Actually Rap no American rigid airship ever used hydrogen except the Los Angeles and that was only before she was turned over to the US Navy by the German builders.
There were only 4 Rigids ever in service in the United States. The first one built here and to a German design was the Shenandoah. She shared hangar space at Lakehurst as well as helium with the Los Angeles. There actually was not enough helium in existence (and it was very costly as well) to fill the two giant airships so they swapped airtime and down time until the beautiful Shenandoah was lost in a storm over eastern Ohio.
Two more Rigids were built here in the states and were built at the Goodyear Airdock in Akron. The Akron and the Macon both had relatively short operational lives suffering crashes pretty early in their operations. The Los Angeles was quite successful but in the late 30's was decommisioned and scrapped.
I wish we had one around today as we do old planes of the era. The big rigids must have been truly a sight to behold. Think about the Goodyear blimp. It looks so big and yet it would require 2 and half of them, two football fields plus endzones to equal one rigid........They were far sleeker and at around 700 feet they were simply majestic.
They were also thought to be the technical wonders of the times and yet were obsolete before they flew. The storm in which the Shenandoah wrecked was a thunderstorm with wind shear and microburst patterns but no one at the time knew what that was. She was so huge that she was in two shears at the same time. It twisted apart and crashed in three pieces a few miles apart.
I rarely wish for things as I believe I have lived in the most interesting of times but I would love to been around in the days of rigid airship. So I amuse myself as a Shenandoah junkie and have visited the three wreck sites on numerous occasions. I also have about two feet of books on her and the Rigids around the world. Nice to see the rigid idea return but they aren't the Los Angeles, Akron, Macon or Shenandoah