Shoulder-launched missile weapon

A shoulder-launched missile weapon is a weapon that fires a projectile at a target, yet is small enough to be carried by a single person, and fired while held on one's shoulder. "Missile" is used here in the original broad sense: today the word has a strong connotation with the concept of a guided rocket. There are two kinds of shoulder launched weapons. The first is the recoilless gun, which is essentially an open tube. When fired the reaction gases (with a momentum equal to the projectile) expelled out of the back of the weapon compensate the force exerted on the projectile. The other type uses rocket propelled projectiles; these typically also use a small recoilless charge to get the projectile out of the barrel and to a distance where the operator will not be hurt by the rocket's backblast; when the rocket ignites at a safe distance, it further accelerates the projectile or at least keeps it from decelerating in its trajectory. The smallest shoulder-launched rocket weapons are rocket-propelled grenades (RPG). There are also larger "dumb" shoulder-launched missiles, used in a similar way to an RPG, but with far greater destructive power. A number of specialised "smart" missiles are available in shoulder-launched forms, including (anti-tank guided missile) and man-portable air-defense systems (MANPADs), surface-to-air missiles used as anti-aircraft, typically using infrared homing and used to target helicopters and other low-flying aircraft.