What is Missile ?

Cruise missiles are jet-propelled at subsonic speeds throughout their flights, while ballistic missiles are rocket-powered only in the initial (boost) phase of flight, after which they follow an arcing trajectory to the target. As gravity pulls the ballistic warhead back to Earth, speeds of several times the speed of sound are reached.

Their performance has continuously improved because of technological advances in aerodynamics, guidance, propulsion, and warheads.

Almost all missiles are steadied in flight by stabilizing fins. In addition, guided missiles contain control systems to adjust their flight paths.

Although missiles can be propelled by either liquid-fueled or solid-fueled rocket engines, solid fuel is preferred for military uses because it is less likely to explode and can be kept ready-loaded for quick launch.

The very first air‐to‐air missile was an aircraft rocket designed primarily for antiballoon or anti‐Zeppelin work. Invented by Lt. Y. P. G. Le Prieur of the French Naval Air Service, the rocket came into use in 1916 by both the French and British air forces.

The simplest control systems are aerodynamic, making use of movable vanes or flaps that alter the flow of air past the stabilizing fins.

Four or five projectiles, each with a Congreve rocket‐like stick for stability, were connected to interplane struts on either side of biplane fighters. Salvoed by electric ignition, the unguided rockets were most effective against larger targets such as observation balloons, but successes were also scored against other aircraft.

A more complicated system—used especially in ballistic missiles, which often travel beyond the Earth’s atmosphere—is thrust vectoring.

Such engines commonly propel tactical guided missiles—i.e., missiles intended for use within the immediate battle area—toward their targets at twice the speed of sound. Strategic missiles (weapons designed to strike targets far beyond the battle area) are either of the cruise or ballistic type.

In this system the stream of gases from the rocket engine is deflected by placing vanes within the exhaust nozzle or by swiveling the entire engine.

World War II brought about the widespread use of aerial rockets, primarily as an air‐to‐ground weapon against armor. Early in the war, the Germans used fighters to lob a rather primitive conversion of their 21cm mortar shells to break up bomber formations.

The guidance system is the most important and sophisticated part of the missile. In tactical missiles, electronic sensors locate the target by detecting energy emitted or reflected from it.

Cruise missiles are jet-propelled at subsonic speeds throughout their flights, while ballistic missiles are rocket-powered only in the initial (boost) phase of flight, after which they follow an arcing trajectory to the target. As gravity pulls the ballistic warhead back to Earth, speeds of several times the speed of sound are reached.

Later, twenty‐four to forty‐eight R4M rockets were carried under the wings of a Messerschmitt Me 262 jet fighter. Salvo‐fired, they dispersed to cover an area about the size of a football field; a single hit was deadly.

For example, heat-seeking missiles carry infrared sensors that allow them to “home” onto the hot exhaust of jet engines. Antiradiation missiles home onto radar emissions, while one type of optically homing missile may “lock” onto an image of the target that is captured by a television camera.

During World War II, the Germans developed radio‐controlled and wire‐guided versions of the Henschel Hs 298, and the supersonic wire‐guided X‐4, designed by Dr. Max Kramer in 1943.

Almost all missiles are steadied in flight by stabilizing fins. In addition, guided missiles contain control systems to adjust their flight paths. The simplest control systems are aerodynamic, making use of movable vanes or flaps that alter the flow of air past the stabilizing fins.

Upon receiving information through its sensor, the guidance system relays instructions for course correction to the control mechanism through some type of autopilot contained within the missile or through commands transmitted from the launch platform.

Both missiles were intended to have proximity fuses, with the X‐4 testing an acoustic version. Their most important legacy was probably in proving the feasibility of wire guidance, which has been so widely used on antiarmor rocket weapons.

Ballistic missiles contain some type of inertial guidance system, which compares the missile’s actual speed and position to the positions that it must assume in order to hit the target.

The Cold War requirement to shoot down incoming nuclear bomb–laden enemy bomber aircraft created a demand within the U.S. Air Force for air‐to‐air missiles for its interceptors. The Lockheed F‐94 Starfighter and North rop F‐89 Scorpion were initially armed with 2.75‐inch‐ diameter unguided aerial rockets.

The guidance system then generates correcting commands to the control system.

A more complicated system—used especially in ballistic missiles, which often travel beyond the Earth’s atmosphere—is thrust vectoring. In this system the stream of gases from the rocket engine is deflected by placing vanes within the exhaust nozzle or by swiveling the entire engine.

The latter was an unguided rocket with a speed of Mach 3, a range of 6 miles, and a 1.5‐kiloton warhead intended to break up formations of incoming bombers. Aircraft carrying the Genie were routinely parked at civil airports during the years of the Air Defense Command dispersal program, a practice that might have disturbed modern environmentalist sensibilities.

Inertial guidance has become so accurate that the United States’ MX Peacekeeper ballistic missile, with a range of more than 6,000 miles (more than 9,650 km), has a 50-percent chance of delivering its 10 nuclear warheads within 400 feet (120 m) of their targets.