The Drone That "Ends Up" Self-Destructing

[Tier-Group 3 Rooftop Garden]

"This aerial-survey drone weighs in the 200-gram range, about as much as a pigeon, yet it boasts pigeon-grade flight performance: a cruising speed of 50 km/h, a top speed of 90 km/h. Its flight time is inferior to a pigeon's, but still runs to several hours. A fine piece of work. Mostly thanks to a lightweight, high-capacity lithium-air secondary battery."

"And what manner of high-performance 'battery' does a pigeon run on, I wonder."

"In terms of 'performance,' a bird is the superior article to any drone. At any rate, I've cranked the dungeon-side transceiver to high output, so we can communicate out to the distance of the horizon."

"There's an antenna on the Tier-Group 3 rooftop, about 40 meters long, but…"

"That one's the 3.5 MHz band. If anyone in this world happens to be running amateur radio, we could communicate by keeping watch on the 3.5 MHz band. The drone, on the other hand, uses the 2.4 GHz band, which travels in straight lines and is weak against obstacles, so it's unsuited to operations beyond the horizon."

"So at present, by the math, that's a range of about 60 km."

"Today, doubling as a test flight, I'll send it west, all the way over Kasumigaseki. At top speed it would take roughly 40 minutes, but to spare the battery, make it an hour."

[Core Room]

"Kasumigaseki should be coming into view soon. Director, that must be Kasumigaseki."

"The eastern edge of the plateau across the dried-up river, in other words the side nearest us. There's a dry moat and an earthen rampart, so it looks like a castle, but I don't see anything resembling a keep."

"Master, couldn't that two-story, warehouse-looking building at the highest point be the keep? And the town would be on the castle's west side. Population a few thousand, I'd guess. It doesn't have the air of a government district at all."

Marie was speaking of Kasumigaseki.

"Doesn't look to be a very large town. No sign of paddy fields. The dry fields look poor, too. And, just as I thought, there's no city wall ringing the town."

In Europe and in China alike, the common wisdom was that a city had a wall. Walling in the surrounding farmland, let alone an entire nation, was naturally difficult, and only the Roman Empire and a handful of Chinese empires had ever managed it.

"After this I'll set the drone to autopilot, then switch back to manual once it returns, and… ah, there's another town about 3 km to the west."

"So Kasumigaseki was a twin city."

"The western one is considerably smaller in scale. The eastern one must be Kasumigaseki proper."

[Core Room]

The drone made its way back to near the dungeon.

"Its altitude is dropping somehow."

"Mint, can you get the drone on this camera over here?"

"It's too far, it's nothing but a dot… ah, it flashed."

"Communication lost… it crashed, did it."

"That makes it a self-destruct drone, then."

"The battery's lithium and the airframe's a magnesium alloy, so, yes, I suppose it's flammable enough…"

"Mint, if it isn't going to land anyway, then we may as well treat it as a disposable fixed-wing aircraft. Load it with gunpowder and it could double as pirate extermination."

"Was there a partwork encyclopedia for model airplanes, I wonder… something like Weekly Build the Type Zero Carrier Fighter?"

"Does a plastic model part come with every issue, like the carrier on the bookshelf?"

"It's the collect-the-parts-and-assemble type. But since it isn't all that large, loading gunpowder and ramming it into pirates would lack punch. We can divert fertilizer for the gunpowder's raw materials, and if we compound it inside the dungeon it won't explode."

"It's just, well, the Zero fighter has this kamikaze-attack feel to it that sits a little oddly with me."

"Master, 'kamikaze drone' is a perfectly ordinary term, and it's an unmanned craft, so there's no need to fret over it that much."

"Director, to load enough gunpowder for lethal force, the craft has to be enlarged to a certain degree. In that case, the lightweight aide-de-camp scribe could ride aboard, and since a Named monster can be revived, in theory a self-destruct attack would pose no problem at all."

"Mint, I am not riding any such contraption. An unmanned craft will do perfectly well."

"Well, even so, the problems are piled high. And unmanned or not, it's no different from a cruise missile."

"In the end, given the constraints of our industrial base, the horse is still the best option for now. Though this self-destruct drone should be useful as a reconnaissance aid, at least."

In truth, Kasumigaseki was the western town, and what stood just across the dried-up river to the east was the castle and castle town of the local feudal lord.