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 Mechanical Engineer specialized in thermal to own thermal design across Archimedes — managing kilowatt-class waste heat from a fiber laser system in a deployable, field-rugged package. Thermal is one of the harder problems in directed energy and a make-or-break domain for the platform. You'll work hands on from architecture through bench validation and field correlation.

What You'll Own:

• Thermal architecture across the laser source, laser head, and supporting subsystems
• Liquid cooling design including cold plates, manifolds, heat exchangers, and pumps
• Two-phase, heat pipe, or refrigerant systems where appropriate
• CFD modeling and steady-state and transient thermal analysis
• Thermal validation including instrumentation, test rigs, and correlation to model
• Trades between thermal performance, mass, power, and packaging across the system

What We're Looking For:

• 3 to 10+ years in mechanical or thermal engineering on high-power systems
• Strong CFD experience with Star-CCM+, Fluent, FloEFD, or equivalent
• Hands on liquid cooling design including cold plates and heat exchangers
• Track record building and instrumenting thermal test rigs and correlating model to bench
• Experience designing for ruggedized or field-deployable conditions

Where you probably come from: High-power laser companies, data center liquid cooling, EV battery thermal, aerospace thermal, or high-power RF or radar thermal programs.

We want to talk if: You've designed a thermal system that had to dissipate kilowatts in a constrained, deployable package. You can model it, build it, instrument it, and correlate it.

Not a fit if: You've only done HVAC or building thermal, your work is simulation-only with no bench validation, or you've only worked at chip-package scale.

Nice to Haves:

• Two-phase cooling system design
• Direct laser system thermal experience
• Field-deployable or ruggedized thermal experience
• EMI/EMC awareness for thermal hardware integration

Education:

BS or MS in Mechanical, Aerospace, or related engineering field. PhD welcome but not required.

How You Operate:

• Extreme bias for action. You'd rather build and instrument the rig tomorrow than model it for a month
• You characterize your own systems before the field does
• Comfortable with ambiguity and fast iteration in a startup environment
• Clear communicator across mechanical, electrical, optical, and software teams
• Self directed. You identify what needs to happen next and do it without being told

Why Join Aurelius Systems:

• Build more in 1 month than most engineers 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 equity
• United Health Care medical, dental, and vision coverage
• Flexible 18 days PTO plus 5 sick days
• Travel to field test events and range days
• Covered daily lunches and office snacks and drinks
• E-bike and scooter stipend up to $500
• Direct access to leadership and real ownership over your work

Export 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).