Iron Shipwrights USS Seawolf SSN-575

[TomDougherty]

New kit prototype build of test shot-resin & 3-D printing

USS Seawolf SSN 575, the US second nuclear submarine was built alongside of the first SSN, USS Nautilus in Electric Boat’s South Shipyard.  Although built roughly at the same time, several external differences were apparent.  The BQR-4A bow sonar in the lower bow of Nautilus, was moved to the upper bow on Seawolf.  The sonar “windows” were initially individual rubber coating backed by thin steel (later replaced by a single, curved fiberglass window).  The “step sail” similar to the contemporary “Guppy” conversion fleet submarines, allowed the fitting of a small, pressure cylinder conning tower in the sail itself.  Moving the periscopes up allowed the submarine to be deeper in the water at periscope depth.  Also modified from Nautilus, although less visible, was the stern.  On Nautilus, the twin propellers were mounted directly on large, stern fins which fully enclosed the propeller shaft.  Seawolf instead had smaller fins and an exposed section of the propeller shaft, with a bearing housing and support struts for the screws (See Seawolf 575 stern at 1956 launch photo).  

However, the biggest difference between Nautilus and Seawolf was the reactor.  While Nautilus had the S2W (STR) pressurized water reactor, Seawolf was launched with the S2G (SIR) liquid sodium reactor.  The sodium cooled, beryllium moderated reactor could operate at much higher temperatures and lower pressures than the S2W pressurized water reactor.  This offered the possibility of generating superheated “dry” steam at significantly higher temperatures and greater thermal efficiencies.  The sodium reactor pumps were electromagnetic, with no moving parts.  The steam generators had a system of tubes within tubes, with the liquid sodium, and intermediate tube with a sodium potassium mix, and the last tube having the secondary loop water to generate superheated steam.  The intermediate tubes kept the water and sodium from mixing, a highly undesirable event.  

In practice, however, the high temperature sodium proved highly corrosive to the stainless steel materials employed for the superheaters, and pinhole leaks in the heat exchanger forced the operation at reduced power and abandonment of the superheated steam loop.  She was limited to using lower temperature saturated steam.  Seawolf cruised for >20,000 nautical miles over 2 years with the liquid sodium reactor at 80% power.  In late 1958, Seawolf returned to Electric Boat and the sodium reactor replaced by an S2Wa pressurized water reactor virtually identical to Nautilus.  After operating in the 1960’s, Seawolf was converted to a NURO Special Projects platform with an extended hull plug (with special operations equipment) installed forward of the sail. 

The Model

The model represents Seawolf in the early 1960’s.  I was approached by Jon Warneke of Iron Shipwrights who was looking for candidate submarine models that had not yet been kitted in 1/350 scale.  Jon and I exchanged numerous back and forth design details, with detail input also from Jacob Gunnarson, Jim Margerum, Jim Christley and David Grogan.  The finished model shown in the photos is the prototype version that Jon sent me for assembly, which is all 3-D printed from his design files.  There are minor (but important) differences in the finished kit, most notably in the bow sonar panels, a subtle revision in the sail sections blending, sail running lights relocated and the aft deck details revised, all updated based on the latest information.  The final kit is a resin hull, generated from a 3-D masters rubber mold and all of the other model pieces are 9K 3-D prints.  Many of the parts are provided in multiples (masts, propellers, propeller shafts, etc.) so these delicate items can be successfully removed even when “disaster strikes” on some tries (been there, did that).  And then there is the “no questions asked” parts replacement policy at Iron Shipwrights.  Kit available from Iron Shipwrights starting October 1.

 

Seawolf launch photo of stern design, different from Nautilus.

 

Prototype test shots of the build of the Seawolf model in 1/350 scale

 

Edited October 12, 2023 by TomDougherty
clarity and corrections

[Jmarc]

LLLLLLLLLLLLLooking good and well done also ! what is the lengt in 1/350 ?

[TomDougherty]

As built, which is what this kit depicts, roughly around 11 inches long.  The Special Projects version with the added hull section was roughly 52 feet longer.

[Jmarc]

CCCCCCCool, I thanks for the extra info !..