Hourai Island sat in the middle of the ocean, far to the east of the Lauren Continent where much of humanity lived.
With the Tropic of Cancer passing directly overhead, its climate was nearly subtropical. This was the true base of operations for Jin Nidou—the Magi Craft Meister and the Lord of Kunlun.
Currently, Jin was preoccupied with a significant hurdle: travel time. He needed a way to bridge the 1,300-kilometer gap between Kunlun Island and Loizart, the capital of the Shouro Empire.
"Basically, I need to hit 200 kilometers per hour," he mused.
Jin calculated that if he could travel at that speed, he could reach the capital in six and a half hours. That would put any known location in the world within a single day's journey.
"But with my current airship, that’s pushing it a bit..."
Even with a wind-blocking barrier and a force generator, 150 kilometers per hour was the limit. Any faster and he worried about the structural integrity of the craft, especially if it hit an emergency situation like a sudden gust of wind.
"I’ll just have to rebuild it from scratch."
Once Jin made a decision, he acted quickly. He had Reiko prepare the materials while he asked Laojun to dispatch Daidara and the Smith units to assist.
At the moment, Elsa was away, visiting her family home in the Shouro Empire. This meant the project would take place in the large, dedicated workshop Jin had constructed behind the laboratory.
"I’ll keep the length at forty meters."
It was the same size as his current ship, matching the scale of the large vessels used by the Shouro Empire and other nations.
"This time, it’ll be a rigid airship."
Unlike a non-rigid airship, which relies on internal gas pressure to maintain its shape, a rigid airship uses a structural frame—usually metal—covered by an outer skin, with multiple individual gas bags housed inside.
While there were trade-offs to the design, Jin chose this method to maximize the craft's structural rigidity. He designed it in an elongated teardrop shape with stabilizer fins at the rear. On the outside, it wouldn't look much different from the airships one might see in modern Japan.
The interior, however, was something else entirely.
"The frame will be 64 light silver."
He would make it as light and sturdy as possible. Naturally, the outer skin and the internal gas bags would be crafted from Ground Spider resin, or GSP.
Instead of a suspended gondola, he decided to attach the passenger cabin directly to the frame. This would slightly obstruct the view directly above, but it would significantly reduce swaying.
"I’ll design it to accommodate thirty people."
In truth, gas bags of this size couldn't lift thirty people by buoyancy alone; the design would normally only support about four. However, Jin had a specific purpose in mind that required a thirty-person capacity.
He would compensate for the weight using force generators.
"Father, wouldn't gravity control magic be more effective?" Reiko asked.
"Yeah, that would work too. But I still don't quite have a firm grasp on how gravity control magic actually functions..."
"What do you mean?"
Jin paused his work to explain. "While it’s called 'gravity,' it seems to alter mass as well. Plus, even when you increase gravity locally, it doesn’t trigger a downburst."
By "downburst," Jin was referring to an intense downward air current. If the magic were simply a physical force, a localized increase in gravity should have caused a significant atmospheric reaction.
One could simply shrug and say "it’s magic," but since most common spells functioned as extensions of physical laws, the discrepancy bothered him.
"And then there's the efficiency factor," Jin added. "A force generator consumes less free ether than gravity control magic. That alone is reason enough."
"I see. I understand," Reiko said, appearing satisfied.
Jin moved on to assembling the Magi Machine.
"Father, what is that?"
"A gyro."
"A gyro?"
The "gyro" Jin referred to was a high-speed rotating disk. He was picturing the gyroscopic spinning tops he had played with back on Earth. More accurately, what he was building was a gyro stabilizer.
Inside a sealed housing, a disk made of adamantite would be spun at high speeds using wind magic. It operated on the same principle as a turbine, but since it didn't need to output mechanical power, it consumed very little free ether.
By installing this, he could suppress the ship's swaying. Since a single disk wouldn't suppress movement around its own axis of rotation, he solved the issue by using two disks spinning at right angles to each other, creating a unified gyro stabilizer unit.
"For propulsion, I’ll go with Jet Thrusters."
To ensure efficiency didn't drop during rain, he decided to use Jet Thrusters instead of standard Wind Thrusters.
"Father, is the cabin layout acceptable?" Reiko asked. She had been tasked with crafting the interior.
"Yeah, looks perfect."
For the interior, he hadn't used 64 light silver—which was essentially titanium—but rather an aluminum alloy. Specifically, he used super duralumin, which was aluminum alloyed with copper and magnesium. Though it lacked high corrosion resistance, it was more than suitable for indoor use.
Since it was significantly lighter than light silver—aluminum has a specific gravity of 2.7 compared to light silver's 4.5—it was ideal for interior components that didn't require extreme structural strength.
The cabin featured twenty folding chairs and ten built-in seats. He had given both types the same high-quality texture; despite being foldable, they didn't look cheap or flimsy. The backrests could be reclined until they were completely flat, allowing them to serve as beds.
The cabin also included a lightweight refrigerator and a Magi Range—essentially a microwave—allowing for light meals during flight. At the back of a small storage area was a Warp Gate, which allowed them to retrieve items from the base that hadn't been loaded onto the ship.
The interior of the gondola was completely airtight and climate-controlled, ensuring a comfortable journey. Additionally, a separate Warp Gate was installed as a dedicated emergency exit.
"You’ve done a great job. Thank you, Reiko."
Beaming at the praise, Reiko offered more help. "Father, what shall I do next?"
"The ship is about ninety percent finished. I’d like you to handle the test flight."
"Understood."
Testing was always Reiko’s responsibility. She tended to feel neglected if he asked any other golem to perform the task.
'Father, it’s performing beautifully. The swaying is being suppressed quite well,' Reiko reported via manacam from high above. 'However, I feel that reaching 200 kilometers per hour might be difficult.'
"Yeah, that will have to wait until the final outfitting is done. For now, just focus on the handling and balance."
'Understood.'
Reiko flew around the skies of Hourai Island for a while before eventually descending. Using the force generators, she landed the craft exactly where it had started with pinpoint precision. After disembarking, she provided a detailed report.
"Father, overall, the performance is excellent. The stability is far better than before, and I believe the speed can be pushed higher. The comfort levels have also improved."
"Good to hear. Now, what are the drawbacks?"
"Yes. Because we prioritized stability, the maneuverability has decreased slightly. Also, as I suspected, having no visibility directly overhead is a bit of an issue..."
Jin realized his mistake. By using the gyro stabilizer to ensure a smooth ride, the ship's response to intentional changes in orientation, such as turning, had become sluggish.
"Ah, right... that’s a problem," Jin muttered, falling into thought. While the gyro stabilizer reduced unwanted swaying, it acted as resistance when they actually wanted to change the airship's direction.
"Wait a minute... I just need to decouple it when we're turning!"
Jin’s idea was to mount the gyro stabilizer on a three-axis gimbal and lock or release those axes as needed. The three axes were the X-axis (pitch), Y-axis (roll), and Z-axis (yaw).
Swaying was simply rotational movement around these axes. Turning, likewise, was a rotation around one or more of them. Generally, "pitching" refers to the nose moving up and down, "rolling" refers to the ship tilting left or right, and "yawing" refers to the nose turning left or right.
Since turning required movement on these axes, a ship that resisted swaying also resisted turning.
"I’ll move the gyro stabilizer closer to the center of gravity and link it to the rudder so it automatically releases the fixed axis when we turn."
For example, when they wanted to turn left or right, the lock on the vertical Z-axis would be released, allowing for easier yawing. Achieving this with purely mechanical parts would be incredibly complex and expensive, but with magi craft, it required very little effort. It was almost like updating the firmware on a microcomputer.
"If we deploy a wind-blocking barrier to cut through the drag, I’m sure we can hit 200 kilometers per hour."
Reiko considered this for a moment. "I agree. With that level of stability, it should be possible."
"And for the overhead view, I'll install a 'Sky-scope'."
Like a submarine's periscope, he would install an optical device that allowed the pilot to see directly above the gas bags.
"I’ll also set it up so Laojun can operate it remotely, just in case."
It would serve as an autopilot.
"Finally, I’ll install the transporter gifted by No. 700672. I'll set the destination marker to Hourai Island."
With that, they could return to the island instantly in an emergency.
Thus, Jin’s second airship—the Konron 2—was completed.
Coincidentally, Elsa arrived back from her family home at the exact same time. Upon seeing the sleek new airship, her eyes went wide with surprise.