How do ships work?

Answer 1

Air ships work partly like a balloon, partly like a ship.

They get lift from being filled with a gas that's lighter than air, and they get propulsion from engines and propellers, that push them through the air.

Well, it depends on the airship. The mechanics behind various airship designs are usually quite different from one another, but they all operate under the same basic principles. For a flying machine to be defined as an airship, it must attain lift through some means of lighter-than-air buoyancy, and it must be steerable.

Most airships use lighter-than-air gasses such as hydrogen or helium to generate the lift they require to fly. To understand why these lighter gasses allow the airship to fly, picture a boat on the ocean. When the boat has air in it, which is lighter than water, it will float; but if the hull is breached, water will flood in and the boat will sink. The same is true of an airship; that is, the like the ships of the sea, airships float on air because they weigh less than air.

Airships, unlike some of their other lighter-than-air counterparts (Such as hot air balloons), don't rely on natural air currents to move, and they can be steered. Airships generally have one or more engines which push it forward (Or in some designs, pull it forward), usually via a propeller. They also tend to have rudders which allow them to steer by directing the flow of air, similar to those used on the wings and tail of an airplane.
Airships (no longer used) worked by filling a large central hull with helium or hydrogen and using motors to propel the craft. The gas renders the craft lighter-than-air, allowing it to float, and giving it lift. Gas is jettisoned to descend, and ballast (weight) is dumped to rise. A little power goes a long way, allowing the craft to drift.