Here are the two flying things that I have on deck. I assembled the Quest water rocket and converted a Guillows Space Shuttle to launch off of my 1/2" PVC launcher.
On the Shuttle, I marked the bottom up to the installed rubber band hook that comes installed under it's nose. I carved and sanded a channel so a paper pressure tube would fit inside. I uses the tube from a fin-less air rocket that I previously built and trimmed it to fit. It is about 85% embedded in the Shuttle. I got tired of sanding and thought this was close enough. The tube is held in place with a couple of strips of tape. If it works well, I may sand some more.