While types of dirigibles include blimps and either rigid or semi-rigid airships, certain elements are common to all lighter-than-air vehicles. All dirigibles use some form of lighter-than-air gas to achieve lift. All dirigibles feature engines for power and steering mechanisms to control flight path. Likewise, all dirigibles have gondolas in which to transport people or cargo. The outer cloth skin of a dirigible holds the gases required to raise the engine, gondola and other components into the air.
The famous Goodyear dirigible, commonly seen flying over sporting events, is an example of a blimp. Blimps are a type of dirigible with no internal framework to support its outer skin and maintain the shape of the ship. In many aspects, blimps are close in concept to a hot-air balloon. As gas is released, the outer skin inflates, giving the blimp its distinct oval shape. Remove the gas, and the blimp deflates, much like a hot-air balloon. Unlike a hot-air balloon, a blimp features flaps and rudders to allow for steering capabilities. Also unlike a hot-air balloon, a blimp uses lighter-than-air gas to affect proper air pressure for flight.
The Farmers Insurance airship is commonly called a blimp, but is actually a semi-rigid Zeppelin NT. Semi-rigid airships are similar to blimps, in that such ships use air pressure and gas cells or bags to inflate the outer skin of the ship. Unlike blimps, semi-rigid airships have limited support framing inside the skin. Typically, the framing forms a keel just over the area where the gondola is attached. The keel is used to support and balance additional weight capacities. In flight, the partially framed keel also provides structural support needed for increased maneuverability. Other semi-rigid designs feature a small framework inside the balloon, which supports an enclosed gas bag envelope.
The Hindenburg, best known for its explosive demise in 1937, was a rigid airship known as a Zeppelin. Several organizations produce rigid airships, including, at one time, the U.S. Navy. Rigid airships have a large internal framework that supports the shape of the outer skin, with or without gases inside. Gas cells or bags within the framework provide the lighter-than-air lift needed. Deflated, a rigid airship maintains its elongated oval shape. Zeppelins are a specific type or brand of rigid airship designed by the Luftschiffbau Zeppelin, a company founded in Germany by Count Ferdinand von Zeppelin.
