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Actually, just as a technology. The role of large aircraft projects is also very powerful.

Assuming the success of the test aircraft type, localization will definitely bring a substantial increase in the manufacturing level of domestic enterprises, and the prototype will fly along the domestic route for a week, and the price of imported large aircraft parts is estimated to fall by more than 30%.

If the prototype of the large aircraft can fly to the Americas and fly back, it is estimated that the price of imported large aircraft parts will fall by more than half, that is, it will greatly reduce the cost of imports, which is a very low cost.

This speculation is not a dream, but a real fact, because at present, the large aircraft is an absolute monopoly, the price is not transparent, even if it is transparent, the cost of foreign labor and resources is very high, if it is localized, it is estimated that only one-third of the foreign cost can come up with a large aircraft finished product, which will definitely make Boeing and Airbus and other large aircraft manufacturers suffer a huge impact.

Of course, it is not the foreigners who will be hit the hardest, but a group of people from the Civil Aviation Administration of China and those in charge of the large aircraft procurement plan. Although the positions of these people are not high, and most of them are cadres at the department and bureau level, the large amount of US dollars lost by the state because it does not have its own large planes has basically flowed out of the hands of these people.

As we all know, as long as there is procurement, there must be rebates, and the proportion of this rebate is quite large.

If there are the most unhappy people right now, it's these people.

After all, the landing of this large project base in Lingxi will bring considerable influence to Lingxi Province, and the economic development of Lingxi in the future will largely depend on the pull of the large aircraft project.

The cadres and workers of the group company also felt some emotion, what was so difficult to do when the state supported it in the past, but now it has been done so easily by a private boss, and the effect is not bad, I cannot help but say that there were big problems in the past system, and the personal will of the leaders often overrides the interests of the state, which is very abnormal.

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

"It's not too late to catch up, I'm afraid that if you don't advance, you will retreat—" said an old engineer who was responsible for leading the tour with some emotion.

Everyone thinks deeply about this, just like the domestic computer technology, which was also ahead of the curve at the beginning. Haven't you been dumped in Java yet? It's all the same.

Fan Heng and Fan Wuzhi also visited the model area and the demonstration of the 3D animation design effect.

Large passenger aircraft need to cruise at an altitude of 9,000 to 10,000 meters at high subsonic speed for a long time, so the wing generally adopts a sweep wing with a large aspect ratio, and the sweep angle is about 35 degrees. In order to improve the efficiency of the wings during take-off and landing, large airliners often use full-span leading edge flaps or slats, while double- or triple-slit flaps are used on the trailing edge, and the wings also use steerable spoilers.

This spoiler has a variety of functions, such as assisting the aileron in maneuvering the aircraft roll, and can also be used as a drag plate when the aircraft is slowing down. In addition, when the aircraft lands, it can also be opened as a lifting plate after the wheels touch the ground, so that the aircraft can firmly land on the runway and prevent the aircraft from rebounding.

Therefore, the auxiliary surfaces on the wing of a large airliner do not have only four (two flaps and two ailerons) like small airliners, but as many as fifty. These 50 auxiliary surfaces have to be solved in design - solving problems such as function, construction, handling, and vibration, which is a special area of large aircraft design.

However, these structural characteristics have been realized on the first large passenger aircraft developed in China. At this time, a lot of time and effort is saved.

The main feature of the fuselage of a large airliner is that when flying at high altitude, the vast majority of the fuselage is an internally pressurized pressure vessel. This dictates that the profile of the fuselage should be preferably round, since the container with a circular profile is most advantageous to withstand internal pressure. Sometimes in order to increase the volume of the cabin, a figure-8 profile with a double circle configuration is adopted, so that the upper and lower parts are composed of circles, and the middle is pulled by a beam of the floor, which is also ideal in terms of stress.

At the rear end of the cabin, the web of the frame is subjected to a lot of outward pressure, and if it is designed to be a sturdy flat plate that is hard to withstand the pressure, the structure will become heavy. As a result, the rear end of the cabin is often spherical in shape, which uses less material and is easier to withstand pressure. This requires that the basic section of the fuselage, whether it is a circular or non-circular design, should be reduced to a full circle to the rear end of the cabin to facilitate the installation of spherical frames.

In this way, the doors and windows in the cabin become openings in the pressure vessel.

Therefore, the door frame and window frame should be designed so that the stress concentration caused by the opening is well dispersed. Large passenger aircraft have about 100 portholes, and the basic and unified window frames should be designed according to the reinforced form. The door of the cabin must be threshold-free in the type, which is so that if the plane rushes out of the runway in the ground taxi, passengers must be able to smoothly pass through the door and leave the cabin in the shortest possible time with the emergency slide.

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

Passenger seat in the cabin. It is fixed on the slide rails that are longitudinally erected on the floor beam. Therefore, when the aircraft is flying in the air, the position of the seat is very fixed, which can withstand the impact of various landing situations and protect the personal safety of passengers.

However, between each flight, if you want to adjust the position of the seat, such as adjusting the size of the cabin, you can simply move the seat on the rails. This not only meets the needs of various flexible adjustments between flights, but also ensures the safety of each flight.

This design was adopted in the previous Yun-10 aircraft developed in China, and in the test flight, according to different needs, the seat arrangement in the cabin was adjusted between flights, and the installation of test instruments was arranged, and so on, and it was actually very convenient to make this adjustment.

In fact, the most critical technology is still engine technology, which is the key issue for China's large aircraft. Fortunately, it has now been solved, but further experiments are still needed on how effective it will be and whether it will stand the test of time over a long period of time.

At present, whether it is China's civil small aircraft under development, the Boeing Company of the United States, or the aircraft of Airbus of Europe, they all purchase engines from manufacturers around the world to match the aircraft. In fact, according to the previous assumption, when developing a new large passenger aircraft in China, it will first purchase engines from the world's engine suppliers.

In the composition of the aviation industry, aircraft models are generally at the top of the pyramid, and in today's open world, many people think. The development of the domestic aviation industry needs to occupy the commanding heights from top to bottom, and the development of aircraft models to drive the overall situation, as for the sub-systems that make up the various parts of the aircraft, they can be supplied by means of global support, rather than laying the cornerstones of the pyramid from the bottom up, and then developing aircraft models.

Aero engine is a very complex, very precise, high speed, high stress, high temperature equipment, in technology, it can be said to be in the best position of contemporary mechanical products.

In the past, when the Yun-10 was developed, two engine supply methods were paralleled at the same time. At the same time as developing domestic engines, we also purchase engines from foreign suppliers to use them, and compare the results.

At present, the domestic high-power aero engine developed by China Aviation Manufacturing Corporation is the largest thrust aero engine developed in China in recent years, the engine has undergone strict ground test runs, and installed on the aircraft for air test flight, the effect is still good, is currently constantly testing and improving, striving for perfection, and from it derived various types of special aero engines.

During the test flight of Yun-10 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 initial test flight of the Yun-10 was equipped with engines purchased from the world's engine suppliers, and the results of the test flights of the domestically produced aircraft and engines were good, and the next step should have been to use the Chinese aircraft to install the domestic engine for the test flight, but unfortunately the Yun-10 project was permanently shelved for no reason, and the test flight was stopped.

During the visit, Fan Wuxian also found a problem, that is, in the overall layout of the whole aircraft, the engines of some large Russian aircraft are very close to the fuselage, but at present, the large aircraft project model we designed ourselves is not very different, what are the different considerations?

The chief engineer of the company explained to Fan Wuxi, "Mr. Fan has raised this question very well, the Soviet Union's first jetliner Tu-104 is to install the engine in the wing root, which makes the structural force transmission design of the engine and the arrangement of system pipelines very troublesome, and it is very difficult to maintain the engine." The biggest problem is that the noise from the engine jets can impact the fuselage, causing passengers in the cabin to be annoyed by strong sounds. What's more serious is that the bulkhead of the pressure cabin causes sonic fatigue and is prone to accidents. Therefore, this wing root engine layout, in the early days of jetliners, in addition to the Soviet Union, was adopted by some European countries, but it was quickly abandoned. ”

"Oh, I see-" Fan nodded and said straightforwardly.

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