The U.S. nuclear-propelled attack submarine Seawolf (SSN-21) underwent her initial sea trials this summer with great success. The Navy would not comment on whether the Seawolf attained her designed speed, but immediately after the trials the head of Navy nuclear propulsion declared, “Today the country has the fastest, the quietest, the most heavily armed submarine in the world.”1
The statement does raise the important question. How fast is fast? The Seawolf s designed underwater speed is 35 knots. The newest Russian attack submarines of the Akula (Project 885) series are credited publicly with a speed of 35 knots,2 as are four contemporary submarines of the Sierra class (Project 945). But Russian submarine designers have stated that the Akula is faster than 35 knots, and the U.S. intelligence community often has estimated Soviet submarine characteristics and capabilities incorrectly. For example, the first Soviet nuclear-propelled submarine, the November (Project 627A), surprised Western analysts when she reached a speed of almost 30 knots compared to a reported 23 knots for the first U.S. nuclear submarine, the Nautilus (SSN-571).3 (The Nautilus was completed in 1955; the first November went to sea in 1958.)
The world’s fastest submarine of the period, however, was not nuclear, but the diesel-electric research submarine Albacore (AGSS-569). Completed in 1953 as a test bed for the “teardrop” hull configuration and other advanced submarine features, the Albacore was refitted with silver-zinc batteries and a second electric motor to generate some 15,000 horsepower. In that configuration, she attained more than 35 knots submerged on several occasions.4
The Albacore could attain this speed for periods of about 15 minutes because of the limitations of her battery capacity. It would require nuclear propulsion to provide essentially unlimited high submerged speeds.5
The U.S. Navy gained underwater speed superiority in nuclear submarines in 1959 with completion of the Skipjack (SSN-585), which combined nuclear propulsion with the teardrop hull form to attain a speed of about 33 knots. The subsequent U.S. attack submarines of the Thresher (SSN-593) and Sturgeon (SSN-637) classes were larger, with more wetted surface and parallel amidships sections, but retained the same 15,000-horsepower S5W reactor plant of the Skipjack. U.S. attack submarine speeds thus declined in the 1960s and 1970s.
The U.S. Navy again was surprised when the first Soviet submarine of the Victor (Project 671) class went to sea in late 1967. Powered by a two-PWR plant generating much more than 30,000 horsepower, the Victor could attain 33 knots.
Admiral Hyman Rickover, then head of the U.S. nuclear propulsion program, already had initiated work on a more powerful submarine reactor plant than the S5W, which powered virtually all SSNs built from 1959 plus the Navy’s 41 strategic missile submarines (SSBNs). With the Victor SSN at sea, Rickover accelerated development of a more powerful plant, adopting the D2G used in surface ships for submarine use—the S6G reactor plant with approximately 30,000 horsepower. This plant provided the Los Angeles (SSN-688) with a speed of some 33 knots when she went to sea in late 1976—nine years after the first Victor.
Rickover strongly supported this belated increase in SSN speed:
With extra speed, a submarine captain has a far better chance of closing to within target range of every ship he detects so he can achieve the best position for attack. Speed enhances this ability to evade counterattacks, and to reattack the remaining units, even if they attempt to escape at high speed. With speed, a submarine captain is better able to position himself advantageously to provide maximum tactical advantage with respect to his target. He can better avoid detection and, if detected, he has a better chance of evading torpedoes and other antisubmarine weapons.6
Rickover also cited speed as essential to provide effective support for surface task forces, a role being advocated to justify the increase in speed in the Los Angeles class.
But faster Soviet submarines already were at sea. The first record-breaking Alfa (Project 705) attack submarine had gone to sea about 1972. Her two liquid-metal-cooled reactors produced a reported 47,000 horsepower—and innumerable problems. The lead submarine encountered major engineering problems and soon was scrapped.
The prototype Alfa was followed by six production submarines, completed from 1979 to 1983. These titanium-hull SSNs had a maximum speed of 42-43 knots and an operating depth of some 2,500 feet, both far in excess of U.S. submarines. Their operational success was limited, but as test beds for advanced concepts in hull design, automation, materials, and propulsion, they were invaluable.7
The little-known Papa (Project 661) cruise missile submarine K-162, which predated the Alfa, was an equally revolutionary submarine. The first submarine to have a titanium hull, she introduced new concepts in submarine weapons and sensors. At the time she was completed in 1971, the Papa was the largest nonstrategic missile submarine yet built by any navy, exceeding even the U.S. giant Triton (SSRN-586) and approaching the U.S. Polaris submarines in displacement.
Although not a deep-diving submarine, the K-162’s titanium hull improved her “unsinkability” and reduced weight. Like all Soviet combat submarines, she had a double-hull configuration. Armament consisted of ten launch tubes for the Amethyst submerged-launch, antiship missile, plus four 21-inch torpedo tubes (with 12 torpedoes).8 Her main sonar—called Rubin—was a large, cylindrical array system fitted in the bow.
On her sea trials in 1971 the K-162 achieved 44.7 knots for the measured mile—a still unbeaten world record. Her propulsion plant included two PWRs generating a total of some 80,000 horsepower. Her trials were impressive, albeit not without problems:
[U]nder 80% output of its power plant, according to the log, the submarine demonstrated a full forward speed of 42 knots, instead of the 38 knots according to specification. ... at speeds of more than 35 knots, “external hydrodynamic noise began to increase” that created a turbulent current while flowing by the submarine’s hull. The noise reminded them of an “aircraft’s hum.” And at the state tests, during a 12-hour full-speed mode, at a nuclear submarine speed of 42 knots, the conning tower entry door, three hatches, and a buoy fairing broke [loose].9
Observers believed the noise level to be greater than 100 decibels. According to one of her designers, “due to a number of tactical shortcomings of the missile weaponry, and furthermore, due to the significant underwater noise . . . inadequate service life of the boat’s primary mechanisms and equipment and the long time delay of its construction ... it was decided not to implement series production of Design 661 nuclear submarines.”10
The Papa SSGN was in service until about 1991. The exact status of the K-162 is difficult to determine. The submarine’s two VM-5-m reactors have a unique configuration, and the fuel cannot be removed by conventional defueling methods. The specialized equipment for this evolution “has been lost and must be remanufactured.”11 The K-162 is moored at Severodvinsk, near Shipyard No. 402 where she was built.
All of the Alfa SSNs also have been retired; the last, the K-123, employed in a training role, was taken out of service about 1995.
But how fast are the current Russian attack submarines of the Akula and Sierra classes? Based on Russian statements, the Akula appears to be faster than the Seawolf. How fast will the next-generation Severodvinsk SSN (Project 885) now under construction or her successor be?
The new attack submarine (NSSN), successor to the U.S. Seawolf will be slower. Based on the published report of the Navy’s independent characteristics review of the NSSN, a design speed of about 28 knots is probable.12 The report notes that speed is driven by evasion, mobility, and search requirements, but it states that “trading speed for lower cost emphasizes [the] necessity for retaining tactical advantage”—i.e.. quieting.13 Thus, cost has driven down the speed of the next-generation U.S. attack submarine, despite the high cost paid to provide a relatively small increase in speed in the Seawolf over the Los Angeles-class and the continued Russian emphasis on speed in their new SSNs.
The U.S. submarine community certainly is not in full agreement on speed requirements. Several submariners have expressed the view that the increase in speed in the Seawolf was not worth the cost, recalling that the Seawolf also is 2,000 tons “heavier” than the previous Los Angeles, which means a considerable increase in horsepower to reach 35 knots. Few are willing to place their comments on the public record, however, because the Nuclear Propulsion Directorate interprets such comments as criticism of the Seawolf. Richard Jortberg, the first commanding officer of the small, hunter-killer submarine Tullibee (SSN-597), has written: “In the operational area, people often questioned the slower speed of the Tullibee—16 knots. In my experience with the ship, I never found that to be a real problem.”14 Addressing submarine speeds in three categories (strategic, tactical, and escape), Jortberg concluded: “Tullibee’s slower speed would result in slower—but quieter—deployments. With good weapons, [speed] should not be a factor in tactics. It is questionable whether it would be a handicap in escape speed.”15 The issue of speed certainly is important in future U.S. submarine design. The questions of how fast is fast and how fast is fast enough appear to require more examination. [1]6
1 Adm. Bruce DeMars, USN, Press Conference, New London, CT, 5 July 1996.
2 See, for example, A. S. Pavlov, Warships of the USSR and Russia, 1945-1995 (Irkyusk, 1994), p. 35; and Bernard Prezelin and A. D. Baker III, Combat Fleets of the World, 1995 (Annapolis, MD: Naval Institute Press, 1995), p. 551.
3 The Russians credit the November with 28 knots at 80% power; it is believed that 30 knots were achieved on trials. The November had a two pressurized-water-reactor (PWR) plant that generated 35,000 horsepower; the Nautilus had a single PWR producing 15,000 horsepower.
4 Discussions with submarine designers Dean A. Horn and Harry Jackson.
5 The Albacore was in commission from 6 December 1953 to 9 December 1972. Although the Albacore has been out of service for almost 24 years, and the U.S. Navy has not built a diesel-electric combat submarine for 37 years, the Navy refuses to release the speeds achieved by the Albacore. Those speeds are widely known within the U.S. and foreign engineering communities.
6 Adm. H. G. Rickover, USN (Ret.), statement before the Seapower and Strategic and Critical Materials Subcommittee, Committee on Armed Services, House of Representatives, 29 October 1979.
7 The Alfa SSNs were built at the Sudomeldi/Admiralty yard in Leningrad (now St. Petersburg) and the Severodvinsk yard in the Arctic. A third yard, Krasnoye Sormovo at Goeldy (now Nizhniy Novgorod), also built titanium-hull submarines.
8 This evolved into the Soviet P-20 missile, given the U.S.-NATO designation SS-N-7 Starbright. This was the world's first underwater-launched cruise missile.
9 V. Bildin, "Ships of Postwar Designs: Design 661 Nuclear Attack Submarine," Morskoi sbornik (April 1993).
10 Bildin.
11 R. A. Shmakov, Malakhit design bureau presentation, "Problems of decommissioning of nuclear-powered submarines and environmental protection in Northern Areas," 15-16 March 1995.
12 VAdm. J. Guy Reynolds, USN (Ret.), New Attack Submarine (NSSN): Independent Characteristics Review (May 1994); study prepared for the Assistant Secretary of the Navy for Research. Development, and Acquisition.
13 See N. Polmar, "New Approach to Submarines," U.S. Naval Institute Proceedings, August 1996, pp. 87-88.
14 Capt. Dick Jortberg, USN (Ret.), "The Legacy of Tullibee," The Submarine Review, January 1989, p. 84.
15 Jortberg, p. 85.