It both sucked and was fantastic that all of the drones were completely obsolete now that she had the levitation technology. When she got back, she would start building the little boogers with stealthed features, using levitation technology to fly them like helicopters.
I know it's way late for that comment, both 'cause I'm reading an 8-months-old chapter and Lily just solved her stealth problems with
magic levitation tech... but the brain-gremlins won't let me know peace until I write this. ^^'
First, propeller designs can be rather quiet:
- MIT's
toroidal propellers are reportedly 4× quieter than current ones, in terms of subjective noise levels. Granted, that was published in 2023, so Spira couldn't have known of it when writing this
- Things like
Zipline's propellers have a more bio-mimetic design, though I couldn't find good references to quote.
Second, in a usecase where endurance matters, like Lily's overwatch and intel/recon drones, a fixed-wing design might be a lot more energy efficient and have the option to temporarily cut propulsion and glide to be extra quiet. I'm immediately thinking of flying wings there, because they are aerodynamically optimal, good for radar stealth... and I've been obsessed with them lately, to the point of wanting to design & build a CATOVL one :3
Moreover, the general shape seems to lend itself better to things like:
- having a camouflaged bottom (with plain old paint, or fancy adaptive stealth tech) while the top can have "cooling paint" (i.e. cheap radiative cooling) and/or PV panels to minimize the fuel expenditure even more (assuming this is still electric propulsion, and something crazy like a jet engine powered by heat from a microfusion cell)
- carrying instrumentation that needs a bunch of surface, like an antenna array for electronic warfare and surveillance (incl. radar), multiple optical sensors to recover depth/distance information, etc.
While Fallout's miniaturized nuclear power makes endurance a non-issue, Lily is chronically short on those devices (at that point in the story, at least, haven't yet read further) and not using them in the drone fleet would both immediately give a bunch of useable fission batteries (IIRC that's what the drones use?) and remove the bottleneck on expanding the fleet; given her plans to use it for ubiquitous connectivity (and surveillance? 😼) that seems like a major win.
She'd need alternative power sources, but with her incredible manufacturing capacities with carbon, she should be able to make really good H₂ fuel cells. She already has a nuclear power station distilling water, so that would be easy to tack on... and really efficient, since a good part of the energy for electrolysis can be provided thermally, using waste process heat, rather than electrically; yay for co-generation!
That said, I think quadcopters made sense for Lily as an early-stage tech:
- She'd know about them, based on her memories as a contemporary engineer.
- They are much simpler to design "from scratch" than fixed-wing aircraft, with the main issue (compact and relatively light-weight energy storage) already solved by local tech, and Lily needed something
now.
- "The Spider of Tannhauser Station" presumably wouldn't know about aircraft tech: it can't be used in space, nor inside most space stations (they presumably don't have wide open pressurized spaces) and it would likely be obsolete tech in the few places that have suitable atmospheres.
[The kamikaze drones] weren't that fast either; she could have designed a faster design, but if you designed an airfoil for a high-speed cruise, that meant it had a really poor low-speed performance. And that would have meant they wouldn't have been able to be launched just by pneumatics; an air cannon just wouldn't have gotten it up to speed fast enough by itself to reach steady flight, and it would have crashed on launch. Her first three designs met this fate. She'd have to have included a rocket assist for the first phase of flight to get them up to speed, and Lily didn't have any way to manufacture solid rocket motors at the moment
H₂-pawered launch and airbreathing engine? 🥺
TBH that's just because I would want to see it, rather than strict practicality: advanced engines are (presumably) more complex for Lily to print than motors, and might require costlier alloys to handle the high temperatures unless she can make all the internals out of graphite or something. (though batteries are expensive to make too)
ie.social
interestingengineering.com
