Castelion Announces $350 Million Series B

Castelion, a defense technology company focused on restoring America’s conventional deterrence, announced a $350 million Series B last week to accelerate large-scale production of hypersonic munitions.

The round was led by Altimeter and Lightspeed, with participation from Lavrock Ventures, Andreessen Horowitz, General Catalyst, First In, SVC (Space VC), Cantos, BlueYard Capital, Avenir, Champion Hill, and Interlagos. 

The funding positions Castelion to move from rapid prototyping into industrial-rate manufacturing.

Capital from the round will support integration of Castelion’s first hypersonic weapon, Blackbeard, with U.S. Army and Navy operational platforms, expansion of high-tempo flight testing in 2026, and construction of Project Ranger, the company’s large-scale production and final-assembly facility in New Mexico.

Project Ranger, located on a 1,000-acre solid rocket motor manufacturing campus, is designed to produce thousands of Blackbeard missiles per year and create hundreds of high-skilled manufacturing jobs. The facility anchors Castelion’s strategy of building hypersonic weapons at volumes and costs suitable for real-world deterrence, not boutique inventories.

In 2025 alone, Castelion conducted more than 20 development flight tests, validating internally manufactured solid rocket motors, seekers, flight computers, thermal protection systems, and mission software. The company’s approach compresses design-to-launch timelines from years to months by emphasizing low-cost, mass-producible architectures.

Leadership and investors emphasized that hypersonic capability only matters if it can be produced at scale. Castelion’s rapid testing cadence, vertically integrated manufacturing, and production-first design philosophy aim to close the U.S. hypersonic gap against peer adversaries while rebuilding depth in the American defense industrial base.

Image Credits: Castelion