## Water Rockets - the transportation system of the future

Water rockets have been fascinating children and adults alike throughout the world for some time now, possibly because they are conceptually simple, requiring an ingenious combination of "exotic" components such as plastic soda pop bottles, water, a bicycle pump - and their behavior is totally unpredictable. The University of Leeds in England have a Water Rockets page which includes a number of fascinating video clips and photos of various rocket launches and tests. Their video clip of the first documented manned water rocket launch in Japan made us realize the great potential of the water rocket as the possible transportation system of the future. A youtube video of this historic event has recently been made available on the web.

During 2004 Dr Ken Halliday decided to use Water Rockets as the theme project for the ME100 freshman class "Introduction to Mechanical Engineering" - assisted by Dr Andy Foley and the ME398 Junior Lab. In the following split second sequence photographed by Dr Halliday we see Dr Foley demonstrating a typical launch sequence of one of the student rockets:
 Here we see Dr Foley giving the countdown before launch. "Five.. four.. three.. two.. one.. ignition..... ...BLASTOFF!! This doesn't seem right - during the "thrust" phase at least it should be going up... Now where did that rocket get to....?

The students came up with some delightful artistic designs, for example #19 - the "Hula-hula" rocket:

We have decided to do a computer simulation of water rockets as the theme exercise for this quarter. This will spread over six computer programs of increasing complexity and will bring home the advantages of using Object Oriented methods in engineering programming. In this first exercise we will simply define the Rocket class in terms of its private and public variables, as well as the constructor for creating a specific object of that class. In forthcoming exercises we will develop methods to evaluate the compressed air volume (why?) as well as the acceleration, velocity and height of the rocket as functions of elapsed time from the launch. However before we can continue we need to go through and attempt to understand the rather complex analysis associated with this seemingly simple system.