The trajectories of large fire fighting jets

This article describes a computer simulation of the trajectories of large water jets which allow the effects of changes in initial velocity, elevation, nozzle diameter, and head and tail winds to be examined. The rather limited information on aerodynamic drag of large jets obtained by other workers is used. The predicted trajectories compare well with the limited data available in the literature.The results also show that for a given flow rate an optimum pressure, and hence an optimum nozzle diameter, exists for maximum throw distance which has important implications for the design of the whole system including the pumps. The optimum elevation in still air lies in the range 30–40°. Wind effects are shown to be very important.