Air Rocket and Fin Collar

I designed this rocket and fin collar for a great air rocket launcher I got from the Maker Shed (http://www.makershed.com/products/compressed-air-rocket-launcher-v22). I wanted my second grade students to be able to see the rocket in flight without fins, and then to be able to design and easily attach their own cardboard fins for testing. The rocket has a small ridge and fits in a groove on the inside of the collar to prevent spinning during flight. The air rocket is quite powerful, so we wear eye protection, and the kids stand well back. The difference in flight is obvious, and the students enjoyed the whole experience very much.