The history of these tanks, in general, is interconnected, albeit in a very intricate way. To begin with, each British tank unit in France had its own repair shop. Lieutenant Colonel Philip Johnson worked in one of these workshops. He took up the improvement of the Whippet tank and managed to increase its speed, and then developed the so-called "cable track", which differs from the traditional one in that the tracks in it were not connected to each other, but were fixed at intervals on the cable. The cable is rewound between the wheels, and the tracks … can swing from side to side. Such a caterpillar is lighter, wood panels can be inserted into the track plates. But then … if it breaks, then it will be impossible to repair it, because how do you connect the broken metal rope, that is, its ends?
Medium D during trials.
The very first tank D with a Philip Johnson track.
The maximum speed of the modified MK. V tank with this track increased to 20 miles per hour compared to 4.6 miles for the standard tank. The tank, as an experimental one, was assigned the index D, after which the experiments with the "snake caterpillar" (and they called it so!) Were continued. At the same time, Johnson developed a new and very promising suspension for the tank. And then the "genius of a tank war" F. S. Fuller decided that such a tank was exactly what was needed for his "plan of 1919", which provided, firstly, the continuation of the war in 1919, and secondly, the massive use of high-speed and amphibious tanks.
Churchill promoted the "middle D" as an important step in the development of the Royal Panzer Corps, but then the First World War ended and the cost of military equipment began to decline rapidly. Tanks D were planned to be made 500 in December 1918, then 75 in July 1919, and everything ended with 20 vehicles. However, a wooden mock-up of the D medium tank was shown at Woolwich in early 1919.
Wooden model of the D.
The tank was in many ways like the Whippet, deployed backwards! Engine with a capacity of 240 hp with. was located in the back, and the wheelhouse with four machine guns - in the front. This was in response to criticism of the Whippet, which had a poor forward view. The tank could overcome an obstacle with a height of 1.22 m when moving forward and 1.83 m when moving in the opposite direction. The cross-country ability, of course, was worse than that of the diamond-shaped tanks, but the tank had to float! Moreover, to move through the water by rewinding the caterpillars, which played the role of a kind of rowing blades.
A tank with a "backside" higher than a "front"!
Here you have to step back a little to find out: this was not the first amphibious tank of the Royal Panzer Corps, because the very first was the Mk. IX tank. To provide him with buoyancy, empty tanks were used, fixed on the sides and in the bow of the hull. The side doors were sealed with rubber gaskets, bellows were used to create excess air pressure inside the hull. Movement through the water was carried out by rewinding the tracks, for which special blades were installed on them. In addition, a high superstructure was installed on the hull of the tank, in which part of the equipment was located, and exhaust pipes were brought out through its roof.
This is how the "middle D" floated.
The amphibious Mk. IX, dubbed "The Duck", entered trials on November 11, 1918. He was forced to swim in the water area of the Dolly Hill base, and although the tank was very poorly controlled on the water and had a low buoyancy, the tests were considered successful. This arrangement of the vehicle excluded the placement of troops inside the hull (and the Mk. IX was just a "landing tank", the prototype of modern armored personnel carriers and infantry fighting vehicles) and the installation of powerful weapons on it. In addition, the end of the war in November 1918 did not allow the continuation of work in this direction. The only amphibious Mk. IX was subsequently dismantled for metal, but the experience gained during its testing helped in the construction of more advanced amphibious tanks later.
Mk. IX afloat. Rice. A. Shepsa
As for the amphibious tanks D, 11 were ordered for testing, but all of them were made of low-carbon, that is, not armored steel. The variants D * and D ** ("with a star" and "with two stars") are known. Weighing 13.5 tons, the tank had a speed of 23 miles per hour on level ground and up to 28 miles per hour downhill. Then two tanks in 1922 were sent to India for testing in the tropics. The tanks had an asbestos layer on their armor to protect them from heat in the sun, but both of them broke during the journey from the train station to the military camp, where they were abandoned.
One medium D * was produced by Vickers at the end of 1919. The hull was expanded to increase displacement, and the track width was also increased. The original three-speed gearbox was replaced by a four-speed gearbox, so the top speed was even slightly higher, 24 mph, although the tank's weight increased to 14.5 tons. But the tank did not swim better!
Medium D ** was also done by Vickers in 1920. The width of the hull was increased again and a new 370 hp engine was supplied. "Rolls-Royce". A 15-ton tank with it reached a maximum speed of 31 km / h, but it is not known exactly with which engine this speed was reached.
Two DM tanks ("modified" or "modernized") were produced in 1921 at Woolwich. In the fighting compartment, an additional dome was installed on top for the tank commander, but which reduced the driver's visibility even further. The mass of the tank increased to 18 tons, and the maximum speed dropped to 20 km / h. At least one such tank sank in the Thames and had to be raised, as the famous cinematographic Pathé magazine told about in 1921 - "He sees everything, knows everything."
"Middle D" overcomes a vertical obstacle.
Johnson was also tasked with developing a family of armored vehicles for use in the colonies. Johnson made a tank based on the Whippet with two machine-gun turrets and old tracks, but with his own new cable suspension. One was built at Woolwich as a "tropical tank" in 1922. It was tested at Farnborough but never developed. Until now, only one tank from this entire "family" of the first amphibious tanks has survived - Mk. IX with hull number IC 15, which is on display at the Royal Tank Museum in Bovington. As a result, the Johnson Design Bureau was closed in 1923, and not a single Medium D type tank survived in England.
American version of "middle D" (United States - M 1922).
However, the story of "Tank D" did not end there! Overseas, the specification for a new medium tank was prepared in the same year 1919. The weight of the tank was supposed to be 18 tons, the power density was determined at 10 liters. with. per ton. The maximum speed was supposed to be 12 km / h, and the power reserve was 60 kilometers. The tank had to be armed with a light cannon and two machine guns, and the thickness of the armor on it had to withstand the hits of 0.50-inch (12.7-mm) bullets at close range. The wooden model was created in April 1920. With some minor changes, the US Army Munitions Department (overseeing this project) authorized the construction of two experimental tanks of this type. The first of these was quite conventional in design, with a spring suspension, and received the designation M1921. But here in the ammunition department, drawings and specifications for the "serpentine caterpillar" and the suspension of the "average D" tank from England were received. Therefore, the second prototype was built with exactly this track and suspension and received the designation M1922.
M1922 at the Aberdeen Proving Grounds today. Hollow tracks are clearly visible, where wooden plates were to be inserted.
At the time, the US Army had to economize on literally everything. Therefore, there could be no question of building many of these tanks. They decided to build them only to preserve the experience. The M1921 was eventually built at the Rock Island Arsenal and delivered to the Aberdeen Proving Grounds in February 1922. It was powered by a 220 hp Murray and Tregurta engine. with., but actually issuing only 195! The lack of power limited the M1921's speed to just 10 mph.
M1922 on the move.
The tank was armed with a 6-pounder (57 mm) cannon and a 7.62 mm machine gun in a round turret. Another machine gun could be mounted on its small turret at the top. Trials of the M1922 were completed in 1923, and he himself was sent to Aberdeen in March 1923. Tests have shown that the carrying cable wears out very quickly and has been replaced with a chain. Interestingly, the track links of this tank also had wooden inserts. The suspension worked well and, although the tank did not have a powerful engine, it reached a speed of 16 mph. The car was even accepted into service under the M1 index and … immediately left in Aberdeen as a museum piece. Another tank is located in Anniston, Alabama. On this, the story of similar, like twin brothers, "tanks D" ended on both sides of the ocean!
