Project Northstar is a variable impulse hybrid rocket engine under development for Saint Louis University Rocket Propulsion Lab’s use in sounding research rockets. Project Northstar is designed for seamless integration into a standard airframe and motor mount or legacy SLU RPL airframes, which ensures adherence to the International Rocketry and Engineering Challenge’s (IREC) standards. Northstar is an O-4200 classified hybrid engine that uses PMMA fuel and liquid nitrous oxidizer. An adjustable oxidizer flow system to enable real-time thrust control which provides precise altitude control, and also enhances the relative safety of the launch vehicle.