Quad Engine Model Rocket Fin Can 34mm Tube
This fin can supports A10-3T engines and should vent all the ejection gases into the body tube. This allows you to create a 'hybrid' rocket. I have known these things to fly straight and far -- there is no flex in the fins so they fly very straight. This rocket will be featured at the NoVa Mini Maker Faire. Credit goes to Charlie Seested for doing the 'heavy lifting'.
Update: Added a BT-55 tube version that will take a single D Engine