Late Yuan Dynasty: I am the true emperor

Chapter 440: Become the King before Going to War (asking for monthly tickets)

After agreeing to Lu Jin to develop steam engines and chemical technology, Tao Guangyi became confused again.

"But Your Highness asked me to go and see the huge ship at the dock. Mr. Wang also said that all 96 guns on that ship would be built under my supervision. Shouldn't we build the guns first?"

Lu Jin immediately explained, "You mean the ship? Although it was built in the shape of a battleship, we don't need it to fight now. Just install a few cannons on it. Mr. Huanzhang has other tasks.

"When you came, you saw that the ship was almost finished. It will be finished in three months, by the end of October. Then we will call up the sailors for training for half a year and prepare to set sail in May next year. Mr. Huanzhang will go to sea with the ship. Even if you start making cannons now, you may not be in time.

"Moreover, the navy's guns are different from the army's guns. They need to be redesigned and re-molded. Don't you know that the range is related to the length of the gun barrel?"

Tao Guangyi nodded immediately.

Lu Jin then asked, "Then do you know the difference between the navy's guns and the army's guns?"

"Longer?"

"That's right. The army has to consider the issue of artillery accompanying the march, so it can't just pursue range and power. Under the premise of meeting the power and range, the lighter the better. This way it will be easier for you to cross ditches and bumps, or build a pontoon bridge to cross the river.

"But the navy is different. The navy's guns are all installed on ships and do not need to be moved or marched. Therefore, the power and range should be given priority, and the weight does not need to be restricted too much. Therefore, the gun barrels can be made longer and heavier, and larger caliber shells can be used."

Lu Jin held a fountain pen in his hand as if it were a cannon and explained, "A cannon is an iron tube. The gas released by the burning gunpowder pushes the shell forward. The larger the charge and the longer the barrel, the farther it can hit. But you can't just keep increasing the charge.

“For example, a 8-jin cannon can fire a solid iron bullet weighing 8 jin. If the inner wall of the barrel is not smooth enough and the bullet is not polished round enough, it will lose its momentum and may need 6 jin of gunpowder to fire it three miles away. But if you load so much gunpowder, the barrel wall cannot be too thin, otherwise it will easily explode. However, if the barrel wall is thick, the weight of the gun body will not be able to hold it down. A cannon like this may weigh more than 2,000 jin and require eight horses to pull it.

“On the contrary, as long as the inner wall of your gun barrel and the size of the shell are accurate enough, and they are polished smooth and round enough, the airtightness will be very high, and you only need to use less powder to achieve the same range. With less powder, the power of gunpowder becomes smaller, and the gun barrel can be made thinner and lighter, and it will not explode. In this way, it may only weigh 1,400 to 1,500 kilograms, and only six horses, or even four horses, can be pulled.

"With our current processing technology, the airtightness is relatively high, so the amount of gunpowder is generally one-third of the weight of the shell. For example, to fire a shell weighing eight kilograms, we use two kilograms, six ounces and six cents of gunpowder.

"There is no need for soldiers to weigh the gunpowder on the battlefield. It can be weighed directly at the gunpowder factory and sewn into a cylindrical cloth bag. This is called a standard gunpowder bag. In the artillery manual, it can be simplified to No. 1 charge. The officer only needs to order the number of charge, and the soldiers can take it and load it directly, which increases the firing speed.

"The Yuan army loaded gunpowder on the battlefield. For every round they fired with their bowl-mouthed guns, I could have fired five rounds."

"So that's how it is. Thank you for your teachings, Your Highness." Tao Guangyi suddenly realized, and thought to himself that it was worth it to become his disciple, as he could learn such confidential things right after becoming its disciple.

Lu Jin continued, "So the barrel thickness and charge are not determined blindly, but calculated, and the same goes for the barrel length.

"The cannonball is propelled by gunpowder gas. The longer the acceleration distance of the gunpowder pushing the cannonball forward, the greater the initial velocity of the cannonball when it flies out of the muzzle, and the longer the range. It's like when you throw a stone, the harder you throw, the farther the stone will go.

"But the longer the barrel, the better, because the energy density of black powder is limited. Do you know that the volume of smoke released after burning black powder is many times that of the gunpowder itself?"

"I don't know, even this has its own requirements?" Tao Guangyi had no idea about this. It was the first time he heard that when designing a cannon, even the gunpowder gas multiples had to be calculated.

"Of course. Otherwise, how would you know how long the barrel should be? I won't let you do the experiment yourself. I'll tell you directly that the expansion volume of black powder gas is about 2000 to 4500 times the original volume. The higher the temperature of the barrel, the greater the expansion multiple.

"When a cold cannon is fired, that is, the first shot, it is generally 1800 times larger. After two or three shots, if the temperature is not lowered in time, the expansion coefficient will increase exponentially, and this is when it is most likely to explode.

"So every time you fire, you have to brush the barrel with a brush dipped in water. First, it is used to extinguish the unburned cloth scraps and embers from the previous shot to prevent the powder bag from igniting prematurely when reloading. Second, it is used to cool the barrel with water to prevent the barrel from overheating and causing it to explode."

"It can expand thousands of times?!" Tao Guangyi was immediately surprised, "But gunpowder is violent and unpredictable. How did Your Highness get this number of thousands of times?"

Lu Jin knocked on the table. "This will test your ability to design experiments. Let me give you a simple example. For example, you find a bamboo tube of uniform size, punch a hole inside, and use a paper ball as a plug. The weight is a few pounds. You can weigh a little less gunpowder, for example, one centimeter, and put it on one end of the bamboo tube to plug it. Then light it. Finally, see how far the paper ball plug is pushed out of the bamboo tube. Calculate the volume of this section of the bamboo tube. Isn't it the multiple of the gunpowder expansion?"

"It can be done this way, why didn't I think of it?" Tao Guangyi exclaimed that he had learned something new.

Lu Jin added, "The length of the gun barrel is usually calculated as a multiple of the diameter of the shell, that is, the length of several shells. For example, for a gun that uses black powder, the optimal multiple is 14 to 22 times the diameter. If it is shorter than 14 times the diameter, the gunpowder will not burn completely. When the shell is fired, the gunpowder has not yet burned out, and a huge flame will come out of the muzzle, which will also waste gunpowder.

"But if it exceeds 22 times the caliber, the gunpowder has burned out and expanded to the limit, and is no longer able to continue to accelerate the shell. If the barrel is longer, the remaining distance will only offset the speed of the shell due to friction, and the range will become shorter. So do you know how many times the caliber should be used as the length of the cannon?"

Tao Guangyi immediately drew inferences from his example and said, "I understand. Army artillery should have short barrels, as long as it is more than 14 times the diameter, which can bring out the best range of the artillery. The shorter the barrel, the lighter it is, which is convenient for accompanying the march. Naval artillery should have a barrel length of 20 to 22 times the diameter, which can bring out the maximum range and power." Lu Jin nodded with satisfaction, "You are a teachable boy, but most of our army field artillery is 16 times the diameter. The naval artillery I asked you to build, also known as the naval long gun, should have a barrel length of 18 to 22 times the diameter.

"Of course, other calibers can be used. For example, short guns with a caliber less than 14 cannons. Since the gunpowder cannot be completely burned, can the amount of gunpowder be further reduced? For example, a 10-caliber barrel can be loaded with gunpowder that is one-sixth the weight of the shell, and the lighter shrapnel can be fired.

"This short-barreled cannon has less charge, can be made short and thin, and is very light, perhaps weighing only 200 to 300 kilograms. A few people can carry it over mountains and ridges, so it can also be called a mountain cannon or a short-barreled howitzer.

"We can make cannons with a caliber of more than 22 times the diameter, but we have to use brown gunpowder that burns more slowly to increase the acceleration of the shells in the barrel and fire them at a longer distance. For example, with a caliber of 30 times and an elevation of 15 degrees, we can fire them more than ten miles away. However, this kind of cannon is too heavy and too long to be operated on a ship. It can only be used on a fixed turret, such as a fortress cannon guarding a naval port!"

Tao Guangyi's eyes lit up immediately after hearing this, "There is also this kind of brown gunpowder?"

"There are many kinds of gunpowder. There are black, brown, white, yellow, blue, green, transparent, oily, soapy, paste-like, and some that can start a big fire and not be extinguished by water, and burn through steel and emit poisonous smoke. They are many times more powerful than black powder. There are so many kinds."

"There are so many kinds of gunpowder?!" Tao Guangyi was stunned.

Lu Jin nodded, "Yes, but if you want to make these gunpowders, you have to learn chemistry first. Learn the basics of mathematics from your senior brother first. When I am done with my work, you can make the steam engine while learning chemistry from me.

"Also, I'll give you another assignment. Using the Gongshu Chi as the standard, start with a caliber of 30 mm and increase the model by five millimeters until it reaches 205 mm. Calculate the weight of shells of various sizes and the weight of the barrel at different calibers. Come back and write a table for me. This is something that an eight-year-old can calculate, so don't tell me you can't learn it."

Tao Guangyi suddenly felt a great deal of pressure and quickly agreed, "Don't worry, Your Highness. I will study hard."

"Yes." Lu Jin nodded and instructed, "Study mathematics well. The Mathematical Classic is the cornerstone of Gongshu Secret Canon. If you can't learn mathematics, you won't understand anything when I teach you physics and chemistry later.

"Especially learn how to make cannons. Making a steam engine is actually similar to making a cannon. The two are interchangeable. The barrel is the cylinder, and the cannonball is the piston. The cylinder diameter and piston stroke determine the power, torque and speed of the steam engine. If you learn how to make a cannon, you will also be able to make a steam engine."

Although Tao Guangyi didn't quite understand, he knew that the steam engine was similar to a cannon, so he nodded immediately and said, "Students must study hard."

"Go ahead, go take math lessons with your senior first."

"Yes, I will take my leave."

After the two men left, Lu Jin stared blankly at the list of research institutes of the two academies of science and engineering.

Not to mention the theoretical research institutes of the Academy of Sciences, the dozen or so research institutes of the Academy of Engineering were all carefully selected by him. None of them can be missing, but they can be in order.

For example, steam engines, chemicals, papermaking and printing are necessities for promoting basic education.

Historically, the paper production in the Southern Song Dynasty was about several million sheets per year, and in the Yuan Dynasty it was about 200 million sheets per year. The early Ming Dynasty experienced war and resumed production. By the 26th year of Hongwu (1393) in the early Ming Dynasty, 150 million sheets of paper were delivered to government offices everywhere. Together with those used by the public, it is estimated that the annual output was about million sheets.

But even this little bit of stuff is not enough to produce a modern paper mill in a few hours. The productivity gap is so huge.
In Lu Jin's current territory, the large-scale papermaking bases include Zhejiang's bamboo paper, with an annual output of perhaps hundreds of thousands of sheets; then there are Jingxian and Xuancheng in Anhui. These two places are the birthplaces of Xuan paper, which is the paper from Xuancheng, and the annual output may also be hundreds of thousands of sheets.

If we include Jiangxi, which is about to be occupied, Jiangxi is rich in mulberry paper, with an annual output of probably hundreds of thousands of sheets. But even if we include all these, there are only more than one million sheets of paper a year.

There are more than 4 million primary school students in the country. It's not enough to give one to each of them. What the hell is education?
Therefore, we need to develop steam engines, wood chippers, pulpers, and steam paper machines. The chemical industry must at least have the ability to mass-produce bleaching agents to compress the material preparation time of half a year for natural bleaching to a few days. So we need to set up a papermaking research institute so that we can produce enough paper. We also need a printing research institute to develop inks, plate making, and mechanical printing. Otherwise, all education and newspaper publishing will be in vain.

If you want to make these machines, you must first have machine tools, so this is a matter of tangling up the entire system.

There is also the steam engine. In the era when time travelers are prevalent in the future, many people have thought about making this thing, but Lu Jin often sees some comments on the Internet saying that the steam engine piston needs rubber seals. It's funny to see them. Don't think about the high temperature and high pressure working environment of the cylinder. You use rubber seals? It's still a moving part, and it has to rub back and forth with the cylinder wall. Are you sure the rubber won't melt?
When does the cylinder piston pass the rubber seal?
The earliest Newcomen steam engine had a very large tolerance and was sealed by wrapping hemp rope. By the time of Watt's reciprocating steam engine, metal processing technology had improved. Watt's cylinder was bored by the Carron Company, which built large-caliber carronades for the British Navy, using a cannon boring machine. The 60-centimeter diameter cylinder had an error of two millimeters, and the gap between the piston and the cylinder was large enough to fit a coin.

How did Watt seal it? The answer is that there is no need to seal it. For a cylinder with such a large diameter, a small leak would not affect the operation at all. In addition, the efficiency of early steam engines was low, and it was not expected to run very fast.

Later, in the era of steam locomotives, people had learned to use metal rings for sealing. They would machine a few grooves on the side of the piston and then put several layers of cast iron or brass sealing rings in. To this day, internal combustion engine cylinder pistons still use similar metal sealing rings. I have never heard of using rubber. Rubber begins to soften at 130°C, while high-pressure steam is over 500 degrees. The working environment is so hot, are you really not afraid of getting burned?
In fact, for Lu Jin, an engineer who studies mechanics and materials, making cylinder pistons is child's play. In comparison, the boiler is probably the most difficult part to make in the entire steam engine system. Before mastering the welding process, the key is how to use the rivet process to make a watertight and high-pressure container.

This is much more difficult than making a cylinder piston, but no one has ever mentioned it.
Fortunately, Lu Jin already had a solution in mind and was just waiting for Tao Guangyi, his tool-man disciple, to do the work for him.

However, by mid-July, Lu Jin had no time to think about this. The army was to set out in September, and there was only a month and a half left for preparation. He had to focus all his energy on fighting. Besides, the day for Lu Jin to offer sacrifices to heaven and be crowned king had also arrived!
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ps: Please give me a monthly ticket at the beginning of the month. There will be another chapter in the evening.

(End of this chapter)