“I’m most grateful for the knowledge gained at the Zucrow Propulsion Laboratories, which provided students with invaluable hands-on experience related to the design, analysis, build, and hot-fire testing of liquid rocket engines. This solid foundation was used extensively in the design, analysis, development, and flight phases of the Raptor and Merlin rocket engines at SpaceX.”
John Tsohas has been instrumental in developing the SpaceX Raptor engine, which powers the reusable Starship launch vehicle. The transient timing that his group developed is crucial for the successful startup, shutdown, and steady-state operation of this large liquid bipropellant rocket engine. He was also intimately involved with the systems design and analysis work since the early days of the Raptor engine program. As manager of the propulsion fluids group, he is responsible for modeling the fluids/thermal systems on the Raptor-Booster, Raptor-Vacuum, and Merlin engine development programs at SpaceX.
At Purdue, John conducted NASA-sponsored research modeling time-accurate behavior of liquid rocket shear coaxial injector elements, with a focus on combustion instability. John was also involved with a 500-lbf thrust liquid bipropellant rocket engine which incorporated a novel altitude compensation nozzle. These studies included fabricating solid propellant nozzle liners believed to be the first of their kind. He also was involved in design and hot-fire testing of an experimental 10,000-lbf thrust rocket engine involving a new type of ignition for lighting hydrogen-peroxide/RP-1.
Outside of research, John was program manager for the Purdue Hybrid Rocket project. That group designed and hot-fire tested various hybrid rocket motors and flight vehicles. In June 2009, the team launched a hydrogen-peroxide hybrid rocket to 6,100 feet, receiving an AIAA Best Paper award for that work.
He was also instrumental for the successful flight of the experimental Aluminum/Ice (ALICE) motor co-sponsored by NASA and the Air Force. The first flight of the ALICE rocket received significant media attention with articles in mainstream media as well as engineering and aerospace-related publications.