While flying can generally be assumed to be done in a straight line, factors change this, though this depends on the mode of travel, as what affects a dragon wouldn’t affect a Boeing 747. Mountains can be tall enough that they must be circumnavigated. Real birds struggle to get over the Himalayas, for example, because the air is thinner. Dragons are often depicted as all-powerful, but describing their difficulty in climbing over mountains is one way to make them more realistic. This is one reason, along with rain shadows, for characterizing any land features we’ve created; in this case, we’ll decide which mountain ranges are this tall (hint from Chapter 4: the tallest peaks are in the interior of a continent, not on its coast).
Hostile territories can also change flight patterns, whether that hostility derives from other animals or sentient beings like humans with missile weapons. A lone dragon might fear to fly through an area inhabited by other dragons, if the latter are territorial or of a hostile variety. If the dragon is unafraid, his rider might be more cautious.
Politics can also cause hostility. A dictatorship might have outlawed all dragons, for example, that aren’t ridden by its own military so that borders are closely watched. Being caught could be a problem. While some might attempt passing over the territory using flight or subterfuge, some will simply go around. In such cases, we’ll need to figure out the shortest path that is not a straight line.
All flying animals that are depicted as being ridable are imaginary. The likelihood is that none of them would get off the ground with a rider, but there’s no fun in that. We must take being realistic with a bigger grain of salt than normal, but the useful details and considerations that arise from trying to be realistic can make our work more believable.
Except for mountains, flying animals are unaffected by the terrain, whether that’s roads, forests, rolling hills, or deserts. Flying low changes things a little, as foliage may hide threats, but we’re focused on speed here, not dangers except as those that affect flight paths.
When deciding how far (and fast) invented animals can travel in a day, it can help to start with understanding what real Earth birds can do. A carrier pigeon can fly about fifty miles per hour and cover seven hundred miles in a day. Hawks reach twenty to forty miles per hour during migration. These guidelines can help us determine the speeds and distances of our invented fliers. If we have a species that is humanoid with wings, aerodynamics will ensure they fly more slowly than birds. Their maneuverability is also reduced so that a giant bird should have little trouble catching and killing our species, unless the latter is well armed with missile weapons. For these reasons, flying low and hugging treetops and mountains is wiser for our humanoid character than open air unless they have no reason to suspect such a foe. The sight of such a threat should prompt one to seek shelter.
Whether we call them airships, blimps, or dirigibles, these aircraft use buoyancy to stay aloft. This chapter won’t focus on the differences between them but rather how fast they can travel. The larger airships like the Hindenburg have higher speeds and other capabilities. The Hindenburg before its demise could reach 84 mph (135 k/mh), but smaller blimps are a bit slower—their maximum speed is 70 mph and with a typical cruising speed of 30-50 mph. The limitation is inherent in the shape and design; using a bigger or more powerful engine won’t change this.
As opposed to a balloon, they are maneuverable. The large ones can ascend as high as 24000 feet (7300 meters), which means they can theoretically fly over any mountain range on Earth. However, their payload is reduced when that high and they mainly operate between 1500-8000 feet (460-2500 meters), though the Hindenburg typically did so under 650 feet to stay below clouds and monitor them for storms. The purpose of the flight will determine their altitude, as a passenger ship might sail lower to provide views while a surveillance blimp might be higher to avoid detection.
When planning a trip for our characters, we can assume a straight line unless we have some reason not to do so, such as the avoidance of a storm or hostile territory. Airships must refuel and this could restrict their uninterrupted flight to 24-50 hours, but the Hindenburg could fly over 100 hours, typically when crossing an ocean.
Hot air balloons drift with the wind. They cannot be propelled through the air and their flight path cannot be controlled beyond a limited degree. Their speed is also rather slow, such as 3-6 mph for commercial flights, which range from 3-10 miles long and take roughly an hour. Longer trips are possible as the Earth has been circumnavigated in a single trip more than once; fuel, supplies, assistance, and navigator skill are the requirements for such a feat. For world builders, we mostly need to know the balloon’s air speed and what sort of trouble our characters might get into if the flight doesn’t go as planned, but this will depend on landscape.
There are many variations to planes and engine types that will determine how long it takes to travel between two locations by aircraft. This includes fuel capacity, wind, and the plane’s purpose, as a passenger jet is far slower than an F-16, but also far faster than a crop duster. The variety is extreme enough that trying to summarize this may not serve a world builder well and has been omitted from the book.
What we need to first do is decide on the technological level of our society and what sort of plane we need (passenger, fighter). What’s the purpose in our story, and do we want our characters to have a plane that suits that purpose or not? Perhaps only a two-seat propeller plane is available but they’d prefer a fighter jet. We’ll also need a sense of how far they need to go. From here, we’d Google the plane type, learn its typical speed and fuel capacity, and get a sense of how long a trip might take if done in a straight line.