Part 249: High-Explosive Shell Test

In terms of manufacturing quality, the fuzes made by the naturalized workers were no worse than those made by the Senators. The difference in detonation rates was negligible. It seemed Lin Shenhe’s efforts to simplify the fuze’s design had paid off, allowing less-skilled naturalized workers to produce acceptable products.

As for safety, tests confirmed that as long as the safety pin was not removed, the fuze would not accidentally detonate even when dropped from a height of 12 meters onto the ground.

However, the ordnance team was not satisfied with just this. Any industrial product must not only meet functional requirements but also be cost-effective and suitable for mass production. As a consumable item, the fuze needed to be as cheap and easy to produce as possible. While phosphor bronze springs could be produced domestically, they were considered “high-grade precision components” in Lingao’s industrial system, classified as a “Level 2 Controlled Material” by the Planning Commission.

Currently, phosphor bronze springs were mainly used in more precise industrial equipment, such as the timers and instruments that Dr. Zhong was wholeheartedly developing. Their production cost was high.

It would be best to find a cheaper, more readily available material to replace it. After much consideration, Lin Shenhe went to see Zhan Wuya and asked if he could heat-treat wrought iron wire.

“Of course, but what do you need heat-treated wrought iron wire for?” Zhan Wuya was puzzled.

“For springs—to be used in artillery shell fuzes.”

Zhan Wuya looked at him in disbelief. The problem of springs for artillery fuzes was a long-standing obstacle, and now Lin Shenhe was telling him he wanted to use heat-treated wrought iron wire!

The Industrial and Energy Committee produced wrought iron wire of various gauges according to old-world standards, with higher grades even being galvanized. Wrought iron wire had a wide range of uses in the Senate’s industrial and agricultural production; Lingao Telecom’s telegraph lines were also laid with it.

Lin Shenhe showed him a model of the fuze’s structure—a scaled cross-section model he had commissioned from the machine shop—and explained its operation and principles in detail. Zhan Wuya studied it for a long time and finally agreed to try using iron wire.

They selected No. 20 galvanized wrought iron wire. They used a special spring coiling machine to form the wire into springs and then heat-treated them.

Afterward, Lin Shenhe conducted comparative tests on the iron wire springs and the phosphor bronze springs using his testing equipment. He knew it was impossible for the two types of springs to have identical performance. The results, of course, were as he expected.

“It seems it can’t be a substitute,” said Zhan Wuya.

“Let’s try firing them in a cannon,” Lin Shenhe said, not ready to give up.

Shells with fuzes using the iron wire springs were successfully fired from a howitzer with a heavy charge. Both their safety and detonation rate were no worse than those with phosphor bronze springs. However, their performance in the 70mm cannon was poor, with the springs failing multiple times. The high chamber pressure of a cannon like this put the fuze to a much more severe test.

Lin Shenhe was satisfied with all the test results and decided to proceed with live-fire tests using actual explosive charges.

The black powder charges that had been sent to dry were now all naturally dried. The final step was to coat the surface of the charges with an alcohol-based shellac varnish of a certain concentration. This served both to prevent moisture absorption and to stop them from cracking or deforming.

Shellac was imported from India and Vietnam, a resin secreted by the lac bug. It had a wide range of industrial applications, and for an industrial system like Lingao’s, which lacked chemical products, the importance of shellac as a natural resin was even more significant.

The weapons enthusiasts in the mechanical department began to fill the shells. The highly compressed black powder charges could no longer be simply ignited with a fuse; they required a detonator—a blasting cap.

Manufacturing detonators was a considerably dangerous task, though not technically difficult. The process involved rolling kraft paper into a tube, pressing the primary explosive into the tube with a press, and then sealing it. To reduce the risk, the ordnance department had rarely made detonators in the past. Explosives based mainly on black powder generally didn’t require them. Detonators were only produced in small quantities when using dynamite or ammonium nitrate explosives.

The warehouse of the First Research Center of the Special Chemical Industry Complex stored a small number of detonator casings and safety caps. The detonator casings were made of rolled kraft paper, coated inside and out with an alcohol-based shellac varnish for moisture proofing. Lin Shenhe personally selected twenty of them for the experimental shells.

Common detonators were either simple or compound. Simple ones contained only fulminate of mercury, while compound ones had fulminate of mercury on top and a booster charge—usually TNT or RDX—below.

Because the chemical department couldn’t produce TNT, all the detonators made by the ordnance department in the past were simple detonators. This time, to ensure effective detonation, Bai Yu suggested making compound detonators, but Lin Shenhe objected—no matter how capable they were, they couldn’t conjure TNT out of thin air.

“We can use the stock of ammonium nitrate explosives. Besides, don’t we still have the explosives Lan Du brought?”

“That’s pointless. We can’t mass-produce either of those yet. We should conduct our tests based on what our industry can produce in bulk.”

In the end, they decided to continue making simple detonators. In the detonator workshop, Lin Shenhe carefully loaded the fulminate of mercury into the casing in several small portions, then gently compacted it with a press. For safety, he stood behind a thick steel plate and wore an EOD helmet. Fulminate of mercury is extremely sensitive and can easily explode during pressing.

After the fulminate of mercury powder was pressed, he took a safety cap made of galvanized iron sheet—which held a thin silk membrane inside—and placed it on the casing. He turned the handle of the press.

According to the technical specifications, the press applied a force of … kilograms per square centimeter to press the safety cap into the casing. Lin Shenhe checked if the seal was complete, then carefully brushed off any scattered powder from the casing, collecting the stray fulminate of mercury into a waste container. Finally, he applied a drop of shellac varnish to the bottom of the casing, and a detonator was complete.

Next, they conducted another detonator test at the firing range. The new detonators were fitted into fuzes and subjected to a firing test under realistic conditions to ensure the fuze’s firing pin could effectively set off the detonator.

The first attempt failed—the firing pin was not properly aligned. Jiang Ye adjusted it on the spot, and the second attempt was an immediate success. They repeated the test several times, and each time the detonator was triggered correctly.

Lin Shenhe nodded. “We can proceed with assembly now.” He signed the assembly work order, officially commanding the assembly of high-explosive shells equipped with the new fuzes.

The time had finally come for the new fuze’s official debut. The 70mm rifled cannon borrowed last time was still at the firing range. Lin Shenhe also borrowed a 24-pounder smoothbore howitzer—with no mortars available and howitzers not being a perfect fit, this would have to do for now.

“Can conical shells also be fired from a smoothbore cannon?” Zhan Wuya asked.

“Of course,” Lin Shenhe said. “Mortars don’t fire spherical shells either.”

A simple railway track had been laid at the firing range, and a railcar transported 40 newly produced high-explosive shells for the two cannons: half with phosphor bronze springs and half with No. 20 wrought iron wire springs.

“24-pounder howitzer, one Type A shell, load!” Lin Shenhe commanded from inside a bunker, using a large sheet-metal megaphone. A gun crew from the Army Training Division quickly opened a wicker ammunition box, took out a shell, and fitted the fuze. One gunner loaded a silk powder bag into the muzzle, and the loader followed with the shell.

The gunner inserted a friction primer into the touch hole at the rear and attached a lanyard. For safety, the lanyard was very long, stretching over 20 meters to the bunker.

With a whistle, all the gunners ran to the bunker and jumped in. Then, the warning siren for live-fire exercises echoed across the area.

“Fire!” Lin Shenhe yelled, then quickly ducked back into the bunker, putting his eyes to a pair of binocular periscopes newly made by the optics workshop.

The gunner gave a sharp pull on the lanyard. The 24-pounder howitzer let out a roar, its heavy body recoiling as it spewed white smoke. Through the periscope, he could see the trajectory of the shell as it flew through the air—the combination of a smoothbore cannon and brown powder resulted in a rather low muzzle velocity.

The shell landed precisely in the designated target area, and with a flash of light, it exploded!

The force of the explosion, even to the naked eye, was clearly much stronger than that of the primitive spherical black powder shells—those shells only produced a puff of black smoke upon landing and kicked up very little dirt.

“Let’s go take a look.” Lin Shenhe quickly climbed out of the bunker. He, along with Jiang Ye, Wang Ruixiang, and a few apprentices from the ordnance department, climbed onto a farm vehicle and bumped along the dirt road towards the impact zone.

The 24-pounder shell had left a crater half a man deep. Smoke was still rising from it, and the pungent smell of black powder filled the air. Lin Shenhe knelt and sifted through the dirt at the edge of the crater. Several students interning at the First Research Institute quickly spread out, searching for shell fragments and marking their locations on a chart.

“Look,” he said, pointing to a fragment he had picked up. “The more powerful charge means the shell shatters much better than before.”

Not only did the fragments fly farther than before, but the degree of fragmentation was also much greater than with the spherical shells. The old spherical HE shells would break into about twenty large pieces upon exploding, sometimes as few as seven or eight, failing to create a dense, lethal fragmentation pattern. Even the large-caliber howitzer shells with the heaviest charges couldn’t produce more fragments.

Now, a simple search had found over seventy fragments of various sizes within five meters of the crater. Lin Shenhe pointed out that if they could further improve the shell’s body material and implement pre-scored fragmentation, the effect would be even better.

The twenty shots with the Type A fuze (phosphor bronze spring) were all successful in both cannons. In the test with the Type B fuze, all shots from the 24-pounder smoothbore were successful. However, on the third shot from the 70mm rifled cannon, the people in the bunker just saw a flash of light, heard a massive muffled boom from the ground, and felt a slight tremor—the shell had exploded inside the barrel.