Castelion raises $350M to scale hypersonic missiles
Hypersonic weapons startup Castelion is accelerating its mission to reshape the U.S. defense landscape. The company has secured a massive $350 million Series B funding round, led by Lightspeed Venture Partners and Altimeter Capital, according to documents viewed by TechCrunch. This latest funding values Castelion in the billions and comes just months after its $100 million Series A in January, which Lightspeed also led.
Founded by former SpaceX executives, Castelion is bringing Silicon Valley-style speed and agility to a traditionally slow-moving defense sector. The startup’s ambition: to mass-produce hypersonic missile systems—critical weapons that travel at speeds exceeding Mach 5—faster and cheaper than established aerospace giants.
Taking Aim at a Critical National Security Gap
Hypersonic weapons have become a strategic focus for the U.S. military, especially as China has demonstrated rapid advancements in the technology. Despite the Pentagon’s vast budget, American military leaders have voiced concern that the U.S. is falling behind in this race.
Castelion is pitching itself as the agile disruptor capable of closing that gap. Adopting a rapid development approach reminiscent of SpaceX—fast prototyping, frequent testing, and vertical integration—the company aims to drastically cut costs and development times.
Since emerging from stealth mode in late 2023, Castelion has already gained traction. It has won grants and awards from key Department of Defense (DoD) offices such as the Air Force Research Laboratory and the Naval Air Systems Command. In March, the company successfully tested its hypersonic vehicle in the Mojave Desert, a key milestone on its path to proving scalable, low-cost hypersonic capabilities.
Government Backing Builds Momentum
Castelion’s momentum was further underscored by its inclusion in the U.S. Army’s fiscal year 2026 budget request. The Army has allocated $25 million under Project HX3 to support the development and testing of Castelion’s “Blackbeard Ground Launch (GL),” an affordable, mass-produced hypersonic missile. According to budget documents, Blackbeard GL will offer about 80% of the capability of the Army's more expensive long-range hypersonic weapons, reflecting a strategic trade-off: lower cost for slightly reduced performance.
The Army contract outlines a two-phase approach. First, Castelion will deliver a prototype and conduct a proof-of-concept demonstration in early 2026. If successful, the company will proceed to build and deliver 10 prototype missiles in 2027, designed to launch from existing platforms such as the High Mobility Artillery Rocket System (HIMARS). Future iterations may integrate with autonomous launcher systems, extending the weapon's battlefield flexibility.
Eyes on a Lucrative Future
While Castelion’s current DoD contracts are relatively modest, the company is positioning itself for much larger opportunities. If the Army's field tests prove successful, Castelion could win a major production contract, potentially starting deliveries of Blackbeard missiles by 2028.
Such success would position Castelion as a serious challenger to the defense industry’s heavyweights—Lockheed Martin, Raytheon, and Northrop Grumman—who have long dominated the hypersonic space. With billions of dollars in potential contracts on the horizon, these incumbents may soon face unexpected competition from a startup determined to rewrite the rules of military procurement.
Castelion declined to comment on its latest funding or government contracts. But with its war chest growing and critical tests ahead, the company’s next moves could shape the future of American hypersonic weapons development.
