Editing Stridsvagn 103 (section)

== Design ==
[[File:Strv 103 Hull Down Position (GMSF.010843).jpg|thumb|right|The Strv 103 in a "hull down" position presents a very low profile compared to conventional, turreted tank designs.]]
Studies of casualty reports from World War II and the [[Korean War]] revealed that the risk of being hit in combat was strongly related to height, with more than half of tank losses being the result of the turret being penetrated. Berge therefore concluded that any new design should be as low as possible.{{Citation needed|date=June 2022}} The radical solution was to eliminate the turret, which would also dispose of a vulnerable target area and make the tank much lighter. In terms of absolute height, the final design did not give the Strv 103 any significant advantage over its most likely opponent, the [[T-62]]. The latter was just slightly taller with {{convert|2.20|m|ftin|abbr=on}} in height with its turret versus the {{convert|2.14|m|ftin|abbr=on}} of the Strv 103. On the other hand, the [[Centurion (tank)#Sweden 2|Swedish Centurions]] towered over both with their {{convert|2.94|m|ftin|abbr=on}} – {{convert|3.01|m|ftin|abbr=on}} in height. However, the T-62 paid for its low profile with an extremely cramped interior and lack of gun depression. Tanks are often deployed in [[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 and 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 {{convert|13|cm|in}} by adjusting the suspension.{{Citation needed|date=June 2022}}

[[File:Strv 103 Suspension Gun Elevation Control (GMSF.010838).jpg|thumb|right|Strv 103 demonstrating its hydropneumatic suspension system and gun elevation.]]
Being familiar with both the French [[Char B1#Char B1|Char B1]]'s precision transmission, the exceptional turning performance of the short tracked assault guns, and the combat performance of the German [[Sturmgeschütz|StuG]] and [[Jagdpanzer]] series inspired Berge's design to solve the aiming problem through the use of a fully automated transmission and suspension system, which precisely turned and tilted the tank under the gunner's control. The gun itself would be fixed to the hull.<ref name="Lindström">{{cite web |url=http://ointres.se/strv_103.htm |language=sv |title=Historien bakom Strv 103 "S" |last= Lindström |first= Rickard O. |date=26 January 2012 |access-date= 8 December 2019 |quote=Redan 1943 hade han läst i en tysk tidskrift om franska försök 1940 med en vagn som hade en grovkalibrig kanon lagrad i chassit vid sidan av föraren. Försöken, med utgångspunkt i stridsvagnen Char B, visade att riktning av vagnspjäsen i sidled kunde göras hydrostatiskt med hjälp av bandrörelser – överlagringsstyrning.<br /><br />Sven kunde också dra sig till minnes vad det korta bandstället på stormkanonvagnarna medförde för sidriktmöjligheten. Han hade själv varit med och utvärderat den tyska surplusmaterielen som köptes in till Sverige efter kriget och blivit fascinerad av tyskarnas tornlösa vagnar av typ Sturmgeschütz eller Jagdpanzer – vagnar som togs fram snabbare och billigare än de vanliga tornstridsvagnarna utan att det gjordes avkall på vare sig eldkraft, rörlighet eller skydd.}}</ref> This made it impossible to use a stabilised gun. As a result, the tank could not accurately move and fire at the same time, but the Swedish experience with Centurions suggested that, in order for tanks to reach acceptable accuracy, they would need to come to a halt anyway, and wrongly{{synthesis inline|date=June 2022}} estimated that no breakthrough in stabilisation technology was likely within the foreseeable future.

Other features of the tank were also quite radical. The rifled gun, a Bofors 105&nbsp;mm L74 with a barrel length of 62 [[Caliber (artillery)#Barrel length|Caliber]]s, was able to use the same ammunition as the British [[Royal Ordnance L7]], and would be equipped with an [[autoloader]] allowing a rate of fire of one round every three seconds, 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), with one person being able to handle all functions of the tank from the ordinary position due to duplicate controls. This would of course only be used in emergencies, as the workload would be overwhelming, but apart from providing redundancy it also allowed the crew to shift tasks between them as situation required. The concept went through practical tests, that quickly revealed that a two-man crew would not be self-sufficient when considering the many tasks not directly related to handling the tank: in particular, routine maintenance, bivouacking, track-changes and reloading in field. While the last issue could have been solved by adding staff to the ammunition crews, it was decided that a third crew-member was needed. To enhance combat effectiveness, the third man was to be assigned as a rear driver/radio operator, facing the rear of the tank and 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, while relieving the commander of routine radio duty. The commander and gunner/driver both had the same set of sights and controls to fire the gun and drive the tank.

{{multiple image|caption_align=left
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 | image1 =Stridsvagn 103 Revinge 2013-3.jpg| width1 = 3704| height1 = 2047
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 | footer =A Stridsvagn 103C demonstrates gun elevation and depression using suspension, Revingehed, Sweden, 2013
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The tank was uniquely powered by two different kind of engines, a {{convert|240|hp|kW}} [[Rolls-Royce K60]] [[Opposed-piston engine|opposed-piston]] diesel for slow cruising and manoeuvring the tank in aiming, and a {{convert|300|hp|kW}} [[Boeing T50|Boeing 502 turbine]] for more power when travelling at higher speed or in severe terrain. The turbine was quickly found to be underpowered, and was replaced by a [[Caterpillar Inc.|Caterpillar]] turbine delivering {{convert|490|hp|kW}} after no more than 70 tanks had been produced, and retrofitted to all previous vehicles. 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.

The Strv 103 could be made 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 {{convert|6|km/h|mph}} in water.{{Citation needed|date=June 2022}}

One tank in each platoon was fitted with a [[Bulldozer#Blade|dozer blade]] under the front hull, which was from outside the tank manually dropped and locked into working position with pins and support struts. The blade allowed it to do simple engineering tasks, like digging fire pits for the platoon, filling trenches for ease of passage and so forth. Once the task was completed, the blade was again manually returned to the position under the front hull and locked in place. Upon the introduction of the 103C model all tanks had a bulldozer blade fitted, both to speed up operations and for the increased protection of the lower hull.