Fogg's Military "Fog" Bomb

The "fog" shrouded in enemy-occupied areas

"Fog" device is a practical and effective masterpiece invented by some non-governmental organizations with simple and common technology in the late19th century. At first, it was not a bomb detonating device, but a sound signal device placed on the rail to ensure the safe operation of the train in foggy days.

However, during World War II, the modified "fog" device was used flexibly. At that time, the British Special Operations Executive (the Secret Service directly led by Churchill during World War II) needed a large number of blasting equipment with simple structure and excellent performance in order to gain a firm foothold in the occupied countries and destroy the railway transportation system in Germany, so they improved the sound signal device placed on the railway track and formed the Mk.I "fog" bomb detonating device to be introduced in this paper today, which was used for train crushing. The use of the "fog" bomb detonating device has produced obvious effects and has become a layer of "fog" hanging over enemy-occupied areas.

Civil promotion for military use

The detonating device of MK.IA "Fog" bomb was improved to meet the needs of special agents, who wanted to create chaos in the occupied areas and disrupt the war dispatch and material transportation in Germany. Therefore, destroying Germany's railway transportation system has become the most obvious, feasible and easy-to-attack ideal means to achieve this goal. However, the destruction of the railway system is not just as simple as detonating the train. The best and most effective way is to derail the train with the war materials it carries, so that these war materials will be completely destroyed or delayed for a long time. In order to achieve this goal, it is necessary to have a detonating device, which can not only detonate the locomotive before it passes the bomb, but also prevent the train driver from stopping because of discovering the abnormal track in advance.

MK.IA "fog" device, the predecessor of bomb detonating device, was used in Danish railway department as early as 1893. This device can give the train driver a sound reminder when the stop signal (at that time, the light signal) becomes weak because of the fog. The Danish Railway Guide (1944) introduces the usage of this device in detail: three civil "fog" devices are arranged on the railway track in a specific order, which will cause a series of huge explosions similar to shooting when the locomotive passes by, reminding the driver to slow down. The application effect of the device is very obvious, and it has been widely used in the late19th century. MK.IA "fog" bomb detonating device completely borrowed this kind of civilian "fog" device, the difference is that one is used to ensure safety and the other is used to destroy.

The internal structure is the same.

In order to be portable, the "fog" device is made smaller. The existing civil "fog" device produced by Kynoch Company has a diameter of about 5.2cm and a thickness of 1cm. It consists of a chassis that can withstand a certain pressure and a thin metal bowl that is buckled inward and welded on it. The chassis is disc-shaped and welded with 3-7 anvils. Each anvil has a fire cap for ignition, and about 8 grams of black powder is placed around it, which is closely connected with the fire cap. A thin base is welded on the back of the chassis, and a clamp is fixed. This kind of clip is soft and elastic, which can tie the chassis tightly to the guide rail.

When the locomotive runs over the metal bowl, the pressure will trigger the fire cap, causing the black powder to burn and explode, making the metal bowl burst and making a loud noise to remind the train driver to slow down.

The MK.IA Fog Bomb Detonator improved by the British S.O.E is basically the same as the civilian Fog Bomb Detonator, but slightly different in size (diameter 4cm, thickness 1.5cm). Its working principle is also consistent with the civil type. However, its metal bowl and base are made of soft brass, and only the chassis is hard and thin metal plate. There are three fire caps in it, and a 5 cm long fast-burning fuse is wound around it and connected with black powder. The biggest difference between it and the civilian model is that a hole is opened in the side of the metal bowl, which is connected with the detonator or fuse with a 3.2cm long round tube. The gunpowder gas in the metal bowl detonates the detonator through it, resulting in a bigger and more violent explosion.

Simple and easy operation

In order to ensure the success of blasting operation, it is very important to place the initiating device of MK.IA "Fog" bomb in a reasonable position. According to the description of enemy blasting equipment published by the British War Affairs Office in 1945, the reasonable position of the metal bowl and chassis is not in the middle of the rail, but should be offset to the outside as far as possible. In this way, the circular tube on the side of the metal bowl can extend out of the rail as long as possible to avoid being crushed by the wheel edge before detonating the detonator.

The distance between the detonating device of MK.IA Fog bomb and the explosive is determined by the length of the fuse, one end of which is connected with the detonator and the other end is connected with one or more explosive groups. The burning speed of the fuse can reach about 7000m/s, that is to say, no matter how long it is and how many groups of explosives are connected, the MK.IA "fog" detonator and explosives explode almost simultaneously.

More advanced derivative model

MK.IA "fog" bomb detonating device caused great damage to the railway transportation in the occupied area, and Germany also took corresponding measures to avoid their attacks more effectively. They installed a wire brush in front of the locomotive to clean the rails. Because the detonating device of MK.IA "Fog" bomb is fixed with iron wire, it is easy to be cleaned, so the effect is greatly reduced. In view of this situation, American wartime intelligence agencies improved the design of R.R.TorpedoA3 "fog" bomb detonating device on the basis of MK.IA. The internal structure of this device is basically the same as that of MK.ia, but its appearance is quite different: its chassis is oval, which can be attached more tightly when fixed on the rail; Lead tape is used to tie instead of wire clips, and the lead tape can be close to the rail. These two improvements make the detonating device of R.R.TorpedoA3 "Fog" bomb more firmly fixed on the rail and difficult to be removed by wire brush.

The effect is amazing, laying the foundation for victory.

During the period from 1943 to 1945, there were 1525 incidents that damaged railways or trains in Denmark alone. In addition, the allied air strikes on the German railway transportation system caused great damage to the railways in Nazi-occupied areas, which greatly affected Germany's material transportation and war dispatch. According to statistics, in February of 1943, the freight volume of German railways was still1600 million tons/km, and dropped to 6.5 billion tons/km by the end of 1944, and dropped to1000 million tons/km after half a year, which was only 6.3% of the peak period. The traffic is basically paralyzed, and the coal supply is sharply reduced, which directly leads to difficulties in power generation and steel manufacturing, followed by a sharp drop in production capacity in industries such as gas, machinery manufacturing and food. Germany is unable to support the war, and defeat is a foregone conclusion.