January 30, Continental Calendar 3900—the era in which Jin's duplicate lived.
According to the calendar of Planet Ars, it was the final day of January.
The sky above Onogoro Island, floating in the seas of the Southern Hemisphere, was filled with flying objects of every imaginable shape and size.
"Oh! This turned out perfectly!"
"Hmm, the stability is still a little off... Maybe I should increase the dihedral angle of the main wing by another degree."
"It’s decent enough. Now, if I could just boost the speed by another ten percent..."
The mutterings of the pilots drifted through the air as they tested their craft.
"Wow, everyone is really doing impressive work."
Jin Nidou, the Magi Craft Meister, looked up at the sky with genuine admiration.
The residents of Onogoro Island revered him as their "Ancestor," a title he found quite awkward. Eventually, they had reached a compromise, settling on calling him "Jin-sama."
Tomorrow was the day of the Model Aircraft Competition.
Because of this, the participants were all busy making final adjustments to their machines. Since they were all essentially part of one large family, Jin—the organizer—was pleased to see that they were free from the typical political maneuvering and secrecy that might usually plague such a contest.
The final regulations for the competition were as follows:
- Size: The aircraft must fit within a 1.5-meter cube.
- Weight: No limit.
- Material: Must be constructed using materials available on Onogoro Island.
- Propulsion: Must utilize a rotating engine and generate thrust via a screw propeller. The number of engines is unrestricted.
- Lift: Lift must be generated by wings. Any direct lift provided by propellers (such as vertical take-off designs) will result in disqualification.
- Airframe Shape: No limit.
- Control: Pilots must use the cockpit-style control seat designated by Jin.
- Special Requirement: The supplementary control mechanism provided by Jin must be installed and used.
Since this was the inaugural event, Jin suspected there might be some oversights in the rules. He planned to add or clarify regulations as necessary during the competition.
During the conceptual phase, he had considered a 1-meter cube limit. However, he eventually settled on 1.5 meters, reasoning that smaller craft would be less stable and harder for spectators to see from the ground. He had briefly considered 2 meters, but decided against it because it would have far exceeded Rubina's height of 123 centimeters.
The requirement to use his designated cockpit-style control seat was a lesson learned from a previous automobile race; it was intended to minimize the advantage gained through superior control interfaces. Furthermore, the mandatory supplementary control mechanism was designed to handle tedious attitude corrections, allowing the pilots to focus on flying exactly as they intended.
The competition segments were organized as follows:
- Speed (High): A race around two designated poles; the shortest time wins. Points: 100 for 1st, 80 for 2nd, 60 for 3rd, 40 for 4th, 20 for 5th.
- Speed (Low): A race around two designated poles; the longest time in the air wins. Points: 100 for 1st, 80 for 2nd, 60 for 3rd, 40 for 4th, 20 for 5th. Note: Any contact with the ground results in immediate disqualification.
- Pattern (Aerobatics): Precision flight through a designated pattern. Scored by Testa, the island's management magi-brain, out of 100 points.
- Free (Aerobatics): A freestyle flight where performance and creativity are evaluated. Scored by the entire audience. Each spectator's vote is weighted (100 divided by the number of spectators).
- Race: A high-speed race through a course marked by ring-shaped gates. Missing a gate results in disqualification unless the pilot circles back to pass through it correctly. Points: 100 for 1st, 80 for 2nd, 60 for 3rd, 40 for 4th, 20 for 5th.
As a bonus category: 6. Design: The audience scores the craft based on appearance, gimmicks, and overall performance. Scored out of 100 points.
Onogoro Island was protected by a barrier. By fine-tuning its strength and properties, the interior could be shielded from external wind and rain. Consequently, the competition would be held in perfectly windless conditions, allowing participants to focus on their technique without worrying about sudden gusts.
Naturally, Jin was also participating as a guest. To be honest, he had been dying to join in.
The aircraft Jin had built featured variable-sweep wings. The main wing used a three-layer structure. At low speeds, the three layers would slide apart to increase the wing area, reducing wing loading and providing more lift. At high speeds, the layers would overlap and sweep backward, streamlining the craft for maximum velocity.
For propulsion, he used a pseudo-jet engine built around a ducted fan. A ducted fan consists of an engine and a propeller mounted inside a cylindrical duct or nacelle. Because the fan diameter is smaller, it necessarily rotates at high speeds, which makes it perhaps even more suited for models than for full-sized aircraft (as efficiency typically drops when propeller tips exceed the speed of sound).
Depending on the design, this setup also allowed the engine—which is usually heavy—to be placed near the aircraft's center of gravity, significantly increasing maneuverability. However, it did come with disadvantages, such as increased drag at high speeds and higher complexity.
Jin’s primary reason for choosing it was speed. Much like a jet engine, narrowing the exhaust nozzle increases the jet velocity, which translates directly to higher airspeed. While traditional propeller propulsion is limited by the speed of the air the propeller can move, a ducted fan can exceed that limit. Jin had decided to prioritize this one advantage, either ignoring the drawbacks or solving them through technical ingenuity.
To be fair, this was based partly on a misunderstanding of Jin's. The thrust of a propeller comes from the lift generated by the blades themselves, not merely the "wind" they create; the wind is simply a result of that lift. Furthermore, a ducted fan is technically less efficient at very high speeds... but Jin's sheer crafting skill was so great that he hadn't even noticed the theoretical limitations.
"Oh, this feels excellent."
Sitting in the cockpit-style control seat, Jin was enjoying a view as vivid as that of a real pilot. A magi-screen stood before him, displaying a real-time feed from the aircraft and providing an immersive sense of flight.
For this event, pilots could also switch to a bird's-eye view provided by observation magic eyes installed high above. He was spending the day before the race performing free flights just to calibrate his senses to the interface.
"Jin-sama's machine really is incredible."
In the control seat two spots to his right, Rubina was conducting final checks—or rather, getting in some practice laps.
Her craft featured triangular wings, a "delta-wing" design. It was a machine that achieved a high balance between stability and speed. While the shape was ideally suited for high velocity, it was surprisingly capable at low speeds as well.
At low speeds, a delta wing requires a high angle of attack—tilting the nose up sharply relative to the flight path—but it can maintain lift at angles that would cause a traditional tapered wing to stall. The fact that origami airplanes can fly so slowly is likely due to this same principle, though their light weight is certainly the primary factor.
Rubina's delta-wing plane flew with extreme agility, performing "rolls" and spiraling maneuvers with ease.
"Ugh... my head is spinning after all... I think I'm going to be sick... Healing!"
Rubina was insistent on piloting from a first-person perspective, so she was trying to build up her resistance to motion sickness. Whenever she felt the nausea rising, she would cast Healing on herself and keep practicing.
"Yes, this is coming along nicely."
Natalia was flying a triplane. Its design was reminiscent of a Fokker Dr.I from the First World War. Her goal was to maximize lift at low speeds and achieve superior turning performance. She had compensated for the increased weight and drag of the three wings by installing a high-output propulsion system.
She was currently testing its low-speed stability, and the craft was performing remarkably well.
The other participants had also completed their testing and practice, and everyone was brimming with fighting spirit for the main race the following day.
With all preparations for the venue complete, Onogoro Island slowly sank into the quiet of the evening.