Everyone knows about submarines - these are ships that float (go) under water. But in addition to submarines, there were also quite real underground boats, subterrins capable of moving underground, controlled by the crew inside.
True, they also had military functions, but nevertheless …
1. Most often subterins are referred to as secret developments of the "Weapons of Retribution" of the Third Reich
After the capture of Konigsberg, adits and tunnels were found in its suburbs, presumably left after the passage of such an underground boat. There was also an exploded structure resembling the subterrine itself.
There is evidence that the prototype (project "Midgardschlange" - "Midgard Serpent") could move on the surface, under water and underground. Internally, it had the same structure as a submarine, i.e. inside it is divided into similar compartments (central post, living quarters, compartment of the main power plant, etc.). On board were: an electric kitchen, a bedroom with 20 beds, three repair shops, several periscopes, a radio transmitter and 580 large cylinders of compressed air.
The crew of the subterrin consisted of 30 people. The dimensions are impressive - the length is over 500 meters, the weight is about 60,000 tons.
Promotional video:
The design parameters of the Midgard were fantastic: the maximum speed on the ground was 30 km / h, the rate of penetration in rocky ground was 2 km / h, and even 10 km / h in soft ground, 3 km under water.
Ahead was a large drill head, the same as those used in the mining industry for underground work, on which four drills with a diameter of 1.5 m were located. Nine electric motors with a total power of about 9000 hp were provided to drive the head. Additionally, there were three more sets of drills, which were replaced depending on the properties of the rock.
The undercarriage of the train, made on caterpillars, was serviced by 14 electric motors with a total capacity of 19,800 hp, the electric current for the engines was generated by four diesel electric generators with a capacity of 10,000 hp, for which there were 960 m3 fuel tanks.
Movement under water was carried out using twelve pairs of rudders and an additional twelve engines with a total capacity of 3000 hp.
As a weapon "Midgard" carried a thousand 250-kg mines, a thousand 10-kg mines and 12 coaxial MG.
Later, additional underground facilities were developed for Midgard:
Fafnir (in the Germanic sagas - dragon) - 6 m long underground torpedo.
Mjolnir ("Thor's hammer") - shells that were supposed to blast rocks, facilitating the movement of the subterrine.
Alberich was a reconnaissance torpedo that carried microphones and a periscope.
Laurin is a small vehicle for the crew to leave the subterrin from the ground.
Ritter (developer) in an explanatory note to the project proposed the construction of 20 "Midgards" worth 30 million Reichsmarks each, this was necessary for the implementation of the plan of attack on strategic objects in Belgium and France, as well as for mining British ports. According to the proposed plan, three hours after the start of hostilities, 15 enemy ports should be blown up.
2. Soviet subterrins
In the Soviet Union, the development of underground boats in 1937 was taken up by a group led by engineer Alexander Trebelev. They began by studying the excavation techniques of the mole. The animal wielded in a long wooden box, looking for hidden baits, unaware that a powerful X-ray machine was shining through it. People saw on a fluorescent screen an X-ray of all the techniques of a working little excavator. As a result of these studies, a small model of a mechanical mole was created. The electric motor set in motion the cutting devices and special "fins-paws", which served for the forward movement of the machine. During the tests, the model successfully passed the soil of medium density, leaving behind a round tunnel.
After that, at one Ural plant, they started building a real underground boat with a crew of one person. She could move in medium density soil at a speed of 10 meters per hour. It installed oxygen cylinders to maintain the driver's breathing, a gyrocompass, a protractor to determine the angle of inclination when driving, and much more. Gradually Trebelev came to the conclusion that it would be better * to replace the loosening mechanism with a special cutter, and to transfer the role of the hind legs of the mole to special jacks.
In 1964, the plant was built and produced the first Soviet nuclear-powered underground boat, named "Battle Mole". The underground boat had a titanium hull with a pointed bow and stern, 3.8 m in diameter and 35 m long. The crew consisted of 5 people. In addition, she was able to take on board 15 more troops and a ton of explosives. The main power plant - a nuclear reactor - allowed her to develop speeds underground up to 7 km / h. Its combat mission was to destroy the enemy's underground command posts and missile silos.
The first tests of the "Battle Mole" took place in the fall of 1964. The underground boat showed amazing results, passing the difficult ground "like a knife through butter" and destroying an underground bunker of a conventional enemy.
Further tests continued in the Urals, in the Rostov region, as there are harder soils, and in Nakhabino near Moscow …
The photo shows traces of tests. Subterrina passed here
However, during the next tests, an accident occurred, which entailed an explosion and an underground boat with a crew, including paratroopers and the commander, Colonel Semyon Budnikov, remained forever immured in the rock mass of the Ural Mountains.
In connection with this incident, the tests were stopped, and after Brezhnev came to power, the project was closed, and all materials were strictly classified.
3. Analogs of other countries
Machines similar in purpose to the German Midgard were also developed in England. They were designated as NLE (Naval Land Equipment - naval and land equipment) and were designed to dig passages through enemy positions, which could dig large trenches or tunnels through the no-man's land under cover of darkness and under the rumble of artillery cannonade. Through the dug trenches, tanks and infantry were supposed to penetrate into enemy territory and suddenly attack the enemy.
NLE developers had several names: Nellie ("Nelly"), No man's Land Excavator ("Excavator without human intervention), as well as Cultivator 6 (" Cultivator 6 ") or White Rabbit 6 (" White rabbit 6 "), which masked its military purpose.
In its final form, the "Nelly" was 23.47 m long, 1.98 m wide, 2.44 m high and consisted of two sections. The main section, which was located on a caterpillar track, resembled a very long tank and weighed 100 tons. The front section, which weighed about 30 tons, was capable of digging trenches 1.5 m deep and 2.28 m wide. The excavated soil was transported by conveyors upward and laid on both sides of the trench, creating dumps with a height of about 1 m. "Nelly" could move at a speed of over 8 km / h, removing thousands of cubic meters of soil in the process.
Upon reaching a predetermined point, the earth-moving machine must stop and turn into a platform for the exit of tracked vehicles moving behind it, for example, tanks, which must rise from the trench into an open space and start a sudden battle.
One motor would drive the cutter and conveyors at the front of the machine, while a second motor was used to propel the machine itself. But after the fall of France, the Nelly project was discontinued.
Only five of the smaller Nellys were completed by then. Four cars were disassembled at the end of the war, and the fifth was disassembled in the early 50s.