USAFs

The U.S. Air Force’s scramjet-powered Hypersonic Attack Cruise Missile (HACM) has finally reached the flight test phase, with at least one “release” having been carried out so far over a range in Australia. HACM has suffered significant delays, and the Air Force has taken the risky step of scaling back overall testing plans to try to keep the program on schedule. The stated goal is to be able to make a decision to start rapidly acquiring HACMs in 2027.

The Air Force has been working on HACM in cooperation with the Royal Australian Air Force (RAAF). The program has been conducted, in part, under the broader umbrella of the U.S.-Australian Southern Cross Integrated Flight Research Experiment (SCIFiRE). The Defense Advanced Research Projects Agency’s (DARPA) Hypersonic Air-breathing Weapon Concept (HAWC) project also fed into HACM. Raytheon (now formally RTX), in cooperation with Northrop Grumman, was chosen to develop the missile in 2022. The weapon has reportedly been designated AHM-4A in a new branch of the U.S. military’s joint service nomenclature system for aircraft and missiles.

“The U.S. Air Force, in partnership with Australia, has conducted a flight test of the Hypersonic Attack Cruise Missile (HACM) as part of our continuous work to advance long-range strike capabilities,” an Air Force spokesperson confirmed to TWZ today. “This effort is part of the Southern Cross Integrated Flight Research Experiment (SCIFiRE), a collaborative agreement built on more than 15 years of partnership between our two nations.”

“Leveraging this enduring alliance, the Royal Australian Air Force executed the release of a HACM flight test unit over a designated Australian test range, gathering crucial data to advance the program’s objectives,” the spokesperson added. “The flight was the culmination of an extensive series of tests designed to measure the missile’s performance under realistic flight conditions.”

The spokesperson did not name the test range where the “release” was conducted or say when that occurred. Whether the missile flew under its own power for any amount of time after release is unknown. What aircraft was used to carry the missile aloft is also not known. TWZ has reached out for more information.

The Air Force did say previously that it planned to conduct HACM launches in Australia. The expectation has long been that this would be done at the country’s sprawling Woomera Test Range, which provides an ideal location for extended-range flight testing activities in general. The U.S. and Australia have partnered on other hypersonic testing at Woomera in the past, as seen in the video below. The remote inland location of the range complex makes it well suited for conducting more sensitive tests away from prying eyes, as well.

HiFiRE 5B rocket reached Mach 7.5

The Government Accountability Office (GAO), a Congressional watchdog, has also reported in the past that RAAF F/A-18F Super Hornets would be used to conduct at least some of the HACM test launches. This would fit with today’s statement from the U.S. Air Force saying that it was the RAAF that “executed the release.” The Air Force’s initial launch platform is the F-15E Strike Eagle, though others are expected to follow.

To date, neither the Air Force nor Raytheon has released a confirmed picture or rendering of HACM. In 2023, the Air Force did release a picture, seen below, showing an air-breathing hypersonic cruise missile test article related to either HACM or the preceding HAWC effort.

“The missile consists of two stages, a rocket booster and a scramjet cruiser, which separates from the booster and eventually dives toward its target,” according to GAO. Scramjets do not function effectively at lower speeds, and designs powered by them require some form of initial boost to a high Mach velocity. Hypersonic speed is generally defined as anything above Mach 5, but what HACM’s peak speed might be is unknown.

Two-stage air-breathing missile-like hypersonic vehicle designs have been tested on several occasions in the past. This includes Boeing’s scramjet-powered X-51 Waverider and HyFly 2 hypersonic test vehicles, among others. The X-51 (as its name indicates) and HyFly 2 also notably had so-called ‘waverider’ configurations designed to ‘skip’ on the shockwaves generated during high-speed flight to help provide additional lift. Whether HACM might also use this principle is not known.

X-51A WaveRider Scramjet Second Hypersonic Flight Test

It’s also worth noting here that Castelion’s Blackbeard hypersonic missile also has a two-stage configuration. It remains unconfirmed whether or not the second stage of that weapon is powered, but it does not appear to be an air-breathing design either way. Castelion is currently developing an air-launched version of Blackbeard for the U.S. Navy, which is also in flight testing now, as well as a ground-launched type for the U.S. Army. You can read more about that missile here.

Scramjet-powered air vehicle designs, including aircraft and missiles, have historically proven challenging. As noted, HACM has suffered delays over the years. The original goal had been to begin flight testing in 2024, which slipped first to 2025 and then 2026.

“The HACM program is on track to conduct its first flight test in the second quarter of fiscal year 2026, but officials said there is effectively zero margin left in the schedule for the rapid prototyping effort. The program has already descoped the rapid prototyping effort from seven to five planned flight tests,” GAO said bluntly in a report published in July. “The Air Force plans to produce 13 missiles during the rapid prototyping effort, including test assets, test spares, and operational rounds.”

“If a significant flight test failure occurs, it is likely that the program will not be able to complete all five tests within the 5-year rapid prototyping timeframe,” the report continued. “According to the program, completing at least the first three flight tests is critical for informing the Air Force’s decision to initiate a rapid fielding effort and procure HACM in fiscal year 2027.”

GAO’s July report, which had a January cutoff date, noted later on that the Air Force’s target date for initiating the rapid fielding effort, more specifically, was the first quarter of Fiscal Year 2027. This fiscal period began last Thursday and runs through the end of the year. Whether the service is still aiming to keep to that part of the schedule is unclear, but it would seem extremely difficult to do so.

“The HACM program has taken on risk to maintain its current schedule. According to program officials, maintaining the schedule has required aggressively resequencing activities to focus almost exclusively on those necessary to support the first flight test date,” GAO’s report added. “In some cases, officials said this has involved risky strategies, such as concurrently performing parts validation testing while completing the system’s design, which could require the redesign of key parts if they fail validation testing.”

In terms of U.S. hypersonic missile developments, challenges have also not been limited to scramjet-powered types like HACM. Air Force, Navy, and Army efforts to develop a variety of air- and surface-launched hypersonic missiles in various sizes and configurations have all suffered setbacks in the past decade or so. The Navy notably cancelled its own air-launched hypersonic cruise missile program, called Hypersonic Air-Launched Offensive Anti-Surface Warfare, or HALO, last year. The service subsequently shifted focus to the aforementioned Blackbeard under a program called the Multi-mission Affordable Capacity Effector (MACE). This has all prompted particular concerns about a growing and increasingly worrisome gap in this regard between the United States and its chief global competitors, especially China.

There is also a cost question. HACM traces to a time when hypersonic missiles were generally viewed, at least publicly, as highly capable, but also higher-cost and lower-density, assets. Blackbeard, for example, reflects a more recent push to develop and field more economical munition designs across the board that can also be more readily produced at scale. This demand signal has become even more pronounced in light of the dwindling American stockpiles of critical munitions due to the conflict with Iran, as well as other crises globally in recent years. More exquisite munitions, including hypersonic types, will still be part of the larger U.S. arsenal going forward.

Regardless, the U.S. military, as well as its Australian counterparts, have made it clear in the past that they view hypersonic weapons as critical for success in future conflicts, especially high-end fights, such as one in the Pacific against China. In general, air-breathing hypersonic cruise missiles offer a valuable and highly flexible way to strike targets, especially time-sensitive ones, quickly and over extended ranges. The weapon’s high speed and maneuverability drastically increase its ability to penetrate through enemy air defenses and reduce the total time an opponent has to react.

Whether or not the Air Force will be able to avoid any more major delays with HACM remains to be seen. The service’s goal to start at least limited production of HACM before the end of 2027, if not sooner, is even more ambitious now after years of schedule slips. As mentioned, officials have already acknowledged there was no more margin for error at the start of the year. There are many questions still about what form any initial fielding will take, and how that might be further impacted by the truncated testing plan.

The HACM program has at least now hit the important milestone of beginning flight testing.

Contact the author: joe@twz.com

U.S. Air Force Collaborative Combat Aircraft (CCA) are set to take part in a large-force employment (LFE) exercise for the first time later this year. Sending CCAs to the next iteration of the Emerald Flag test exercise is another important new stepping stone toward fielding the drones operationally.

“We have not yet done a LFE with these [CCAs], for real. The first one is going to be Emerald Flag. That’s in December,” Lt. Col. Lyndon “OTTO” Bartlett, Director of Operations for the Experimental Operations Unit (EOU) at Nellis Air Force Base in Nevada, said earlier today. “That’ll be our first tip dip of the toe in an actual force integration.”

Bartlett was speaking during a panel at the Air & Space Forces Association’s (AFA) 2026 Air, Space & Cyber Conference, at which TWZ is in attendance. The EOU has been leading Air Force efforts to lay the groundwork for future CCA operations. The unit has already been conducting various types of testing using prototypes of the General Atomics FQ-42A Vengeance and Anduril FQ-44 Fury. The Air Force announced in June that its initial operational CCA fleet would consist of a mix of FQ-42s and FQ-44s.

The Air Force’s 96th Test Wing at Eglin Air Force Base in Florida first began hosting Emerald Flag exercises in 2020. The exercise series has historically focused heavily on demonstrating new and improved aerial networking architectures and other command and control capabilities, which will be especially critical elements for future CCA operations. Emerald Flag, with its not purely limited to the air domain, is often tied in with other large force test exercise series. Other branches of the U.S. military regularly take part, as well.

It is worth noting here that Boeing’s MQ-28 Ghost Bat, a CCA-type design, did take part in Valiant Shield 26, another LFE exercise, earlier this year. The EOU was also involved. However, the MQ-28, originally developed for the Royal Australian Air Force, is not officially part of the Air Force’s CCA program at present.

Emerald Flag in December “will, in OTTO’s mind, be the first time that we will ever do some CCA end-to-end chain [demonstration] live. That’s the first time we’ll ever be integrated in a fourth- and fifth-gen combined OCA [offensive counter air] push,” Lt. Col. Bartlett added. “It’ll be small, but those type [sic] of building blocks are where I think you get the intangibles like trust in the CCA.”

“Those learnings are going to be just as valuable as the technical, [like] does the radio work properly? Does the button I push to say ‘target’ work properly?” he continued.

U.S. military officers, including tactical jet pilots, regularly talk about the critical need for trust in autonomous systems to perform as expected when directed in future operations. Establishing that trust, and doing so in real-world environments, is seen as foundational to answering larger outstanding questions about how CCA-type drones will be deployed, launched, recovered, supported, and otherwise operated, let alone employed tactically.

The EOU, together with other partners within the U.S. military and industry, have been working for years now to validate and improve autonomous capabilities in the virtual realm, and then test in more limited real-world contexts. Virtualized testing does offer immense benefits for rapid iterative development of the underlying software ahead of live demonstrations.

“If it’s in a simulated environment, it’s immediate,” Lt. Col. Bartlett said during the panel when asked about the “feedback loop” in testing the EOU is already taking part in. In that environment, “when the mission autonomy iterations are happening, our guys are literally with the programmers … They give the feedback, and if it’s possible to do immediately, they take that feedback. If not, then they work on it on the next turn of the software.”

Real-world testing, of course, offers opportunities to explore additional aspects of future CCA operations, including when it comes to loading weapons and maintenance. A key component of the Air Force’s vision for CCA employment is being able to forward deploy the drones to far-flung locations, including airstrips with limited infrastructure and access to logistics chains. Rapid, distributed deployments like this are central to still-evolving concepts of operations currently referred to collectively as Agile Combat Employment (ACE). The EOU has been involved in at least two rounds of ACE-focused testing this year, one at Edwards Air Force Base in California in April and another at Creech Air Force Base in Nevada in July. TWZ was the first to report on the latter event.

Visualizing ACE

During the panel today, Lt. Col. Bartlett also talked more generally about work EOU has done to date. This has included exploring “sortie generation, how easy they are to maintain, [and] how small a footprint could be.”

“We’ve been pleasantly surprised. The jets are extremely easy to maintain,” he continued. “We’re at a one-to-one maintainer-to-airplane ratio, which is crazy small.”

With “CCAs, [it] seems like because they’re a little bit simpler, because their role is so focused, what we found is that just about any – not just about, but we found that any AFSC [Air Force Specialty Code; alphanumeric codes used to identify specific jobs within this service] can be trained to generate sorties to load weapons, and we’ve done some of those things already,” he further explained. “It’s our job to bring them [CCAs] out and make sure that, beyond the technical specifications of it, that we’re kind of experimenting with the more complex things like logistics, and C2 [command and control], and how do we battle manage these things.”

The head of the EOU did acknowledge challenges that still have to be surmounted. This notably includes hurdles currently imposed by Federal Aviation Administration (FAA) regulations on the operation of fully uncrewed aircraft, even by the U.S. military, within U.S. airspace. This is further compounded by the explicit intention to operate CCAs with far more minimal human engagement compared to most existing drones.

“Mission autonomy is going to be the secret sauce that lets these things become decisive or not, and we’ll know that over the next couple years as that develops,” according to Bartlett. “If I were to identify the two biggest problems from the trenches of the EOU, [one] is FAA integration or policy implications to an autonomous airplane.”

“So these things don’t have pilots. They’re not RPAs [remotely-piloted aircraft]. They’re not manned fighters. They have no pilots,” he continued. “Our system is not set up for that, and that is a challenge that we are finding extremely hard to navigate through, and to not go around, but to make a policy.”

“We need to make sure the Air Force is ready for these things, to set policies that make sure the enterprise and the country is [sic] ready to receive these, and internalize an autonomous fighter that does not have a pilot that is running on a mission autonomy agent that doesn’t listen to ATC [air traffic control],” he added.

The second problem, per Bartlett, is making sure the Air Force develops new internal policies and doctrine that are not “copy and pastes from old regulations” that do not take into account the specific nuances that CCAs will bring. What the service needs is “something that enables us to move quickly with these things, to weigh what we need, and to experiment with novel types of air superiority.”

All of this circles back to the discussion of trust in autonomous capabilities. It also speaks to the potential for future operations where CCAs could operate far more independently.

“It’s in the name that they’re collaborative,” Bartlett said. “Taking them out of that could technically be effective, but would not enhance the joint force the way that we see a collaborative, integrated force package to be.”

“What we need autonomously to do is written down. I won’t discuss the particulars in this forum, but we know what we need it to do, or we know what we think it really needs to do,” he noted. “We’ve structured our experimentation game plan to analyze ‘can it do those things?,’ and if not, then how do they need to be different? And then as they iterate on it, which we’ve already seen a couple times, we get that at the EOU, we get the new version down, we fly it again. Is it fixed? Yes or no.”

Some members of industry are clearly envisioning futures with different definitions of ‘collaborative’ that could lean more toward independent operations involving highly autonomous drones.

What “the whole entire program is trying to do is [figure out] what is the requirement to put out into the field to get to the warfighter and to start operating this thing this [sic; in] real time?” Robert “Otis” Winkler, Vice President of Corporate Development & National Security Programs at dronemaker Kratos, another one of the panelists, said. “The collaborative part of this makes it a much easier, I think, technical problem to be able to limit and grow the autonomy as you field this.”

“I think eventually we may see these aircraft utilized as collaborative aircraft, but not in conjunction with your traditional pulsed operation, but in support of that pulsed operation when the pulse isn’t there yet. But I do think that that is a bit of a stretch goal that’s going to be down the road.”

CCAs “have been designed really around increasing both survivability and lethality of current force packages. So there are many manned platforms that you would describe in the exact same fashion,” Jason Levin, Senior Vice President for Air Dominance and Strike at Anduril, who was also on the panel, said. He was responding here to a specific question about whether his use of the term “fighter” to describe these drones implied more emphasis on independent operations.

All of this underscores the importance of bringing CCAs to Emerald Flag in December, as well as other events in the future offering opportunities to see how the drones really fit in with other crewed platforms. The Air Force is hoping to start seeing CCAs enter operational service around the end of the decade, and have 500 of them, at least, in inventory by 2032.

During the panel today, the EOU’s Lt. Col. Bartlett made clear that “we’re going to learn a lot over the next couple years.”

Contact the author: joe@twz.com