The Royal Australian Air Force (RAAF) is working to integrate the United States Air Force’s Hypersonic Attack Cruise Missile (HACM) with its F/A-18F Super Hornets. This is in addition to their planned role in flight testing the missile.
In June 2024, the US Government Accountability Office (GAO), revealed that HACM all-up rounds will be tested in Australia by the RAAF.
What it didn’t say - and Defence has now confirmed - is that Australia is also integrating the weapon aboard the RAAF’s F/A-18F fleet more generally.
“Through the SCIFiRE agreement, the US and Australia continue to collaborate on HACM design and development, including efforts to integrate HACM on RAAF F/A-18Fs and using Australian test infrastructure for flight tests,” Defence told ADM in response to questions about the GAO report.
The decision to integrate HACM on Australia’s F/A-18Fs appears to be driven by the 2024 Integrated Investment Plan (IIP).
The IIP states that Australia’s fleet of F/A-18F and E/A-18G aircraft will fly until 2040, with the F/A-18F receive an unspecified hypersonic weapon as part of an ongoing upgrade program.
While Defence wouldn’t confirm if HACM has been formally selected for this requirement, given ongoing integration work and Australia’s broader collaboration on the program, it seems likely that HACM will fulfil the role.
Australia’s specific role in testing HACM is also not entirely clear.
According to the GAO, the US Air Force plans to buy 13 HACM rounds for testing, which is set to commence in October this year. It’s unclear when testing will transition to Australia.
“Australian weapons ranges offer operational flexibility for long range tests such as those planned under SCIFiRE. Some events in the test campaign in support of SCIFiRE will be conducted over Australian ranges, including Woomera,” Defence told ADM when asked about Australia’s role in testing the weapon.
Australia’s involvement in HACM is being driven through the SCIFiRE agreement.
SCIFiRE was established in 2020 as a partnership between Australia and the US to “develop and test” hypersonic cruise missile prototypes.
What wasn’t made clear at the time was that SCIFiRE would be directly contributing to the US HACM program.
“The preliminary design developed by Raytheon under SCIFiRE is being operationalised under the Hypersonic Attack Cruise Missile (HACM) program,” Defence told ADM.
Through the SCIFiRE program, Australia and the US commissioned three companies, Lockheed Martin, Boeing and Raytheon, to develop designs for HACM and progress them through to preliminary design review.
In September 2022, following a competitive evaluation of the designs, Raytheon was selected to build HACM for the US Air Force.
This is where it appears the SCIFiRE program transitioned into cooperative development program-like arrangement with the US Air Force to support HACM.
“Under the [SCIFiRE] partnership with Australia that was established in 2021, HACM engaged three weapons manufacturers, executed three preliminary design reviews, and competitively down selected to Raytheon in September 2022,” the Principal Director for Hypersonics in the Office of the Assistant Secretary of Defense for Critical Technologies, Dr James Weber, said in a written statement to the US Congress in March this year.
“This program recently conducted wind tunnel testing of the all-up round and static fire ground tests for its new rocket motor. In collaboration with Australia, the Air Force HACM program is on track to meet warfighter needs,” he added.
HACM isn’t the only new weapon being developed that may see use on Australia’s F/A-18Fs. During this year’s iteration of the Rim of the Pacific (RIMPAC) exercise, air launched SM-6 missiles - designated AIM-174Bs - have been observed on US Navy F/A-18E/F Super Hornets.