Wednesday, 6 May 2015


German engineer Eduard Grote is most famous for two tanks: his insane 1000-ton colossus and a much more reasonable, but still too expensive, medium TG-1 tank. His other projects are less known, including at least one other superheavy, and one medium tank, which will be described here.

"December 3rd, 1931

Minutes of the VOAO Technical Commission with the participation of the People's Commissar of Naval and Military Affairs to review the new tank project by engineer Grote.

  • Chief of the experimental department at the Bolshevik factory, Barykov
  • VOAO Design Bureau #3 Chief, Ginsburg
  • VOAO Design Bureau #3 Senior Engineer, Professor V.I. Zaslavskiy, B.S. Andryhevich
  • Assistant to the chief of the 2nd RKKA HQ directorate, A.V. Konanchuk
The commission reviewed a preliminary project for a new tank by engineer Grote, indexed TG-3, with the following characteristics.

The TG-3 project is an attempt by the author to design a fast 30-ton medium tank with a convertible drive based on his first design.

Two parallel engines are placed in the front of the tank, each separately connected by crankshafts with gearboxes and final drives, powering the track on its side. The tank is suspended from five large road wheels on each side. The two rear wheels propel the tank when tracks are removed. All armament is placed between the middle and rear of the tank. The vehicle is controlled by pneumatics (compressed air from special compressors). Crew: commander, two mechanics, five gunners, total 8 men.

Having reviewed the project, the commission deems that:
  1. Combat elements
    1. Armament: the front placement of the engine means that the turret and armament are in the rear of the tank, increasing the dead zone in front of the tank to 8-9 meters. The double transmission set in the fighting compartment drastically reduces the free space in it, and severely limits the usefulness of its armament (some of it is simply inaccessible), and also results in a severely inadequate amount of ammunition on board. The tank armament can be used in the following ways:
      1. Short 75 mm gun: horizontal arc of 60 degrees.
      2. One 37 mm gun or machinegun in the main turret: 360 degrees.
      3. 37 mm guns in sponsons: 10-20 degree horizontal arc. If the 75 mm gun is being used, using these guns is difficult or impossible.
      4. Two machineguns in the rear sponsons: shooting from these is difficult to impossible. One of the machineguns can cover a 40 degree arc.
        In general, if one was to get rid of the unnecessarily bloated armament, the following could be used with greater effectiveness: 75 mm gun and ONE machinegun in the front, and ONE 37 mm gun and ONE machinegun in the turret. Only TWO guns and THREE machineguns, instead of the proposed FOUR guns and FOUR machineguns. 
    2. Visibility: the visibility for the driver is unacceptable, as the driver cannot see the ground in front of his tank closer than 25-30 meters. On an incline, the driver cannot see forward at all. The special periscope the author proposes to mount on the bottom of the front hull does not increase the angle of visibility. As a result, the tank will have unacceptable handling on obstacles.
    3. Ability to cross trenches and walls: equivalent to a 16 ton medium tank, not a medium-heavy.
    4. Fording depth: 0.75 meters. Less than the fording depth of a light tank. Water hazards are impassable.
    5. Medium speed: based on the experimental nature of the engines, their power will be no better than 600 hp, with a tank that is likely going to weigh no less than 35 tons (both of these are opinions of the commission). The proposed maximum speed of 50-60 kph and high speeds on tracks will be unattainable with this engine power. With the selected gear ratios, the tank will have a lower maximum and average speed (half as much).
    6. Transport via railroads: a 50 ton special platform for concentrated weight will be needed, and the tank will hang off the sides by 340 mm (total width: 3000 mm), which will make loading and unloading difficult.
    7. Range: the 400-430 Liters of fuel provide no more than 30 hours of work for a diesel engine or 23 hours for a gasoline engine at 70% of full power, which is half of the current norm, and is unacceptable.
    8. Armour: armour is no more than 20 mm.
  2. Design elements:
    1. Engine: the two-stroke experimental engine (oil or gasoline) is only shown to the commission via diagrams. The commission deems that there are no guarantees that the engine will have the necessary power or reliability, especially when turbocharged, as with Grote's previous engine.
    2. Engine compartment: the position of the engines and transmission make it impossible to use any of our aircraft engines, to cool them adequately, vent exhaust, or install additional components (compressor). These components are positioned very generally by the author, and are partially missing. Exhaust and hot air will find their way to the fighting compartment, where they will make the crew's work in a crowded space difficult. In order to function normally, the engines must work synchronously, but the synchronicity is violated when the tank turns, which will result in drawbacks well known in English Tailor tanks and our own experimental vehicles.
    3. Transmission: the provided dimensions of the gearboxes and convertible drive are impossible. The actual dimensions will be much larger, which will reduce the size of the fighting compartment, as stated above. The concentration of controls for the transmission, engines, and turns on an automobile type steering column will result in a complicated experimental design, which is unlikely to succeed, and is poorly thought through by the author. The transmission is primitive and inefficient. 
    4. Suspension: the suspension is too heavy and excessively large.
    5. The proposed road wheel balancer system is primitive, poorly thought out, and unreliable.
    6. The aforementioned drawbacks limit the implementation of turning wheels. The vehicle's problems with maneuverability will be multiplied by the overloaded rear drive wheels. This factor will result in high ground pressure, and will reduce performance on roads and bridges, especially in mud. It is not possible to turn using only the friction clutches when on wheels.
    7. The tracks are identical to the first proposal, but modified to make them easier to disconnect. The drawback of stretching has not been resolved. Installing spurs on these tracks will result in significant oscillations of the road wheels.
  3. Conclusions:
    1. As the first TG tank that has already seen trials, TG-3 is a project undertaken by Grote's initiative, who has a rich imagination and significant design experience, but no experience with tank designs. Both vehicles were designed by him alone with some corrections made to the first design after RKKA and OGPU critiques, but with no solid grounding in RKKA requirements. 
    2. The new TG-3 project does not satisfy RKKA requirements due to its overall design and aforementioned defects. In terms of the overall layout, it is even worse than the first TG. The commission deems further development of this project senseless. 
    3. Engineer Grote's desire for a special tank engine for tanks that weigh only 25-30 tons is notable. The commission considers that when designing tanks of this class, a special tank engine must be designed: small, simple, light, reliable, capable of being used in a variety of places.
    4. Based on points 1-3 and our exhaustion of all positive experiences resulting from Engineer Grote's work, the commission considers it pointless to seek further assistance from him in further tank designs."

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