Light Amphibious Scout Tank
Another area in which British designs had a strong influence on early Soviet tank types was the developmem of amphibious light armoured vehicles. The series of tank types bought from Vickers-Armstrong / Carden Loyd in 1929 had included the innovative VCL (Amphibian) Amphibious Tank. A light 3.04 tonne (3 ton) vehicle with a machine gun, it could cross small waterways. The Amphibian inspired a generation of Soviet Amphibious Tank designs, until the demands of war terminated production.
In 1931 a design team at Zavod Nr 47 near Moscow simultaneously developed two prototype Amphibious Tank which were based on the VCL design. The T-33 (originally designated the MT-33) had a crew of two and weighed 3.04 tonnes (3 tons) (read also tanks in action). The T-41 was similar in design and armament, carrying a single, turret mounted DT 7.62mm (0,3in) machine gun, with the main difference being in the body, which was slightly larger for greater buoyancy when crossing a waterway. Unsatisfactory performances during trials of the two vehicles, and especially problems with the T-41's waterproofing and the unsuitability of the VCL suspension, led to the development of a further alternative prototype.
The T-37 was a refinement of the earlier models rather than a radically new design. A modified Horstmann spring coil suspension was adopted with improved tracks and drive system for the single propeller. The hull was strength ened and sheet-metal track guards encasing balsa-wood floats were added for extra buoyancy. These modifications were dispensed with as the T-37 came to the end of its production run in 1936. Waterproofing problems persisted because of the hull's river construction, bur this was on the whole overcome in 1935 by welding together and riveting the tank's Soviet armour plates.
The durability of the T-37 design was shown during rigorous trials in 1933 when over 11 days, 7 T-37s travelled 1126 km (700 miles), over 965 km (600 miles) in water. Like most Soviet tank designs. dedicated command variants were constructed. which were termed T-37TU. A production run of 1200 vehicles was completed between 1933 and 1936. They served in a reconnaissance role with tank, mechanized and cavalry units in all Red Army operations up to 1942.
Plans to modernize the T-37 in the mid-1930s led to such extensive changes by the Zavod Nr 37 team that it was decided to designate it T-38. In proved hull design gave a lower profile and a decrease in weight. Coupled with a new suspension, wider tracks and improved steering, the T-38 was easier to handle, more manoeuvreable, and altogether a better swimmer than the T-37. Armament, however. remained the same as the T-37, although a 20mm (0,78in) gun fitted in a low turret with the driver was rejected because it restricted his ability to control the vehicle.
In addition to its reconnaissance role, the T-38 underwent several experimental combat roles. During the 1936 Kiev Military District manoeuvres, a number of T-38 and T-27 vehicles wcre air-landed deep behind enemy lines in a radical test of the potential of airborne forces. In 1940, several T-38s were adapted for radio control and fitted with explosives for use against enemy bunkers. An estimated 1300 vehicles were manufactured between 1937 and 1939.
Common to many pre-war Soviet tank designs. the T-37 and T-38 proved to be too vulnerable to heavy machin e-gun fire and shell splinters. This problem had been foreseen as early as 1938, when a special research departament at Zavod Nr 37, led by chief engineer N.A. Astrov, was instructed to design two variants of a new light scout tank, of which one was to be Amphibious Tank. Several prototypes of the amphibious vehicle (initially designated T-30A) were in trials between July and August 1939. Once orders to rectify defects were complied with, the vehicle was accepted for production and service as the T-40 on 19 December 1939.
The vehicle had a torsion suspension and, in the water. was driven by a single propeller and steered by two rudders at the rear. A more powerful engine, hermetically sealed hatches and a better-shaped front with a special water deflector enabled the T-40 to cross wider rivers with strong currents, like the Dniepr and Dnestr (although as a precaution the crew were supplied with lifebelts). Despite ambitious plans, production was low, and in 1940 the addition of extra armour and the need to increase tank production led to the non-amphibious T-30B prototype being given priority, also as the T-40.
At 6.09 tonnes (6 tons), both T-40 variants weighed twice the weight of the T-37 and T-38, but the cause of this increase - welded thicker 14mm (0,5in) bulletproof armour - did not make it any less vulnerable in battle to light weapons than they were. The inability of its 12.7mm (0,5in) DShK main gun, while firing armour-piercing rounds, to penetrate armour 16mm (0,62in) above 300m (984ft) also restricted its combat worthiness. Possibly if the T-40 had been used in its reconnaissance role, its Soviet armour and gun might just have proved sufficient, but the tendency of Soviet commanders to use them like regular tanks led to heavy losses in 1940 and 1941.
LIGHT TANKS OF WORLD WAR II
Scepticism about the ability ro manufacture the projected T-50 light tank and poor performance of the T-40 led N.A. Astrov's Zavod Nr 37 team ro develop a new light tank which would be capable of rapid production in order to satisfy the Soviet Union's desperate need for tanks after catastrophic losses in summer 1941. They retained the suspension, chassis and engine of the T- 40, but a new hull with an improved silhouette and an increased armour protection of 25mm (0,98in) frontal was designed. A distinctive eightsided conical turret that was cheaper to manufacture than the T-40's was also developed. The ineffective 12,7mm (0,5in) gun was retained with a co-axial DT 7,62mm (0,3in) machine gun.
The basic design was completed by the Zavod Nr 37 team in an amazing 15 days. Having created the T-60 concept on his own initiative, Astrov, seconded by Lieutenant-Colonel V. P. Okunev, wrote to Josef Stalin contrasting the advantages of mass-producing the T-60 with the more complex T-50. The following inspenion by a high-ranking minister resulted in two decisions. First to replace the 12,7mm (0,5in) machine gun with a 20mm (0,78in) ShVAK, an improvement over earlier light tanks, but still inadequate against the standard German Panzer III and IV models that the T-60 would have to engage whilst a shortage of medium T-34 tanks persisted into 1942. Second, the Main Defence Committee (GKO) headed by Stalin ordered production of 10,000 T-60s to commence immediately. Some sources claim that Stalin's interest in the T-60 was so great that he actually attended the vehicle's final trials in person.
Displacement of Soviet industry to the east in 1941 disrupted production and further refinement of the T-60. In Autumn Zavod Nr 37's move east saw work on the T-60 transferred to Zavod Nr 38 at Kirov and GAZ at Gorki. Soon afterwards, additional industrial evacuation left GAZ as the sole developer. Modifications made by that company in 1942 included an increase in frontal armour to 35mm (1,37in). The increased weight from the new armour exacerbated the T-60's sluggish performance characteristics, most notably its inability to keep up with the T-34 on cross-count by operations. A series of modifications failed to remedy this shortfall (read also The Red Army).
Installation of the GAZ-203 engine gave the T-60 theoretical speeds of 44km/h (27,3mph) by road and 22km/h (13,6mph) across country, but the latter was difficult to achieve and sustain. Replacing the spoked roadwheels on the1941 model with disc wheels, as well as the enforced adoption of an all metal construction because of rubber shortages had no real impact. Mobility over marshy- and snow covered terrain was enhanced by the development of removable track extensions, but again, they could not solve the difficulties of cooperating with T-34s. Similar attempts to up-gun the T-60 with the 37mm (1,46in) ZiS-19 and 45mm (1,77in) ZiS-19BM guns proved abortive because of the tank's small turret. By the time a redesigned turret capable of mounting the 45mm (1,77in) ZiS 19BM gun had passed its trials, the project was cancelled because the new T-70 light tank had been accepted for service. When production switched to the T-70 during February 1943, a total of 6022 T-60 light tanks had been manufactured.
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