Principal Fluid Systems Engineer

The Fluid Systems team at Firefly Aerospace is responsible for all fluid subsystems across our launch vehicles and spacecraft, including our Blue Ghost Lunar Lander and Eclipse Launch Vehicle. As a Principal Propulsion Engineer, you’ll own the design, development, integration, test, and qualification of flight fluid systems. Working closely with engineering, manufacturing, and integration teams to iterate, answer questions, and close feedback loops.

This role blends deep technical ownership with cross-functional collaboration, serving as both an individual contributor and a technical mentor. The ideal candidate thrives in fast-paced, hardware-rich environments, embracing new challenges with grit, creativity, and accountability. We’re looking for engineers who are excited to roll up their sleeves and help define the future of space transportation.

RESPONSIBILITIES

Own and lead the full lifecycle development of flight fluid systemsfrom concept through launch and operation.

Develop architectures that improve reliability, simplify manufacturing, and reduce cost and schedule risk.

Define system requirements and interface definitions for propulsion, pressurization, venting, purging, fill/drain, and other fluidic subsystems.

Execute detailed designs using CAD and analytical tools, and coordinate closely with thermal, structural, systems, and integration teams.

Oversee qualification and acceptance test campaigns, including procedure development, test execution, and data review.

Lead technical risk trades, anomaly investigations, and corrective actions across engineering and production.

Mentor early-career engineers and provide technical reviews of hardware designs, analysis, and test plans.

Serve as the discipline owner in program architecture discussions and influence long-term roadmap for in-space servicing and reusability.

Bachelor’s degree in Mechanical, Aerospace Engineering, or a related field.

10+ years of experience in aerospace fluid systems or propulsion.

Proven ownership of a subsystem or major fluid component through design, build, and test.

Strong technical foundation in pressurized systems, cryogenics, high-pressure gas, and propellant feed design.

Proficiency in CAD, P&ID creation, and familiarity with ASME Y14.5 and aerospace standards.

Experience conducting system-level analysis, risk trades, and root cause investigations.

Excellent communication and collaboration skills across engineering and production teams.

Desired

Advanced degree (MS or PhD) in engineering discipline.

Demonstrated hands-on experience with hardware; including fluid test hardware and instrumentation

Familiarity with in-space propulsion, NASA standards, and range safety (91-710)

Experience with analytical tools such as GFSSP, Python, REFPROP, or thermal/fluid modeling.

Experience working with hypergolic bi-propellants

Understanding of propulsion engine cycles and integration with fluid systems.

History of developing flexible solutions with partially defined requirements and changing criteria

Ability to present technical content to internal and external review boards.

Firefly Aerospace is a space and defense technology company on a mission to reliably and repeatedly launch, land, and operate space systems from Earth to the Moon and beyond. As the partner of choice for critical space missions, Firefly is the first commercial company to launch a satellite to orbit with 24-hour notice and the first company to achieve a successful Moon landing. Headquartered in north Austin, Texas, Firefly is looking for passionate, hardworking innovators to join our team and help fuel our successful trajectory into space.