Editing Magnetohydrodynamic drive (section)

===Marine propulsion===
[[File:Magnetohydrodynamic drive tube.jpg|thumb|A view through a tube in the thruster of ''Yamato I,'' at the Ship Science Museum in Tokyo. The electrode plates are visible top and bottom.]]
[[File:Magnetohydrodynamic drive.jpg|thumb|A view of the end of the thruster unit from ''Yamato I,'' at the Ship Science Museum in Tokyo]]
MHD has no moving parts, which means that a good design might be silent, reliable, and efficient. Additionally, the MHD design eliminates many of the wear and friction pieces of the [[Powertrain|drivetrain]] with a directly driven [[propeller]] by an engine. Problems with current technologies include expense and slow speed compared to a propeller driven by an engine.<ref name="PLOS" /><ref name="TPT" /> The extra expense is from the large generator that must be driven by an engine. Such a large generator is not required when an engine directly drives a propeller.

The first prototype, a 3-meter (10-feet) long submarine called EMS-1, was designed and tested in 1966 by Stewart Way, a professor of mechanical engineering at the [[University of California, Santa Barbara]]. Way, on leave from his job at [[Westinghouse Electric (1886)|Westinghouse Electric]], assigned his senior year undergraduate students to build the operational unit. This MHD submarine operated on batteries delivering power to electrodes and electromagnets, which produced a magnetic field of 0.015 tesla. The cruise speed was about 0.4 meter per second (15 inches per second) during the test in the bay of [[Santa Barbara, California]], in accordance with theoretical predictions.<ref>{{cite magazine |title=Run Silent, Run Electromagnetic |date=1966-09-23 |magazine=[[Time (magazine)|Time]] |url=http://www.time.com/time/magazine/article/0,9171,842848-1,00.html|archive-url=https://web.archive.org/web/20090114084102/http://www.time.com/time/magazine/article/0,9171,842848-1,00.html|url-status=dead|archive-date=January 14, 2009}}</ref><ref name="EMS-1 video">{{YouTube|id= RNMxlEfwdEc|title="EMS-1 electromagnetic submarine on US television (1966)"}}</ref><ref name="Way 1967b">{{cite conference |last1=Way |first1=S. |last2=Devlin |first2=C. |date=July 1967 |title=Prospects for the Electromagnetic Submarine |conference=AIAA 3rd Propulsion Joint Specialist Conference |location=Washington, D.C. |book-title=Paper 67-432}}</ref><ref name="Way 1968" />

Later, a Japanese prototype, the 3.6-meter long "ST-500", achieved speeds of up to 0.6&nbsp;m/s in 1979.<ref name="ICEC">A. Iwata, Y. Saji and S. Sato, "Construction of Model Ship ST-500 with Superconducting Electromagnetic Thrust System", in Proceedings of the 8th International Cryogenic Engineering Conference (ICEC 8), edited by C. Rizzuto (IPC Science and Technology, 1980), pp. 775–784.</ref>

In 1991, the world's first full-size prototype ''[[Yamato 1]]'' was completed in [[Japan]] after six years of [[research and development]] (R&D) by the [[Ship & Ocean Foundation]] (later known as the [[Ocean Policy Research Foundation]]). The ship successfully carried a crew of ten plus passengers at speeds of up to {{convert|15|km/h|knot|abbr=on}} in [[Kobe]] Harbour in June 1992.<ref name="PopSci 1992" /><ref name="BMESJ">{{cite journal
 |last1=Takezawa
 |first1=Setsuo
 |last2=Tamama
 |first2=Hiroshi
 |last3=Sugawawa
 |first3=Kazumi
 |last4=Sakai
 |first4=Hiroshi
 |last5=Matsuyama
 |first5=Chiaki
 |last6=Morita
 |first6=Hiroaki
 |last7=Suzuki
 |first7=Hiromi
 |last8=Ueyama
 |first8=Yoshihiro
 |title=Operation of the thruster for superconducting electromagnetohydrodynamic propulsion ship YAMATO-1
 |date=March 1995
 |journal=Bulletin of Marine Engineering Society of Japan
 |volume=23
 |issue=1
 |pages=46–55
 |url=http://www.jime.jp/e/publication/bulletin/english/pdf/mv23n011995p46.pdf
 |url-status=dead
 |archive-url=https://web.archive.org/web/20171215134832/http://www.jime.jp/e/publication/bulletin/english/pdf/mv23n011995p46.pdf
 |archive-date=2017-12-15
 |access-date=2018-04-04
 }}</ref>

Small-scale ship models were later built and studied extensively in the laboratory, leading to successful comparisons between the measurements and the theoretical prediction of ship terminal speeds.<ref name="PLOS" /><ref name="TPT" />

Military research about underwater MHD propulsion included high-speed [[torpedo]]es, [[remotely operated underwater vehicle]]s (ROV), [[autonomous underwater vehicle]]s (AUV), up to larger ones such as [[submarine]]s.<ref name="Lin 1990">{{cite report
 |last1=Lin |first1=T. F.
 |last2=Gilbert |first2=J. B
 |last3=Kossowsky |first3=R.
 |title=Sea-water magnetohydrodynamic propulsion for next-generation undersea vehicles
 |date=February 1990
 |publisher=Applied Research Laboratory, Pennsylvania State University
 |s2cid=35847351
 |id=US Navy/ONR Annual Report AD-A218 318
 |url=https://pdfs.semanticscholar.org/5e62/d4db0b04b871207f2dfab7102a19ad649c75.pdf |archive-url=https://web.archive.org/web/20180405152902/https://pdfs.semanticscholar.org/5e62/d4db0b04b871207f2dfab7102a19ad649c75.pdf |url-status=dead |archive-date=2018-04-05 |access-date=2018-04-04
}}</ref>