Side Stringers

[Jackal]

The side stringers show to be 1/4" x 1" spruce strips. Of course these will be supported at each station, but aft of the cockpit this is almost a 3' span between supports. Of course they can be supported at the between station diagonals, and in some cases this nearly breaks the span in half, but in some cases the diagonal crosses the side stringer not nearly in the middle of the span, making it seem like it will do little to support the span.

Are these side stringers typically glued to the fabric to help keep them straight. Without being glued to the fabric or supported every 18-20 inches or so I found in a test section that the stringer could be "pushed around" under the fabric to create a very unsightly mess.

What is the typical treatment, or for those of you flying, what did you do and what has been the result?

Thanks

[hatz215]

Mine is built according to plans and was not glued at the stringer and was fine for 23 years. If it WAS glued it could be easily pulled one way or another when you shrunk your fabric.

Steve G

[jwhanson]

We glued a 1/16 x 1 inch strip of plywood vertically in the middle of the bay to all the stringers.
John Hanson

[Jackal]

Hatz 215,

Thats a good point about the shrinking fabric pulling the stringers to the side.
You said you built according to the plans and it was fine for 23 years. The plans (as I can see) don't show whether the stringers are supported at the diagonals or just at the stations. Do you recall if yours was supported at the diagonal members?

Thanks

[Jackal]

John,

This 1/16 x 1" strip, was it also glued to the longerons or just to the stringers (I'm assuming you used more than one side stringer since you said stringers)? Also, I guess it was oriented so the 1" dimension was extending fore and aft on the fuse and the 1/16 dimension was inboard to outboard. In other words it was a flat piece wrapped around the curve of the fuse and not a piece cut to follow the curve. If so, I could see where this would keep the side stringers from moving up or down and looking crooked longitudinally. It would not give support from the shrinking fabric pulling them inward, but they seem strong enough in that axis (since that axis is 1" as opposed to 1/4" in the other axis). It is the "sagging" down between the stations that concerns me. If you did attach this ply to the fuselage and not just to tie the stringers to each other, what method did you use there?

Thanks for your input

[hatz215]

Mine is attached at seven points by 'L' shaped standoffs welded to verticals and diagonals starting at the vertical where sheet metal terminates back from the firewall and ending at the last vertical before the rudder post. What remains aft of that last vertical is pulled inboard by the fabric as it shrinks.

Steve

[mmcgrew]

I held my stringerss in place with temp supports on the inside. Once you poly brush and poly spray - they will be solidly glued in place.

Michael will fly in 2011

[jwhanson]

I added the 1 x 1/16 strips to keep the stringers aligned and spaced vertically. Unless you over shrink your fabric they shouldn't bend inward.
John Hanson