Saturday, 27 May 2017

Renault NC: Destined for Export

The Renault FT ended up being not only the best tank of WWI, but the most numerous one. Its production continued after the end of the war, and 3728 tanks were built by 1921. Meanwhile, the French army was no longer satisfied with the Renault FT. Even the infantry, which inherited the tank, was not thrilled with a vehicle that had a top speed of 3 kph off-road. To replace this "pensioner", Renault designed a new tank called the Renault NC. Why were foreign armies more interested in this tank than the French?

Path of least resistance

Aside from reliability issues with rapidly ageing tanks, serious financial issues influenced further development. Even though Renault specialized in cars and trucks, it did not want to lose its income from military orders. The end of the Great War meant that funding was reduced. Renault could no longer expect the completion of the order for 3940 tanks. On the other hand, a number of countries started local wars, and the combatants needed weapons, including tanks. Here, the French army stood in the way of Renault as an exporter, as they gave away their tanks left and right. The company either had to satisfy itself with miserly order volumes or seek new solutions.

An additional problem with the Renault FT was that its miserly speed meant that trucks were required to move it any significant distance. Trials showed that the engine began to overheat at higher speeds. Even installing a more powerful engine did not help, as the semi-rigid suspension limited the top speed. In addition, the running gear of the tank, especially the tracks, had very poor reliability, only 150-200 km. In order to fix the tank's mobility issues, these problems would have to be solved.

A suspension patent that Adolphe Kégresse used on halftracks and modernized Renault FT tanks.

Meanwhile, the former chief of the technical unit of the Imperial garage, Adolphe Kégresse, returned from Russia in 1917. Here, he began to promote the most important invention of his life: a tracked suspension with a rubber track. André Citroën, the founder and head of a well known automotive company that started its business in the military sector, was intrigued by this invention. Kégresse began working for Citroёn in 1919, as they moved from ammunition to automobiles. The halftrack system, which was perfected with the help of engineer Jacques Hinstin, proved successful. Citroёn-Kégresse halftracks became famous. They were used by the French Army, and armoured cars were built on their chassis.

Renault FT with a Kégresse suspension in Morocco. Obstacle crossing rollers were already added.

Kégresse offered to design a similar solution for the Renault FT, riding the wave of his success. An order was made for 26 of these tanks, which were made in 1925. The armament, turret, hull, and engine remained unchanged. The tanks were converted from existing Renault FTs. 

The old suspension was removed, replaced with a suspension that was very similar to the one used on early Citroёn-Kégresse halftracks. Two four-wheel bogeys were used on each side. The tracks were fully metallic. As the mass was greater than that of halftracks, the track and drive sprocket had to be changed. The resulting tank is often called Renault NC M24/25, but that index was never used in reality.

Tanks modernized after battles in Morocco. As you can see, the rollers were not installed on all tanks, and they could be armed with either machineguns or cannons.

Modernized tanks were sent to the 508th Tank Regiment, where they were organized into two companies. Military trials began, which included exercises in Mourmelon, home to one of the French army's central training facilities. Immediately, a small issue was discovered. Even though the suspension was longer, the tank occasionally scraped its hull against obstacles. To prevent this, rollers were attached to the front of the hull. Trials showed that the replacement of the suspension was a good idea. The top speed increased with the same engine, and the range was also increased.

Yugoslavian tanks on parade. The rear rollers can be seen.

It's possible that the trials could have been completed successfully, and the equipment of Renault FT tanks with Kegresse's suspension would have been commonplace, but fate played a cruel trick. In the summer of 1925, France officially joined Spain in the Rif War in Morocco. The tank unit equipped with Kegresse's tanks was among those sent to fight. Their rubber tracks were quickly worn down by the rocky terrain. One of these breakdowns ended tragically on October 3rd, 1925. While trying to fix the track, the tank's crew was killed by Berbers. Four more tanks lost their tracks in that battle. Since Kegresse's track was made out of one piece, it was difficult to install.

A tank with a modernized suspension in Poland. A decision was made to buy 5 such tanks.

After returning from Morocco, the tanks were sent to Versailles, where they were repaired and modernized. The track had to be changed drastically. Rubber-metallic grousers were added, which improved off-road traction. Modernized tanks continued serving in the 508th BCC. The track design,tested on the modernized Renault FT was later used on other Citroёn-Kégresse vehicles.

Deep Modernization 

When Kegresse's work on the Renault FT was just starting, the French army began thinking about seriously changing the tank. The Germans managed to obtain specialized anti-tank guns towards the end of WWI. Even though their penetration was a lot less than of the guns available in the early 1930s, they had no issues with tanks of the era. In addition, tanks started carrying armour piercing shells, which could penetrate up to 15 mm of armour. More protection was needed.

Renault NC-2 on the factory floor.

In 1923, an order for two modernized tanks was made, indexed Renault NC at the factory. The military, as well as Renault, decided to play it safe, in case Kegresse's suspension doesn't prove itself. The prototypes, indexed NC-1 and NC-2, had identical turrets and hulls, but different suspensions. Development went slowly, and the tanks entered trials in 1925.

The Renault NC-2 used Kegresse's suspension. Issues discovered during its use on the Renault FT were corrected. The bogey and suspension design remained largely the same, as well as the idlers. The drive sprockets were replaced, as insufficient traction was observed. The road wheels were also changed, and now had rubber rims. The track was altered, and now it was stretched out, without return rollers. This kind of solution raises many questions about how easy it would be to use in battle. Stretching out the tracks on a Renault FT with Kegresse's suspension was already hard, and the process of doing it with the NC-2 was even harder.

Close up view of the Renault NC-2's suspension.

The alternative was the Renault NC-1. Considering its number, looks like Renault placed their bets on this design. Turns out they made the right choice. This tank had metallic track links, but the design was altered. The rest of the suspension was changed even more. As with the NC-2, the tank had four wheels per bogey. However, while Kegresse's design used leaf springs, the Renault design had vertical coil springs. The result allowed for a larger contact surface.

The number of road wheels was insane for a light tank: 14 per side, two of which were used to soften the impact when hitting an obstacle. The drive sprocket and idler were fully redesigned. The suspension was covered up with shields to protect it from mud.

Renault NC-1 prototype.

Both prototypes had identical turrets, borrowed from the Renault FT. The hull was also similar to that of the Renault FT. This was not caused by conservatism on behalf of Renault, but by the French army, which wanted to save money. The war was over, the country was recovering from four years of bloodshed, and money for new toys was hard to come by, especially considering how many Renault FT were already in service. The front was identical to that of its predecessor, except for an increase to 25 mm of armour. This armour protected the tank from heavy machineguns. The rear was redesigned completely, to fit a new 62 hp engine. Since it was larger than the Renault FT's engine, the engine compartment had to be lengthened.

Renault NC-1 on trials, which showed that a traditional suspension was still better than Kegresse's design.

Trials, which began in 1925, showed that both tanks were superior to the Renault FT. Even though the increase in armour raised the mass of the tank from 6.7 to 8.5 tons, the new engine and superior suspension meant that both new tanks could reach a speed of about 20 kph. For an infantry support vehicle, this was enough. Trials also showed that a rubber-metallic track lost out to the a traditional design. The trip of Renault FT tanks with Kegresses's suspension to Morocco also happened around this time, which resulted in an even more negative evaluation.

As a result of the trials, the NC-1 emerged as a clear leader. The French army could get a modern tank, superior to the Renault FT in most ways. However, in 1926, infantry command composed new requirements for a light tank. Its mass had to be about 13 tons, the armour was increased to 30 mm, and the 47 mm cannon was proposed as armament. The Renault NC did not meet any of these criteria. There was some hope with cavalry, but that branch was not interested either.

In this situation, Renault had no other choice but to offer the tank for export. It received the index NC-27. It is sometimes claimed that the NC-2 was marketed for export as the NC-31, and these vehicles were built for China, but this is incorrect. The NC-2 remained as a single prototype.

Renault NC-27 on trials in Poland.

The first buyer of NC-27 tanks was Poland, which ordered one tank in 1928. The tank was tested alongside the Renault FT with the Kegresse suspension. After lengthy trials, the Poles declined a large purchase. They already had over 150 Renault FT tanks, and the new ones were not a sufficient improvement to cause significant interest. The order was limited to one NC-27 and five Renault FT with Kegresse's suspension, which received new tracks. These tanks were known as M26/27.

Renault got luckier with another buyer: Yugoslavia. According to various sources, either 9 or 10 Renault FT tanks with Kegresse's suspension were purchased. They survived until the spring of 1941, when the Germans invaded Yugoslavia. By that time, the obsolete tanks could not do much on the battlefield and were easy prey. Some of them were knocked out, a few were captured intact. One of them eventually ended up in American hands and was sent to the Aberdeen Proving Grounds.

According to François Vauvillier's research, the tanks that were sent to Yugoslavia and Poland were called Renault FT-Kegresse, and 29 were made, not 26. As for the Renault M. 24/25, Renault M.26/27 and Renault NC-31, these tanks were invented in the Tanks encyclopedia, which was published in 1935 in Munich. Published as a spiritual successor to Heigl's book (Fritz Heigl died in 1930), it contained a large number of inaccuracies and straight up inventions. 

For example, the NC-27 is recorded under the index NC-31, and the NC-2 is really the experimental NC-3, which later became the D1. The authors claim that the NC-2 was used in Greece and Japan, which is incorrect, as is information about the Renault M.26/27 that were allegedly sent to China. Due to a lack of other sources, these mistakes are often repeated by authors.

This photograph illustrates the outcome of the trials of the NC-27 in Sweden.

Sweden was another country that took an interest in French tanks. At the time, German and Austrian engineers were working on convertible drive tanks for Sweden. However, development was dragging on, forcing the Swedish army to seek an alternative. One NC-27 was purchased in 1928. The Swedish army indexed it Strv fm/28. Trials went badly from the very start. The gearbox and clutch were not particularly reliable. To make things worse, the suspension was poorly suited for Sweden. The results of the trials meant that no further purchases would be made.

On the other hand, the NC-27 finally convinced the Swedish army that tanks have to be developed locally and not bought elsewhere. The tactical-technical requirements for a new tank were composed after studying this tank. However, the vehicle ended up being useful for more than just trials. The Strv fm/28 served as a training tank for some time. Today, this tank can be seen at the Arsenalen tank museum, as the last surviving specimen from the NC family.

Fortune finally smiled upon the tank that was rejected by European nations. An order for 10 NC-27 tanks was made by the Imperial Japanese Army in 1929. According to Japanese sources, the deal was for 23 tanks. The tanks were shipped to Japan that year. It appears that the Japanese had the same opinion about individual components as the Swedes. However, they had little choice, since things were going poorly at the time. Japan had no domestically designed light tanks at all, and only 22 Renault FT tanks, purchased from France earlier.

Otsu-Gata Sensha, the Japanese modernization of the NC-27. The tank is equipped with the Japanese Type 11 37 mm gun.

The Japanese took it on to themselves to correct the drawbacks of the imported tanks. According to French sources, the tanks, indexed Type 89, received more powerful Mitsubishi engines. The 75 hp motor was enough to accelerate the tank to 20 kph. Some Type 89s received 6.5 mm Type 3 machineguns. The 37 mm SA 18 cannons were replaced with 37 mm Type 11 infantry cannons. The gun shared an ancestor with the SA 18: the French 37 mm mod. 1916 trench gun. However, it was more powerful, and could be used in an anti-tank role. As a result, the Type 89 was the most heavily armed tank from the Renault FT family.

Type 89 tanks with new guns and engines were the first tanks the Japanese army used in combat. On September 18th, 1931, Japanese intervention in Manchuria began. The battle for Harbin broke out in late January of 1932. In addition to the 2nd Infantry Division, the 1st Special Tank Company, commanded by Captain Hyakutake, also took part. However, there was no fully fledged battle at Harbin. Poorly trained Chinese forces quickly retreated, and the Japanese tanks had no worthy opponents. However, some conclusions were made from that experience. For example, the operational range of the French tanks turned out to be very short.

Combat in another part of China, Shanghai, began around the same time. Here, Captain Shigemi's 2nd Independent Tank Company took part in the fighting. The company contained five Type 89 tanks and ten NC-27 tanks. Combat showed that Japanese medium tanks were far superior to French light tanks. The NC-27 showed the same weaknesses that it did during trials in Sweden. The suspension was deemed unsuitable for this theater of war. The tanks were later sent to form the 1st Tank Regiment in Kurume. Here, the NC-27s were used alongside Type 89s as training vehicles.

Japanese NC-27 tanks during exercises of the 1st Tank Regiment in Kurume. The tanks are armed with either a cannon or a machinegun.

Despite the humble successes, it's hard to call the Renault NC program a failure. Although the tank was never accepted into service in France, and it success abroad was limited, these were the only mass produced French tanks of the 1920s. Further development of the Renault NC resulted in the mass produced D1, which even saw combat. The tank was noticed in other nations. For example, the Soviet experimental T-19 light tank used an NC-1-like suspension.

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