Sunday 18 June 2017

Praga LTL and Pzw 39: Tanks for Neutrals

In May of 1935, an Iranian commission signed a contract with CKD for light Praga TNH tanks. At the moment, these tanks did not exist in metal, but the Iranians saw the potential in this design. A prototype was demonstrated in September of that year. The Iranian commission was so impressed that the order was increased to 50 tanks on September 10th. For this time, this was a very respectable amount of tanks for the export market. It's not surprising that representatives from other nations came to Czechoslovakia to find inexpensive and high quality light tanks. CKD's engineers managed to satisfy their new customers, creating new tanks for Lithuania and Switzerland, known as the Praga LTL and Pzw 39.

Lithuanian dead end

Vickers-Armstrongs Limited dominated the world market for armoured vehicles in the mid-1930s. In addition to the "6-ton" Vickers Mk.E, the British arms giant had another tank on offer. It is better known as the "Vickers 4-ton". This tank appeared as a further development of the Caden-Loyd Mk.VI tankette. First, a turret similar to the ones used on the Vickers Mk.E Type A was installed. Later, the hull was enlarged, and the result was named Patrol Tank.

In 1933, it was replaced by a thoroughly reworked tank with a Horstmann suspension, a new hull, and a Henry Meadows engine. This tank is known as the Vickers M1933. Its design was constantly improving.

Aleksey Surin's patent for an engine combined with a gearbox, designed for the Praga LTL.

A number of countries were interested in this tank, since the "Vickers 4-ton" was rather quick, inexpensive, and suitable as a reconnaissance tank, or, if necessary, an infantry support tank. Some countries bought samples for trials, others bought small batches. These tanks were overshadowed by the success of the Vickers Mk.E, but the number of countries that bought them was quite large.

Lithuania was included in the list of Vickers-Armstrongs Limited customers. In 1923, the Baltic state purchased 12 light Renault FT tanks, which were already obsolete by the early 1930s. In 1934, the Lithuanian government made a deal for 16 more light tanks. In May of 1936, these tanks were triumphantly presented in Kaunas, the capital at the time. 

The initial form of the Praga LTL, armed with a 37 mm Skoda A 4 Beta gun.

The contract did not mean that Lithuania would stop buying more tanks. On December 28th, 1935, a letter from the Lithuanian Ministry of Defense arrived at CKD's headquarters. Lithuania clearly noticed the success of the Czechoslovakian company, and decided to order its tanks here.

The requirements somewhat puzzled CKD's management. According to the letter, the Lithuanians needed a 5 ton tank with 6-13 mm of armour and a top speed of 50 kph. 4 tanks would be armed with Vickers machineguns, and 12 with 20 mm Oerlikon autocannons. The Lithuanians were eager for an answer: according to the letter, CKD should respond by mid-January of 1936.

However, CKD had nothing of the sort to offer. All it could propose was the Praga AH-IV-C, a variant of the AH-IV tankette with a cannon and a mass of 4.5 tons.

Experimental prototype of the Praga LTL at CKD, May 1938.

An almost year-long pause followed. During this year, it seems that the Lithuanian military realized that their requirements had little in common with reality. Armour that was thick enough to protect from rifle caliber rounds was no longer enough. It's not surprising that a proposal to develop a 9 ton tank followed in November of 1936. CKD was ready for this turn of events. The Praga TNH-L project was sent to Kaunas, an offshoot of the TNH design.

Detailed negotiations began in December. The Lithuanian delegation was shown the P-II (LT vz. 34) and P-II-a. POLDI Hutte was also hard at work, producing armour plates for testing. The Lithuanian delegation seemed satisfied, but suddenly rejected the TNH-L. The military suddenly remembered that many bridges in the country were rather flimsy, and the mass had to be limited to 5-6 tons.

A rear transmission required a radical redesign.

On February 12th, 1937, a draft project of a new tank was sent to Kaunas. One active participant of its discussion was Algirdas Sliesoraitis, an officer of the Lithuanian army and a functionary of the militarist fascist Iron Wolves association. Lithuania was seriously considering the Landsverk L-120 tank, but fortune smiled upon CKD,

The tank presented to Lithuania was called Praga LTL. It had two options for armament: either a 20 mm Oerlikon autocannon or a 37 mm Skoda A 4 Beta cannon, as well as two types of engines (air or liquid cooled). The thickness of the armour was increased to 25 mm. The design was clearly better than the L-120. t's not surprising that a contract for 21 LTL tanks at 570,000 kroner apiece was signed on May 26th, 1937.

The approved variant weighed 5.6 tons and was armed with a 20 mm autocannon. The requirement to drop the mass meant that the size of the hull had to be reduced; it was 40 cm shorter and 10 cm narrower. In addition, the transmission migrated to the rear, and the engine was installed at an angle to fit into its compartment. The 7 L Praga F-IV 125 hp engine was taken from the amphibious tank of the same name.

The tank received modernized observation devices and a new turret.

According to the contract, the first Praga LTL prototype was expected for trials no later than in 7 months, or by January of 1938. The delivery of the tank was late due to the fault of the armament manufacturer. Since CKD was not at fault, they managed to avoid being fined. The Lithuanians weren't in a hurry either, and a commission arrived in Prague only on May 4th, 1938.

The tank that entered trials was overloaded: its mass was 7.2 tons. On the other hand, the top speed was 55 kph. The tank also received an improved turret and observation devices. The first week of trials was accompanied by a number of breakdowns, the biggest of which was the breaking of the gearbox. The tank was finally perfected by August 29th, 1938. Trials continued, and the tank traveled for another 3500 kilometers by the end of 1938. Further trials were performed in Lithuania, from January 26th to March 11th of 1939. The tank drove for 1474 km.

The result was a successful light tank, somewhat superior to the PzII in characteristics.

As trials continued, the worldwide political situation became more and more heated. Meanwhile, CKD tried to get other Baltic states interested in their new tank. The LTL never made it to Tallinn or Riga, since there was a risk of losing the contract. The tank returned to Prague, where it met German occupation.

It's worth noting that the Germans did not impede the Lithuanian contract. The reworked tank was named Praga LLT. Instead of Maxim guns, it used Czech ZB vz. 37 machineguns, and the commander's cupola was moved to the right. The tanks would have been delivered in three batches of seven tanks, but Lithuania was annexed by the USSR on August 19th, 1940. A storm of letters was exchanged between local authorities and the Red Army GABTU, and there was even a brief search to find these tanks.

Swiss success

Even though the deal with Lithuania didn't pan out, there was another country willing to buy Czechoslovakian light tanks: Switzerland. The history of its armoured forces was similar to that of Lithuania. In 1921, the Swiss bought two Renault FT tanks, which received registration numbers M+7310 and M+7314. They served until 1940, although it was fairly obvious that they were unsuitable for mountainous terrain.

Two Carden-Loyd Mk.VI tankettes were purchased in 1930. Cooperation with Vickers-Armstrongs Limited continued, and two 4-ton Vickers-Armstrongs Light Tank Model 1933 were purchased in 1933. A year later, four more Vickers-Armstrongs Light Tank Model 1934 were ordered. In the Swiss army, they were called Panzerwagen 34/35. There were no further orders. The Swiss decided to pursue more modern vehicles, and to produce them domestically, not just buy them.

Switzerland's powerful arms industry was capable of producing tanks. Initially, the plans were to buy or build 80-90 tanks by 1939. In April of 1937, these appetites cooled down: six divisions were going to receive an armoured platoon of four tanks each, or 24 tanks in total.

Preliminary design of the Praga LTL-H.

The Swiss purchasing commission spent April 15th to 22nd in Essen, at the Krupp factory. The Germans had very little to offer aside from the PzI and the L.K.A./L.K.B. tanks, export tanks on its chassis. The Swiss departed for Stockholm. On their first visit, they tried out the Landsverk L-60. However, neither the L-60 nor the lighter L-120 was satisfactory for the Swiss. Perhaps they were just browsing.

Interestingly enough, Sweden itself had its eye on foreign tanks in the past, and visited Essen themselves in January-February of 1937. In March, the Swedish commission visited Prague and tested out the Praga AH-IV and Praga THN. As a result, the Swedes bought the Praga AH-IV-Sv tankette. These tankettes were assembled partially from Swedish components (armour, engines) and armed with Swedish weapons. This kind of flexibility at CKD, as well as good technical characteristics and low price, interested the Swiss.

An attachment to Aleksey Surin's patent on a special system that prevented burning fluid from entering the tank.

In mid-June of 1937, Emil Oplatka, a representative of CKD, received a letter from Captain Koenig, the head of the KTA's tank department (the technical department of the war ministry, Kriegstechnische Abteilung). Koenig was interested in the precise characteristics of the Praga AH-IV-Sv. Oplatka arrived in Bern on July 21st, where he had a meeting with Koenig. The head of KTA's tank department was interested by Oplatka's proposals. A Swiss delegation to Prague was planned. CKD began reworking the AH-IV for Switzerland. The company received permission from the Swedish military and from the Czechoslovakian Ministry of Defense to show Swedish materials to the Swiss.

In early September of 1937, the KTA's leadership arrived in Prague, where it viewed CKD's tanks. By the end of the month, the AH-IV-H tankette was designed, very similar to the AH-IV-Sv. Its price, depending on the production volume, was estimated to range from 345,000 to 383,500 Czech kroner. The project didn't last long; trials of British light tanks by the KTA made them realize that tanks of this size are too small to cross serious obstacles.

Swiss delegation in front of the Praga LTL-H. Captain Koenig is in the middle, in the leather coat.

On October 18th, 1937, the Swiss military formulated requirements for a new tank. They were very similar to the ones that the Lithuanians had. The mass of the tank was capped at 6 tons, the armour was to be 25 mm thick, and the armament consisted of Maxim guns and a 20 mm Oerlikon autocannon. The tanks would also carry a Saurer diesel engine. 

The similar requirements and existing designs for the Praga LTL meant that the work only took 5 days. The tank named Praga LTL-H was very similar to the Praga LTL visually, but the drive sprockets and transmission returned to the front of the tank. The turret was borrowed from the Peruvian Praga LTP.

Unlike the Lithuanian project, which dragged on, the LTL-H was developed very quickly. In November, CKD received permission from the Ministry of Defense to sell a license for this tank. Two contracts were prepared by early December. The first contract, #15430, was for 12 tanks at a price of 600,000 Czech kroner apiece. The cost did not include optics or armament. According to the second contract, #15431, Switzerland received permission to produce 12 more tanks under license. The agreement also included CKD's help in assembling the tanks. The contracts were negotiated in Prague on December 6th, 1937, and finally signed in Bern on the 18th.

Praga LTL-H during trials, spring of 1938.

The production of the first experimental Praga LTL-H happened just as quickly. Work was at its peak by the end of January of 1938. Despite the fact that the tank was supposed to have a Saurer diesel engine, the prototype had a Swedish Scania-Vabis 1664 engine. Work was slightly late, and the experimental LTL-H only began trials on March 17th, instead of February. KTA officers, including Koenig, observed.

The tank that entered trials was somewhat different from the initial project. First of all, the turret was changed noticeably. Instead of a gun, it carried a wooden dummy. In addition, it had an interesting feature. Information about battles in Spain reached Czechoslovakia, including frequent use of Molotov cocktails. To protect the engine from incendiary fluid, Surin designed a special "skirt'. Thanks to it, the fluid didn't spread across the fenders, but dripped off the back.

After completion of the first stage of trials, during which the tank traveled 811 km, additional minor changes were made to the LTL-H. The experimental prototype was sent to Switzerland, where it traveled another 901 km. After that, the LTL-H was equipped with a new engine: the 110 hp Saurer CT1D, initially designed for buses. The tank drove for another 750 km with this engine.

The Swiss military was satisfied with the tank, which showed itself well in the mountains. After completion of the trials, the LTL-H returned to Prague, where it was disassembled and re-equipped with the Scania-Vabis 1664 engine.

Like other CKD tanks, the LTL-H had good mobility.

In June of 1938, documentation for assembly of the LTL-H arrived at the KTA. Armour plates, observation devices, suspension elements, and transmission components arrived from Czechoslovakia. Everything else was built in Switzerland. Meanwhile, changes were still being made to the tank. The tank received a new turret with an air intake in the rear, like the Praga LTP.

One of the reasons for a redesigned turret was a change in requirements for armament. By mid-1938, it was obvious that the 20 mm Oerlikon 1S was obsolete as an anti-tank gun. It could not even penetrate the front armour of the tank that it was installed on.

In 1938, under the direction of Johann Adolf Furrer-Kägi, the chief designer at Waffenfabrik Bern, a 24 mm semiautomatic cannon was developed. It was built in two variants: tank (Panzerwagen Kanone 1938) and anti-tank (Panzerabwehr-Befestigungskanone 38). Thanks to a magazine feed, the rate of fire reached 30-40 RPM. The magazine also caused an issue: since it fed from the top, an indentation in the turret roof had to be made.

The idea of installing a 24 mm gun was a correct one. It had worthy penetration characteristics, and its rate of fire was higher than that of a 37 mm gun.

24 mm  Pzw-Kan 38 (Panzerwagen Kanone 1938) gun that was installed on mass production Pzw 39 tanks.

The events of September of 1938, when a war nearly broke out between Germany and Czechoslovakia, had its impact on the Praga LTL-H. The first sets of armour plates arrived at CKD from Kladno in October, and the first two tanks were ready for factory trials in mid-December. The first traveled 150 km, the second 1500 km.

Tanks built in Prague received Swedish gasoline Scania-Vabis 1664 engines instead of diesel ones. This included all 12 LTL-H tanks from the first batch. Koenig and other officers that arrived for an inspection were satisfied, and the tanks were sent to Switzerland. Deliveries continued even after the occupation of Czechia. Since Switzerland, much like Sweden, had tight ties with Germany in the military sphere, the Germans did not impede further cooperation.

The initial look of the Panzerwagen 39.

In parallel with production of tanks in Prague, components to assemble tanks in Switzerland were also built. The K+W (Eidgenössische Konstruktionswerkstätte) factory in Thun, close to Bern, was chosen. The city was home to the design bureau and proving grounds. Thun became the heart of Swiss tank building.

Assembly work was delayed, since the armour arriving from Kladno suffered from its traditional defects. In addition, some plates had to be replaced completely. An engineer was sent from CKD to correct defects. The Swiss also ordered spare parts from the company, now called BMM, many times. Despite all the issues that were uncovered during assembly, the tanks finally entered service in early 1940.

A column of tanks in three-colour camouflage.

In May of 1939, the first tanks began arriving in Swiss units. They were indexed Panzerwagen 39, or Pzw 39. By September of 1939, six tank platoons were organized. Each received 4 tanks, as planned. Registration numbers depended on what platoon the tank was in. The number 75 meant the mass (7.5 tons), the third number was the number of the platoon, and the fourth was the number of the tank in the platoon:
  • 1 platoon: M+7511 — M+7514
  • 2 platoon: M+7521 — M+7524
  • 4 platoon: M+7541 — M+7544
  • 5 platoon: M+7551 — M+7554
  • 6 platoon: M+7561 — M+7564
  • 7 platoon: M+7571 — M+7574
The number of the platoon corresponded with the number of the division that the tank was in.

The monochrome gray paint was quickly replaced a two-colour camouflage. Large letters CH were painted on the sides of the turrets so there could be no mistake that this was a Swiss tank. Some tanks, including tanks from the 5th platoon, had three colour camouflage.

Each platoon also had its own emblem on the side of the tanks. The first platoon had a lobster, the second had playing cards, the fourth had a snake, the fifth had a turtle, the sixth had a rhinoceros, the seventh had a crocodile. The tanks took part in Swiss army exercises in 1940 bearing these markings.

Despite their neutrality, the Swiss treated the fighting nearby very seriously. Denmark's neutral status didn't help that much. Nevertheless, the mountains would have slowed the Germans down. In addition, it was risky to stick their hand into a country famous not only for its mountains, but for international banks. Switzerland, just like Sweden, managed to preserve its neutrality during the entire war.

The letters CH signify that the tank is Swiss, and the crocodile means that the tank belongs to the 7th platoon.

Swiss tank units were reorganized in December of 1940. The tanks were combined into three companies of 8 tanks each. The first company had playing cards as its emblem, the second had a rhinoceros, and the third had a turtle. Later, one of these tanks became a test subject for various experiments.

Overall, the Swiss army was satisfied with its tank specifically and Surin's designs in general. It's not surprising that the Pzw 39 lasted in the Swiss army for many decades. The last order for spare parts was made in 1947, which allowed the tanks to serve for a while longer. In August of 1948, the tanks were removed from the tank companies, and replaced with G-13 tank destroyers. The Pzw 39 was finally retired in 1960.

Pzw 39 in the late 1940s. G-13 tank destroyers are seen in the background.

Careful treatment of these tanks meant that nine Pzw 39 survived until today, more than a third of all tanks built. You can familiarize yourself with the vehicle on display at Thun in this walkaround. At least three tanks are still functional. In 2016, one Pzw 39 tank was gifted to the Czech Republic, and this tank can be seen at the technical museum in Lešany. Knowing the skill of local restorers, we can be sure that, soon, this tank will also be back on its feet.

1 comment:

  1. Great article!
    Just a small comment, the walkaround pictures cover a tank in Full, not Thun: