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After all, Fan Heng was engaged in military production, so after looking at it for a while, he asked the chief engineer, "What are the requirements for materials when building large aircraft?" ”

When the chief engineer faced the Standing Committee and the executive vice premier, he still had a little psychological pressure, after all, such a big leader is really rare, but when he asked them about their profession, he naturally would not be stage frightened, "The metal and non-metallic materials used in large passenger aircraft have been basically supplied by domestic supporting when they were developed and transported in the past. In the development of large passenger aircraft today, the situation is somewhat different from that time, first of all, after the development of China's civil aircraft is in line with the world's advanced level, the materials need to pass the quality control verification according to airworthiness standards. -There are many kinds of materials used in aircraft, and it takes a process to complete the certification of all of them. In another different situation, it is not necessary to limit all the sources of materials to the country, but there are channels to purchase materials from abroad. In this way, the supply of materials for China's civil aircraft can be carried out in an orderly manner, on the one hand, to step up the improvement of the quality of domestic materials, in order to pass the certification work, on the other hand, some materials can be purchased from abroad.

The composite components used in large passenger aircraft are both materials and structures. The scope of the use of composite materials in civil aircraft has undergone a gradual increase process, so in China's large passenger aircraft, composite materials will be partially used to obtain experience in structural design and materials, so as to continuously expand its use in subsequent models to reduce the weight of the fuselage structure. ”

"Oh, that's right." Fan Heng nodded.

A female reporter from CCTV ran over and asked the chief engineer, "I heard that you told the college students about wearing padded jackets on airplanes, can you talk to our audience again?" ”

Fan Wuxian listened to the voice quite familiar, turned his head and looked, it was Lan Lan, a reporter who was very familiar with Ziqi in CCTV, and couldn't help but smile at her, I didn't expect people to concentrate on interviewing the chief engineer, and I didn't look at him at all, it's really a bit I will be sincere with Mingyue, but Mingyue feels like a ditch, I couldn't help but touch my nose, and laughed.

After listening to Lan Lan's question, the chief engineer felt that it was necessary to popularize science, so he smiled and said, "Oh, there is indeed such a thing." People need to wear padded jackets when they are cold, and the cruising altitude of large passenger planes is generally at an altitude of 9,000 to 10,000 meters. The average temperature in the troposphere of the atmosphere is below -50 degrees Celsius. Since the entire fuselage of a large passenger aircraft is basically a cabin, in terms of design, it is necessary to put on a padded jacket on the fuselage to keep the cabin warm. ”

Lan Lan asked, "So what is this padded jacket made of?" Where to put it? ”

The chief engineer replied, "The padded jacket of the fuselage of the aircraft is obviously not made of real cotton, because cotton is easy to absorb water and grow mold after a long time, and it is old and insect." Therefore, we choose glass wool made of inorganic glass silk as the raw material for warmth, as an inorganic substance, the property of this thing is very stable, both thermal insulation and shockproof, and the weight is very light. Therefore, the fuselage of the aircraft is made of a quilt stuffed with glass wool, which is laid in the space between the skin of the fuselage and the interior trim panels. ”

He added, "The entire cabin and cargo sections of the fuselage are wrapped in this glass wool quilt, which plays the role of sound insulation and warmth. The floor of the cabin, because the cargo hold is underneath, is also in the pressurized insulation area, so in a normal state, there is no need to be particularly insulated. However, in the part of the landing gear compartment, the cabin floor is ventilated to the atmosphere, and it is at a low temperature at high altitude, so the cabin floor at the landing gear compartment is covered with a resistance heating wire, which is powered in the air to keep warm, so as to prevent passengers from freezing their feet. ”

Lan Lan asked again, "Is the anti-noise design of large aircraft a gap in the field of design in China, and can China overcome this technical minefield?" ”

Regarding this question, the chief engineer was more solemn, "I can say very responsibly, no." China's first large-scale passenger aircraft developed in the 80s, the Yun-10, adopted the sound insulation and warmth method of glass wool quilt, so that the noise in the cabin of the Yun-10 in flight reached the international advanced aircraft level. Passengers experience low noise during the flight, and the crew can talk to each other at will. I have personally experienced this point when I flew the Yun-10 test flight in the past, and I feel the same as the feeling I felt when I flew around the earth on various foreign passenger planes. Today, we have made great strides in our materials technology and engine technology, so we are only going to get better and better, and the success of the big plane will become one of the most comfortable and safe aircraft in the world. ”

"Thank you very much for your cooperation, and finally I would like to ask a very confusing question, is there any special feature of the landing gear of large aircraft?" Lan Lan asked curiously while thanking the chief engineer.

"Well, that's a good question indeed. When the take-off and landing weight of a large passenger aircraft increases, the number of wheels needs to be increased to distribute the pressure on the runway of the aircraft, so that large aircraft do not need to require a particularly thick and solid runway to take off and land. The chief engineer explained, "On the small planes that people are familiar with, there are often only wheels installed under each landing gear strut. Passenger aircraft, with a slightly larger passenger capacity, increased the number of wheels by a factor of two, installing twin wheels under the main landing gear struts. When the total take-off weight of the aircraft reaches more than 100 tons, the number of wheels needs to be further doubled. Structurally, it is equipped with one frame under the landing gear strut, and four wheels on the frame. ”

For example, giant airliners such as Boeing 747 and Airbus A380 need to add wheels to disperse ground pressure, but also to add buffer struts to absorb the impact energy of the airframe when landing. The approach was to increase the number of struts of the main landing gear, not only on the lower surface of the wing - to the main landing gear, but also in the belly of the fuselage - to the landing gear struts, and under the buffer struts of the wing landing gear and belly landing gear, several wheels were installed with the frames.

Frame landing gear is also an important basic design type of large passenger aircraft, and the same domestic test flight in the 80s has successfully realized the frame landing gear design.

In the test flight, the Yun-10 has passed various tests of actual take-off and landing from Shanghai Airport with zero sea level to the world's highest altitude plateau airport, Tibet Gonggar Airport, and airports in northern and southern Xinjiang under different conditions.

In the subsequent international exchanges, China also undertook the design task of modifying the four-wheeled landing gear of foreign models, and the results were praised by foreign aircraft manufacturers. Therefore, the frame landing gear of large passenger aircraft is a technology that has been mastered and a position that has been conquered for the domestic aviation design industry.

"Just now you told the story of my country's modification of landing gear abroad. To which country? America? When, can you talk about it in detail? Lan Lan found that this topic should be more critical, so she asked another question.

Naturally, the chief engineer will not be stingy to say a few more words to cheer up the morale of the military, so he explained, "In the eighties of the last century, when China was assembling the MD-82 passenger plane of the United States, because the main landing frame of the aircraft was two-wheeled, the pressure on the ground exceeded the bearing capacity of some airport runways in China, so the Civil Aviation Administration officially required the American MD-82 passenger aircraft to be replaced with four-wheel landing gear, that is, to install a frame landing gear at the lower end of the pillar of the landing gear. The project is a cooperation between China and the United States, with China as the main project. After the Chinese side completed the design, it was praised by the US side. However, the modification project was not carried out on board the aircraft due to the withdrawal of the modification request by the Civil Aviation Administration. Despite this, China's design of the frame landing gear has been recognized by the relevant design departments in the United States. ”

After hearing the chief engineer's words, Fan Wuxian couldn't help but sneer, "Civil Aviation Administration, hey." ”

Due to the disgraceful role played by the Civil Aviation Administration in the process of disembarking the 10th project, Fan Wuxian now has a lot of resentment towards them, and Fan Wuxian also thinks that this kind of thing should be very reasonable, so he has no doubt that there is still a very serious bureaucracy and style in the current Civil Aviation Administration, after all, the annual large aircraft procurement case can be seen clearly there.

What's even more eye-catching is that the airport and ground construction, because there is no very strict regulatory mechanism, basically they say how much money they need to spend, and the oil and water in it are even more ridiculously big.

Fan Wuxian once thought of taking advantage of the situation to move the fat of the Civil Aviation Administration, but unfortunately now my father is still in a situation where his foothold is not stable, if he is re-elected this time, he has the ability to operate it.

The solution of the problem of the Civil Aviation Administration will be of great help to its own vigorous development of large aircraft manufacturing and civil aviation transportation in the future.

Of course, the most important thing is that Fan Wuxian has a deep grudge against them.

Especially when he visited the general blueprint of the design of the large aircraft project this time, Fan Wuxian found that so many key technologies were realized in the Yunshi project team, so the estimated design time was greatly shortened, and this alone can make Fan Wuxian save billions of R&D expenses and more than 10 billion yuan of trial production costs.

If Yun Shi hadn't been off the horse that year, would he still have to invest hundreds of billions of money to operate with Fan Wuzhi?

Thinking of this problem, Mr. Fan's heart is naturally quite uneasy, if he really finds this opportunity, he doesn't mind cleaning up these industry silverfish who will only be self-fertilizing.

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