Editing Zeppelin (section)

==Principal characteristics==
[[File:Zeppelin-LZ-127 internal and gas cells.svg|thumb|upright=1.5|right|The pink ovals depict [[hydrogen]] cells inside the [[LZ 127 Graf Zeppelin|LZ 127]], the magenta elements are ''[[Blaugas]]'' cells. The full-resolution picture labels more internals.]]

The principal feature of the Zeppelin's design was a fabric-covered, rigid metal framework of transverse rings and longitudinal girders enclosing a number of individual gasbags. This allowed the craft to be much larger than [[non-rigid airship]]s, which relied on the inflation of a single-pressure envelope to maintain their shape. The framework of most Zeppelins was made of [[duralumin]], a combination of [[aluminium]], [[copper]], and two or three other metals, the exact composition of which was kept secret for years. Early Zeppelins used rubberized cotton for the gasbags, but most later craft used [[goldbeater's skin]] made from cattle gut.<ref>{{cite magazine |url=https://www.newyorker.com/magazine/2016/02/29/a-new-generation-of-airships-is-born |title=A New Generation of Airships Is Born |magazine=[[The New Yorker]]}}</ref>

The first Zeppelins had long cylindrical hulls with tapered ends and complex multi-plane [[fin]]s. During World War&nbsp;I, following the lead of the rival firm [[Schütte-Lanz]] Luftschiffbau, almost all later airships changed to the more familiar streamlined shape with [[cruciform]] tail fins.

Zeppelins were propelled by several internal combustion [[internal combustion engine|engines]], mounted in [[airship#Gondola|gondolas]] or engine cars attached outside the structural framework. Some of these could provide reverse thrust for manoeuvring while mooring.

Early models had a fairly small externally-mounted gondola for passengers and crew beneath the frame. This space was never heated, because fire outside of the kitchen was considered too risky, and during trips across the North Atlantic or Siberia passengers were forced to bundle in blankets and furs to keep warm and were often miserably cold.

By the time of the ''[[Hindenburg-class airship|Hindenburg]]'' several important changes had made traveling much more comfortable: the passenger space had been relocated to the interior of the framework, passenger rooms were insulated from the exterior by the dining area, and forced-warm air could be circulated from the water that cooled the forward engines. The new design did prevent passengers from enjoying the views from the windows of their berths, which had been a major attraction on the ''Graf Zeppelin''. On both the older and newer vessels, the external viewing windows were often open during flight. The flight altitude was so low that no pressurization of the cabins was necessary. The ''Hindenburg'' did maintain a pressurized air-locked smoking room: no flame was allowed, but a single electric lighter was provided, which could not be removed from the room.<ref>{{cite web |url=http://www.airships.net/hindenburg/interiors |title=The Hindenburg's Interior: Passenger Decks |last=Grossman |first=Dan |date=2009 |publisher=Airships.net}}</ref>

Access to Zeppelins was achieved in a number of ways. The ''Graf Zeppelin''{{'}}s gondola was accessed while the vessel was on the ground, via gangways. The ''Hindenburg'' also had passenger gangways leading from the ground directly into its hull which could be withdrawn entirely, ground access to the gondola, and an exterior access hatch via its electrical room; this latter was intended for crew use only.

On some long-distance zeppelins, engines were powered by a special [[Blau gas]] produced by the Zeppelin facility in Friedrichshafen. The combustible Blau gas was formulated to make its weight near that of air, so that its storage and consumption had little effect on the zeppelin's [[Buoyancy compensator (aviation)|buoyancy]]. Blau gas was used on the first zeppelin voyage to America, starting in 1929.<ref name="Zeppelin">{{cite book |last1=Syon |first1=Guillaume de |title=Zeppelin!: Germany and the Airship, 1900–1939 |date=2007 |publisher=JHU Press |isbn=9780801886348 |page=130 |url=https://books.google.com/books?id=T-NBzwJgbn8C&pg=PA130 |language=en}}</ref>