Australian startup's 3D-printed scramjet reaches Mach 7 in Pentagon-backed hypersonic test

On a February night in 2026, a rocket lifted off from Wallops Island in Virginia carrying something that had never flown before: a hypersonic aircraft with an engine built layer by layer in a 3D printer. The DART AE, designed by Australian startup Hypersonix Launch Systems, rode Rocket Lab's HASTE booster into the upper atmosphere before igniting its hydrogen-fueled scramjet and accelerating to Mach 7—more than three times the speed of the Concorde, and fast enough to cross the continental United States in under an hour.

The flight on February 27th was called Cassowary Vex, and it represented something the U.S. military had been chasing for years: a way to test hypersonic technology quickly and cheaply. The Pentagon's Defense Innovation Unit had selected Hypersonix in 2023 and committed $46 million to the effort through a program called HyCAT, designed specifically to accelerate the pace of American hypersonic testing. The problem the program was trying to solve was not physics—the U.S. understood how scramjets worked—but manufacturing. Traditional hypersonic engines required precision machining of exotic metal alloys, a process that took months, demanded specialized tooling, and made each prototype expensive enough to limit how often engineers could actually fly and learn. China, by contrast, had been testing hypersonic vehicles at a much higher frequency, not necessarily because it had better scientists but because it had built a faster, cheaper industrial pipeline.

The DART AE itself was modest in size: 3.5 meters long, weighing 300 kilograms, with a range of 1,000 kilometers. But its engine, called SPARTAN, was the real innovation. It was a scramjet—a supersonic combustion ramjet—meaning it burned fuel while keeping the air moving faster than sound inside the combustion chamber. At speeds above Mach 5, slowing the air down to subsonic speeds for combustion generates so much heat it destroys the engine. A scramjet avoids this by maintaining supersonic flow, but the tradeoff is that mixing and igniting fuel at those speeds becomes extraordinarily difficult. The SPARTAN solved part of this problem through materials: it used nickel-chromium Inconel alloy for the main structure and ceramic matrix composites for the leading edges, where temperatures are most extreme. But the real breakthrough was manufacturing. By 3D-printing the engine instead of machining it, Hypersonix compressed the design-to-flight cycle from months to weeks. That speed matters because it means engineers can test, learn, modify, and test again in rapid succession—the kind of high-cadence iteration that had given China an advantage.

The hydrogen fuel was not chosen for environmental reasons alone. Hydrogen has three times the energy density of kerosene by weight, meaning the same mass of fuel delivers far more energy. In a hypersonic vehicle where every kilogram affects acceleration and thermal management, that difference is decisive for extending range and performance. Hydrogen also provides superior regenerative cooling: it can circulate through the engine walls, absorb heat before combustion, and help the motor survive in extreme conditions. The February flight was designed partly to validate this concept under real conditions.

What made the SPARTAN different from other scramjets was its ability to ignite and shut down multiple times during a single flight. Most scramjets operate in a more limited way, following a fixed ballistic trajectory after ignition. The SPARTAN's throttle capability allowed the DART AE to execute planned maneuvers—changes in direction and altitude—rather than simply coasting on a predetermined path. This flexibility moves the technology closer to something that could actually be controlled in a real mission, not just a brief demonstration of speed.

The HyCAT program itself reflected a strategic shift in how the Pentagon thought about hypersonic development. Rather than trying to build a single perfect weapon, the Defense Innovation Unit wanted to create industrial infrastructure capable of flying more tests, learning faster, and shortening the interval between flights. Hypersonix was the first company selected, and the February launch was the second HASTE mission under the program's logic, reinforcing the goal of establishing a more frequent platform for hypersonic experiments.

Hypersonix is already planning the next step: autonomous hypersonic aircraft capable of sustained flight at Mach 12, using the same SPARTAN engine but with a redesigned airframe to handle even greater thermal loads. Kratos Defence & Security Solutions has been designated to acquire and operate DART AEs for multiple U.S. Department of Defense customers, using its Zeus motor family as a booster. The arrangement combines startup innovation with an already-established military supply chain. What began as a manufacturing problem—how to build and test faster—has become a pathway toward a new class of hypersonic vehicles that could reshape how the military thinks about speed, range, and control at the edge of space.