Developing a Military Reconnaissance System

[Core Room]

"First, the military application of the information and communications system: reconnaissance and communication."

"Director, until we first spot the pirates, there's nothing to discuss. At present we're using the dungeon's 'height' as a watchtower. The distance to the horizon is currently about 60 km; once we pass the 100th floor in the future it'll be around 80 km, and once we reach the 1,000-meter class it should exceed 100 km."

"Isn't that enough?"

"Because there are limits to camera performance, we can't tell whether they're pirates or merchants. Realistically it's about 20 km. When it isn't clear, further reconnaissance is needed."

"And that's where the drone comes in?"

"Director, if it were possible to summon a bird as a dungeon monster, then giving it a camera and sending it out to scout would be best of all. Do you follow?"

"A bird, huh…"

"If we limited operations to within the dungeon's sphere of influence, it needn't be a bird; a monster forced into flight by a unique law would do just as well. If we summoned a flight-capable angel and gave it a name, it could speak too, and could be put to all sorts of convenient uses."

Angels belong to the "Heavenly Realm" of the Six Realms. Incidentally, Marie says they are "useless dead weight that only runs up costs" and that "they don't come to a good end (the Five Signs of a Deva's Decay)."

"But if it left the sphere of influence, it'd be unable to defy the laws of physics and probably plummet."

"One that grows corrupt is a fallen angel, but one that takes a fall, what sort of angel would that be?"

"A con-angel?"

"… Angels aside. In this dungeon, where summoning flying creatures is effectively impossible, aerial reconnaissance is difficult. Which is why the personal secretary keeps insisting on horses as the next-best plan, but if we can obtain a drone, it'll prove its worth at reconnaissance."

"Those machines with four or five propellers, was it?"

"That's the type called a multicopter. Multicopters have the major problem of heavy constraints on fuel economy and flight speed. For example, with a 30-minute endurance and a top speed of 40 km/h, the operating radius is at most 10 km, and in practice it's limited to a few kilometers."

"What else is there?"

"Fixed-wing craft, essentially an unmanned airplane, but they need a runway to take off and land, and since they stall at low speeds, that imposes its own constraints on reconnaissance use. We have no communications satellite, so we can't communicate beyond the horizon, and autonomous control is beyond us, so we can't really make the most of their strengths. Landing in particular is highly difficult, so you'd have to be prepared to treat them as disposable. Then there's the tiltrotor, which combines a helicopter and a fixed-wing craft, but perhaps because the technical difficulty is so high, you almost never see one among drones."

"They all have glaring drawbacks."

"An airship is useful for reconnaissance, but it has its drawbacks: it's weak to wind, and since there's no helium, you'd be using hydrogen, which is flammable. True, inside this dungeon's buildings no fire can break out, but there's little point in flying one indoors anyway."

"Lastly, the ornithopter combines a fair flight speed, hovering, and long loiter time, but it has the problem of extremely high technical difficulty. A bird can weigh on the order of kilograms, but an ornithopter is a few hundred grams at most. What's more, for filming purposes, the flapping causes heavy vibration, and attitude control is a headache too."

"In short, since every last one of them lacks practicality, it really does come down to the horse being best. Is that it."

"Regrettably. Still, horses are hard to obtain, we haven't got a single one even now, and breeding them is no small labor, whereas a drone you can simply make. That's a strength. And since it isn't alive, there's no ethical problem in running it into the ground. That's a strength too."

"And so you'd obtain it as a partwork encyclopedia, like that aircraft-carrier plastic model lined up on the bookshelf there?"

The old familiar 1/700 Casablanca-class escort carrier.

"The first generation weighs a full 1.5 kg and has only 10 minutes of flight time, so it doesn't suit this dungeon. But there are all sorts of drone partwork encyclopedias themselves, so if we order in a newer model, it'll be useful, even if inferior to a horse. And so, I've prepared a prototype."