Sr. Mechanical Engineer, Thermal

Who We Are:Aurelius Systems is a VC backed defense tech startup building autonomous, edge deployed directed energy systems for counter-UAS. We build laser weapons to shoot down drones.We're a small team of engineers, former US military operators, and subject matter experts scaling America's directed energy dominance. The first cost effective, reliable and robust laser weapon system.Our namesake isn't an accident. Marcus Aurelius wrote about doing the work in front of you, every day, without excuses. Henry Ford didn't wait for permission to reinvent manufacturing.That's how we operate — small team, unreasonable output, no hiding behind the unachievable.In addition to our San Francisco lab, we’ve opened a Detroit manufacturing hub and we field test weekly on our own 400-acre private range.The Role and Your Impact:We need a Senior Mechanical Engineer with deep thermal expertise to own the thermal architecture of Archimedes, with direct focus on the turret and gimbal that carry the laser source. High-power directed energy systems live or die on thermal management. You'll design, simulate, and prove out the cooling solutions that keep our laser performing at multi-kilowatt power over sustained operation, inside a moving turret, in real-world environments.This is a thermal lead role. You set the thermal design philosophy. You build the simulation framework. You implement cooling loops, heat exchangers, and conduction paths that survive an outdoor environment, not just a lab. You partner directly with the laser, optics, electrical, and controls teams to manage thermal budget across the integrated system.What You'll Own:Thermal architecture of Archimedes end to end, with primary focus on the turret and gimbal subsystems that house the laser source.Cooling loop design and implementation including pumps, heat exchangers, cold plates, working fluid selection, and routing through rotating and translating joints.Thermal simulation in ANSYS, COMSOL, or equivalent. CFD where it accelerates the design decision, not where it justifies one.Thermal modeling across the optical chain, motor drives, power electronics, and ambient environment.Heat sink design, thermal interface material selection, and conduction path optimization for high-power-density components.Test fixture development and execution for thermal qualification including operational thermal cycling, soak testing, and steady-state characterization.Partnership with the optics team on thermal lensing, beam quality degradation, and stable beam path under thermal load.Materials selection for thermal performance across metals, ceramics, and composites DFM and supplier engagement for thermal components including custom heat exchangers, cold plates, and cooling system hardwareWhat We're Looking For:5 to 10+ years in mechanical engineering with primary focus on thermal design and implementationPractical implementation experience. You've spec'd pumps, sized heat exchangers, selected working fluids, and built systems that hit thermal targets on hardware Direct hands-on experience implementing cooling solutions for high-power systems.Strong simulation background in ANSYS Thermal, COMSOL, or equivalent. CFD experience is required for this role, not optionalDeep understanding of conduction, convection, radiation, two-phase cooling, and where each appliesHands-on test and validation experience including thermal cycling, IR imaging, thermocouple instrumentation, and steady-state characterizationExpert in CAD (SolidWorks, Creo, or similar)Nice to Haves:Familiarity with turret, gimbal, or rotating-joint hardware is a strong plus. The thermal problem on Archimedes lives inside a moving structure with rotating joints carrying coolant and electrical lines. You don't need to have designed gimbals before, but you need to be ready to work inside that constraint.Active security clearance or ability to obtain oneFamiliarity with MIL-STD-810, MIL-STD-461, and related qualification standardsEducation:BS or MS in Mechanical Engineering, Aerospace Engineering, or related field. What you've built matters more than where you went to school.How You Operate:Extreme bias for action. You'd rather build a prototype tomorrow than model it for a monthYou characterize your own systems before the field doesComfortable with ambiguity and fast iteration in a startup environmentYou debug from first principles, not intuition aloneClear communicator across mechanical, electrical, optical, controls, and software teamsSelf directed. You identify what needs to happen next and do it without being toldWhy Join Aurelius Systems:Build more in 1 month than most technicians build in 1 year. We field test weekly. Your work goes downrange, not into a filing cabinet.Career velocity is real. At ~10 engineers, there are no layers between you and impact.Work on a problem that actually matters. Small cheap drones are changing warfare. Our laser systems are the asymmetric answer — infinite magazine, near zero cost per shot, scalable to every base, border, facility, and truck.Join the densest defense startup ecosystem in the country. California is where the next generation of defense companies are being built.How We Work:Core hours are Monday through Friday, 9 to 6. When we're sprinting toward a demo or field test, the team ramps up — nights, weekends, whatever it takes to ship. When the sprint lands, we ramp down. We don't manufacture intensity for show.Benefits:Competitive salary and equityUnited Health Care medical, dental, and vision coverageFlexible 18 days PTO plus 5 sick daysTravel to field test events and range daysCovered daily lunches and office snacks and drinksE-bike and scooter stipend up to $500Direct access to leadership and real ownership over your workExport Control Notice:This role requires access to export-controlled information or items that require U.S. Person status. As defined by U.S. law, individuals who are any one of the following are considered to be a U.S. Person: (1) U.S. citizens, (2) legal permanent residents (a.k.a. green card holders), and (3) certain protected classes of asylees and refugees, as defined in 8 U.S.C. 1324b(a)(3).