Rocket Propelled Grenade(RPG)
The idea of remaining safe while attacking from a distance has been and always will be a major driving force when it comes to inventing weapons. Basic devices such as the bow and arrow and even the boomerang were all developed to make it easier to kill the enemy while remaining as far away from danger as possible. This need to attack from a distance, coupled with the invention of increasingly complex metalwork techniques, led to the invention of mortars; a popular siege weapon. The mortar operator had relatively little control over where the shell landed. The range problem is solved by improving the path of the projectile - a straight line from launching device to target . A rocket makes a sensible choice, because it can easily be launched from a tube device and is capable of travelling for at least a mile. Combine certain elements of these two weapons and you've got the basics behind a rocket-propelled grenade.
At its core, a rocket-propelled grenade can be thought of as something like a rocket and mortar hybrid. It's an explosive projectile weapon with two separate parts; the grenade and a device for launching it. The launcher is basically a tube that rests on the operator's shoulder. It is open at both ends, and a projectile with a small rocket engine is affixed to the front end of the tube. Firing is usually accomplished through a trigger mechanism, at which point the grenade's rocket engine is activated and a short, high-powered burst of ignited gases launches the grenade for a short distance - maybe between 500 to 1,000 feet (150 to 300 meters) depending on the target and the skill of the operator. The projectile itself travels toward the target, usually exploding upon impact. An RPG operator should be aware of what's immediately behind him; the exhaust gases will flare out behind the device in a cloud of searing hot smoke.
Most RPGs follow this basic operational design, effective against troops; some are designed to work well against armored vehicles and tanks, launching high explosive anti-tank projectiles.