Chapter 106: The Armstrong Cannon

The cannonball flew past the mound at 400 meters and smashed a pit 30cm deep in the ground. The iron ball at the bottom of the pit was still emitting blue smoke.

“The ground here is still relatively soft,” Lin Shenhe looked at it. “If the ground is hard enough, it can produce a ricochet effect, and the power will be even greater.”

Zhang Bolin began to pull the tape measure. From the 400-meter marker to the crater, the actual measured distance was 460 meters.

“The range is qualified,” Lin Shenhe was satisfied. “The accuracy is still satisfactory.”

“This is considered satisfactory? We didn’t hit anything!” Ying Yu found it incredible. This accuracy? This was a cannon, and it was direct fire.

“That’s right, smoothbore cannons are at this level. The enemy is in a dense formation, and this one shot can take out at least a dozen of them.”

Then they fired more than ten more shots with different angles and charges, with ranges from 400 meters to over 1200 meters. When the elevation angle reached the maximum of 45 degrees, the cannonball flew over 1500 meters. However, after the range exceeded 400 meters, the accuracy was completely gone. Basically, they could only see the general direction. A total of 4 mounds were hit during the whole process. The cannon became red and hot, but the barrel was very stable and there were no cracks. For safety’s sake, after firing fifteen times, Lin Shenhe announced a ceasefire and switched to another cannon.

“Still firing? I’m almost exhausted.” The artillerymen were all out of breath. The other things were fine, but the repositioning of the cannon after each shot was a laborious task. Moreover, there were always some problems with the direction and angle after repositioning, and they had to be readjusted, which consumed a lot of physical strength.

“We still have to use recoiling cannons, otherwise we’ll be out of breath.” Zhang Bolin was panting like a cow and almost collapsed to the ground.

“Recoiling cannons will have to wait until the industrial department produces springs,” Lin Shenhe was also tired enough. “Don’t even think about it before then.”

After a rest, they test-fired the cannon cast with a clay mold. The range was slightly shorter than that of the cannon cast with a hard mold, but the performance was not bad.

Subsequently, the artillery team used iron molds and the Rodman method to cast a variety of cannons of different calibers, including 12-pounder howitzers, 12-pounder mountain howitzers, and 12-pounder cannons. On the basis of gaining experience in casting light artillery, they began to cast 32-pounder cannons and 32-pounder carronades for the navy [Note: This is a direct-fire short cannon invented and used by the British Navy]. All these various cannons were successful in the test firing. The area around Lingao Cape was filled with the roar of cannons and smoke all day long.

After accumulating enough casting experience, the artillery team, based on the drawings and instructions of the Armstrong cannon in the database, designed an improved version of the Armstrong cannon with a threaded breechblock.

A rifled cannon is not the same as a smoothbore cannon. Although the caliber of the long cannon (cannon) had reached 120mm when the artillery team was casting the 32-pounder cannon, the designers of the artillery team cautiously set the caliber of the first Armstrong cannon to 70mm.

The material of the cannon was cast steel. Casting was no longer difficult for the artillery team, who were already familiar with it. The main problem was the processing of the rifling. In an arsenal, this required special machines, or at least special tooling. It was too late to build them right away. Fortunately, the transmigrators had predecessors to learn from—the military-industrial soldiers of the Eighth Route Army and the New Fourth Army, who also made rifles and cannons under the simplest mechanical equipment and manual conditions. By consulting the materials, Zhan Wuya decided to imitate a native method of extruding rifling used by Wu Yunduo when he made a direct-fire cannon, that is, using an olive-shaped steel column with concave and convex oblique lines carved on the circumference, and then wedging the steel column hard into the barrel.

How to make this steel column, Wu Yunduo only gave a general idea, without specific drawings. The artillery team gathered all the talents who understood machinery and drafting, and held a meeting overnight to study and draw the design drawings. Jiang Ye was in charge. They first used sand casting, and then used a lathe to turn the steel mold.

Finally, this extrusion method proved to be effective. A few days later, the barrel of the first Armstrong cannon was processed. The breechblock was a little difficult, but with the joint efforts of Jiang Ye and Xiao Bailang, the threaded breechblock was finally completed and successfully installed. The assembled and polished cannon looked smooth and shiny. Everyone looked at it and touched it with a lewd look on their faces.

The projectile was a long-pointed solid shot made of cast iron, but the fuze of the rifled cannon projectile was very difficult to solve.

Regardless of whether there was a safety device, the basic structure of the fuze was a spring-loaded firing pin. This required two things: a fuze and a spring. Compared with the mercury fulminate used in the fuze, the spring was a big problem they faced. The manufacture of the spring itself was not difficult, but the material was—modern springs are generally made of alloy steel, which cannot be produced with a small converter. The machinery group had a reserve of spring steel, but the cannon fuze was a consumable and could not be made with reserved materials.

“How about a chemical fuze?” Zhang Bolin had a sudden idea.

“How so?”

“Use a chemical reaction to detonate the shell,” Zhang Bolin’s idea was very simple: use a small bottle of glass or porcelain, filled with a chemical, surrounded by another chemical that can react violently with it. When the shell is hit, the glass bottle breaks, and the two chemicals mix and react violently, detonating the explosives in the shell.

“Not very safe,” Xiao Bailang said. “The shells have to be moved and transported constantly. What if the glass bottle breaks?”

“Transport them separately. The fuze and the shell are transported separately, and they are assembled when they are to be used.”

Wang Luobin shook his head repeatedly: “This idea is good, but you forgot one thing: the chamber pressure of a breech-loading rifled cannon is much greater than that of a smoothbore cannon. The fuze must have sufficient strength. The glass tube will definitely break at the moment of firing, and the result is—a burst chamber.”

Zhang Bolin was dumbfounded. He had never thought about this problem.

“How about it? Cannons are not as easy to play with as you imagined, are they?” Ying Yu patted him on the shoulder.

“It’s not impossible to use this fuze on other explosives,” Lin Shenhe said, “but it’s absolutely not possible for cannon shells.”

“It seems that having advanced cannons is not enough.” Wang Luobin smiled bitterly. The bursting shell of a smoothbore cannon had no technical difficulty, but this technology could not be used on a rifled cannon.

“Carbon steel can also be used to make springs.” Jiang Ye thought for a long time and recalled that he seemed to have seen springs made of carbon steel.

“Yes, 0.6% carbon steel can be used. I just don’t know if the performance is good enough,” Ji Wusheng said. “We can try it. I’ll check the book to see how the heat treatment is done.”

“Can you do the heat treatment?” Zhan Wuya was not sure himself. He had only done some simple jobs with a heat treatment furnace.

“I’m not sure either. I can only rely on checking books and experimenting.”

“This is probably not a simple matter. It can’t be done in a day or two.”

Several people thought hard for a long time without any result. In the end, it was Lin Shenhe who proposed that since the first batch of Armstrong cannons was for the navy, anti-ship warfare was still dominated by armor-piercing projectiles, and solid cast iron projectiles would be sufficient.

“What about shore bombardment missions?”

“Use mortars,” Lin Shenhe said.

Mortars were the predecessor of mortars, and the manufacturing technology was much simpler than that of mortars. The accompanying high-explosive shells were also very easy to manufacture. The disadvantage was that the dud rate of the high-explosive shells was relatively high, and it could only be said that it was better than nothing.

“How to solve the problem of lead plating?” Wang Luobin asked. Historically, the Armstrong cannon was kicked out of warships by the British Navy because the lead sheets on the projectile flew off and caused casualties at the moment the projectile left the muzzle.

“I read in the materials that someone at that time proposed that electroplating lead would not cause this problem—” Lin Shenhe explained the solution he had mastered.

The early rifled cannon projectiles used a technology similar to the Minie rifle bullet, which used the explosive gas to expand the base of the projectile and embed it into the rifling. Therefore, the outside of the projectile must be wrapped with a soft metal, and lead was the most suitable metal. The problem immediately followed—the combination between the cast iron projectile body and the lead skin was very difficult, especially in the absence of a hydraulic press. The result of a forced combination was the same as the Armstrong cannon of the Royal Navy, with the lead skin flying off.

“Electroplating is too extravagant right now, and the technology is not good enough,” Zhan Wuya said.

“There is a line of thought, I don’t know if it is feasible. It was used on the projectile of the American 3-inch Shenkl cannon back then.”

Since the lead skin falling off was easy to injure people, and they had no way to prevent it from falling off, the best way was to replace it with something that would not injure people even if it flew off.

The projectile of the Shenkl cannon was to surround the lower half of the projectile with paper-mache, which was a driving band made of concrete pulp. It had enough strength and toughness to be embedded in the rifling, and it would not injure people due to fragmentation and flying off when it left the muzzle.

“Is this concrete pulp difficult?”

“1860s technology, it shouldn’t be difficult, right? It’s nothing more than pulp and glue. There is no ready-made formula for this, so we can only rely on the experimenters.”

“This task can be handed over to the chemical group. They have experience with this.”

As they were talking, He Ming of the military group suddenly rushed in with a serious face.

“What happened?” Wang Luobin had a bad feeling.

“According to the confession of the prisoner, the pirates are very likely to attack us recently!” he said, handing over a document. “This is the interrogation report issued by the security team.”