I'm currently working on a bottle rocket for my physics class. Instead of taking the assigned experiment, a friend and I have chosen a side experiment to work on. The experiment: Create a rocket using a 2L bottle as a compression chamber and compare the time required to reach the apex of its flight using different 0, 10, 20, ..., 60% water and compressed air @90psi. Now I've created a sketch of what I, using various forms of research, believe to be a good start to my rocket. I've gone with a parabolic nose cone which is recommended for subsonic flight and what I feel is a good fin location. The mass of the rocket comes in at 175g dry. What I need help with is some of the finer details. I cannot change the size of the nozzle which must stay at 22mm to fit the launcher. The rocket is launched straight up. I'll include a sketch. What can I do in order to make the rocket fly higher?