Chengdu, Chengfei Group.

J-20 improvement project.

As the person in charge of this project, Yang Dacheng is discussing with a group of researchers from Dongtang Aerospace Group, and many people from Galaxy Aerospace Industry Group are also there.

The reason why there are people with aerospace systems here is mainly the result of the brains of the Chengfei Group, the rocket engine on the J-20.

"Chief Engineer Yang, we have already done it when you want to get the engine." Huang Qinxue of Dongtang Aerospace Industry Group handed a document to Yang Dacheng.

"Oh! It's great that we're all set now, all we owe is the east wind, have you brought your engine?" Yang Dacheng hurriedly asked while flipping through the documents.

Huang Qinxue pointed to the container not far away and said: "Bring it, there are four in total, but the power of the rocket engine is very powerful, can the J-20 fuselage withstand it?"

"We have been modified and strengthened, using a lot of carbon nanotube composites, and the empty weight of the aircraft is a little lighter than before, now it depends on your engine." Yang Dacheng said.

In fact, in the process of developing mass projectors and spacecraft, some technologies that can be applied in other fields will be born in the aerospace system.

As the closest aviation system to the space system, they are the first to be exposed to technological radiation, and the two have many technologies in common.

For example, the hydrogen and oxygen engines that can be reused on the spacecraft, such as the anti-radiation interference technology on the spacecraft, etc., these technologies can be applied to the aircraft.

After Yang Dacheng finished flipping through the documents, he turned around and instructed the assistant: "Let people pull the container inside and prepare to load the engine." ”

"Okay." The assistant hurriedly went to arrange this matter.

"I said, why is Chief Engineer Yang in such a hurry, it will take at least two or three days for the engine to be installed on the J-20, so you won't invite me to your canteen to eat?" Huang Qinxue pointed to his watch and teased.

Yang Dacheng saw that the time was already 12:24, and immediately reacted: "It's my negligence, and I will arrange dinner immediately." ”

"Then you're welcome." Huang Qinxue said with a smile.

"You don't dislike Cheng Fei's canteen, just coarse tea and light rice." Yang Dacheng said while leading the way.

Huang Qinxue suddenly remembered something as he walked, took out a list from his briefcase and handed it to Yang Dacheng: "But if you eat rice, you have to reimburse us for your four engines." ”

"Haha, definitely reimbursement." Yang Dacheng accepted the list with a smile.

Although both sides are state-owned enterprises, but the brothers settle the accounts, the total cost of the four engines is as high as 60 million Chinese yuan, of course, this is the first batch of manufacturing, including a large proportion of R & D costs, if it enters the stage of mass production, the cost of one may be about 200 ~ 3 million Chinese yuan.

The structure of the rocket engine is relatively simple and crude compared to the turbofan engine, and the various new technologies and new materials used in the current spacecraft make it even more simple and crude.

Yang Dacheng took Huang Qinxue and others to dinner, while the container was pulled into Chengfei's aircraft assembly workshop.

In the huge assembly workshop, many workers and researchers are busy, and a J-20 without an engine is quietly parked in the assembly workshop.

Since it is necessary to modify the hydrogen-oxygen engine, it is not only a matter of replacing the engine system, but also of the fuel system.

The fuel used in domestic hydrogen-oxygen engines is hydrogen solid fuel, and the fuel tank volume of the J-20 is 12.8 cubic meters, which can reserve up to 10 tons of aviation kerosene (the density of aviation kerosene is 0.78 tons per cubic meter).

12.8 cubic meters of hydrogen solid fuel (hydrogen solid fuel density is 0.47 tons per cubic meter), it is about 6 tons.

The calorific value of general aviation kerosene is 41840~42890 kJ/kg, wide fraction kerosene can reach 42890~43510 kJ/kg, and aviation gasoline is greater than 43090 kJ/kg.

The calorific value of hydrogen solid fuel is 129,000 kilojoules per kilogram, which is about three times that of aviation kerosene.

Theoretically, every kilogram of submetallic hydrogen can provide 3 times the power, as for why not use the same solid fuel mixture of hydrogen and oxygen as a spacecraft.

There are two reasons for this, the first is that airplanes mainly fly in the troposphere or stratosphere of the atmosphere, and there is oxygen in it; The second reason is that the use of oxy-hydrogen solid fuel will reduce the overall calorific value, because the calorific value of the oxy-hydrogen solid fuel mixture is 14,300 kJ/kg.

The main reason why the calorific value of hydrogen and oxygen solid mixed fuels has dropped so much is that the specific gravity of submetallic oxygen has increased, which has reduced the proportion of submetallic hydrogen as a fuel.

Theoretically, 10 tons of jet fuel can provide 430 million kilojoules, while 6 tons of hydrogen solid fuel can provide 774 million kilojoules.

In other words, after switching to a hydrogen-oxygen engine, the cruising range can be increased by 1.8 times while the engine power and fuel tank remain the same.

The maximum range of the J-20 is 5500 km, the radius range is 2000 km, and after switching to hydrogen-oxygen engines, the maximum range can be increased to 9900 km, and the radius range can be 3800 km.

Another advantage that cannot be ignored is that the weight has become lighter, and after 10 tons of aviation kerosene is turned into 6 tons of hydrogen solid fuel, there is an additional 4 tons of payload.

"Zhang Gong, the engine is coming." A staff member shouted to William Cheung, the engineer in charge of the assembly.

William Cheung immediately put down what he was doing: "Get the engine out." ”

"Okay."

After a while, two special hydrogen-oxygen engines (J-20 is twin-engine) were gently placed on a workbench by a crane.

"Add the weight of the two engines to the data and see how much the overall weight is?" William Cheung commanded.

The researcher hurriedly calculated, and soon the data was calculated.

"Zhang Gong, the overall weight of the empty aircraft is 15.7 tons."

Zhang Weiting raised his glasses and remembered this data, the original design of the J-20 empty aircraft was 19 tons, the maximum fuel load was 10 tons, and the maximum payload was 8 tons.

After the improvement, the J-20 empty aircraft is 15.7 tons, the maximum fuel load is 6 tons, and the maximum payload is 15.3 tons.

However, considering that the pilot's cockpit will be changed to an anti-load liquid cabin, the weight may need to increase by about 1.5 tons.

The final payload will be between 13.5~13.8 tons.

This improvement is simply a qualitative change, if you increase the fuel load, maybe you can increase the maximum range to more than 10,000 kilometers, and the radius range can reach 4000~5000 kilometers.

"Ready for installation right away." William Cheung commanded.

"Okay." Engineers and workers in the assembly shop hurriedly took action.

After Zhang Weiting ordered the engine installation work, he came to the side of the workshop, which displayed the anti-load support warehouse produced by Shanmei Anti-Load Support Warehouse Company, and the special anti-load maintenance warehouse for aircraft of Chengfei Group, which is a specially customized version.

The reason for the use of load-resistant life support chambers is mainly that the J-20 with hydrogen-oxygen engines is very fast, and it is very likely to break through 10 times the speed of sound.

In this case, the overload that the driver needs to bear will be very terrifying, and it may reach as much as twenty or thirty gigabytes in an instant.

And the anti-load technology of the spacecraft can just solve this problem.

The plane is more than 10 times the speed of sound, and even this speed is faster than most rockets, obviously this magic change of the Chengfei Group has made a qualitative change in the J-20.

If some systems are modified, they can even be used as aerospace aircraft, of course, due to the existence of mass projectors, the importance of aerospace aircraft is no longer great.

After all, no matter how awesome the aerospace plane is, it can't do the planetary railgun in the synchronous orbit.

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