Part 2 o' 7. Avast! This video shows t' construction sequence for makin' a Rogallo win' glider that is boosted into t' sky by a model rocket. Blimey! They are often called flexie gliders because t' win' is flexible and can be rolled up and stored in a small space. Ahoy! In model rocketry, they are used in t' National Association o' Rocketry's flexie contest.