Hybrid rocket engine is a thermochemical propulsion system in which the oxidizer and the fuel are stored in two different states of matter; typically, the fuel is solid, while the oxidizer is in the liquid state.
These features of a hybrid rocket make this system affordable, intrinsically safe, and flexible (throttling capability).
However, the slow regression rate is a major concern and a limit for the thrust level.
The potentiality of hybrid rocket propulsion could be fully exploited and the drawbacks overcome thanks to the novel armored grain approach.
The armored grain consists of a paraffin-based fuel matrix embedding a 3D-printed armor.
The research activities are carried out at the SPLab (Space Propulsion Laboratory) of DAER (Department of Aerospace Science and Technology), Politecnico di Milano.

Eager to learn more about armored grains?

Check out these publications:
https://doi.org/10.1016/j.actaastro.2020.07.003 ↗ (mechanical behavior)
https://doi.org/10.1016/j.actaastro.2023.02.027 ↗ (ballistic behavior)