View source for U-1 (semi-trailer)

[[File:The U-1 and U-2 liquid hydrogen semi-trailer.jpg|thumb|The first trailers for transporting liquid hydrogen for aeronautics research.]]
The ''' U-1''' was a 1950s [[liquid hydrogen trailer]] designed to carry [[cryogenic]] [[liquid hydrogen]] (LH<sub>2</sub>) on roads being [[Towing|pulled]] by a powered vehicle. It was designed in response to requirements of the secret US government program code-named ''[[Lockheed CL-400 Suntan|Suntan]]'', which aimed to develop a high speed, high altitude hydrogen-powered military aircraft.<ref>{{cite web|last1=Sloop|first1=John L|title=Liquid hydrogen as a propulsion fuel, 1945-1959|url=https://history.nasa.gov/SP-4404/ch8-11.htm|website=NASA History Program|publisher=National Aeronautics and Space Administration|accessdate=April 22, 2016}}</ref> The trailer was constructed by the Cambridge Corporation and had a capacity of 26,500 liters with a [[hydrogen]] loss rate of approximately 2 percent per day.
The very low density of hydrogen made tandem axles on the semi-trailer unnecessary, so the U-1 had only one. During subsequent use of this equipment, there occurred an endless series of problems, all stemming from the single axle, which was unheard of for such a large trailer. It seems that each time one of these large semi-trailers went through a state weighing station, it roused suspicion, doubt about the equipment, and inquiries about the nature of the load.
Because of these difficulties, the specifications for its successor the U-2 was a double axle semi-trailer which was not needed for the load, but which raised no questions on the road.
==See also==
*[[Hydrogen economy]]
*[[Hydrogen infrastructure]]
*[[Timeline of hydrogen technologies]]
==References==
{{reflist}}
[[Category:Trailers]]
[[Category:Hydrogen technologies]]
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