the middle of the boat to the torpedo room.
The actual weapons-loading process is quite rapid once the gear is assembled. The weapon is swung over on a crane from the dock or tender and gently lowered into the loading rack. Once it is aligned, the loading rack is rotated up about 45 degrees, and the weapon is winched down on a chain-powered hoist. When the weapon has completed its nearly 50-foot journey, the transit rack is swung back to the horizontal, and the weapon is laid into the waiting skids on the torpedo room racks. At this point it is secured to the skids and moved over so that another weapon can be loaded. In all, the boat can be completely loaded, including setting up and striking the loading gear, within twelve hours, all with minimum support from a tender or dock crew. Afterwards, when the deck structures have been put back in place, you would never know this is the path the weapons take to the torpedo room.
Loading a torpedo, while straightforward, is anything but simple. The first step is to move a weapon from the storage rack onto one of the loading trays. This requires a bit of brute force (Mk 48s weigh about 3,400 lb/1,545 kg) as well as some precision; even in this day and age, human brawn is still useful. Once the weapon is loaded onto the tray, the inner door (called the breech door) to the chosen torpedo tube is opened and a quick inspection is conducted. If another weapon has just been fired, the crew may need to remove a wire dispenser and/or some guidance wire (if it is a Mark 48 torpedo), or to check for wear on the tube. This little process, known as diving the tube, is a job best handled by those with narrow shoulders and long arms.
Once this is done, the loading ram carefully moves the weapon into the tube. At this point one of the torpedoman mates (TMs) connects the data transmission link, called an 'A' cable, from the back of the weapon (all U.S. submarine-launched weapons are equipped with such connections), attaches the guidance wire (if it is a Mk 48), and seals the breech door. Once the hatch is closed, the technicians check to make sure all the connections and seals are properly set, then hang on the tube a small sign: WARSHOT LOADED. One of the nice features on the 688I/BSY-1 boats is that once a tube is loaded, it automatically can tell what kind of weapon is loaded. On several control panels and status boards around the boat, the change in the tube's status to Loaded and what it is loaded with are noted and marked.
Once a decision to launch a weapon has been made (this always requires a look at the mission orders and the standing rules of engagement), then the technicians at the BSY-1 firing control panels up in the control room power on the weapon to warm it up. Then the fire control technician assigned to control the weapon loads targeting and other data into the weapon's memory system. In the case of an Mk 48, this includes speed settings and seeker head mode. For a guided missile like a Tomahawk, it involves loading a complete mission flight profile. Once this is done, the weapon is ready to be fired.
The process of firing a weapon from a torpedo tube is probably one of the most well tested procedures on the entire boat; it dates back many decades. With the weapon warm and ready to fire, the order is given, 'Make the tube ready in all respects!' This is not done lightly, for this is the first of a number of actions that radiates a great deal of noise into the surrounding water. Once the tube is flooded, the outer door or cap is opened, and the tube is ready to launch the weapon. The commanding officer gives the command, 'Firing point procedures,' when the other necessary steps (such as sealing the breech door) have already been completed.
At this point the captain issues the firing command, 'Match bearings and
What happens next depends on which weapon has been fired. If it is a guided missile, then the outer door can be closed, and the tube is drained and made ready for reloading. If the weapon is a Mark 48, then the decision will probably be made to leave the outer door open. This is because the Mark 48 trails a guidance wire behind it, which allows the boat to guide the torpedo as it runs up to ten miles from the launching point. At any time, though, the wire can be cut. If the sub is traveling too fast, or makes too sharp a turn, then the water flow may break the wire. In any case, until the need for the guidance wire is gone, the tube must stay in use.
Vertical Launch System (VLS)
One of the weaknesses of all U.S. attack submarines since the Permit-class boats hit the water has been the shortage of space for torpedo tubes and weapons stowage. For over thirty years, U.S. attack boats have always had four 21-inch/533mm torpedo tubes to deliver their weapons, and about twenty-two stowage positions to hold them inside the boat. This was not much of a problem so long as all that the boats had to fire were heavy torpedoes and the occasional SUBROC. But beginning in the late 1970s with the introduction of the UGM-84 Harpoon antishipping missile, and the early 1980s with the UGM-109 Tomahawk missile series, this began to pose a real problem for submarine planners and skippers.
For example, say a U.S. sub skipper wants to shoot Harpoon missiles at a surface warship. Submariners traditionally prefer to keep at least one torpedo in a tube as a just-in-case weapon, much as a police officer keeps a hideout weapon in an ankle holster. This means the maximum salvo size that can be fired at the target ship is three Harpoons. This might be fine, but against a target like a Kirov-class battle cruiser with all its antimissile systems, those three missiles will be soaked up like water into a sponge; the weapons will be wasted, and the target will be alerted to the presence of the sub. What clearly is needed is a way to stow more weapons on the boat and fire more of them at one time.
The designers of the Los Angeles-class boats anticipated this, because both the designs for Harpoon and Tomahawk were known at that time. Space was left in the forward ballast tank for twelve Vertical Launch System (VLS) tubes, each capable of storing and launching a Tomahawk cruise missile. In addition, space for the associated control and hydraulic systems necessary to operate the VLS system was left in a compartment forward of the torpedo room. Thus it was possible for a Los Angeles-class boat to carry and launch twelve additional cruise missiles without affecting the weapons stowed and fired out of the boat's torpedo room. This meant an increase of 50 percent in weapons stowage and a 400 percent increase in ready firepower (when firing cruise missiles) over a
