Friday, May 5, 2017

Britain's Incredible Sabre Engine That Will Make Orbital Space Planes Common Place

A space engine that could make flying into orbit commonplace

        Britain’s ‘rocketeers’ move closer to turning a near 30-year dream into reality Read next Engine could boost UK’s space ambitions Share on Twitter (opens new window) Share on Facebook (opens new window) Share on LinkedIn (opens new window) Email4 Save YESTERDAY by: Peggy Hollinger, Industry Editor The tiny metal tubes that sit at the heart of the Sabre engine seem too fragile to bear the weight of Britain’s space ambitions. With walls half the thickness of a human hair, they will snap if bent too far.  Laid in sheets of overlapping spirals at the front of the engine they are the conduits of a unique air cooling system that could one day make flying to space and back again as commonplace as taking a flight from London to New York.  On the shop floor of Oxfordshire-based Reaction Engines, Simon Hanks, head of advanced manufacturing, holds up one of the tubes, hardly wider than a piece of string. “What we do with this, to turn it into something like that,” — he points to the pre-cooler that can chill air from 1,000 degrees Celsius to minus 150 degrees in one 100th of a second — ‘that is the magic’.”  Reaction Engines has spent almost 30 years getting that magic to work, developing an engine concept that combines both conventional jet engine technology and rocket propulsion. Founded in 1989 by a group of engineers known as the “three rocketeers”, Alan Bond, Richard Varvill and the late John Scott-Scott gave up their day jobs to pursue their dreams of space travel. This is the year that their dream begins to become reality. The company on Thursday announced plans to invest £10m to build its first proper ground test facility at Westcott, which for 70 years has been the home of British rocket research. This is a milestone development, one that marks the end of the experimental phase and the start of proving the Sabre concept.  “It is a big moment in the programme, says Mark Ford, head of propulsion engineering at the European Space Agency, which is administering some of the UK’s £60m investment in Sabre technology. “The stopwatch has started now. This is where we prove all the principles that Reaction has been saying. When that is done we can say this is very much a new type of engine.”  The Sabre engine was conceived by the               Three Rocketeers in tandem with a space plane, Skylon, to take an aircraft from earth to orbit and back again in a single stage, with no parts jettisoned in flight. However, under Mark Thomas, chief executive since 2015, the company will focus on the engine and move towards its ultimate goal of single-stage-to-orbit propulsion in steps. This means developing an intermediate solution to make the first stage of traditional two-stage launches more efficient. 1. Atmospheric air enters the engine and is pre-cooled by passing through a heat exchanger. 2. The resulting energy is transferred into a helium loop that powers engine components, reducing fuel consumption. 3. The cooled air is now compressed without becoming so hot it destroys the engine. 4. Some of this compressed air is burnt with liquid hydrogen in the pre-burner, which adds more heat to the helium loop as it drives the compressor and hydrogen pump. 5. The rest of the air is burnt with the pre-burner exhaust in the thrust chambers. 6. Excess hydrogen not burnt in the main engine is bled to the ramjet burners where it is burnt with excess air to create extra thrust. Reaction has also cut the size of the engine under development by three-quarters and brought in BAE Systems, which injected £20.6m in exchange for a 20 per cent stake. The impetus is a rising demand for lower cost re-usable satellite launch systems. Euroconsult, a global consulting company, estimates that some 9,000 satellites will be launched into orbit in the 10 years to 2025, against fewer than 1,500 in the previous decade.  The advantage of scaling back ambitions in the near term, Mr Thomas says, is that this market can be accessed more quickly and the initial costs of development are significantly lower. Now capable of being used in modular scaleable configurations, the technology can also be applied to a greater range of sectors to help generate revenue earlier. “Single stage to orbit, full re-usable systems are the ideal state, the Holy Grail,” he says from the company’s headquarters at the Culham Science Centre near Abingdon.         “But there has to be something between the two. Single stage to orbit is still on the road map. “But we have pushed the horizon out slightly further, partly to enable us to exploit these earlier opportunities that we have seen through dialogue with government and industry.”  1. The centre body moves forward, closing off the air intake and shutting down the compressor. 2. Oxygen is now supplied to the engine from the internal tank rather than externally. 3. Heat from the rocket pre-burner exhaust drives the fuel pumps and thrust is created in the same way by . . . 4. . . . burning liquid oxygen and pre-burner exhaust products in the thrust chambers. Industry experts say Reaction’s strategy make sense — especially for a concept as ambitious as the Sabre engine. Reaction “is the only one in town doing this type of engine”, says Phil Smith of US-based Bryce Space and Technology consultants. “This iterative process is a very wise way to go. It demonstrates a maturity in the industry that didn’t exist before.” Rather than focusing on a goal that might fall victim to funding constraints, Reaction is seeking to demonstrate the utility of its innovation in more immediate ways, he says.  Meanwhile, the Westcott facility is only the first of several milestones this year. While the foundations are being laid, Reaction will start building its first demonstrator engine to be fired up in the new test centre in 2020. Later this year the pre-cooler will be tested under the same intense temperature conditions that it will experience in hypersonic flight.  To gain access to a hypersonic wind tunnel capable of generating the necessary airflows of five times the speed of sound or more, Reaction is talking to the US government, which is interested in the technology for military use and for its space programmes. The US Air Force Research Lab has validated the concept and told the Financial Times that it was “keeping an eye on [the] Sabre ground-testing progress”.  A US partnership will bring new funding to a programme likely to cost billions before it is actually flown on the wing of an aircraft — a milestone at least a decade away. It could also open up a vast new market to Britain’s most promising space start-up.  Engine could boost UK’s space ambitions Play video “US government interest and funding . . . could be, strategically, very important for us and for the UK,” says Mr Thomas. “We see it as a strategic objective.”  Yet, working with the US government may also raise concerns that the UK is giving away cutting edge technology for others to exploit.  Mr Thomas insists, however, that Reaction is fully aware of the need to protect the benefits of its innovation for the UK. “We have to assure ourselves that we are not going to leak technology or know-how through that activity,” he says.  In the meantime, Reaction is hoping its pre-cooling technology will draw interest from sectors such as commercial aerospace, power generation or automotive. It could launch a new product as early as next year, says Tom Scrope, finance director.             “Some of the institutional investors have expressed an interest that if we come up with a proposition to spin out technology on a non-competing basis they would look to fund that on a standalone basis,” says Mr Scrope. “We are looking to monetise this technology in the nearer term.”  The 'Three Rocketeers': The brains behind the technology that could revolutionise flying into space - Alan Bond, left, Richard Varvill and the late John Scott-Scott in a photograph taken at the start of their journey The challenge for Reaction will be to do that while maintaining its focus on the longer term goal of single stage to orbit, which promises to put Britain at the forefront of a space industry that could be worth some £400bn by 2030. The surviving Rocketeers are confident that the new strategy will not jeopardise their original dream. “The size we are looking to demonstrate is right in the sweet spot of a number of applications,” says Mr Varvill, today Reaction’s chief engineer. “If we think of [Sabre] as a module then we are still on the road to Skylon.” Sabre: the ‘Holy Grail’ in space technology Researchers have spent decades trying to crack the problem of how to fly from earth to space and back again, writes Peggy Hollinger. But it took a combination of rocket and nuclear science to make the breakthrough that is now drawing interest from around the world in Reaction Engines’ Sabre technology. “It was pretty clear that the rocket needed a bit of a leg up and the only place to get that was from the Earth’s atmosphere,” says Alan Bond, one of Reaction Engines’ three founders. “But the [speed] you get out of conventional jet engines isn’t enough. Somewhere in 1982 . . . I realised that a bit of theory I had used on nuclear engines 10 years before could actually help. So the hybrid air-breathing rocket engine came into existence.” The engine combines jet and rocket technologies thanks to its unique pre-cooler, which extracts heat from air flowing in at high speeds of up to Mach 5 — several times the speed of sound. This enables it to be used by the engine, which then uses the heat energy to power a turbocompressor. When at the edge of the atmosphere, the engine switches into rocket mode, using liquid oxygen to break through into orbit. Unlike partially re-usable launchers being developed by the likes of SpaceX of the US, Sabre does not need to carry large quantities of liquid oxygen, and will not have to discard stages of the craft during flight. It could be what the industry describes as the “Holy Grail” — a single stage to orbit system. 

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