Black Corporation: Joseon

Chapter 387

Chapter 387

The next morning.

A new notice was posted on the bulletin board.

“Another Challenge Record entry? They’ve been frequent lately.”

“What is it? What is it?”

“Hey, move your head out of the way!”

Researchers and craftsmen gathered in droves to read the contents of the new notice posted on the bulletin board.

The first thing the researchers and craftsmen checked was the grade of the entry. Checking the grade first had become a habit for everyone since the Challenge Record was established.

And the eyes of those who confirmed the grade all widened.

“Huh?”

“What kind of grade...”

The newly posted notice had two grades applied simultaneously.

Grade: Lone Army’s Struggle – Lower, Moving Mountains – Upper.

It was a simultaneous assignment of two extreme grades.

Surprised by this unexpected grade assignment, people examined the content more closely.

New Challenge Record Entry Notice.

Date: 17th day of the 3rd month, Year of Gyechuk (1433).

Proposer: Jang Yeong-sil

Content: Create a propulsion device for ships by applying the shape of a windmill.

Grade: Lone Army’s Struggle – Lower, Moving Mountains – Upper

“Ah!”

“Oh no!”

“To think we didn’t come up with this, what fools we are!”

The researchers and craftsmen of the team tasked with developing the propulsion device read the content and blamed themselves, slapping their foreheads.

Windmills were not unfamiliar to Joseon people. It was one of the toys that every boy had played with.

Called “pallanggaebi,” “doreurami,” or “hoehoi-a” depending on the region, windmills were toys that had been passed down since before Joseon. Initially, they had a strong magical character – typically attached to rice sheaves with five grains on the first full moon – wishing for a good harvest, but later became children’s toys.

They blamed themselves for looking for answers in strange places despite having such an object that accompanied their childhood.

After this period of self-reproach, the researchers and craftsmen all had the same question.

“But why did it receive two extreme grades simultaneously?”

Unable to come up with a suitable answer no matter how much they thought about it, the researchers discussed with their colleagues.

“Do you know why it received such grades?”

“I’m not sure. Do you have any idea?”

“Should we ask His Highness?”

When one researcher mentioned Hyang, other researchers simultaneously replied.

“Would he answer?”

***

To the researchers and craftsmen of the research institute, Hyang was a ‘good but demanding boss’.

When they failed in their assigned tasks or missed deadlines, Hyang carefully examined the reasons. If it wasn’t due to the negligence or carelessness of those in charge, and if there were no human casualties, Hyang rarely punished them.

Instead, what Hyang wanted from those in charge was a clear lesson learned.

While Hyang seemed like a good boss in this regard, he was demanding in other areas.

There were two areas where Hyang was particularly fussy.

One was the budget, and the other was immediately asking questions about assigned tasks without even trying to figure things out.

‘Pondering why such a grade was assigned is the first step towards success.’

Because Hyang had said this, researchers had to rack their brains from the very beginning on the question of ‘why this grade?’

“His Highness always wants us to do our best.”

In one corner of the Development Department’s laboratory was a spring mechanism made by Jang Yeong-sil. The researchers investigated the performance by attaching screw propellers to the shaft connected to the spring mechanism.

Wiiing!

As the screw propeller connected to the spring mechanism began to rotate at high speed, the power shaft started to vibrate slightly up and down.

“Huh? Why is the shaft shaking? Hey, everyone!”

A sharp-eyed researcher noticed the anomaly and called his colleagues.

The colleagues also confirmed the vibration, but here the researchers made a fatal mistake.

“Isn’t it vibration caused by the spring unwinding? We had something similar with the water wheel before, remember?”

“Is that so?”

“Let’s quickly attach it to a ship and experiment.”

And so, a model ship equipped with the 8-blade screw propeller that had shown the best efficiency was floated in the water tank.

“Start!”

As the experiment using the model ship began, the researchers’ faces turned pale.

“Why is the ship doing that!”

The ship began to shake back and forth, unable to move straight, and started moving diagonally while tilting to one side.

“Stop! Stop!”

The researchers urgently stopped the experiment and thoroughly examined the ship to find the cause, but they couldn’t easily find the reason.

“We have no choice. Let’s stop here for now and write up a report to submit.”

***

Hyang, upon receiving the report, had to forcibly restrain himself from speaking.

‘The ship’s crooked movement is clearly due to torque, and the vibration problem... Could it be because they made an even number of blades? As far as I know, ship propellers always had an odd number of blades, right?’

In fact, large ships use two screw propellers to prevent the ship from deviating from its straight course due to the reactive torque pair (Heeling torque/moment) acting between the ship and the propeller.

And ship propellers are made with an odd number of blades. The reason is that with an even number, resonance frequencies occur as many times as the number of factors, but with an odd number, only one resonance frequency occurs, creating various problems including vibration.

‘That’s why even in the 21st century, all sorts of cutting-edge technology was mobilized just to make that seemingly simple screw propeller, and in extreme cases, Japan even took a hit, right?’

During the Cold War era, Japan’s Toshiba violated COCOM (Coordinating Committee for Multilateral Export Controls) contracts and exported ultra-precision large machine tools to the Soviet Union. As a result, NATO countries, including the United States, began to have trouble tracking Soviet submarines.

Upon discovering that Toshiba was the culprit, the United States immediately imposed an export ban on Toshiba, and from this point, the decline of Japanese electronic products and semiconductors began.

This happened long before Hyang was born, but Hyang remembered it because when Japan excluded Korea from its whitelist and imposed trade sanctions, the internet mentioned this incident, saying, “The Japanese make even bigger mistakes!”

Therefore, Hyang had to forcibly restrain his itching mouth.

‘This is something they need to ingrain in their bodies through trial and error! Only then will they be able to use it better in the future!’

Issues like torque and resonance were applicable in various fields, so it was essential to understand them before moving on.

***

While they were pondering over this intractable problem, another variable tripped up the developers.

This time, it was the issue of the material used to make the screw propeller.

In the course of repeated experiments, the wooden screw propellers broke faster than expected.

“Wood won’t do! Let’s try other materials!”

And so, screw propellers were made of iron and copper.

Due to manufacturing technology issues, the prototypes made were quite large, and as a result, Jang Yeong-sil had to make a model ship 1/10 the size of an actual ship.

The model ship, made larger and even equipped with a small steam engine, was experimented with on the Han River, and similarly failed.

In addition to the basic problems of vibration and deviation, this time the blades of the screw propeller were also deformed.

Finally, the researchers could understand why this task was graded “Moving Mountains – Upper”.

***

While the researchers were struggling like this, Jang Yeong-sil again sought out Hyang.

“Your Highness, I have an idea.”

“Let’s hear it right away!”