Senior Propulsion Engineer; Rocket Motor Soft Goods

Senior Propulsion Engineer (Rocket Motor Soft Goods)

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts.

This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

We are seeking a Senior Propulsion Engineer to design and deliver rocket motor soft goods for Castelion's long-range hypersonic strike vehicles. This role is critical to ensuring reliable motor performance, structural integrity, and thermal protection through the design of liners, insulators, inhibitors, and related internal components. You will work hands-on with multidisciplinary engineering teams to design, analyze, build, and validate soft goods systems in a fast-paced, hardware-driven environment.

• Design and develop rocket motor soft goods, including liners, insulators, inhibitors, and internal thermal protection systems
• Lead the architecture and detailed design of soft goods systems to ensure compatibility with propellant, case materials, and motor operating conditions
• Perform thermal, chemical, and structural analyses to ensure performance and durability under high-temperature, high-pressure environments
• Develop and optimize material selections and formulations in collaboration with materials and manufacturing teams
• Define and manage bonding strategies between propellant, liner, insulation, and motor case to ensure robust adhesion and prevent debonding
• Work closely with propulsion, structures, and manufacturing teams to ensure seamless integration of soft goods with overall motor design
• Support material processing, fabrication, and quality control of soft goods components
• Plan and execute test campaigns, including subscale and full-scale motor testing, and analyze results to drive design improvements
• Conduct failure analysis and root cause investigations related to insulation performance, erosion, cracking, or debonding
• Mentor junior engineers and contribute to best practices in soft goods design and processing
• Partner closely with program leadership to make technical trades aligned with mission success

• Bachelor's, Master's, or PhD in Aerospace Engineering, Mechanical Engineering, Materials Science, or related field
• 5+ years of experience in rocket propulsion or high-temperature material systems, with focus on soft goods or internal motor components
• Strong background in insulation materials, liners, and bonding systems used in solid rocket motors
• Experience with thermal protection materials and behavior under high heat flux and pressure environments
• Familiarity with propellant compatibility, adhesion, and chemical interactions with soft goods materials
• Experience with material processing techniques for elastomers, ablatives, or composite insulation systems
• Proficiency in analysis and modeling tools (e.g., MATLAB, ANSYS, or equivalent)
• Experience with propulsion testing, data analysis, and failure investigation
• Strong problem-solving mindset, thriving in a fast-paced, hardware-rich, high test cadence environment

While this position does not currently require a U.S government-issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government–issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.