Bizarre Armor Projects of the ’40s. Worm Tanks

Thanks a lot to Vlad for translating this glorious historical article.
Author: Jurij Bachurin
Sources: Central archive of the Ministry of Defense of the Russian Federation (ZAMO RF)

An image of a tank without tracks and rolls looks absurd. Even weirder are the looks of a combat vehicle which is moved by something like gigantic screws attached below the vehicle’s floor. In fact, among many others, the idea of a worm (or snail) drive was one of the more sane and viable ones.
Grigorenko’s “Driven worm”
On the 9th May 1944, one year prior to the Victory Day, first technical lieutenant Boris Grigorenko submitted the results of painstalking work via mail. The address was a short one: “Moscow – Kremlin”. The author proposed a new concept of movement parts which could easily handle “the crossing of muddy and boggy terrain, marshes with thickets, rivers, seas, sand, snow etc.”. He asked for help constructing and testing a prototype to fight against the Germans.
The invention was called “Driven worm”. Grigorenko named his variant of movement system based on the ancient Archimedes’ screw. He proposed to put a combat vehicle on steel rods with continuous screw surface. “The Driven worm represents a replacement for tracks, wheels and such. The rotation of the worm drives the vehicle forward” – the inventor reasoned. And with that, everything was said, because, according to the inventor, a tank with worm drive should have ideal terrain passability. Grigorenko even accounted for amortization on hard terrain, adding rubber rollers to the construction.
He did realize he was an amateur: “I’m not a technician or draftsman and do not have the capabilities to lay out everything in detail on paper”. The author hoped that Moscow would assign the revision of the drafts to specialists under his supervision and clearly hoped to be transferred to the capital.

The details of the idea were laid out by Grigorenko in a few words and accompanied by undetailed drafts. He proposed several variants of the installation of his “Driven worm”. The first was a cross-country vehicle of a “boat-like” build. The engine-transmission compartment of the vehicle was to be installed in the front. In the same place should be the bow deck and the driver’s cabin – judjing from the draft, a glassed one. The platform, covered by a tent, should be able to handle cargo of up to 2 tons. The second idea was a proposal of a GAZ-AA truck, where the rear wheels should be replaced with screws. And finally the last one was a draft of a screw-driven tank, which was quite abstract and not even commented.
Beketov’s screw tank
Even further were the thoughts and ideas of technical engineer V. Beketov. In august of 1942 he sent his project of a “screw tank” to the GABTU (department of inventions of the Main Tank-Automotive Management).
The description of the tank was in the sense of the author’s depiction of a perfect tank. Great firepower, speed, maneuvrability, stability, but first and foremost – the lack of vulnerable spots. A common weakness of all tanks was the chassis, and Beketov decided that he found a method to secure it: “The main idea for a positive solution of this question would be one where the tanks chassis would at the same time be part of the armored compartment”. Basically, the tank the author was proposing a tank consisting of one huge chassis, which was to be changed from a tracked drive to a worm one.

Beketov’s tank looked like a hollow armored cylinder which contained engine-transmission compartment and the driver’s seat. Quickly rotating, the cylinder should provide a forward movement. But this was not enough from the authors point of view: “Such an proposal is only realistic if two armored cylinders are connected by a solid link and rotate in different directions”. As such, the depiction was of a tank consisting of steel pipes of different thickness and diameter.

Two of these, composing the vehicles body, were to have a length of 6.2m and a diameter of 1.2m. The minimal thickness of these was estimated by Beketov to be only 10mm. The cylinder’s ends were to be of conical form, linked by four thick-walled pipes, and two others were to serve as passages for the crew.
The body cylinders were split by the author using thin walls: “These walls serve as comparment separators: engine, combat and steering. Also, they’re stabilizers for the cylinders’ interior.”. Aiming to disperse the vital centers of the tank, Beketov placed the engine-transmission in the middle. Access to engine was available from two sides in the interior. The author proposed to install the engine on a special metal carcass to provide space underneath it for oil and fuel. The battle compartments were to be placed under the turrets, four of which were to be installed on the tank  – two on each pipe. It did not bother the inventor which turrets exactly should be placed on the tank, he just elaborated that the turrets should carry 45mm guns paired with machine guns.
“The installation of four turrets provides powerful firepower  – in two directions, two turrets are able to provide fire, and in some angles, even three or all four would be able to fire.” – Beketov wrote.

But the main feature was still the screw drive. The author reasoned about its benefits – for example the automatical regulation of ground pressure. While traversing snow or swamps the pressure would be minimal, on hard ground – maximal.
Quite detailed were also the technical characteristics of the proposal: body of 7m length, 2.3m of height and 3m of width with a weight of about 28 tonnes. Regarding the quite thin armor of the vehicle, such weight wasn’t surprising. A pair of aircraft engines, each with a power of 250HP, could accelerate the tank up to 50 km/h. However, the answer of the GABTU to this project, as well as the “Driven worm”, remained unknown.
Both inventors thought on submitting their designs that they made a discovery. However the idea of a screw-based chassis preceded both of them. The first prototypes of such designs were created in the 19th century. In 1900 the inventor Franz Dergint filed a patent on a sliegh driven by the rotation of a screw.
After WWII, several cross-country vehicles driven by screw chassis were designed. Some of these are still in use today, being irreplacable for search-and-rescue operations in hardly reachable regions. And this means that some ideas were, in fact, implemented and are in service of the people.