Chapter 105: Ways to Use Monster Materials

After returning to the laboratory with several monster materials, Isamu and the others immediately began working on improving the carriage wheels using those materials.

Since returning from the Inochenti territory, the three magic circle geeks, who had been holed up in the research institute, seemed to have tired of her company. Even Orihime, who had been frequenting the knights’ quarters, seemed to have noticed that they were up to something different, so she rarely came back.

“Now, there are two main effects we can achieve by improving the carriage wheels. One is to improve the ride comfort, and the other is to enhance performance. Even in my original world, initially, we used wooden wheels wrapped in leather or attached with metal. But with the advent of rubber and air-filled wheels, there was a dramatic evolution. In the era I came from, carriages ran at more than twice the speed of horses running at full speed. I believe that was possible because of rubber tires.”

“Twice the speed of a galloping horse…? Certainly, if you ran a carriage at that speed, the wheels would fall apart before you even worry about comfort.” 

Eto sighed upon hearing Isamu’s explanation.

“Yes. So this time, rather than focusing on performance, I want to improve the ride comfort. The current uncomfortable ride is mainly due to running on hard cobblestones with hard wooden wheels, directly receiving the vibrations and shocks. Although it was somewhat improved by using leaf springs and metal leeches as dampers, if we can reduce the shock transmitted to the wheels in the first place, it should be even more comfortable.”

“Certainly, if we can improve that eternal rattling, it would be much better.” 

Wilhelm grimaced, recalling long-distance carriage rides.

“In my original world, the wheels were a dual structure, with an inner bag made of elastic and resilient rubber filled with air, wrapped in a hard rubber exterior. But it’s impossible to do that here… So, I plan to adopt the dual structure and change the filling material.”

As Isamu explained, he started drawing a cross-section of the wheel on the paper.

“The outer layer should prioritize durability as it directly touches the ground. Currently, we have two candidates: the tentacle of the Roper and the skin of the Rock Worm. The basic structure will be a dual structure stuffed with Farm Fungus inside.”

“I see. If that works out well, it should be much better than the current wooden wheels. And the processing shouldn’t be too difficult.” 

Eto nodded in agreement with Isamu’s explanation.

“Before we get into the processing, I have a question. Aren’t monster materials not widely used here? They are often used for food, but apart from parts like fangs, horns, tough outer skins, and skeletal structures, most other parts are rarely used, right? Even this Farm Fungus seems like it could be good for carpets or cushions…”

Despite the variety of monsters with various characteristics, it was strange that except for a few parts, most of them were not utilized.

“Hmmm… It’s because it was common to throw away those parts in the first place, so I never really thought deeply about it…” 

Eto crossed his arms, pondering.

“There could be several reasons, but basically, monsters are threats rather than resources. Apart from goblins and orcs that attack cities if left alone, adventurers don’t hunt down monsters unless they are valuable for some reason. So, if there isn’t a clear use like food or fur that can be used for various things, the Guild won’t offer much money even if you bring them in. Since adventurers also need to eat, they end up hunting monsters that are valuable. It would be convenient if new materials could create new things as Isamu-san said, but since things are getting along fine with what we already have, there’s no need to go through the risk of obtaining monster materials for research. Also, there are many types of monsters, some of which are poisonous or have adverse effects on other materials. And there are so many of them. While it might be interesting as a research subject, the risks outweigh the benefits.”

Willem, speaking like a true researcher, explained his hypothesis based on the situation in this world of Ethersia.

Probably, what Willem said was hitting the mark.

The power balance between monsters and humans is so skewed towards monsters that there has never been much leeway to hunt them for materials.

“Ah, speaking of which, there’s also a problem when you consider them as materials.”

Eto, who was listening to the story, also seemed to remember something.

“Currently used monster materials are mostly items for which processing and storage methods have been established. Solid Beetle used in the Bastet series, for example, can be used as it is without any processing. Things like fangs and horns are also in that category. But for things like skin and fur, if they’re not processed like tanning, they’ll deteriorate quickly. But since the handling is similar to animal skins, it’s not a big problem. However, for other materials, most of them don’t have established storage methods, even if processing methods exist. Without being able to store them, there’s no point in trying to use them, and they’ll remain unused forever. Things that don’t last long can’t be used as tools…”

“I see… Monster materials are indeed raw materials, fundamentally. So, the hurdles are higher… Wait? Does that mean we have to consider those aspects for the materials we’re using this time!?” 

Isamu suddenly realized.

“”Hmm, that’s what happens.”

“That’s included.”

The two of them smile bitterly at Isamu who is panicking now.

“I see… I’ll need to put more effort into this.” 

Isamu said with a determined smile. Steeling his resolve.

Anyway, for now, the priority is to determine if they can be used as tires. So, they put aside the issue of storage methods and began prototyping.

Regarding the Farm Fungus, since it just needed to be processed to an appropriate size and stuffed in, there weren’t many issues. But the material used to wrap it required some processing.

“Hmm, are Roper tentacles hollow…? Alright, let’s try stuffing them with fungus first.” 

Isamu said as he stuffed the fungus into the tentacle of the Roper to be used as a tire.

After binding one end tightly, he started packing the chopped fungus tightly inside.

After a while of packing, a long, sausage-like object with a deep green color was completed.

“Eto-san, how’s the wheel coming along?” 

While Isamu was making a makeshift rubber tire, Eto had been working on modifying the wheels.

“Should be about done. If I carve too much, it won’t hold up.”

Isamu had asked Eto to carve grooves on the outer rim of the wooden wheels to make what’s called a rim.

This was because if we simply put rubber-based material on the outside of the existing wheel, it would easily shift inward or outward.

As Eto said, the strength will be reduced, but it’s a prototype so it’s not a problem.

Once you know that this method works, all you need to do is re-make a thick one specifically for the purpose of digging the rim.

“Oh!! As expected of Eto-san, it’s perfect!!”

Right there, was a carriage wheel with a neatly carved groove.

In the case of tube-type tires where air is pumped in, most of them rely on that air pressure to press the tire against the rim and hold it in place.

However, since they weren’t using air, if they used that method, it seemed like the tire could easily come off. But since this was just a prototype, they decided to overlook that issue.

Eventually, they would need to add an additional feature, like a matching wheel.

After lightly winding and adjusting the length, they started packing the Roper tentacle, filled with fungus, tightly into the rim.

Since the tentacle was wider, it was fairly securely fixed when forced in with some effort. It might look a bit awkward, but since they were just checking the effectiveness, it shouldn’t be a problem.

At a glance, it didn’t look too bad, as if a rubber tire with a thickness of about three centimeters was fitted over the outer diameter of the wheel.

“It went pretty well for a first attempt, don’t you think? Since it’s a prototype, let’s not make all four right away. Let’s make just one more and try replacing one of the cart wheels for a test run?”

“Sure, let’s do that. We can attach it to the carriage last.” 

After spending about an hour finishing the second prototype tire, when they went outside to replace one of the cart wheels, they found Mizeroi and Tiramisu working on something in front of the cart.

“Huh? Mizeroi-san and Tiramisu-san. What are you doing here?”

Mizeroi is my personal bodyguard, so it’s not unusual for him to be near the laboratory, but I didn’t expect to see Tiramisu here.

“Oh, Isamu-dono. I was just exercising by joining in with the knights’ training, and then the sensei came by just now. So, since she seemed to be calling for Tiramisu, who was with me, we followed her here. Then, she started scratching at the cart with her forepaws, so I brought it out here like this.” 

“Ssu!” 

“I see… I was actually working on a new wheel for the carriage. Orihime must have heard about it and sent you both here.” 

“Nyah!!!” 

As if to ask, Orihime climbed onto the back of the cart and let out a cry.

“Thanks, Hime. This will make changing the wheels much easier.”

 Isamu said as he thanked Orihime while patting her behind the ears, and she responded with a small meow.

First, to confirm the current ride comfort, Eto, Isamu, and Orihime boarded the cart.

Mizeroi pulled the cart, and if additional speed was required, Tiramisu pushed from behind.

“Let’s go then!”

With that, Mizeroi began pulling the cart. The cart, without even leaf springs, advanced over the cobblestones. Naturally, it rattled and shook considerably.

“Ahh, I see. So, this is how it feels.”

After running for a while, they made a U-turn and returned to the front of the laboratory.

“Since there are no leaf springs, it’s quite expectedly a stiff ride. Let’s see how much it changes…”

Then, with the help of the two knights, after changing the cart’s wheels, Eto and Isamu boarded the cart again. Perhaps having learned from before, Orihime was perched on Mizeroi’s shoulder this time.

“Alright, here we go.”

Once again, Mizeroi began pulling the cart.

“Hmm?”

As he started pulling, Mizeroi let out a small grunt.

“It feels a bit heavier than before.”

“Heavier, you say…”

“Yes. Especially at the start, it feels heavy. Once it gets moving, it’s not as bad, but… Let’s try increasing the speed a bit.”

“Yes, please.”

“Ah, the vibration is significantly reduced!”

“Yeah, it doesn’t feel as hard anymore.”

Moving at about the same speed as before, they could now better discern the difference. The rough shocks and jolts were considerably mitigated.

Considering it was a bare wooden surface compared to one covered with elastic material, such a difference was only natural.

While it might not compare to tires utilizing air, it seemed to provide a significant improvement over just wood.

However, there was a concern.

The immediate “heaviness” Mizeroi mentioned upon starting.

This was likely due to increased friction with the road, rather than the weight of the tire.

In broad terms, wheels serve as mechanisms to convert the resistance encountered when moving objects placed directly on the ground (sliding friction) into a smaller resistance (rolling friction).

Also, unlike the wheels of automobiles that need to manage driving and steering functions, the role of cart wheels, mainly being pulled, is quite simple.

As long as the wheel adequately supports the cart without slipping and provides some resistance to turning, smooth rolling is ideal.

While higher speeds would require functions like turning and stopping, they weren’t as crucial for carts that didn’t achieve high speeds.

In that sense, hard wheels are more effective at reducing rolling friction. Therefore, the current wooden or metal wheels are arguably reasonable.

However, once people and cargo are added to the cart, things become different. The need to absorb vibration and shock arises.

Even with suspension and spokes to absorb some of it, the direct impact on the ground from the wheels can’t be ignored.

In such cases, the wheel needs some degree of flexibility.

However, soft materials generally increase friction. And when friction increases, more force is required to move.

Mizeroi’s remark about it feeling heavier likely stemmed from the increased friction caused by the soft, elastic wheel.

As there are often trade-offs involved, what to prioritize depends on the desired outcome.

What Isamu and the others most want to achieve is an improvement in ride comfort. High-performance grip and braking aren’t necessary. Being equal to or better than wooden wheels would suffice.

However, they also want to minimize the increase in resistance when pulling the cart. Finding the compromise between ride comfort and resistance becomes their task.

“Hmm, it’s frustrating not knowing how much this increase in resistance will burden the cart. People’s perceptions of pulling force vary. But by making several prototypes and using Mizeroi as a reference, I think we can learn a lot, don’t you think?”

“Certainly. Since we could feel an improvement in ride comfort even with this first one, let’s use it as a reference point and try making both harder and softer ones.”

What began as an escape from reality through replicating magic circles on armor led to a full three days spent on creating prototype wheels for the cart.

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