Hydrodynamics of a Water Rocket

Applications of mass, momentum, and energy balances are central to the teaching of fluid dynamics. In this study, a model to determine the trajectory of a water rocket is given that is far simpler than the system of coupled partial differential equations that typically results in modern hydrodynamic problems of interest. This makes the problem an excellent choice for a student project—it can reasonably be completed with a day or two of effort. In addition to the fundamental mathematics, this problem offers opportunities in scale analysis, numerical methods for IVPs, balance principles in accelerated frames of reference, and the collection and assessment of flight test data.