Airships are aerospace vehicles that get most of their lifting capability from ‘static’ lift using gases which are lighter than air, unlike aircraft that fly using the principles of dynamic lift i.e. wings (fixed or rotary). In essence, much of the energy expended by a conventional aircraft is used to keep it in the air, while most of the energy used by an airship is to propel it forward. Airships were widely used in the first half of the 20th century, for a variety of purposes, but the speed, power and glamour of conventional aircraft eclipsed the benefits of LTA vehicles for many years.
However, the widespread concerns about climate change, the effects of economic and political turmoil on the price of petroleum and the need for security organisations to maintain persistent surveillance in a cost-effective manner, are causing a fundamental reassessment of the utility of Airships. A number of organisations are beginning to explore the use of LTA vehicles for different roles in today's society.
As well as traditional airship types, the last few years have seen some interest in exploring new concepts which combine static lift with an increased use of dynamic lift, using either airfoil or rotorcraft technology to increase their lifting capabilities. These hybrid systems have only recently reached the prototyping stage.