Schienenzeppelin By Franz Kruckenberg, Germany

Criticism
The failure of Schienenzeppelin has been attributed to everything from the dangers of using an open propeller in crowded railway stations to fierce competition between Kruckenberg's company and the Deutsche Reichsbahn's separate efforts to build highspeed railcars.
One disadvantage of the rail zeppelin was the inherent difficulty of pulling additional wagons to form a train, because of its construction. Furthermore, the train could not use its propeller to climb steep gradients, as the flow would separate when full power was applied. Thus an additional means of propulsion was needed for such circumstances.