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LostCosmonaut

The Swedish AFV Thread: Not Just Strv 103s

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Thanks to renhaxue for running the Swedish Tank Archives, where much of the information in this post came from.

 

 

The Strv m/42

 

 

strv_m42eh-5.JPG

(http://www.ointres.se/strv_m42eh-5.JPG)

 

The Soviet T-34 and American M4 were the quintessential medium tanks of World War 2, though many more were made. One of the less well known “other” tanks was the Swedish Strv m/42. Though it never entered combat, the Strv m/42 still had an important role in the Swedish Army for many years, and was an important milestone for AFV development in that country.

 

EarlyL60.jpg

(http://photos1.blogger.com/blogger/7632/1958/1600/EarlyL60.jpg. Ironically, the L-60 outlasted its descendants in military service, with the last Dominican examples not retiring until 2002).

 

 

Sweden’s development of the Strv m/42 was done under very severe constraints. In 1941, Sweden’s armor forces consisted mostly of variants of the L-60 light tank. Weighing less than 10 tons and only armed with a 20mm or 37mm gun, the L-60 was notably inferior to tanks like the T-34 or Panzer III. During the late 1930s, the Landsverk company had developed an improved version of the L-60 called the Lago. It was larger, with improved armor and a 47mm main gun. A variant with a 57mm gun was also considered. Though Landsverk developed the tank for export (specifically to Hungary), it did not get any takers.

 

However, in May 1941 (link: http://tanks.mod16.org/2014/01/08/minutes-of-meetings-with-the-armor-committee-of-1941/nggallery/image/540), the Swedish Army decided to develop a modern tank to supplement their L-60s and license built Lt vz. 38s. Weight was limited to 20 (later 22 tons); Swedish infrastructure (especially bridges) simply could not support a heavier vehicle. There were also limits on width, to ensure the new tank could be transported easily on the Swedish rail network. Since the tank needed to be ready for production in 1942, there was no time for a completely new design. Landsverk set about modifying their Lago prototype, stretching it and fitting a larger gun, while also improving the armor. This did not go entirely perfectly: the new design experienced problems steering due to its length. It was also quite liable to tip over.

 

QSRNfp6l.jpg

 

The Strv m/42 was equipped with a torsion bar suspension, like many other tanks of the time. In addition to the main armament (for which multiple alternative were considered), there were also four ksp m/39 (license built M1919) 8mm machine guns. Two coaxial with the main gun, one on top of the turret, and one in the front of the tank. Total crew complement was four soldiers.

 

Multiple armament options were considered for the Strv m/42. First was a 57mm gun, which is mentioned in the Swedish archives as having good anti-tank performance. I am not sure of the particulars of this gun, but it is probably comparable to the British 6 pdr or Soviet ZiS-2. While it would have been good at the antitank role, the 57mm would have been handicapped by low HE payload. The next option considered was a 105mm howitzer. This gun would have been very effective in the infantry support role, but poor against tanks. Additionally, rate of fire and accuracy would have been poor. The third option was a medium velocity 75mm gun. This option would offer adequate performance against current tanks, while also being good in the infantry support role. As a result, it was chosen.

The specific model of gun chosen was the 75mm m/41 L34 gun. The m/41 was a decent gun, broadly comparable to the 75mm M3 which equipped the American M4. However, it was somewhat handicapped by the Swedish Army’s desire to have the gun use existing artillery rounds; this reduced the Strv m/42s anti-tank capability. Later on in the tank’s life, there were numerous projects to upgun the m/42. The most notable of these was the fitting of a high velocity 75mm gun in a new turret; this project was known as the Strv 74. These tanks would serve until the 1980s. There were other projects which did not enter service, including the fitting of an automatic loading device.

lzohrf1.jpg

(Strv m/42 armor scheme, originally posted by sp15 on WoT EU forums)

 

Originally, it was planned to equip the tank with two Scania-Vabis engines, which would produce a total of 320 hp. However, politics intervened. The Strv m/42 was to be produced at the Landsverk and Volvo plants, and Scania was a main competitor to Volvo. Volvo was worried about how it would look to the civilian market (highly important even then) for them to build a tank powered by a competitors engine. As a result, some of the Strv m/42s (the EH variant) were built with a single Volvo engine, producing 380 hp. In all, about 220 tanks were built with Scania engines, and about 60 with Volvo engines.

 

As Sweden had not built a tank the size of the Strv m/42 before, there was not a domestically produced transmission which could handle the weight of the tank (simply reusing the transmission would have had catastrophic consequences for reliability (see also: Panther)). So the Swedes contacted someone who had a lot of experience building tanks; the Germans. The Germans sold the Swedish military the ZF electromechanical gearbox, an advanced design which was also quite light. Sadly, it was horridly unreliable. By 1944, nearly 2/3 of the ZF equipped tanks in one Swedish regiment were out of service. As a result, the Swedes were forced to make their own gearbox. After study of T-34s captured by Finland, Volvo was able to produce a hydraulic gearbox, which was fitted to Strv m/42s starting in 1944. Initially, it was fitted to new built EH and TV variant tanks, though it was eventually retrofitted to the entire Strv m/42 force.

 

b0i8Hwll.jpg

(A prototype of the Strv 74, via Swedish Tank Archives

 

The Strv m/42 in its base form served in the Swedish military from 1943 until 1957. At that point, it was replaced by the Strv 81 (Centurion Mk. 3), as well as the Strv 74. Some Strv m/42s were modified into Ikv 73 fire support vehicles, and in that guise they stayed in service until the 1960s. There were many projects to replace the Strv m/42 in the late 1950s and early 1950s, such as the Strv Leo and EMIL programs. However, none of them came to fruition. As far as I know, the Strv m/42 was never exported, or even considered for use by any other country. In the post-World War 2 climate, surplus M4s or T-34s would have been easily available for very cheap.  (I believe the Swedes even tried to obtain surplus M4s at some point, but were unable for some reason). Overall, while the Strv m/42 might not have been a world-beating tank, it was still a quite solid effort, especially for a nation’s first real attempt at building a tank in that weight class.

 

Further Reading:

 

http://tanks.mod16.org/tag/strv-m42/- Swedish Tank Archives pages on Strv m/42

http://ftr.wot-news.com/2014/04/18/swedish-tanks-part-vii-strv-m42/- Article on Strv m/42 in World of Tanks video game, written by sp15, has useful info

http://www2.landskrona.se/kultur/landsverk/militart/stridsvagnar/lago.html

 

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npxDYke.jpg

UQ1C16f.jpg

TXbYPiJ.jpg

7bULIbW.jpg

Strap twenty 10,5 cm recoilless rifles to the back of a truck in 1944, what do you get? Rocket artillery, without the rockets! Of course, to try to fool spies they called it "spare gun barrel carrier, provisional model 1943" (reserveldrörsvagn fm/43, a vehicle so obscure it is literally ungoogleable, at least until now). Later entered service as 10,5 cm salvkanon m/46, but AFAIK only four vehicles were ever manufactured.

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swiss-armor-page-1.jpg

swiss-armor-page-2.jpg?w=700&h=&crop=1

swiss-armor-page-3.jpg?w=700&h=&crop=1

swiss-armor-page-4.jpg?w=700&h=&crop=1

Oh for fuck's sake, you all are way too polite.  I just realized I posted an entire article on Swiss tanks in a thread on Swedish AFVs and nobody called me out on it.  I am a fucking retard.  

 

For my next trick, I should probably post an article on the Australian Sentinel tank in a thread on Austrian armor. 

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Oh for fuck's sake, you all are way too polite.  I just realized I posted an entire article on Swiss tanks in a thread on Swedish AFVs and nobody called me out on it.  I am a fucking retard.  

 

For my next trick, I should probably post an article on the Australian Sentinel tank in a thread on Austrian armor.

I was like "surely he must be joking"

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How effective was this side 'armor'?

I only have one report to go off (in a test rig, not on an actual tank, with the plastic jerry can between 35 and 80 cm from the armor plate) but the results with three different types of 60's vintage HEAT rounds are as follows. Max measurable penetration in this test is 310 mm.

If the can is empty: no measurable effect. Different rounds behave differently depending on fuze type, though: rounds from pskott m/68 (disposable launcher, expected penetration ~310mm RHA) and pvpj 1110 (9 cm recoilless rifle, expected penetration 325mm RHA) detonate when hitting the can, rounds from Carl Gustav (8,4cm recoilless rifle, shape-stabilized round with long probe fuze, expected penetration 350mm RHA) go through the can and detonate only when hitting the armor plate in three cases out of four.

If the can is filled with water: fucks with the fuzing on the Carl Gustav rounds, two out of three rounds fired failed to detonate and the third did something weird (the results table says "chock ignition, point of impact warm" with no further explanation) resulting in no measured penetration. The pskott m/68 and pvpj 1110 rounds detonate normally when hitting the can but penetration is reduced roughly 25-50% from the expected values - there is a lot of variation though, especially in the pvpj 1110 case.

These rounds all have a listed penetration in the 300-350mm RHA range though so even reducing it by 50% isn't nearly enough to prevent a penetration of the actual side armor.

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Yeah, some of the UDES concepts were pretty bonkers. I also seem to remember at least one other Swedish AFV concept with an articulated setup (or maybe I'm just remembering a pic of something towing its own ammunition trailer).

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Yeah, I forced my way through the HEMLIG Swedish documents that article is talking about, no mention of using an AMX turret there. Also, contrary to what anyone would assume about WG's M/42 57 based on the name, that is actually supposed to be a 75mm gun according to previous Rita posts

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It is a 7,5 cm gun. Strv m/42-57 (tank model 1942, modernized version of 1957) was the internal working name for what would become the strv 74. They needed a new turret to fit a long 7,5 cm gun instead of the stubby peashooter the m/42 had, so four options were investigated:

A.1 was a conventional turret (this option was chosen for the historical strv 74)

A.2 was an oscillating turret, AMX 13 style

A.3 was trying to make an earlier turret design actually work (the "split turret")

B was abandoning the re-turreting idea and rebuilding the chassis to a casemate TD.

So this option was actually kinda-sorta considered for a short time in the early 1950's. It's unclear if they actually intended to just buy or license produce AMX 13 turrets though; personally I believe the intention was to design and produce a domestic turret. Whatever, this is good enough for WoT.

When the m/42 was being developed they did consider a long-ish 57 mm gun for it but it was considered insignificantly better at armor penetration than the short 7,5 cm.

I'm doing research for the Swedish tree on Wargaming's behalf (as a consultant) and while I'm under an NDA, I'll try to answer any questions you might have re: the rationale behind making the choices we did.

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