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Moscow Polytech
7 November 2017

Engineering secrets of the Kremlin ruby stars

To commemorate the twentieth anniversary of the October revolution on November 7, 1937, the project of ruby stars was commissioned and set in operation. What allowed the structure, developed within shortest time-limit, to last as much as 80 years without significant changes? What innovative materials and technological solutions were applied? The historiographer of MICE-MSUIE, the Moscow Poly Professor Valeriy Liubartovich tells us how one the masterpieces of the Soviet engineering was created.

“I belong to the students of the Moscow Institute of Chemical Engineering (MICE)”, - says Professor. – “This university was established in 30-s, in those years outstanding designers, engineers and scientists used to be invited for teaching, so that their scientific and production experience could be passed over to the new generation of Soviet engineers. And we, students, knew that among Professors of the university there were people related to creation of the Kremlin starts design, and we were proud of them. Department of material science was headed by Professor Aleksandr Landa, at the Department “Machine parts” there was an Associate Professor Gdaliy Mazur teaching, and at Department “Machines and apparatus for silicate production” Professor Aleksey Sokolov read lectures.

20 manufacturing and research enterprises were involved in developing and installing the ruby stars. Scientists and engineers had just half a year to make a technical design and implement all the works. That period of time was so short because then there were other stars decorating the Kremlin towers – made of semi-precious stones, and they required replacement. Initial Kremlin starts, designed by the engineers of the Central Aerohydrodynamic Institute (CAHI), were installed in October 1935, but did not last for a long time. Thousands of precious stones, with which the sickle and the hammer were encrusted, looked impressive in the glow of spotlights, but the Urals gems quickly darkened due to aggressive impact of environment.

Thus, the decision was taken to replace the works of jewelry art as soon as possible with a structure, more practical but no less impressive. The engineers confronted a few tasks: to develop a recipe of a glowing glass of ruby color, and, as well, to design a durable skeleton, capable of withstanding the wind, as well as a lighting system and supporting mechanisms. Since each of the five stars weighed around a ton, it was necessary to strengthen the towers’ skeletons as well. A specialist of the CRIHMash Aleksandr Landa was appointed as Project Leader, Gdaliy Mazur was appointed Chief Designer, Aleksey Sokolov made the first glass at the plant “The Red May”.

Glass, colored with selenium, acquires intensive red tint – hence the name “ruby”. The color depends on concentration of colloidal dyes, composition of the glass, the size of suspended particles and temperature regime. But several layers of the deep red color, when under sunlight, give a black shade. That is why for the monolithic glass of the ruby stars a few layers of 4-6 mm are used. The crystal transparent layer gives a good light reflection, the ruby layer dissipates the glow of lamps, while the milky-white color shades the red color. Thus, just a single lamp, installed in the center of the structure, provides an even distribution of the color along the whole surface of the star.

Already rolled out glass was cut to size of the beams and fixed with mechanical attachments, then hermitized by means of a special luting to ensure that no short cut occurs in wet weather. This luting, as well as the welded structure of the skeleton, was invented by Chief Engineer of the Project Aleksandr Landa. The construction frame, made of stainless steel, was covered with silver, then, by means of electrolytic plating, coated with a layer of gold 50 micron thick. That thickness was not chosen at random – a thinner coating could be damaged by crows, which repeatedly attacked golden Kremlin domes.

A five-pointed structure made of the cones, gathered at the center, mounted at the 70-meter altitude, is exposed to the wind impact. To ensure that the star does not fall due to the gusts of wind, a special mechanism was developed, consisting of bearings and axles. Owing to it, the structure can easily turn, like a vane, while under a strong wind the star always takes a position at 15 degrees, thus minimizing the load. It is worth mentioning that computing, required to calculate the project, did not exist then. And there was no time for testings, for example, like airing the model, as it is done with jets. Therefore, genial engineering solutions of Chief Engineer of the Project Gdaliy Mazur were based mainly on engineering intuition. It was also his idea to replace the lamps with the help of a special lifting bar with a gripper. The lamps work without rest, giving the most powerful light in the daytime. To avoid glass bursting from heat, a ventilation system works inside the stars.

There were only two occasions in the history of stars when they went out. During the war they were switched off and covered with canvas bags for the sake of disguise. For the second time the stars were switched off during filming of an episode in the film “The Siberian Barber”, at the request of Director Nikita Mikhalkov. The state of the structures is controlled daily by eye, and once in five years minor repairs are carried out.









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