China's large aircraft localization rate is 60% to 100%. The follow-up models are already under development.

Speaking of the Chinese civilian self-made large passenger aircraft C919, I have to mention 3 percentages - 10%, 60% and 100%. This is the "localization rate" of large aircraft.
At the beginning of the C919 project, considering that the Chinese have not touched the "big aircraft" after the domestically-operated ten aircraft, China Commercial Aircraft Co., Ltd. conservatively estimates that the localization rate of the C919 can be greater than 10%; Later, this large Chinese aircraft, which was comparable to Boeing and Airbus, was able to achieve a localization rate of nearly 60% and received 570 orders.
The C919 will eventually achieve 100% localization. China Youth Daily·Zhongqing Online reporter learned that the C919 aircraft was selected for two parts that were temporarily unable to achieve domestic production during the manufacturing process. One is the foreign original factory and the domestic joint venture; the second is the original import, to a certain extent. Realize some domestic production, and finally achieve all domestic production.
“The ultimate realization of all localization” is the “threshold” set by China Commercial Aircraft when it purchases imported products. That is to say, once a certain product is purchased by COMAC, it will eventually be localized. This is the basic agreement between the product manufacturer and COMAC. "It’s hard to do this for the C919. It’s the first time."
If you compare an aircraft to a person, then the engine is the heart, the hydraulic system is the blood, and the control law is the soul. When the medium and short-range regional airliner ARJ21-700 developed by COMAC was conducting various test flight verifications, the design of the domestic large aircraft C919 also began to race against time.
“The control law is actually an algorithm.” Zheng Xiaohui, deputy director of the Operational Characteristics and Control Law Department of Shanghai Aircraft Design and Research Institute, introduced the control law of the fly-by-wire flight control system according to professional explanation. The control law indicates the relationship between the pilot's maneuver and the aircraft's motion response, and the feedback control algorithm is used to obtain the aircraft's desired aircraft handling characteristics.
Taking the automatic parking technology as an example, the current automatic parking technology can make the operator press the button to set the target, and the car stops at the designated position. In this process, the algorithm plays a crucial role. “It seems that the car has poured in itself, but in fact the sensor on the car measures the distance, angle and other factors. Through the calculation of the data, the wheel is controlled to complete.”
The algorithm of the flight control law also plays the same role. The more complex the control law algorithm is, the lighter the pilot's burden is, and the easier it is to control the aircraft. “By designing the algorithm, the aircraft is more intelligent and reduces the possibility of people making mistakes.”
In 2012, COMAC established a research team based on the design characteristics of the Shanghai Aircraft Design and Research Institute and the design of the control room, and designed the fly-by-wire flight control law for the C919. Four years later, this team, which was mainly composed of the 80s, initially completed the design.
COMAC has developed its own algorithm for the flight control law of the C919. The ARJ21-700 regional aircraft uses a relatively simple open-loop control law. Many operations require the pilot to do it manually. The C919 uses a much more complex closed-loop control law, and the pilot's manual operation is much less.
Honeywell is a supplier of the C919 flight control system. Subject to US law, it cannot provide the C919 project with the flight control law algorithm, which can only be independently developed by COMAC. During the development process, Honeywell is only responsible for the implementation of the functions and solutions designed by COMAC. For questions about whether the program is suitable, Honeywell only answers “yes” or “no”, and the fault is located and excluded by COMAC.
"It is difficult for the C919 to do the control law. This is the first time." Zheng Xiaohui said that compared with foreign countries, China's experience in flight control law algorithms is seriously insufficient. Once the first design is completed, the design of subsequent models will be much easier. For example, the Airbus A320 is also the first time to telex, to 330, 340, as long as the adjustment based on 320, will soon be able to make new algorithms.
COMAC has set up a special shuttle bus for the algorithm research team, which is going to the subway station every night at 10 o'clock. There are several folding beds in the office, and if you get off work late, the young people will sleep directly in the office. This office has an unwritten "regulation". Everyone must add at least 3 shifts from Monday to Friday, 1 shift on Saturday, and 21:00 from Monday to Friday. Everyone treats everyone equally, insisting at least Two years.
Each time, the team designed the algorithm, and also formed the system technical specifications, all translated into English and sent to the supplier, and then the software code was written by the supplier. Team member Zhao Jinghui introduced that they have more than 4,100 English requirements for the control law designed for the C919, and more than 200 English teleconferences were held before and after the supplier.

"crazy" material that can't be bought
For the first time, advanced materials have been applied on a large scale in the C919.
In its "skin", the amount of third-generation aluminum-lithium alloy materials and advanced composite materials reached 8.8% and 12%, respectively, while the previous application on the ARJ passenger aircraft was only 1%. ARJ's new materials are used for non-load-bearing structures, while the C919 is used in the rear section of the fuselage and in the load-bearing parts such as the flat tail. For the "competitors" of the Boeing 737 and Airbus A320 models, the use of advanced composite materials on the C919 is also more.
Therefore, the C919 is considered to be “a landmark in the field of materials in China”. According to public information, the new material makes the larger C919 lose more than 7%.
Yuan Yuhui, deputy director of the Standard Materials Design and Research Department of Shanghai Aircraft Design and Research Institute of COMAC, told reporters that the composite materials used on aircraft mainly refer to carbon fiber reinforced resin-based composite materials, which have the characteristics of light weight and corrosion resistance, which can not only reduce the aircraft's Self-weight, increase passenger capacity, and reduce the cost of post-maintenance.
In the words of Deng Yunlai, a material science expert and professor at the School of Materials Science at Central South University, the “skin” of the aircraft is the symbol of a generation of aircraft, “a generation of aircraft, a generation of materials”. The lighter the material and the better the durability, the better the performance of the aircraft.
China's material science is still in a relatively weak position in the world. The 10 civil aircraft developed more than 30 years ago is the “all-metal texture”. The composite materials currently used by the C919 are all from foreign suppliers, but in the absence of basic material standards, even if you buy from a foreigner, it is extremely difficult.
What Yuan Yuhui has to do is to formulate the selection criteria for each part of the C919 according to the performance requirements of the aircraft. She told reporters that every type of aircraft produced by every aircraft manufacturer in the world has a set of exclusive material standards. These material standards, like Coca-Cola's mysterious formula, have independent intellectual property rights - they can't be bought.
It took Yuan Yuhui and the team four years to determine the standard text and content of the C919 material, but the fiber amount, tensile length, resin content, physical properties, chemical properties, mechanical properties, etc. of each material in each part. Data, but also to re-experiment, and then use statistical algorithms to get reasonable values. This reasonable value must be guaranteed to meet the design requirements of the C919, but also the possibility of production, and ultimately endorsed by the airworthiness authority.
Over the years, the Standard Materials team has been designing and manufacturing a front-line survey almost every day. The actual engineer will tell them which kind of material is needed, softer, stronger, and lighter. The “a little bit, some” in the engineer’s mouth, when it comes to the materialist, must be quantified as specific parameters. .
Each of these parameters is obtained by the materialist through a tedious and tedious way of laboratory comparison, practical measurement, and the like.
It is worth mentioning that with rich experience in the field of materials, Yuan Yuhui team has been guiding the auxiliary materials production enterprises of AVIC and a private enterprise in Jiangsu to carry out material optimization and innovation. “In the past, we only told them what to do and not to do. Even if it comes out; now we can help them analyze, where the problem may be, and how it can be improved."

C929, C939 Dreamliner is already under development
The Chinese big plane dream will never stop at the C919. China Youth Daily·China Youth Online Reporter noted that dream models such as C929 and C939 are also being developed intensively.
Zhang Chi is the deputy head of the future product and technology research team of China Commercial Aircraft Beijing Civil Aircraft Technology Research Center. He and his team are responsible for the C919's "future models." They gave themselves a special name "Dream Studio", responsible for the "Flesic Birds" project.
The "Lingque" project, which is more popular, is a large aircraft designed to develop a reduced version. This kind of "spirit" aircraft is more futuristic, unmanned, and active. The cost of such an aircraft is less than one percent of the C919, but it carries the future of China's big airplane dream.
The "Lingque" aircraft is a reduction ratio verification model. Zhang is proud to show reporters the latest "Fei B" aircraft, its fuselage and wing integrated into one, more economical and more comfortable, its tail has only two pieces, less resistance than the average three tail aircraft .
This team of young people around the age of 30 is working on a worldwide solution to the problem of expensive airline tickets and high fuel consumption.
The "recommendation" of the peers most often received by the relaxation team is: You may not be able to do this program?
In various discussions, Dream Studio has done 9 reduction ratio test machines since 2012, and there have been cases where the small planes lost control after ground takeoff and the ground dispatch was unsuccessful. "Without failure, it is not innovation, it is called imitation. We don't do that."
China Youth Daily·Zhongqing Online reporter learned that in the ARJ21 passenger aircraft flight testimony, route demonstration operation, and C919 large passenger aircraft design and development, final assembly manufacturing, and first flight preparation work, Shangfei Youth played a great role - 10 youths The innovation and entrepreneurship team, with more than 230 members, with an average age of less than 30 years old, has undertaken the key tasks of 37 civil aircraft key technologies such as the C919 large passenger aircraft control law.

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