Investigation on HREs through the years yielded to the identification of the low regression rate of the solid fuel grain as the limiting factor for the application of this technology to launch systems. In order to increase the regression rate, loading of fuel grains with energetic additives as well as changes in the solid fuel formulations must be considered and are object of the ongoing research projects. In liquefying fuel formulations, SPLab has developed the armored grain solution. The armored grain is a heterogeneous fuel formulation: a 3D-printed cellular structure is embedded in the liquefying fuel matrix. The printed structure provides mechanical reinforcement, with the liquefying fuel offering fast regression rates. The armored grain solution targets applications in launch systems where high thrust levels with simple grain geometries are a driver.

Hybrid propulsion feature relatively high gravimetric specific impulses.  This is a desirable characteristic for in–space propulsion applications where high thrust–to–weight ratio is not a stringent requirement (though volume–related parameters should be considered during trade–off). Urgent application as de–orbiting systems for decommissioned spacecrafts could benefit from HREs peculiarities as high safety, operating flexibility, reduced cost and modularity. SPLab contributes to these efforts via the vortex flow pancake (VFP) engine. The latter is a non-conventional engine pursuing high combustion efficiencies with small length-to-diameter ratio values and oxidizer vortex injection in the combustion chamber.