AirLaunched

Hermeus is developing an expendable ramjet-powered aircraft, Ramjet-X, which will be air-launched from its reusable, F-16-sized Quarterhorse high-speed drone. The result aims to create a two-vehicle architecture intended to make high-speed flight testing less dependent on expensive, single-use test platforms. That would give Hermeus and potential customers a way to conduct repeated high-Mach flight tests without expending a large booster on every mission.

The company unveiled the concept today. Hermeus says the Ramjet-X will be carried beneath Quarterhorse and released at a speed of around Mach 3, at which its ramjet can begin operating. The smaller vehicle will then accelerate, climbing to around 100,000 feet, and a speed in the region of Mach 4. Quarterhorse will then return to base and be available for another mission.

Imagery released by Hermeus shows a Quarterhorse carrying a Ramjet-X mounted on a pylon under each wing, indicating that two different high-speed tests can be carried out in a single sortie. Intriguingly, the Quarterhorse is shown with no fewer than six underwing hardpoints in all, suggesting that other kinds of external payloads are envisaged.

Hermeus has not released detailed performance specifications for Ramjet-X, including its range, payload capacity, or the critical expected cost per flight. We have reached out to the company for more information.

Images released by the company show a relatively compact, missile-like vehicle with delta wings incorporating prominent dihedral. There are no horizontal tail surfaces, but a conventional vertical fin is complemented by a ventral fin. Axios reports that Ramjet-X is approximately 22 feet long and 7 feet wide.

In terms of appearance, and also thanks to its ramjet propulsion system, the vehicle is outwardly very reminiscent of the Lockheed’s D-21 Tagboard supersonic spy drone. However, at more than 40 feet long and with a wingspan of 20 feet, the D-21 was significantly bigger. Overall, the entire concept recalls the Cold War-era D-21 and its M-21 mothership, on a smaller scale.

The basic concept aims to address a longstanding problem with ramjet flight testing. Unlike a conventional jet engine, a ramjet cannot provide useful thrust from a standstill. The vehicle therefore has to be accelerated to a sufficiently high speed before the ramjet can take over.

That acceleration can traditionally require another propulsion system, including an expendable rocket booster. Hermeus is proposing to substitute a reusable aircraft for that initial boost. It is unclear if the Ramjet-X vehicles are similarly recoverable, but we have asked Hermeus for more details here, too.

As it stands, flight-test programs of this kind are often constrained not only by the cost and availability of test infrastructure, but also by the limited availability of suitable airspace and range access. A reusable carrier aircraft could help address both challenges, allowing multiple Ramjet-X vehicles to be deployed from airports near a designated test range as required and launched only once the vehicle is within the approved test area. That flexibility could reduce the need for a new large booster for every experiment while also making it easier to conduct tests, including at shorter notice, within increasingly constrained airspace.

Hermeus says Ramjet-X is being designed not just for its own development work but as a potential test platform for outside customers. The company is calling the concept “Flight Test as a Service,” with customers able to fly payloads including sensors, communications equipment, computing and autonomy systems, materials, and propulsion hardware.

The program reflects a broader push toward increasing the availability of commercial high-speed flight testing that has attracted U.S. government interest.

Hermeus was also selected by the Defense Innovation Unit for work under its Hypersonic and High-Cadence Airborne Testing, or HyCAT, effort. That program is intended to use commercial flight-test capabilities to expand the government’s access to relevant high-speed environments.

The company is also pursuing its own increasingly ambitious Quarterhorse aircraft. Its Quarterhorse Mk 2.1 completed an uncrewed supersonic flight earlier this year, reaching Mach 1.21 on its third test flight. The company’s roadmap calls for subsequent Quarterhorse variants to progressively increase speed and address the thermal and propulsion challenges associated with high-Mach flight.

The imagery released for Ramjet-X shows a different Quarterhorse configuration than the 2.1 version, including beefed-up landing gear with twin nosewheels. The requirement for release of the Ramjet-X at Mach 3 suggests that its launch platform will be the Quarterhorse Mk 2.3, which will be the first to reach this kind of speed. This summer, Hermeus confirmed that its second supersonic aircraft, the Quarterhorse Mk 2.2, and the Mach 3-capable Mk 2.3 aircraft were under construction.

For its future Quarterhorse Mk 3, Hermeus has been developing Chimera, a turbine-based combined-cycle propulsion system. This is intended to transition from turbine operation to ramjet operation as speed increases.

Ramjet-X effectively separates part of that problem into another aircraft and the system could also be useful for experiments that do not require an entire hypersonic aircraft.

For example, an organization developing a high-temperature material might need to know how it behaves in an actual high-speed flight environment, rather than only in a ground test. The same could apply to weapons, sensors, communications systems, guidance hardware, onboard computers, or other components intended for high-speed vehicles.

So far, however, it’s not clear what kind of flight profiles Ramjet-X will provide. Hermeus has mentioned a cruise phase lasting “tens of minutes.”

But a short-duration dash through a high-Mach regime is not equivalent to sustained flight at those speeds. The duration available to an experiment, thermal loads, acceleration, vibration, available electrical power, telemetry, maneuverability, and payload mass will all determine what can actually be tested.

The company says it is already testing the Ramjet-X propulsion system at its High Enthalpy Air-Breathing Test facility in Jacksonville, Florida. High-temperature structures are also under development at its El Segundo, California, headquarters. Integrated vehicle testing is currently planned for 2027.

The HEAT facility itself is part of Hermeus’ effort to establish high-speed propulsion test infrastructure. The company says the facility is being developed to eventually provide continuous high-Mach airflow for more flight-like ground testing.

Ramjet-X has yet to fly, but if it performs as intended, it could help lower one of the major barriers to obtaining real-world flight data at high Mach numbers. At the same time, the company is entering a market that is attracting growing interest from other aerospace firms, which are also expanding their high-speed flight-test capabilities, especially to capitalize on the broader hypersonics boom, including Stratolaunch.

There is fairly clear potential weaponization of this concept, for strike and surveillance missions, as well, although there has been no indication of that being in the works at this time.

The planned 2027 integrated testing should provide the first meaningful indication of whether the concept can progress to become a practical high-speed test capability.

Contact the author: thomas@thewarzone.com

Russia is displaying some of its newest air-launched precision weapons in public for the first time at the El Alamein International Airshow in Egypt this week. The S-71K Kovyor and related S-71M Monokhrom, and the S8000 Banderol, reflect Russia’s effort to field larger numbers of relatively inexpensive standoff weapons alongside its more sophisticated and costly missile types. As such, their development and early employment are closely tied to the war in Ukraine, but they also reflect wider global interest in these kinds of weapons.

The weapons, seen in the tweet embedded below, comprise, clockwise from top left: S-71K Kovyor, an unknown smaller guided munition, S8000 Banderol, and S-71M Monokhrom:

For Russia, the requirement has become increasingly important as the war in Ukraine has evolved into a prolonged contest in which industrial capacity is as critical as technology. Russia has expended huge numbers of cruise and ballistic missiles against Ukrainian targets while also developing an enormous strike-drone campaign. At the same time, Ukrainian air defenses have become progressively more capable, forcing Moscow to use combinations of missiles, drones, decoys, and different flight profiles to penetrate or saturate the defensive network. One lesson is the fact that a weapon does not necessarily have to be as capable as a high-end cruise missile if it can be manufactured in much greater numbers and still present a credible threat to the target.

The S-71M, which TWZ previously reported on in detail after Ukrainian intelligence obtained an example, is a compact, turbojet-powered weapon with a distinctly angular airframe intended to reduce its radar signature. Imagery from Egypt gives a better look at its front end, including a faceted nose flowing into a broad central fuselage. The nose has at least one optically flat transparency for an infrared or TV seeker. Its wings are sharply swept and fold against the belly of the weapon for carriage, while the rear of the weapon terminates in an inverted-V tail arrangement. The overall shape is notably different from Russia’s more conventional cruise missiles of the past.

Ukrainian analysis found that the S-71M incorporates an OFAB-250-270 high-explosive fragmentation bomb as its warhead and relies primarily on inertial guidance, rather than carrying a sophisticated terminal seeker, although the seeker window raises questions about that.

Ukrainian intelligence also described its construction as being relatively straightforward, with fiberglass composite material making up much of the outer structure and no evidence identified of specialized radar-absorbing coatings.

As we noted previously, the weapon appears intended as a less expensive, but still survivable standoff weapon option that can be produced in significant numbers.

The S-71M has been tested from the Su-57 Felon fighter, also present at El Alamein. In a press release, the United Aircraft Corporation (UAC), responsible for the Su-57, said that the S-71M and the S-71K displayed alongside it “were designed for fifth-generation fighters,” although there is no reason why they couldn’t be launched from a wide variety of platforms.

A Su-57 performing at El Alamein, with one of its main internal weapons bays apparently loaded with Kh-69 standoff missiles:

Regardless of launch platform, the nature of the war in Ukraine make that the S-71M particularly useful. Russia has increasingly relied on extemporized glide bombs for attacks against targets relatively close to the front, but those weapons require the launching aircraft to operate within a certain distance of Ukrainian defenses. At least in their earlier iterations, such weapons were also crude and prone to failure. Longer-range cruise missiles offer considerably greater standoff but are more complex and expensive. The S-71M sits somewhere between those categories, providing an air-launched, powered weapon with a relatively large warhead and some degree of low observability without the cost and complexity of a full-size, truly stealthy cruise missile.

The S-71K appears to represent a more capable version of the basic concept. Public information remains limited, but the weapon has been associated with electro-optical guidance and greater onboard processing, potentially giving it a capability to deal with targets in a more flexible manner than the largely pre-programmed S-71M. Exactly how that capability is employed, and how autonomous the weapon actually is, remain less clear from the imagery and information released to date.

As displayed at El Alamein, the S-71K retains the overall faceted, low-observable appearance of the S-71M but has a visibly different airframe and wing arrangement. Its body is notably broad and compact relative to its length, with folding wings that are relatively thick, and a more refined inverted-V tail giving it more the appearance of a small uncrewed aircraft than a conventional air-to-surface missile.

Meanwhile, the Banderol represents a somewhat different path to the same general problem. Ukraine’s intelligence service previously obtained and analyzed an example of the small jet-powered cruise missile, which TWZ reported on last year. The weapon is considerably smaller than Russia’s principal cruise missiles and has been associated with launch from drones and helicopters. Its reported range of around 500 kilometers (311 miles) and relatively small warhead make it something of a complementary system intended to provide another, more economical way of putting a precision weapon onto a target from the air.

In terms of its appearance, the Banderol is more conventionally missile-like, with an ogival central fuselage, a pointed nose, and sharply swept folding wings. Its proportions underline just how small it is compared with Russia’s better-known air-launched cruise missiles.

The Banderol is particularly relevant in the context of the economics of the Ukraine conflict. Russian forces have increasingly used combinations of relatively inexpensive one-way attack drones and more expensive cruise and ballistic missiles. The drones can be produced in large numbers and used to complicate air-defense operations, while the more capable missiles provide greater speed, range, payload, or penetration capability. A small turbojet-powered weapon such as Banderol offers another point on that spectrum.

At leats one image has recently emerged showing a Banderol carried by a Russian Mi-28NM Havoc attack helicopter. This would be in line with unconfirmed reports from Ukraine last month that Russia was using the Mi-28 as an additional launch platform for the weapon, including firing them from over the Sea of Azov to attack targets around Odesa.

Its reported use also illustrates how the distinction between a cruise missile and a large one-way attack drone is becoming increasingly blurred. The Banderol incorporates a conventional missile-like airframe and jet propulsion but has been associated with drone operations and makes extensive use of commercially available components. TWZ’s earlier examination of the weapon also highlighted the extent to which modern Russian weapons programs can combine relatively simple airframes with foreign-sourced electronics and propulsion technology.

Likely Banderol loitering munition on the ground (perspective exaggerates it’s size) and under Orion drone.

Banderol has been reported as one of the munition used in recent strikes and appears to use a jet engine and a FAB-100 warhead or similar. pic.twitter.com/j50DUsNuVe

— krakek (@krakek1) April 27, 2025

Seen together at El Alamein, the three weapons provide an unusually useful snapshot of where Russian air-launched strike development is heading. They are presented alongside a fourth, so-far unidentified munition. This unnamed weapon is notably short and fat, with a cruciform tail, and an optical window in the nose. Its overall size and shape suggest it may have been developed specifically to arm drones.

The appearance of the weapons at an arms fair underscores the fact that Russia is not the only country confronting the problem of producing and fielding sufficient precision weapons at an acceptable cost. The growing interest in lower-cost cruise missiles, loitering munitions, attritable aircraft, and other forms of expendable precision strike is now evident well beyond Russia.

Russia is also clearly trying to make these weapons harder to intercept, an increasingly important consideration as Ukrainian air defenses have demonstrated an ability to shoot down even glide bombs in some circumstances. The S-71K in particular incorporates unusually pronounced low-observable shaping, suggesting that survivability was also a central requirement from the outset.

There is, however, a significant complication to Russia’s attempt to turn its wartime experience into an export opportunity. Buying any kind of weapons from Moscow has become considerably more difficult because of sanctions, restrictions on access to foreign technology and financing, and the wider political risks associated with maintaining a Russian defense relationship. Those factors matter just as much to a prospective customer as the performance of the weapon itself.

Author’s note: earlier reporting on the S-71 family appears to have transposed the S-71K and S-71M versions. Most authoritative accounts now indicate that the more refined, more stealthy version is the S-71K Kovyor (meaning carpet), while the simpler weapon is the S-71M Monokhrom.

Contact the author: thomas@thewarzone.com