Cannon: a large hollow tube used to accelerate a projectile, usually by means of expanding gases. While it’s not often thought of as a means of transporting people through the atmosphere, it can be done. Circuses have been showcasing “human cannonballs” for a century and a half, but their modest devices have very limited range. More is possible. Electro-magnetic cannons use a series of powerful magnets to accelerate a metal projectile, and a big enough one could launch a capsule with human occupants.
Tech Level: Low, if you do it with gunpowder or flammable gases. High, if you do it with fancy magnets and superconductors.
Appeared In: Jules Verne’s From the Earth to the Moon. If you think that’s more spaceflight than air travel, a more modern example is a Canadian cartoon called The Boy. A clever kid and his muscular minder were launched to trouble-spots all over the earth in a fluid-filled spherical capsule fired from an underground (steam?) cannon.
For Your Plot: Physically draining, I would imagine. Also, what if you miss the target? I hate when that happens.
Cluster Balloon: the proper name for a bunch of weather balloons tied to a lawn chair. This is aviation at its most basic, and it’s blinding in its simplicity. You just need balloons, a generous supply of helium, and nerves of steel. Kids, don’t try this at home. But lest you think this is the stuff of suicidal scofflaws, here’s a link to clusterballoon.com where you can read about record-breaking flights in an American registered aircraft of this type.
Tech Level: Low. Although the modern practitioners prefer latex weather balloons and helium, it could be done with hot air. I class it as suitable for post-apocalyptic, alternative history or time-travel. Hydrogen filled dinosaur bladders, anyone?
Appeared In: The Disney/Pixar movie Up. Trailers here. They get bonus points for using party balloons.
For Your Plot: Even more difficult to steer than a hot-air balloon, because climbing and descending are limited by how much ballast you can drop and how many individual balloons you can afford to pop. Your hero could end up anywhere. Unconsciousness and even death by hypoxia is a risk if you fly too high, and baby, it’s cold up there!