US Air Force begins flight testing of hypersonic cruise missile in Australia

The US Air Force has carried out the first flight test of its Hypersonic Attack Cruise Missile, confirming the milestone to the outlet The War Zone, which reported it first. According to the service, the Royal Australian Air Force released a HACM flight test unit over a designated test range in Australia.

The Air Force did not say which range was used, when the test took place, or which aircraft carried the missile. It also is not clear whether the weapon flew under its own power after release.

HACM uses a two-stage design. A rocket booster accelerates the missile to a high Mach speed, after which a scramjet-powered cruiser separates from the booster and dives toward its target. Scramjets do not work effectively at low speeds, so the missile must reach high velocity before its engine can take over.

Raytheon, now part of RTX, was chosen alongside Northrop Grumman in 2022 to develop the missile. The work draws on an earlier Defense Advanced Research Projects Agency effort, the Hypersonic Air-breathing Weapon Concept program.

The effort sits under the Southern Cross Integrated Flight Research Experiment, a US-Australian arrangement that the Air Force said rests on more than 15 years of cooperation between the two countries. The US Government Accountability Office had raised concerns in a 2024 assessment, according to the source.