Senior Propulsion Engineer Torrance, CA Mechanical Engineering

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability.

This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function.

The Propulsion Engineer plays a critical role at Castelion, owning the design of solid rocket motor primary and secondary structures as well as key propulsion components. This position is central to our ability to deliver at speed and scale, with a strong emphasis on driving technically sound designs that meet aggressive schedule, affordability, and production goals.

• Translate project objectives into cost-effective designs that can be produced at scale – the Castelion way.
• Spearhead the creation of innovative solid rocket motor designs, demonstrating autonomy even with limited expert guidance.
• Actively engage in the assembly, testing, and troubleshooting of prototypes and production builds, providing expert guidance as necessary.
• Use our rapid iteration cycles to validate product performance and facilitate necessary design adjustments.
• Produce, evaluate, and authorize CAD models and drawings, adhering to internal standards and ASME Y14.5-2009 guidelines.
• Provide thorough assessments and resolutions for any discrepancies in hardware, including supporting analyses when required.
• Collaborate with supply chain to ensure seamless support and adapt designs to mitigate availability risks and time delays.

• Bachelor's or advanced degree in aerospace engineering, manufacturing engineering, materials engineering, mechanical engineering or physics.
• 2+ years of mechanical or fluids design, analysis, or build experience (student project team, university rocketry club and internship experience counts).
• Effective communication skills are crucial for collaborating with cross-functional teams, presenting design concepts, and documenting work.

• Proficient in test methods/setups, with the ability to conduct trade studies using engineering fundamentals to make informed recommendations, even with limited information.
• Extensive experience working with aerospace materials (including metals, plastics, and composites) and a solid understanding of spacecraft and/or launch vehicle propulsion systems and fluid components.
• Skilled in CAD software (NX 8.5 or similar packages like PTC Creo, CATIA) with expertise in geometric dimensioning and tolerancing (GD&T) per ASME Y14.5-1994.
• Relevant experience with rocket motors, solid propulsion elements, and structural interfaces, including knowledge of insensitive munitions protocols and practices.
• Hold a master's degree or PhD in a technical discipline such as mechanical or aerospace engineering.
• Hands-on experience supporting rapid product development, including designing hardware for high-rate production in alternative non-aerospace domains.
• Currently hold an active DoD Secret Security Clearance or higher.

• Willing and able to work extended hours and/or weekends with minimal notification to meet critical deadlines leading up to major milestones.
• Able to travel up to 30% on an ongoing basis

Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details.

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice.

This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements.

You will be notified if and when such…