Could airships make a comeback?
The airship could be set to quite literally make a big comeback. In 2013, the Aeros Corporation, based near San Diego, demonstrated a tethered flight of Dragon Dream - an airship measuring 90m (295ft) long and 27m wide.
As big as this airship is, it is still only small sized prototype - the final design could be more than 169m long and be able to carry a cargo of 66 tonnes.
BBC Click's Spencer Kelly finds out how the airship has the commercial potential of becoming a very efficient way of transporting heavy cargo.
- From the section Technology