This British company builds engines that can run at breakneck speeds, in conditions that would melt today’s jet engines.

The firm wants to reach a hypersonic speed , that is, more than five times the speed of sound, around 6,400 km / h or Mach 5.

The idea is to build a high-speed passenger transport by the 2030s. ” You don’t have to go to Mach 5. It can be Mach 4.5, which requires easier physics,” says Dissel. At that speed, it could fly from London to Sydney in four hours or from Los Angeles to Tokyo in two hours.

However, most research on hypersonic flight is not for civil aviation, but originates from the armed forces of some countries, where there has been an explosion of activity in recent years.

Hypersonic aircraft would need new engine technology.

This British company builds engines that can run at breakneck speeds, in conditions that would melt today’s jet engines.

The firm wants to reach a hypersonic speed , that is, more than five times the speed of sound, around 6,400 km / h or Mach 5.

The idea is to build a high-speed passenger transport by the 2030s. ” You don’t have to go to Mach 5. It can be Mach 4.5, which requires easier physics,” says Dissel. At that speed, it could fly from London to Sydney in four hours or from Los Angeles to Tokyo in two hours.

However, most research on hypersonic flight is not for civil aviation, but originates from the armed forces of some countries, where there has been an explosion of activity in recent years.

“Systems zoo”

James Acton is a UK physicist working for the Carnegie Fund for International Peace in Washington DC.

Examining the US, Chinese and Russian efforts on hypersonic weapons, he concludes that “there is a whole zoo of hypersonic systems on the drawing board.”

Special materials that can withstand the extreme heat produced by speeds of Mach 5 , and a host of other technologies, make hypersonic flight possible in Earth’s atmosphere.

Experiments in piloted hypersonic flight date back to the American X-15 rocket plane of the 1960s.

Intercontinental ballistic missiles (ICBMs) also travel at hypersonic speeds when they re-enter Earth’s atmosphere.

Now, rival powers are striving to create weapons that can stay within the atmosphere, without using the cooling properties of outer space, and that can be maneuvered towards a target that could be moving, unlike a guided ICBM. to a city.

Difficult precision

Military spending is driving the hypersonic development of the three big players in the international sphere.

At a Pentagon press conference in March, Mike White , deputy director of hypersonic projects in the US military, spoke about the development of this technology driven by “our high-powered competitors and their attempts to challenge our dominance.”

One of the great challenges of these hypersonic missiles is precision. Hitting a nuclear-powered aircraft carrier traveling at 30 knots or more (56 km / h) requires fine adjustments to a missile’s heading that are difficult to achieve at speeds of Mach 5.

The heat generated around the surface of the missile traveling at hypersonic speeds creates a layer of plasma, or gaseous matter. This layer can block signals received from external sources, such as communications satellites, and can also blind internal targeting systems trying to locate a moving object.

Plasma only collects where the highest temperature is. A cone- shaped missile will have a uniform layer of plasma, but missiles that resemble darts can push that plasma screen away from surfaces that contain the most sensitive antennas.

As if hypersonic flight wasn’t difficult enough, chemical dissociation adds to the problems. At extreme speeds and temperatures, this phenomenon causes oxygen molecules to break down into their constituent atoms. This in turn complicates the chemical model on which any air-breathing engine is based.

Five minute flight

But progress in the hypersonic arms race has been spectacular.

In 2010, the United States flew a drone across a stretch of the Pacific Ocean at hypersonic speeds for five minutes.

The goal was more than speed, it was time. Five minutes may not sound like a long flight time, but in terms of defeating hypersonic barriers it was a triumph.

This speed machine, the X-51A, was launched from a high-flying B-52 bomber and used a rocket booster to reach a speed of Mach 4.5 before its main engine kicked in.

This main engine, known as a scramjet, combined the blast of air with jet fuel to accelerate to hypersonic speeds.

That meant dealing for several minutes with the air temperature entering 1,000 ° C. Finally, four X-51As made a one-way trip over the Pacific between 2010 and 2013.

Shock waves

Aerojet Rocketdyne is a California company specializing in rocket and space engines that worked on the X-51A.

Its staff only speak on condition of anonymity, even seven years after the project ended, which shows the reserve surrounding this technology.

An expert in hypersonics at the firm says of the X-51A: “The really hot part of the machine is in the front end where the shock waves are formed, so that’s where the investment in materials goes.”

He adds that much was learned from the X-15 rocket plane of the 1960s and from NASA’s subsequent space shuttle program.

The British company Reaction Engines has developed a process that should allow its aircraft engine to ingest superheated hypersonic air without incident.

Your Saber engine incorporates what you call a “pre-cooler.” This is the first part of the engine that encounters hot and angry hypersonic air.

The challenge then is to mix this air with fuel to create thrust.

As hot as lava

The Saber engine underwent an intensive test regimen at a Colorado site in October 2019, during which Reaction Engines had to find a way to replicate hypersonic air speeds.

The company used a supersonic engine to channel the air that came out of its rear end into the intake of the Saber engine.

Saber’s pre-cooler did its job, introducing coolant into the system at high pressure and allowing Saber to mix that air with fuel.

The materials required here are not simple.

One option is to use a nickel alloy called Inconel that can cope with a flow of air as hot as lava.

Dissel says that Reaction Engines is now going this Inconel alloy route. “We are on that right now, and also testing cooling channels to mine heat,” he says.

So a sophisticated thermal management system coupled with the use of Inconel point the way forward.

Hypersonic leaders

If this combination works, the vision of carrying commercial passengers on a hypersonic flight could become a reality within 15 years.

The US Air Force unit dealing with presidential jets has seen the potential of hypersonic travel to allow VIP passengers to arrive with maximum impact.

It has commissioned Hermeus, a startup based in Atlanta, USA, to evaluate a transportation design that travels at a speed of Mach 5 and that can carry up to 20 passengers.

This means that in the future, the president of the United States could join a very select group of Mach 5 travelers.