INTRODUCTION- 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.
WORKING- 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 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. This
engine weighs just 145 pounds (65 kg) and produces 600 pounds thrust burning
RJ4 fuel. The fuel load is 800 to 1,000 pounds (about 450 kg) of fuel at
launch, or approximately 150 gallons (600 liters). The missile has a cruising
speed of 550 mph (880 kph).
GUIDANCE
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
ground (out of the view of most radar)
Four different systems help guide a cruise missile to its target:
Ø IGS - Inertial Guidance System
Ø Tercom - Terrain Contour Matching
Ø GPS – Global Positioning System
Ø 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 motor. 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
systems 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.
The DSMAC system uses a camera and an image correlate to find
the target.
