The UK government has announced that it is ready to invest 60 million pounds (almost 3 billion rubles) in the project of the private company Reaction Engines. The company's engineers expect to build a working model of a brand new commercial jet engine. This engine will be named Saber, an abbreviation for Synergetic Air-Breathing Rocket Engine. At present, laboratory tests of prototypes of the new engine have already been successfully completed, which has become an additional incentive for the state to invest in this project.
An airplane based on Saber engines will be able to reach the stratosphere in just 15 minutes, and cover the distance, for example, from Australia to the United States in just 4 hours. The speed of such an aircraft would exceed the speed of sound by a factor of 5 at once. Currently, Reaction Engines plans to equip their famous Skylon aircraft with a new engine, which could potentially accelerate to 5635 km / h. According to representatives of the British company, Skylon has every chance to become a real "spaceship" and fly in low earth orbit.
Traditional engines, which are used in aviation today, require the transport of special tanks filled with liquid oxygen if the aircraft reaches a speed of more than 3000 km / h in flight. Such planes cannot "breathe" ordinary air, as it would heat up to very high temperatures. At the same time, the Saber engine allows the use of air instead of liquid oxygen: it is equipped with a whole system of tubes that are filled with helium. As air passes through these tubes, helium cools it down and oxygen of the required temperature (-150 degrees Celsius instead of the original 1000 degrees) is delivered directly to the engine.
Developed by Reaction Engines, the Saber engine is able to operate in 2 modes: as a jet engine and as a rocket engine. According to company representatives, the use of this engine on the Skylon aircraft will allow it to be 5 times the speed of sound in the Earth's atmosphere and 25 times in outer space. The key element of this engine, which will allow it to work effectively within the atmosphere, is the precooler, in which the incoming outside air with a temperature of about 1000 degrees is cooled to a temperature of -150 degrees in just one hundredth of a second.
Once the Skylon enters space, it can be put into what is called "space mode". In this case, the aircraft will be able to stay in low-earth orbit for 36 hours. This time is more than sufficient, for example, to launch a satellite. Moreover, it will be a very profitable technology. According to Alan Bond, who is the founder of the company, the amount required for launching satellites and other similar missions could be immediately reduced by 95% if the commercial production of Saber engines is established.
In addition, new spacecraft built on air-jet engines can become a very good prospect in the space tourism market. In this case, the British firm Reaction Engines could become a very strong competitor for Virgin Galactic, which belongs to Richard Branson. Now the billionaire invites everyone to see our planet through the window for only 121 thousand pounds (almost 6 million rubles). Representatives of the Reaction Engines company say that the flight on their Skylon spacecraft will cost space tourists significantly less, however, they do not yet say how much. More details about the plans of the UK government regarding funding for this ambitious project will become known when a special UK Space Conference is held in Glasgow.
History of appearance
The idea of designing a precooled engine first came to Robert Carmichael back in 1955. This idea was followed by the idea of a liquefied air engine (LACE), which was originally developed by Marquardt and General Dynamics in the 60s of the last century, as part of the US Air Force's work on the Aerospaceplane project.
However, work on the project of a new Saber engine started only in 1989, and this year Reaction Engines Limited was formed. The company's specialists continued to work on the project, developing the ideas presented earlier. As a result, the creation of the Saber hybrid engine took 22 years from a research team of 30 people. The fruit of their efforts was the construction of a mock engine, which was installed on the Skylon aircraft, which was on display at the Farnborough Air Show.
The latest tests carried out by Reaction Engines have focused on air pre-cooling technologies. At present, the specialists of this company, having a workable technology in their hands, are developing a prototype of the cooling system. This specimen should be comparatively light in weight and also exhibit aerodynamic stability, high mechanical strength, and resistance to strong vibration. According to the company's plans, tests of a prototype cooler were to begin in August 2012.
By November 2012, Reaction Engines had completed equipment testing under the Heat Exchanger Technology Critical for Air / Liquid Oxygen Powered Hybrid Rocket Engine. This was a very important stage in the process of creating a hybrid engine, which proved to all potential investors in the project the viability of the technologies presented. The Saber engine is based on a heat exchanger that is able to cool the incoming air down to -150 ° C (-238 ° F). In the process of operation, cooled air is mixed with liquid hydrogen, after which, burning, it provides the necessary thrust for atmospheric flight, before switching to liquid oxygen from the tanks, when flying outside the earth's atmosphere. Successful tests of this rather critical technology have confirmed in practice that the heat exchanger is able to meet the needs of a hybrid engine to obtain the required amount of oxygen from the atmosphere to function with high efficiency in low-altitude flight conditions.
At the 2012 Farnborough Air Show, David Willets, UK's Secretary of State for Universities and Science, praised the development. In particular, the minister said that this hybrid engine can have the most real impact on the conditions of the game that have formed today in the space industry. The successful tests of the engine pre-cooling system confirmed the high appreciation of the proposed concept, which was made by the UK Space Agency in 2010. The minister also noted the fact that if one day they manage to apply this technology to organize their own commercial flights, then this will undoubtedly become a fantastic event in scale.
David Willets also noted the fact that there is little likelihood that the European Space Agency will agree to fund the Skylon project. For this reason, Great Britain must be prepared for the fact that it will have to deal with the construction of the spacecraft, for the most part with its own funds.
Performance
The design thrust-to-weight ratio of the Saber hybrid engine is expected to be more than 14 units. It should be noted that the thrust-to-weight ratio of ordinary jet engines is within 5 units, and only 2 units for supersonic ramjet engines. This high level of performance has been achieved through the use of supercooled air, which becomes very dense and requires less compression, and even more importantly, due to the low operating temperatures, it is possible to use sufficiently light alloys for most of the hybrid engine design.
The engine has a high specific impulse in the atmosphere, which reaches 3500 seconds. For comparison, an ordinary rocket engine has a specific impulse, which is about 450 seconds at best, and even a "thermal" nuclear rocket engine, which is considered promising, promises to reach a magnitude of only 900 seconds.
The combination of low engine mass and high fuel efficiency gives the promising Skylon aircraft the ability to reach orbit in a single-stage mode, while the engine operates as an air-jet engine up to a speed of M = 5, 14 and an altitude of 28.5 km. At the same time, the aerospace vehicle is able to reach an orbit with a very large payload relative to the take-off weight of the aircraft itself. That previously could not be achieved by any conventional aircraft.
Engine advantages
Unlike its traditional rocket cousins, and like other types of jet engines, the new British hybrid jet engine can use air to burn fuel, which reduces the required weight of propellant, while increasing the weight of the payload. A ramjet engine (ramjet engine) and a hypersonic ramjet engine (scramjet engine) must spend a sufficient amount of time in the lower atmosphere in order to develop a speed sufficient to enter orbit, which in turn brings to the fore the problem of intense heating engine at hypersonic speed, as well as possible losses due to the complexity of thermal protection and significant weight.
At the same time, a hybrid jet engine like the Saber only needs to achieve a low hypersonic speed (it is worth recalling that hypersonic is everything after M = 5) in the lower layers of the Earth's atmosphere, before switching to a closed cycle and making a steep climb from acceleration in rocket mode.
Unlike traditional ramjet or scramjet engines, the new British Saber engine is able to provide high thrust from zero speed to M = 5, 14 inclusive, throughout the entire altitude range, with very good efficiency over the entire altitude range. In addition, the ability to create thrust even at zero speed indicates the possibility of testing the hybrid engine on the ground, which significantly reduces the development cost.
Assumed characteristics of the Saber engine:
Thrust at sea level - 1960 kN
Void thrust - 2940 kN
Thrust-to-weight ratio - about 14 (in the atmosphere)
Specific impulse in vacuum - 460 seconds.
Specific impulse at sea level - 3600 seconds.
