I am considering whether to make a fairly major change in my campaign world and add the presence of a number of airships.
I'm not thinking of making them common and ubiquitous, but just wide-spread enough that they'd have some economic and social impact.
For example, there's a group of gypsy-like travelers in my campaign world known as the Shalani. Across one swath of the campaign world there are probably five or six thousand members of their tribe. If that group owned 10-12 airships and could use them to travel back and forth from (essentially north-east, central and south america), what impact would that be likely to have on the kingdoms that they travel among?
What social changes would easy but infrequent travel be likely to create? What economic changes? What points am I NOT thinking of that could cause me trouble?
What have airships done for your campaign world that you really liked or disliked? Fill me in!
If the airships are fairly rare, many kingdoms are likely to give a king's ransom for the ability to manufacture these ships. If not, then taking them by force is a major incentive, but it's dependent upon whether the kingdoms have the capability.
If airships exist in a relatively low-magic world, it makes acquiring them at any cost even more important, because traditional defenses of city walls, etc are important against mundane attacks, but against an airship that can bombard from above, there's very little that can be done about it. In addition, many kingdoms are likely to just have them destroyed so as to avoid having their enemies having them at their disposal as well.
In high magic campaigns, airships would make a nice addition to a king's military, but if they can acquire flying carpets, high level wizards, and multitudes of magic items, this probably not too much of a concern unless airships represent a cheaper way of doing things.
Economically, it depends upon how fast and durable your airship is. If your airship crawls, then getting goods by ship or land are still likely to be more viable. If airships are worth a kingdom, they aren't economically viable either to move goods. If they are costly to maintain, another reason to not use them for supply logistics.
Other notes is what kind of threat do airships pose to creatures that have the natural predisposition to flying? A dragon knows that he can probably outfly a castle's defenses or knights on horseback and has the advantage of taking the fight to puny creatures on the ground, but when he sees a flying ship that's outfitted with harpoons, catapults, ballistae, etc, he won't be amused, because now he knows that ship's crew can take the fight to him on their terms. This is something that dragons are likely to unite against.
With a fantasy campaign of variable levels of magic, an impact of an airship can be the ultimate weapon that every kingdom would be willing to go to war for or another way of transporting goods.