Only combat plane I ever folded the wings on (without outside help of course) was Riley Wooten's Vampire, (hmmmm is that the right name?), his early foamie with tagboard covering and no spar, or any longitudinal elements for that matter. It was a 2-piece wing, I think it had some splice pieces at LE and TE, mostly for alignment, and about a 6" "spar" in the center to anchor the bellcrank.    A little bitty 1/2" wide strip of tagboard over the center seam was supposed to hold it together. It flew great until it folded--and it always folded.  Hey it was early early foam (mid sixties?), what did we know?

  Yes and in all three age classes if I remember correctly.
  I flew a lot of them and never folded a wing that I had not previously punched into the ground and weakened it.

   Bigiron

You guys are better builders than me I guess... my brother and I had 4, 2 apiece, and folded every one within 2-3 flights.  Well, a couple just wrinkled but we put them aside, one more flight would have done it. We kept trying because they flew so well until...

I flew Riley's foam wing bloodsuckers (Vampires) in competition, (including the 1966 and 1968 Nats) for several years and never had one come apart in mid-air.  The secret to keeping them together was using plenty of glue and insuring solid attachments in joining the wings.  My choice was Hobbypoxy and Elmer's White Glue.  Vampires performed extremely well if set up correctly.  Riley won First Place at the 1968 Olathe, Ks Nats Open Combat Event, flying his Vampires. My Vampires, built from Riley's Flite Line kits, got me a 5th place finish behind "The Man" that year in Open Combat at Olathe.  The Flite Line Vampires were first class airplanes for that era, if built correctly.