I've got to share my Suhkoi SU-31 wing story. It was a used plane when I got it. My first flight with it resulted in a stall and crunched muffler. I rebuilt that and had antother go and it ended up with some damage, I had pinched a hole in the fuel line that became a problem about 2 seconds after lift off. Trying to avoid the barbed wire fence at the end of our field, I stalled again and crunched the cowl and ripped off the landing gear. Last week, I finally got it all back to gether and the third time wasa charm. Ihad my buddy test it out and it was a good flight . I followed up with two good flights and easy landings. Life was good.

I 'm cleaning things up to go home and I discover what looks like a loose joint between the wings. Closer inspection proved it was bad. Epoxy joint broke loose. Used the wrong epoxy, Bad assembley on the other guys part. Well, when I finally dismantled it to see what was wrong, the root ribs which were 3/16 or 1/4" balsa were joined in OKat the glue joint. THe balsa was all broken up. The "hardwood" joiner was snapped in half at the center. The only thing holding the halfs together was the shreaded balsa in the two root ribs.

Guys, 5 minute epoxy, 30 minute epoxy 48 hour epoxy and it doesn't make one bit of difference, the wood is the soft spot in the joint. It doesn't matter if it is the strongest epoxy know to man or hardware store 5 minute, the epoxy is stronger than the balsa and stronger than the glue in the lite ply. The main reasion to use the 30 minute as Grey Beard and Ken stated, is it gives you more time to get things buttered up and clamped and taped together before the epoxy kicks off.

I expect the damage to my wing was when I tried to miss the fence and stalled and clipped a wing tip on the way to crunching the cowl and landing gear. The epoxy had absolutely nothing to do with the joint coming apart.

Don