Monday 20 October 2014

World of Tanks History Section: Oboy Epicycloid

The end of the spring of 1915 was tough for the Russian Empire and its armies. An Austrian and German offensive that started on May 2nd threatened the entire front and the territory of the Polish Kingdom.

On May 4th, 1915, a fascinating letter reached Nikolai II's office, addressed personally to the Tsar. Its author was one Ivan Fedorovich Semchishin, a citizen of the city of Lvov, which was a part of the Russian Empire as of September of 1914. Semchishin's lack of fluency in Russian [unfortunately, the curious turns of phrase are lost in translation] was compensated by flowery prose and creativity. The letter was titled "A project of a machine for crushing trenches and military fortresses", and was immediately sent to military specialists at the Technical Committee of the Chief Military-Technical Directorate (GVTU). This organization processed proposals and inventions, which came in significant volume.

Changing the Landscape

The military engineers were no strangers to radical ideas, but Semchishin's project overcame even their imaginations. The author wrote: "If we had a large armoured barrel or roller with a motor inside which can spin on its axis, we could drive it over our enemies. My project, composed of a mobile fortress, realizes this principle and can be used to destroy fortified regions. It is called "Oboy"".

The author wrote of an armoured ellipsoid (which he called "epicycloid") of colossal size: 605 meters tall and 960 meters wide. Oboy's armour could withstand the enemy's bullets and shells, as well as mines. Two hatches were planned at each end, covered with robust caps. The crew would climb into them with 300 meter long rope ladders. Inside, the vehicle was equipped with a command post, projectors, and a wireless telegraph station.

Until recently, the Oboy was considered to have no armament, but archive documents show the opposite. The vehicle had provisions for heavy artillery. The design also included a sewer system, a ventilation system, a gas line, as well as "electric wires, telephones, elevators, fans, etc". The many floors of the vehicle would have hallways with living quarters, workshops, and stores. Semchishin's proposal was more than a house, but a whole mobile city.

The Oboy had no wheels, as it was itself a wheel. The vehicle would be propelled into motion by a system of steam engines, pendulums, and dynamo machines. The system produced "stores of energy, kinetic and potential". A flywheel would rotation into a rocking motion, allowing the ellipsoid to roll. The author did not specify how powerful this engine would have to be, but his design called for a mind-boggling maximum speed of 321 kph.

The engineers' verdict was laconic and absolute: the project is infeasible.

What if?

The military was correct. But now, after a century of technical progress, let's try to figure out why.

First of all, the Oboy would be impossible to build. There is no assembly plant today large enough to accommodate its size. Semchishin's supertank would have been taller than skyscrapers. There are also few buildings wider than 900 meters, none of which are capable of motion.

The vehicle would have to have been built near the front lines. In any other case, it would have expended its engine lifetime moving towards it, changing the landscape in its path.

The assembly of a prototype would be impossible to conceal from the enemy. If a team of saboteurs would be unable to impede such a colossal project, then an artillery barrage or a bombing run would leave it defenseless.

Even if the technology was available, the vehicle would crush itself when it moved. A mere 100 mm of armour would crumple like tinfoil under the Oboy's colossal mass.

A year later, another inventor proposed an idea of new armour. Using a cloth weaved from 1.9 cm thick rope and "so tightly wound that it would become like stone". This cloth, 71 cm thick, would be backed by 10 cm of steel. Even this invention, decades ahead of Soviet or American composite armour, would not protect the giant from its fate.

Two and a bit decades later, in July of 1943, the idea was reborn in miniature. Engineer-mechanic A.S. Dashevskiy proposed an ellipsoid "moving fortress". Its armour was 200 mm thick, but it was only 2.5 meters in diameter and 5 meters long. Dashevskiy's vehicle was like a mini Oboy.

Many spherical vehicles were proposed in the first half of the 20th century. Today, they become more and more known to those interested in military history. The Oboy "fortress destruction vehicle" remains the largest armoured vehicle designed in history.

Article author: Yuri Bakhurin. Yuri Bakhurin is a military historian, an author of many publications in regional and central scientific press: "Questions of History" magazine, "Military-Historical Magazine", "Military-Historical Archive", "Motherland", "Anthology of War", the "Reitar" almanac, and many more. He is also the author of the "Panzerjager Tiger (P) Ferdinand: Use in Combat" book.

Sources and literature:
  • RGVIA 803-1-1828 p. 123-134
  • RGVIA 803-1-1816 p. 140 and reverse
  • Y. Pasholok, Stalniye Shary Stalina, Moscow, Tactical Press, 2014
Original article available here.

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