A contract the U.S. Navy recently awarded to defense startup Castelion may point to its pursuit of a new, lower-cost, air-launched hypersonic strike weapon. The service has something of a gap to fill now after halting plans for an air-launched, air-breathing hypersonic anti-ship cruise missile roughly a year ago, due to cost and industrial base factors. A version of Castelion’s Blackbeard hypersonic missile could also find its way onto Navy ships and submarines, as well as ground-based launchers.
Last Friday, Castelion announced that it had received contracts from the Navy, as well as the U.S. Army, for “integration” of Blackbeard onto unspecified “operational platforms.” TWZ has reached out to the Navy for more information. The Army has already made clear it is interested in employing Blackbeard in a ground-launched mode, as you can read more about here.
“Under these agreements, Castelion will work with both services to integrate the hypersonic Blackbeard weapon system onto operational platforms and demonstrate its capabilities in live-fire tests – advancing the Department of War’s effort to evaluate and accelerate new, cost-effective strike capabilities for conventional deterrence,” according to a company press release. “Blackbeard is Castelion’s first long-range, hypersonic strike weapon, designed for mass production and rapid fielding once integration and testing are complete. The system leverages vertically integrated propulsion and guidance subsystems to achieve performance at a fraction of the cost of legacy weapons – supporting the Department’s objective of building credible, non-nuclear deterrent capacity at scale.”
Many questions remain about the expected final design and capabilities of the Blackbeard missile, including whether or not it will feature some form of air-breathing propulsion. The full “weapon system” could also incorporate multiple designs. Castelion has already conducted numerous live-fire launches using different test articles.
The designs seen in testing to date “are representative of the low-cost internally developed test vehicles we use to enable rapid subsystem design iteration and to ground our performance models in real-world test data,” Castelion told TWZ back in June. “Castelion’s approach to development focuses on getting into hardware-in-the-loop and flight testing early in development to support learning cycles across design, production, and test. As such, flight vehicles shown on social media are not representative nor intended to be representative of our final weapon systems.”
As TWZ has noted in the past, the term “hypersonic missile” typically refers to weapons designed for sustained hypersonic speed across a relatively shallow and even maneuvering trajectory. This can include designs that use a ballistic missile-like booster to loft an unpowered glide vehicle to a desired velocity and altitude before releasing it toward its target, as well as air-breathing cruise missiles capable of traveling at hypersonic speeds. Hypersonic speed is generally defined as anything above Mach 5, which larger ballistic missiles do reach in the course of their flights.
The testing that Castelion has disclosed so far has also been centered on the employment of Blackbeard in the ground-launched mode, which is fully in line with what is known about the Army’s plans for the weapon. The Navy could have a similar eye toward surface (or sub-surface) launch modes from ships, submarines, or even launchers on the ground.
At the same time, there are indications that the Navy is pursuing Blackbeard, at least in part, as an air-launched weapon. In February 2024, Castelion received a contract from the Office of Naval Research (ONR), valued at just under $3 million, to “perform an initial trade study to identify cost, schedule, and performance estimates of producing an air-launched anti-surface weapon and shipping system not to exceed 212″ in length with an on-aircraft weight limit of 2,750 lbs. and an air-to-air weapon with not-to-exceed dimensions of 7″ diameter x 144″ long with production quantity of >200 no later than 2027 for both weapons.”
Whether or not the air-to-air weapon design mentioned here is part of the larger work Castelion is doing on Blackbeard, or a separate project, is unknown. The company has previously said that it was aiming to have a more finalized Blackbeard design by 2027.
This is not the first time that work on an air-launched variation of Blackbeard has come up, either. In its 2026 Fiscal Year budget request, the Army said that the ground-launched version of the weapon that it expects to receive will leverage an “existing air-launched, extended-range Blackbeard design,” but did not elaborate. TWZ has reached out to the Army for more information in the past.
As noted, the Navy has had a stated requirement for an air-launched hypersonic anti-surface warfare capability for years now. Starting in 2021, the service had been pursuing an air-breathing hypersonic cruise missile to meet that need through a program called Hypersonic Air-Launched Offensive Anti-Surface Warfare (HALO). Raytheon and Lockheed Martin had been working on competing designs.
The Navy had hoped to begin fielding HALO before the end of the decade. However, in late 2024, the service scrapped plans to move the program to the next phase of development.
“The Navy cancelled the solicitation for the Hypersonic Air-Launched Offensive Anti-Surface Warfare (HALO) Engineering and Manufacturing Development (EMD) effort in fall 2024 due to budgetary constraints that prevent fielding new capability within the planned delivery schedule,” Navy Capt. Ron Flanders, a service spokesperson, told TWZ in April of this year. “The decision was made after the Navy conducted a careful analysis, looking at cost trends and program performance across the munitions industrial base compared to the Navy’s priorities and existing fiscal commitments.”
“We are working closely with our resource sponsors to revalidate the requirements, with an emphasis on affordability,” Flanders added at that time. “The Navy is committed to its investment in Long Range Fires to meet National Defense objectives, with priority emphasis on fielding continued capability improvements to the AGM-158C Long Range Anti-Ship Missile (LRASM).”
Castelion’s focus on lower-cost and producibility for Blackbeard, coupled with the schedule it is targeting for development of the missile, all align with the Navy’s stated post-HALO plans. The service had previously described HALO as a critical capability, especially in the context of future high-end fighting, such as one in the Pacific against China.
The Navy could well be looking at multiple options to meet this ongoing requirement for a new, air-launched, high-speed, anti-ship weapon. The service is already fielding an air-launched version of the Standard Missile-6 (SM-6), called the AIM-174B, ostensibly in the anti-air role. However, in its surface-launched form, the SM-6 also has an anti-ship capability, and the AIM-174B could be used in that role, as well.
As mentioned, the Navy could still pursue other versions of Blackbeard beyond an air-launched type. Previously stated plans for HALO also included the eventual development of variants that could be fired from ships and submarines.
Other services could be interested in air-launched variations of Blackbeard, as well. The U.S. Air Force has also awarded Castelion contracts in the past in relation to long-range strike weapon concepts, and TWZ has previously reached out to that service for more information.
All of this is also heavily contingent on Castelion meeting its schedule, cost, and other goals for Blackbeard. The Army’s budget documents show it is pursuing Blackbeard aggressively, but through a phased approach that offers multiple off-ramps.
Castelion has certainly received a new vote of confidence on Blackbeard, regardless of launch modes, with the new integration contracts from the Navy and the Army.
Contact the author: [email protected]