Rocket Propelled Grenade launchers.
Recognizing the need for a man-portable, short-range antitank weapon, several armies during WW2 developed a new kind of weapon – the antitank grenade launcher. These weapons fired specially designed projectiles (grenades) with HEAT (High Explosive Anti-Tank) warheads of significant diameter (caliber), as the effectiveness of the HEAT warhead is directly related to its diameter and the weight of the explosive charge. The first such weapons achieved service status in 1942-44 with American, British and German armies, as the M1 Bazooka, PIAT and Panzerfaust / Panzerschreck respectively. The Soviet army adopted its first antitank grenade launcher only in 1947, and circa 1961 it adopted probably the most famous, effective yet simple weapon in its class – the RPG-7.
Most antitank grenade launchers are separate shoulder-fired recoilless weapons, which typically consist of a smoothbore barrel, opened at both ends, a firing module with trigger, safety and ignition unit, and some sort of sights. The grenades are divided into three major types – RCLs, rockets, and dual mode (RCL+rocket). The RCL grenades are launched using a propellant charge, which is placed inside the barrel behind the grenade; as the barrel is open at both ends, some (actually most) of the propellant gases are ejected to the rear, effectively countering the recoil. The negative side of this system is the backblast, with the danger zone being as big as 20+ meters beyond the launcher. To minimize this problem, some variants (e.g. the German Panzerfaust 3) instead eject powder or fiber material at high velocity rearwards, thereby reverting to the original countermass form of the recoilless gun invented by Cleland Davies before WW1. The rocket grenades use a small rocket motor, attached to the grenade; sometimes this rocket burns out completely within the launcher tube, sometimes it continues to burn longer. In the latter case, the shooter must be protected from the rocket blast by some special means, such as a protective shield. The third, dual mode, system combines both principles, using the small RCL charge to launch the grenade from the tube; then, at the safe distance (usually about 10 to 30 meters) the rocket motor ignites, and further accelerates the grenade, greatly increasing the effective range. Obviously, the antitank grenade launchers are very simple and inexpensive; the most complex part of the system is the grenade (or, rather, the development of the effective grenade is quite complex and expensive – the production is quite simple), and, in most modern systems, the sights. The earliest or most simple launchers usually had open sights with some sort of scale for different ranges. Since the late 1960s, some grenade launchers (most notably the RPG-7) are fitted with more effective optical sights, with range-finding scales and complex aiming reticules. The most recent developments in electronics and lasers involve computerized sights with laser rangefinders and automatic aiming correction.
Early grenades used relatively simple warheads filled with standard explosives like TNT; modern warheads, designed to defeat the extra-thick composite armour of modern battle tanks, often further enhanced with ERA (explosive reactive armour), use dual warheads, filled with complex and highly effective explosives. In the dual warhead systems, a front warhead of smaller size is used to set off the ERA, and then a larger second warhead strikes the hull of the tank.
To further extend the usability of antitank launchers, the HEAT grenades are often complemented with warheads of other types, such as HE-FRAG (High Explosive-Fragmentation) for anti-personnel use, Incendiary, Thermobaric/FAE (Fuel-Air Explosive, used against soft targets, bunkers and personnel in the open or in defilade), smoke and some others.
It must be noted that only the most powerful antitank grenades can defeat the modern battle tank from the front. However, armor on the sides and on the rear of most tanks is much thinner, and thus much more vulnerable to the “poor man’s antitank artillery” – the antitank grenade launcher. The recent campaigns of the US army in Iraq and of the Russian army in Chechnya proved that antitank launchers (most notably, the old faithful RPG-7) still are quite effective against most modern armor, if used properly.