Senior Development Test Engineer - Mechanisms

The Senior Development Test Engineer owns the planning, execution, and analysis of tests that turn designs into flight-ready mechanisms. This role sits at the center of engineering, manufacturing, and operations-translating requirements into real-world validation through benchtop, environmental, subsystem, and vehicle-level testing. You will design test stands and write automation software to enable rapid testing to drive iterative design.

This is a hands-on role for engineers who thrive in fast-paced, ambiguity-heavy environments and believe the fastest way to learn is to test real hardware.

Responsibilities

• Translate system and subsystem requirements into test objectives, acceptance criteria, and verification methods
• Own development and acceptance testing for flight mechanisms for Castelion’s hypersonic strike missiles
• Design and build complex test stands with integrated load actuators and instrumentation
• Develop automated test software for instrument control, test sequencing, data logging, and analysis; Python is preferred.
• Maintain rigorous configuration control, data management, and test documentation
• Improve test infrastructure, automation, and data quality to increase test cadence and learning velocity
• Support flight tests and rocket motor static fires as required

Test Plan/Schedule, Test Plan/Schedule, Testing, Analysis Skills, Test Design, Manufacturing Operations, Automation Systems, Requirements Management, Software Development, System Test, * Bachelor’s degree in Mechanical, Electrical, Aerospace, or related engineering field

• 5+ years of experience developing, integrating, or testing mechanical, electromechanical hardware
• Experience with test instrumentation and lab equipment (DAQs, oscilloscopes, power supplies, sensors)
• Experience with common sensors like load cells, pressure transducers, LVDTs, encoders
• Strong debugging, troubleshooting, and root-cause analysis skills
• Comfortable working across disciplines in high-ownership environments
• Willingness to support extended hours, weekends, travel, and on-site operations during critical test campaigns
• Comfortable working in fast-moving environments where hardware is the source of truth
• Environmental testing: vibration, thermal-vacuum, thermal cycling, shock

Preferred Skills and Experience

• Aerospace, automotive, defense or other high-reliability hardware testing
• Flight test, range operations, or hardware-in-the-loop (HIL) experience
• Familiarity with requirements verification, qualification evidence, and failure tracking
• Hands-on machining, wiring, soldering, or rapid prototyping experience

What We Value

• Hands-on rigor: deep understanding of systems through direct testing and failure analysis.
• Autonomy and ownership: you don’t wait for direction you seek out what needs to be tested and make it happen.
• High standards for reliability, data quality, and test repeatability.
• Systems-level thinking: understanding how actuator behavior affects broader vehicle performance.

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.