667A YANKEE I

In 1958 OKB-18 started the development of a new ballistic missile submarine. Initially work was undertaken on two versions, of which only one was authorized. A.S. Kassatsiyer, the author of both versions was designated as chief designer. The development of the submarine faced significant problems regarding the launch system. During elimination of the problems the project underwent fundamental changes and as a result the completely new submarine design received the new designation 667A. The new chief designer was S. I. Kovalev. The revised 667A submarine was both developed and authorized in 1962.

The external contours of the submarine were designed to achieve minimal resistance when operating under water. Unlike previous submarines, the horizontal hydroplanes were arranged on the sail. The cylinder-shaped pressure hull is divided into 10 compartments and has an exterior diameter of 9.4m.

The SSBN 667A is equipped with the D-5 launch system and 16 R-27 missiles with a range of about 2400 km. They are arranged in two rows in the fourth and fifth compartments. The missiles can be launched from a depth of 40-50 meters below the surface, while the submarine is moving at a speed of up to 3-4 knots. The missiles are fired in four salvos each comprising four missiles. The time needed for pre-launch preparation is 8 minutes, and within a salvo the missiles are fired at intervals of 8 seconds. After each salvo the submarine needs three minutes return to the launching depth and between the second and third salvo it takes 20-35 minutes to pump water from the tanks into the launching tubes.

The primary propulsion machinery includes two self-contained units [port and starboard], each of which consists of a pressurized water reactor reactor, and an independent turbogear assembly. The maximum speed when submerged is 27 knots. The auxiliary propulsion motors can be used for torpedo firing, to maintain electric power during emergency and provide for stand-by capability of the boat while on the surface.

To reduce the noise of the submarine special propellers were created, the pressure hull was covered with sound-absorbing rubber and the external hull was covered with a antihydroacoustic coating. The footings under the main and auxiliary propulsion systems are also isolated by a layer of rubber.

The 667A SSBNs were equipped with the "Cloud" battle management system which could receive signals up to a depth of 50 meters with the help of the towed antenna "Paravan." The first four 667A Yankee submarines employed the "Sigma" navigation system whereas the follow-on ships were equipped with the "Tobol" -- the first Soviet navigational system that used a satellite navigation system. This system provided reliable navigation in the Arctic Region and in the Pacific Ocean and also sustained the operational capability of the missiles at high latitudes down to 85 degrees.

The first 667A Yankee submarine, with the tactical designation K-137, was launched in 1964 at the Northern machine-building enterprise in Severodvinsk. In July 1967 the submarine "K-137" completed sea trials and at the end of 1967 it was introduced into the Northern fleet. Between 1967 and 1974 a total of 34 strategic submarines of the 667A class were build. 24 submarines were launched in Severodvinsk and 10 in Komsomolsk na Amure.

In 1972-1983 the Yankee submarines along with older submarines were re-equipped with the D-5U launch system and R-27U missiles. The R-27U missile had a greater range -- up to 3000 km -- and carried multiple reentry vehicles. The upgraded submarine was designated as 667AU.

In 1967 the first 667A ballistic submarines to form part of the Northern fleet were incorporated into the 31st division of strategic submarines, which was based in the port of Sayda. At the end of the 60s the 19th division of strategic submarines was also equipped with 667A submarines. Both divisions formed part of a structure consisting of 12 squadrons, which in December 1969 was transformed into the 3rd flotilla of submarines.