The Strv 103, also called the S-Tank, is Sweden's trademark tank. A lack of turret, fixed gun with an autoloader, active suspension, three driver positions (one per crewman), these are only some of its unusual features. Swedish tank designers managed to surprise the world. However, the Strv 103 didn't come out of nothing, and a significant portion of the components that went into the tank came from experimental vehicles. How did Sweden assemble this industrial "Lego set"?
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Showing posts with label S-Tank. Show all posts
Showing posts with label S-Tank. Show all posts
Saturday, 25 February 2017
Friday, 12 February 2016
Turretless Swede: Strv S
In the mid-1950s, Swedish tank building was at a crossroads. The Swedish military needed a tank that was most appropriate for the local theater of war. This tank had to be small and light, have a powerful gun, good armour, and the ability to quickly move around the battlefield.
Swedish tank designers spent a lot of time working on a heavy tank known as the KRV. The result was an unusual vehicle that would have had a 155 mm gun with an automatic loading mechanism in the turret, similar to the French AMX 50. The design was too heavy and too expensive, and only experimental chassis with no armament were built. It turned out to be cheaper to buy Centurion Mk.3 tanks from the British, adopted as Strv 81. However, the Centurions did not entirely satisfy the military. These tanks were about as large and heavy as the KRV, and even later Strv 101 (Centurion Mk.10) tanks with an improved 105 mm L7 gun did not entirely satisfy firepower requirements.
Sven Berge headed a project for a new tank. The first blueprints are dated 1956, and by 1957, three new potential designs were ready:
Swedish tank designers spent a lot of time working on a heavy tank known as the KRV. The result was an unusual vehicle that would have had a 155 mm gun with an automatic loading mechanism in the turret, similar to the French AMX 50. The design was too heavy and too expensive, and only experimental chassis with no armament were built. It turned out to be cheaper to buy Centurion Mk.3 tanks from the British, adopted as Strv 81. However, the Centurions did not entirely satisfy the military. These tanks were about as large and heavy as the KRV, and even later Strv 101 (Centurion Mk.10) tanks with an improved 105 mm L7 gun did not entirely satisfy firepower requirements.
Sven Berge headed a project for a new tank. The first blueprints are dated 1956, and by 1957, three new potential designs were ready:
- Strv A: 42.5 tons, well armoured, with a loading mechanism, comparable in size with the American M60, and rather slow.
- Strv T: 32.5 tons, similar to the Leopard 1 in design. Effective power was about 25-30 hp/ton, armour was no greater than 75 mm.
- Strv S: a completely new concept of a turretless tank. Its combat mass was estimated at 30 tons and it had extremely good protection due to its low silhouette.
The S design was picked as most suitable. Work started in that same year on elements of this new tank that were tested on various vehicles. In 1959, a KRV prototype with one road wheel per side removed and a 105 mm gun in the front was tested. Experience gained while working on the KRV was applied as much as possible on this project.
By 1961, the outline of the new tank formed. A fully sized wooden model was built, and the first prototype was finished a while later, the Strv S1. It was mostly a test bed for the tank's chief feature: an active suspension, which allowed the tank designers to leave out a vertical aiming mechanism. In addition, the tank could "crouch down", which is very important in Swedish terrain. The Strv S could hide behind a small stone wall, which are still a very common sight in Sweden.
The Strv S2 was ready by the end of 1962. The second prototype was no longer a test test bed, but a fully fledged fighting vehicle that implemented all new ideas from the turretless tank. This prototype was armed with a 105 mm L7 gun, later replaced with a 105 mm L/62 Bofors gun. The gun was equipped with an autoloader. Initially, a remote controlled machinegun turret was planned for the Strv S, but the Strv S2 did not have it. On later vehicles, it was replaced with two machineguns in the front of the hull.
The tank was equipped with a Rolls-Royce K60 engine and a Boeing GT502 gas turbine. The front armour was only 40 mm thick, which seems quite little, but it's enough to see what angle it's positioned at, and all complaints disappear. The mass production tank, indexed Strv 103, was also amphibious. Buoyancy was achieved using a system similar to the Duplex Drive, designed by Nicholas Straussler. Overall, the result was an interesting and original fighting machine, adapted to the region in which it was going to fight.
Two experimental Strv S tanks survive to this day. The tank that this article is dedicated to sits at an entrance to the base of an army unit south of Karlsborg. Since the base is active, access to the tank is restricted to weekends only. Another prototype spent a lot of time at a scrapyard for Swedish military vehicles. In late September of 2015, the tank took up an honourable spot neat the Beredskapsmuseet museum near Helsingborg. The two prototypes differ slightly, but not even Swedish historians know which one is an S1 and which one is an S2. During installation, some removable parts of both vehicles were lost, and air intakes welded shut.
The Strv S differs not only from the mass production Strv 103, but even from the pre-production batch of vehicles. Even the shape of the hull is somewhat different. There is a characteristic "step" on the right side, behind which the muffler is placed. A large headlight sits in the center of the tank, with smaller indicators on the sides (the indicators only remain in the rear part of the tank). The machineguns were supposed to be on the left side of the upper front plate. The box containing them was lost, but you can see where it used to be attached to the tank.
On the left side, the Strv S is similar to the production vehicle, but there are still many differences. The rear is the most distinct. In addition, there is a cutout near the drive wheel which is absent on production tanks.
Initially, the Strv S had a 105 mm L7 gun, later replaced with a longer 105 mm Bofors gun. This gun is currently installed on both prototypes.
The rear plate migrated to production tanks without changes. Wide hatches are present to load ammunition. A small hatch is present at the top to eject spent casings.
A characteristic part of the Strv S is the lower front plate with wide mud scrapers in front of the tracks. The final drive covers also bulge noticeably. In the pre-production batch, the mud scrapers were removed, and the bulges were reduced in size. The tow loops also migrated from the upper front plate to the lower, as they were interfering with fording equipment.
According to the official version of events, the Strv S suspension largely reuses components from the KRV, but this is not so. Only tracks were reused. The drive wheels and idlers were made from scratch, and road wheels were taken from the Centurion tank. Aside from simplicity of production, this decision was inspired by a drive for parts unification.
The track links migrated without change from the KRV tank. Pre-production tanks had a new track link with a rubber pad, more suitable for use on paved roads.
The production Strv 103 upper front plate has little in common with the Strv S. The prototypes shared its gun placement design and the general idea of engine access hatches, as well as the machinegun placement. Large hatches to the left and right of the gun provided access to the engines, in the production version, the hatches are much smaller. Another sign of it being a prototype is the vision devices placed in the connection between the upper front plate and the roof.
The roof also has several major differences. The crew placement, and therefore the position of the hatches, is the same, but otherwise there are many differences, especially in the rear.
The commander's cupola was borrowed from the Pbv.301 APC. Initially, it was to be used without changes, including the 20 mm M/45B autocannon. The autocannon was present on the model, but the Strv S1 did not have it. The commander's cupola migrated to the pre-production batch of Strv 103s, but was later replaced with an improved version.
Another tell-tale sign of the Strv S is the presence of separate hatches for driver and his assistant. In the first Strv 103s, these hatches were replaced with one big one with a clever system for closing and opening it.
Detailed photos of the Strv S exterior can be seen here. (click the mauve arrow on the right side of the screen)
Thursday, 9 April 2015
Modern Tank Off-Road Trials
Odds are you've seen the Swedish cross-country tank trials of the Sherman, Panther, and Strv m/42 and read about various similar trials here and here. Now, watch the modern T-80U, Centurion, and S-Tank effortlessly (well, mostly) tear up the obstacles their ancestors could not dream of conquering.
Part 1: T-80U vs Centurion in fall conditions.
Part 1: T-80U vs Centurion in fall conditions.
Part 2: T-80U vs Centurion vs S-Tank in winter conditions.
Saturday, 4 April 2015
Swedes on Britain's Armoured Forces
Today's article is once again brought to you by Something Awful forums poster TheFluff, who discovered some critique of the British Army on the Rhine (BAOR). Swedish observers who were present during the exercises held in 1973 were rather unkind.
"The gunnery practice was finished by two tests with a gun camera, one against a fixed target and one against a moving one, as per usual Swedish standard. The results were bad. The first time the results may possibly be explained by the gunners not taking the trial seriously, but even after they had evaluated their own results and re-did the test the results were very bad. It is possible that more training could have improved the results somewhat, but the more likely explanation is that a large portion of the British gunners simply aren't suited for their job as gunners. In some cases, problems with bad eyesight were apparent. It should be noted that British tank personnel is not tested in the same way as Swedish personnel before being assigned as tank gunners."
"Both the methods the tank crews used for engaging targets and their laying skills were unacceptable and clearly worse than that of the average Swedish crew."
On observation and crew resource management:
"The number of targets detected was on par with the performance of Swedish crews. However, the time to open fire was in most cases far longer than can reasonably be expected. In part, this is due to lack of training on the tank, but more importantly it's also due to the way the British crews work together. The tank commander always have to give orders about everything and the gunner is forbidden from opening fire on his own initiative when he spots a target, unlike in Swedish regulations for tank crews. Just like in the 1968 trials, it has been impossible to convince the Brits to try the Swedish method, which is also employed by the Germans for example. The reason cited by the Brits is that tanks carry so few rounds that the commander cannot risk the gunner opening fire on a non-essential target and that the gunners in general aren't all that good at neither judging the importance of a target nor at adjusting their fire. (...) This severely limited the advantages of the S-tank's duplicated controls.
(...)
Nor were the Brits willing to accept the principle that whoever sees a target first fires on it. If the tank commander spots a target, the gunner should still open fire on it. According to Swedish tests, if the commander has to hand the target over to the gunner, the time to open fire is on average two seconds longer than if the gunner opens fire by himself. If questions regarding the target's exact position are raised, this time increases further, up to 10 seconds or more in many cases. Our proposal to try the Swedish method in parallel with the British was rejected without any reason given."
On tactics:
"(in a discussion on delaying fights) The target marker equipment made this exercise an excellent and very illustrative example of how not to fight this type of action (in both Chieftain and the S-tank)."
"Coordination between infantry, artillery and tanks is nonexistent.
(...)
The infantry is deployed way too late to take terrain from which the enemy can fight the tanks with close-in AT weapons.
(...)
The assaults are not planned in depth. On the first day it took seven hours to advance seven kilometers, employing 17 tanks and a mechanized infantry platoon against an enemy with 9 tanks and a mechanized infantry platoon, deployed in three lines."
More on the exercise:
"The BLUFOR tank units appear very unprofessional. Uses unsuitable formations, roads and combat positions. In general, they appear to think they are invulnerable. Tank commanders and loaders stand very far up in their hatches. Drivers have hatches open and drive with their head above the edge.
There is no coordination of attacks between tanks, infantry and artillery. Tanks attack alone into forests. Infantry attacks alone across open fields straight at defending tanks. When attacking, units are not concentrated, neither in space nor in time. Attacks are always conducted in a "trickling" fashion.
Radio traffic is very intensive but there are rarely orders given.
At the OPFOR, unit commanders are often deployed very far behind their units, battle group commanders about 5 km behind and combat team commanders 500-1000 meters behind.
CYCLOPS (the S-tank squadron) combat positioning during the delaying action was usually pretty good.
All tanks, both Chieftain and S-tanks, are driven very carelessly. No attention is paid to neither civilian traffic nor property damage. Reports on engine failures have a hard time reaching the maintenance units. Map reading capabilities are overall very bad.
(...)
The experiences from these exercises appear to be highly questionable."
"British tank crews always carry a lot of baggage, both combat and non-combat equipment (cooking equipment, food, tents etc), on and/or in their tanks. Unlike our crews, they are completely independent of separate cooking units and baggage trains. This meant that the space available in the S-tank was far too small for their equipment."
"Deployment width and depth is considerable in the smaller units. Tank platoons are often deployed over a width/depth of 600-800 meters. (...) Tank platoons are frequently deployed independently behind each other. Support is organized within the platoon and not between platoons. The rear platoon is usually 500-1000 meters behind the front one. Hence, the result is that the enemy knocks them out one by one, platoon after platoon. Both platoon commanders and tank commanders act very independently and choose both their own routes and positions and their own timings for advancing or repositioning. The whole thing frequently resembles a guerrilla war or every man for himself.
The infantry is used way too late to take terrain from which the enemy can fight the tanks up close with weapons such as recoilless rifles. The tanks attack first. When they start taking fire, the mechanized infantry is deployed. There is no planning for attacks in depth. On the first day, it took seven hours to advance seven kilometers with the BLUFOR's combat team (17 tanks and a mechanized infantry platoon) against an OPFOR with 9 tanks and one mechanized infantry platoon, deployed in three lines.
If a platoon or squadron commander's tank gets engine problems, the commanders do not move to another tank. Tanks are frequently deployed in very unsuitable positions where they are easily knocked out. The observation and recon duties are conducted badly. The soldiers seem very passive. Chieftains are often positioned behind a ridge with the gun and the chassis side against the enemy. The S-tank crews rarely clean their optics.
When fighting a delaying action, the tanks in a platoon retreat by turns along the whole depth of the deployment. Withdrawal is frequently started far too late, and the tanks are thus knocked out one by one. Despite the terrain allowing opening fire at long distances (2-3 km), fire is often opened far too late (500 m). There is never a rear platoon deployed to cover the front platoon's withdrawal.
In light of the heavy criticism above, it has been very hard to judge how well the S-tank has proven itself. The results have mostly been influenced by troop performance and and not by the tank's performance. As far as it has been possible for us to observe, though, we cannot say that the S-tank has suffered more losses than the Chieftains.
S-tank availability has been good. Most of the time all tanks have been in working condition in daytime. On the OPFOR side, the Chieftain availability has dropped steadily. Near the end of the exercise the availability was down to 50%, and thus a Chieftain platoon was transferred from BLUFOR to OPFOR."
"The gunnery practice was finished by two tests with a gun camera, one against a fixed target and one against a moving one, as per usual Swedish standard. The results were bad. The first time the results may possibly be explained by the gunners not taking the trial seriously, but even after they had evaluated their own results and re-did the test the results were very bad. It is possible that more training could have improved the results somewhat, but the more likely explanation is that a large portion of the British gunners simply aren't suited for their job as gunners. In some cases, problems with bad eyesight were apparent. It should be noted that British tank personnel is not tested in the same way as Swedish personnel before being assigned as tank gunners."
"Both the methods the tank crews used for engaging targets and their laying skills were unacceptable and clearly worse than that of the average Swedish crew."
On command style and discipline:
"Exercise of command was relatively tame and commanders rarely supervised anything. The subordinates were left with a lot of freedom to solve rather ill-defined problems on their own. When it came to looking after their equipment, the personnel was rather sloppy and nonchalant."
"The readiness (in a broad sense of the word) at the BAOR appears to be rather low."
"Radio traffic was very lively, but rarely contained orders."
"Exercise of command was relatively tame and commanders rarely supervised anything. The subordinates were left with a lot of freedom to solve rather ill-defined problems on their own. When it came to looking after their equipment, the personnel was rather sloppy and nonchalant."
"The readiness (in a broad sense of the word) at the BAOR appears to be rather low."
"Radio traffic was very lively, but rarely contained orders."
On observation and crew resource management:
"The number of targets detected was on par with the performance of Swedish crews. However, the time to open fire was in most cases far longer than can reasonably be expected. In part, this is due to lack of training on the tank, but more importantly it's also due to the way the British crews work together. The tank commander always have to give orders about everything and the gunner is forbidden from opening fire on his own initiative when he spots a target, unlike in Swedish regulations for tank crews. Just like in the 1968 trials, it has been impossible to convince the Brits to try the Swedish method, which is also employed by the Germans for example. The reason cited by the Brits is that tanks carry so few rounds that the commander cannot risk the gunner opening fire on a non-essential target and that the gunners in general aren't all that good at neither judging the importance of a target nor at adjusting their fire. (...) This severely limited the advantages of the S-tank's duplicated controls.
(...)
Nor were the Brits willing to accept the principle that whoever sees a target first fires on it. If the tank commander spots a target, the gunner should still open fire on it. According to Swedish tests, if the commander has to hand the target over to the gunner, the time to open fire is on average two seconds longer than if the gunner opens fire by himself. If questions regarding the target's exact position are raised, this time increases further, up to 10 seconds or more in many cases. Our proposal to try the Swedish method in parallel with the British was rejected without any reason given."
On tactics:
"(in a discussion on delaying fights) The target marker equipment made this exercise an excellent and very illustrative example of how not to fight this type of action (in both Chieftain and the S-tank)."
"Coordination between infantry, artillery and tanks is nonexistent.
(...)
The infantry is deployed way too late to take terrain from which the enemy can fight the tanks with close-in AT weapons.
(...)
The assaults are not planned in depth. On the first day it took seven hours to advance seven kilometers, employing 17 tanks and a mechanized infantry platoon against an enemy with 9 tanks and a mechanized infantry platoon, deployed in three lines."
More on the exercise:
"The BLUFOR tank units appear very unprofessional. Uses unsuitable formations, roads and combat positions. In general, they appear to think they are invulnerable. Tank commanders and loaders stand very far up in their hatches. Drivers have hatches open and drive with their head above the edge.
There is no coordination of attacks between tanks, infantry and artillery. Tanks attack alone into forests. Infantry attacks alone across open fields straight at defending tanks. When attacking, units are not concentrated, neither in space nor in time. Attacks are always conducted in a "trickling" fashion.
Radio traffic is very intensive but there are rarely orders given.
At the OPFOR, unit commanders are often deployed very far behind their units, battle group commanders about 5 km behind and combat team commanders 500-1000 meters behind.
CYCLOPS (the S-tank squadron) combat positioning during the delaying action was usually pretty good.
All tanks, both Chieftain and S-tanks, are driven very carelessly. No attention is paid to neither civilian traffic nor property damage. Reports on engine failures have a hard time reaching the maintenance units. Map reading capabilities are overall very bad.
(...)
The experiences from these exercises appear to be highly questionable."
The infantry is used way too late to take terrain from which the enemy can fight the tanks up close with weapons such as recoilless rifles. The tanks attack first. When they start taking fire, the mechanized infantry is deployed. There is no planning for attacks in depth. On the first day, it took seven hours to advance seven kilometers with the BLUFOR's combat team (17 tanks and a mechanized infantry platoon) against an OPFOR with 9 tanks and one mechanized infantry platoon, deployed in three lines.
If a platoon or squadron commander's tank gets engine problems, the commanders do not move to another tank. Tanks are frequently deployed in very unsuitable positions where they are easily knocked out. The observation and recon duties are conducted badly. The soldiers seem very passive. Chieftains are often positioned behind a ridge with the gun and the chassis side against the enemy. The S-tank crews rarely clean their optics.
When fighting a delaying action, the tanks in a platoon retreat by turns along the whole depth of the deployment. Withdrawal is frequently started far too late, and the tanks are thus knocked out one by one. Despite the terrain allowing opening fire at long distances (2-3 km), fire is often opened far too late (500 m). There is never a rear platoon deployed to cover the front platoon's withdrawal.
In light of the heavy criticism above, it has been very hard to judge how well the S-tank has proven itself. The results have mostly been influenced by troop performance and and not by the tank's performance. As far as it has been possible for us to observe, though, we cannot say that the S-tank has suffered more losses than the Chieftains.
S-tank availability has been good. Most of the time all tanks have been in working condition in daytime. On the OPFOR side, the Chieftain availability has dropped steadily. Near the end of the exercise the availability was down to 50%, and thus a Chieftain platoon was transferred from BLUFOR to OPFOR."
On the British vehicles:
"The Chieftain tank:
The reliability seems surprisingly low. During the exercises, the number of tanks that had to drop out due to mechanical trouble was relatively high. Mostly, it's the engine that is the problem. When a Chieftain stops, after a little while there's always an oil slick on the ground or garage floor under it. The gun stabilization also fails frequently. The accuracy of the contra-rotating feature in the commander's observation cupola is very low. It is almost never used by the Brits. The tank's speed over terrain does not seem to be superior to that of the S-tank. The commander's observation equipment is very good.
The Scorpion tank:
The Swedish personnel got an excellent briefing on the tank and was also allowed to drive it. It is very fast and easy to drive. The observation equipment is absolutely excellent. (...)
The FV 432 APC:
Appears to have a large number of different reliability problems, mainly concerning the steering gears. The vehicles are so far gone that they are considered a danger to traffic. According to maintenance personnel, a lot of the problems are caused by the soldiers not doing sufficient daily maintenance."
"The Chieftain tank:
The reliability seems surprisingly low. During the exercises, the number of tanks that had to drop out due to mechanical trouble was relatively high. Mostly, it's the engine that is the problem. When a Chieftain stops, after a little while there's always an oil slick on the ground or garage floor under it. The gun stabilization also fails frequently. The accuracy of the contra-rotating feature in the commander's observation cupola is very low. It is almost never used by the Brits. The tank's speed over terrain does not seem to be superior to that of the S-tank. The commander's observation equipment is very good.
The Scorpion tank:
The Swedish personnel got an excellent briefing on the tank and was also allowed to drive it. It is very fast and easy to drive. The observation equipment is absolutely excellent. (...)
The FV 432 APC:
Appears to have a large number of different reliability problems, mainly concerning the steering gears. The vehicles are so far gone that they are considered a danger to traffic. According to maintenance personnel, a lot of the problems are caused by the soldiers not doing sufficient daily maintenance."
On civilian relations:
"Very little attention is paid to the fact that the unit is exercising on private property. Careless driving on public roads and the maneuver area isn't delimited. Damage to planted fields is frequent despite good opportunities to choose routes over fields where the harvest has already been taken in. Apparently the property damage costs for a similar exercise in the same area last year were on the order of 10 million SEK (about 62 million SEK today, ~6 million EUR). These damages are paid for by the German authorities."
"Very little attention is paid to the fact that the unit is exercising on private property. Careless driving on public roads and the maneuver area isn't delimited. Damage to planted fields is frequent despite good opportunities to choose routes over fields where the harvest has already been taken in. Apparently the property damage costs for a similar exercise in the same area last year were on the order of 10 million SEK (about 62 million SEK today, ~6 million EUR). These damages are paid for by the German authorities."
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