WaterRocketFun is a Water Rocket Simulator for Fun & Science Studies. It help students and rocketeers understand the physics of water rockets and how to optimize their water rocket launches to obtain the highest apogees. The interface is designed to be easy to use and understand. But dont be fooled by the programs simple layout, few if any of the other simulators you may find are as accurate. Under the hood this program is pretty sophisticated and thorough.
The methodology includes both incompressible and compressible fluid mechanics along with a fair amount of thermodynamics and numerical methods to provide accurate water rocket apogee predictions.

The license of this software is Freeware, you can free download and free use this calculator software.