Saturday 26 March 2016

Medium Tank Mk.I: First of the Maneuver Tanks

The end of the First World War coincided with the decline of vehicles designed by William Tritton. Drastic budget cuts meant that further development of heavy tanks in Great Britain stopped. As for the first post-war medium tanks, they turned out to be too heavy, and could not repeat the success of the Mk.A Whippet. In late 1918, development of the Medium Tank Mk.D began, directed by Lieutenant Colonel Philip Johnson. The result was truly revolutionary and could reach a record of 20 mph (32 kph), but a large amount of mechanical problems brought about the end for that tank. After trials, the tank was not approved for mass production, but it did not disappear into nothingness. Later on, the Americans used it as a basis of their Medium Tank M1921. In England, the Vickers company had a go at making tanks and attained success with its first steps, creating the successful Medium Tank Mk.I.

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The steel casting Vickers company started its rise to the spot of one of the largest arms manufacturers in the world towards the end of the 19th century. In 1897, it bought out Maxim Nordenfelt Guns and Ammunition Company, propelling the steel casters from Sheffield into leading positions in the small arms and artillery markets. Slowly, Vickers acquired shipbuilding companies and naval artillery producers. Finally, in 1919, they bought Metropolitan Railway Carriage and Wagon Company which, along with making wagons, was making tanks since 1917.

Vickers' rise to greatness was connected with two figures. Sir George Thomas Beckham was Vickers' chief designer. He managed new types of weapons that were developed and produced by the company. He is linked to another figure, Sir Arthur Trevor Dowson, the controlling director of the Vickers company from 1906 to 1931. Nearly all new developments at Vickers that had to do with armament were patented by these individuals.

During the First World War, Vickers, or rather its child company Wolseley, built armoured cars. The company had almost no direct connection to tank building. This changed in the early 1920s. The heavy and medium tank crisis was a chance that was too good to miss for Vickers. A decision was made to not compete with the Medium Mk.D, but to stake a claim on the barren light tank market.

In 1921, Vickers received a contract to develop and produce three light infantry tanks. The first prototype was ready by December of 1921 and sent to Farnborough, where a research facility was established at the 2nd Battalion of the Royal Armoured Corps. In 1928, it was renamed to MWEE (Mechanical Warfare Experimental Establishment). The tank later received a registration number: MWEE 7.

Vickers Infantry Tank No.1, Britain's first light tank.

Vickers' design was progressive and conservative at the same time. The Vickers Infantry Tank No.1 had a rhomboid hull, and its suspension was also similar to that of the WWI "rhombus" tanks, but there were many more innovative elements in this design.

This sounds comical, but a whole six years after the Renault FT and FCM 1A, the British finally put a turret on their tank. Vickers engineers equipped their brainchild with a fully rotating turret which fit all the tank's armament, three Hotchkiss machineguns. The bearings that the turret rotated on were outside of the hull. This solution was used on subsequent Vickers tanks.

There were innovations outside of the hull, too. The designers of the tank created a very compact fighting machine with a mass of under 9 tons. Despite the rhomboid hull, the tank's layout was classical. Compared to the "rhombus" tanks, the driver of the Infantry Tank No.1 lived like a king, and the commander had a cupola on top of the turret. The entire crew was housed in the front of the tank, and the engine compartment was isolated. This was enormous progress compared to the "rhombus" tanks where the engine was placed in the middle of the hull.

The second prototype, Vickers Infantry Tank No.2, was ready in July of 1922. It received the registration number MWEE 15. It repeated the design of the previous vehicle, but a 3-pounder (47 mm) gun was installed in the turret.

Trials showed mixed results. The tank reached a speed of 24 kph on a highway, which was very good for the early 1920s. The tank also performed well off-road. However, both tanks were plagued by transmission problems, and the design of the track links proved far from perfect. As a result of trials, the tanks were rejected.

18-pdr Transporter. Its chassis was used as a basis for the new tank.

It was clear to Vickers that their infantry tank won't cut it in late winter of 1922. Because of this, they did not build a third prototype, instead building a transporter for the 84 mm (18-pounder) field gun. Work on this vehicle, named 18-pdr Transporter, began in March of 1922. This vehicle had nothing in common with the Vickers Infantry Tank No.1. Instead of a step forward, it was a leap in comparison to any other vehicle currently in development.

The above applies to the suspension more so than any other part of the vehicle. The best thing that was available at the time was a half-rigid leaf spring suspension. Vickers engineers developed a system with two-wheel bogeys that were attached to vertical coil springs. New track links were developed, named No.9 Link Track. An 80 hp Wolseley motor was used, with the engine in front and transmission in the rear. The 18-pdr gun would roll inside the hull and the crew would sit on its perimeter, facing each other.

The first trials showed how progressive the transporter was. Vickers Infantry Tank No.1 was forgotten, and Vickers received an order to build a tank on the 18-pdr Transporter chassis. Interestingly enough, another Vickers tractor would become a chassis for a tank, but in Germany, not in England. There, a Vickers tractor was the basis of the Kleinetraktor project, better known as Pz.Kpfw.I.

Light to Medium

According to specifications, the new Vickers tank was also in the light category. Its maximum speed was rated at 15 mph (24 kph), but the military's appetites grew after the transporter reached a speed of 20 mph (32 kph) during trials. The crew would consist of 5 people, same as the Vickers Infantry Tank No.1. Since the tank was a light one, its armour was only a quarter of an inch thick (6.35 mm). This armour was rather questionable, as even the Renault FT had 16 mm of steel protecting it from rifle caliber bullets.

An experimental convertible drive Medium Tank Mk.I: "Wheel-cum-track Light Tank Mk.I". The driver's hatch has a completely new design.

The prototype that Vickers produced in late 1922 is often called Vickers Medium Tank Mk.I. Indeed, the tank was "promoted" to the medium class when it was accepted into service in the mid-1920s. The tank weighed in at 11.25 tons, which was still in the light tank category. Also, the name of the company was often missing in official documents. The manual simply calls it "Tank, Medium, Mark I". This is not surprising, as the tanks weren't only built by Vickers. According to the contract, only 13 tanks were built there, and 14 more were built by ROF Woolwich.

The appearance of the Medium Tank Mk.I coincided with two more novelties. One, the Ministry of War introduced letter indices for tanks. Strangely enough, the "pioneer" for this system was the A1E1 Independent, and the Medium Tank Mk.I was indexed A2E1. The second novelty was introduction of registration numbers. The first character was a letter, followed by numbers. The letter T meant tank, tractor, or transporter. Oddly enough, the Woolwich tanks received indices T.1 through T.14, so the very first Vickers prototype, made from mild steel, was indexed T.15.

An old system existed in parallel with the new one. This system consisted of a registration number of two letters and four digits, painted on the front of the tank. For example, T.7 had the registration number ME9923.

Layout of the Medium Tank Mk.I, figure from the manual.

The design of the new tank was similar to the 18-pdr Transporter. In addition to the 10 road wheels and 4 return rollers per side, another road wheel was added to the front. The idler mounts were also altered and a reinforcement beam was added to the return roller mounts. After trials of the T.15 pilot tank, another road wheel was added to each side in the rear. The driver was placed to the right of the engine, a 90 hp V-shaped aircooled Armstrong Siddeley. This engine is mistakenly called Vickers-Armstrong, but the two companies didn't merge until 1927. The transmission, like in the transporter, was in the rear, along with the fuel tanks.

A Medium Tank Mk.I in Vickers' courtyard, 1923. As you can see, the crew has no problems getting into the tank.

The Medium Tank Mk.I turned out to be larger than the Medium Tank Mk.A, or Whippet. Its height was a little over 2.8 meters. With a size like that, calling it light was indeed problematic. This excess height was connected with the front engine compartment, but it also allowed the crew's working conditions to be quite comfortable. Entering or exiting the tank could be done through one of three hatches, although the rear one could very well be called a door due to its size. The hull was assembled in the traditional manner for the time: a frame was welded together, after which armoured plates were riveted to it.

Medium Tank Mk.I CS with a 3.7" (94 mm) howitzer. In a way, this was the precursor of the German Pz.Kpfw. IV

The tank's turret was an evolution of the Vickers Infantry Tank No.1. It also rotated around its ring on three large bearings, installed outside of the hull. Vickers engineers decided to discard the dome shape and make the turret similar to the Rolls-Royce armoured car. The turret had a 3-pdr Vickers gun and four Hotchkiss machineguns (three along the perimeter, one AA). Another strange fact was the presence of two Vickers machineguns in the sides. The use of two different kinds of machineguns in one tank is a mystery.

Another interesting fact is the absence of HE shells from the tank. The Medium Tank Mk.I became the first vehicle to implement the controversial "machineguns are enough" concept. This mistake will come back to bite the British military during WWII. However, tanks armed with 3.7" (94 mm) howitzers had HE shells. These tanks received a special index, A2E2 Medium Tank Mk.I CS (Combat Support). Their ammunition loadouts also included smoke shells.

Worthy of Imitation

The first production Medium Tank Mk.I units started rolling out of the factories in 1923. They were mostly distributed among testing centers, but also made their way into the military on a trial basis. An intensive trial period followed, meant to discover the defects in the design so that they could be removed in the next batch. A convertible drive was tested on the T.15 pilot vehicle in 1926, renamed Wheel-cum-track Light Tank Mk.I. The convertible drive system was controversial. On one hand, the tank could convert to wheeled mode in one minute, which gave it an advantage over Christie's system. On the other hand, the tank's speed did not increase, but it became more difficult to control. In 1928, after a series of experiments and a modernization to Wheel-cum-track Light Tank Mk.I*, the idea was discarded.

A Ministry of War commission inspects a Medium Tank Mk.I. Note the open driver's hatch.

At the moment of its creation, the Medium Tank Mk.I was the best vehicle in its class. Nevertheless, it had many drawbacks, although none of them fatal. For one, the No.9 Link Track consisted of several parts, which were riveted to each other. During movement, the rivets could fall out and the tracks were disabled. The Hotchkiss machinegun mounts also proved difficult. The AA machinegun mount was also poor. Some tanks received six rollers for the turret, as three was not enough.

Medium Tank Mk.IA. Note that the tank still uses the No.9 Link Track.

The driver's hatch design was dangerous. In travel mode, the hatch flipped back on its hinges, giving the driver an excellent view to the left and right. The problem was that the hatch was not fixed in place. There were no problems on even terrain, but the situation became problematic when the tank went off-road. On a good bump, the hatch would slam shut, and the poor driver could lose a few fingers or get a smack on the head.Since the British didn't have tank helmets and the beret helped very little, this could have very unfortunate consequences.

Testing the maximum tilt of the Medium Tank Mk.IA. This angle lets you see the turret roof and redesigned AA gun mount.

The information regarding design defects was assembled and used to produce the second series of tanks, the Medium Tank Mk.IA. The contract was once again split between ROF Woolwich and Vickers. Woolwich vehicles received numbers T.28-T.43, Vickers vehicles were T-44-T.58. Externally, it is easy to distinguish these vehicles from the first batch by the simplified Hotchkiss machinegun mounts. In addition, the turret received a rear slope, which now housed the AA machinegun mount. The driver's hatch was also changed, and now it consisted of two parts. The thickness of the front of the hull and turret armour was increased to 8 mm.

Medium Mk.IA*, serial number T.58.

The No.3 Link Track was developed to replace the ailing No.9 design. The new design with its H-shaped indentation was so good that it affixed itself in British tank design for a good 15 years. However, the new tracks didn't appear on the tanks right away. The first tanks received the old No.9 Link Track. The replacement happened later. Three vehicles from the first batch (T.7, T.14, T.17) received Ricardo C1 engines. This required a change in the design of the upper front plate.

Even the earliest Medium Tank Mk.I were actively used. This tank has a three-colour camouflage and late model headlight covers.

The modernization did not end there. Someone from the Ministry of War finally discovered that the tank had two kinds of machineguns and that the front facing one existed independently of the main gun. The result was the Medium Tank Mk.IA*. The Hotchkiss machineguns were removed, their openings covered up with armour plates. Instead, a coaxial Vickers machinegun was introduced. A commander's cupola replaced the turret hatch, earning the name "bishop's crown". Towards the end of its career, the Medium Tank Mk.I received large protective covers for its headlights.

Medium Tank Mk.I, serial number T.7, with a Ricardo C1 engine.

The last tanks of the Medium Mk.I family were vehicles with serial numbers T.59 and T.60. Unlike the rest of the family, these tanks were referred to as light. The Tank Light Mk.IA(L) was more similar to the Medium Tank Mk.II. The hull machineguns and cannon were removed. Instead, two Vickers machineguns were installed in the turret. In 1925, both tanks were sent to India, where they were tested for three years. After that, they returned to their homeland and were scrapped.

Medium Tank Mk.IA* on exercises at Farnborough, 1935. The closest tank was converted to a command tank, the AA machinegun was replaced with a radio antenna.

Even though the Medium Tank Mk.II entered production in 1925, the first interbellum mass produced British tank remained in service for a long time. Until 1939, these tanks were used during exercises, teaching hundreds of British tankers. Several vehicles were sent to the colonies. One of them, presumably T.14, can be seen at the South African Special Services Battalion Museum.

In the 1920s, the Medium Mk.I was a trendsetter. The designers of the German Leichttraktor and American Light Tank T1 and Medium Tank M2 copied many design elements. Interestingly enough, neither the Germans nor Americans managed to duplicate the success of this tank in due time. By the time foreign "clones" were ready, Vickers already moved on from this design.

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