Known high-Mach programmes. It is unclear what programmes are being pursued, but it's worth noting that Lockheed Martin unveiled its spiritual successor, the SR-72 Son of Blackbird, years ago. The programme has since gone dark, although some analysts believe it remains ongoing by Lockheed and that it had an appearance in the 2022 movie, Top Gun: Maverick. The start-up company, Hermeus, is also working to build a high-supersonic Collaborative Combat Aircraft (CCA), Quarterhorse. It has the ambition to eventually develop hypersonic CCAs. There are also startups, like Australia's Hypersonix Launch Systems, which have secured investment from the British MoD and NASA to develop its reusable Spartan scramjet and various aircraft. One example is the eight-metre-long hydrogen-fuelled ISR aircraft called VISR. One thing these programmes have in common is that they are uncrewed, and it is entirely possible that a new generation of high-Mach, high-altitude aircraft will similarly be pilotless.

Demand for fighter engines is rising. The timing reflects growing demand for engines across the U.S. tactical-aircraft fleet. According to Breaking Defense, an August Air Force request for information projected peak demand for F100 engines could exceed 180 annually by fiscal year 2034, including requirements for F-15EX and F-16 aircraft operated by the United States and international customers. The Air Force said it was seeking greater manufacturing innovation and supply-chain resilience. A second production source could therefore give Pratt & Whitney additional capacity while reducing dependence on a single manufacturing pipeline. The F100 also has potential relevance to newer unmanned aircraft. Pratt & Whitney's own F100-PW-229 material describes the engine as suitable for current F-15 and F-16 aircraft as well as new fighter and unmanned platforms. For Hermeus, Quarterhorse provides the immediate application. The company is developing the unmanned aircraft for high-speed flight under a $219 million Defense Innovation Unit contract, with the eventual goal of reaching speeds up to Mach 3. Hermeus is also developing its own turbine-based combined-cycle propulsion technology, known as Chimera, for future high-speed aircraft. That system combines turbine and ramjet propulsion concepts and is separate from the licensed F100 production effort. The new agreement therefore gives Hermeus an unusual position for a relatively young aerospace company: it can manufacture a mature fighter engine while continuing to develop its own high-speed aircraft and propulsion technologies. For Pratt & Whitney, meanwhile, adding another American manufacturer could provide a way to expand F100 production as demand grows without creating an entirely new engine production line. The companies have not disclosed a production rate or specific start date for Hermeus-built F100 engines. But the agreement marks a significant expansion of the F100 industrial base and gives Hermeus a new role in sustaining one of America's longest-serving fighter engine families. Get the latest in engineering, tech, space & science - delivered daily to your inbox. You may unsubscribe at any time. Kaif Shaikh is a journalist and writer passionate about turning complex information into clear, impactful stories. His writing covers technology, sustainability, geopolitics, and occasionally fiction. A graduate in Journalism and Mass Communication, his work has appeared in the Times of India and beyond. After a near-fatal experience, Kaif began seeing both stories and silences differently. Outside work, he juggles far too many projects and passions, but always makes time to read, reflect, and hold onto the thread of wonder.

Hermeus unveils low-cost ramjet vehicle to democratise high-mach flight testing. The US-based Hermeus is developing a low-cost, expendable ramjet vehicle that could make sustained high-Mach flight testing faster, cheaper, and more accessible worldwide to researchers and industry alike in coming years ahead. September 15, 2026 LOS ANGELES. Hermeus is developing a new expendable, ramjet-powered vehicle designed to provide sustained high-Mach flight testing without the cost and complexity of building a bespoke aircraft for every experiment. Called Ramjet-X, the vehicle will be released from the company's reusable Quarterhorse aircraft after being carried to the speed and altitude required for ramjet operation. Once released, Ramjet-X will ignite its air-breathing engine and continue under ramjet power, while Quarterhorse returns to base for future missions. The architecture addresses one of the basic limitations of ramjet propulsion: a ramjet cannot produce useful thrust from a standstill. Unlike a turbojet, it has no compressor driven by a rotating turbine. Instead, it relies on the vehicle's forward speed to compress incoming air before fuel is injected and burned. That means a ramjet-powered vehicle first needs an external boost. Traditionally, this has involved a rocket booster, another aircraft or a large, expendable launch system. Hermeus says using a reusable Quarterhorse aircraft as the accelerator could make repeated tests more economical and operationally practical. The company has not disclosed every performance parameter for Ramjet-X, including its precise top speed, range or payload capacity. However, its stated purpose is to operate in sustained high-Mach conditions, creating a platform for testing propulsion systems, sensors, communications equipment, materials, autonomy software and other aerospace technologies. "High-speed flight testing is extremely expensive, and you don't get many shots at it," Hermeus chief executive Zach Shore said. The company believes Ramjet-X can reduce that barrier by offering a repeatable test vehicle rather than requiring customers to develop an entire high-speed aircraft programme for each experiment. Hermeus plans to offer the capability as high-Mach Flight Test as a Service. Customers would be able to install experimental payloads and gather data in an environment that is difficult to recreate in wind tunnels or computer simulations. The model could appeal to defence contractors, research institutions, space companies and manufacturers developing components for fast aircraft and missiles. Ramjet-X is also connected to Hermeus's broader work on combined-cycle propulsion. Its Chimera engine concept combines turbine and ramjet technologies, allowing different propulsion modes to operate at different stages of flight. A turbine can provide thrust at lower speeds, while the ramjet takes over after the vehicle reaches conditions suitable for high-speed air-breathing propulsion. The distinction is important because a purely ramjet-powered aircraft cannot simply take off from a runway and accelerate through the lower-speed regime. Ramjets generally become useful only after achieving substantial forward velocity and perform most efficiently at supersonic speeds. They can operate at much higher speeds, but aerodynamic heating, material durability, fuel control and stability become progressively more difficult. Hermeus is conducting Ramjet-X engine testing at its HEAT facility in Jacksonville, Florida, while engineers develop high-temperature structures at the company's headquarters in El Segundo, California. Integrated vehicle testing is currently planned for 2027. The programme's most significant promise may be its economics. High-speed flight research has traditionally depended on expensive, limited-use aircraft, large test ranges and lengthy preparation cycles. An expendable vehicle could eliminate refurbishment after each mission, while the reusable carrier could lower the cost of getting the test article airborne. There are substantial risks. The company must prove that Ramjet-X can survive severe aerodynamic heating, maintain stable propulsion and transmit useful data during a demanding flight. It must also demonstrate that its reusable launch architecture can operate reliably and safely. If successful, however, Ramjet-X could turn high-Mach testing from an occasional national programme into a more accessible commercial service - giving aerospace developers more opportunities to test, fail, improve and fly again.