Lurona city [southern shores of Fuminao Legacy Kingdom], local time [1793.12.22]

“Bird wings?” Zeph asked, blinking in surprise. He turned around, looking critically at the metal plates making out the shape of the wings. Despite the fact that he had hunted birds of all kinds for months on the summit of one of the mountains in the Torrent range, he never noticed how close their design has come to the biological equivalent.

“Yes. I believe we already saw similar concepts before,” she said with a slight disappointment in her voice. “As much as I would like to see a machine imitating nature, all of them were failures.”

They all moved closer to take a better look at the prototype. It was hanging from a rigid cubic framework, hold in the air by two rods connected directly to its internal structure, piercing the top of the body at the front and back. Its overall shape was identical to a standard Earth’s plane, but its surface was ‘puffy’ because of the metal plates sticking out in most places.

Zeph had to agree with Raennte – the plates making up the casing looked a lot like feathers, if one ignored their relative size. Until now, he had thought of them as scales, but after allowing his imagination to run a little wild, the concept fitted much better.

Sleep deprivation seems to strengthen the fixation of the mind, he noted mentally. I should have been able to notice the similarity sooner, knowing my experiences and work practices. Willpower is probably acting up… which isn’t that surprising, taking into account I use its derivate to keep my mind stable…

The prototype had only a one-meter wingspan, but the plates were at least 5 centimeters wide. Their length depended on the curvature of the surface they tried to emulate, but never going below 2 centimeters. Of course, the front-facing ones were curved themselves – without drastically decreasing their size, it would be impossible to emulate the small radius of the curves. But because they were so wide, Ghrughah would be able to directly modulate their shape on the fly. The leading edge’s shape was the most important part of the wing’s shape, so they had to depend on the Blacksmith’s proficiency in material manipulation to obtain sufficient accuracy. The plates on the back of the wings, though, were flat and formed a wavy edge, thus creating an illusion of feathered appendages.

Arennte poked the silver model a few times while eyeing it from different angles. “It’s definitely different from the biomimetic wings we saw until now,” he commented with raising excitement. “The lack of joints aside, the intersection’s shape and the material flexibility are all wrong.” He looked up at his sister. “If I am not mistaken, they aren’t even trying to emulate the natural wings.”

“Hou? Now I am curious.” She placed a finger on her cheek and bent down to assess the plates. “But assuming it would fly, did you manage to get around the problem of turbulences?”

“Everything in due time,” Zeph answered curtly. “The presentation will start soon. But before that, I would like to hear more about those biomimetic models you were speaking about… What made them a failure?”

It was his turn to become excited. Making a mechanical wing model wasn’t something that saw much success on Earth, but the pilots sounded like the idea wasn’t just plain stupid here, on Corora.

“Well…” Arennte stood up from his crouching position and turned to him. “I could speak about it for hours and not even scrape the surface of the issue. But it all goes down to one basic problem – the birds are influencing the properties of air around their wings, and the process is so convoluted that it was deemed impossible to imitate.”

“To be more exact,” Raennte interjected, her gaze focused this time, “to counteract strong fluctuations of Air Magicules, Mana upward currents, and other Mana-related effects influencing the properties of the air at low altitudes, most of the avians developed unique means to keep themselves stable when flying. I say most, because bigger species have no use for those methods.”

Zeph thought about it for a moment, then nodded. “I can understand that part. Mana and Magicules are constantly altering the air density, for one. But how are the birds able to do that? I know for the fact, that smaller species don’t use Skills to fly.” His time with ‘Corora lifeforms’ paid some dividends in the end.

“No, this has nothing to do with the System Onji,” Raennte shook her head, then crossed her arms inattentively. “They weren’t even present in our world a few thousand years ago. It’s a result of natural adaptation…” her voice petered out as she lost focus and started to think about something deeply.

“Which is why the problem is beyond even our best scholars,” Arennte finished for her, filling up the sudden silence. After making sure his sister was still in her own world, he decided to continue the explanation. “The aerocrafts using biomimetic wings instead of a wing—and don’t ask me why the canopy of a ship is called that, it’s simply stupid and I never found the etymology of the word—tend to flip over as soon as Mana currents on one side fall below a certain threshold. Or the air thins too much, but that’s a rare case,” he started rambling passionately, if not very comprehensibly. “No amount of enchanting can counter that, as the wings’ weight and length are just too much to recompensate for. Especially in models trying to emulate the movements of real wings – in case of not finding enough resistance while moving downwards, the inertia immediately destabilizes the whole aerocraft. On the other hand, the theoretical size of a stable flying vehicle of this kind, one able to ignore minor Mana fluctuations, is an impossibility. The materials available on our stratum won’t be able to withstand the burden. Worse yet, known enchantment systems wouldn’t be able to output enough stabilizing Magicules to counter that, not even mentioning the power necessary for Mana constructs of such a size… Umm…” He paused after seeing their confused faces and tilted his head innocently. “Should I elaborate on some parts?”

“No, no,” the Blacksmith immediately shook his head. “We can talk about it all we want after we are done here. Right, Zeph?” He looked at him with pleading eyes. Zeph could sympathize. After the guy’s short lecture, he had more questions than answers.

Zeph just opened his mouth to confirm when Raennte suddenly exclaimed, snapping her fingers. “I remember now!” She looked down at Zeph with a goofy smile. “The main reason the ingeniators are unable to imitate the avians’ methods of flight! Ummm,” she lost focus for a moment there but quickly recovered. “The feathers, you know, are a great medium for channeling Mana. And I am not talking about the Organic Magicules, that conglomeration can be channeled through any part of the body, really…”

She took a deep breath, trying to not yawn but covering her mouth nonetheless. “Excuse me, I’m a little tired lately… Where was I?”

To his surprise, she used a different term for Mana-L. P’pfel called it life energy, but was mostly ignorant of its properties, even if he himself was able to use the Stabilizing Spell.

The discrepancy in naming suggests there is more to it. She called it like any other Magicule, but P’pfel’s term suggested it was also used in a different context…

After massaging her eyes for a second, Raennte started to speak again. “Ah, yes... The feathers. Umm, so, like, the main reason for the confusion is the inability to determine how the animals are channeling their Mana through them. Or rather, in what patterns. It’s almost certain they are using simple Mana constructs. The situation is even more complicated because different patterns are inherently present in the feathers of every individual.”

That’s why the feathers are worth so much! Zeph realized with a start. Unique, natural Spell construct patterns! Shit… selling the feathers was a mistake! I should have known better, seeing the price!

“Weeeelll, that’s not all, of course,” she said with a lazy shrug, rolling her eyes in irritation. “The designers are always forgetting about the pili muscles of the feathers, for example. Or the…”

Zeph frowned. Huh? That definitely didn’t translate right… I am quite sure birds don’t have those. A mesh of smooth muscle and ligaments, was it? Or are avians here just that much different anatomically? Eh, whatever. He refocused on what Raennte was saying. Thankfully, he didn’t lose much.

“…or about flexibility reactions… Not the Enhancement,” she wagged her finger ‘threateningly’ in Zeph’s direction. “I am talking about their anatomy. The feathers are connected, they are influencing the movement of their neighbors and flex naturally under pressure. Those are all the most basic mechanisms, but of course, no one ever listens to Biologists!” she complained with a grimace. “A good model is a simple model, they say. And then, they all fall down.” She shook her head disapprovingly.

“In their defense,” her brother spoke, glancing at her, “this saying is not baseless. The more complicated construct, the more room for malfunction and accidents. And some people did try to emulate those natural mechanisms, but it’s simply impossible to implement all of them at once.”

“I don’t care.” She pouted, crossing her arms. “None have even tried to Bond with an avian to learn more. Too much pride and stubbornness. It’s a disgrace!”

Ghrughah hummed loudly in wonder. “Am I right in assuming you are responsible for the Bonds that help you two steer an aerostat?”

“Yep!” she exclaimed happily.

“W-well, I do have a few, too…” Arennte added hesitantly.

“Because I forced you to.” She sent him a glare.

“If the contract comes to fruition, I would be grateful if you agreed to partake in a knowledge exchange,” the giant interjected, stopping their short banter. “I have problems with finding a Bond, you see.”

She nodded happily. “Sure!”

“Okay, let’s start the presentation. We are wasting time,” Zeph declared. “We will have all day to talk about partnership afterwards.”

They all nodded, so he started explaining.

“As you can see, parts of the frame’s top, the ones holding up the prototype, are flexible.” He encouraged them to take a closer look at the slight curve of two metal bars connected to the holding rods. “We will be using those spring-based, mechanical gauges to measure the forces acting on them. One unit on the scale equals half the weight of the prototype.” He gestured to four gauges affixed to the tunnel’s round walls made from plastic panels. Two were set at the top of it, and two on an enclosed side. Half of the tunnel in that section was left open.

Enjoying this book? Seek out the original to ensure the author gets credit.

The gauges were made in the likeness of the Earth ones, as Zeph suggested. A rotating pointer was a simple mechanical design, so the room for meddling was minimal which would increase their credibility.

“After the presentation, you can verify their scaling and functionality with Ghrughah. The two at the top will measure the overall upward or downward force influencing the body of the prototype. The side ones will measure the lateral tilting of the holding rods. Using those four readings, it’s possible to calculate the approximate behavior of the whole aerocraft in the air. We prepared a table of standard results for simplicity, but we can explain to you the math in detail, if you choose so.”

The twins started getting pumped up the more he spoke. It was a good sign.

“Now, Let’s start the preparations.”

The Blacksmith lifted the frame containing the prototype and inserted it into the open slot at the center of the five meters long, straight section of the air tunnel. That section was elevated, sitting almost a meter above the ground. A bottleneck-like funnel connected it further to the Mana jet engine set another five meters back.

Of course, the plastic the tunnel was built from was see-through. Kwan’s people managed to achieve at least that much when experimenting with the material.

The engine itself was on the smaller side of medium-sized models, with a diameter of almost 2.5 meters and a length of around 4 meters. Its sleek, black-metal surface was featureless, but overlapping plates that made up the nozzle regulating its output added a futuristic feel to the design. That aside, it was surrounded by pipes and wires. The clearance through the device was also much smaller than it should be, at least in Zeph’s mind, spanning maybe half a meter.

After gauges were connected to the frame and tested, Zeph caught the attention of the pilots. “Look here. The top gauges are now showing minus one unit each. Now, when the sum of the two crosses the threshold of zero, the aerocraft will ‘hover’. Theoretically, I mean. For clarity’s sake, we will now add the summing gauges,” he said and took out two rods with gauges in the middle from a nearby crate. Ghrughah connected the top two gauges with one, while Zeph took care of the side ones. The rods were screwed to the center of each main gauge – the internal mechanism automatically connected to their pointers to be able to rotate with them.

Finished, Zeph took out two files of paper from one of the smaller crates. “Here are the tables we prepared. Make sure to scan them beforehand. It will make it easier to understand what is happening. The drawings should be self-explanatory, but ask if something isn’t clear.”

The duo nodded, and Zeph left them to their devices. The next part would take some time.

Firstly, they connected three metal cords to the prototype – one to its very back, and two to the holding rods, near the bars. Then, they threaded the cords through dedicated latches on the tunnel’s wall, making sure they weren’t stuck or slack, and finally, they screwed down the last of the plastic panels, completing the encasing.

After checking everything one more time, he and Ghrughah started to saturate the construct with their Mana. While the Blacksmith used a metal cord connected to the back of the prototype, Zeph just touched the plastic surface to force his Mana-L into it. It would drastically improve the Mana-containing properties of the material.

He was losing connection to most of the Mana he was sending, and would lose even more after the engine was launched, but it wasn’t important. Unlike Ghrughah, he wouldn’t be manipulating anything, so simple saturation should suffice. But that meant he had to actually go around the whole structure to touch every section. Using Mana tendrils could do the trick instead, but it would be inefficient and would reveal his proficiency in Mana manipulation too early.

After fifteen minutes, he was done. Sustaining the saturation would be an easy task in comparison. Turning to the twins, who were standing a few meters behind the exhaust, he noticed that they finished reading.

He stepped up to them. “Done already?”

“Yes,” Arennte answered excitedly. “How long until Ghrughah-jiji is done?”

“A few minutes. But before we start, I need to make final explanations. The prototype is being saturated by his Mana to allow for material manipulation. As we mentioned, the thing doesn’t have any mechanisms inside, so it has to be operated manually. To make sure you will be able to verify the outside frame, and the resulting gauges’ readings, aren’t manipulated, you are allowed to saturate the top parts of the holding rods. Use those metal cords to do so, please, and we can start with the show.”

They did just that, and after another ten minutes, everything was ready.

Zeph smiled and nodded at Arennte. The man nodded back and picked up a black control plate laying near the engine. It was wired to the device directly.

“Please set the thrust at level four and Mana output at level two,” he instructed.

A few taps on the plate later, and a low hum filled the chamber. There were no light effects at such a low operating mode, but soon they heard the whistle of moving air, intensifying with each passing second. behind the tunnel’s exit dust billowed out, lifted from the ground and pushed in a chaotic dance towards the wall behind. The hall was spacious, yet the thrust was enough to force the air inside to circulate. Random whips of wind started playing with their clothes and hair.

Ten seconds later, the noise leveled out.

But the gauges didn’t move.

“As you can see,” Zeph had to raise his voice slightly to be heard, “There is almost no difference in forces influencing the aerocraft. The reason is, the wings’ profile is symmetrical.” He gestured for them to look at the wings from the side. “The whole concept of the lifting force depends on the wing’s shape.”

The twins nodded in understanding, looking closely at the aforementioned part.

“We weren’t able to prepare adequate measuring devices for it, sadly. But, assuming you didn’t stray too much from the engine specifications, the conditions inside the chamber should simulate an altitude of around 3 boats (105 meters) and velocity of about 4 ranges per hour (84 kph). Keep in mind that for a bigger aerocraft, the operational speed will be different. The scaling between lifting force and weight isn’t linear.” He explained.

Because it would be impossible to conceal the changing shape of the wing’s profile, they decided to present it early on to hook up the pilots. The knowledge was given freely, but not for free. They would negotiate the price later, whether the twins accepted the partnership or not.

Zeph nodded at Ghrughah and the man concentrated. The wings slowly morphed, the bottom part flattening, and the gauges reacted. After their sum reached zero, Zeph started his commentary again.

“The asymmetrical shape itself is enough to force the phenomenon. Right now, we have a vehicle able to hover as long as it has enough velocity. But there is more to it. The shape of the leading face of a wing, and the curve of the whole profile, influence the resulting force as well. Look at the table, we will use figures 3 and 4 from the first paragraph…”

After a few repeats showcasing his point, Zeph moved to the most important part. “The force generated this way is convenient because the ‘angle of attack’ of the wing’s profile has stable and yet the strongest impact. You can modulate the lifting force naturally by tilting the aerocraft lengthwise.” Ghrughah manipulated the internal framework to rotate the front wings by a few degrees, and the gauges’ pointers started moving quickly to the right of their scale. The back gauge was doing so a little slower, though. The twins synchronically oohed in surprise.

“As you can see, it’s an almost linear reaction. We are now at three times the weight of the aerocraft. Depending on the design, the vehicle can become maneuverable to the point of causing problems for the pilots because of the forces generated during the maneuvers, so keep that in mind. But that’s not all, if you roll the aerocraft sideways…” The Blacksmith manipulated the holding rods at the connecting points to rotate the plane as if it was turning, and the side gauges started to react. “…the lifting force works all the same, but at an angle relative to the surface of the ground. The aerocraft will start turning, as part of the lifting force now pushes the wings to their objective right. Of course, the drag also changes, but it only strengthens the effect.” He glanced at the pilots and knew they were already sold on the idea. All that was left, was to set boundaries.

“Let’s reset the setting,” he said to Ghrughah before turning to the twins. “I am sure you can find your own ways to rotate the aerocraft in the air like that, but the optimal method will stay with us until we finish the negotiations. To make it work, you need to work with all five wings. We will not present that part today,” he declared harshly, but the pilots simply nodded.

The ailerons were the hardest part of a wing to adapt. The simple mechanical plates wouldn’t pass the exam in Corora’s atmosphere. For now, they decided to leave that part to Ghrughah’s manipulation expertise. Thus, the multitude of plates making up the back of the wings.

“Now, for how Mana density influences the flight. Arennte, please set the Mana output at level seven.”

The man blinked in surprise. “Isn’t that too much? What is that going to simulate, even?”

“Fluctuations of that scale happen all the time on low altitudes. It’s important to understand what difference they can make. Think of it like flying over the ocean, only to hit a cloud formation full of Water Magicules. The effects won’t be identical, but you will see what an increased air density can do.”

“If you say so…” he changed a few settings and the hum deepened. The whistle of wind was cut off for a second as the dense air clogged near the neck of the funnel, causing perturbations in the airstream and blocking the flow.

The gauges plummeted to the left immediately, nearing the minus one on the scale. After a few seconds, the airstream stabilized, but the gauges’ sum was still below zero.

Not the best performance, but still a working one.

“And that is why we need to modulate the wing’s shape, not only the ‘angle of attack’.” He pointed at Ghrughah and the metal plates making up the plane waved like blades of grass under a strong wind, all wings rotating all at once at the same time. The whole plane changed shape, becoming much slicker. The wings bent sharply into almost crescent shapes, profile-wise, even the back ones followed suit this time. The gauges’ pointers suddenly sprung back to the right, going as far as up to the seventh indicator on the scale. The whole frame groaned at the sudden change.

The twins were slightly shocked by the display.

“The reaction was that drastic because we passed two critical points at once. You see, there is the maximum ‘angle of attack’ after which the aerocraft of this type will plummet to the ground. The same applies to air density and the overall shape of the vehicle. Again, the exact reasons will be explained only after the negotiations.”

The exact conditions causing perturbations were tricky to predict in this world, but the basics should be enough to at least plan around them.

“We will show you more examples in a moment. But first, the fun part,” Zeph said flatly, glancing at the Blacksmith.

The man grinned widely, vibrating with excitement. “Finally! La-Arennte, set the engine to randomized mode level three. Thrust at six, Mana output at average five!” he boomed, flexing his fingers impatiently.

The twins were taken aback by the sudden outburst, but Arennte did as told.

Releasing the monster.

It all started innocently – during the design process, Ghrughah was responsible for learning how to operate the toy plane in difficult environments to showcase its capabilities.

It was a crude imitation of the current tests in the air tunnel which guaranteed a controlled environment. They had to manually manipulate their Veils to imitate a random distribution of Mana density in the air that was passing at high velocity. Thankfully, with the winds plaguing the city for the past two days, there was no need for any enchanted devices stimulating an airflow. All they needed was a pipe system with entries set outside to funnel the air, and simple mechanisms regulating the pressure to make sure the flow was below certain thresholds.

The locals had a lot of experience with setting up pipe systems, evidently. The chaotic nature of the setting played right into their hand, too. Unpredictable airflow was desired in this case.

But as time passed, Ghrughah started to enjoy the exercise more and more. Thanks to the direct feedback from his Mana that saturated the aerocraft, he was able to master basic ‘flight’ in but a few hours. Instead of stopping here, he increased the airflow thresholds and commanded Zeph to take care of inserting the Mana himself, for more unpredictability.

Like a video games addict, he wanted more and more, until Zeph decided he crossed a line. The man was ready to call his own people to take Zeph’s place, so he didn’t have a choice and promised to create an even better version for Kwan’s entertainment park, and for him to play with.

That placated the giant. Barely.

And now, Ghrughah’s moment of truth has come. The airflow will be much faster, the fluctuations of Mana density will have drastically higher amplitude.

And there were no ailerons on the wings.

It was the beginning of a very long night. Zeph dodged the bullet only because the twins promised to strike the deal with them… after the Blacksmith finished playing.

He escaped the place quickly with relief. It was time to pay a visit to the Library.