The butterfly was my first successfully built and flown kit. I didn't like the way the wing built with the webbing installed inbetween the two spars. At the time they called it an "I" beam wing. Was a pain in the patootie to get the webbing cut for a perfect fit between the spars. First flight was with a .15 Waaay underpowered, barely looped, if my instructor hadn't been there would have "re-kitted" itself. Had an os-20 (or was it a 25 - 16 years ago?) and now would literally fly out of my hand. My 15yr old son and I qualified on it at the club and spent 20 or so hours in the air.