Hatz Biplane Association

Any clever ways to keep the wood fuselage stringers aligned and straight during covering? Mine have warped a little over time.

-Scott

Are you saying your stringers warped prior to covering or during the covering process?

Warped before covering. I was thinking of tying them up with rib stitch cord or making small wood blocks to hold them in place. After covering, I think the tautness of the fabric and the glue will keep the stringers from moving. I'm just wondering what others have done.

-Scott

Well, I'm obviously not there yet so I can't comment from experience, but could you make a couple of formers to attach where the warping occurs to pull them back into alignment? I don't know how comfortable I'd feel relying on the fabric to keep them in line, but I guess it would depend on where and how bad the warp is.

I assume you've already sealed the stringers, right? If not you could try to steam them and "unwarp" them.

Hi Doug,
We cut 1 inch strips of 1/16 plywood and glued them from the top longeron across all the stringers and down to the bottom longeron. This held them in place very nice. We used two on each side behind the cockpit.
John Hanson HC-012

Thanks John. I like the idea and will likely do exactly the same.

-Scott

Hi John,

The 1/16" ply vertical supports worked great. I had to use two per bay but I managed to get the stringers nice and straight.

Again, thanks for the idea.

-Scott

splischke wrote:Hi John,

The 1/16" ply vertical supports worked great. I had to use two per bay but I managed to get the stringers nice and straight.

Again, thanks for the idea.

-Scott

Scott, did you just clamp those in place as the glue set up, or use some other method?

I used cyanoacrylate to temporarily hold a ply strip to a stringer. The CA bond isn't very good but this worked in my favor since I was able to relocate the stringer if it was off. Once the entire stringer was straight, I epoxied pieces of triangular spruce stock to make the bond more permanent. The picture above doesn't show these spruce pieces. I hope this makes sense.

-Scott

splischke wrote:I used cyanoacrylate to temporarily hold a ply strip to a stringer. The CA bond isn't very good but this worked in my favor since I was able to relocate the stringer if it was off. Once the entire stringer was straight, I epoxied pieces of triangular spruce stock to make the bond more permanent. The picture above doesn't show these spruce pieces. I hope this makes sense.

-Scott

Makes perfect sense! Thanks. I was thinking that clamps might cause more bending/twisting, so this solution makes total sense... Simple and effective.