Some messages between me and jailgurdnegative that I think explains airships fairly well in the Unus Solum universe.

Altitude:
Lighter ships can basically reach the edge of the atmosphere if given several hours and enough black rock powder. But they usually stay below 60 000 feet. Heavier ships like airforts' can get up to 25-30 000 feet depending on age. Newer ones can go higher obviously. But most battles take place far lower.

Classes:
Airfortress, heavy amour and heavy guns with a long countervail period. They are the pride of a fleet and a country and can cause the armies of weaker nations to surrender by simply arriving. The destruction of an airfortress, especially a new one, is a significant blow to national prestige. Their are some reservations about deploying them just anywhere because of that, and the fact that even the richest of nations can only field a handful.

Aircuirassier: Same as airfortress but with lighter armour. Along with airfrigates they compose the majority of any airnavy. Unlike airforts, they don't carry the same prestige and are a more affordable alternative. In a fight though, many and aircuirassier captain has wished they had that extra armour.

Airfrigate: Usually used to escort heavier class ships. They usually just have a lot of quick firing guns to target parasites and strengthen countervails. Although, when fighting weaker nations the quick firing guns are replaced with mediums so that they can provide fire support when it is too expensive to send out a fleet of airforts. They usually have 4 heavy canons on a similar caliber to that on airforts, but Corinth flies heavier ones with more guns.

Aircorvette: Fast and light scouts, usually used to designate targets for airforts, deploy Airmarines, provide close air support, save downed crew and act as a transport between ships in a fleet.  The weapons and amour used is really a mixed bag because captians can pretty much modify them with whatever they can afford.

Airschooner: Civilian ships converted for military use. They are very fast and have no permanent armament (usually the crew will bring a few MG's that they can mount on the guard rails). The only real use for them is carrying around VIP's, deploying spies or dropping in airmarines when a corvette isn't around. They were popular among pirates until the air navies became so powerful and quick to react that piracy became suicidal.

Sensors and such have a huge discrepancy depending on country. Arcea is in the 60's when it comes to computer ability, which is about 30-40 years ahead of the game. Their main guns are almost pinpoint accurate up to 38 km. Mediums are accurate up to 15km with quick firing guns accurate at 10km. Corinth is accurate up to 25km but gunners have to adjust for weather manually, their secondary are the same as Arcea's. North Gurrkha still has manual aiming, so accuracy depends highly on the crew. South Arcea is accurate up to 35km on main guns, 15 on mediums and 10 on quick firing. Enshaw is the same as Corinth. As far as sensors, Arcean's sensors can detect objects in the air 450 km away, but no other country is even close. Second place South Arcea's best radar's can reach 200 km, Corinth in third with 98km. 80-90km is about average.

To put this in perspective, an Arcean Airfortress can probably beat any other Airfortress within 5-10 minutes, (the time it takes to fire 4 to 7 volleys), much less anything lighter. A Corinthian one is going to take a half hour to hit, much less destroy one.

NOTE:

Ever wonder why their are all of those little flak bursts around an airship? Surely they don't intend to take down airships with those little shells! If that was your response, then you are correct. Those little flak bursts are called "counterveiling" (on a very small level in these cases). A counterveil occurs when a fleet or squadron fires off all of their guns simultaneously using short range flak shell. This creates a screen of hot metal that can stay in the air for up to 30 seconds. In recent years, flares and chaff have been added to the mixture, as well as smoke that can be produced by an airships engines to help hide the airship from both eyes and radars.