Titanium is the strongest and at the same time the most secret metal of the Navy. Two of our boats were made from its alloys, which have set unsurpassed world records so far, the underwater speed record, more than 82 kilometers per hour, and the diving depth record, 1027 meters. Nowadays, the fleet includes titanium “submarine fighters”, boats of two projects “Barracuda” and “Condor”. “Military Acceptance” has already talked about them. And now it’s time to recall two more titanium projects, these are the anti-sabotage Piranhas and the multi-purpose Lyra. “Lira” is one of the most mysterious boats of our fleet. Only officers were recruited into her crew, the selection went like a detachment of astronauts, and the most surprising thing is that they did not serve in the compartments, the boat was automated as much as possible. It is no coincidence that the Lyra were among the first boats, destroyed in the 90s at the request of the United States. However, the simulator miraculously survived, exactly repeating several compartments of the mysterious “Lyra” at once. “Military Acceptance” for the first time will show in detail this extremely complex structure from an engineering point of view and tell about all the unclassified properties of underwater titanium.