In spring 2023, a course split into two teams to see who could design, build and test the best rocket engine for less than $1,500. Carson Slabaugh, the Paula Feuer Associate Professor of Aeronautics and Astronautics, called for a methane-oxygen engine capable of a steady 300 lbf of thrust for two seconds, and two hot fires.

“Cost overruns kill many programs and always leads to delays. Cost has significant effects on design decisions and, in many cases such as this, force engineers to get creative,” Slabaugh says.

The teams, made up of graduate and undergraduate students, set up and ran the tests themselves at Zucrow Labs.

Team SpaceY designed a single-element shear-coaxial injector and an innovative graphite nozzle to handle the heat, fabricating two copies for $1196.43. Thrust was just shy of target, producing an average 294 lbf on the best test.

Team Frugal Fire designed a multi-element, impinging injector and used fuel film cooling on the nozzle. To reduce cost, the team machined the injector plate themselves and used brass and carbon steel materials. Total cost: just $652.38. Their output, 307 lbf, was impressive, but fuel film cooling wasn’t enough: The nozzle melted down during its first run, leaving no time for a second test.

Team SpaceY was declared the winner on spec, but Frugal Fire’s experience was also an opportunity for rocket forensics. It led to in-depth discussions with Slabaugh on combustion instabilities — a lesson they wouldn’t have gotten with a successful test.

“It was a formative experience,” said Christina Huynh of the SpaceY team. “This class is why I came to Purdue.”