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USS Tullibee SSKN


TomDougherty
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This is a model of USS Tullibee SSN 597, a 1960 attempt at a small nuclear powered hunter/killer submarine.  During the 1940-50's, an SSK program consisted of both converted WWII fleet submarines, which were equipped with a large BQR-4 bow sonar, as well as building small, diesel SSKs with a bow that had both the large BQR-4 and a smaller "chin" mounted BQR-2.  The goal was to have a "barrier" strategy and use the long range BQR-4 low frequency sonar to detect Soviet diesel submarines and hunt them in the event that a war in Europe broke out.  While the fleet boat SSK conversions worked reasonably well, the smaller SSKs (K1, K2, and K3) were found to be deficient in a number of areas, and only three built.  Most alarmingly, however was the arrival of nuclear powered submarines.  Nautilus (SSN 571) and Seawolf (SSN 575) quickly demonstrated the ability to move rapidly in three dimensions underwater, largely defeating the 1950 era sonar sets such as the BQR-4.

The solution was to equip submarines with a BQQ-2 sonar sphere, a large metal ball with multiple hydrophones (1200+) aimed in three dimensions.  To test this concept, a nuclear powered, small hunter killer was designed and that was Tullibee.  The hemispherical bow was given over to the BQQ-2 sonar sphere, with the torpedo room and torpedo tubes moved further aft and the tubes angled out at 10 degrees.  Also, the submarine was equipped with an early version of PUFFS fins.  The PUFFS was a passive fire control system that used time of arrival of sound along the baseline of the hull to generate a target bearing. The hull was long and narrow (273 feet X 23.7 feet) to place the bow sonar sphere as far away from the machinery spaces as possible.  Displacement was only 2300 tons surfaced, and test depth 700 feet.  Because the early nuclear submarines proved to have noisy steam propulsion plants with turbine and reduction gear noise, Tullibee employed quiet turboelectric drive.  A compact, 2500 shaft horsepower S2C nuclear reactor provided steam to drive electric turbogenerators.  The electrical power from these generators was then employed in a DC direct drive electric motor system coupled to the propeller shaft.  In service, Tullibee proved to be very quiet, albeit slow (16 knots top submerged speed).  Her turboelectric drive plant proved to be troublesome over time.  The decision was made not to have a separate hunter/killer SSKN and attack submarine SSN, but to combine the hunter/killer and attack missions in the Thresher/Permit class.  These submarines had sonar spheres, relocated torpedo tubes,  and were quieted by placing the steam turbines and gear machinery on sound isolation rafts, greatly reducing sound transmitted externally.  Thus Tullibee  ended up as a unique, one off experiment, and not the prototype for a fleet of SSKN hunters.

The model of Tullibee is the old 1/350 scale Yankee ModelWorks resin kit.  I pinned the various control surfaces to the hull with metal wire inserted into pre-drilled holes and fastened with cyanoacrylate glue.  The kit has a photo etch propeller, which I replace with one of Mike Fuller's superb 3-D printed propellers.  Early in her career, Tullibee  had a five bladed propeller and a small set of PUFFS fins on her upper hull.  There were three PUFFS installed, but the center fin is abaft the sail, beneath the aft turtleback.  These items were later replaced by a 7 blade J-propeller and a larger set of PUFFS fins. The resin kit did not have ballast tank openings, so I added a set of photo etch vents in the appropriate places.  After priming, Tullibee was finished in her "as launched" color scheme, with the rescue buoys still in orange.  It is a unique looking early nuclear submarine.  

 

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Edited by TomDougherty
details & spelling, and "helpful" erroneous corrections by spellcheck
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Beautiful work! I had never heard of this submarine or the history behind it. Than you as well for that education. This is why I love this hobby so much: not only do I learn about things I never knew, but I get to see a 3-D rendered model of those things.

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Thanks, Mark, for your comment.  The Navy tried one more DC turboelectric drive submarine, the modified Sturgeon class Glenard P. Lipscomb. It was very quiet, but again slow, like Tullibee.   DC does not scale well as power is increased.


However, the upcoming Columbia class SSBN class, the Ohio replacements, are currently planned to have AC turbo electric drive.  The AC electric motors will be more compact than the massive DC versions, and much quieter than steam turbines and gear trains currently in use.  At one point, later block versions of the Virginia  class were also planned to have turbo electric drive, but I think that was dropped.

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