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Useful information on TYPHOON Class Russian SSBN propellers from the Internet.

By Bruce Rule - Feb 6, 2014

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( shows a remarkable photo of the stern configuration of a TYPHOON with shrouded, 7-bladed propellers.

( and ( show TYPHOON propellers that clearly have different projected area ratios (defined as the projected outline of the propeller divided by the subtended disc area) than the propellers shown by (

This is a significant difference that indicates the then-Soviet propeller designers had problems with whichever design was their original effort. Since the TYPHOON propellers with the smaller projected area ratio (blades covers less of the disc area) more closely resemble propellers used by later constructed DELTA IV units, I vote for the larger projected area ratio TYPHOON propellers as a failed design that reduced the maximum submerged speed of the TYPHOON from the original estimated 27 knots to 24-25 knots. In terms of shaft horsepower (a total of 100,000 based on the use of two OK-650 pressurized-water nuclear reactors (190 MW: 254,800 hp) each (published Russian data), this appears to have been a major design error that essentially "wasted" almost 50,000 shaft horsepower.

Also note that the total hp from two 190 MW nuclear reactors (509,600 hp) that deliver 100,000 shaft hp plus the estimated use of a total of four SSTGs (two in each of the twin main pressure hull operated in phase) that develop an estimated total of 16,000 hp provides a total maximum delivered hp of 116,000 for a 23-percent efficiency, a representative value for pressurized water nuclear reactors (PWRs) designed in the 1970s for use in both TYPHOON and OSCAR Class submarines.

The loss of 77-percent of the theoretical hp developed by two OK-650 PWRs occurs primarily in the heat-exchangers. If designers wanted to take the enormous risk of powering the main propulsion turbines with steam from the primary loop rather than from the radioactively isolated secondary loop, overall efficiencies as high as about 40-percent could be achieved.