This project involves the design, manufacturing, and testing of the Cal Poly Space System’s M-class 98mm hybrid rocket motor. The 20 inch-long motor utilizes hydroxylterminated polybutadiene as fuel with 600 psi liquid nitrous oxide as the oxidizer. Modeling and analysis was conducted on a 12 port self-impinging swirl injector and fuel manufacturing to improve performance. Several hot and cold flow tests were conducted to validate the analysis with measured performance values. Two successful test fires resulted in an average of 212 lbf of thrust for 6 seconds with an Isp of 160 seconds and an average thrust of 260 lbf of thrust for 6 seconds with an Isp of 200 seconds. Analytical models predicted a thrust of 225 lbf for 6 seconds with an Isp of 180 seconds and an initial oxidizer pressure of 600 psig.