Propulsion Engineer

About Poseidon Aerospace:

Poseidon Aerospace is reimagining how the world moves goods. We build and operate full-size autonomous cargo aircraft;
Heron, a seaplane, and Egret, a STOL aircraft; each capable of carrying two tons of payload over a thousand nautical miles. From remote communities to contested logistics operations, our platforms unlock a new cost curve for air freight, making it faster, cheaper, and accessible anywhere it's needed. Headquartered in San Francisco with offices in Washington, DC and Maine, we are a small team building something consequential.

As a Propulsion Engineer at Poseidon Aerospace, you will lead the propulsion team’s development from initial assembly and bring-up to a fully calibrated, instrumented power plant ready for flight. This is a hands-on role centered on engine assembly, design, tuning, and qualification via testing. You will run engines on the test stand, develop test procedures, prove they meet performance and durability targets, and collaborate cross-functionally to iterate and improve on the propulsion system.

If you have an interest in aviation, working hands-on in a test environment, motorsports or high performance engine tuning experience, and have strong instincts running an engine test cell, we are looking for you to join Poseidon.

• Calibrate the engine across the full aviation operating envelope: fueling, ignition, idle stability, transient response, knock, and closed-loop strategy on a standalone ECU, with the propeller governor tuned to performance and reliability targets.

• Run the engine test program on an instrumented test stand: break-in, bring-up, performance mapping, and endurance/qualification runs that prove each engine flight-ready.

• Bring up the integrated engine from assembled hardware through verification: outfit assemblies, prepare systems, diagnose faults, and close out anomalies.

• Operate test instrumentation and DAQ: Specify and collect required data to drive propulsion system improvements and validation in a safe and traceable manner.

• Translate & Present findings: distill, document, and present data to validate requirements, limits, and drive design changes. Work closely with other teams to refine and improve propulsion systems.

• Refine & develop the break-in, operating, inspection, and maintenance procedures: document and collect the procedures that carry the propulsion systems through test stand runs, ground runs, and flight tests.

• Applied tuning of standalone/aftermarket ECUs: fuel and ignition mapping, idle and transient control, drive-by-wire, knock, and sensor/DTC strategy.

• Strong conceptual and hands-on knowledge of 4-stroke piston engines

• Engine test-stand or dyno experience: experience building or running an instrumented cell, including thrust/torque measurement, cooling and oil-system instrumentation, and DAQ.

• Working knowledge of aircraft propeller and constant-speed governor systems.

• Sharp diagnostic, setup, and troubleshooting skills.

• Familiarity with controlled assembly and maintenance standards: FOD prevention, tool management, and shop safety.

• Hands-on experience tuning, calibrating, and bringing up EFI piston engine systems: aviation, motor sport, engine-swap, or standalone-ECU backgrounds are strongly relevant.

• Experience qualifying or validating engines on a test cell, dyno, or test stand, and ideally through ground and flight testing.

• Practical knowledge of aviation and automotive fuels (AvGas, MoGas) and their effect on calibration.

• Comfortable working at the bench and on the aircraft, with strong, self-directed troubleshooting instincts.

• Strong collaboration skills to communicate verification findings and design feedback clearly across disciplines.

• Competitive salary and meaningful early-stage equity

• Relocation support if applicable

• Low-ego, collaborative workplace culture

• 6% retirement matching

• Unlimited PTO

• Free lunches, snacks, and a stocked fridge at our offices

• AI tools and subscriptions

Even if you don’t meet every qualification listed, we encourage you to apply. At Poseidon Aerospace, we value diverse perspectives and are always looking for talented individuals with unconventional backgrounds.