When Jet Power and Rocket Power Combine…

Imagine boarding a plane to travel halfway around the world—a journey that would take about 20 hours in a 747.  But you reach your destination in a mere four hours, thanks to a hypersonic flight traveling at speeds in excess of Mach 5.

This may sound like science fiction, but such travel will soon be an economical reality powered by SABRE engines. 

SABRE™ —Synergetic Air Breathing Rocket Engine—is a new class of engine under development for propelling both high-speed aircraft and spacecraft. SABRE engines are unique in delivering the fuel efficiency of a jet engine with the power and high-speed ability of a rocket.

Unlike jet engines, which are only capable of propelling a vehicle up to Mach 3, three times the speed of sound, SABRE engines are capable of Mach 5.4 in air-breathing mode—for traveling around the globe, and Mach 25 in rocket mode—allowing orbital access.

What’s more, SABRE’s blend of traditional jet engine mechanics and rocket propulsion allows for horizontal take-off and landings, enabling future spaceports to accommodate the next generation of aircraft and spacecraft. And, while most rockets are good only for a single use, SABRE’s unique design permits it to come back to Earth to power another flight—again and again.

Invention = Not Just Product, but Process

Central to the SABRE design is the breakthrough in aerospace engine technology Reaction Engines has achieved by developing ultra-lightweight heat exchangers (pre-cooler), which stop engine components overheating at high flight speeds.

The journey to this ground-breaking technology began many years ago in the mind’s eyes of a few R&D experts at Reaction Engines. But before the true wizardry could begin, these visionary inventors needed to design a prototype to prove the possibility of an entirely new method of propulsion.

The first step was identifying ultra-lightweight yet strong metals and materials, then determining how to join them together. This one-of-a-kind engine would require metals with a dramatically different metallurgy and an extraordinary thermal cycle to prepare those materials to withstand extreme circumstances. Through more than 700 tests, the SABRE inventors proved out their principles while defining—and refining—the meticulous process needed to produce a viable engine concept.

Innovation in Epic Proportions

As Reaction Engines calculated the process and equipment required for this undertaking, one thing became clear. Manufacturing the engine’s pre-cooler—a complex system of ultra-fine but incredibly robust metal tubes—would require a highly specialized furnace: one that could precisely control a meticulous brazing process to succeed with a decidedly unique form, geometry and metallurgy.

SABRE will consist of three key elements: the pre-cooler, the engine core, and the thrust chamber. The pre-cooler, essential to achieving speeds of Mach 5 and greater, is composed of thousands of thin-walled tubes that carry coolant. It’s an intricate system: Approximately two thousand kilometers of microfine tubing, with wall thicknesses half the width of a human hair. And every joint must be hermetically sealed, enabling the pre-cooler to reduce air temperature from 1,000° C to -150°C in a fraction of a second. This process pulls energy from the air at a rate of approximately 400 MW —the equivalent of a small power station!

After outlining precise specifications, identifying optimal materials and metallurgy, and mapping out a never-before-attempted thermal process, Reaction Engines turned to Consarc, an Inductotherm Group company. With a half-century of experience in vacuum and controlled atmosphere melting, Consarc was the only partner capable of designing and manufacturing a custom furnace to satisfy this customer’s extraordinary needs.

In addition to decades of valuable expertise, UK-based Consarc offered a robust R&D team, staff engineers, technical consultants and installation experts to design custom furnace technology to meet Reaction’s specific, unprecedented requirements. Everything about the furnace, from its vacuum capability to its temperature control, was precisely calculated with virtually no margin for error to ensure exact, repeatable results—something no existing furnace could come close to doing. Something only a true master of the trade could accomplish.

And so, a project that began as a small team experiment at Reaction Engines grew six-fold, as the Consarc team of professionals identified and presented several possible solutions. As plans for the furnace grew, so did its group of experts; the engineering, manufacturing and installation teams at Consarc’s UK facility all played a critical role in the design and construction of Reaction’s custom equipment.

The result of their collaboration is a one-of-a-kind furnace that can quickly and accurately heat and cool modular assemblies containing large quantities of extremely delicate tubing—all within highly controlled and consistently repeatable conditions. The furnace’s hot zone charge size is one of the largest of its kind in the world, measuring 2.5m in diameter and 1.5m high. The sheer size ensures that the furnace will accommodate not only the pre-cooler’s test components, but also the sections that will ultimately comprise the full-scale production version of SABRE.

Proving Grounds

With a fully customized Consarc vacuum brazing furnace installed onsite, Reaction Engines spent several years refining the fastidious manufacturing process required to produce the heat exchanger technology which will be the fore-runner of the final SABRE pre-cooler.

SABRE’s modular design allows each component to be built and ground-tested independently. Testing of representative technology (known as HTX) will begin in late 2018 at a soon-to-be-completed test facility at Front Range Airport near Watkins, Colorado. Testing at this facility will simulate the high temperature airflow conditions SABRE will experience at Mach 5 and validate the performance of the pre-cooler technology.

At a separate testing facility also under construction in Westcott, Buckinghamshire, UK, the Reaction team will begin testing from 2020 to assess critical subsystems and the SABRE engine core. Once all these ground tests pass muster, the process will continue, to enable SABRE to take to the skies, powering a flight test vehicle and making aviation history.

The Sky is No Longer the Limit

Reaction Engines will revolutionize air travel. Powering the next generation of aircraft, from defense applications to commercial flights, SABRE will enable more efficient travel, reaching speeds twice that of today’s traditional jet engines. And, with its dual functionality, this new breed of engine will operate not just in Earth’s atmosphere, but beyond it—making access to space far more economical; which ultimately will underpin increasingly ambitious possibilities for space travel.

Learn more about the revolutionary SABRE at ReactionEngines.co.uk.

To find out how Inductotherm Group can help you bring heat to metal, visit InductothermGroup.com.