Getting a hybrid motor through its first static fire is the hurdle that stops a lot of projects cold, and Knights Experimental Rocketry has now cleared it. The engine, built for the 2023 IREC effort and named Jim, ran its first ignition outdoors on an open paved area, delivering close to 500 pounds of thrust over roughly twelve seconds. Pulling off a first burn on a team cast grain is, in my view, a real milestone.
The hardware reads as carefully put together. The motor is a vertically oriented cylindrical metal structure, held in a vertical black metal rectangular frame and suspended directly over an angled blast deflector plate, firing downward through a metal nozzle. Structural support struts, tensioned guy wires and plumbing lines surround the assembly, with tall blue compressed gas cylinders standing nearby. The oxidizer in this design is nitrous oxide.
Two details stand out to me. The propellant grains are sorbitol, cast by the team itself rather than sourced elsewhere, and that hands on approach to the chemistry is impressive. Once ignited, the motor throws a sustained vertical column of bright orange flame, and the burn comes with a loud roaring sound. Even after shutdown, residual flames kept burning on the steel deflector plate.
The open question is where this goes next. Jim is meant to propel Pegasus to 10,000 feet, and a first static fire is only the starting point toward that altitude. I am eager to see how the team builds on this result.
Project by Knights Experimental Rocketry. Watch it on their YouTube channel: