How are airships controlled?

An airship pilot has three ways of adjusting lift: Every lighter-than-air vehicle needs some ballast to adjust its weight. This could be sand, but mostly water is used. A blimp is only partially filled with helium. The envelope is held taut by filling a bag inside with air, called a ballonet. read more

Obviously airships control their horizontal movement with both propellers and rudders, but assuming you're referring to how they control vertical movement, it's actually quite simple. The envelope (not sure if that's the right name for it) of the ship is filled with a gas that's lighter than air, allowing it to float. read more

Airships were the first aircraft capable of controlled powered flight, and were most commonly used before the 1940s, but their use decreased over time as their capabilities were surpassed by those of aeroplanes. read more

Click on the button to see how a blimp ascends and descends. A blimp or airship controls its buoyancy in the air much like a submarine does in the water. The ballonets act like ballast tanks holding "heavy" air. When the blimp takes off, the pilot vents air from the ballonets through the air valves. read more