Mechanical Design Engineer

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.

Castelion is seeking a high-output Staff Mechanical Design Engineer with 8+ years of experience designing, analyzing, testing, and delivering flight hardware. This role is for a deeply technical engineer who can serve as a domain expert and technical leader while owning mission-critical hardware from concept through flight.

The Staff Mechanical Design Engineer will develop expertise in an area such as mechanisms, structures, avionics packaging, or other mechanical systems, and will set a high bar for technical excellence across the team. This person will be expected to solve complex engineering problems independently, make sound design and analysis trade-offs, and mentor engineers to grow their technical capabilities.

• Own Flight Hardware:
  Lead the design, analysis, build, integration, and test of critical flight hardware from concept through flight.
• Technical Excellence:
  Serve as a technical authority in a mechanical domain such as mechanisms, structures, or avionics packaging. Establish and maintain high standards for design, analysis, manufacturability, and flight readiness.
• Structural Analysis:
  Perform and/or lead structural analysis using first-principles engineering, FEA, statics, vibration, and modal analysis.
• Rapid Development:
  Drive high-cadence design iterations, incorporating test results and lessons learned into rapid hardware improvements.
• Hands-On Engineering:
  Work directly with technicians, manufacturing, suppliers, and test teams to troubleshoot hardware and drive problems to closure.
• Engineering Leadership:
  Mentor engineers through design reviews, technical problem-solving, and hands‑on coaching. Raise the technical capability and engineering standards of the broader team.
• Engineering Rigor:
  Improve CAD, analysis, documentation, hardware development, and design practices while maintaining speed and technical discipline.

• Bachelor's degree in Mechanical Engineering or related field.
• 8+ years of professional mechanical engineering experience.
• Demonstrated experience taking complex hardware from concept through design, analysis, manufacturing, integration, test, and operation.
• Deep expertise in at least one mechanical domain, such as mechanisms, structures, avionics packaging, or similar.
• Expert-level CAD and mechanical design skills, including GD&T, tolerance analysis, materials, and manufacturability.
• Strong understanding of structural mechanics, statics, vibration, and FEA.
• Experience designing high-performance hardware with constraints on mass, cost, schedule, reliability, and manufacturability.
• Strong hands-on problem-solving skills and experience working directly with hardware.

• Experience correlating analytical models with physical test data.
• Aerospace, hypersonic, launch vehicle, spacecraft, or other high-performance flight hardware experience.
• Experience establishing engineering standards or methodologies.
• Demonstrated ability to mentor and develop engineers technically.
• Experience working with composites, coatings, finishes, and advanced manufacturing processes.

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…