Senior Mechanisms Engineer (TVC Actuation)

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 and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts.

This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

Senior Mechanisms Engineer (TVC Actuation)

We are seeking a Senior Mechanisms Engineer to design and deliver thrust vector control (TVC) actuation systems for Castelion's long-range hypersonic strike vehicles. This role is critical to enabling precise, high-bandwidth thrust vectoring under extreme dynamic and thermal environments. You will work hands-on with multidisciplinary engineering teams to design, analyze, build, and validate TVC actuators and associated mechanisms in a fast-paced, hardware-driven environment.

Responsibilities

• Design and develop TVC actuation systems, including actuators, linkages, mounts, and load paths for high-performance propulsion systems

• Lead the architecture and detailed design of electromechanical actuator (EMA) systems, including gear trains, bearings, and structural components

• Perform analysis of loads, stiffness, backlash, bandwidth, and dynamic response to ensure precise and stable thrust vectoring performance

• Work closely with propulsion, control electronics, GNC, and structures teams to ensure seamless integration of TVC systems with vehicle architecture

• Conduct tolerance analysis, lubrication strategy development, and life/reliability assessments for high-duty-cycle, high-load systems

• Support prototyping, assembly, and hardware bring-up, including troubleshooting and root cause analysis of actuator and mechanism performance issues

• Define and execute qualification and environmental test plans, including vibration, thermal, and shock testing

• Optimize designs for mass, stiffness, thermal robustness, reliability, and manufacturability

• Mentor junior engineers and contribute to best practices in actuator and mechanism design

• Partner closely with program leadership to make technical trades aligned with mission success Basic Qualifications

• Bachelor's, Master's, or PhD in Mechanical Engineering or related field

• 5+ years of experience in mechanism and actuator design for aerospace or high-performance dynamic systems

• Strong background in electromechanical actuators (EMAs), including motor-driven systems, gear reduction, and torque transmission

• Experience designing high-load, high-bandwidth actuation systems such as TVC, control surface actuation, or similar applications

• Familiarity with motor selection (e.g., BLDC), position sensing (encoders/resolvers), and actuator feedback integration

• Proficiency in CAD and analysis tools (e.g., NX, SolidWorks, ANSYS, or equivalent)

• Experience with structural analysis, fatigue/life assessment, and tolerance stack-up analysis

• Familiarity with high-temperature materials, lubrication strategies, and operation in extreme environments

• Experience with hardware build, test, and troubleshooting in a lab or flight hardware environment

• Strong problem-solving mindset, thriving in a fast-paced, hardware-rich, high flight cadence environment 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.

Benefits And Perks

All full-time employees are granted meaningful long-term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company-paid holidays, and comprehensive health benefits - including 100% employee-covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company-covered food during high-demand periods, and a fully stocked kitchen to stay fueled throughout the day.

While this position does not currently require a U.S government-issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government–issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance.

Affirmative Action/EEO Statement

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.