Lift Cage

A lift cage, or lifting cage, is a device which utilizes magnetic levitation to create a lifting force, allowing airships to fly.

Function
Lift cages consist of a linked system of lift motors, each of which use low-temperature refrigeration to cool the mineral alicul below 2 degrees Celsius. When the alicul is cooled to such low temperatures, it reacts with the planet's strong magnetic field via the Meissner effect, creating an upward force.

Limitations

 * The weight of the low-temperature cooling unit versus the lifting force of a given unit puts a soft minimum size on how small a lift cage can get, and therefore how small a true airship can be. This limit has been slowly decreasing with time, with the current the smallest true airships having a volume of around 150 cubic meters.
 * Because the lift cage relies on repelling the planetary magnetic field, the units can only create a downward force, meaning that airships must use an alternative form of propulsion to travel, such as props, jet engines, or sails.
 * A consistent supply of electrical power is required for sustained flight, due to the active refridgeration requirement. If power to a lift cage is lost, the alicul will slowly began to heat up to the temperature of its surroundings, gradually decreasing lift. This typically means that airships which lose power tend to gradually sink towards the ground. However, if the alicul exheeds 30 degrees Celsius, it will lose its lifting properties entirely, causing a sudden crash.
 * Because they rely on repelling the planet's magnetic field, lift cages function optimally near the equatorial regions, with safe operation becoming impossible near the polar regions, due to the proximity to the magnetic poles. Any attempt to fly too close to the polar regions will result in the airship becoming dangerously bouyant and being thrown into the sky