Dongmei led the two girls, Yu Duxue and Liu Muyun, into the living room to meet Liang Yunying and Zhu Jingyuan.

Both girls lowered their heads, but the tall Liu Muyun was obviously lower.

However, Dongmei was beside her, carefully reminding the two to look up, so that Zhu Jingyuan could see clearly, and the two raised their heads.

Zhu Jingyuan looked at the scene, more real than through the glass, and still nodded with satisfaction:

"Okay, that's good, let's pick a day."

The formal meeting soon ended, and the officials of the royal palace were going to go to the formal ceremony.

In the late Ming Dynasty in history, legal concubines already had a relatively standardized marriage process, but it was simpler than marrying a wife.

At the very least, a marriage certificate must be made, and the ceremony can be regarded as a marriage match.

Only those who are nominally concubines, but are actually slaves, will be very casual.

Pay the money to buy the deed and put it in the backyard for use, without any clear etiquette process.

Because Emperor Shizu forbade the Ming people to be slaves, this situation would no longer appear for the Ming women.

At the same time, after the Renwu Dynasty, the first time the prince and grandson before the age of twenty took a concubine, the date of choice was not mainly based on whether it was auspicious, but on the concubine's menstrual cycle.

According to the experience left by Emperor Shizu, coupled with the long-term records and verification of the Tai Hospital, the doctors of Daming have now basically determined the rules of women's conception period (ovulation period) and infertility period (safe period).

Before the age of twenty, the prince and grandson only have two chances a month.

The most important thing to do for the first concubinage is to confirm fertility.

Therefore, the concubinage ceremony will be placed during the concubine's conception period, and the union will only be in the fertile period for at least one year thereafter.

If he insists on doing this with his two concubines for a year, and this prince and grandson still have nothing to do, then he will basically be abolished.

Although I can take two more concubines to continue to work hard, even if I give birth to a child in the future, I will have no chance to succeed to the throne.

Dongmei, the big girl, left with Zhu Jingyuan's two preparatory concubine rooms and went to the small room to inquire about the situation privately.

Liu Muyun's conception period is approaching, and it is scheduled for seven days later, and Yu Duxue has just passed, and it is scheduled for twenty-three days later.

Zhu Jingyuan's concubine matter is an absolute matter in the Great Food Country.

Imperial Concubine Liang Yunying sat in charge and personally commanded, Dongmei and Chunxiang followed and urged, and the palace quickly got busy.

Zhu Jingyuan himself doesn't have to worry about these things, and he really doesn't have to worry about the backyard after his mother comes.

The next morning, Zhu Jingyuan got up to eat, train daily, bathe and change clothes, and then went to the martial arts arena in the backyard of the palace.

The fleet has been on the third day, and it is finally time to meet the people Zhu Jingyuan is most interested in - the craftsmen of Daming Airlines.

Zheng Fuguang, a great worker, with a group of craftsmen who were willing to come to Da Shiguo, waited for Zhu Jingyuan in the martial arts arena, of course, not to practice martial arts.

Instead, he wanted to show Zhu Jingyuan the results of last year or so.

There were a lot of wooden racks and boxes around them, and next to them were dismantled machines.

There are also two planes, a car, a motorcycle.

When Zheng Fuguang saw Zhu Jingyuan coming, he immediately led the team to salute together:

"See Your Highness."

Zhu Jingyuan walked over quickly, looked at the machines all over the ground, and said with a very happy smile:

"No need to be polite, you have worked hard, this way, this year.

"We don't have anything in the big food country, so we can only pay you more."

The scene erupted in laughter.

The craftsmen have all listened to Zheng Fuguang's introduction to Zhu Jingyuan, and his personality is particularly hearty and kind, and the key is that he is also very generous.

When I saw this today, I first said that I would pay the money, and the craftsmen were very happy.

There is no one who does not like such a boss.

After saying hello, Zheng Fuguang introduced the surrounding machinery to Zhu Jingyuan.

Zheng Fuguang's original major is actually mechanical, and drilling is actually a part-time study.

Although these machines were not designed by Zheng Fuguang, they were fully understood before they came.

Zhu Jingyuan came to the motorcycle first and looked down at the wheels slightly.

The engine of this motorcycle is mounted on wheels.

Centered on the axle of the wheel, five cylinders surround it, and look like a five-pointed star from the side.

This is a type of radial engine - the rotary engine.

Zhu Jingyuan asked the craftsman to put the wheels up and tried to start the engine on the spot.

The engine on the axle starts to spin, and the cylinders rotate with it, and the wheels follow suit.

The spindle is fixed, and the cylinder rotates like a windmill, so it is called a rotary engine.

The rotating cylinder can store energy and function as a flywheel, omitting a dedicated flywheel.

The cylinder itself rotates at high speed, which is equivalent to its own air cooling, and there is no need for a special cooling structure.

These features make the structure of the engine itself very simple.

Its application is also very simple, it can be installed directly on the wheel, without the need for complex transmission structure.

The engine drives the wheels directly and drags the body forward.

This kind of engine appeared very early, before Zhu Jingyuan regained his memory.

It seems to be full of advantages, so it was very popular in history before and after World War I.

But it also has two huge drawbacks – sealing and weight.

After Zhu Jingyuan turned off the engine, Zheng Fuguang introduced next to him:

"The power of this rotary engine is 32 horsepower, which is the maximum speed of a two-wheeler...... No actual results have been obtained.

"No one dares to drive to its limit, and the maximum speed measured is 160 kilometers per hour.

"The Ministry of Industry and the Royal Machinery Company have produced the same engine with about 160 horsepower.

"The engine is simple and easy to install.

"But the oil circuit is difficult to seal and pressurize, and the exhaust is not easy to collect.

"Because these structures are active, this severely limits its power build-up.

"At the same time, the higher the number of cylinders, the greater the torque of inertia during rotation.

"It's fine to install it in a car, but if it is placed on an airplane, the huge inertial torque will seriously affect the handling performance of the aircraft.

"When you start the engine on the ground, it keeps the plane sliding sideways.

"At present, institutions including our Daming Airlines, Daming Flying Machinery, and the Ministry of Industry have basically given up on continuing to develop it.

"The research direction of the new engine has shifted to the new star engine you designed."

Zhu Jingyuan nodded lightly:

"This is an inherent problem with the cylinder structure, and there is no way to completely eradicate it.

"It's the pursuit of extreme simplicity design, which leads to the corresponding unsolvable defects.

"So my new radial engine is a relatively compromise design."

Zhu Jingyuan said something and came to the front of a plane.

The structure of this aircraft is very different from the previous ones, it has only one wing, it is a monoplane.

The aircraft was built entirely of steel and aluminum.

The overall shape is also made according to Zhu Jingyuan's design.

It is almost the same as the German F-190D and the British Sea Fury fighter at the end of World War II.

Zhu Jingyuan took a look at the number of cylinders in the engine in front of the plane:

"This aircraft uses an air-cooled nine-cylinder engine, how much power has it achieved? What about speed and range?"

Zheng Fuguang immediately said with emotion:

"This one is rated at 400 hp and a 600 hp one is under development.

"The cruising speed is 300 kilometers per hour, the maximum range is 600 kilometers, and the combat radius can be 200 kilometers.

"According to the Governor's Office

The law already has a strong practical significance, and military models have begun to be mass-produced.

"The most important thing is the engine, without which none of this can be achieved.

"Your Highness designed this kind of engine, which is extremely ingenious and extremely expansible when mounted on an airplane.

"In the future, the increase in engine power is a pure process upgrade and the number of cylinders.

"In the future, it's only a matter of time before the power is increased to 800 hp, or even 1,000 hp.

"At that time, the speed of the aircraft may increase to 400 or even 500 kilometers per hour."

The new star engine designed by Zhu Jingyuan was the main engine of the carrier-based aircraft of the World War II era.

Compared to the previous World War I engines, its shape looks little changed, and it still has a ring around the cylinder rings.

The biggest change is that the cylinder itself no longer rotates, and the middle spindle rotates.

Its disadvantages are also very obvious, and it is necessary to design a special cooling method.

But the propeller is in front of the aircraft engine, and the propeller can cool the engine by blowing the air.

Therefore, if it is used in an airplane, the convenience is not much different from that of a rotary cylinder engine, and it also comes with air cooling.

The advantages are also very obvious, the oil supply, pressurization, and exhaust structures are all fixed, which is convenient for production and maintenance.

The engine spindle is directly connected to the propeller, which does not require any deceleration and transmission structure.

The most important advantage is that the monolithically fixed star engine can be made larger, and the number of cylinders can be larger.

Cylinders can be five, seven, nine, and can even become two rows of eighteen cylinders, or even four rows of twenty-eight.

The follow-up technology is mature, and a turbocharged structure can be added.

Zhu Jingyuan thought about the engine he had heard of in his previous life, and nodded with a smile:

"It's still conservative, 1,000 horsepower is just the beginning, 2,000 horsepower is mature, and the limit should be more than 3,000 horsepower."

Zheng Fuguang and a group of craftsmen were originally happy, and even quite proud.

In the past year, the engine power has increased from more than 60 horsepower to 400 horsepower, an increase of six times.

The key is the performance of the aircraft, which has also been turned upside down.

Zhu Jingyuan now reminded them that on the basis of 400 horsepower, it would be increased by at least five or even eight times.

This is a bit of a shock in the end.

Zheng Fuguang asked excitedly and stunned:

"Your Highness...... Two thousand to three thousand horsepower? Can you really do it that high?"

Zhu Jingyuan smiled and nodded:

"Yes, but it has limits, similar to the limits of rotary engines.

"The weight is getting heavier, the mechanical structure is complex, and maintenance is becoming more and more difficult.

"At that point, there will be new types of engines to replace them.

"Another type of engine with a simpler structure and higher power density......

That is, jet engines.