Burning Behavior of Aluminized ADN/PSAN Propellants

Solid rocket propulsion is used in the first stage or boosters of space launchers. Three oxidizers are available on the market, which can be used for the preparation of composite propellants: Ammonium Nitrate (AN, NH4NO3) or its phase-stabilized (PSAN) version, the widely used Ammonium Perchlorate (AP, NH4ClO4), and the relatively new Ammonium Dinitramide (ADN, NH4N(NO2)2). To our knowledge, ADN-based solid rocket propellants are used by the Russian for the intercontinental ballistic missiles only [1]. The first application of ADN in Europe is in a liquid monopropellant (LMP-103S) [2]. The current state-of-the-art composite propellant used for about 50 years is based on the oxidizer AP. The aims of new developments are the improvement of the delivered performance and the reduction of environmental impact. Therefor AP must be replaced by a chlorine-free oxidizer. ADN/GAP-based solid rocket propellants were systematically studied in the HISP project (High performance solid propellants for In-Space Propulsion), a threeyear collaborative project financed by the Seventh European Framework Project. It turned out that this kind of propellant burns too fast for space exploration. Thermodynamic calculation shows that a blend of ADN and AN is able to replace the AP. This dual-oxidizer system bonded by an either inert or active binder and loaded with metal fuel, is a potential candidate for space solid rocket propellant. In the framework of the GRAIL (GReen Advanced hIgh energy propellants for Launchers) project, supported by Horizon 2020 program, propellants with ADN/AN oxidizer are evaluated. The paper focuses on the properties of ADN/AN/GAP/Al propellants and their burning behavior.