About the role

We are looking for a Lead Integration & Test Engineer with 5+ years of experience to own the end-to-end integration and verification of hypersonic strike vehicles as Castelion prepares to deliver its first 50 Blackbeard units to the U.S. Navy. This is an incredibly cross-functional engineering role — you'll be embedded in the build process from day one, ensuring every subsystem is properly validated before handoff to the customer. You need to be someone with deep systems-level understanding, strong foresight to anticipate integration issues before they arise, and the ability to work across mechanical, electrical, and software domains. The ideal candidate comes from a high-complexity, high-stakes environment — think first-build programs, pilot builds, or new product development where engineering standards are non-negotiable. You'll also mentor a junior integration engineer and help build out the I&T function as Castelion scales production.

What will you be doing?

Leading vehicle-level integration activities — ensuring form, fit, and function across all subsystems (warheads, propulsion, avionics, structures) as units move through production
Developing and executing integration & test strategies that catch issues during the build process, not after — acting as the quality gatekeeper before customer delivery
Writing and running test automation scripts (Python, LabVIEW) for environmental testing including vibration, thermal, and vacuum chamber validation
Designing integration tooling and fixtures for safe handling and assembly of energetic and complex mechanical systems
Mentoring a junior integration & test engineer and building out the I&T team to support production scale-up across Torrance and Rio Rancho facilities

Castelion is a modern defense production company building long-range hypersonic strike systems to address a critical national security gap. Founded in 2021, Castelion was created in response to the recognized need for the United States to rapidly develop hypersonic capabilities to remain competitive with near-peer adversaries and deter future conflicts.

The company operates under the philosophy of "Peace through Deterrence" — building the weapons systems that ensure conflicts never need to happen. Castelion is one of the few companies in the hypersonics space that has moved beyond concepts to actual production deliverables, with government contracts across multiple branches of the military and a $23M+ Navy order for 50 units in calendar year 2027.

Backed by over $469M in funding from top-tier investors including Andreessen Horowitz, Lightspeed Venture Partners, and General Catalyst, Castelion is scaling rapidly. The company is building what it anticipates will become the preeminent hypersonics campus in the country — including a $150M, 1,000-acre solid rocket motor manufacturing facility in Rio Rancho, New Mexico, alongside its headquarters in Torrance, California.

Castelion's culture is defined by technical excellence, ownership, and velocity. Engineers own meaningful subsystems on the vehicle and are responsible for driving their success. The company follows a responsible engineering model inspired by SpaceX, where individuals choose the highest-value work and are empowered to cultivate resources and partnerships to deliver results. The engineering bar is exceptionally high — attracting elite talent who want to be surrounded by other elite talent.

Lead Integration & Test Engineer

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