Senior Thermal Engineer

Why Castelion, Why Now 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. Senior Thermal Engineer As a Senior Thermal Engineer at Castelion, you will own the thermal engineering methodology across our missile systems. You will define thermal architectures, develop high-fidelity thermal models, and use first-principles analysis, simulation, and hardware testing to ensure our vehicles perform reliably in some of the most demanding thermal environments imaginable. You'll work across aerodynamics, structures, electrical, propulsion, systems, manufacturing, and test engineering to develop integrated thermal solutions from concept through flight. Your work will span transient mission analysis, electronic unit thermal management, specialized ground testing, and flight-test instrumentation and data analysis. This role is ideal for an engineer who enjoys moving fluidly between analytical models, real hardware, and flight data—and who wants to directly influence vehicle architecture and design decisions from day one. Responsibilities • Thermal design and analysis of unmanned air vehicles at conceptual, preliminary, and detailed design maturities • Define thermal system architectures and material selection strategies for vehicles operating in demanding flight environments • Thermal analysis of flight vehicles using standard thermal analysis codes and engineering/hand methods • Transient thermal analysis for time-varying mission profiles • Ground test planning, execution, and analysis in specialized thermal test facilities • Flight test planning, execution, and post-flight thermal data analysis • Use first principles and MATLAB/Python models to inform design decisions • Collaborate with aerodynamics, structures, electrical, and systems engineers on integrated solutions • Present thermal status at formal reviews internally and with customers • Prepare formal documentation (specifications, test procedures, technical reports) Basic Qualifications • BS or higher degree in Aerospace Engineering, Mechanical Engineering, or Applied Physics • In-depth understanding of heat transfer, fluid dynamics, and high-temperature environments • 5+ years of experience in aerospace thermal engineering on rocket, spacecraft, aircraft, or missile programs • Experience with electronic unit thermal analysis and control to component junctions • Ground testing experience with thermal instrumentation and data acquisition • Strong programming skills in MATLAB, Python, or similar for tool development • Experience preparing formal documentation • CAD experience with SolidWorks or Siemens NX • Ability to obtain and hold a U.S. security clearance Preferred Skills and Experience • MS or higher degree in Aerospace Engineering, Mechanical Engineering, or Applied Physics with focus on heat transfer and fluid dynamics • Experience with material ablation response modeling in extreme thermal environments • Knowledge of material degradation and surface phenomena under demanding conditions • Experience with specialized thermal ground test facilities • Flight test experience including instrumentation design and post-flight analysis • Experience with Thermal Desktop/SINDA • Experience with manufacturing and assembly of thermal systems • Active U.S. security clearance Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. Other Duties 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. Additional Eligibility Requirements 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 requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.