Chapter 59
“Creating the sneak bomb in the original way was too inefficient.”
The original sneak bomb used a whole, casted sphere. By the 21st-century standards, this method had many issues. Of course, the technology involved in creating a hollow spherical shape was admirable, but it wasn’t a particularly recommended method in terms of production efficiency.
“When you look at the performance, ‘mass production without questions’ would obviously be better, you need a strategy.”
The first step Hyang took was to divide the sphere of the sneak bomb in two.
Hyang changed the design so that one-half of the divided sphere would have a female screw and the other half a male screw. By matching and turning the engraved screws on the two halves, the two halves would become a complete sphere.
Hyang also applied screws to the part where the fuse is inserted and the hole where the gunpowder is inserted. The idea was to make it even more secure by engraving screws on the cap that covers the fuse and the cover that seals the hole after the gunpowder is inserted.
Hyang then conducted a firepower test with the prototypes made this way.
“First, let’s try without the launching process from the weapon.”
“Yes, Your Highness.”
As a result of the test, the improved sneak bomb exploded wonderfully, as Hyang expected.“That’s incredible!”
“How about we send this to the North right away?”
Looking at the testing area turned into a mess, Lee Chun and Choi Hae-san couldn’t help but marvel. However, Hyang, smiling, shook his head.
“We still have many things to test. We should start with the launching test.”
“Launch… Right. I forgot about the ‘non-standard’ part.”
In the ensuing launching test, the non-standardized sneak bomb was safely launched. Hyang, having confirmed the result, moved on to the next task.
“Now, I should report to the King and arrange for…”
“Alright! Shall we try reducing the thickness of the shell? Let’s start by decreasing it by a dolly (about 1.5mm) each time.”
At Hyang’s command, the artisans started making prototypes with the shell thickness reduced from a dolly to 4 hal (4/10ths of an inch, about 1.2cm), in increments of 5 ri. This was literally a process of trial and error.
“When we launched it from a weapon with twice the amount of gunpowder, the thinnest surviving shell from launch to impact was the one we shaved down to 3 hal (about 9mm).”
“Now, shall we try filling it with gunpowder and testing?”
“Yes, Your Highness.”
In the ensuing test, the non-standardized sneak bomb, shaved down to 3 hal, survived the repeated impacts of launch and landing and exploded properly. Seeing the results, Choi Hae-san and Lee Chun became greedy again.
“Since the results are good, should we report…”
“The blast radius is too wide. There’s a risk of our allies being hit. Let’s look for ways to increase the lethality while reducing the blast radius.”
“You are right, Your Highness. We will consider it.”
Upon hearing Hyang’s command, Choi Hae-san, Lee Chun, the officials, and the artisans began looking for various strategies. However, it was hard to find a way to satisfy the contradictory conditions of ‘strengthening lethality’ and ‘reducing danger radius’ at the same time.
Eventually, Hyang had to step in again.
“Bring me clay and paper, and chicken egg-sized iron beads.”
“…Yes, Your Highness.”
When the artisans brought the materials, Hyang gave them orders.
“Coat the inside of the non-standardized sneak bomb’s shell with clay, about a half-inch thick, and embed the iron beads all over it. Then, once the clay dries, apply paper to keep it securely fastened so it doesn’t fall off.”
Upon hearing Hyang’s command, the officials and the artisans let out exclamations of admiration.
“Ah! That’s the solution!”
In the subsequent test, the improved non-standardized sneak bomb had a reduced danger radius compared to the first version, but its lethality was even greater. Hyang, who was examining the results, looked back at Choi Hae-san and Lee Chun.
“Let’s try to improve it a little more. Just a bit more…”
“Yes, Your Highness.”
In the subsequent second phase of the improvements, the artisans and Hyang etched gold into the interior of the non-standardized sneak bomb in a pattern resembling a Go board. They also layered in additional explosive charges.
A Go board
After the second improvement phase, Hyang observed the results of the following tests and ordered Choi Hae-san and Lee Chun.
“I think this is sufficient. If we push any further, future generations will view us as bloodthirsty and ruthless.”
“I agree!”
At Hyang’s words, Choi Hae-san and Lee Chun nodded vigorously. The scene created by the improved non-standardized sneak bomb was a genuine slaughter.
“Now for the report…”
“Now let’s improve the cannon that launches this sneak bomb.”
“Excuse me?”
At Hyang’s words, Choi Hae-san and Lee Chunn looked depressed.
Hyang observed the Daewangoo (large bowl-shaped cannon) that fired the non-standardized sneak bomb.
“The amount of gunpowder that enters the powder chamber is 35 yang (approximately 1.3 kg)… The problem is that it’s not an efficient design.”
What Hyang pointed out was the overall design of the cannon.
“Let’s change the structure!”
Hyang redesigned the cannon that fired the non-standardized sneak bomb into a traditional linear form. He created a cannonball similar to those used on Western cannons of the 18th and 19th centuries.
“Is it too Western-style? I don’t think so.”
Looking at his sketch, Hyang chuckled. More accurately, the design Hyang created was closer to the medium-sized infantry cannons created during the Daewongun1 era in Joseon.
Hyang hung up the drawing of the cannon and cannonball he had envisioned and exchanged opinions with Choi Hae-san, Lee Chun, and the artisans.
“Mount it on a large-wheeled cart. The mobility will improve.”
“Considering our battles with the northern Jurchen tribes, wouldn’t it be much easier if the cannon was mobile?”
At Hyang’s words, Choi Hae-san and Lee Chun nodded. Having ample combat experience from both the south and north, the two men were able to understand the advantage Hyang was talking about immediately.
Lee Chun, who was looking at the drawing, drew a conclusion. “If we create a cart carrying the cannon and another cart carrying the bombs and gunpowder… Even if the non-standardized sneak bomb only travels with two wheels, the Jurchens would not dare to act rashly.”
As Choi Hae-san and Lee Chun, who could be called the top experts in the Joseon military on cannons, agreed, the development of the cannon and cannonball progressed rapidly.
A distinguishing feature of the newly developed cannon compared to the existing ones was that the back part of the internal powder chamber was round, as well as its exterior.
“General Choi, do you remember when we first tested the explosion?”
“Yes.”
“At that time, we saw that the burns created on the copper plate radiated outwards. I think this suggests that when gunpowder explodes, the force radiates outwards.”
Choi Hae-san, who had been pondering Hyang’s words, nodded his head. “That seems likely.”
“If so, wouldn’t the cannon become much stronger if we hollow out the back of the powder chamber like this? It would have the same thickness at any angle.”
Choi Hae-san, who had been carefully examining the blueprint, nodded his head. “It seems worth trying.”
After the first cannon was manufactured, Hyang and Choi Hae-san immediately began testing.
They placed double the normal amount of gunpowder in the powder chambers of both the old large bowl-shaped cannon and the new type of cannon, sealed them tightly with a plug, and then inserted a heavy stone.
In the four rounds of continuous firing, the new type of cannon showed no problems, but the bowl-shaped cannon developed a crack in the bottom corner of the powder chamber.
Upon checking the results, Choi Hae-san opened his document and wrote:
“Test results confirm that making the rear of the cannon and powder chamber curved strengthens its structure. It seems appropriate to upgrade other cannons or design new cannons in a similar shape.”
“…Therefore, this non-standardized sneak bomb not only serves as a missile, but everything down to the design of the cannon has passed through the hands of His Highness, the Crown Prince.”
At Choi Hae-san’s explanation, Sejong and his ministers once again looked towards the Crown Prince.
“This fellow… you’re making even saying ‘astonishing’ tiring now.”
At Sejong’s words, all the ministers nodded their heads. Having seen a series of amazing devices, the ministers were exhausted. No, the chief state councilors and the Assistant Secretaries of the Treasury were singing to the heavens, calculating the budget that would be required for mass production.
“I would like to see this newly-created cannon.”
“As you command.”
A moment later, two carts entered the demonstration area. Each cart was drawn by two horses.
“The first cart carries a cannon mounted on a gun carriage, and the second cart carries the non-standardized sneak bomb and gunpowder to be used for the cannon.”
“Hmm…”
Listening to Choi Hae-san’s explanation, Sejong scrutinized the carts. On the cart connected to the gun carriage, there were two wooden boxes.
“Those boxes contain the missiles and explosives that are to be used immediately after the cannon is dust-proofed.”
The soldiers opened the lids of the boxes that were loaded on the cart. Small bags caught the eyes of Sejong who had been examining the boxes.
“What are these bags?”
At Sejong’s question, Choi Hae-san opened a bag and pulled out its contents.
“They are a fuse (fire rope) which determines the time until detonation, a cotton wick to wrap the fuse, and a paper tube, which holds one ‘nyang’ of starting explosive used to ignite the main charge, and all of which are to be inserted into the non-standardized sneak bomb.”
At Choi Hae-san’s explanation, Sejong nodded his head. “I see. The main explosive doesn’t catch fire from the fuse, so we ignite it with the starting explosive. But, a paper tube?”
“At first, we used bamboo, but there were issues with uniformity so we decided to make tubes out of paper.”
“I see. That’s a good idea.”
“It was the wisdom of His Highness, the Crown Prince.”
When Choi Hae-san credited the Crown Prince, Sejong looked back at him.
“I can see your efforts.”
“It is the merit of General Choi, General Lee, and all the other military officers and craftsmen.”
Now, it was the Crown Prince crediting the soldiers and craftsmen in turn.
Sejong, who had been looking at the cannon, stopped his gaze at the back of the cannon. What caught Sejong’s interest was the part that was connected to the base of the cannon. There was a screw-engraved column standing there, and next to the gears that were connected here and there was a handle similar to a winch. Next to that, there was a half-circle dial with Chinese characters written on it – ‘long-range’, ‘short-range’, and ‘very short-range’.
“Crown Prince, what is this used for?”
“Yes, it is used to adjust the angle of the cannon to control the range.”
“Control the range?”
“Yes. It works like this.”
As the Crown Prince turned the winch-like handle, the muzzle of the cannon moved up and down. Watching this, Sejong turned his head.
“So you adjust the distance by adjusting the angle of the cannon muzzle?”
Choi Hae-san, who was next to him, answered Sejong’s question right away, “Yes, Your Majesty.”
“How so?”
“It’s the same principle as shooting a bow. When you want to hit a target far away with a bow, don’t you lift the bow and shoot it in a parabolic trajectory?”
“Aha!”
At Choi Hae-san’s explanation, Sejong nodded his head and let out a sigh of admiration. Choi Hae-san explained, pointing to the semi-circular distance gauge.
“According to this scale, if you adjust the angle of the muzzle, you can control the distance from 300 ‘bo’ to 500 ‘bo’.”
(Note: The “bo” here is a traditional Korean unit of length equivalent to about 3.03 meters or 9.94 feet.)
Sejong, who had been carefully examining the scale under the guidance of Choi Hae-san, looked back at Choi Hae-san and Lee Chun.
“You must have put a lot of effort into figuring out this scale.”
“Yes, Your Majesty.”
At Sejong’s words, Choi Haesan and Lee Chun nodded.
By a mix of intentional design and fortunate discovery, they had fired hundreds of rounds of sneak bombs to accurately measure a fact they had stumbled upon.
Filled with soil and pebbles to reduce the unnecessary consumption of gunpowder, the firings of these sneak bombs did not rest, continually flying through the air. Eventually, they had to make nearly a hundred new sneak bombs to replace those broken from metal damage. But that was not all.
A considerable number of cows raised in the nearby farms of Area 51 had died from the stress caused by the explosive noise, requiring a significant sum for compensation. The meat from these slaughtered cows ended up on the tables of the craftsmen and soldiers.
“If we can adjust the distance like this, it would be more effective in battle. Can this be applied to other artillery?”
At Sejong’s question, Hyang replied, “The scholars at the research institute are currently studying it.”
“But?”
Having heard the response, Sejong sought out Jeong Jo among the officials.
“Vice Director Jeong, your faith in science is immeasurable.”
At Sejong’s words, Jeong Jo bowed his head and replied, “I am honored by your words, Your Majesty.”
Jeong Jo’s voice was filled with emotion.
‘I can’t even go home right now…’
Thanks to the same order issued by Hyang, the scholars at the research institute were clenching books that recorded the results of the artillery fire, fighting a ‘war with numbers’.
They were investigating the changing range in all sorts of diverse and bizarre situations, creating charts, formulating them, and making range adjustment plates for each type of artillery under Hyang’s order.
Due to this, the scholars at the research institute could only go home on their designated days off – 9 days of work and 1 day of rest. It was only thanks to Hyang strictly adhering to this rule.
However, there were times when the scholars voluntarily worked overtime. That period was when they were fermenting ‘meju'2.
Joseon was a ‘soybean paste country’, consuming a lot of doenjang (soybean paste) and soy sauce. As consumption was high, every house was filled with jars of paste, and the neighborhoods of Hanyang were filled with the smell of doenjang. Thus, the people of Joseon were familiar with the smell of soybean paste. However, even for them, the smell of fermenting meju was a hardship.
Especially, the houses with many family members inevitably had to ferment a large amount of meju. Therefore, the homes of high-ranking officials with many servants and guests suffered more from the stench of meju.
The palace also fermented a large amount of meju, but because the palace had a vast space, the smell of meju was not so severe. For this reason, officials tended to delay their return home as much as possible during the meju fermenting period.
In any case, due to the orders of Sejong and Hyang, Joseon became the first country in the world to create and implement a shooting range chart 3 for artillery.
Having inspected the artillery firing sneak bombs and the associated equipment, Sejong straightened his waist.
“Hmm, it seems we’ve seen everything. But before we check the accounts, there’s one last thing to confirm. The armor worn by the soldiers and officers here is different from what I’ve seen before, explain this to me.”
“We have prepared for that. Let me guide you.”
- Regent and father of King Gojong (a.k.a Last King of Korean dynasty)[↩]
- Brick of dried fermented soybeans[↩]
- “A specialized tool designed for specific firing devices such as guns, cannons, rocket launchers, etc., including the corresponding types of ammunition and their propellant numbers. It is a handbook that contains the corresponding relationships between firing angles, ranges, and other ballistic parameters. It serves as the basis for accurate and effective shooting, the production of aiming devices, and can also be used as fundamental ballistic data for design and command instruments.”[↩]
2 more chapters before we end this arc!