A Short Discussion on Performance, Safety and Environmental Aspects of Gel and Hybrid Rocket Propulsion Systems

Rocket systems, which are operated either with gel propellants or with hybrid propellant combinations, show combinations of safety and performance benefits which are advantageous in comparison to conventional liquid and solid rocket propulsion systems. To these advantages belong a reduced hazard potential, thrust variation capabilities up to shut-down and re-ignition, and simplified handling characteristics if suitable propellants or propellant combinations are used. This paper gives a short introduction into the technology of both propulsion system types, which both use advanced propellants and propellant combinations to realize these benefits. The hazard potential of these two propulsion systems can thus essentially be reduced to the hazard potential related to the used propellants or propellant combinations itself, which are in tanks or are lining the combustor, due to their systemic advantages.