Senior Mechanical Design Engineer (RF Systems & Radomes)

About the role

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.

Senior Mechanical Design Engineer (RF Systems & Radomes) – design and deliver RF-critical structures and packaging for Castelion's long-range hypersonic strike vehicles. Focus on radome development and RF subsystem integration, ensuring structural integrity and thermal survivability while preserving RF performance. Work hands‑on with multidisciplinary engineering teams to design, analyze, build, and validate radomes and RF packaging solutions in a fast‑paced, hardware‑driven environment.

Responsibilities

• Design and develop RF-transparent structures, including radomes, windows, and associated support structures for high-speed flight vehicles
• Lead the architecture and detailed design of RF subsystem packaging, including mounting, alignment, and environmental protection of antennas, seekers, and electronics
• Perform structural and thermal analyses to ensure performance and reliability under extreme aerothermal, pressure, and dynamic environments
• Work closely with RF, avionics, materials, and thermal teams to ensure designs meet RF performance requirements (e.g., transmission, reflection, boresight error) while maintaining structural integrity
• Develop and analyze interfaces between radomes, TPS, and primary structure, including sealing, attachment, and thermal isolation strategies
• Conduct tolerance analysis and assess alignment sensitivity and deformation impacts on RF performance
• Support prototyping, assembly, and hardware bring-up, including troubleshooting and root cause analysis of structural and RF performance issues
• Define and execute qualification and environmental test plans, including thermal, vibration, and RF testing
• Optimize designs for mass, thermal performance, RF transparency, and manufacturability
• Mentor junior engineers and contribute to best practices in RF structure and packaging design
• Partner closely with program leadership to make technical trades aligned with mission success

Requirements

• Bachelor's, Master's, or PhD in Mechanical Engineering or related field
• 5+ years of experience in mechanical design for aerospace or high-performance systems
• Experience designing radomes, RF-transparent structures, or packaging for RF/antenna systems
• Familiarity with RF performance considerations such as dielectric properties, insertion loss, and boresight error
• Strong background in structural and thermal analysis for extreme environments
• Proficiency in CAD and analysis tools (e.g., NX, SolidWorks, ANSYS, or equivalent)
• Experience with tolerance stack-up, alignment, and precision assembly design
• Familiarity with materials used in RF applications (e.g., ceramics, composites, low-loss dielectrics) and high-temperature environments
• Experience with hardware build, test, and troubleshooting in a lab or flight hardware environment
• Strong problem‑solving mindset, thriving in a fast‑paced, hardware‑rich, high flight cadence environment
• Ability to obtain and maintain a U.S. government‑issued security clearance (U.S. citizenship required)

Benefits and Perks

• Meaningful long‑term equity for all full‑time employees
• Four (4) weeks of paid time off
• Ten (10) company‑paid holidays
• Comprehensive health benefits – 100% employee‑covered medical, strong dependent coverage, dental and vision plans
• Paid parental leave
• $100 monthly fitness stipend
• Onsite EV charging
• Catered meals, company‑covered food during high‑demand periods, fully stocked kitchen