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ObjectiveSloshsat FLEVO is a small free-flying spacecraft that has been ejected from a Hitchhiker-C facility on the US Space Shuttle. It has primarily been designed for the investigation of forces exerted upon a manoeuvring spacecraft by liquid slosh in a partially filled tank.
ContextThe Sloshsat FLEVO development has been performed in the framework of the ESA Technology Development Programme (TDP) Phase 2 and the Netherlands Agency for Aerospace Programmes (NIVR) Research and Technology (NRT) programme.
Simulation of the spacecraft dynamics and preparation of the control laws has been performed with the Sloshsat Motion Simulator (SMS). SMS was an original development from NLR and is operated in the EuroSim environment.
Role of EuroSimThe Sloshsat Motion Simulator SMS has been coded in Fortran and has been operated in the EuroSim environment. It predicts the 3-D motions of the tank and of the liquid center of mass. The liquid center of mass is not constrained to a surface but can be anywhere in a spherical volume of the cavity of radius R. This freedom is a consequence of the liquid model: a sphere of constant mass but variable radius, named 'slug'. The slug has variable moment of inertia and internal energy from capillary (surface) potential and from kinetics. Its resonance frequencies are also variable and have values between those of liquid drops and bubbles of slug size.