Shell, 155 mm, Smoke, DM 105

mm 155/39 TM; RDM 155 mm M139 and M114/39 ; SANTA BARBARA 155 mm SB 155/39 and 155/52 APU SBT-1 Howitzers, M114 155/45 and M114/39 ; Bofors FH-77B ; M199 Cannon for M198 Towed Howitzer; XM777 Lightweight Towed Howitzer. Development The 155 mm Smoke DM 105 projectile is one of the three projectiles developed as a result of the tripartite agreement entered into by Germany, Italy and the UK to develop the 155 mm FH-70 towed howitzer and its associated ammunition. The 155 mm Smoke DM 105 projectile was developed by Rheinmetall W & M GmbH (now Rheinmetall DeTec) and is manufactured by Buck Werke GmbH & Co of Bad Reichenhall. Rheinmetall DeTec has an Infra-red Smoke projectile under development. This projectile is ballistically matched to the DM 642 (RB 63) Cargo projectile and produces dense smoke for 4 minutes. A version which produces combined infra-red and millimetre-wave screening characteristics will also be available. The British Army have issued an Endorsed Staff Target (ST(L)4082) for an improved 155 mm Multi-Spectral Screening Smoke Shell to provide obscuration in the visual and near/far infra-red wavebands. A feasibility study commenced during 1995. Royal Ordnance (now BAE Systems , RO Defence) are developing a 155 mm Multi-Spectral Smoke Shell (MSSS) as a replacement for the existing 155 mm Smoke DM 105. It will supply a smoke screen to operate in the near and far infra-red wavebands, will be compatible with the Joint Ballistics MoU, and will ballistically match M483A1/DM 642 projectiles. Description The 155 mm Smoke DM 105 projectile is a separate loading, base ejection carrier shell with a high-grade forged steel body. Normally fitted with a mechanical time fuze, the 155 mm Smoke DM 105 contains (from the nose) a booster, an ejection mechanism and four smoke units stacked inside the projectile body. The base is recessed and held in place by six slotted pins. Located just above the base is a single drive band pressed into a preprepared ribbed groove. The nose and body sections are internally fitted with a steel support tube and an inner sleeve, this presents a smooth surface for the ejection of the smoke units. As the nose-mounted time fuze functions the flash from the fuze initiates the ignition train which is transmitted to the booster, a pelleted 6.5 g charge of black powder. The booster initiates the ejection mechanism which commences with the ignition of 15 g of black powder in a silk gauze bag inside a cylindrical metal case. The resultant internal pressure forces a plunger plate downwards to create pressure on the shell base. The slotted pins shear so that the base falls away enabling the four smoke units to be ejected. The flash from the ejection mechanism's black powder charge also travels down a centrally located flash tube to each of the four smoke units, igniting one or more of the three ignition cartridges in each unit so that the smoke mixture has been ignited approximately 4.5 seconds after ejection; that is, by the time each unit reaches the ground. Each unit contains hexachloroethane/zinc (HC) white smoke mixture in a cylindrical metal case. Each unit burns for 3 to 3.5 minutes (dependent on conditions) to create the smoke cloud which can be up to 200 m long, 50 m wide, and 10 to 15 m high at a distance of 150 m from the burst (under normal atmospheric conditions). The charge system used with the tripartite family of 155 mm ammunition is known colloquially as the `three cartridge' system. As its name implies the system is made up of three cartridges, the first two with a base charge and a number of increments. Cartridge 3 (Charge 8) is a unitary charge. Cartridge 1, the Charge Propelling, 155 mm, Howitzer, Charge 2, L2A1 consists of the Charge 1 and Charge Propellant Increment 2 combined to form Charge 2. The two weigh 1.21 kg and use SC/202 propellant. They are stitched together and should not be separated. Charge 1 L1A1 consists of a salmon pink cloth bag, containing 783 g of propellant SC/Z008 with an Igniter L19A1 containing 67 g of NC/200 and 18 g of G20 gunpowder stitched to its base. The forward part of the bag is recessed to contain the Charge Propellant Increment 2, a white cloth bag containing 311 g of propellant SC/Z008. Cartridge 2, the Charge Propelling, 155 mm, Howitzer Charge 7, L8A1 is made up from Charge 3 L4A1 and Charge Propellant Increments 4 to 7. Total weight is 7.55 kg. The Charge Propelling 155 mm, Howitzer, Charge 3, L4A1 consists of a smoke grey cloth bag containing 1.39 kg of NO25 propellant divided into two equal bundles. The charge bag is stitched into a combustible sleeve which in turn is secured in a smoke grey main charge bag. The sleeve and main charge bag are large enough to receive the propellant increments 4 to 7 which, when assembled with Charge 3, form the Charge 7 L8A1. The Igniter L20A1 containing 80 g of propellant NC/200 and 18 g of G20 gunpowder is fitted on the base of the main charge bag, and the mouth is fitted with a Velcro loop and hook. The Charge Propellant Increment 4 consists of an orange cloth bag containing 529 g of NO25 propellant. The Charge Propellant Increment 5 consists of a grass green cloth bag containing 1.56 kg of N/S 134-040 propellant together with a flash inhibitor pack. This pack contains 125 g of potassium sulphate powder and is positioned in the centre of the propellant. Wrapped and secured around the front end of the propellant is 17 g of lead foil. The Charge Propellant Increment 6 consists of a dark violet cloth bag containing 2.42 kg of N/S 134-040 propellant divided into two equal bundles, each of which has lead foil strip wrapped and secured around its front end. The Charge Propellant Increment 7 consists of a beige cloth bag containing 1.49 kg of N/S 134-040 propellant divided into three equal bundles, each of which has lead foil wrapped and secured around its front end. Cartridge 3 is the Charge, Propelling, 155 mm, Howitzer, Charge 8, L10A1 . This consists of a brown combustible main case and a pink combustible end cap. The end cap contains an Igniter, Propelling, Charge L23A1 mounted on a perforated disc. The propellant charge bundle consists of 12.48 kg of N/S 54.14 propellant sticks tied in five places using polyester/cotton thread and incorporating lead foil positioned under the top layer of sticks. All charges are ignited by the Primer Percussion DM191A1 which contains a primary charge of 1.25 g of nitrocellulose S536. When fired from the 155 mm FH-70 Towed Howitzer using the three cartridge system the 155 mm Smoke DM 105 can reach the following ranges: Charge 2 - range 3,900 to 5,900 m Charge 3 - range 4,800 to 7,500 m Charge 4 - range 6,200 to 9,500 m Charge 5 - range 8,500 to 12,500 m Charge 6 - range 11,200 to 16,800 m Charge 7 - range 14,200 to 20,900 m Charge 8 - range 17,000 to 24,700 m. When fired from the 155 mm FH-70 Towed Howitzer the 155 mm Smoke DM 105 has a maximum muzzle velocity of 827 m/s. It is anticipated that future 155 mm propellant charge systems will involve Modular Charge Systems (MCS). The German Army has already adopted the Rheinmetall DeTec Modular Propelling Charge System (MPCS) DM 72, as have Norway. and Malaysia . The United Kingdom has adopted the South African SOMCHEM M90 Bi-Modular Charge System. Authorised fuzes MT L92A2, DM 153 Equivalent projectiles GERMANY GERMANY Manufacturer Buck Werke GmbH & Co Type: 155 mm Smoke DM 105 Description: Standard specifications ITALY Manufacturer Simmel Difesa SpA Type: 155 mm Smoke DM 105A1 Description: Standard specifications Manufacturer Simmel Difesa SpA Type: 155 mm Smoke P5 Description: Similar to 155 mm Smoke DM 105. Can be configured to produce coloured smoke (green, red, yellow, violet or black)