Castelion Secures $350 Million Series B to Scale Hypersonic Weapons Production
Castelion, the U.S. defense technology startup focused on affordable, mass‑produced hypersonic weapons, has confirmed a major influx of capital with its $350 million Series B funding round, underscoring growing investor confidence in its ability to scale production of advanced strike systems. The Torrance, California‑based company is accelerating its mission to address what many defense analysts describe as a critical capability gap in hypersonic deterrence.
The Series B round was co‑led by two prominent venture firms, with significant participation from a broad group of strategic investors. At the forefront of the investment were Altimeter Capital and Lightspeed Venture Partners, marking a major endorsement of Castelion’s rapid‑production approach. Other participants included Lavrock Ventures, Andreessen Horowitz, General Catalyst, First In Capital, Space VC, Cantos Ventures, BlueYard Capital, Avenir Growth Capital, Champion Hill Ventures, and Interlagos Capital. This constellation of investors reflects a mix of traditional venture capital backing and specialized firms betting on next‑generation defense manufacturing.
The hefty Series B follows an earlier $100 million funding effort in early 2025 that comprised a $70 million Series A equity round led by Lightspeed Venture Partners with participation from many of the same investors, alongside $30 million in venture debt from Silicon Valley Bank. That earlier round helped the company accelerate prototype testing and expand manufacturing capabilities for its first hypersonic weapon, known as Blackbeard.
Founded in late 2022 by former SpaceX engineers, Castelion has rapidly carved out a niche in the hypersonic weapons space by adopting rapid iteration and vertically integrated manufacturing techniques similar to those pioneered in the commercial space sector. The startup’s focus on compressing traditional defense production timelines — from years to months — has resonated with investors and defense partners alike.
According to the company, the new capital will be instrumental in advancing key technical and manufacturing milestones. A significant portion of the funding is earmarked for the buildout of Project Ranger, a sprawling 1,000‑acre solid rocket motor manufacturing campus in Sandoval County, New Mexico, designed to enable high‑volume production of hypersonic systems and create hundreds of skilled jobs in the region. Additional investments will support continued integration of Blackbeard with U.S. Army and Navy platforms, as well as expanded testing activity throughout 2026.
“Blackbeard helps close America’s hypersonic capability gap against China and Russia,” Castelion CEO and co‑founder Bryon Hargis said in announcing the funding. He emphasized that the infusion of capital would allow the company to “build fast, test often, and produce at volumes that matter in the real world.”
Investor sentiment reflects a belief that Castelion’s approach could reshape the economics of defense manufacturing. Erik Kriessmann, partner at Altimeter Capital, highlighted the team’s achievements in moving from concept to repeated flight tests in a relatively short period, while partners at Lightspeed and other firms pointed to the broader strategic importance of developing scalable hypersonic capability.
The company’s progress has been accompanied by broader interest from the U.S. Department of Defense, including integration contracts and budgetary support for hypersonic development initiatives. With the substantial backing of its latest funding round, Castelion is positioned to expand its workforce, advance manufacturing infrastructure, and potentially influence the direction of U.S. hypersonic deterrent strategy for years to come.
