys on my Sloworm wing. Attached with epoxy; very easy to do per Dan’s instructions. The pylon rails are basswood faced with carbon cap strip material. Everthing looks good. Looking forward to a flying tryout soon.
Dick

[DAN BERRY]

You should be good to go. It ain’t really a load-bearing item.
When they knock loose, its usually only one. Its possible to fly with only the remaining 3 but you must do a visual each flight.

[Author]

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