Chapter 1125 Visit

Actually. Just as a technology. The role of the large aircraft project is also extraordinary.

Assuming that the test aircraft model is successful, localization will definitely bring about a substantial improvement in the manufacturing level of domestic enterprises. After the prototype flies along domestic routes for a week, the price of imported large aircraft parts is expected to drop by more than 30%.

If large aircraft prototypes can fly to the United States and back again, the price of imported large aircraft parts is estimated to drop by more than half, which means the import cost will be significantly reduced, which is a very low cost. From this point of view alone, there is also a research strategy with great economic benefits.

This speculation is not a fantasy, but a real fact, because at present, large aircraft are an absolute monopoly, and the price is not transparent. Even if it is transparent, the cost of foreign labor and resources is very high. If it is domestically produced, It is estimated that China can produce finished large aircraft at only one-third of the foreign cost. This will definitely have a huge impact on large aircraft manufacturers such as Boeing and Airbus.

Of course, the ones who were most affected were not foreigners, but a group of people from the Civil Aviation Administration of China. As well as the people in charge of the large aircraft procurement plan. Although these people have low positions and most of them are at the department level, the large amount of US dollars lost by the country because it does not have its own large aircraft basically comes from these people. It flowed from the hands.

As we all know, as long as there is a purchase, there will be a rebate, and the proportion of this rebate is quite large.

If there is anyone who is the most unhappy right now. These are the people.

The leaders who visited the China Aviation Manufacturing Group Corporation all had different ideas. The leaders from Lingxi Province were naturally quite excited. After all, the establishment of this large project base in Lingxi will bring considerable benefits to Lingxi Province. Influence, the future economic development of Lingxi will largely depend on the promotion of large aircraft projects.

The cadres and employees of the group company also felt a little emotional. Things that were so difficult to do when the state supported it are now so easy to do with a private boss, and the results are pretty good. They can't help but talk about the past. There are big problems with the system. Leader's personal will often overrides the interests of the country, which is very abnormal.

If there had been such an open environment as now, it is estimated that China's large aircraft manufacturing technology would have surpassed that of the Americans.

"It's not too late to catch up. I'm afraid we'll fall back if we don't advance." An old engineer who was responsible for leading everyone to visit said with emotion.

Everyone is convinced of this, just like domestic computer technology, which was also ahead of the curve. Haven't you been dumped in Java now? This is all the same.

Fan Heng, Fan Wubing and others also visited the model area and the three-dimensional animation design effect demonstration.

Large passenger aircraft need to cruise for a long time at an altitude of 9,000 to 10,000 meters with high sub-tones. Therefore, the wings generally adopt large aspect ratio swept wings with a sweep angle of about 35 degrees. In order to improve the performance of the wings in increasing lift during takeoff and landing, large passenger aircraft usually use full-span leading edge flaps or slats, and use double-slit or three-slit flaps on the trailing edge. The wings also use controllable spoilers. flow board.

This kind of spoiler has multiple functions. It can assist the ailerons in controlling the roll of the aircraft, and can also be used as a drag plate when the aircraft slows down. also. It can also be opened as a lift plate after the wheels touch the ground when the aircraft lands, so that the aircraft can land firmly on the runway and prevent the aircraft from rebounding.

Therefore, the auxiliary surface on the wing of a large passenger aircraft. It's not like a small plane with only four pieces (two flaps, two ailerons), but as many as fifty pieces. These fifty auxiliary surfaces must be solved in the design to solve the problems of function, structure, operation, vibration, etc. This is a special area of ​​large-scale integrated machine design.

However, these structural features have already been realized in the first large passenger aircraft developed in China, which saved a lot of time and energy.

The main characteristic of the large passenger aircraft fuselage is that when flying at high altitudes. Most of the fuselage is an internally pressurized pressure vessel. This determines that the cross-section of the fuselage is preferably circular, because containers with circular cross-sections are most beneficial to withstand internal pressure. Sometimes in order to increase the volume of the cabin, a double-circle figure-eight section is used. In this way, the upper and lower parts are composed of circles, and the middle is held by the floor beam, which is also ideal in terms of stress.

At the rear end of the cabin, the web of the frame is subject to a lot of outward pressure. If it were designed to be a strong flat plate to withstand the pressure, the structure would become very heavy. therefore. The rear end of the cabin is often designed to be spherical to take advantage of the situation, so that less material is used and it is easier to withstand pressure. This requires that the basic cross-section of the fuselage, whether circular or non-circular in design, should shrink into a full circle from the rear end of the cabin to facilitate the installation of the spherical frame.

This way, the doors and windows on the cabin. They all become openings on the pressure vessel.

Therefore, door and window frames should be designed so that the stress concentration caused by the opening is well dispersed. Large passenger aircraft have about a hundred portholes, and the window frames are basically designed according to the same form. The cabin door must have no threshold. This is so that if the aircraft overshoots the runway while taxiing, passengers must be able to smoothly pass through the door and use the emergency slide to leave the cabin in the shortest possible time.

On the other hand, the cabin door should be able to safely withstand the pressure in the cabin at high altitude, and it must not be ejected by the internal pressure like when opening a cork. Therefore, the locking mechanism of the cabin door should be designed to be safe and reliable. Moreover, there should be clear signs printed on the inside of the door to remind passengers not to tamper with the door handle during the flight. This is why.

Passenger seats in the cabin are fixed on slide rails mounted longitudinally on the floor beams. Therefore, when the aircraft is flying in the air, the seat position is very fixed and can withstand the impact of various landing situations to protect the personal safety of passengers.

But between each flight, if you want to adjust the position of the seat, such as adjusting the size of the first-class cabin, you only need to move the seat on the slide rail. This not only meets the needs of various flexible adjustments between flights, but also ensures safety during each flight.

This design has been adopted in the previously developed Y-10 aircraft in China. During the test flights, the seat layout in the cabin was adjusted and the installation of test instruments was arranged according to different needs between flights. This kind of adjustment is actually Very convenient.

In fact, the most critical technology is still the engine technology. This is the key issue for China to build large aircraft. Fortunately it has been resolved now. However, how effective it is and whether it can withstand the test of time over a long period of time still requires further testing.

There is an industry that supplies power units internationally. Whether it is China's small civil aircraft under development or aircraft from the American Boeing Company and European Airbus, manufacturers around the world are motivated to purchase them to match the aircraft. In fact, according to previous assumptions, when developing a new large passenger aircraft, the company will first purchase engines from global engine suppliers.

In the composition of the aviation industry, aircraft models are generally at the top of the pyramid. In today's open world, many people believe that the development of the domestic aviation industry needs to first occupy the commanding heights from top to bottom, and the development of aircraft models will be the first step. To drive the overall situation, as for the sub-systems that make up each part of the aircraft, they can be supplied in a fully matched manner, instead of laying the foundation stones of each layer of the pyramid from bottom to top, and then developing the aircraft model.

The aviation engine is a very complex, very precise, high-speed, high-stress, high-temperature piece of equipment. Technically, it can be said to be at the pinnacle of contemporary mechanical products.

In the past, when developing the Yunshi, two methods of engine supply were used in parallel. While developing domestic engines, they also purchased engines from foreign suppliers for use and compared the effects.

At present, the China Aviation Manufacturing Corporation has independently developed a domestically produced high-power aviation engine. It is the aviation engine with the highest thrust developed in China in recent years. This type of engine has passed strict ground testing and been installed on an aircraft for aerial test flight. The effect is still good, and it is currently being continuously tested and improved. Strive to improve it day by day, and derive various types of special aviation engines from it.

When the Y-10 was tested that year, the developers considered that if the aircraft and engine were newly developed, it would be difficult to determine the cause if some data deviated from normal during the test flight. Therefore, the Yun-10 was assembled with engines purchased from global engine suppliers in the initial flight test. As a result, the domestically produced aircraft and engines were tested separately and the results were good. The next step should have been to use Chinese aircraft equipped with domestic engines for the test flight, but unfortunately, the Yun-10 The project was permanently put on hold without any reason, and test flights were stopped.

During the visit, Fan Wubing also discovered a problem. In terms of the overall layout of the entire aircraft, the engines of some large Russian aircraft are very close to the fuselage. However, the current large aircraft project models we designed are different. What exactly is this? What are the different considerations?

The company's chief engineer explained to Fan Wubing. "Mr. Fan raised this question very well. The Soviet Union's first jet airliner was designed to install the engine on the wing root, which made the structural force transmission design of the engine installation and the arrangement of system pipelines very troublesome, and the maintenance of the engine was very difficult. The biggest The problem is that the noise of the engine jet will impact the fuselage, causing strong sound waves to annoy the passengers in the cabin. What's more serious is that the bulkhead of the pressure cabin will be fatigued and prone to accidents. In the early days of jet airliners, in addition to the Soviet Union, some European countries used them, but they were quickly abandoned.”

"Oh, that's it." Fan Wubing nodded and said that he had learned a lesson.