Gravel mines
Encyclopedia
Gravel mines, also called Button mines were small U.S.
made air-dropped anti-personnel mine
s. They were used extensively during the Vietnam War
as part of the McNamara Line
. They were also used as a rapid-deployment area denial expedient, to provide a barrier during combat search and rescue (CSAR) operations between downed pilots or other endangered units and infantry threats.
The mines consisted of a small green or brown camouflage
fabric pouch filled with Lead(II) azide
and 30 grams of coarse ground glass between two sheets of plastic. No fuse
was required because the explosive became shock-sensitive after dispersal, i.e. able to be detonated without a fuse on contact. The explosive lumps came in wedge or cubed shapes and their plasticizers evaporated after three to eight minutes exposure to air.
To allow them to be handled and dropped from the air, the mines were stored soaked in Freon 113. Once released from their container, the Freon would evaporate in between 3 and 8 minutes, thereby arming the mines. The mines varied in size, from simple warning bomblets (Button mines), whose detonation was to be picked up by air dropped acoustic sensors and relayed to a central control centre, through to larger mines, while not powerful enough to kill a person outright, they were capable of wounding anyone stepping on it. The larger mines were fitted with a two tablet chemical system to gradually render the explosive inert, although the reliability of this mechanism is unknown.
The mines were also used by the U.S. during the Battle of Khe Sanh
, however a U.S. Air Force history described them as being 'little more than a nuisance', with the Viet Cong clearing the gravel mine fields using Oxen dragging logs and the mines became inert after a short time.
37 million gravel mines were produced between 1967 and 1968, though mines were produced into 1970.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
made air-dropped anti-personnel mine
Anti-personnel mine
Anti-personnel mines are a form of land mine designed for use against humans, as opposed to anti-tank mines, which are designed for use against vehicles...
s. They were used extensively during the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
as part of the McNamara Line
McNamara Line
The McNamara Line was an unofficial name for a series of defensive barrier projects initiated by the United States between 1966 and 1968 during the Vietnam War to prevent infiltration of South Vietnam by NVA forces located in North Vietnam and Laos.- History :Various schemes had been proposed in the...
. They were also used as a rapid-deployment area denial expedient, to provide a barrier during combat search and rescue (CSAR) operations between downed pilots or other endangered units and infantry threats.
The mines consisted of a small green or brown camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
fabric pouch filled with Lead(II) azide
Lead(II) azide
Lead azide is an inorganic compound. More so than other azides, is explosive. It is used in detonators to initiate secondary explosives. In a commercially usable form, it is a white to buff powder.-Preparation and handling:...
and 30 grams of coarse ground glass between two sheets of plastic. No fuse
Fuse (explosives)
In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...
was required because the explosive became shock-sensitive after dispersal, i.e. able to be detonated without a fuse on contact. The explosive lumps came in wedge or cubed shapes and their plasticizers evaporated after three to eight minutes exposure to air.
To allow them to be handled and dropped from the air, the mines were stored soaked in Freon 113. Once released from their container, the Freon would evaporate in between 3 and 8 minutes, thereby arming the mines. The mines varied in size, from simple warning bomblets (Button mines), whose detonation was to be picked up by air dropped acoustic sensors and relayed to a central control centre, through to larger mines, while not powerful enough to kill a person outright, they were capable of wounding anyone stepping on it. The larger mines were fitted with a two tablet chemical system to gradually render the explosive inert, although the reliability of this mechanism is unknown.
The mines were also used by the U.S. during the Battle of Khe Sanh
Battle of Khe Sanh
The Battle of Khe Sanh was conducted in northwestern Quang Tri Province, Republic of Vietnam , between 21 January and 9 July 1968 during the Vietnam War...
, however a U.S. Air Force history described them as being 'little more than a nuisance', with the Viet Cong clearing the gravel mine fields using Oxen dragging logs and the mines became inert after a short time.
37 million gravel mines were produced between 1967 and 1968, though mines were produced into 1970.
Specifications
The mines were typically deployed from SUU-41A/A and SUU-41B/A dispensers, with the dispensers packed into cluster bomb units with between 12 and 16 dispensers in each cluster bomb. A single bomb could contain between 1,470 and 7,500 mines. The bombs could be dropped from aircraft at between 60 and 6000 meters and at speeds of 370 km/h to 1300 km/h. The dispensers would burst at an altitude of between 200 to 300 meters, scattering the mines.| Name | Shape and size | Explosive content | Type | Notes |
|---|---|---|---|---|
| XM22 | Quadrant Circular sector A circular sector or circle sector, is the portion of a disk enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector. In the diagram, θ is the central angle in radians, r the radius of the circle, and L is the arc length of the... , radius 64 mm |
11.6 g of RDX RDX RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4... /Lead azide |
Explosive | |
| XM27 | Quadrant, radius 83 mm | 27.7 g of RDX/Lead azide | Explosive | |
| XM40E5 | Rectangle 45 by 32 mm by 10 mm | 0.54 g of Chlorate/Phosphorus based explosive | Illumination / Warning | "Wet" weight 6 g. |
| XM41 | Quadrant, radius 89 mm | 16.3 g of RDX/Lead azide | Explosive | |
| XM41E1 | Square, 70 to 77 mm | 9.4 g of RDX/Lead azide | Explosive | |
| XM44 | Square, 25 mm | T77 or XM114 electrical detonator | Warning | |
| XM45E1 | Rectangle, 45 by 32 mm | 0.7 g of RDX/Lead azide | Explosive | |
| XM65 | Rectangle 76 by 70 mm | 10.3 g of RDX/Lead azide | Explosive |
Dispenser configurations
- SUU-41A/A
- 150 × XM41E1 per dispenser (10 dispensers per CBU)
- 750 × XM40E5 per dispenser (10 dispensers per CBU)
- 650 × XM40E5 and 48x XM44 per dispenser (10 dispensers per CBU)
- SUU-41B/A
- 150 × XM65 per dispenser (10 dispensers per CBU)