RE: Looking to convert this Cosmos!
Okay, lets look at the specs; 31", 285 sq inch area, and 14.5oz. This should fly just fine with a good .049-.061 engine. A Norvel .074 will pull it vertical and an OS .15 will turn it into a brick...
Save the .15 engine for something around 26oz and 350 sq inch, that's my advice...