Airship

"Grimnoir used dirigibles because I wanted to have cool dirigible fights. That was it. However, then I had to tweak the rules in a way so that their use made sense and felt organic and true to the world. I had to look at why they lost to heavier than air craft in real life, and then add something which would have kept them competitive."

– Larry Correia

Airship refers to two types of flying machine, both popular in fantasy works.

In the real world, an Airship is a lighter than air vehicle with a rigid frame that gets its low weight by being filled with something. Historically the options are/are: helium (expensive, subject to trade embargos), hydrogen (even lighter and cheaper, but highly, highly flammable), or hot air (used in balloons since the 1780s but not airships till the 1970s), but anything with a density less then of your normal atmosphere would do the trick. If your on a world with a lot of airships presumable the atmosphere is denser. In theory nothing is the best lifting agent: A vacuum would have the highest possible lift but vacuums heavy pressure vessels to keep from imploding, The Kharadron Overlords airships actually resemble these kind's of designs. It also needs some way to can propel itself with some kind of force, typically a propeller and typically with an internal combustion engine since steam engines tend to be too heavy. Their practical use was largely restricted to the time period between the start of the first World War and the 1937 Hidenburg disaster that scared people away from airships, with World War II’s rapid development of heavier than air aircraft putting the final nail in their coffin. Their only practical use since has been their virtually non-existant minimum speed (which is based on local atmospheric conditions) that allows them to see (observation) and be seen (advertisement) for long periods of time with minimal fuel use. Since they were only used for a relatively short period of time and look pretty cool (while making pretty explosions if filled with hydrogen), Urban Fantasy loves using them to demonstrate a work is set in the interwar period, and/or alternate history where the airship lasted longer.

In high fantasy, an Airship is a sailing ship that, instead of (or in addition to) sailing, flies by magic or quasi-magical science. Since making something so non-aerodynamic fly is blatantly implausable, it’s typically a mark of a civilization that is highly advanced magically.

Crimson Skies

Crimson Skies is a setting created to facilitate air pirates and prime example of airships as part of alternate history interwar. Airships serve the role of carrier to heavier than air craft, an expansion on a handful of experimental ones in the real world.

Eberron

Eberron’s airships take elements of both types, with the aesthetics of high fantasy airships (befitting of Eberron’s possessing “wide magic” to the point it’s a science), but serving much the same role as an urban fantasy airship (befitting of Eberron’s interwar influences). Constructed of soarwood, a “naturally” lighter than air wood, and propelled by a bound elemental, they were created during the last part of the Last War (less than 10 years before the standard starting point) by House Lyrandar with the aid of Zilargo’s elemental binders. The bound elemental requires the captain have the Mark of Storm, which almost entirely limits them to being controlled by Lyrandar, and while foundlings and excoriates exist, they’re still built exclusively by Lyrandar.

The existence of airships is quite a concern to House Orien, as it threatens their monopoly on travel that their Mark of Passage has ensured them till relatively recently. To deal with this, they’ve been making greater research into reducing the cost of teleporation and making airships that don’t require elemental binding (or, at least, will work for the Mark of Passage like the Lightning Rail does). An obscure web-article actually confirms the possibility of making airships that will work for anyone, as it includes one that is an artifact of the long lost Giant civilization.

Final Fantasy

While it’s a video game, Final Fantasy is getting noted here because its depiction of fantasy airships is a major influence on how virtually anything uses them. Looking like a normal, wooden, sailing ship with propellers on top and a few behind, and in many games actually being upgraded from such ships. In most games these vessels are exceptionally rare artifacts from ancient civilizations or recently constructed masterpieces by the local mad scientist whose name is always "Cid". They are typically obtained by the party during the mid-game and allows nearly free travel of the world map, with few obstacles able to stop it.

Forgotten Realms

Halruaan Skyships are a magical wonder created by the Halruaan. Like any other useful object in Toril, despite their method of creation being now widely known, they don't actually have any effect on the world despite just being magic items any sufficiently powerful wizard could make and several governments are described as having commissioned.

Mystara

Long before the Forgotten Realms, Mystara was crawling with flying ships of various makes, models and origins, mostly connected to the various magocracies of Mystara, such as Glantri and Alphatia. The most prominent user of airships is the Kingdom of Floating Ar, a magocracy who happen to live entirely on a nation made up of earthmotes. The airship Princess Ark was the center of The Voyage of the Princess Ark.

You can find a fanmade list of all the known airships mentioned in Mystara products here.

Pathfinder

Airships are given stats in Ultimate Combat. They’re essentially a giant hot air balloon, that’s lighter than air via alchemy, with a wooden platform attached under it and propelled by an unspecified but large magic device. They can carry 30 tons of cargo (compare to the 50 tons of a viking style longship and 150 of a proper sailing ship).

Airships would later appear in one module set in Alkenstar (a land where magic is fucked up and technology is higher to compensate), but their existence there is pure window dressing and only serves to describe how the PCs get from point a to b with no encounters and gives no details on them, though the presence of dedicated docks for them indicates they’re at least reasonably known within the country itself. The setting already established that Alkenstar is very jealous of its guns and its agents seek to destroy foundries elsewhere, so there’s at least an excuse for why these aren’t elsewhere.

An airship tileset has been released, based on the description from Ultimate Combat. The only official use of it has been some organized play scenarios set on the elemental plane of air, which imply the ships used are a different kind of vessel that only works on that plane.

Any item is capable of being made into an Animated Object if the creator is sufficiently powerful, and any animated object can have flight selected as an option. The potential to use this for an airship has not gone unnoticed by fans. Come second edition, a ship is outright the example given for a colossal animated object.

Spelljammer

Spelljammers are essentially high fantasy airships taken to the next level, as they're now capable of not only flying around in the atmosphere, but actually breaking orbit and flying between planets. Indeed, 'jammers are so much more powerful than standard D&D airships that their price-range is astronomical, and justifiably so. An AD&D splatbook for the Forgotten Realms, "Inside Ravens Bluff", has a pair of wizard brothers who own a major helm, which their father spent the vast majority of their inheritance on. For a major helm, even suborbital cargo runs would be a waste of potential... and what do these two geniuses do? They use "The Ravenstar" to haul a circus around a portion of one continent. Oh, and sometimes to go for moonlight cruises to impress the ladies. Anyone who knows the first thing about spelljamming who finds out about these two invariably goes something along the lines of "you fucking idiots!"