Senior Fluid Systems Engineer

At Relativity Space, we’re building rockets to serve today’s needs and tomorrow’s breakthroughs. Our Terran R vehicle will deliver customer payloads to orbit, meeting the growing demand for launch capacity. But that’s just the start. Achieving commercial success with Terran R will unlock new opportunities to advance science, exploration, and innovation, pioneering progress that reaches beyond the known. Joining Relativity means becoming part of something where autonomy, ownership, and impact exist at every level. Here, you're not just executing tasks; you're solving problems that haven’t been solved before, helping develop a rocket, a factory, and a business from the ground up. Whether you’re in propulsion, manufacturing, software, avionics, or a corporate function, you’ll collaborate across teams, shape decisions, and see your work come to life in record time. Relativity is a place where creativity and technical rigor go hand in hand, and your voice will help define the stories we’re writing together. Now is a unique moment in time where it’s early enough to leave your mark on the product, the process, and the culture, but far enough along that Terran R is tangible and picking up momentum. The most meaningful work of your career is waiting. Join us. About the Team: The Stage Fluids team designs and delivers the propellant, pressurant, pneumatics, and other fluid systems that turn structures into functioning rockets. The team has full ownership across design, production, test, and flight, maintaining a holistic view of Terran R, focused not on isolated parts but integrated functionality. Working on-site at the factory means you’re never far from the hardware, enabling rapid iteration and tight feedback loops across design and manufacturing. You won’t just be handed requirements: you’ll be expected to ask the right questions, collaborate with partners across the company, and ultimately find the best solutions for Terran R. About the Role: In order to be successful in this role, you should be someone who thrives in ambiguity and is able to lead their own projects into completion. A high degree of drive and autonomy is required. You must be flexible to changes in strategic direction and willing to push your understanding and intuition to ensure we as a company are producing the best possible product. You will be directly responsible for mission-critical systems and processes as a technical authority for one or multiple fluid systems and/or processes on the launch vehicle. Along with these high expectations comes the opportunity to have a significant influence on a fast-growing startup company and to oversee rapid progress in an environment that encourages growth and risk. In this role, you will be responsible for the design and analysis of the fluid systems that ensure reliable and efficient operation of Terran R vehicles. Specific responsibilities will include: Conducting trade studies to produce architectures and designs that satisfy system requirements Sizing at the system and component level Conducting fluid and thermal analyses, including system performance prediction and characterization using a variety of analytical methods (1D steady-state, transient, fluid networks, etc.) Creating tools to enhance our team’s analysis capabilities and streamline workflow Participating in design and manufacturing reviews Owning and leading test campaigns to validate system design and performance Anchoring models with data from test and launch About You: Bachelor’s degree (Mechanical Engineering or relevant) 5+ years of experience working with fluids systems Experience applying engineering fundamentals in system design, thermodynamics, fluid dynamics, and heat transfer Experience with one or more fluid or thermal modeling tools for internal compressible and incompressible analysis Experience with programming languages such as Matlab, Python, or C++ Nice to haves, but not required: Experience with launch vehicles and s ... (truncated, view full listing at source)