Reasons why air travel isn't feasible, but ground travel is?
My story takes place on an Earth-like, inhabited world that is far larger than Earth, has roughly 110% of Earth's gravity, and has unusually high (and generally unexplained) EM emissions permeating its atmosphere sufficient to disrupt radio transmissions beyond a few miles.
Humans from earth have begun to settle the planet, primarily big corporations seeking to exploit the planet's rare natural resources. Wheeled transportation between settlements isn't very practical due to the great distances between settlements.
My story revolves around high speed ground-based transports, so I'm looking for plausible reasons or obstacles that would help explain why traditional jet/rocket/prop-based air travel is not practical.
Important notes:
Atmospheric pressure at the surface is roughly similar to Earth's (another problem I'm still working on), but with a higher ratio of nitrogen to oxygen. Mean Climate, radiation levels, etc. are also comparable. Much of the time, humans can survive outdoors on the planet just fine using rebreathers, although both the daily and seasonal temperature variance tends to be a bit more extreme than Earth, and the days are shorter.
The first settlements on the planet were exploratory, inhabited originally by scientists and supporting bureaucracy & infrastructure. These early settlers discovered trace quantities of a previously unknown compound with certain highly valuable properties. This gave rise to multiple competing private interests investing heavily in tracking down concentrations of the stuff large enough to make harvesting it worthwhile, despite the distance between said deposits and other environmental challenges. Many such clusters have been found but tend to be very far apart (and a single corp tends to claim a large area whenever a cluster is discovered in hopes of finding more).
The ground-based transports actually levitate in a manner similar to a hovercraft, but using a hypothetical thrust technology (which is dependent upon the same resource everyone's hot for in the first place). This gives them enough lift to easily clear obstacles like rocks and shrubbery, and even water -- and taller obstacles, too, for short periods -- but not enough to actually fly. A variety of more conventional engines are used to provide directional thrust.
This post was sourced from https://worldbuilding.stackexchange.com/q/92857. It is licensed under CC BY-SA 3.0.
2 answers
Okay, I'm going to take a stab at this, and run the risk of having to delete this answer if it turns out my assumptions are wrong. Given what's in the question thus far, though, I think that an obvious choice would be the fact that...
It's much easier to transport large amounts of material on ground than by air.
Both ventsyv and tuskiomi discuss this in light of atmospheric pressure, but I think there's a bigger issue at play: Having to lift stuff to move it often ends up requiring more energy than just moving the same stuff.
Given that this is about humans colonizing an alien planet, I think it's safe to assume that they have access to most things that we take for granted today. Maybe not ready access, but access no less.
If you can clear out a ground path sufficiently to transport things on the ground, and maybe even build even a rudamentary "highway" system (which does not need to involve paved surfaces; this could be a railroad highway system, for example), then going a few hundred kilometers per hour is certainly practical, especially if the atmosphere is thinner than Earth's (resulting in less drag); and you don't need to spend energy to lift it all the way aloft just to bring it back down again.
There's a reason why lots of Earth transportation is done by land or sea, rather than air, unless speed is of the essence (at which point you accept the higher cost).
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Unpredictable weather with lots of microbursts, wind shear, tornados, and other unfavorable winds.
Wind shear is one of the most dangerous things for an aircraft. Thankfully they are generally rare, on Earth. If flying isn't a question of if there will be a wind shear, but how many there will be, flying wouldn't be something that you'd want to do.
Very low temperatures and ice clouds to cause constant wing icing.
Airplanes have wing deicers, but at some point the icing can be so bad that they can't compensate.
Treacherous terrain, which would make emergency landings impossible.
You don't want to fly if any attempt at emergency landing is going to be fatal. High mountains and other dangerous terrain would be a big problem if it covers the entire surface, especially if the weather or other things make emergency landing a higher probability.
Combine this with unpredictable weather and it gets real iffy. No one wants to be slammed into a mountain by a downdraft or fly into a cloud that's full of rocks.
Huge flocks of birds or other flying creatures that would foul engines.
If there are flying creatures that are either accidentally or purposefully suicidal, then flying would be basically impossible.
Heat can ground an aircraft just as easily as cold.
Fuel shortage.
Flying can take a long of energy, and so not having a dependable, clean, fuel source would be a big problem. If the planet has no petroleum, and bio fuels aren't being produced fast enough, then that would make flying difficult.
High solar and atmospheric radiation
The higher you go, the more radiation you receive. In the event of a solar flare, there can be a big spike in radiation. If this planet had a very active star then that could become a big problem for any aircraft without shielding, and shielding is very heavy. Whatever causes the atmospheric radiation could also be the source of the heavy EM interference.
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