Application of aluminum in launch vehicle
West Aluminum - West Aluminum Industry Telecom: Aluminum has become a very important key material in launch vehicle, because aluminum alloy has low density and excellent low temperature performance. The liquid hydrogen liquid oxygen fuel tank of launch vehicle is made of aluminum alloy, and the material used for main structure of cabin is aluminum alloy. Now the carrier rocket structural materials have entered the fourth generation, namely, the age of 2-Series and 5-series alloy with a small amount of Li. The main alloys are 2195, 2196, 2098, 2198 and 2050. China has a big gap in developing Aerospace Al Li aluminum alloy compared with foreign countries, but it can catch up with or surpass them in an all-round way around 2025, and become the world leader.
Because of its low density (< 2.8g/cm3), high specific strength and specific stiffness, corrosion resistance, fatigue resistance, toughness, processing and molding properties, it is an industrial metal with abundant resources, moderate price, harmless to human body and environment and cyclic performance, so it has been widely used in various departments of national economy, and has become the second largest metal in 2020, The production of raw and recycled aluminum is about 95000kt worldwide, which is an indispensable material from daily necessities to aerospace. In the present materials of carrier rocket structure, aluminum and aluminum based composite materials are used as a kind of materials. According to the author's estimation, the net mass of aluminum and aluminum alloy accounts for more than 85% of the total net mass of the structure in the structure and parts of the launch vehicle.
Storage tank structure
Structural materials are closely related to a series of problems such as structural design, manufacturing and processing technology, material preparation technology and economy, which is the key to determine the takeoff quality and payload capacity of rocket. According to the development of material system, the development process of rocket fuel tank materials can be divided into four generations. The first generation is 5-series aluminum alloy, namely Al Mg alloy, which is representative alloy 5A06 and 5A03. It has been used to manufacture the structure of P-2 rocket fuel tank in the late 1950s. 5A06 alloy contains 5.8% mg-6.8% Mg and 5A03 is an Al Mg Mn Si alloy. The second generation is Al Cu 2-Series alloy. The storage tank of Long March launch vehicle in China is made of 2A14 alloy, which is an Al Cu Mg Mn Si alloy; From 1970s to now, China has begun to manufacture tanks with 2219 alloy, which is an Al Cu Mn V Zr Ti alloy, which is widely used in the manufacture of various launch vehicle tanks. At the same time, the low temperature fuel tank structure of weapon launching has also been widely used, which is a kind of alloy with good low temperature performance and comprehensive performance; The third generation is Al Li alloy, i.e. 2-Series alloy and 5-series alloy with Li content ≤ 3.0%. The former is used by the United States, Britain, Germany, Japan, etc., and the latter is developed by Russia. It has been used abroad in 1980s, and has already entered the stage of industrialization preparation and Engineering application. At present, China has only a small scale application in aviation industry, No application case has been reported on the structure of the carrier rocket tank.
Long March 5 carrier rocket
On November 3, 2016, China successfully launched the Long March 5 launch vehicle, nicknamed "fat five". The diameter of the core is 50% larger than that of the Chinese active rocket, the diameter of core is 5m, the diameter of booster is 3.35M, while that of Chinese active rocket is 3.35M and the diameter of booster is 2.25m. In addition to the "waist" size, it is about 57M tall, equivalent to 20 stories high, second only to the Long March 2 F carrier rocket, and thus can accommodate more propellant (fuel). The core engine uses liquid hydrogen (-253 ℃) liquid oxygen (-183 ℃), and the booster fuel is liquid oxygen kerosene combination. That is, the temperature inside the Long March 5 is far lower than the ultra-low temperature of the ice point, so it is also called "ice arrow". 90 percent of the bodies that weigh more than 800 tons on Long March 5 are liquid hydrogen and liquid oxygen. After ignition, the temperature of the flame emitted by the engine is as high as 3000 ℃, at this time, the extreme state of "double sky" inside and outside the engine is a great test for Chinese aerospace technology and materials.
The development of Long March 5 lasted for 10 years, which shows that it is very difficult. In the development, 247 key technologies have been broken through, among which 12 of the most important key technologies have been made, with the proportion of new technologies reaching nearly 100%. All the core technologies are self-created, and the leapfrog upgrading and replacement of Long March rockets have been realized. The Long March 5 rocket has 12 "big hearts" or engines, providing a total thrust of 10564.4kn. Eight liquid oxygen kerosene engines are 4 groups, which are composed of booster power, with a total takeoff power of 9408kn; Two 490kn hydrogen oxygen engines are responsible for the primary power of the core and 980kn for takeoff; Two 88.2kn expansion cycle hydrogen oxygen engines are composed of two-stage power. The low-speed launch capacity of Long March 5 launch vehicles can reach 25t and high-speed rail carrier capacity can reach 14T. It has crossed the "threshold" of the international large-scale launch vehicles' near earth orbit delivery capacity of 20t and high orbit delivery capacity of 10t. It can run alongside the world's major large rockets such as the United States cosmology God 5, delta 4 and European Arian 5.
Although China's launch vehicle industry has made remarkable achievements, there are still some gaps compared with the world aerospace powers. The spectrum of launch vehicle needs to be improved continuously. The key technical foundation such as rocket engine and large diameter rocket structure needs to be consolidated constantly. The new development mode of reducing cost and improving competitiveness needs to be established and strengthened.
The first flight of "one arrow and five stars" on the 8th Long March
At 12:37 on December 22, 2020, the first flight test of Long March 8, a new medium-sized launch vehicle independently developed by China, was successfully completed. The Long March 8 rocket has fully inherited the technical achievements of Long March 5 and Long March 7 launch vehicles, filled the gap of the launch capacity of 3t-4.5t in China's solar synchronous orbit, which is of great significance to accelerate the upgrading and replacement of launch vehicles.
The Long March 8 launch vehicle is about 50m long in length, adopting the modular assembly concept. In the future, the launch cycle of Long March 8 rocket will be shortened to 10 days, and the vertical takeoff and landing technology will be adopted to enable them to launch more than once. It is estimated that the system can be completed before and after 2025. China plans to build multi cabin and inhabited space station around 2022, In 2045, the total number of flights per year reached the order of thousand, the total freight reached 10000 tons, and the total passenger transport reached 10000.
Launch vehicle made of Xinan aluminum, a large forging ring in Tianjin
China launch vehicle manufacturing base is located in Tianjin Economic and Technological Development Zone, which is composed of rocket development and production zone, aerospace technology application industry zone and auxiliary supporting area. It integrates rocket parts production, component assembly, final assembly test and test.
The rocket propellant tank is connected by a section of cylinder with length of 2m-5m. The tanks are made of aluminum alloy, so they are connected and reinforced by aluminum alloy forging rings. In addition, the connecting forging rings are also used for the connectors, transition rings, and transfer frames of launch vehicles, space stations and other spacecraft. Therefore, forged rings are a key connecting part and structural part. Southwest Aluminum (Group) Co., Ltd., Northeast Light Alloy Co., Ltd. and Northwest Aluminum Co., Ltd. have done a lot of work in the research and development and manufacturing of forging rings.
In 2007, Sinan aluminum overcame the technical difficulties of large casting, forging open billet, ring rolling and cold deformation, and developed a diameter 5m aluminum alloy forging ring. The original core forging technology filled the blank in China and successfully applied to the new generation of Long March 5 launch vehicle. In 2015, sinal developed the first large-scale aluminum alloy forging ring with diameter of 9m, which set a world record. In 2016, Sina successfully conquered several key core technologies such as rolling forming and heat treatment, developed a large-size aluminum alloy forging ring with diameter of 10m, and renewed the world record again, which solved major technical problems for the development of heavy-duty launch vehicle in China. In December, 2020, the forging ring won the first title of single champion product of manufacturing industry of Ministry of industry and information technology.
(Chongqing Xialu Xinda Aluminum Industry Co., Ltd. Publicity Department collates contributions)
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