Fanning sat on a small stool in the cannon foundry, silently arranging his tools. As a well-known bell maker, the 50-year-old has been working here for more than three years.

In the past three years, there have been more than ten cannons cast by him, and his experience can be regarded as rich, so he sat at the head of the third group, and the personnel under him were all convinced.

As an old comrade, Fanning was rated as a fifth-level worker by the person in charge of the workshop, and his basic monthly salary was ten yuan. But he is also the head of the team, which will add another ten dollars.

Then counting their group's performance salary, as well as task rewards, it was easy for Fanning to get thirty or fifty times.

Compared to the previous days, this is a super lucrative treatment.

It's a pity that he has a very lively brain, but he gave birth to a stupid son, his only son Fan He, has been in the factory for two years, but he is still only a second-level worker, and his basic monthly salary is only four yuan, and the most one month has not exceeded ten yuan.

So Fanning is not complacent at all because of his achievements, and he is still sincere and serious every day.

He hopes to save more money for his children and grandchildren before he retires, and he hopes that he can go one step further so that he can send his grandson to a technical school run by the Ministry of Industry.

As long as he sees his son, Fanning knows that he has no capital to 'enjoy'.

In addition to him, there are more than 20 people in the three groups. However, half of them are rookies with no experience, they are either students of technical schools, or descendants selected from the bereaved families of martyrs, except for being smart, they are clumsy in what they do. Even when it matters most, they can only add to the chaos.

But even so, Fanning had to endure it. Because these people are the descendants of the imperial court.

Fanning was packing up his tools, thinking about things in his heart.

The inch is long, and the ruler is short.

The people who came out of the technical school have a lower level in their hands, but they are all very polite, and they are really not the straw bales and rice buckets with empty stomachs, and they can still put forward some unbelievable ideas for specific problems.

The strategic target of the third group was not small artillery, but medium artillery with 10 pounds of ammunition. In the plan of the Governor's Office of the Five Armies, the cannon of this specification is already the main gun on the warship.

At the same time, it can be regarded as a heavy artillery in land warfare, and it is a weapon for destroying enemies against city fortresses.

Therefore, for this kind of artillery, as well as the evolved twelve-pound cannon, the requirements of the Governor's Office of the Five Armies, in addition to being powerful, must be durable and 'accurate', and must not be too heavy, and must have a certain ability to move in the field.

That's the trouble.

The cannon, after several years of casting and experience summary, is a thing that everyone knows that if it wants to fight far and for a long time, it must be heavy first.

Only the thicker the barrel and the larger the diameter, the greater its power. It is also true that the thicker and heavier the cannon wall, the more durable it will be.

That's why the Manchu Qing Dynasty in history will have those generals' cannons weighing 10,000 catties.

However, with such a heavy gun body and ammunition boxes, the movement speed in land combat is infinitely close to zero.

It's not that it's so heavy that it can't move, but that on the battlefield, in the face of unpredictable battle situations, such a heavy cannon is too flawed.

So it's a paradox.

Fortunately, the materials used by the three groups to cast their guns were not only cast iron, but also a large amount of bronze and brass.

Experimental results show that the bronze cannon is much lighter and more durable than the cast iron cannon under the same power. But the cost of the copper cannon is obviously much larger than that of the cast iron cannon.

At the same time, all the cannon casting teams have the same problem - that is, how to reduce the scrap rate!

Clay mold casting cannon is a technique that has been used by the cannon casting group since the beginning, and it comes from the casting process of bronze bells.

The work efficiency of this casting method is not high, and it takes a considerable time to pour the mold repeatedly, and the molded clay mold needs a lot of time to do the dry treatment. It usually takes several months to forge a cannon.

This thing (clay mold) can't be dried or baked. Clay molds made of clay are prone to drying and cracking when dried or baked. Once it dries out, the clay mold is wasted.

When casting the cannon, once the water in the clay mold is not completely dry, the water vapor in the clay mold will precipitate out when the molten iron is forced by the hot air during casting, and the cast cannon body is prone to pores and other honeycomb tissues, resulting in the complete failure of the casting cannon.

Clay mold casting cannons, casting 10 can be successful, it is already a high proportion.

Zhao Gou has naturally heard of the iron mold casting method, as an old white at the starting point, the iron mold casting method has not known how many books of history have appeared.

But he didn't give any hint to the Cannon Casting Bureau.

This method, like the Mini rifle, will become the secret treasure of the Great Song Dynasty to suppress the national fortune, and it will be quietly passed on to future generations by him.

In this era, just the results of clay mold casting cannons are already invincible in the world.

Zhao Gou doesn't need to blindly upgrade firearms.

That would only destroy Zhao Song's leading position.

Because the Mini rifle and the iron mold casting method are not too high-tech, after the firearms spread all over the world, they will be quickly learned by others, which in turn threatens the safety of Zhao Song.

Therefore, the casting bureau, which is deeply trapped in the category of clay molds, really has no clue about the current process improvement.

There were also two long-barreled guns cast in the workshop of the three teams, and their performance was not bad, and the range and accuracy were improved compared to the previous finished product. But the weight is also growing.

Therefore, the most important point for the three groups now is to come up with the most appropriate model.

What is the size of the double diameter of this ten-pound cannon (twelve-pound cannon) and is the most suitable?

- The double diameter refers to the ratio of the length of the barrel to the caliber of the barrel, and the greater the multiple diameter, the greater the range and relative accuracy.

But as the leader of the three teams, Fanning also has to think about the improvement of the process.

Two days ago, a kid who graduated from a technical school put forward an idea.

Although Fanning focuses on the formulation of the double diameter, he still has to free his mind to consider the process.

In the past three years or so, more than 100 large and small artillery pieces have been cast.

And scrapped is more.

Among the latter, there are not only a lot of scraps that are born with congenital disabilities, but there are also many products that look fine on the outside, but will explode once the gun is tested.

The kid thought that this was because the inner and outer walls of the barrel were cooled unevenly, resulting in invisible cracks in the inner wall of the barrel, so it was useless.

To be sure, Fanning thinks this conclusion makes sense.

When the cast barrel is cooled, the outer wall of the barrel is larger than the inner wall, and the air circulation on the surface is faster than that of the inner barrel, which naturally causes the outer wall to cool faster than the inner wall.

The larger the caliber of the gun, the more likely it is to have such a problem, because the larger the caliber of the gun, the larger the area difference between the inner and outer walls of the barrel, and the difference in cooling speed will naturally become larger and larger, which may really cause hidden cracks in the inner wall of the barrel. Wouldn't such a cannon explode when it was test-fired?

But if the truth makes sense, how can it be solved?

Although Fanning had already reported to his superiors, he still wanted to solve the problem on his own.

Because you can know with your heels that if this is really done, it will make a great contribution to the imperial court.