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Two Variants of the LADA Class, One With a Main Motor Design from 1948; the Other Design from 1960

By Bruce Rule - Jan 15, 2016

As originally conceived, the Project 677 Russian diesel submarine came in at least two versions: (1) the Project 677 LADA with a surface displacement of 1450 tons. and (2) the larger Project 677E with a surface displacement of 1765 tons.

All Project 677 units were designed with a full diesel-electric propulsion system, i.e., two diesel-generators (ac to dc) powering a large shaft-mounted electric motor for submerged speeds up to 17 knots for the LADA and 21 knots for 677E units.

The LADA employs a 2700 hp PG-102M main propulsion motor. This is the same dc motor used to directly drive the centerline propulsion shaft of all ZULU, FOXTROT, GOLF and TANGO Class Soviet submarines. The PG-102 dates to at least 1948 when the design of the ZULU was completed by the Leningrad Development Office Number 16, five years before the first ZULU was commissioned. The letter “M” in the motor designation stands for modification. In this case, a “built-in-reducer.” a star-design planetary gear with an estimated ratio of 2.67 to one.

As previously discussed, the larger Project 677E employs a 5550 hp PG-141M main propulsion motor, also with a built-in-reducer with a ratio of about two-to-one. The PG-141 was first used with JULIETT Class Soviet SSGs designed about 1960 and first operational in 1963. The PG-141 was/is also employed by BRAVO, BELUGA INDIA, and KILO Class Soviet diesel submarines, and more recently by BOREY and YASEN Class Russian nuclear submarines.

This is yet another example – albeit an extreme one - of the Soviet/Russian axiom: “Better is the enemy of good enough,” e.g., the use of submarine main propulsion dc motor designs even if they are 56 to 68 years old.

See the linked site for discussions of the troubled development history of the LADA; however, if interested, quickly copy the text before the link is lost to an admonition to subscribe to the posting entity.