Editing LZ 129 Hindenburg (section)

==Design and development==
{{Main|Hindenburg_class_airship#Design_and_development|l1=''Hindenburg''-class airship}}

The Zeppelin Company had proposed ''LZ 128'' in 1929, after the world flight of the LZ 127 [[LZ 127 Graf Zeppelin|''Graf Zeppelin'']]. This ship was to be approximately {{cvt|245|m}} long and carry {{convert|140000|m3}} of [[hydrogen]]. Ten [[MTU Friedrichshafen|Maybach]] engines were to power five tandem engine cars (a plan from 1930 showed only four). The disaster of the British airship ''R 101'' prompted the Zeppelin Company to reconsider the use of hydrogen, therefore scrapping the LZ 128 in favour of a new airship designed for [[helium]], the LZ 129. Initial plans projected the LZ 129 to have a length of {{Convert|248|m}}, but {{cvt|11|m}} was dropped from the tail in order to allow the ship to fit in [[Lakehurst Hangar No. 1]].<ref name=":0">{{Cite book|title=Zeppelin Hindenburg: An Illustrated History of LZ-129|last1=Grossman|first1=Dan|last2=Ganz|first2=Cheryl|last3=Russell|first3=Patrick|publisher=The History Press|year=2017|isbn=978-0750969956|pages=33}}</ref>

[[File:Bundesarchiv Bild 146-1986-127-05, Bau des Luftschiffs LZ 129 "Hindenburg".jpg|thumb|left|''Hindenburg'' under construction]]

Manufacturing of components began in 1931, but construction of the ''Hindenburg'' did not commence until March 1932. The delay was largely due to [[Daimler-Benz]] designing and refining the LOF-6 [[diesel engine|diesel]] engines to reduce weight while fulfilling the output requirements set by the Zeppelin Company.<ref name=":0" />

''Hindenburg'' had a [[duralumin]] structure, incorporating 15 [[Ferris wheel]]-like main ring [[Bulkhead (partition)|bulkheads]] along its length, with 16 [[cotton]] gas bags fitted between them. The bulkheads were braced to each other by longitudinal [[girder]]s placed around their circumferences. The airship's outer skin was of cotton [[Aircraft dope|doped]] with a mixture of reflective materials intended to protect the gas bags within from [[radiation]], both [[ultraviolet]] (which would damage them) and [[infrared]] (which might cause them to overheat). The gas cells were made by a new method pioneered by [[Goodyear Tire and Rubber Company|Goodyear]] using multiple layers of gelatinized [[latex]] rather than the previous [[goldbeater's skin]]s. In 1931 the Zeppelin Company purchased {{convert|5000|kg|lb|abbr=on}} of duralumin salvaged from the wreckage of the October 1930 crash of the British airship [[R101]].<ref>[http://www.aht.ndirect.co.uk/airships/r101/Crash/R101_Crash.htm "R101: the Final Trials and Loss of the Ship."] The Airship Heritage Trust. Retrieved October 27, 2010.</ref>

[[File:Bundesarchiv Bild 147-0640, Luftschiff Hindenburg (LZ-129), Speisesaal.jpg|thumb|right|Dining room]]
[[File:Bundesarchiv Bild 147-0639, Luftschiff Hindenburg (LZ-129), Gesellschaftsraum.jpg|thumb|right|Lounge, with the world map painted on the wall]]

''Hindenburg''{{'}}s  interior furnishings were designed by [[Fritz August Breuhaus]], whose design experience included [[Pullman Company|Pullman coaches]], [[ocean liner]]s, and [[warship]]s of the [[German Navy]].<ref name="breuhaus">Lehmann 1937, p. 319.</ref> The upper "A" Deck contained 25 small two-passenger cabins in the middle flanked by large public rooms: a dining room to [[Port and starboard|port]] and a lounge and writing room to [[Port and starboard|starboard]]. Paintings on the dining room walls portrayed the ''Graf Zeppelin''{{'}}s trips to [[South America]]. A stylized world map covered the wall of the lounge. Long slanted windows ran the length of both decks. The passengers were expected to spend most of their time in the public areas, rather than their cramped cabins.<ref name="public-areas">Dick and Robinson 1985, p. 96.</ref>

The lower "B" Deck contained washrooms, a [[mess hall]] for the crew, and a smoking lounge. [[Harold G. Dick]], an American representative from the Goodyear Zeppelin Company,<ref>[http://www.ohiohistorycentral.org/entry.php?rec=899 "The Goodyear Zeppelin Company."] ''Ohio History Central.'' Retrieved October 27, 2010.</ref> recalled  "The only entrance to the smoking room, which was pressurized to prevent the admission of any leaking hydrogen, was via the bar, which had a swiveling air lock door, and all departing passengers were scrutinized by the bar steward to make sure they were not carrying out a lit cigarette or pipe."<ref name="lounge">Dick and Robinson 1985, p. 97.</ref><ref>[https://books.google.com/books?id=uN4DAAAAMBAJ&pg=PA846 "LZ-129 The Latest Airship,"] ''Popular Mechanics'', June 1935.</ref>

===Use of hydrogen instead of helium===
[[Helium]] was initially selected for the lifting gas because it was the safest to use in airships, as it is not flammable.<ref name="Macgregor">MacGregor, Anne. "The Hindenburg Disaster: Probable Cause" (Documentary film). ''Moondance Films/Discovery Channel,'' Broadcast air date: 2001.</ref> One proposed measure to save helium was to make double-gas cells for 14 of the 16 gas cells; an inner hydrogen cell would be protected by an outer cell filled with helium,<ref name="Macgregor"/><ref>{{cite web|last1=Grossman|first1=Dan|title=Hindenburg Design and Technology|url=http://www.airships.net/hindenburg/design-technology|website=Airships.net|access-date=June 9, 2015}}</ref> with vertical ducting to the dorsal area of the envelope to permit separate filling and venting of the inner hydrogen cells. At the time, however, helium was also relatively rare and extremely expensive as the gas was available in industrial quantities only from distillation plants at certain [[oil field]]s in the United States. [[Hydrogen]], by comparison, could be cheaply produced by any industrialized nation and being lighter than helium also provided more lift. Because of its expense and rarity, American rigid airships using helium were forced to conserve the gas at all costs and this hampered their operation.<ref>Vaeth 2005, p. 38.</ref>

Despite a U.S. ban on the export of helium under the [[Helium Act of 1925|Helium Control Act of 1927]],{{sfn|Sears|2015|pages=108–113}} the Germans designed the airship to use the far safer gas in the belief that they could convince the U.S. government to license its export. When the designers learned that the National Munitions Control Board refused to lift the export ban, they were forced to re-engineer ''Hindenburg'' to use flammable hydrogen gas, which was the only alternative [[Lifting gas|lighter-than-air gas]] that could provide sufficient lift.<ref name="Macgregor"/> One of the side benefits of being forced to utilize the flammable yet lighter hydrogen was that more passenger cabins could be added.