Mechanical Engineer Intern (Winter/Spring 2027)

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.

Winter/Spring 2027 - Mechanical Engineering Internship Co-Op

Join us for a dynamic, hands-on experience developing next-generation missile systems. As an intern, you'll contribute directly to the design, testing, and integration of advanced defense technologies all within a fast-paced, collaborative startup environment where your work has immediate impact.

Key Responsibilities:

• Assist in the design, analysis, and testing of components for missile subsystems, including propulsion, guidance systems, power electronics, and more.

• Support engineering teams with simulations, modeling, and prototyping of critical hardware components.

• Conduct research and development tasks, gathering and analyzing data to inform design decisions.

• Participate in system integration efforts, helping to assemble and test subsystems in real-world test environments.

• Collaborate cross-functionally with engineering, manufacturing, and test teams to ensure project success.

• Document design processes, test results, and project progress, contributing to the continuous improvement of our systems.

• Attend technical reviews, design meetings, and team briefings to stay engaged with project developments and learn from industry experts.

Learning Opportunities:

• Gain hands-on experience in aerospace engineering, working on cutting-edge hypersonic missile systems.

• Develop your technical skills by working with high-performance teams and state-of-the-art tools.

• Learn about the full lifecycle of missile development, from design and prototyping to testing and final integration.

• Receive mentorship from experienced engineers and leaders in the aerospace and defense industry.

• Be a part of a fast-paced startup culture where innovation, teamwork, and rapid development are at the forefront.

Qualifications:

• Currently pursuing a Bachelor's or Master's degree in Mechanical Engineering, Aerospace Engineering, or a related field.

• Rising junior, senior, or graduate-level student preferred.