Skip to comments.How Rocket-Propelled Grenades Work
Posted on 03/19/2004 7:42:12 PM PST by mhking
How Rocket-Propelled Grenades Work
|by Shane Speck
But why? Why are rocket-propelled grenades (RPGs) so prevalent? Where did they come from and just how do they work? It's obvious they're more than just a normal grenade simply because they're rocket propelled, but just what does that mean? In this article, we'll investigate the origins of rocket-propelled grenades, how they're used and what makes them so common in military conflicts all over the world.
Mortars, Rockets and Grenades: A Brief History
This need to attack from a distance, coupled with the invention of increasingly complex metalwork techniques, led to the invention of ever more complex devices for launching projectiles; in around 1500 AD mortars became popular as a siege weapon. A tube of metal from three to five feet in length, weighing several hundred pounds, would be placed on the ground and aimed into the air. Mortar shells would then be dropped into the tube and propelled upwards by an explosive charge. The mortar operator had relatively little control over where the shell landed, but despite this mortars increased in popularity and are still used today. A small mortar can easily be moved and operated by two people, and a small, high-quality shell can have the destructive force of a stick of dynamite: easily enough to destroy a small vehicle. The destructive power of the shells increases with size, of course - the larger the shell the greater the power - and mortars come in a range of sizes to reflect this. There is a trade-off between cost, weight and effectiveness. The mortar's usefulness as a weapon is limited by the lack of an accurate aiming mechanism and its relatively short range: Because the mortar shell has to go up before it can come down, much of its speed is dedicated to getting it far enough up into the air -- so against a ground target, it has limited reach.
You can solve the range problem by improving the path of the projectile - a straight line from launching device to target is far more efficient. Enter the rocket: 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. In fact, a large rocket can travel up to twenty miles. The equipment required for such rockets is not unlike that used in launching mortars. Essentially, all that is needed is a set of tubes mounted on a platform or towed by a small vehicle. While this is useful, in this form it is way too bulky to replace the easily deployed mortar.
Combine certain elements of these two weapons and you've got the basics behind a rocket-propelled grenade. A small rocket is mounted on a tube, which is then aimed and launched. It may not travel as far as a larger rocket - only a few hundred feet - but it is more portable, can be aimed directly at the target, and will still do the same damage as a stick of dynamite upon impact.
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. 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.
The projectile itself travels toward the target, usually exploding upon impact. However, some modern grenades use an electronic fuze system instead of a mechanical or chemical fuze so that the projectile will detonate after a particular time-span has elapsed.
Most RPGs follow this basic operational design, although different models feature various refinements and modifications. Some are designed to be most effective against troops; some are designed to work well against armored vehicles and tanks, launching high explosive anti-tank projectiles. The M-72 Light Anti-tank Weapon (M-72 LAW) is popular with American forces, and features a pre-packaged rocket which is fired and then discarded. The M136 AT-4 also features a disposable launch device, and its 820 feet (250 meter) range and re-usable night-sight bracket has led to it becoming the U.S. Army's principal light anti-tank weapon.
Although not favored by the U.S. Army, by far the most common rocket-propelled grenade in use today is the RPG-7, a Russian designed weapon closely related to the German Panzerfaust anti-tank weapon, dating from World War II. Like missiles, these grenades have a built-in rocket propulsion system. Let's take a closer look at the RPG-7.
Now that we know what an RPG-7 is, let's take a look at how one operates.
Firing an RPG-7
that has four stabilizing fins that are folded around it with two additional fins at its rear end. A cardboard container encases the back end of the stabilizing pipe. Inside the cardboard container, a squib of nitroglycerin powder is wrapped around the stabilizing pipe and a primer or charge of gunpowder is stuffed into the end of the stabilizing pipe.
The RPG operator or artillary person then takes this assembled artillery and loads it into the front end of the RPG launcher so that it lines up with the trigger mechanism.
After the RPG operator pulls the trigger, this is what happens:
There are several types of grenades that can be used in the RPG-7. Some have a point initiating, base-detonating (PIBD) piezoelectric fuze: meaning that they are impact grenades. And, many others have back-up time delay systems, so that if they have not reached a target in a certain amount of time (something like four and a half seconds) the grenade will self destruct. The most commonly launched grenades are a High Explosive(HE) or High Explosive Anti Tank (HEAT) rounds.
Impact grenades must be unarmed until they are actually fired because any accidental contact might set them off. Since they are usually shot from a launcher, they must have an automatic arming system. In some designs, like the one we describe above, the arming system is triggered by the propellant explosion that drives the grenade out of the launcher. In other designs, the grenade's acceleration or rotation during its flight arms the detonator.
As for the back-up timed delay, the same fuze mechanism that sets off the the rocket would set this off. The spark ignites a slow-burning material in the fuze. In about four seconds, the delay material burns all the way through. The end of the delay element is connected to the detonator. The burning material at the end of the delay ignites the material in the detonator, thereby exploding the warhead.
Tactics: How Are RPGs Used?
Buildings, vehicles with little or no armor and, of course, human beings are all vulnerable to RPG fire. In particular, the fragments from exploding grenades can cause considerable damage to troops, and this principle was used effectively against Mujahideen firing positions dug into mountain slopes. A rocket-propelled grenade would be fired above and behind the firing position, raining down shrapnel and rock onto the hidden troops.
Of course, rocket-propelled grenades are most efficient when deployed in small groups. Two or three shots at a vehicle from close range increases the chances of destroying the vehicle, and can even be effective in destroying an armored tank. A first shot takes out the driver's viewing prism, and further shots work their way through the armor, concentrating on one particular spot.
Helicopters, too, are easily ambushed when landing or hovering; rocket-propelled grenades downed both US Black hawk helicopters lost in Mogadishu and Somalia.
Given the effectiveness of well-used RPGs, what strategies are there for defense? When it comes to avoiding vehicle losses from rocket-propelled grenades, a tactic adopted by less well-equipped armies is to send in infantry screens. Armies with more resources may use bombs or napalm to sweep areas in which RPGs may be located.
Another obvious tactic adopted by the Russians when fighting against the Mujahideen between 1979 and 1989 was to remain at least 1,000 feet (300 meters) away from the enemy, out of RPG-7 and AK-47 Kalashinikov assault rifle range.
RPGs: The Future
Despite this, there is always room for modification. Lighter weapons with greater range and destructive capability are always being developed, and there may even be the possibility of automatic or semi-automatic rocket-propelled grenade systems.
The accuracy of rocket-propelled grenades is another area where improvements can be made. Laser guidance systems, though expensive, would greatly increase accuracy. An encoded laser could be trained on the target -- providing reference information to the rocket, thereby allowing it to make appropriate in-flight corrections to its trajectory. Other systems, perhaps utilizing GPS satellite technology could also become incorporated in future versions of RPG weaponry.
For more information on rocket-propelled grenades and related topics, check out the links on the next page.
If you want on the list, FReepmail me. This IS a high-volume PING list...
RPG . . . American style.
It goes boom. I like things that go boom.
I'm going to put this one on my Christmas list.
Whatever became of muttley? As he would say: "Poor Muttley want one."
I have a neighbor down the street whe is starting to piss me off . . .
Worth repeating. No discussion of shaped charge, no differentiation between a rocket, recoiless rifle and RPG. Lots of errors of omission.
Can you show me how to mke a nuclear bomb too? just kidding.
Some articles appear to indicate "Base Fusing", and some, which might be disinformation, indicate "center of the 'V' in the wine glass".
This is more than theoretical...B. J. Clinton's mentor, Caroll Quigley, clamed that "beam riding" [Shortwave to a target at night] was a Brit invention, yet we now know it was Nichtbein [sp?], a Kraut invention.
Similarly, claims have always been made that the very first V-2 rocket was fired at London, whereas the British expert on Rocketry has ALWAYS maintained that ANTWERP, Belgium, was the first target, out of HATRED for the Churches playing [via the Carillion] the ZIONIST National Anthem, HATIKVA!!! [The Hope!]
Would you please post the next pic in that sequence?
Most likely. It is possible that they are some odd RPG's UXO, but you are right they are likely mortar rounds.
You'll love this neat little round for the RPG-7, produced by the Bulgarian Vazov Machine-Building Works, located in the city of Sopot:
5 January 2001
Thermobaric warhead for RPG-7
Bulgaria has recently developed the GTB-7G grenade with a thermobaric warhead, introducing the potential to expand the basic RPG-7 Knut (Knout) portable rocket launcher into a true multipurpose weapon. The thermobaric warhead utilizes an advanced form of the fuel-air explosive concept.
The contents of the 93mm diameter warhead are scattered in an aerosol form on impact and then ignited to create a rapidly-formed, high-pressure blast wave, equivalent to that produced by the detonation of 2kg of TNT.
The blast effect is such that significant damage can be inflicted on structures, including field fortifications, and lightly armored vehicles.
When launched from an RPG-7 the GTB-7G grenade has a maximum direct-fire range of 200m, with an initial velocity of 66m/sec (the maximum possible range is 1,000m). The grenade weighs 4.7kg and is 1.12m long. It can be utilized with any RPG-7 launcher once the necessary sight adjustments have been made.
Other recently developed alternative warhead grenades for the fin-stabilized rocket have included variations of anti-personnel HE-FRAG.
The manufacturers are the Vazovski Mashinostroitelni Zavodi (Vazov Engineering Plant), based at Sopot.
The RGP-7 rocket launcher is in worldwide use and the GTB-7G grenade is now on offer for export.
The Bulgarian GTB-7G rocket grenade on the left reveals its long domed thermobaric warhead. On the right is an OG-7VE grenade with an anti-personnel HE-FRAG warhead, also from Bulgaria. (Source: Terry J Gander)
The ballistics of the two rounds are quite different.
I can understand if an AK47's effective aimed range is that low, but I thought the russian version of the .308 went a lot further than 300 meters...?
The limitation for the standard AK47/AKM rifle with 16-inch barrel is mainly the sights; Though the AKsight is graduated out to 1000 meters and that of the AKM to 800, there's no windage adjustment at the rear sight, and their sight notch is pretty coarse; 300 meters is a more realistic number...and the AK magazine even makes a supported prone position less effective.
The longer 24-inch barrel of the RPK squad automatic weapon version of the AK is fitted with adjustment for windage easily set by the operator, and the longer barrel offers both better ballistic performance from the M43 cartridge and the longer sight radius making longer range fire more effective....and the bipod fitted helps as well. Hits on man-sized targets at half a kilometer are quite possible with the RPK, and a short burst may result in a beaten zone with a better than 50% chance of a hit on a single individual out as far as half that again, well beyond what the usual AK can manage. And if a 1P29 4x telescopic sight is fitted, target acquisition becomes even faster and more effective, with adjustment for range being automatically compensated.
The PSO-1 4x telescopic sight generally found atop the SVD sniper's rifle is calibrated for a 1000-meter range for a humanoid target 1.7 meters tall, and the chevron-pattern reticle allows quick and easy choices of elevation at varying range without adjustment of the scope. That's a little farther than the best usual accuracy of a SVD, but the cartridge is certainly effective at that range, and some shooters are very, very good with their SVDs. I would not bet my life that a Dragonov-equipped sniper couldn't make that shot. And there are also more powerful and more modern telescopic and electrooptical sighting units that can be as easily attached to the SVD's side mounting rail as easily as the PSO-1 can be removed from it with the throw of a lever. But 600-800 meters with a SVD and PSO-4 is pretty easy meat.
The SVD *Oar* is not as handy a carbine as an AKM or AK74, weighing almost twice as much, but offering around three times the effective range. And while the old Soviet motor-rifle regiment's forces had only one SVD per platoon, the Russians in Chechnya have often included a SVD, sometimes two, per squad.
The 7,62x54mm rimmed cartridge of the SVD and PK machinegun is better compared to the US .30-06 cartridge. When we were sighting in SMGT or PKT coaxial machineguns fitted to T-55 and T-62 tanks, we commonly used a 55-gallon drum at 1000 meters as the sight-in target. Hitting one at 1500 meters was not at all a difficult task once sighted in, also about the effective range of the 100mm main gun. Getting on-target at a kilometer usually took a dozen or two dozen aimed single rounds, then the mounting and adjustment bolts were tightened down, and the gun fired full-auto to verify the burst was going where it was wanted. If it wasn't a windy day, it was easy.
Is that Val Kilmer ? Looks like him lol
I heard that sometimes an RPG-7 would misfire in such a way that the rocket did not fire, but the timer on the warhead would be initiated anyway, leaving the operator with the need to toss the assembly as far as possible and hit the dirt before it went off. Sure to ruin your day
I think Yehuda was thinking of the 7.62x54R fired by the Dragunov
Issued to each squad for long-range firepower (not really a sniper capability in the US sense of the word)
Is that Val Kilmer ? Looks like him lol
Perhaps he took his role as Col. John Henry Patterson in The Ghost and the Darkness about the maneating lions of Tsavo a bit too seriously....
It's true, and resulted in at least one US fatality in training, resulting in live firing training of RPG-7s to be cancelled. The delay between firing and self-detonation of the PG-7 grenade warhead is only 5 seconds, so the gunner has to be awfully fast. The rocket warhead travels at a speed of three footbal fields per second, per the US TRADOC manual.
The man's a walking encyclopedia.
Not if I can thumb a ride....
There's an excellent but brief description of both the RPG-7 launcher and the PG-7 shaped charge antitank round for it at the following website. But it should be noted that the PG-7 HEAT warhead is not the only one available for the launchers, or now commonly encountered for the RPG-7 and -14 series weapons.
Still, I somehow doubt that my pointing the article out to them would do them much good....
Stay Safe !
I have an optical night sight for the RPG7 for sale.. brand new in original issued plastic carry..
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