Introduction

The development of hot water rocket applications requires a test facility. The AQUARIUS team designed a hot water test facility at the Institute of Aeronautics and Astronautics at Berlin University of Technology that enables rocket scientists to investigate several criteria of hot water discharge processes. Laval nozzles of different throat diameters can be integrated and measured. The following criteria can be investigated:

- Thrust of the hot water rocket motor
- Tank pressure during discharge
- Temperature of the hot water "propellant".

These properties can also be measured during heating and cooling of the propellant. For redundancy reasons the enumerated values are additionally measured by analog measurement devices. Thrust, pressure and temperature are transformed into electronic values by sensors . For the utilization of these signals the AQUARIUS team uses a personal computer that is equipped with a measuring transducer, where the analog signals are digitalized. A special software is then used to evaluate and to display the registered data. The main purpose of these activities is to investigate the influence of different nozzle shapes upon thrust and to improve the efficiency of hot water rocket propulsion.