Submarine: A Guided Tour Inside a Nuclear Warship

Torpedoes

The torpedo is the traditional weapon of the submarine, and the torpedoes that equip the U.S. SSNs today are truly awesome. For some years now, the U.S. standard torpedo has been the Mark (Mk) 48. This weapon, which first appeared in 1971, has gone through a series of different upgrades, culminating in the Modification (Mod) 4 version, which appeared in 1985. This version, designed as an intermediate upgrade to the next major version, allows for the greater speeds and deeper diving depths of the newer Soviet subs that were appearing at the time. As this book is written, about half the torpedoes being loaded aboard U.S. subs are Mk 48 Mod 4s.

^{Cutaway view of a Mark 48 advanced capability (ADCAP) torpedo. JACK RYAN ENTERPRISES, LTD.}

^{The business end of a Mark 48 ADCAP torpedo. The black cover is the acoustic 'window' of the torpedo's seeker head. JOHN D. GRESHAM}

A recent addition is known as the Mk 48 Advanced Capability (ADCAP) torpedo. Manufactured by Hughes, the ADCAP takes the basic Mk 48 package and adds the following new features:* A bigger fuel tank that provides for a 50 percent increase in range (about 50,000 yards), and a speed of 60+ knots.* A new data send/receive module, which packs 10 miles of guidance wire into the aft end of the torpedo and 10 more miles into the dispenser in the tube. This allows the submarine to clear the launch point and still guide the weapon.* A new combination seeker head/computer that uses electronically steered sonar beams to guide the weapon to the target. Earlier versions of the Mk 48 (like the Mod 4) used to have to 'snake' about their course to search effectively for a target. The head allows the torpedo to see almost all the 180-degree hemisphere ahead of the weapon. The computer controlling the whole system is designed to make the ADCAP the world's 'smartest' torpedo.

^{Tail section of an Mk 48 ADCAP torpedo. Inside the cover (labeled No Step) is the pumpjet propulsor, and a dispenser for ten miles of guidance wire. The silver unit behind it, which stays in the tube, contains another ten miles of wire. JOHN D. GRESHAM}

^{The back end of an R/UGM-84D Harpoon antiship missile. The locked cover, which protects the guidance fins, is removed prior to loading. JOHN D. GRESHAM}

With ADCAP, the submarine force arguably has the finest torpedo in the world. Not only is it fast, deep diving, and maneuverable, but it has a big warhead (650 lb/295 kg of PBXN-103 explosive) with an active electromagnetic fuse that allows the weapon to be detonated precisely where it will do the most damage. And it has more 'brains' than any other torpedo, with an amazing ability to outsmart countermeasures and jamming, as well as the capability to feed seeker-head data back to the BSY-1 system on Miami. This allows the fire control technicians to use the ADCAP as an offboard sensor. With such capabilities as these, it's no wonder that the crew of Miami calls the ADCAPs in her racks 'wish me dead' torpedoes.

Missiles

Strange as it may sound, the nuclear submarines of the U.S. Navy operated for over twenty years without a dedicated weapon for attacking surface ships. Part of the reason was the ASW focus of the SSN force during the 1960s and 1970s. Also, for much of that time their primary targets, the surface ships of the USSR, had no long- range weapons that could attack a sub while it was submerged. But with Soviet deployment of their first sea-based ASW helicopters and the ship-launched SS-N-14 Silex ASW missile, there was a clear need for a weapon that would allow a boat to stand off farther than the ten to fifteen miles a torpedo shot would allow. It had to be launched from a torpedo tube and carried as an all-up or 'wooden' round, requiring no maintenance and a minimum of support.

^{Cutaway view of an R/UGM-84D Harpoon antiship missile. JACK RYAN ENTERPRISES, LTD.}

^{Encapsulated UGM-84 surface-to-surface Harpoon antiship missile leaving the capsule as it clears the surface of the water. OFFICIAL U.S. NAVY PHOTO}

The weapon that was produced was the McDonnell Douglas A/R/UGM-84 Harpoon. This missile, which can be launched by ships, subs, and aircraft, was originally developed to allow patrol aircraft to shoot at Russian cruise missile subs on the surface. First deployed in 1977, it is approximately 17 feet/5.2 meters long, weighs about 1,650 lb/750 kg, and carries a 488-lb/222-kg high-explosive warhead. It utilizes a radar seeker that looks for surface targets and then initiates an attack 'endgame' on the target. Packaged inside a buoyant, torpedo-shaped launch capsule, it is fired from one of the normal torpedo tubes and rises to the surface. When it reaches the surface, the nose of the capsule is ejected, and the missile is launched into the air by a small rocket booster. Once airborne, the booster is dropped, an engine inlet cover is ejected, and the small turbojet engine is ignited. The missile then descends to about 100 feet above the surface, and transits to the area of the target ship at a speed of about 550 knots.

The Harpoon can be launched in a variety of modes. These include what is known as Bearing Only Launch (BOL), in which only the bearing to the target is known. There is also a series known as Range and Bearing Launch (RBL) modes, which require both range and bearing. Depending on the range to the target and the amount of neutral shipping in the area, the seeker can be set to RBL–L (Large) for open ocean situations, or RBL-S (Small) for tight, short-range situations. If necessary, several doglegs or waypoints can be programmed into the Harpoon's Midcourse Guidance Unit (MGU), which utilizes a small strapdown inertial guidance system to keep the missile on course. For submarines, there is even a self-defense option that allows the defending SSN to shoot the Harpoon 'over the shoulder' into a charging surface ship.

Once the missile gets to the target area, the seeker is switched on and begins to search an area shaped much like a piece of pie. If the seeker radar locates a suitable target, the onboard computer does a quick test to make sure it is a valid target (not a wave or a whale), and begins the endgame. The missile descends to an altitude between 5 and 20 feet (depending on the height of the waves) and heads for the target. At the discretion of the Miami's fire control technicians, the missile can be programmed to run straight into the side of the target ship (just a few feet above the waterline), or an optional 'pop-up' maneuver can be selected to make the missile plunge deep into the middle of the ship.

In any case, the exploding warhead will tear much of the guts out of any ship up to cruiser size. In addition, any of the jet fuel not used by the missile's turbojet will add to the destruction aboard the target vessel. It is a little-known fact that the warhead of the Exocet missile that sank HMS Sheffield in 1982 failed to detonate, but the residual rocket fuel in the missile's motor caused enough of a fire to eventually sink the ship.

The latest version of Harpoon aboard the Miami is the UGM-84D, which uses a denser fuel mixture to give it more range (reportedly around 150 NM/250 km). All in all, with some eighteen different countries using it, Harpoon is one of the most successful missile programs ever run by the U.S. Navy.

After the ADCAP, no weapon has done more to make the Miami deadly and effective than the UGM-109 Tomahawk cruise missile. Tomahawk is an outgrowth of a loophole that was discovered after the signing of the SALT I arms limitation treaty in 1972. While the exact origin of the cruise missile program is debated, it is generally assumed that Henry Kissinger, then the National Security Advisor, asked the Department of Defense (DoD) to look for classes of nuclear weapons that had not been considered during the SALT I negotiations. After some study, the DoD systems analysts came to the startling conclusion that air-breathing cruise missiles, basically cheap pilotless aircraft with nuclear warheads, would make an excellent weapon to circumvent the terms