Calling all USS Narwhal SSN-671 fans

[CC Clarke]

The term "Special Projects" is used pretty loosely. It was originally assigned to denote the Polaris program office under Raborn.

Any submarine can perform CNO-designated Special Projects. My first boat, a boomer was involved in one, and it was study performed by some scientists we had onboard for a few days.

Narwhal conducted many Special Projects due to her low acoustic signature. TB-29 testing was but one that has been acknowledged publicly. The array was much longer than a TB-16, and the pronounced hump on the stern likely housed the array and some of its handling equipment. It was assigned to an East coast DevRon.

The Ocean Engineering program was called CNO Special Projects on my transfer orders. I didn't have a clue as to what OE meant until after I checked in. All OE boats and other assigned assets on the West coast were assigned to COMSUBDEVGRUONE, based in San Diego. The MINSY platforms were assigned there because of the cleared shipyard work force and industrial and design capabilities MINSY offered. They pulled off some amazing feats that may someday be revealed.

Nautilus was a hit and I'm on the the next set of hulls.

[Tom Dougherty]

If you get a chance, post some photos of your Nautilus here. I would love to see it in 1/72! What new hulls are in progress? (Besides RBR, that is)

I just wrote a three part article for American Submariner magazine on the establishment of Raborn�s Special Projects office for Polaris. And that indeed was the first use of �Special Projects�. Most of the article (part 1 has published) concerns the challenges of building the Polaris system (submarine, missile navigation, guidance, etc.) employing mid-1950�s technology.

Special Projects is a broader term for sure, but Ocean Engineering, another term I have seen used is probably a bit more obscure, although for the kinds equipment and modifications carried out, more specific. Some under the NURO sponsorship .

Losing MINSY, as you have mentioned, was a big mistake. Now there is a shortage of Naval shipyards, and the expertise of Mare is long gone.

[Tom Dougherty]

USS Narwhal, SSN 671 prototype kit from Iron Shipwrights. The final kit will feature a resin hull and 3-D printed sail, planes, rudders, screw, and masts.

Narwhal Background:

The Navy challenged Electric Boat to build a quieter submarine. A unique design under project SCB 245, Narwhal was her own class. Forward of the reactor compartment she was broadly similar to the contemporary Sturgeon-class submarines, but with a slightly larger diameter to accommodate the natural circulation reactor setup.
Electric Boat identified reduced sound signature improvements. The first was the main reactor coolant pumps. These large, high-pressure pumps spin under heavy load and can be the most significant acoustic source of any nuclear-powered submarine.

General Electric designed Narwhal�s unique S5G power plant with the reactor vessel situated low in the submarine�s hull and the two steam generators situated above the reactor, cocked slightly to fit into the hull. This arrangement facilitated a natural flow of the reactor�s primary coolant. This pressurized-water reactor (PWR) design heated its primary loop in the reactor and convection moved the water into the steam generator near the top of the loop where energy is exchanged into the secondary loop system to generate steam for propulsion. After heat transfer, the primary coolant flows back down towards the reactor vessel in a return loop.

Both initial low power conditions as well as when high power for maximum speed require the reactor coolant pumps. However, there is a wide region of power between these two conditions that allow the main engines and turbines to run normally without the main reactor coolant pumps working.

To address acoustic noise from the standard propulsion turbines which required a large reduction gear system to slow the propeller to usable, efficient turns, a revolutionary, direct-drive main engine turbine that was mechanically linked to the shaft was installed. This system operated at a lower RPM and was larger than the original reduction gear design, 12 feet in diameter and 30 feet in length, resulting in a slightly wider submarine than the Sturgeon class design, on which Narwhal was based.

The main seawater intake system is used to cool and condense the steam from the drive turbines. Two seawater scoops were added to the stern planes that would force water into the main seawater system as the Narwhal moved forward. During low speed, slow approach operations these scoops moved enough water to cool the condenser loads. Also, new ship service turbine generators which operated at a lower RPM (quieter).

In a subsequent overhaul, sonar was upgraded to the AN/BQQ-5D spherical bow array system along with a long line TB-23 towed array was added on the starboard side, with a deploy tube on the upper stern plane.

The natural circulation reactor design was incorporated into the Ohio SSBN S8G design, as well as the Seawolf class S6W and the Virginia S9G reactors. Other aspects, such as the direct drive turbine were not repeated in subsequent classes. Also, the condenser cooling scoops violated SubSafe principles by having long internal piping runs under sea pressure, so short direct runs with pumps were employed.

[CC Clarke]

Nice job on a unique hull Tom!

[Nino]

Ditto! Beautiful work on a Sub with some rather "exotic improvements".

I hope we will get some posts regarding the Scoops. The ISW rendering looks very cool. ( Pun intended)

Nino.