With Elsa’s ‘leveling up,’ Jin’s burden was lightened significantly.
“Jin-nii, I’m finished.”
“Oh, let’s see.”
Elsa had been crafting what was known as a ‘Golem’s eye’—essentially, a light sensor.
“Now I just need to Write In the magi-formula,” Jin said.
While Elsa had worked on the sensor, Jin had been devising the magi-sequence—the magical control flow—required to use it for temperature measurement.
“‘Write In’... and there. That should do it.”
“Father, is this casing acceptable?” Reiko asked, presenting her work.
“Let’s have a look.”
Jin had tasked Reiko with manufacturing the housing to hold the components.
“Yeah, it’s a perfect fit. I’ll just slot it in like this...”
The device Jin had completed was, in essence, a ‘temperature comparator.’
It was roughly the size of a television remote. Instead of an infrared LED at the tip, it featured the Golem’s eye that Elsa had crafted.
By pointing this light sensor at a ceiling or wall, the user could first record a reference temperature in the form of infrared radiation. When measuring the infrared radiation of the same spot later, a small magi-stone on the device would glow red if the temperature was higher and blue if it was lower.
The measurement had to be taken from the same spot because the wavelength of the emitted infrared radiation varied depending on the color and material of the object.
Jin first pointed the device at the ceiling and pressed the button to store the reference. This recorded the wavelength of the infrared radiation currently being emitted by the ceiling.
“‘Heat.’”
Next, he used Craft Magic to warm a patch of the ceiling and pointed the temperature comparator at it once more. A red light flickered to life.
“Good, it’s a success.”
Applying this principle would make extremely precise temperature control possible. At that point, Elsa spoke up with a question.
“Jin-nii, when we visited the Keuwan Ruins, I noticed the interior was climate-controlled. How did they detect the temperature back then?”
“Ah, I see.”
Since Elsa wasn’t as intimately familiar with ancient technology as Jin, it was a natural question for her to ask.
“They didn’t actually detect the temperature,” Jin explained.
“Then how did they do it?”
Jin thought for a moment about how best to explain the concept.
“Well, you know that fire-attribute magic can manipulate thermal energy, right?”
“Mm.”
“Basically, they determined the exact amount of heat needed to maintain a comfortable room temperature through trial and error. Then, they simply filled a fixed volume of air—the space within the room—with that specific amount of heat constantly.”
“...That sounds surprisingly sophisticated, in a way.”
Jin nodded. “Yeah, it is. Controlling the amount of heat within a designated space is quite advanced. However, it’s inconvenient and lacks flexibility.”
“Mm, I see. You can’t change the temperature easily, and if the dimensions of the room change, you have to recalibrate the whole system.”
“Exactly.”
To put it another way, it was a control method that kept the energy of the air molecules in the room constant. Such a method required a reset if the room size changed and was entirely unsuitable for controlling the internal temperature of a form-fitting spacesuit.
“I understand now why it’s inefficient,” Elsa said.
“Right?”
Through several exchanges like this, the prototype for the temperature control device was completed by that evening.
They eventually decided on Ancient Dragon hide for the spacesuit material.
According to the results of Laojun’s tests in space, the hide had successfully endured the vacuum, intense heat, and extreme cold. Ground Spider resin (GSP) had yielded similar results, but Ancient Dragon hide ultimately won out due to its superior physical strength.
『However, we will use Ground Spider resin (GSP) for the transparent sections, such as the helmet visor,』 Laojun reported.
In terms of transparency, Ground Spider resin (GSP) was far superior.
“Jin-nii, is it correct that while the material is white as silk thread, it becomes transparent as a resin because of the way light reflects and scatters?”
“Yeah, that’s right.”
If you crush glass into a powder, it turns white because light undergoes diffuse reflection on the irregular surfaces. Jin understood that the thin silk of the ground spider acted the same way. However, when melted together into a resin, its inherent transparency manifested clearly.
“Next is the material for the outer hull, I suppose.”
Currently, they were using 18-12 stainless steel-type materials, but Jin was worried about distortion caused by thermal expansion in a vessel of that size.
“Invar would be best.”
He recalled the dome of House Tierra he had seen in the nation of New El. That had been made from an alloy of iron and nickel called Invar.
“But the strength is an issue...”
He was concerned about whether standard Invar had the structural integrity required for a large-scale spaceship.
“Maybe I should just develop a new alloy...”
First, he considered ways to reinforce Invar.
“The standard approach would be adding mithril.”
Reinforcement through magic was common on Hourai Island, with magi-adamantite being the most prominent example.
Experiments began the following morning. He started by adding one percent mithril. Because he was experimenting using Craft Magic, the efficiency was on another level, and he found the optimal solution by midday.
The final composition was 62 percent iron, 32 percent nickel, 1.5 percent mithril, 4 percent cobalt, and 0.5 percent manganese. It was non-magnetic, and its specific gravity was 8.24, slightly higher than ordinary steel. By applying magical Reinforce, its strength increased to over ten times its original value.
“Alright, let’s call it ‘Magi-Invar.’”
It was a typical Jin-style name—simple, but it made the nature of the alloy immediately clear. Since both iron and nickel were produced in large quantities on Hourai Island, it was a practical choice as well.
『My Lord, in that case, I would like to proceed with the construction of the flagship in parallel with the various tests of the prototype spaceship.』
Jin nodded at Laojun’s suggestion. “Yeah, that’s fine. As long as there aren’t any major design changes, we can make adjustments anytime.”
That was the beauty of Craft Magic. As long as the overall size and shape remained constant, altering the internal structure was a simple task.
『Very well. I shall begin construction of a 500-meter class vessel.』
“Ho-hold on a second. Why does it need to be that big?”
『Yes, My Lord. If you are to be on board, I cannot guarantee your safety unless the vessel is at least that size.』
Laojun then launched into a lengthy, exhaustive explanation of his plan for maximizing safety.
“...But still...”
Even Jin felt that a diameter of 500 meters was excessive.
“...So, if we do it like this instead...”
Laojun refused to budge easily, and the negotiations proved difficult.
“...I’m wiped.”
“Good work, Jin-nii.”
Elsa had been listening nearby. Although she wanted to offer her opinion, she didn't feel she understood enough about spaceships to intervene.
“But I understand Laojun’s point. It’s better to minimize risks. I don’t think there’s any need to be stingy with materials for something like this.”
Elsa believed that for a ship venturing into the unknown reaches of space, holding back would be a mistake.
“...I suppose so...”
In the end, the size of the flagship was settled at 300 meters in diameter.