Posts Tagged: s-tank

Demonstration of the elevation system on the strv 103

I’m not perfectly sure but I don’t believe these are the full extents of the elevation system – the depression is probably close to the max but I think the elevation could go another couple of degrees. To add to your enjoyment, here are a few pictures from the manual that shows how the system works. “Kvävgas” means “nitrogen”, and “olja” means “oil”.

Oil is pumped from the front cylinder into the rear one, the rear swing arm is forced down and the tank depresses.

Oil is pumped from the front cylinder into the rear one, the rear swing arm is forced down and the tank depresses.

Oil is pumped from the rear cylinder to the front one, the front swing arm is forced down and the tank elevates.

Oil is pumped from the rear cylinder to the front one, the front swing arm is forced down and the tank elevates.

Schematic view of the strv 103 elevation system components.

Schematic view of the strv 103 elevation system components.

By the way, in case you ever wondered what the heck “elgon” means in Swedish and been unable to find out (the word isn’t in the Swedish Academy Dictionary and is basically ungoogleable), the appropriate English translation is synchro. Naturally, I mistranslated it at first, so where it says “resolver” in the schematic above, it should say “synchro”.

Report from British strv 103 trials at BAOR, 1973

In the summer of 1973, the British Army on the Rhine (BAOR) evaluated the strv 103B in the field. The crews were ordinary British tank crews from the 2nd Royal Tank Regiment, who were sent to Sweden to train on the 103 for four weeks. Ten tanks were then sent to Germany for several months worth of field trials. This report, authored by the Swedish observers from the Swedish Armored Forces School covers the results – such as they were – of these trials.

In general, the observers consider the results of the evaluation to be highly dubious at best. The trials were conducted in such a haphazard and unscientific manner that the results were considered mostly useless. The observers also devote a lot of space to scathing criticism of the BAOR. I’ve translated some of the more interesting passages below – it’s highly entertaining reader.

By request from a reader, I have provided the report as a PDF in addition to the ordinary image gallery.

The observers on the quality of British tank gunners

At the end of the gunnery training, there were 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 these 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 weren’t suited to 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.

(pg 15)

Both the methods the tank crews used for engaging targets and their aiming skills were unacceptable and clearly worse than that of the average Swedish crew.

(pg 15)

Swedish tank crews were conscripted. Tank crews were considered a particularly demanding position and the requirements for getting assigned to one were very high.

On crew resource management etc

The number of targets detected was on par with the performance of Swedish crews. However, the time from detection to opening fire was in most cases far longer than can reasonably be expected. In part, this is due to lack of training on the 103, 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 correcting their own fire.

(pg 14)

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.

(pg 14, pg 45)

These limitations in engagement methods severely limited the advantages of the strv 103’s duplicated controls.

On discipline and exercise of command

Exercise of command was relatively tame and commanders rarely supervised anything. The subordinates were left with a lot of freedom to complete rather ill-defined tasks on their own. When it came to looking after their equipment, the personnel was rather sloppy and nonchalant.

(pg 13)

On tactics

(in a discussion on fighting delaying actions) 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 strv 103).

(pg 85)

We would like to call some attention to the British regulations on deployment width for tank platoons. When deploying for defense, a platoon can be deployed over a width as great as 800 meters! Even during attacks, the width frequently reached 5-600 m. The combat simulation equipment often proved that these regulations are clearly inappropriate. The platoon rarely had any means of concentrating its fire and thus the enemy picked tanks off one by one. The British reasoning is “the enemy advances on a broad front and has many tanks, we are few but must cover the entire width”. The German liaison was horrified by this philosophy and the British conduct!

(pg 45-46)

On performance in major field exercises

The last part of the trials was conducted as a major field exercise. The BLUFOR had Chieftains only, the OPFOR mixed Chieftains and strv 103’s. The OPFOR “won”, but the Swedish observers dismiss the results as “highly questionable”.

The BLUFOR tank units appear very unprofessional. They use 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 strv 103 squadron) combat positioning during the delaying action was usually pretty good.

All tanks, both Chieftain and strv 103’s, 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.

When the exercises ends, 9 out of 10 strv 103’s are fully combat ready.

The experiences from these exercises appear to be highly questionable.

(pg 141-142)

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 strv 103 was far too small for their equipment.


Very little attention is paid to the fact that the unit is exercising on private property. Driving on public roads is very careless and the exercise area is not marked or 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. During this year’s exercises, five people died in accidents; during the same exercise last year, thirteen people died.

Strike aircraft are available on request during the exercises. Helicopters are used for both recon and command duties. The routines for coordinating with airplanes and helicopters seem to be well developed. The British command APC is well suited to its purpose and the space available is better than in our equivalent vehicle. Wired communications are not used between brigade staffs and battle groups. The system with call signs painted on the rear of the tanks appears to work well.


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 strv 103 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 strv 103 has proven itself. The results have mostly been influenced by troop performance and not by the tank’s performance. As far as it has been possible for us to observe, though, we cannot say that the strv 103’s have suffered more losses than the Chieftains.

Strv 103 availability has been good. Most of the time all tanks have been in working condition during the day. 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.

(pg 127-128)

On 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.

(pg 146)

Read the entire report in PDF form, or hit “Continue reading” to browse the photographed document images on this web page.

Archive reference: SE/KrA/0092/A/A2/001:H/F1-1974/35

Report from British evaluation of the S-tank (1968)

In 1968, the British army borrowed two brand new S-tanks from Sweden and subjected them to six months of various trials in Britain. This report is covers the result of those trials. Since it’s in English, I’m not going to summarize it further – read it yourself and draw your own conclusions. However, keep in mind that the S-tanks tested are very early models that are suffering from some teething problems.

If you want to pick cherries, here are some particularly interesting/entertaining pages to get started on:
page 97 (tank vs SPG discussion, etc)
page 132 (results from automotive trials)
page 142 (crew comments)

The report is also available in PDF form.

Archive reference: SE/KrA/0092/A/A2/005:H/01:H/F1/10

Report (May 1958) from the 2nd Equipment Planning Study Group

Original title: Rapport maj 1958 från studiegrupp 2 för fortsatt tygmaterielplanering

The 2nd study group for further equipment planning was responsible for figuring out what kind of requirements would be reasonable to expect from next-generation direct-fire AFV’s (tanks and APC’s, mostly) that were to enter service around 1965. In order to do this, the group considered what the Soviets were doing, what everyone else was doing, current bleeding edge research, where tank development was right now and where it was heading. In May of 1958 the group issued this report, which is a bit over 90 pages long.

The report discusses current trends in tank development, and designates three general lines of development called the A-tank, the T-tank and the S-tank.

  • The A-tank (A for America, probably) is the expected result from current US and UK design philosophy. It weighs about 40-45 metric tons and is frontally protected against sub-caliber kinetic penetrators fired from guns of up to 120 mm caliber, with mobility somewhat impaired by its weight. (In reality, this alternative later resulted in the M60 Patton and the Chieftain.)
  • The T-tank (T for Tyskland – Germany) is the expected result from current German and French design philosophy. It weighs about 30-35 metric tons and has very high specific engine power (25-30 hp/t or more), but only has frontal protection against (the equivalent of) 57 mm guns. (In reality, this alternative later resulted the Leopard 1 and the AMX-30.)
  • The S-tank (S for Sweden) is a proposed turretless Swedish design that has the same protection as the A-tank against kinetic weapons, while weighing only about 30 metric tons. Additionally, since the gun is fixed in the chassis, it can be fitted with screens or lattices that will protect it from all currently known anti-tank missiles and other HEAT penetrators.

The report then goes on to reason about the importance of low tank weight with regards to strategic mobility. For Swedish conditions, tanks should ideally weigh less than 37 metric tons. Based on this and other factors, the authors argue that the army should not purchase upgunned Centurions from the UK, as they are too heavy and an insufficient upgrade over the 84 mm variant. Instead, it is recommended that future Swedish tank development should focus on a) testing the S-tank concept in practice to see if it’s a workable solution, b) start development on a domestic A-tank equivalent (reusing the existing Krv chassis for experiments as necessary), using an autoloader instead of a manual loader to keep the weight down, and c) keep an eye on developments in the US and UK with the intention of purchasing complete tanks if something better/cheaper than the domestic alternatives comes up.

The report also features about a metric ton of appendices, which I have photographed but not published here because they are mainly used as support for the recommendations outlined in the main report and thus not really all that interesting on their own. If you see one you want in the table of contents, leave a comment and ask for it and I’ll post it.

Archive reference: SE/KrA/0266/002/01:H/F III/1

Memo regarding the future development of turreted tanks (1959)

A memo dated 1959-03-23, outlining the guidelines for future development of turreted tanks. The “A-tank” (the conventional turreted alternative to the S-tank, developed in case the hydraulic gun laying system on the S-tank would prove unworkable) is put on hold (and thus effectively cancelled, since the army ended up choosing the S-tank) and possibilities for putting a Centurion mk 10 turret on the Krv chassis is discussed. The latter is proposed as an alternative to purchasing the Centurion mk 10 mainly for economical and trade balance reasons, since it would mean building the tank in Sweden rather than purchasing it from the UK.

Archive reference: SE/KrA/0266/002/01:H/F I/32

Discussion and schematics of autoloaders for Strv A and Strv S

Three documents dated in January and February of 1959, discussing autoloader mechanisms for the two projected tank options of the time, the S-tank and the A-tank (the latter being a turreted tank of conventional design, cancelled at an early stage in favor of the S-tank).

Archive reference: SE/KrA/0266/002/01:H/F I/33

Preliminary plans for guns, autoloaders and ammunition for strv A and strv S

Two documents from 1958 describing early developments in tank gun specifications, intended for two alternatives for a future Swedish tank. The alternatives are called “stridsvagn typ A” and “stridsvagn typ S” where A is a conventional turreted design and S is a very early S-tank (at this point they haven’t yet decided if the S-tank’s hydraulic gun laying system is technically feasible or not, so they plan for both alternatives).

Archive reference: SE/KrA/0266/002/01:H/F I/20

S-tank: investigation regarding increasing the engine output

Memo (dated 1964-02-22) from Bofors regarding various possibilities in increasing the engine output of the S-tank. Options mentioned are a supercharged 275 or 300 HP version of the Rolls-Royce K-60 piston engine (a 240 HP version powered the first incarnation of the S-tank), a 300 HP Volvo piston engine in development for use on the pbv 302 APC and a Boeing 553 turbine.

Archive reference: SE/KrA/0266/005/01:H/F II/5

S-tank live fire trials

Watch this film clip to see an S-tank shot at, driven over minefields, exposed to simulated tactical nukes, strafed with aircraft guns and finally napalmed. Remember to enable English captions if you can’t understand spoken Swedish.

Why does the S-tank look like it does?

At the time when the first vague ideas about the S-tank started to take form (late 50’s), weapons technology was far more advanced than armor technology. It seemed prohibitively hard to design a tank that had sufficient protection against modern HEAT and APDS shells while also maintaining decent mobility and staying within reasonable weight limits. When the French and German governments cooperated on the Europa-Panzer project (what would become the AMX-30 and the Leopard 1), one of the stated design goals was to sacrifice armor strength in favor of mobility and weight savings. The British Chieftain was considerably better protected but especially in its early versions suffered from high weight and poor cross-country mobility.