Stridsvagn 103

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Stridsvagn 103
Stridsvagn 103 Revinge 2013-1.jpg
Stridsvagn 103C
Type Amphibious Main battle tank
Place of origin Sweden
Service history
In service 1960s - 1997
Used by Swedish Army
Production history
Designer Sven Berge
Designed 1956
Manufacturer Bofors AB
Produced 1967 - 1971
Number built 290
Variants A, B, C, D
Specifications
Weight 103 B: 39.7 t (43.8 short tons; 39.1 long tons)
103 C: 42.5 t (46.8 short tons; 41.8 long tons)
Length 9 m (29 ft 6 in) (incl. gun)
Width 103 B: 3.60 m (11 ft 10 in)
103 C: 3.80 m (12 ft 6 in)
Height 2.14 m (7 ft 0 in)
Crew 3 (Commander, gunner/driver, rear driver)[1]

Armor 90-100 mm
Main
armament
Bofors 105 mm L/62 rifled gun
with 50 rounds
Secondary
armament
two fixed 7.62 mm KSP 58 machine guns
one anti-aircraft 7.62 mm KSP 58 machine gun
Engine

103 A: Rolls-Royce K60 diesel, 240 hp (179 kW) and Boeing GT502 gas turbine, 300 hp (223 kW)
103 B: Rolls-Royce K60 diesel, 240 hp (179 kW) and Caterpillar 553 gas turbine, 490 hp (365 kW)

103 C: Detroit diesel 6V53T, 290 hp (216 kW) and Caterpillar 553 gas turbine, 490 hp (365 kW)
Power/weight 18.3 hp/tonne (B and C)
Transmission 2 forward and 2 reverse speeds
Suspension Gas-hydraulic hydropneumatic suspension
Operational
range
390 km (240 mi)
Speed 50 km/h (31 mph) maximum road[1]

The Stridsvagn 103 (Strv 103), [Note 1] also known as the S-Tank,[Note 2] was a Swedish post-war main battle tank.[2] It was known for its unconventional turretless design, with a fixed gun traversed by engaging the tracks and elevated by adjusting the hull suspension. Turretless armoured fighting vehicles are usually classified as assault guns or tank destroyers, but the Strv 103 is considered a tank because of its gun laying ability and its designated combat role matches those of other tanks. It is the only main battle tank and the only tank of any kind since the World War II era to dispense with a turret.

The Strv 103 was designed and manufactured in Sweden. It was developed in the 1950s and was the first main battle tank to use a turbine engine. The result was a very low-profile design with an emphasis on defence and heightened crew protection level. Strv 103s formed a major portion of the Swedish armoured forces from the 1960s to part of the 1990s, but have since been removed from service in favour of the Stridsvagn 122.

History[edit]

In the mid-1950s, the Swedish Army put out a contract tender for a new tank design to replace their Centurions. A consortium of Landsverk, Volvo and Bofors responded with a suggestion to revive an earlier domestic heavy tank design, known under the codename KRV, fitted with a 155 mm smoothbore gun in an oscillating turret. However, this was deemed too expensive and the army started looking at British, German and American tanks.

Then, in 1956, Sven Berge of the Swedish Arms Administration proposed Alternativ S, a domestic alternative (S standing for Swedish). Noting that the risk of being hit in combat was strongly related to height, he proposed that any new design should be as low as possible. The only practical way to do this was to eliminate the turret (which would also make the tank much lighter and simpler), though in terms of absolute height, this still did not give the Strv 103 any significant advantage. Its most likely opponent, the T-64, was only 2.2 m (7 ft 3 in) in height with its turret versus the 2.14 m (7 ft 0 in) of the Strv 103 (a mere 3.5 inches lower). However, the T-64 paid for its low profile with an extremely cramped interior. Tanks occasionally deploy themselves into hull-down firing positions, either behind dug entrenchments or using the crest of a hill, in order to reduce the exposure of the vehicle to enemy fire. In this firing position the level of exposure is determined by the distance between the bottom of the gun barrel to the top of the turret or vehicle, and the angle to which the vehicle is able to depress the gun barrel. Since the Strv 103 orients the entire tank to depress and elevate the barrel, in a hull down position it has very little apparent height and subsequent visual profile to the enemy. It could also lower the hull a further 13 cm by adjusting the suspension.

Berge's design solved the aiming problem through the use of a fully automated transmission and suspension system, which would precisely turn and tilt the tank under the gunner's control. The gun itself would be fixed to the hull. This, of course, made it impossible to use a stabilized gun. As a result, the tank could not accurately move and fire at the same time, but the experience with Centurions suggested that, in order for tanks to reach acceptable accuracy, they would need to come to a halt anyway, and that no breakthrough in stabilisation technology was likely within the foreseeable future.

Other features of the tank were also quite radical. The gun, a Bofors 105mm L/62, was able to use the same ammunition as the British 105 mm L7, and would be equipped with an autoloader allowing a rate of fire of 15 rounds/minute, also allowing the crew to be reduced to two; a gunner/driver and the commander (most designs of the era used a crew of four). There was room for an extra crew member, a rear driver/radio operator, who faced the rear of the tank equipped with a complete setup for driving. This allowed the tank to be driven backwards at the same speed as forwards, keeping its frontal armour pointed at the enemy.

The commander and gunner/driver both had the same set of sights and controls to fire the gun and drive the tank. Additionally, the tank was powered by two engines, a 240 hp Rolls-Royce K60 opposed-piston diesel for slow cruising and manoeuvring the tank in aiming, and a 300 hp Boeing 502 turbine for additional power when travelling at higher speed or in severe terrain. The turbine was quickly found to be underpowered, and was soon replaced by a Caterpillar turbine delivering 490 hp, with the more powerful turbine also being retrofitted to all vehicles with the 300 hp turbine. This was the first use of a turbine engine in a production tank; the Soviet T-80 and US M1 Abrams would later be built with gas turbines for main propulsion.

The concept was interesting enough that Bofors was asked to build a prototype of the suspension/drive train, which they completed successfully. In 1958, a follow-on contract called for two production prototypes, which were completed in 1961. By this point, the army was so satisfied with the design that an initial pre-production order for 10 was placed in 1960. With minor changes, the Alternativ S was adopted as the Stridsvagn 103 ("103" from being the third tank with a 10 cm gun accepted into Swedish service). Full production started in 1967 and ended in 1971 with 290 delivered. The changes included a new gyro-stabilised commander's cupola armed with a 7.62mm KSP 58 machine gun, and upgraded frontal armour. A unique grid could be mounted at the front to help defeat HEAT rounds; however, it was kept secret for many years and was only to be fitted in the event of war.

The Strv 103 was fully amphibious. A flotation screen could be erected around the upper hull in about 20 minutes, and the tracks would drive the tank at about 6 kilometres per hour (3.7 mph) in water.

One tank in each platoon was fitted with a blade under the front hull that allowed it to dig itself into the ground for added protection.

The Stridsvagn 103 never saw combat and so its design remains unproven. However, for its intended role in the 1960s, it had numerous advantages. In 1967, Norway carried out a two-week comparative observation test with the Leopard 1 and found that, with closed hatches, the 103 spotted more targets and fired faster than the Leopard though the situation was reversed when operating with hatches open. In April to September 1968, two 103s were tested at the British armour school in Bovington, which reported that "the turretless concept of the "S"-tank holds considerable advantage over turreted tanks". In 1973, the BAOR tested the 103. British crewmen received 6 weeks training and the vehicles were serviced by Swedish engineers. Over nine days of manoeuvres alongside the Chieftain tank, availability never fell under 90% and the final report stated, "It has not been possible to prove any disadvantage in the "S" inability to fire on the move."[3] In 1975, two 103s were tested at the American armour center at Fort Knox. The trial demonstrated that the 103 fired more accurately than the M60A1E3, but on an average 0.5 seconds more slowly.[4]

Stridsvagn 103B[edit]

Strv 103C at the Swedish Army Museum, Stockholm, with anti-HEAT grid on the front.

As the weight of the Strv 103 had increased compared to the pre-production tanks, the 103 turned out to be underpowered. Hence, a more powerful version of the same gas turbine, manufactured by Caterpillar, was introduced after the first production run of 80 tanks. The early version (retroactively designated Strv 103A) was soon upgraded to B-standard.

Stridsvagn 103C[edit]

An upgrade programme was started in 1986 to fit all vehicles with improved fire control systems. Also, each Strv 103 was fitted with a dozer blade, rather than just one per platoon. A further upgrade in 1987/88 replaced the Rolls-Royce engine with a newer 290 hp (216 kW) Detroit Diesel with additional fuel tanks, and added a new laser rangefinder. There was some consideration of adding both reactive and/or appliqué armour in the early 1990s, but, in the end, the Strv 103 was instead phased out of Swedish service in favour of the Stridsvagn 122 (Strv 122), which entered service in 1997 (the last year that the Strv 103 was used to train tank crews).

Stridsvagn 103D[edit]

In the mid-1990s, as the Swedish Armed Forces were looking for a new main battle tank, one Strv 103C was upgraded into the Strv 103D. The major changes were the installation of fire-control computer, thermal viewers for both the gunner and the commander, allowing the crew to fight at night-time and in bad weather conditions, and the installation of passive light enhancers for driving. Some minor changes to the suspension system and engine were also made.

This prototype was used during the trials for the new main battle tank system for the Swedish Armed Forces alongside all the other tanks tested. For a few years this prototype was even tested under remote control. The only Strv 103D ever built is today on display at the Axvall armor museum,[5] together with some 103C models. They are all still in running order.

See also[edit]

References[edit]

Notes
  1. ^ "Strv" is the Swedish military abbreviation of Stridsvagn which means tank in Swedish.
  2. ^ from the procurement name, see history section.
Citations
  1. ^ a b Bovington Tank Museum
  2. ^ chant, c & Jones, R (2004). Tanks: Over 250 of the World's Tanks and Armoured Fighting Vehicles. Summertime Publishing Ltd. p. 156. ISBN 0-7603-1871-9. Retrieved 9 February 2011. 
  3. ^ http://home4.swipnet.se/~w-42039/comparisons_with_turreted_tanks.htm
  4. ^ militaryphotos.net[unreliable source?]
  5. ^ "Pansarmuseet". Pansarmuseet.se. Retrieved 2012-07-31. 
Bibliography

External links[edit]