Hermeus is a venture-backed defense aviation company reclaiming the lost art of rapid iterative prototyping to build the fastest aircraft in the world today. By prioritizing relentless hardware iteration, we deliver high-speed systems at the pace of the modern battlefield. We work with the Department of War to provide the high-speed capabilities our nation and its allies need to maintain a durable, asymmetric advantage. As a Development Engineer on the Propulsion team, you will be responsible for advancing engine hardware through rapid, test-driven iteration. You will operate at the intersection of hardware execution and data analysis, owning engine test campaigns and translating results into actionable engineering improvements.This role requires strong hands-on capability, analytical rigor, and the ability to move quickly between test operations, data interpretation, and hardware problem-solving. You will play a critical role in increasing engine development velocity and reliability.Responsibilities Own development engine test campaigns from planning through execution and post-test analysis Define, author, and refine engine test plans, procedures, and setpoints aligned with program objectives Support and make decisions during live test operations, including hot-fire and subsystem testing Identify, diagnose, and resolve test-related engine issues across hardware, instrumentation, and procedures Standardize and improve test data review, reduction, and reporting processes Develop Python-based tools for data processing, visualization, and automated analysis Translate test data into clear engineering insights, including performance characterization and root cause analysis Drive post-test reviews and ensure actionable outcomes are captured and executed Participate in hands-on engine build, integration, and test setup activities Author and maintain development engine work instructions, test procedures, and technical documentation Generate, track, and resolve engineering issues through ticketing systems Collaborate cross-functionally with design, manufacturing, avionics, and test teams to resolve system-level challenges Ensure proper sensor selection, instrumentation setup, and data integrity during test campaigns Contribute to continuous improvement of test infrastructure, tooling, and development processes Basic Qualifications Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, or a related discipline Hands-on experience with hardware build, integration, or test operations Experience developing or executing engineering test plans and procedures Proficiency in Python for data analysis and automation Strong understanding of sensors, instrumentation, and diagnostic techniques Preferred Qualifications Experience with liquid rocket engines or air-breathing propulsion systems Familiarity with high-speed data acquisition and telemetry systems Background in thermofluids, combustion, or turbomachinery Experience operating in fast-paced, iterative hardware development environments Demonstrated ownership of hardware or test systems through multiple development cycles U.S. EXPORT CONTROL COMPLIANCE STATUS The person hired will have access to information and items subject to U.S. export controls, and therefore, must either be a “U.S. person” as defined by 22 C.F.R. § 120.62 or otherwise eligible for deemed export licensing. US persons include U.S. citizens, U.S. nationals, lawful permanent residents (green card holders), and asylees and refugees with such status granted, not pending. EQUAL OPPORTUNITY Hermeus is an Equal Opportunity Employer. Employment decisions at Hermeus are based solely on merit, competence, and qualifications, without regard to 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. 91800 - 187450 USD a year The salary information provided is a general guideline only. Hermeus takes various factors into account, including, but not limited to, the position's scope and responsibilities, the candidate's professional background, education and training, essential skills, and market and business considerations, when presenting a job offer. Salary is only one part of our total compensation and benefits package. Hermeus offers competitive salary and equity, unlimited PTO policy, paid parental leave, potential for year-end bonuses, and more! 100% employer-paid health care 401k & Retirement Plans Unlimited PTO Weekly Paid Office Lunches End of Year Bonuses Fully stocked breakrooms Stock Options Paid Parental Leave