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.
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 of the SALT I agreement. They could be launched from ground vehicles, aircraft, ships, and submarines, would be extremely accurate, and would be quite difficult to detect and intercept.
As a result of these studies, a joint project office to develop cruise missile components was started by the U.S. Navy and U.S. Air Force. While both services wound up choosing different models of missile (the Air Force selected a model built by Boeing), most of the components such as engines, warheads, and guidance systems were of a common design. The winner of the Navy competition was the B/UGM-109 model developed by General Dynamics. McDonnell Douglas is the second-source contractor for the missile, called Tomahawk.
The basic nuclear land attack version of Tomahawk, known as B/UGM-109A (also called TLAM-N), is launched into the air by a small rocket booster. Once airborne, a miniature jet engine about the size of a basketball ignites to power the missile at about 500 knots. It flies low to the surface (whether over the open ocean or land), held there by a guidance unit (MGU) being fed by a radar altimeter. The missile is kept on course by the MGU utilizing an inexpensive strapdown inertial guidance system. Once over dry land, the MGU is updated with position data from a system known as Terrain Contour Matching (Tercom), which matches the terrain under the missile with a three-dimensional database in the memory of the MGU. By using periodic Tercom updates, a TLAM-N is normally able to place its 200-kiloton W-80 nuclear warhead between the uprights of a football goal-post after a 1,300-mile flight.
While the nuclear-armed version of Tomahawk was being developed, it occurred to a number of people that perhaps the Tomahawk could be used to carry other things, and thus was born the whole family of conventionally armed Tomahawks in service now. The first of these was the B/UGM-109B Tomahawk Anti-Ship Missile (TASM), which replaced the TLAM-N MGU with a modified radar seeker and MGU from the A/R/UGM-84 Harpoon antiship missile. In addition, the W-80 nuclear warhead was replaced with a 1,000-lb/455-kg high-explosive warhead.