Castelion was founded to restore America’s ability to field advanced weapons at speed and scale. Inspired by the engineering urgency of the WWII and Apollo eras, we combine rapid iteration, vertical integration, and scalable manufacturing to deliver affordable, high-performance strike systems. Our mission: rebuild industrial agility to strengthen national security and outpace evolving threats.

About the Role:

Senior Propulsion Engineer (Rocket Motors)

We are seeking a Senior Propulsion Engineer to design, build, and test rocket motor systems for Castelion's long-range hypersonic strike vehicles. This role is critical to delivering reliable, high-performance propulsion across all mission phases. You will work hands-on with multidisciplinary engineering teams to develop solid rocket motors and associated hardware from concept through flight test in a fast-paced, hardware-driven environment.

Requirements

Bachelor's, Master's, or PhD in Aerospace Engineering, Mechanical Engineering, or related field
5+ years of experience in rocket propulsion design, analysis, and testing for aerospace or defense applications
Strong background in solid rocket motor design, including internal ballistics, grain design, and nozzle performance
Experience with propulsion testing, including static fire test setup, instrumentation, and data analysis
Familiarity with structural and thermal design considerations for high-temperature, high-pressure systems
Proficiency in analysis and modeling tools (e.g., MATLAB, ANSYS, or equivalent)
Experience with hardware build, integration, and troubleshooting in a lab or test environment
Strong problem-solving mindset, thriving in a fast-paced, hardware-rich, high test cadence environment

Benefits

Employee Equity: Meaningful equity for all full-time employees - share value has increased 150x in three years
Personal Time Off: Four (4) weeks of paid time off to unplug, reset, and come back sharp—velocity matters, burnout doesn't
Company Paid Holidays: Ten (10) company paid holidays
Medical: We offer plans at 100% employee covered and 80% of dependent coverage
Dental & Vision: We cover 90% employees and 80% for dependents to ensure you and your family have access to quality preventive and ongoing care
FSA/HSA: To support long-term health and financial resilience, we offer FSA and HSA options that allow employees to set aside pre-tax dollars for eligible medical and dependent care expenses
Retirement: 401k plan offered to support long term financial growth along side high-impact, high-velocity work
Paid Parental Leave: We support growing families with meaningful time to bond and recover. Birthing parents are eligible for up to 10 weeks of paid leave, while non-birthing parents may take up to 4 weeks of paid leave. This time can be used for pre-natal care, pregnancy, childbirth, and related medical needs—ensuring every parent has the support they need during this important life moment.8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees
Meals & Catering: Frequently catered lunches and team meals, plus company-covered meals when extra time or effort is required
Snacks & Beverages: Fully stocked kitchen with unlimited snacks and drinks to keep you fueled throughout the day
Performance & Fitness: $100 monthly fitness stipend to support peak performance and health, both inside and outside of work
EV Charging: Onsite electric vehicle charging available for employees

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