Mechanical Engineer Fall 2026 Co-Op

Castelion Corporation•Torrance, CA

3d•Onsite

About The Position

Join Castelion 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. 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.

Requirements

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.
Strong academic record with relevant coursework in areas such as mechanical design, propulsion, power systems, or related fields
Hands-on experience through lab work, projects, or internships is a plus.
Passion for aerospace, defense technology, and innovative engineering solutions.
Excellent problem-solving, analytical, and communication skills.
Ability to work collaboratively in a fast-paced, team-oriented environment.
To conform to U.S. Government export regulations, the applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (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.

Nice To Haves

Experience with hardware design, testing, data acquisition, and analysis.
Familiarity with missile systems, defense technology, or aerospace components.
Strong interest in working in a startup environment with high-impact projects.

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.