Some people question that core components such as engines are imported. Can C9 19 be regarded as a completely independent domestic product?
Of course. Although the core components of C9 19 depend on foreign suppliers, it is still a large passenger plane with independent intellectual property rights. The reason for this is that Comac China has formulated the overall design scheme in the early stage and has the right to decide the technical requirements of the components.
Fu Guohua, deputy chief designer of C9 19, said that just like a designer designing and decorating a house, although building materials and decorations are purchased from the market, matching them according to his ideas is the result of his design.
C9 19 is completely designed by our country. Chen Yingchun, the executive deputy chief designer of the project, said that the joint conceptual design is the most critical part of the project, including determining the layout of the wing, fuselage, tail, engine, landing gear and other components, the parameters of voyage and seat level, the engine magnitude, power supply and what kind of system to install.
Taking the passenger cabin as an example, Wu Shixing, a member of the National Expert Advisory Committee on Major Special Projects of Large Aircraft, introduced that C9 19 was designed to start with 150 seats in combination with the domestic market demand, and this scale of aircraft can be applied to more than 70 domestic airports. At the same time, it has the most spacious cabin in the current 150 single-aisle passenger aircraft, and its comfort is obviously better than all competing models. Its cabin noise can be controlled below 60 decibels, which is better than 80 decibels of similar models. Adopt a new air distribution system to make the air fresher, more uniform and with appropriate humidity. The design of the air outlet can speed up the air flow and prevent passengers from feeling uneven heat and cold. The somatosensory temperature target comes from the experimental data of China population.
Chen Yingchun said that the subsequent system joint definition design mainly described the aircraft to suppliers and told them the requirements of engines and systems. At the same time, China has carried out the preliminary design of aerodynamics, structural strength and system scheme, and gradually determined the aerodynamic shape and structure of the aircraft through simulation analysis, model making, wind tunnel test and structural strength test. "The aerodynamic shape was designed and tested by China himself," he said.
In order to reduce the air resistance, the shape of C9 19 has been improved on the mature passenger aircraft model, and every link such as nose, fuselage, wing tip and suspension has been slightly improved. Together, compared with competitive models such as Airbus and Boeing, the resistance is reduced by 5%.
Chen Yingchun introduced that when designing the wing, hundreds of top experts in domestic aircraft aerodynamics were gathered, and more than 500 ailerons were designed, from which the best one was selected to form the final design scheme. Tested in many countries in Europe and America, this wing makes the important indexes of C9 19 better than those of competing models, such as lift-drag ratio, cruise characteristics, stall characteristics, noise level and icing characteristics. Bai Junqiang, a professor of aircraft design engineering at Northwestern Polytechnical University who participated in airfoil design, said that this design can only be explored from scratch by oneself. After the success of C9 19, China people sat at the same discussion table with their foreign counterparts in aerodynamic shape design for the first time.
"The aircraft body, from design, calculation, testing to manufacturing, is made by China people themselves." Chen Yingchun said, "We also independently completed the system integration of the aircraft."
For system integration, some people don't understand: "Isn't it just assembly?"
Caroline Covey, vice president of Boeing Commercial Aircraft Group, once said: "If people can assemble the bought parts and make them fly, there will not be only two big aircraft manufacturers in the world."
Large aircraft is a complex system integration project. What needs need to be met when different systems are integrated? This control scheme is also in the hands of the C9 19 design team. "The intellectual property rights of China Commercial Aircraft are also reflected in the comprehensive control between systems." Wu Guanghui, the chief designer of C9 19, told the media recently that "there are millions of interfaces on C9 19 aircraft, which is related to the correlation of hydraulic and avionics systems. It is by no means a simple splicing. How to connect them depends on the design of the aircraft. "