The Tupolev Tu-155 is a modified Tu-154 (CCCP-85035) which was used as an alternative fuel testbed. This is the first experimental aircraft in the world operating on liquid hydrogen. The similar Tu-156 was never built.
The Tu-155 first flew on 15 April 1988. It used hydrogen as fuel, and, later liquified natural gas (LNG). It flew until the fall of the Soviet Union and it is currently stored in the Ramenskoye Airport near Zhukovskiy. The Tu-156 was intended to fly around 1997 but was cancelled also due to the fall of the Soviet Union. The aircraft used cryogenics to store fuel. The fuel tank was located in the air-blown (or nitrogen) rear compartment. A distinctive feature of the aircraft is that the protrusion of the ventilation system is visible on the tail (near the no.2 engine). The Tu-155 used the Kuznetsov NK-88 engines. The Tu-156 was intended to use the Kuznetsov NK-89 engines. It flew around 100 flights until it was placed in storage. During test flights 14 world records were established for hydrogen-powered aircraft.