The supersonic combustion ram engine can get oxygen from the atmosphere during the ascent. Giving up carrying oxidants, obtaining oxygen from flight, and saving weight mean that under the condition of consuming the same mass of propellant, a super-combustion stamping engine can produce 4 times the thrust of a rocket.
As the application of 3D printing technology matures, 3D printed supercombustion stamping engines have become the focus of force of engine manufacturers in major military fields.
Challenging technical bottlenecks
In June 2019, U.S. weapon developer Raytheon announced that it has partnered with Northrop Grumman to develop a weapon called the aspirated hypersonic concept (HAWC), and the products of the two companies are ready for cooperation. The first flight, of which Noble was responsible for the manufacture of super-combustion ram engines, and Thor was the aircraft.
Northrop Grumman intends to manufacture all parts of the super-combustion stamping engine completely by 3D printing, which will be the first case in the world.
According to Raytheon, a super-combustion ram engine compresses air into the combustion chamber at high speed, which allows the aircraft to maintain a speed of more than 5 times the speed of sound for a long time. The positioning of this hypersonic weapon is aspirated. It is an aircraft using a super-combustion ram engine. It is basically consistent with the principle of the X-51A tested by the US Air Force a few years ago. Air intake, which is the technical bottleneck of super-combustion ram engines.
Competitors to the current HAWC plan include Raytheon and Nogg, as well as Lockheed Martin. The HAWC plan mainly addresses three key technical issues: the feasibility, effectiveness, and affordability of the aircraft. The technologies involved include advanced hypersonic aircraft configurations, hydrocarbon-propelled thrusters for sustainable hypersonic cruises, technologies that handle thermal stress during high-temperature cruises, economical design and manufacturing methods, and more.
The HAWC operation method is to first accelerate the rocket engine to at least Mach 4 and then use a high-speed super-combustion stamping engine to push the speed between Mach 5 to 10 for super high-speed cruising. The difference from a ballistic missile is that it can maneuver in the atmosphere, making it more difficult for the defending party to predict its flight path and therefore more difficult to defend.
The AGM-183A air-launched hypersonic missile was tested on the B-52 bomber in June 2019. Interestingly, the AGM-183A was originally developed by Lockheed Martin, led by DARPA in the early days, and then executed by the US Air Force. The tactical idea is to use rockets to boost into sub-orbits and complete long-range gliding strikes. The maximum flight speed can reach Mach 20.
What can be clearly seen is that the cooperation in the development of aspirated hypersonic aircraft means that Thor and Knoll have joined forces to fight against Loma.
Coincidentally, just in June of this year, Aerojet Rocketdyne announced that its new hypersonic engines manufactured for NASA and the Defense Advanced Research Projects Agency (DARPA) have successfully passed testing.
Aerojet Rocketdyne supersonic propulsion technology has been accumulated for more than 30 years, and Aerojet Rocketdyne's super-combustion stamping engine has powered the record-setting X-51A WaveRider test.
As early as 2016, U.S. military giant Orbital ATK announced that the company successfully tested 3D printed hypersonic engine combustion chambers at the NASA Langley Research Center. The 3D printed hypersonic engine combustion chamber not only meets or exceeds all performance requirements, but also creates a wind tunnel test record that can withstand the longest duration of propulsion in similar equipment, marking the further advancement of supersonic aviation technology.
According to the market observation of 3D Science Valley, the British Reaction Engines company is also designing and developing a new generation of innovative supersonic propulsion system SABRE, which also uses 3D printing technology. SABER is a hybrid engine capable of flying at low and high altitudes. A major breakthrough in the development of this hybrid engine is Reaction Engines' proprietary heat exchanger technology, which prevents icing propellant injectors during this heat exchange process The system is manufactured using 3D printed additive manufacturing technology. The SABRE engine boosted the aircraft's speed to Mach 5.4 (more than 6000 km / h) or even Mach 25 by inhaling oxygen from the atmosphere, then switched to hydrogen fuel and used built-in liquid oxygen. In order for the engine to work in extreme atmospheric conditions, it needs to be able to reduce the air flow drawn into the engine from over 1000 ° C to minus 150 ° C in less than one hundredth of a second. The SABRE engine does just that and the engine adds very little weight.
In addition to the application of metal 3D printing technology in hypersonic propulsion systems, according to the market observation of 3D Science Valley, high-temperature ceramic 3D printing technology is also a key area of breakthrough in the field of supersonic aircraft manufacturing. At present, very few materials can withstand the extreme heat and pressure generated during supersonic flight, and 3D printed high-temperature ceramics may be the solution to this problem. In 2016, the United States HRL Laboratory announced a new technology developed by it, which uses 3D printed super-ceramic materials that can withstand temperatures of more than 1,400 degrees Celsius. HRL Lab's research has made new progress with the support of NASA's space technology research funding. NASA's funding has promoted the development of HRL in the field of 3D printed rocket engine parts made of temperature-resistant ceramics. HRL can currently 3D print two types of ceramics. One is a large, very lightweight lattice structure that can be used for heat-resistant plates and other external components in aircraft and spacecraft. One is the small but complex parts of electromechanical systems or components used in jet engines and rockets.
In general, the combination of 3D printing technology and hypersonic space engine manufacturing experience lays the foundation for the development of the next generation of hypersonic propulsion systems.