The Russians appreciate the design advantages of pump jet propulsors. The same math and physics work in both the former east as well as the west. Pump jets are indeed heavier, but so much quieter. The big advantage pump jets offer is providing the submarine with a higher tactical ‘silent speed’. A conventional propeller submarine may have a silent speed of 7 to 9 knots, the pump jet submarine much higher – speculating in the ‘teen’ speeds or more. On the new American Seawolf, the British Trafalgar and Swifture SSN’s – the reactor power plant cooling circulation pumps, a potential source of radiated noise can be switched off. Water sea suction intakes in the leading edges of the horizontal sternplanes on the SSN’s then can provide cooling circulation by the forward motion of the vessel through the water.

Pump jets are very impractical on diesel conventional powered submarines. The added weight and cost is worthless if the batteries (or even present day fuel cells) of a conventional powered submarine cannot sustain those higher silent speeds a pump jet could exploit for very long. Nuclear power you can sustain those speeds for literally years. This is why you see pump jets only on nuclear powered combatants, and if ever on diesel submarines at all, it is for experimental tests of short duration runs only. Hence the Kilo test boat – 877V project design.

All pump jet submarines also have little reversing backing power astern too. Usually tugs for docking are manditory. But the operational advantages of the lamp shade on the stern seem to out weigh this.

The new generation Russian ballistic missile submarines of the Borei class (officially designated Project 935). Builders Models of these submarines show a Russian pump jet design. These new submarines have been named: Yury Dolgoruky, Alexander Nevsky, and Vladimir Monomakh. The Russian planned contingent is for 10 strategic submarines expected to be commissioned within the next decade (5 will be project 935, and 5 will be a more advanced project 955 in service by 2015.

Model of Yury Dolgorruky below.

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Woodie