Tupolev Tu-155

The Tupolev Tu-155 was a modified Tupolev Tu-154 airliner used as an alternative-fuel testbed, and was the world's first experimental aircraft operating on hydrogen and later liquefied natural gas. It first flew on 15 April 1988, burning liquid hydrogen first and liquefied natural gas (LNG) later, and it carried its fuel as a cryogenic liquid. It was a hybrid: only one of its three Kuznetsov NK-8 engines, known as the NK-88 in this form, actually ran on the alternative fuel, and the tank sat in an air-blown rear compartment. The aircraft flew about 100 flights before it was placed in storage, only some of them on hydrogen, and from January 1989 Tupolev mainly tested natural gas as a substitute for kerosene. It flew until the end of the Soviet Union and is stored at Ramenskoye Airport near Zhukovskiy. A similar Tu-156 was never built.