A cruise missile is a guided missile, the major portion of whose flight path to its target (a land-based or sea-based target) is conducted at approximately constant velocity; that relies on the dynamic reaction of air for lift, and upon propulsion forces to balance drag. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy. Modern cruise missiles can travel at supersonic or high subsonic speeds, are self-navigating, and can fly on a non-ballistic, extremely low altitude trajectory. They are distinct from unmanned aerial vehicles (UAV) in that they are used only as weapons and not for reconnaissance. In a cruise missile, the warhead is integrated into the vehicle and the vehicle is always sacrificed in the mission. Cruise missile designs fundamentally derive from the German V-1 of World War II. Advances in transistor and computer technology have contributed to self-correcting avionic and aeronautical designs that allow missiles to be guided in flight, as opposed to only at launch. These advances developed into guided missiles and guided bombs, and later into the modern cruise missile. In 2011, it was estimated that a single Tomahawk cruise missile costs US$1,410,000. A cruise missile is basically a small, pilotless airplane. Cruise missiles have an 8.5-foot (2.61-meter) wingspan, are powered by turbofan engines and can fly 500 to 1,000 miles (805 to 1,610 km) depending on the configuration. A cruise missile's job in life is to deliver a 1,000-pound (450-kg) high-explosive bomb to a precise location -- the target. The missile is destroyed when the bomb explodes. Since cruise missiles cost between $500,000 and $1,000,000 each, it's a fairly expensive way to deliver a 1,000-pound package. Cruise missiles come in a number of variations (see the links at the end of the article for more information) and can be launched from submarines, destroyers or aircraft. When you hear about hundreds of cruise missiles being fired at targets, they are almost always Tomahawk cruise missiles launched from destroyers. Tomahawk cruise missiles frequently appear in the news because they are the U.S. weapon of choice for a variety of quick-strike operations. With all of the missiles in the U.S. arsenal, have you ever wondered why cruise missiles seem to come up so often? This documentary looks at cruise missiles so that you can understand what they are, how they operate and why they are ideal for certain scenarios. The Tomahawk is a long-range, all-weather, subsonic cruise missile. The missile was named after the Native American axe. Introduced by McDonnell Douglas in the 1970s, it was initially designed as a medium to long-range, low-altitude missile that could be launched from a surface platform. It has been improved several times, and due to corporate divestitures and acquisitions, is now made by Raytheon. Some Tomahawks were also manufactured by General Dynamics (now Boeing Defense, Space & Security). The hallmark of a cruise missile is its incredible accuracy. A common statement made about the cruise missile is, "It can fly 1,000 miles and hit a target the size of a single-car garage." Cruise missiles are also very effective at evading detection by the enemy because they fly very low to the ground (out of the view of most radar systems). Four different systems help guide a cruise missile to its target: IGS - Inertial Guidance System Tercom - Terrain Contour Matching GPS - Global Positioning System DSMAC - Digital Scene Matching Area Correlation The IGS is a standard acceleration-based system that can roughly keep track of where the missile is located based on the accelerations it detects in the missile's motion (click here for a good introduction). Tercom uses an on-board 3-D database of the terrain the missile will be flying over. The Tercom system "sees" the terrain it is flying over using its radar system and matches this to the 3-D map stored in memory. The Tercom system is responsible for a cruise missile's ability to "hug the ground" during flight. The GPS system uses the military's network of GPS satellites and an onboard GPS receiver to detect its position with very high accuracy. Once it is close to the target, the missile switches to a "terminal guidance system" to choose the point of impact. The point of impact could be pre-programmed by the GPS or Tercom system. The DSMAC system uses a camera and an image correlator to find the target, and is especially useful if the target is moving. A cruise missile can also be equipped with thermal imaging or illumination sensors (as used in smart bombs). Cruise missiles are 20 feet (6.25 meters) long and 21 inches (0.52 meters) in diameter. At launch, they include a 550-pound (250-kg) solid rocket booster and weigh 3,200 pounds (1450 kg). The booster falls away once it has burned its fuel. The wings, tail fins and air inlet unfold, and the turbofan engine takes over.

• published: 27 Apr 2015
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