The Swiss Eidgenoessisiche Konstruktionwerkstaett 30-ton 1957 1st prototype or just called KW 30/57-I was a rather unique prototype, second of the KW-30 experimental serie that would lead to the Panzer 58, start of the Swiss main Battle Tank cold war lineage. Thuis model was sometimes called the "Indian Panzer".

Development

The KW 30/57-I was the Prototype of the Panzer 61, using the same parts and not a completely different tank. It was built by Federal Construction (K+W) of Switzerland. Its testing setup the groundwork for the Panzer 61. A second prototype was built in parallel, testing different parts and configurations. Both were also related to the preserie Panzer 58.

in 1950, the Swiss army started developing a 30-tonne medium tank called the KW 30. the prototype built in 1952, the tank was not successful. the development has been slowed down by the lack of industry and skills on the matter of how to build a modern tank, but the Swiss still knew what they needed. needing a tank with good firepower, mobility and protection while being at around 30 tonnes. the introduction of the Centurion and AMX 13 in the Swiss army did provide them with rather modern tanks, but neither of those tanks was adapted to the alpine road and cold mountainous terrain.

while the KW 30/52 was not accepted for services, the Swiss army went on with the development and developed the KW 30 model in 1957. this development started as soon as 1953 with the interest from India to build a tank for their own need (the Indian-panzer) this new prototype featured review armour, better gun elevation and the addition of a coaxial 20mm. the coaxial was an alternative to the main gun as it was capable of dealing with lighter targets without the need to use the main gun. two prototypes were built, one was armed with the local 90mm gun while the second was tested with a different turret. this new tank was a bit heavier and was closer to 35 tonnes, but remained well mobile. this model was built in 1957 but wasn’t accepted to services as the Swiss army was asking for more firepower, the 2nd prototype was favoured.

Design

Hull and general design

(To come)

Protection

The KW 30/57 was having a reviewed protection over the KW 30/52. the front of the hull was reviewed and rounded but retained the same thickness as the model from 1952 and was welded with 2 plates. the side armour was also reduced to 30mm but a sideskirt was added. the turret was the most improved with the frontal armour passing to 100mm and the side armour to 50mm but the rear was also reduced to 35 mm. The tank also received 6 smoke launchers which were to be launched 2 by 2.

Mobility

This tank has a bit heavier weight than the KW 30/52 but remains in the 30-tonne class. with 35 tonnes. this tank is still a decent medium tank for his time. featuring a new Mercedes-Benz MB 837 Ba-500, 29900cc, Diesel Supercharged V8, 600hp @2200rpm, it had more torque than the previous engine which was taken from the WW2 Tiger 1. The transmission was also changed to allow better mobility. with a new SLM Winterthur, 6F/2R, and Semi-Automatic transmission, the tank was much more mobile.

Armament

the main armament of this tank is a 90mm Panzerkanone 48 L/60. this gun may sound impressive at first due to its rather large size, but it is pretty average on the scale of an early cold war gun. the main ammunition is assumed to be a solid AP round which reduces a lot his effectiveness but gives it a rather decent penetration. the gun has good velocity and accuracy and a decent reload. it would be a pretty decent match against late WW2 tanks such as the IS-2 or Tiger II. the turret rotation is not well known, the fire rate should reach 10 rounds/minute in the best conditions. offering a decent -10° depression, it would be fairly comfortable in uneven terrain.

The elevation of 25° allows it to aim at the highest peak and even engage the aircraft that may be careful. the tank carries 48 rounds which is a 19-round improvement over the prototype. the main gun also features a huge coaxial with a 20mm Oerlikon 5TG. This Auto-cannon have a high fire rate of 600 round-minutes but only has a 120-round belt. a single additional belt is carried for the coaxial which gives it a total of 240 rounds. the coaxial has an independent elevation which allows a depression of -10° like the main gun but + 21° which is still good but less than the main gun. no LMG was ever installed on the prototype.

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KW 30/52 specifications

Dimensions: 9.7 x 2.9 x 2.55 m (31’9” x 9’6” x 8’4” ft)
Total weight, battle ready: 33 tons
Crew: 4 (commander/radio, driver, gunner, loader)
Propulsion: 600 hp (441 kW) Maybach Diesel engine, 18.18 hp/ton
Suspension: Torsion bar suspension
Speed (road): 45 km/h (28 mph)
Armament: 90 mm L/63 (3.5 in) gun, 20 mm Oerlikon coax. gun
Armor: 70 mm (2.75 in) front turret, 60 mm (2.36 in) front hull, 45 mm sides( 1.77 in)
Total production: 1 mockup and 1 prototype

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Sources

TE panzer-58-and-its-development
secretprojects.co.uk
forum.warthunder.com