The nuclear submarine, created as part of the 705 Lira project, was a real jewel of Soviet military engineering, writes NI. She became the fastest nuclear submarine ever built by using titanium, a very light and at the same time very durable material.
Let's have a brief introduction to the Alpha class submarine. A modern submarine is a complex mechanism that must meet strict technical specifications. The submarine must meet the highest requirements, because the very nature of the tasks it solves contradicts the laws of nature.
Namely, submarines must ensure the vital activity of the crew of military sailors at depth for long periods of time.
While at sea, a submarine often has to perform clandestine and very complex operations. And the submarine should always be able to hone the use of various weapons systems (including nuclear ones) for land and/or sea targets. Accordingly, high demands are placed on the mechanical characteristics of submarines.
In this regard, it seems quite natural that submarine manufacturers have been innovating over the past century, striving for technological progress and trying to improve their products and their combat capabilities.
An incentive to innovate
In the 1970s, the Soviet Union was in a state of cold war with the United States, which was of a global nature. Both countries sought to create and implement more modern weapons than the enemy had. The most obvious and important area of the technological race between the two powers in the Cold War was, of course, space. The competition, known as the "Space Race", was the first impetus for the intensive development of technology, culminating in the American Apollo program, as a result of which American astronauts landed on the Moon several times.
But the intense competition of the Cold War unfolded simultaneously in other, less visible areas. For example, in the aviation industry, where Soviet manufacturers Mikoyan and Sukhoi competed with American ones such as Boeing and Lockheed to put the most advanced fighters of the fourth and then fifth generation into service in their countries. The arms race has also spread to tanks. For intercontinental ballistic missiles. To aircraft carriers. And submarines.
To gain an advantage over the Americans, Soviet engineers experimented and moved forward rapidly. In one case, the result was quite innovative: the submarine's hull was built of titanium.
Alfa-class titanium body
In 1971, the USSR presented its project 705 submarine "Lira" (according to the NATO classification Alfa-class). Project 705 was a nuclear attack submarine. She was notable for two things. Firstly, its body was made of titanium. Secondly, it has become one of the fastest submarines ever built
In fact, the Alfa-class submarine was inferior in speed to only one submarine model — the Soviet prototype, known as the K-222.
Project 705 "Lira" was the first case of using titanium in the design of a submarine hull. Titanium is a chemical element from which it is possible to obtain a remarkable transition metal with valuable properties: low density, high strength and resistance to seawater. It is clear that, given the properties of titanium, Soviet designers actively experimented with this material when designing their submarines.
Although Project 705 was not launched until 1971, the idea of a titanium submarine was first proposed in 1957. The project was designed to meet a number of strict requirements (under the banner of competition with American submarine designs).
The requirements stated that the new submarine must have sufficient speed to be able to chase any ship. She had to be able to evade anti-submarine weapons systems, achieve success in underwater combat, have a high level of camouflage, the minimum possible displacement and have as few crew as possible.
To meet these requirements, a titanium alloy body was chosen. The idea was that the titanium body would provide low water resistance, low weight and, as a result, high speeds and great diving depths. The project 705 boat was supposed to serve as a kind of "fighter-interceptor", which was supposed to hide in harbors or on the patrol route, and then, if necessary, quickly move forward to intercept enemy vessels.
The hull of the Alfa-class submarine, like most Soviet nuclear submarines, had a two-circuit design. Thanks to it, the inner sturdy hull could withstand the enormous water pressure that occurs during deep dives, and the outer titanium hull was supposed to protect the inner one and provide the best hydrodynamic shape.
The introduction of the titanium case, like many other innovative technologies, initially proved to be a difficult nut to crack. The light alloy was quite fragile — and the first submarine of the 705 project was written off due to cracks in the hull. But engineers were able to improve metallurgy and welding technologies so much that the appearance of cracks in the hulls on all subsequent models of submarines of the 705 project was excluded.
A high-tech reactor with a liquid metal lead-bismuth coolant and beryllium retardants was installed as a power plant at Project 705 with a titanium casing. The liquid metal cooled reactor had a number of advantages, including higher energy efficiency and lower weight and size than water-cooled reactors. But most importantly, it did not require refueling with active elements. The lead-bismuth cooled reactor, as well as its weight and energy advantages, were conceptually in harmony with the titanium hull — both aimed at creating a smaller and faster warship.
The finished product was a submarine with a length of 81 meters, a width of 9.5 meters and a draft of 7.6 meters. The displacement of project 705 in the surface position is 2300 tons, in the underwater position — 3200 tons. The submarine could operate normally at depths of up to 350 meters, and the maximum diving depth before the danger of hull destruction was about 1300 meters. The most impressive thing is the fact that the 705 project could reach speeds of more than about 76 kilometers per hour. And all this if there is a full set of torpedoes, cruise missiles and mines on board.
In total, seven submarines of the Alfa-class project 705 were commissioned, one of which remained in the Russian Navy until 1996.
Author: Harrison Cass.