An exclusive interview with C919 R&D team to see how domestic large aircraft grow up.
China Youth Daily Zhongqing Online Reporter Wang Yejie
If the weather is fine, China’s first domestic civil large passenger plane C919 will start its first blue sky trip on May 5, which marks a major leap in the field of civil aviation in China.
China’s civil aviation industry has been in a state of "buying imported goods" since the research and development of the domestic "Yun Shi" passenger plane stopped in the 1970s.
The turnover of civil aviation passengers in China has rapidly climbed from 23.048 billion person-kilometers in the early 1990s to 727.07 billion person-kilometers in 2015, with a compound annual growth rate of 15%.
C919 was developed in 2008, and now it is about to make its first flight. Every "growth process" of C919 has attracted much attention. Behind this big domestic bird, groups of young talents are also growing sturdily. From the "post-70s" in the early 20th century to the "post-80s" and "post-90s" now, behind the first flight of C919, there is a solid backing composed of young talents.
Data from Commercial Aircraft Corporation of China (hereinafter referred to as China Commercial Aircraft Corporation) show that more than 70% of the company’s young people are under the age of 35. When experts from related international fields visited Comac in China, they expressed such feelings: "The impressive thing about China Big Aircraft is not only the technology, but also the young people who are eager to fly behind it!"
The domestic large passenger plane C919 was tested at Shanghai Pudong Airport for high-skid lifting of the front wheels. Xinhua news agency
570 aircraft orders and 60% localization rate
Speaking of C919, I have to talk about the topic of "localization". Fans of the aviation industry may not forget the low standard of "the localization rate is more than 10%" at the beginning of the C919 project, and even this low requirement was considered by some senior aircraft enthusiasts to be difficult to achieve at that time; Today, the finished products delivered off the assembly line not only get 570 orders, but also have a localization rate of nearly 60%.
Some people question that the core engine and other components are all imported. Is the C919 a domestic product?
China Youth Daily Zhongqing Online reporter learned that the nose of C919 comes from Chengdu Aircraft Industry Group, the wing comes from Xi ‘an Aircraft Industry Group, the front and rear fuselage comes from Nanchang Hongdu Aviation Industry Group, and the front section of the rear fuselage comes from Shenyang Aircraft Industry Group.
As for the "kernel" of large aircraft, such as engine, communication and navigation equipment, C919 aircraft chose two paths — — First, foreign original factories and domestic joint ventures; Second, the original import, to a certain extent, to achieve partial domestic, and finally to achieve full domestic.
"Realizing all localization in the end" is the "technical market threshold" set by Comac China when purchasing original imported products. That is to say, once a product is purchased by Comac China, there is only one final "outlet" — — Gradually localized. This is the basic agreement between the product manufacturer and Comac China.
At the beginning of the C919 project, Li Keqiang, Premier of the State Council of the People’s Republic of China set a basic principle for domestic large aircraft — — Independent design, system integration, global procurement, and gradual domestic production.
Many people think that assembling some imported products is actually not too difficult and has no technical content. However, an interview with China Youth Daily and Zhongqing Online reporter found that for China people who have not been exposed to the research and development of civil large passenger aircraft for more than 30 years, the design, production and manufacturing process of C919 itself is full of innovations and challenges.
Take fiber material as an example, 15% of the fuselage of C919 is made of resin-grade carbon fiber material, which is the first time that this material has been widely used in large-scale civil passenger aircraft, and the utilization rate of this material in traditional large-scale passenger aircraft is only about 1%.
Others don’t use it, not because the material is not good, nor because the price is too expensive, but because this material requires too high installation accuracy, ordinary people can’t complete the accuracy required for "docking" with this material, so it is not used much.
Gao Yuan (first from the right)
Gao Yuan, deputy director of the aircraft assembly workshop of Shanghai Aircraft Manufacturing Co., Ltd. (hereinafter referred to as Shangfei Company), told China Youth Daily and Zhongqing Online reporter that the resin-grade carbon fiber material used in C919 is light in weight, and its weight can be 80% lighter than that of ordinary traditional materials under the premise of the same strength; Its fatigue life is also longer. Generally, the service life of metallic silver material is 20 years or 60,000 flight hours, but it can reach 30 years or 90,000 flight hours, and the structural life can be increased by 50%.
One problem is that when this material is used in aircraft manufacturing, the docking accuracy required is three or four orders of magnitude higher than that of rockets, and the method of realizing "accuracy" by traditional measuring tools is not applicable.
In the manufacturing process of C919, China people realized the automatic docking of large parts for the first time. Through laser positioning and tracking, the docking accuracy can be two orders of magnitude higher than in the past.
With the "shell", what about the core?
For example, if you cut a small hole in the outer shell of an airplane and fill it with a composite material, to what extent do you think it should be filled? The requirement of C919 is that it is invisible to the naked eye, and the "step difference" between the "patch" and the raw material is within 0.08 mm..
Wang Hui (center)
What is the concept of 0.08 mm? It is several orders of magnitude thinner than the thickness of mobile phone film. "Invisible to the naked eye, experienced masters can touch the difference with their hands." Wang Hui, deputy director of the manufacturing engineering department of Shanghai Aircraft Corporation, told the reporter that without a certain technical level, even if a Boeing 747 is disassembled and put in front of you, it is impossible for you to assemble it again.
Wang Hui said that the Manufacturing Engineering Department is equivalent to a translator, and it has to translate the drawings of the upstream aircraft design company into construction plans and technological processes that front-line workers can understand. Even if it is such a small and insignificant step, China people will go abroad to learn from it.
Before C919 started construction, COMAC cooperated with McDonnell Douglas to manufacture aircraft of McDonnell Douglas 82 and McDonnell Douglas 90. In this process, McDonnell Douglas provided the process flow, and COMAC was responsible for the production. To a certain extent, the cooperation with McDonnell Douglas makes the manufacturing engineering department of Shangfei Company grow gradually, and finally it can master the process independently.
Even so, some people will feel disdainful. Isn’t it just to build a shell? How much of the "core" is the result of China people?
Zhou Qiwei
Zhou Qiwei, 30, has the most say in this. All the cable-related departments on C919 are under his control and his team’s control. There are 24 of them, with an average age of around 30, but they are responsible for the most critical link in the normal operation of a plane — — 725 cables are arranged and laid, and 150,000 parts are installed and assembled.
These cables, like "nerve lines" and "blood vessels" in the human body, will lead to "organ" failure if they are not careful. The display may not be on, the throttle lever may be out of control, and the joystick may fail … … And all wiring, not a single drawing can solve the problem.
"Drawings are subjective designs, and everything is subject to the real thing." Zhou Qiwei told reporters that wiring often reflects the actual situation to the design team, and many design ideas cannot be realized in the actual wiring process. At this time, the wiring team also has to undertake some "design functions", propose modifications and feedback to the designer, and then wait for the designer to re-issue more realistic drawings. "Without talent, you can’t do this job."
The young and beautiful Gong Wenxiu is also responsible for the control of the "core" inside the aircraft. She is a member of the configuration management team of Shanghai Aircraft Design and Research Institute. Her job is to adjust the technical state of the whole machine to the best before the first flight. The navigation and communication system of aircraft can not be used directly after being bought and installed. It needs constant debugging and constant correction of system errors before it can operate normally.
Gong Wenxiu’s job is to "correct mistakes". Every inspection, she has to carry a thick stack of process specification materials in her hand and check them one by one. She and her team have to evaluate some system functions that cannot be realized for some reason. Why can’t they be realized? What is the impact on the first flight? Is it necessary to achieve it? Then give feedback.
Scale testing machine
What does "939, 949" look like after C919?
If the aforementioned "handsome men and beautiful women" are all preparing for the first flight of C919, then the following one is preparing for the future "C939 and C949".
His name is Zhang Chi, deputy head of the future product and technology research team of Beijing Civil Aircraft Technology Research Center (hereinafter referred to as Beiyan) of Comac China. He and his team are responsible for the "future model" of the C919. They gave themselves a rather dreamy name — — Dream studio, responsible for the "Lingque" project.
The "Lingque" project, to put it more popularly, is to design and develop a scaled-down large aircraft. This "Lingque" aircraft is more futuristic, unmanned and small, and the cost of an aircraft is less than 1% of that of the C919. But it carries the future of China’s big plane dream.
Lingque aircraft is a scaled verification model. It costs a lot to build a large plane and bears high risks in the field of innovative technology, but the smaller version of the "Lingque" can be more "dreamy" with low cost.
The latest "Lingque B" fuselage and wings are integrated, which is more economical and comfortable. Its tail has only two pieces, which is less resistant than the general three-piece tail plane.
This team, which is all composed of young people around the age of 30, is now doing research and development to solve the world-wide problems such as expensive air tickets and high fuel consumption of aircraft.
Franky Zhang
"Real innovation is not afraid of failure." Zhang Chi said that this team often received suggestions from peers in the past, "Is your plan feasible? Maybe not? "
However, Zhang Chi told reporters that in all kinds of discussions, Dream Studio has made nine scale testing machines since 2012, and there have also been cases in which small planes got out of control after take-off and ground dispatching was unsuccessful. "Without failure, it is not innovation, that is called imitation. We don’t do this. "
Zhang Chi said that youth is the capital of Dream Studio.
China Youth Daily Zhongqing Online reporter learned that Comac China has set up a total of 349 youth commandos, such as the young commandos for aircraft-level joint test of the C919 project of COMAC, and the young commandos for the assembly of the C919 large passenger aircraft system in the aircraft assembly workshop of COMAC, and named 60 youth civilization numbers, such as the composite material/structure research team of the North Research Center and the young technical team for field engineering of the test flight center.
Comac youth played a great vanguard and vital role in the flight test evidence collection of ARJ21 passenger plane, route demonstration operation, design and development, final assembly and manufacturing of C919 large passenger plane, and preparation for the first flight — — Ten youth innovation and entrepreneurship teams, with more than 230 members and an average age of less than 30, have undertaken 37 key technical problems of civil aircraft, including the control law of C919 large passenger aircraft.
Zhongqing Online Shanghai, May 4th