Cutaway model of a Russian RKG-3M shaped charge anti tank hand grenade. The Russian abbriviation RKG stands for Ruchnaya Kumulyativnaya Granata; hand grenade with hollow charge.
This handgrenade is meant as a last ditch defence against armoured vehicles, and can be thrown to a distance of approximately 15 to 20 meters. It is –preferably- thrown from behind a cover to avoid the thrower from being injured by debris from grenade or target that can be lethal up to 20 meters.
The RKG-3M was used extensively during the 1973 Yom Kippur War.
Description and functioning of the RKG-3M :
The warhead exists of a sheet metal can (1) in which a red copper cone (2) is placed. The cone is fixated by means of a roll crimp. On top of the cone a sheet metal cap (3) is placed which forms the stand off (optimum explosion distance shaped charge from the target). The explosive charge (4, yellow) is placed below the cone A cilinder shaped hole is drilled in the base of the explosive charge in which a thin aluminium cup is placed. This lower side of the cup houses the booster charge (5, red), on top of the booster charge the wave shaper (6) is placed. The wave shaper delays the explosion front a littele so the detonation front will hit the cone in a more preferable angle. This improves the penetration depth.The base of the warhead is closed by a sheet metal screwed on cap (7) which also houses the pipe piece in which the duplex detonator (8) is placed.
In top of the stick of the grenade the all-ways impact fuze (9) is placed. Below that the drogue chute assembly (10) is placed. The assembly exists of a piston with a pipe at the backside and the arming pin (26) at the frontside. The arming pin is placed in the all ways fuze (9) and renders it safe. The parachute is wrapped around the pipe at the backside of the piston A spring wants to push the assembly outward, stoppd by a end cap (11) to which two spoons are attached. One spoon (12) is fixated to the end cap, the other one is a loose spoon (13) that has a hook that locks behind a hole in the stick and so fixates the cap to the stick. Both front ends of the spoons are locke under a rim under the warhead skirt.
The grenade is made ready to throw by pulling the safety pin (14), keeping the stick with the spoons in a firm grip. The pressure spring (15) will move the warhead appr one centimeter upward upon removing the safety pin, releasing the spoons (12,13).
The grenade is thrown. The spring (16) that wants to throw the drogue chute outward starts pushing -by means of a loose pipe piece (17)- upon the end cap. This forces the connected loose spoon (13) to rotate over the hook in the hole, releasing both spoons and the end cap (11,12,13). The drogue chute is forced out and the four radial wire springs (at 90 degr each) force the parachute to open. The drogue chute pulls out the piston with the pipe and arming pin further backward, removing the arming (26) pin from the fuze, thus arming the fuze.
The “All-ways”’ fuze exists of a sheet steel housing (18) in which the upper part of the fuze (19, blue) is screwed. A small steel pipe (also blue) with a ringshaped –inner- diameter enlargement (20) is connected to the upper part (19). Inside this pipe the firing pin housing (21, green) is placed, housing the springloaded (22) firing pin(23). The firing pin is fixated by two locking balls (24) which fall into a groove in the firing pin body. In the lower part of the firing pin housing two arming balls (25) are placed in a radial drilled hole. With the arming pin (26) in place , the balls are forced outward, preventing the Firing cap housing (21) from moving forward into the upper part (19, blue) of the fuze. A lead ball (27) with a throuh hole is placed behind the firing pin housing (21, green). Both the lower side of the sheet steel fuze housing (18) and the firing pin housing are conical shaped.
When the arming pin (26) has been withdrawn after throwing the grenade, both arming balls (25) fall inward. Upon impact, the inertia momentum of the lead ball will push the firing pin housing forward untill the locking balls (24) of the firing pin fall into the ringshaped groove (20, blue). This releases the firing pin (23) from moving into the duplex detonator (8), exploding the detonator and the main charge. The telescoped Upper fuze part (19, blue) and the firing pin housing (21, green) are held apart in flight by a very light pressure spring (28h).
If the grenade hits the grond with the stick First either sideways -instead of on the nose-, the lead ball will also move sideways. This will push both conical sides of the fuze housing (18) and the firing pin housing (21, green) apart, what means the firing pin housing is pushed forward, releasing the firing pin.
Of cource one will understand that RKG-3 duds are to be considered extremely dangerous due to the very sensitive all ways fuze. It is therefore not to be touched or moved.
Data : RKG-3M :
Diameter : 72mm
Length : 362mm
Weight : 1,07 Kg
Explosive charge : 0,567 Kg RDX/TNT
Penetration : 165mm Steel perpendicular
Regards, DJH
