The RPG-7 System Primer
The Soviet era design referred to generically now as the RPG-7 was the fruit of decades of design development in many countries: there were forces that had to come together in a perfect storm to father this excellent weapon system. The RPG-7 is most definitely not a “Rocket Propelled Grenade” as most people call it: it is more aptly described as a “Rocket Assisted Grenade that is Launched From a Recoilless Rifle” but the acronym gets cumbersome and wouldn’t fly in popular culture: it’s hard to imagine the hero in an epic movie shouting “RAGLFRR” instead of “R… P… G!” And, “RPG” really stands for Ручной Противотанковый Гранатомёт (in Cyrillic), “Ruchnoy” (Handheld) “Protivotankovyy” (AntiTank) “Granatomyot” (Grenade Launcher) in Latin letters. So, “RPG” it is.
The operation of recoilless rifles, adapted from the Bernoulli and Venturi principles and the landmark Davis Gun were necessary to hurl eight pounds of hell off of an infantryman’s shoulder towards an enemy. Rocket motors needed to be perfected to do so in a flatter, accurate trajectory, and the shaped charge with a carefully calibrated collapsing standoff and piezo-electric fuze had to be engineered to pierce our modern armors before the RPG-7 could achieve the effectiveness it has on today’s battlefields. What follows here is a SADJ special report adapted from Long Mountain Outfitters’ Foreign Weapons Training course. We hope it helps answer any questions that you might have on the system.
Shoulder fired rocket launchers are nothing new. Neither are rifles with integral grenade launchers. In the 18th century, there were seven foot long flintlock style rifles that a rocket shaft was aligned in, and a transfer bar operated the flintlock mechanism located out at the front of the launcher. The buttstock, trigger group, etc., look like a normal flintlock of the times, but the lock was out at the very front. There was another design from the same period where the buttstock was cylindrical and opened up at the shoulder end to make a cup style grenade launcher. The lock was able to fire either the musket barrel or the grenade launcher with the flick of a switch – this was in the 1700s. The grenade launcher was reversed and used mortar style of course. These are mentioned simply to show that weapons designers have been making man portable launchers and hurlers for centuries. It is only in the modern times that we have fine tuned the process.
The roots of the RPG-7 launcher can be found in the German Panzerfaust (literally “Tank-Fist” in German) of World War II. This was little more than a tube with a firing mechanism to launch a primitive warhead, but it gave the infantryman the ability to launch an explosive charge farther than he had been able to previously. Developments during and after World War II went in several directions, with some countries concentrating on the recoilless rifle principle and others looking more to shoulder fired rocket launchers.
In 1948-49, the Soviets introduced the RPG-2 system. The RPG-2 initially was a simple tube with a ballistically launched grenade that was fired from it. Behind the grenade was an ejection charge that basically threw the grenade forward from the tube, and an unassisted ballistic trajectory was followed by that projectile. In some later experimental rounds, a pyrotechnic fuze reportedly fired a rocket when it was safely in front of the operator. Those experimental RPG-2s had bodies that didn’t take the forces well, and the rockets were not reliably timed for firing so the accuracy degraded at distances beyond 100 meters. Stabilization came only from six thin sheet metal fins at the rear of the rocket motor, which did a reasonable job for accuracy. On the standard models, the six fins worked well enough. The RPG-2 series had an expected range of 150 meters, so the sights were fixed ladder types with no allowance for adjustment. Later models had some modifications, such as a rudimentary blast shield at the rear to help keep any blast-back away from the operator. There is recently discovered documentation to indicate that this disk was considered for keeping dirt from entering the rear tube, but the deflection explanation seems more plausible. This was neither a blast cone nor a venturi.
The RPG-2 system was manufactured until its replacement, the RPG-7, appeared in 1961. The interim designed RPG-4 that fathered the RPG-7 was not produced in large numbers. The Communist Chinese built and distributed the Type 56, an RPG-2 variant, and the Yugoslav’s built a much heavier similar launcher called the M57 that ingeniously added some sand as rearward mass.
It is strongly recommended against firing RPG-2, M57, or B-40 rounds as there has not been recent manufacture and the chemical compositions and fuzes are now untrustworthy. Unless the operator can verify recent manufacture, these should be avoided. The launchers themselves are simple mechanical devices so with fresh ammunition they would be fieldable – antique, outdated and outclassed – but fieldable. RPG-2 series grenades do not have timed safety self destruct fuzes, so a “dud” round will become a UXO (Un-Exploded Ordnance) hazard.