Comparison between an Airship and a Hot Air Balloon

Comparison between an Airship and a Hot Air Balloon

An airship, also known as a dirigible, is a powered lighter-than-air craft. In other words, an airship is an aircraft that derives its lift from a lifting gas (usually helium or hot air) while it is propelled forward by an engine. There are four (4) categories of airships: Rigid, Semi-Rigid, Non-Rigid and Hot Air Airships.

1.1        Rigid Airships

As their name implies, rigid airships have an internal frame. The Zeppelins and the USS Akron and Macon were famous rigid airships. The rigid structure, traditionally an aluminum alloy, holds up the form of the airship. In general rigid airships are only efficient when longer than 120 Meters (360ft.) because a good weight to volume ratio is (or was) only achievable for large airships. For a small airship the solid frame would have been too heavy. There is hope that the use of composite materials will change this.

1.2        Semi-Rigid Airships

Semi-rigid airships were more poplular earlier this century. They usually comprise a rigid lower keel construction and a pressurized envelope above that. The rigid keel can be attached directly to the envelope or hung underneath it. The airships of Brazilian aeronaut Alberto Santos-Dumont were semi-rigids. One of the most famous representants of the type wasItalia, the airship which General Umberto Nobile used on his attempt to reach the North Pole.

1.3        Non-Rigid Airships or Blimps 

Non-rigid airships, also known as Blimps, are the most common form nowadays. They are basically large gas balloons. Their shape is maintained by their internal overpressure. The only solid parts are the passenger car and the tail fins. All the airships currently flying for publicity use are of that type; the Goodyear Blimps, the Budweiser and the Metlife Blimps in the USA, and the Fuji Blimp in Europe.

1.4        Hot Air Airships

Hot air airships, also known as thermal airships, are counted as a fourth kind even though they are technically part of the non-rigid category. Hot air airships are derived from traditional hot air balloons. Early models were almost like balloons with an engine and tail fins added. Pretty soon envelopes were lengthened and the tail-fins and rudder were pressurized by air from the wash of the propeller. Newer hot air airships maintain their shape with internal overpressure in the whole envelope, a feature which older models did not have.



A hot air balloon is powerless, relying on the winds for locomotion, while an airship has a motor, allowing it to drift with its own power. A hot air balloon is just an “envelope” (the balloon part) that is capable of containing hot air, a burner, and a basket. Unlike blimps or dirigibles, hot air balloons do not need specific gases, such as helium, to fly. They operate on the simple principle that hot air is lighter than colder air. However, hot air balloons cannot be steered, and they rely on wind to move them along.