"Twenty days?" Zhu Youzhen wondered in his heart, not long after the king of Chenzhou came out of Fujing, where did he get so many heavy artillery? Even if he went to buy it from the Yi people, and the Yi people happened to have cannons to sell him, it would be impossible to transport them from Macao or Dongfan to Ganzhou within twenty days.

Yang Tinglin had no other way, so he simply bet the treasure on the king of Chenzhou, and waved his hand and said: "The king of Chenzhou is righteous for the country, and the officials are deeply admired. With these heavy artillery, the King of Yongning and His Royal Highness the King of Luochuan will kill the king Deren like killing chickens and dogs. ”

Zhu Youzhen was stunned for a moment, although he felt that something was wrong, but he couldn't change his words when he was in a hurry, so he patted the armrest of the seat hard, "That's good, if the eight thousand-pound Hongyi cannons are ready within twenty days, the army will go north to Ji'an Mansion." ”

He looked at Yang Tinglin, and changed his words, "But if the heavy artillery is not available, I hope that Yang Butang will not delay the military aircraft again, and immediately wave his army to Jianchang." ”

Yang Tinglin had no way to retreat at this point, and nodded vigorously: "Just according to what King Yongning said!" ”

Seeing Zhu Youzhen and Zhu Youling turn around and leave the big tent, Yang Tinglin only felt that he had nothing in his heart, and hurriedly asked Su Chengyu: "Where is this cannon now, Your Highness?" Do you want the officials to help you? ”

Su Chengyu smiled: "I really have something to ask you to help with." ”

"Your Highness, please speak, your majesty should do your best."

"The Ganzhou Ordnance Bureau lends me a favor."

Yang Tinglin personally returned to the Ordnance Bureau with Su Chengyu and ordered all the officials to be dispatched by His Royal Highness the King of Chenzhou.

In fact, until now, he didn't know how Su Chengyu was going to take out these eight heavy cannons, and he had asked many times along the way, but Su Chengyu replied with a smile, "Mountain people have their own clever plans."

Xu Erlu didn't expect His Royal Highness King Chenzhou to come back so soon, and he was even more surprised that he actually said that he wanted to cast a cannon!

Xu Erlu took Su Chengyu to the depths of the Ordnance Bureau, and introduced him to the basic situation here along the way, the Ordnance Bureau has 620 military craftsmen and ordinary craftsmen, of which more than forty percent are responsible for making artillery. Another forty percent were responsible for other firearms, and the rest of the craftsmen made bows, crossbows, gunpowder, and the like.

Then he asked cautiously, "What kind of cannon does Your Highness want to cast?" ”

"Twelve-pounder batter." Su Chengyu replied. He can casually say some later terms such as "cannon" to a layman like King Yongning, but this Xu Erlu should be an expert, so he used the standard classification of artillery in the Ming Dynasty.

The attack cannon here refers to a cannon with a medium barrel.

Xu Erlu immediately said: "What the Ordnance Bureau is making now is a twelve-pound cannon, using the pattern of the Francophone man. ”

It turned out to be the plan of the Portuguese, no wonder he was so familiar with the concept of twelve pounds, Su Chengyu nodded, "It's better to have ready-made technology." But I'm going to forge eight twelve-pounder cannons in twenty days, so there are some things that need to be improved. ”

"Eight Gates?!" Xu Erlu was surprised, "With the current ability of the Ordnance Bureau's artillery field, it may be ...... in half a year."

While speaking, the two of them and their entourage have walked to the artillery field, surrounded by tall wooden frames, which are full of pulleys and iron cables, and the copper liquid is tumbling in the huge furnace, and the heat wave can be felt from a long distance.

It is not accurate to say that the house is extremely tall, because more than half of the roof is open and open.

The hot copper water flowed into the buried clay molds, and someone shouted loudly from the side, slowing down the artisans who controlled the dumping. After a while, the pouring is completed, and a circle of people come up to put the finishing touches on the flat mold and mulching.

On the other side, there was a burst of cheers from the craftsmen. Underneath the huge triangular wooden frame was a pile of crumbles, and a bronze cannon more than one person high stood in the center. The barrel of the cannon was lined with wooden planks, which were fixed with iron cables and suspended from a triangular wooden frame to prevent the copper cannon from tipping over.

The lower part of the bronze cannon is still wrapped in two pieces of mud, and some craftsmen are carefully breaking the mud blocks, and as the mud skin continues to peel off, the people next to them cheer again.

Xu Erlu hurriedly explained to Su Chengyu: "It seems that this cannon has no obvious flaws, so the craftsmen cheered and celebrated. Casting cannons often depends on luck, and nine out of ten times they are scrapped. However, it will be a complete success if it does not explode the chamber and test fire it a few times. ”

Su Chengyu has seen this many times on the forum. In this era, the casting process was to use special clay to make a cylindrical inner core, and then make a cylinder outer fan, and bake the two together, and the mold was ready. Then pour molten iron into the gap between the inner core and the outer fan, and after solidification, knock the mud mold and take out the iron cannon.

After that, the front part of the muzzle is sawed off, and since the pouring is carried out at the muzzle position, there will be irregular copper overflow from the muzzle. All to be sawed off a small section, then sanded flat.

Then the process of polishing the gun chamber and drilling the fire door is carried out, and one gun is counted. Usually the last two steps alone take more than ten days.

And because the mold made of clay has low air permeability, it is difficult to dry thoroughly, and moisture will be generated when casting molten iron, and the moisture will become a porous hole on the cannon body, so this method often has honeycomb holes in the casting cannon. Once this hole is created, there is a high chance of exploding when firing.

In addition, the inner core of the clay fan may be slightly crooked when pouring the molten copper, and no one can detect this deviation until the clay fan is peeled off. It probably took a lot of work to know that the cannon was unusable when it was cast.

So it really takes a lot of luck to make a good artillery.

"This month, we have made one Hongyi heavy artillery and two No. 4 Furlong machines, which are not bad." Xu Erlu showed a hint of relief, "I don't know if this cannon that was out of order just now can pass the test firing." ”

Su Chengyu saw that there were seventy or eighty craftsmen not far away who were making clay fans very carefully, and some people dragged the freshly made clay fans to a ventilated shed to dry, and he hurriedly said to Xu Erlu: "Let the craftsmen, especially the craftsmen who make the fans, stop their work." ”

Xu Erlu was stunned for a moment, and immediately asked, "Your Highness, why is this?" Immediately remembering Yang Tinglin's instructions, he immediately asked people to inform the craftsman.

"We use a new process to cast cannons." Su Chengyu smiled mysteriously and said, "Find a few more craftsmen with the best skills." ”

"Yes, Your Highness."

A moment later, Su Chengyu, Xu Erlu and several craftsmen gathered in a wooden shed. Su Chengyu first said the goal, "We want to use an iron mold, oh, it is an iron fan to cast a cannon." Only in this way will it be possible to cast eight heavy cannons in twenty days. ”

"Tiefan?" Xu Erlu and the craftsmen looked at each other.

However, a craftsman whispered: "The blacksmith in my hometown used to use iron to make farm tools, but this cannon is ......."

"That's right." Su Chengyu immediately encouraged, "The truth is the same. It's just that everyone used to be accustomed to the Yiren clay fan craft, but they didn't expect to replace it with an iron fan.

"There are many advantages to casting with iron fan, first of all, iron fan can only be used once like clay fan, and iron fan can be cast at least fifty or sixty times after it is made.

"Secondly, the iron fan does not store water vapor like the mud fan, so the cast cannon will not have pores, and the yield will be very high.

"In addition, because the iron fan itself is smooth and flat, the gun chamber after taking off the fan is also smooth, and there is no need to polish the gun chamber."