Ces sous-marins soviétiques en titane détiennent un record de vitesse en plongée jamais dépassé, même par la Russie moderne

In 1970, a Soviet titanium sub hit 44.7 knots underwater — still the record 54 years later. They only built one. It screamed like a factory, its reactor couldn't be turned off, and it was ruinously expensive. Moscow eventually chose steel. Oh, and the USSR secretly sold the CIA titanium to build the SR-71.