We are fascinated by the hybrid rocket engine which [Ben Krasnow] built and tested in his shop. It is actually using a hollow cylinder of acrylic as the fuel, with gaseous oxygen as an oxidizer.

Hybrid rocket engines offer perks from both worlds, with simple solid fuel and the ability to throttle down by regulating oxidizer flow ... get to a flight ready engine. His previous experiments ...

Engine design optimization ... and implementation of hybrid rocket propulsion systems. These include addressing low-frequency instability, managing the shift in oxidizer-to-fuel ratio during ...