The development of such a promising means of warfare as a tank set before its designers many different tasks, which had to be solved in a hurry, literally on the move, and solved effectively, since people's lives depended on their quality solution.
The French tank FCM 2C amazed people of that time with one of its appearance: two turrets, a long-barreled 75-mm cannon, four machine guns, a 13-man crew. There are two stroboscopes: on the front tower and on the rear, for the machine gunner.
For example, a full car reservation. It was necessary, understandable, but how to survey the surrounding area? After all, no one needs a blind armored cart either! Make "observation windows"? But they would be free to fly bullets and shrapnel! So it was necessary to think over this issue, which became very important for the tanks of the First World War.
The solution adopted for execution was simple and cheap. These were narrow "slits" (slots) in the armor, the probability of a direct bullet hitting which was extremely small. The periscopes, already used at that time in the infantry, were also tested. But it turned out that the field of view through the periscope is rather limited. The slots are better, although through them bullets could not only fly in, but poison gases and flammable liquids could also enter the tank. It was also impossible to make the viewing slits very narrow (less than the diameter of the bullet). In this case, you would have to bring your eyes close to them, which would also be unsafe.
Soon, however, it turned out that the slots, firstly, gave a limited view and the tank commander did not see the entire area surrounding the vehicle. And secondly, the bullets, breaking against the armor next to the viewing slots, scattered splashes of molten lead in all directions. Moreover, even the smallest such "drop" puts the tanker out of action! Ideally, a device was required that would allow the tank commander to have a 360-degree view, and not be endangered by bullets and shell fragments. At first they tried to solve this problem by installing "commander's turrets" on the tanks - quadrangular cabinets with four viewing slots. Looking at each one in turn, the commander memorized the "picture" of the surrounding area and could react to changes in the situation. But … he might not have noticed something, and he could not, sitting in his "booth", constantly spin like a top!
And a solution, and a very elegant one, was found and first applied in France on the FCM (Société des Forges et Chantiers de la Méditerranée) tank immediately after the First World War. It was based on … the stroboscopic effect. Moreover, this effect itself was used back in the Victorian era in the Zeotrope entertainment installation, which used a slotted cylinder with a series of images on the inner side of the cylinder. As the cylinder rotates, the images merge into one moving picture, and the gaps between frames seem to disappear. This is caused by the phenomenon of vision stability - since the human eye sees the world "at a speed" of 0.1 sec. That is, our brain simply does not see breaks at a higher speed. As we do not see breaks in frames on the film, although they are there, of course.
The first stroboscopic tank dome was installed on the FCM 1A prototype, possibly as early as 1919. And the same canopy was also installed on the FCM Char de Bataille prototype. Two strobe domes were mounted on two towers of the absolutely monstrous FCM 2C tank. No other French tanks are known to have been fitted with stroboscopic domes.
The experienced FCM Char de Bataille also had a stroboscope.
Tanks of other countries were not equipped with such impressive novelties. The British thought that in the next 10-20 years there would be no war in Europe, which means what is the point of rushing? The Germans had no time for tanks, in Russia and the tank "Fighter for Freedom Comrade. Lenin "was a marvel and it would not have occurred to anyone to improve it in such an expensive way in those years, and in the United States there was a rather strange attitude towards tanks after the war, besides, the opinion of the British was shared there. And only the French went to all these innovations, because they had a solid groundwork for the future and did not want to give it up just like that. As a result, strobe lights appeared on the heavy FCM 2C, but the impressive fleet of light FT-17/18 never received them.
French stroboscope device.
The device of the strobe lights installed on the FCM 1A and Char de Batayle prototypes is unknown, but it is known how they were arranged on the FCM 2C tank. Domes on the FCM 2C consisted of two cylinders inserted one into the other, an inner frame with seven triplex glass blocks, and an electric motor to rotate the outer body of the dome. This outer cylinder was made of 30 mm chromium-nickel steel. That is, it was, in fact, first-class armor! The stroboscopic slits were 2 mm wide, wedge-shaped, that is, wider outside than inside. It is clear that no bullet of the standard 7, 5-mm caliber could penetrate into such a hole, even with a direct hit into it. The slits were arranged in 9 groups of 5 slits each, with the spacing between them being about 20% smaller than the spacing between the groups. The outer shell of the dome rotated at a speed of about 250-300 rpm, which gave a quite satisfactory stroboscopic effect. The inner and outer shells visually seemed to dissolve, and the head of the tank commander was … "in an open field", so that he could freely survey the entire space around him in any direction! The entire dome was folded back, which was done to ensure the possibility of direct observation outside of combat conditions. The base ring of the stroboscopic dome had additional viewing holes fitted with glass blocks. It was argued that the French stroboscopic domes were resistant to bullets and gave the tank commander a 360 ° view, although the brightness of vision was somewhat reduced.
American tank Mk VIII with a stroboscope in the command room.
Although the Americans essentially froze their tank program and did not release new vehicles, between 1920 and 1925 the US Army's Combat Operations Division conducted numerous experiments with stroboscopic domes mounted on tanks. The American stroboscopic dome had only one slotted cylinder, not two like the French. The dome was said to be very vulnerable to 0.30 caliber rifle bullets. The project was closed in 1926 with the conclusion that conventional periscopes were superior to stroboscopic domes. For testing the dome, a heavy Mark VIII tank was prepared, on which it was installed in the command cabin. Other examples are unknown and, by the way, it is quite surprising that the Americans limited themselves to such a simple stroboscope design and did not even try to increase the thickness of the cylinder armor. Well, they'd make it 20mm thick. In any case, such armor at the time was too tough for rifle bullets!
The same tank, side view.
The stroboscope was last seen by the German tank designer Edward Grothe, who was invited by the Soviet government to lead the design bureau to develop new advanced tanks for the Red Army in the late 1920s. The medium tank, created by a team of engineers under his leadership, was something of a "show of strength" and the most advanced tank technology at that time. Therefore, is it any wonder that Grotte also put a stroboscopic dome on it. It was assumed that the tank will have two towers, one above the other with independent rotation.
Tank Grotte: all in cannons and machine guns and a stroboscope on the top turret.
And at the very top, a stroboscope for the commander was installed. "I sit high, I look far away!" - that's what one could say about such an arrangement, which in this case and for this tank would be completely justified. In 1931, only one prototype of the T-22 tank was produced, as the Soviet authorities believed that this tank would be too expensive and difficult to produce with the limited capabilities of Russian factories. No information was found about the characteristics of his stroboscopic dome. Well, the strobe lights were no longer used on tanks. That is, they were used on the French FCM 2C, ingloriously killed under the bombs of German dive bombers at the very beginning of the war during their transportation by rail!
