Europe's Hypersonic Leap: INVICTUS Spaceplane to Fly by 2031, Building on SABRE's Legacy

A groundbreaking new chapter in aerospace innovation has begun, as the European Space Agency (ESA) and the UK Space Agency (UKSA) throw their weight behind INVICTUS, a pioneering research programme set to develop a Mach 5-capable reusable aircraft. This ambitious project, led by UK-based Frazer-Nash Consultancy, aims for its first flight by early 2031 and represents a significant step towards enabling routine, horizontal space launches.

At the Heart of the Innovation: The SABRE Engine's Pre-Cooler Technology

The INVICTUS programme is not starting from scratch; it is strategically built upon decades of development in the Synergetic Air-Breathing Rocket Engine (SABRE). SABRE, originally developed by UK aerospace firm Reaction Engines Ltd (REL), is a revolutionary hybrid air-breathing rocket engine designed for dual-mode operation.

• Air-Breathing Mode: During the initial ascent, SABRE is designed to scoop up atmospheric air and accelerate to speeds of up to five times the speed of sound (Mach 5).
• Rocket Mode: At approximately 25 km altitude, it would then seamlessly switch to pure rocket mode, utilising onboard liquid oxygen and hydrogen for its final climb to orbit.

The core enabler of this incredible capability is SABRE's pre-cooler technology. This innovative heat exchanger is capable of chilling superheated air entering the engine at hypersonic speeds (which can reach temperatures of around 1,000°C) down to -150°C in a mere fraction of a second. This rapid cooling is crucial because it allows conventional jet engine components to operate safely at speeds far beyond their normal limits, overcoming the extreme heat challenges posed by shock heating and surface friction at hypersonic velocities. Successful ground tests have already demonstrated this pre-cooler's integration with conventional jet engines.

While Reaction Engines ceased operations in 2024, the invaluable expertise and patented technology live on. Frazer-Nash Consultancy, the lead for INVICTUS, has wisely recruited many of Reaction Engines' top engineers, ensuring that this critical knowledge from over a decade of propulsion research and development is retained and advanced.

INVICTUS: Paving the Way for Future Spaceplanes

The INVICTUS experimental aerospace vehicle will be primarily powered by a hydrogen-fuelled precooled air-breathing propulsion system, directly proving the suitability of this technology for horizontal take-off and sustained hypersonic flight. This approach is poised to revolutionise access to space by enabling reusable launch vehicles that operate much like conventional aircraft, taking off horizontally from a runway. Such vehicles could deliver the same payload to orbit with half the vehicle mass of current launchers, potentially offering significant cost reductions and higher launch rates.

The INVICTUS consortium, spearheaded by Frazer-Nash, includes industry heavyweights like US aircraft maker Spirit AeroSystems and Britain's Cranfield University, alongside other small-to-medium enterprises. Their immediate goal over the next 12 months is to deliver the preliminary design of the full flight system.

Strong Backing from ESA and UK Space Agency

This ambitious endeavour is significantly supported by major space agencies:

• European Space Agency (ESA): ESA, through its General Support Technology Programme (GSTP) and Technology Development Element (TDE), has invested €7 million into INVICTUS. This builds on its previous investment of over €10 million in the development of the SABRE engine itself, and its long-standing technical oversight role. Mark Ford, Head of ESA’s Chemical Propulsion Section, emphasizes that INVICTUS is a "unique asset for exploring this type of flight" and an "important next step in developing the technologies required for future spaceplanes". Tommaso Ghidini, Head of ESA’s Mechanical Department, further states that "hypersonic flight is not just the next frontier of aerospace – it is the gateway to a new paradigm of mobility, defence, and space access".
• UK Space Agency (UKSA): The UKSA has been a pivotal supporter, having invested £50 million in SABRE development, in addition to collaborating with ESA. Tony Forsythe, Head of Space Technology at the UK Space Agency, highlights the project's "significant potential to build on advanced cooling and hypersonic propulsion technology developed by UK engineers over many years," noting the opportunity it presents for "boosting economic growth and national security". This support aligns with the government’s modern industrial strategy, aiming to put the UK at the forefront of pioneering aerospace technologies and ensuring its prosperity in the new commercial space age.

Beyond Space: Dual-Use Applications and Future Prospects

The underlying technology driving INVICTUS, born from SABRE, offers significant dual-use innovation. It promises to redefine both terrestrial and orbital transportation. Reaction Engines’ pre-cooler technology is already attracting attention from other sectors, with potential applications in:

• Sustainable Aviation: Incorporating heat exchangers into zero-carbon aircraft designs, particularly for managing heat from hydrogen fuel cells.
• Battery Thermal Management: Developing effective cooling systems for battery cells in electric cars and other applications.
• High-Speed Flight (Terrestrial): Augmenting existing jet engines to enable higher speeds and managing extreme temperatures for various high-Mach and hypersonic platforms. This includes military applications and potentially revolutionising global travel, with prospects like a London to Sydney trip reduced to just four hours.

While the original vision of a single-stage-to-orbit (SSTO) Skylon spaceplane faces ongoing technical challenges, the developers are exploring a pragmatic pathway towards a two-stage-to-orbit system, potentially featuring a highly reusable first stage operating in a horizontal take-off and landing configuration, with a more expendable upper stage for the final push to orbit.

This pioneering INVICTUS programme, backed by substantial investment and leveraging advanced SABRE technology, positions Europe and the UK at the cutting edge of aerospace. It not only promises to make space access more efficient and affordable but also to open new frontiers in high-speed global mobility and defence. The journey to a future where aircraft take off like planes and reach orbit like rockets has truly begun.



Alignment of Invictus with the UK's Strategic Plans for Spaceports

The INVICTUS programme is directly aligned with the UK's goals for its spaceports and broader space strategy by focusing on horizontal take-off and landing (HTOL) reusable launch vehicles [Blog Post, 24, 37, 50, 70, 161]. This capability is a key differentiator that complements the development of UK spaceports.

Here's how INVICTUS relates to the UK's space goals:

• Enabling Horizontal Space Launches from UK Spaceports:

• The INVICTUS programme aims to develop a reusable experimental aerospace vehicle capable of flying at Mach 5, with its first flight targeted by early 2031 [Blog Post, 69, 70]. This vehicle is specifically designed to prove the suitability of a hydrogen-fuelled precooled air-breathing propulsion system for horizontal take-off and hypersonic flight.
• Unlike most rockets, this spaceplane is designed to take off horizontally from a runway, akin to a conventional aircraft [Blog Post, 24, 37, 50, 70, 161]. This directly leverages the infrastructure and operational model of runways at developing UK spaceports.
• The lightweight architecture of a SABRE-like engine (which INVICTUS builds upon) paves the way for "true spaceplanes" capable of horizontal take-off, bringing the UK "a step closer to widespread access to space".

• Reducing Reliance on Foreign Launch Providers and Increasing Resilience:

• The UK Space Agency actively supports the creation of UK spaceports and native launch providers as a "game changer" for the national space industry.
• The aim is for the UK to no longer rely on other countries, such as Russia or French Guiana, for launching polar orbiting satellites.
• By developing capabilities like INVICTUS, the UK aims to have "more resilient launch alternatives, reducing its reliance on foreign launch service providers for access to space". Reaction Engines (whose technology underpins INVICTUS) was seen as having "some key differentiators including significantly more novel technology compared to the other UK launch systems under development".

• Boosting Economic Growth and National Security:

• Tony Forsythe, Head of Space Technology at the UK Space Agency, explicitly states that the INVICTUS project has "significant potential to build on advanced cooling and hypersonic propulsion technology developed by UK engineers over many years," presenting an opportunity for "boosting economic growth and national security" [Blog Post, 20, 76, 353].
• INVICTUS is viewed as a "dual-use technology initiative," aiming to deliver transformative advances across propulsion, advanced materials, and autonomous systems, benefiting both defence and commercial sectors.
• The UK government's "modern industrial strategy" aims to place the UK at the "forefront of pioneering aerospace technologies and ensuring its prosperity in the new commercial space age" [Blog Post, 6]. The INVICTUS programme contributes to this by establishing a "UK-led, reusable hypersonic test platform" that positions the UK and Europe at the forefront of next-generation aerospace innovation.

• Fostering Innovation and High-Skilled Jobs:

• The UK Space Agency's broader goals include fostering "innovative businesses and high-skilled jobs across the country, enhancing research development and productivity". INVICTUS, by leveraging the expertise of Reaction Engines' former engineers now at Frazer-Nash Consultancy, retains "vital knowledge from a decade of propulsion R&D and experimental testing" within the UK [Blog Post, 23, 351, 71].
• Reaction Engines, before its cessation, had significantly grown its workforce, employing highly skilled engineers, and contributing to knowledge spill-overs within the UK economy. The INVICTUS programme continues this legacy.

In summary, INVICTUS's development of a horizontal take-off, reusable spaceplane directly supports the UK's vision for its spaceports, enabling sovereign launch capabilities, fostering economic growth and national security through advanced aerospace technology, and positioning the UK as a leader in the next generation of space access and high-speed flight.