About Castelion

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We're designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.

Mechanical Engineer

Castelion is seeking a hands-on, high-agency Mechanical Engineer excited to take ownership of real flight hardware and grow alongside a fast-moving team. You will work on the design, fabrication, and integration of critical flight structures and mechanisms across Castelion's hypersonic vehicles. This role is ideal for someone who thrives in fast-paced environments, learns quickly, and wants to see their work go from concept to flight in weeks-not years. You'll be empowered to take on meaningful responsibilities immediately. This is a rare opportunity to grow as a full-stack engineer while working on hardware that matters.

Responsibilities

• Design and Develop Flight Hardware: Support the design, analysis, and build of mission-critical systems including composite tanks, separation mechanisms, and actuators. You'll contribute to CAD models, run basic analysis, and work with technicians and leads to integrate and test hardware.
• Rapid Iteration and Prototyping: Contribute to four-week subsystem prototype cycles. Participate in design reviews, integrate test feedback, and help drive continuous improvement based on real-world data.
• Get Hands-On and Learn Fast: Work closely with leads and technicians during builds. Learn how to write travelers, build notes, and quality documentation. Gain exposure to the full product lifecycle in a highly accelerated environment.

Basic Qualifications

• Educational Background : Bachelor's degree in Mechanical Engineering with 2+ years of professional ME experience, preferably in aerospace, automotive, or hardware-focused industries.
• Technical Skills : CAD design of mechanical components (e.g., SolidWorks, NX, or similar); understanding of statics, dynamics, and thermal principles
• Ownership Mentality : Eager to take on responsibility, contribute in a hands-on environment, and learn from experience
• Attention to Detail : Thoughtful about part numbers, materials, tolerances, and documentation-even when moving quickly

Leadership Qualities

• Bias to Action and Creative Problem Solving. Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support.
• High Commitment, High Initiative . A successful candidate will have a genuine passion for Castelion's mission and consistently look for ways to contribute to the company's technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity.
• Clear Communicator. Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.

ITAR Requirements

• To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

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.

All employees are granted long-term stock incentives as part of their employment at Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers four weeks of paid time off per year.