Ordnance of the Week: D-4 122mm Smoke WP Projectile

The D-4 is a Soviet 122mm bursting smoke projectile. It utilizes a white phosphorus (WP) filler to generate smoke on battlefields. While these and other WP-filled munitions were designed to allow artillery units to mark targets or obscure troop movement, their use in warfare has been controversial due to the horrific burning properties of white phosphorus. White phosphorus is pyrophoric, meaning it ignites instantly upon contact with oxygen. EOD operators must take great care when approaching, handling, storing, and disposing of WP rounds to this pyrophoric nature.

Images of D-4 round from Bomb Techs Without Borders, taken in Kyiv, Ukraine, 2022.

There are several key identification features that will allow EOD technicians to identify a D-4 and similar bursting smoke projectiles. Soviet bursting smoke projectiles utilize markings that indicate the filler agent which generates smoke, the nomenclature of the round, and a black band. (1) But while these markings may certainly be helpful in identification, it is important to note that markings are not always standard, and that variations or discrepancies may exist. For example, previous field identification guides from the US Department of Defense indicated that the black band would be on the ogive of the projectile, rather than rear of the bourrelet, and that both the bourrelet and rotating band may be unpainted. As we see in this example of a D-4 round collected in Ukraine, this is not always the case.

The most notable key ID feature for bursting smoke rounds is the burster adapter. Burster adapters connect the fuze with the burster, which is an explosive cylinder running down into the center of the projectile. As seen in images and the measurements diagram, the burster adapter is recognizable for its clear break near the nose of the projectile and spanner holes for installation, and it extends outwards 29mm from the projectile body. (2)

Diagram from Iraq Ordnance Identification Guide, US Department of Defense, January 2004

Bursting smoke projectiles distribute their WP filler over a wide area to generate as much smoke as possible. To accomplish this, the burster runs down through the center of the projectile to detonate and push the filler from the inside out in all directions. As seen in the attached diagram from the USSR Sergeant’s Textbook for Rocket and Artillery Troops, the burster extends deep into the projectile body and is detonated by the fuze booster. (3) The burster ignites the WP filler and pushes it outwards, bursting the projectile body and spreading the now-burning WP filler over a broad area.

Diagram from Sergeant’s Textbook for Rocket and Artillery Troops, USSR Ministry of Defense, 1989

As noted above, the pyrophoric nature of white phosphorus demands certain safety precautions during approach, handling/transport, storage, and disposal of bursting smoke munitions like the D-4. It is common for WP munitions to leak around the junction between the burster adapter and projectile, which can cause spontaneous combustion if the round is exposed to air. Burning WP can create a crust which blocks oxygen from reaching lower layers of the substance. Breaking this crust can once again cause combustion. The only way to stop WP from burning is to completely eliminate its access to oxygen. Wet sand or mud can be used smother a WP round, as can completely submerging WP in water. (4)

Burning white phosphorus produces white smoke composed of particles of phosphorus pentoxide. While this gas is generally only a mild irritant in field conditions, in enclosed spaces such as indoor storage areas it may become significantly more harmful to one’s eyes, nose, and throat. (4)

As always, a special thanks goes out to Bulletpicker LLC. There you can find our Basic Ammunition Identification Guide for Ukraine as well as numerous technical and field manuals for conducting ordnance research!

Sources:

(1) Textbook for Ground Artillery Ammunition, USSR Ministry of Defense, 1970

(2) Iraq Ordnance Identification Guide, US Department of Defense, January 2004

(3) Sergeant’s Textbook for Artillery and Rocket Troops, USSR Ministry of Defense, 1989

(4) “Smokes, Fuels, and Incendiary Materials", J R Army Med Corps, 2002