Fixed-wing aircraft on Refuge haven't progressed much beyond simple gliders. Lighter-than-air aircraft are another story though. From zeppelins to hot-air balloons, everyone knows that lighter-than-air aircraft are the future, and that heavier-than-air aircraft are a dead-end. At most they're a curiosity, to be used by tinkers and air show performers.
Because of the flammable nature of the various lifting gasses airships use, almost everyone uses cold steel aboard an airship. Throwing knives, swordplay, anything that won't make lots of sparks, really, is a good choice for fighting in the air. Combat aboard airships has one unbreakable rule: any man that uses a powder or cartridge weapon in the skies is an outcast among everyone that has any business in the air, pirate, privateer, and civilian alike. That's not to say that an enterprising pirate shouldn't know how to use them, though. People on the dirt have no such restrictions, and are quite willing to use a gun in a fight. Furthermore, pnumatic weapons have been developed specifically for the purpose of providing firepower minus the fire.
Airships represent the pinnacle of native technology on Refuge. Most modern airships use kerosine-powered Stirling engines (also called hot-air engines) to turn their propellers. Ballast in the newer models is handled by using anhydrous ammonia refridgeration to condense water from the air, and then either draining or condensing water as required to fall or rise. The only disadvantage to both these methods are that they're somewhat on the slow side. A Stirling engine requires a warm-up period before it runs at speed, and the amount of time it takes to condense water from the air is entirely dependent on how much moisture the air holds.
In older models, coal burning steam engines are common. With the proper precautions (extra-fine spark-catchers, thickened envelopes, and properly accounting for the wind) a coal-burner is mostly safe. A steam-engine can be brought to-speed in a third of the amount of time that a similarly sized Stirling engine takes. Older airships usually either simply vent gas to descend (expensive), or drop sand ballast brought aboard for the purpose of being ballast (also expensive).
Experimental steam-lifters use steam injected into the flight envelope to generate lift. They use the inside of the lifting envelope as a giant condenser, recycling the water that rolls down the insides of the envelope back into the steam boiler. The mechanical energy derived from the steam is used in the propellers. Steam-lifters cannot lift as much as their similarly sized gas-borne cousins.
Helium airships are also in the experimental stage. Helium is very costly to manufacture, and so far the only country that bothers is Texas.
Navigating the skies is tricky business. Magnetic compasses don't work, and while the Sky Lines provide a pair of reference points, they're not always visible. Because of this, piloting has become something of an art form. No pilot will be found without his rutter, a journal of conditions that are to be expected on a trade route or other previously-plotted course. Rutters are expensive to buy, and usually aren't for sale at all: a good rutter for normal-speed trade lanes will cost anywhere from $500 to $1000, depending on how much the person you're buying it from likes you. A rutter for a secret (and potentially profitable) route costs as much as the person who has it cares to ask. Most rutters are inherited or passed down from master to apprentice.