Saturday, 14 January 2017

Czechoslovakian Tank Building: First Steps

In the late 1930s, Czechoslovakia was the second largest exporter of tanks in the world. A small Eastern European country that only obtained independence in 1918 began to catch up with Great Britain, the world leader in arms exports. Of course, such impressive leaps in only 20 years of independence didn't start with nothing. The first steps were made with inspiration from the British and German tank building schools. This experience resulted in a series of experimental vehicles and the mass produced LT vz. 34 light tank.

Wheels and Tracks

Like Swedish tank building, Czechoslovakian tank building owes its existence and development during the interbellum period to Germany. More specifically, the Treaty of Versailles, which prohibited the Germans from developing or building tanks. As a result of this treaty, many engineers found themselves without a job.

The easiest way to find a new one was to search for a foreign customer, as there was no shortage of them in Europe. Czechoslovakia was one of them. Its army had only seven French Renault FT tanks which were rapidly becoming obsolete.

Overall function of Joseph Vollmer's convertible drive system, illustration from a patent.

Joseph Vollmer, one of the key figures in the Kaiser's tank building industry, continued his work here. Like many engineers of the time, Vollmer was deeply involved with the issue of improving mobility of tanks. The LK-II, Germany's first mass produced tank and one of his creations, was faster than the Renault FT, but even its 16 kph were not what was going to be needed in a new war. Sooner or later, military minds in every country would realize that a tank is not just an infantry support weapon. A tank's speed became a critical parameter.

One of the possible solutions to the speed problem was the convertible drive. It didn't only increase speed, but range as well, and reduced wear on the tracks which had rather short lifespans. Since Germany was forbidden from building tanks, Vollmer decided to cheat. He began developing a convertible drive chassis using the Hanomag Z WD-50 as a base. This vehicle was introduced in 1921 and quickly became popular. For example, the USSR produced it under the name "Kommunar".

Vollmer's design was not simple. A system was attached to the tractor that could transform it into a wheeled or tracked vehicle. The tractor would drive up on a wooden ramp, after which the crew could install wheels or remove them.

Hanomag Z WD-50 as a convertible drive vehicle.

In 1923, the Czechoslovakian Breitfeld-Daněk (Breitfeld, Daněk a spol) company bought a license to produce a number of Hanomag vehicles. The WD-50PS was among them. Vollmer offered his services to Czechoslovakia and piqued their interest. The engineer received 1.3 million kroner for a prototype and documentation.

A year later, the prototype was complete. It was called KH-50: "wheeled-tracked (Kolohousenka) with a 50 hp motor". The same Hanomag WD-50PS tractor was used as its chassis, but the engine was moved to the rear, and the driver was moved forward. The test chassis was sent to trials, and another prototype was built. Laurin a Klement and Tatra companies were introduced to the project around this time. Later, the second prototype was converted into a proper tank.

The KH-50 concept was similar to what the Germans would later build as the Leichttraktor, PzI, and several other tanks. The transformation from a tractor to a tank involved the installation of a turret platform and turret. The turret platform was bolted on, so it was possible to convert it back to a tractor.

 KH-50 during trials.

The KH-50 had a 37 mm Škoda d/27 gun. As an alternative, two vz.24 (Schwarzlose) machineguns could be installed.

After assembly, the first prototype was sent to the 305th Artillery Regiment, where it was tested as an artillery tractor. The vehicle was a lot more maneuverable than the Renault FT. However, as a fully fledged tank, it had some drawbacks. Its top speed on wheels was 35 kph, which was not much more than what regular tracked tanks were able to achieve in those days. On tracks, the top speed of the KH-50 was only 15 kph. This was caused by the fact that the engine was too weak for its mass. A logical conclusion was to increase the engine power.

 KH-50 as a tank.

In 1927, an improved variant of the tank called KH-60 was built. As with its predecessors, one prototype was made into a tractor and the other into a tank. The main difference from its predecessor was a larger engine, the Hanomag 60 PS. The chassis, turret platform, and turret were also redesigned.

The modernization brought improvements: the top speed grew to 18 kph on tracks and 45 kph on wheels. There are rumours that the tank was sold or given to the USSR for trials, but these rumours are not confirmed. However, it is known that one such vehicle with number 13362 was added to the Czechoslovakian army in 1930. As an interesting aside, Aleksey Surin, the future chief engineer of CKD, worked on the KH-60 as his first project.

 KH-60, a modernized variant with a larger engine. A special ramp can be seen in between the wheels that was used to raise or lower the wheels.

The last modernization of tanks from this series happened in 1929, resulting in the KH-70 tank. It had a 70 hp engine, which increased its maximum speed to a respectable 60 kph. However, its mass grew, and it wasn't possible to load the tracks (and especially wheels) indefinitely. For this reason, the Kolohousenka project was gradually shut down.

The convertible drive program later evolved according to the "medium class combined assault vehicle" (Kombinovaný střední útočný, KSU for short) program. Work on it continued until 1935, which led to the creation of Škoda S-III and Tatra T-III tanks. As for light tanks, subsequent work in Czechoslovakia followed a different direction.

From a Tankette to a Light Tank

By 1930, the Czechoslovakian army was still without its own tank. Foreigners helped once more, specifically Britain. Czech companies actively worked together with many European manufacturers in military and civilian matters. Foreign orders breathed a new life into Czechoslovakian tank building.

In 1930, the ČKD company, which included Českomoravská-Kolben и Breitfeld-Daněk, purchased a license to produce Carden-Loyd Mk.VI tankettes. Three tankettes were built in Prague that year. After military trials, it was decided that a thorough redesign was needed. ČKD began developing the P-I vehicle, and Škoda, which absorbed Laurin a Klement in 1929, launched the development of the MU series of tankettes. The military preferred the P-I, which was put into production as "tankette model 1933" (Tančík vz. 33).

 MU-6 tankette, 1932. Reminiscent of a real tank, it set the direction for further development of light tanks.

Meanwhile, Škoda continued working on improved versions of their tankettes. One of those improved vehicles was the MU-6, which began development in 1931. Despite its mass of only 3 tons, it looked like a real tank. Its hull was lengthened to 3.84 meters, and the vehicle received a classic layout with an engine in the rear and transmission in the front. The crew was increased to 4 men, two of which were placed in the turret. A 47 mm Skoda A2 gun was to be used as armament.

This was a proper tank, if not for one "but". The thickness of its armour was only 5.5 mm, so even an ordinary rifle could penetrate it from half a kilometer away. It wasn't surprising the the army rejected the design. The MU-6 was later converted into an SPG, which was also unsuccessful.

Despite that fate, the MU-6 was the first domestically developed light tank. Many solutions used in the design served as a foundation for the majority of Czechoslovakian pre-war tanks. The foundation was set, now what the designers needed was a worthy vision to follow. 

That vision was found in Britain. Naturally, it was the Vickers Mk.E. CKD already picked the Mk.E as a target of imitation in 1929, offering the army a draft of the light YNP tank, inspired by the British vehicle. The military did not pay attention to it, as they were focused on the KSU program.

 Experimental prototype of the P-II tank.

CKD tried again in 1932. Another project was presented to the Military-Technical and Aviation Institute (Vojensky Technicky Letecky Ustav, or VTLU), which was similar to the Vickers Mk.E in its characteristics. The mass was 7.5 tons, the crew consisted of 3 men. The tank was armed with two machineguns and a 47 mm Vickers gun.

VTLU examined the project and made their corrections. The A3 37 mm anti-tank gun, currently under development by Skoda, was used instead of a 47 mm gun. Instead of the bulky vz.24 machineguns, the lighter ZB vz.35 was used. The improved project was approved under the codename P-II (Praha II).

The first P-II with registration number 13.363 began trials in November of 1932. Even though it was a Czechoslovak design, its suspension could be traced back to the Carden-Loyd Mk.VI. This is especially obvious when looking at the reinforcement beam and its attachments. There is nothing bad about this: engineers readily took good ideas from each other.

The influence of the Vickers Mk.E could also be clearly seen in CKD's first light tank. This applied to the overall layout and the concept of an infantry support tank. The armour was also similar: 15 mm in the front and on the sides.

That's where the similarities ended. Even though both tanks had a leaf spring suspension with eight road wheels per side in bogeys, the design of the suspension was different. Aleksey Surin's suspension used a full leaf spring which was attached above the bogeys and acted as a spring for all of them at once. The P-II also had an unsprung road wheels in the rear. Like the Carden-Loyd Mk.VI, the P-II used sledge runners instead of return rollers. However, two rollers were added, one between the runners and one behind them.
The armament on the turret was installed in a very original fashion, but was changed before the tank entered production.

While the suspension of the P-II showed its British roots, its hull and turret had nothing to do with Vickers designs. Even though CKD used a front suspension, they didn't shorten the hull like their British colleagues. The tank ended up with a roomier driving compartment, which had enough room for a driver and a machinegunner, who also operated the radio.

The hull gunner had another task. He was also... the tank commander. Depending on the situation, the commander was either in the hull or in the turret, at the loader's station. This unusual crew layout was used on all Czechoslovakian light tanks.

The small dimensions of the light tank limited the size of the engine compartment. Because of this, the P-II received a 6 L 62 hp linear 4-cylinder engine. It couldn't accelerate the tank past 30 kph, but that was enough for an infantry support tank.

The turret and its armament deserves no less attention than the chassis. It was clearly built with the participation of Skoda engineers and, judging by its shape, could trace its ancestry back to the MU-6. Unlike the previous design, the new turret had a commander's cupola and a turret bustle.

Skoda SU, a late competitor of the P-II.

Trials of the P-II began in late 1932. It was obvious that the tank was a success. The tank was much better than the Renault FT or KH-60. Nevertheless, the military decided to play it safe, remembering the Kolohousenka. In total, the P-II traveled for 3400 km over the proving grounds in Milovice where the tank battalion was based. In February of 1933, negotiations between the army and CKD began over the mass production of the P-II, and a contract for 50 tanks of this type was signed on April 19th, 1933.

Skoda's design looked primitive compared to the P-I. Nevertheless, the Skoda SU became the foundation for Czechoslovakia's most produced pre-war tank.

Meanwhile, Skoda didn't give up on a light tank contract. In 1934, work began on the S-II or Skoda SU light tank. It had a 109 hp V-shaped engine. The chassis was completely different from that of the MU. The transmission was moved to the rear, and the suspension became more like that of the P-II, although the overall function was different.

Despite the more powerful engine, the mobility of the Skoda SU was similar to that of the P-II. The SU also had a more cramped turret with no bustle and a 47 mm Skoda A2 gun with two vz.24 machineguns, both of which were rejected by the army for use in tanks back in the early 1930s.

The S-II was simply unnecessary. However, Skoda did not panic and began reworking the tank to new specifications. Eventually they had their revenge over CKD, but that's a whole different story.

Czechoslovakia's First

The order for 50 tanks didn't mean that the P-II would enter production in its current form. The experimental tank was altered, mostly in the turret and armament. The military didn't like the idea of a gun mantlet that could move in two axes. This system was more vulnerable to enemy fire. Instead, the production turret had a separate mount for the main gun and the coaxial machinegun. The form of the turret also changed. The commander's cupola was improved: it became taller and observation devices were added to the sides, improving visibility.

Production of the P-II at the CKD factory in Liben.

The production of the P-II was organized in Liben, a suburb of Prague. POLDI Hutte from Kladno supplied the armour. This company is connected to delays in shipping the P-II. The quality of the first batch of armour was very low. The problems of quality never went away. The highly hardened armour was brittle and often cracked on impact.

Due to this delay, the first six tanks were only received by the 3rd company of the tank battalion on April 23rd, 1934. Military trials began, which would determine the structure of newly created tank units. As a result of the exercises, the P-II's place in Czechoslovakia's armour system was determined. It was placed in category II (cavalry tank with 15 mm of armour).

It's easiest to spot the differences of the mass produced P-II from its prototype from the top.

On July 13th, 1935, the Czechoslovakian army officially adopted the P-II under the index LT vz. 34 (light tank model 1934). On September 15th, the first tank regiment was formed in Milovice, and six LT vz. 34 tanks were sent there on December 18th with registration numbers 13.496-13.501.

Another 18 tanks with numbers 13.502-13.519 arrived at the 2nd company of the 2nd tank regiment stationed near Olomouc (Moravia) on January 8th, 1936. The next batch of 14 tanks with registration numbers 13.520-13.533 arrived at Milovice to form the 3rd company of the 3rd tank regiment. Later, this regiment was moved to Martin (Slovakia). The last batch of 6 tanks with registration numbers 13.534-13.539 was also sent there.

Vehicles of the 3rd company, 3rd Tank Regiment on parade in Prague.

Due to the growing military potential of Germany and its claims of Czechoslovakian soil, the latter had to quickly grow its army. The LT vz. 34 were reclassified as light reconnaissance tanks in 1937, and units armed with them became subordinate to infantry divisions. Since tank units began receiving superior vehicles, the LT vz. 34 were redistributed in 1938. Almost half (27 tanks) were sent to the 3rd Tank Regiment in Martin.

By the time Germany occupied the Czech Republic, the country's first tank was long obsolete. The LT vz. 34 did not interest the Germans that took trophies back to Germany. A few vehicles were sent to trophy exhibitions, one of these tanks ended up in Vienna. The rest remained in warehouses, although by 1940, there were plans to modernize them.

With all their drawbacks, the LT vz. 34 was superior to the PzII, not to mention the PzI. There was an idea to include them in the Germany army, but it was never realized. It was possible that the reason had to do with the small number of tanks in German hands, only 23. There was little reason to modernize a small number of tanks that could not even outfit a battalion. As a result, the LT vz. 34 remained in warehouses and were eventually scrapped.

 P-II at a trophy exhibition in Vienna.

The fate of the 3rd Tank Regiment was different. After the occupation of the Czech Republic, Slovakia became formally independent and these tanks ended up in its new army. The Slovakian military started out with 18 tanks of this type, later increasing to 21. The army had no illusions about the combat potential of the LT vz. 34. The tanks were kept in reserves and did not participate in combat. On January 1st, 1942, 16 tanks were reclassified as training tanks, and mothballed in mid-1943.

On August 25th, 1944, a group of Slovakian partisans occupied Martin and the Slovakian National Uprising began four days later. The worn out LT vz. 34 took part in it. Some tanks were dug in and fought as immobile bunkers, since their condition prohibited any other use. Slovakian rebels used these tanks until the end of October of 1944.

German tankers used the captured tanks as training aides.

In the fall of 1944, the Germans finally used the LT vz. 34. When German forces took the military base at Martin on September 22nd, 1944, they captured 10 tanks. The tanks were included in the Tatra tank division, where they served briefly. The poor technical condition of the tanks forces the Germans to send them to Pilsen for major repairs. Later, they tried to send the tanks to the Croatians, but this offer of assistance was rejected due to the tanks' poor condition.

The LT vz. 34 is overshadowed by later Czechoslovakian tanks. Nevertheless, this tank was not only the first mass produced tank developed in Czechoslovakia, but the foundation for later work. Developing the design, CKD engineers created the LT vz. 38, which is rightfully considered one of the best light tanks of WWII. This tank also influenced the design of the LT vz. 35, the main pre-war tank of Czechoslovakia. The LT vz. 34 was one of the best tanks in its class at the moment of its creation, inferior to its competitors in mobility alone.

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