Strv m/31 & Strv fm/31

[Sp15 266]

Welcome!
This thread is part of the Swedish tech tree project and one of the threads where i wil go more in depth with sources and information which i have not included in the main thread. As i said in the main thread im currently sitting on about 30 000 pages of information from the swedish war archive so if there is anything that is unclear please PM me and i will provide a source.

 

Strv m/31 & Strv fm/31

 

History

 

In October 1931 the Swedish army placed an order for 3 conventional and one wheel-XXX-track type tank from Landsverk. Internally these tanks would be referred to as L-10 and L-30 but they would be officially designated as Strv m/31 and Strv fm/31 by the swedish military. For the most part the L-10 and L-30 were designed to share the same layout and major components but with different suspensions.

 

Landsverk L-30

 

The L-30 improved on the wheel-XXX-track suspension of the Räder-Raupen Kampfwagen M28 GFK and featured a slightly narrower chassis compared to the L-10. The transition to wheeled mode took around 30 seconds and could be done while the tank was moving, in this mode the L-30 could reach a top speed of 80 kph on roads. However the heavier suspension didn’t allow for a satisfactory level of armor protection without breaking the 12 ton weight limit.

 

Landsverk L-10

 

The tracked suspension was identical between the two designs. By getting rid of the hybrid suspension the armor protection of the L-10 was increased to 24 mm compared to 14 mm of the L-30. In general the armor layout was ahead of its time, the front was well sloped and the design made extensive use of welding in its construction which was rare for the time.

 

For main armament both 37 mm and 47 mm caliber guns had been considered but ultimately a 37 mm was chosen due to its superior in rate of fire and penetration. This gun was an early version of the Bofors 37 mm which would go on to become one of the most widely used anti tank guns of the pre ww2 period. The vehicles carried 4000 rounds of 6,5 mm for the two machine guns and 122 rounds of 37 mm ammunition. The tanks were powered by an Maybach DSO 8 V12 gasoline engine delivering a respectable 200 hp at 3000 rpm, resulting in a power to weight ratio of around 17-18 hp/t. The good power to weight ratio coupled with the substantially improved suspension design gave the tanks a top speed of 40 kph on tracks. For communication the tank was equipped with a two way radio.

 

Strv fm/31 and Strv m/31 under construction

 

Service life and Legacy

After some delays the strv fm/31 and the three Strv m/31’s were delivered to the Swedish army in late 1934. By the time of their delivery the strv m/31 and fm/31 were arguably the most modern tanks in the world but unfortunately like many designs ahead of their time the L-10 and L-30 proved to have major teething issues, most of which were related to the drivetrain.

 

The transmission as well as the tracks were fragile and hard to repair, and changing the transmission required the engine and fuel tank to be removed first. During winter conditions snow would build up in the drive wheel causing the tank to lose its tracks. The extensive use of foreign components in the design meant that spare parts had to be imported.

 

Strv m/31 and Strv fm/31 at I2

Between 1935 and 1939 the tanks were stationed at the I2 Göta Livgarde tank battalion where they ended up mostly serving as training vehicles due to their reliability issues. During ww2 there were plans to convert the m/31’s to command tanks but nothing ever came of it. Ultimately the strv m/31 and fm/31 ended up being somewhat underwhelming vehicles but the experience gained from their construction would prove to be an important lesson for both the Swedish army and Landsverk. Landsverk would go on to use this experience in the making of the L-60, a modified version of which ended up replacing the Strv m/31 in 1938.

 

Note that this section is an excerpt from my full article, which can be found here: https://ritastatusreport.live/2017/11/17/swedish-tanks-revisited-strv-m-31-fm-31/

Please check it out (or contact me) for more detailed information on the tanks development.

 

Note that these tanks, at least in case of the Strv m/31 (Landsverk L-10) were concidered "medium carterpillar tanks" as per this Landsverk sales broscure from 1934

 

Data

 

Data: Strv m/31

Type: Medium tank
Weight: 11000 kg

Length: 5200 mm

Width: 2150 mm

Height: 2220 mm

Crew: Commander, Radioman/Machinegunner, Driver, Gunner

Engine: Maybach DSO 8 (200 hp at 3000 rpm)

Power to weight ratio: 18 hp/t

Top speed: 40 kph

Ammo: 122 rounds 37 mm, 3000 6,5 mm

Trench: 1,8 m

Gradient: 40 dg

Main armament: 37 mm Bofors L/45

Secondary armament: 2x 6,5 mm Ksp m/21-29

Gun elevation/depression: +25/-10 dg

Armor layout ( 24/24/20 mm

 

 

Data: Strv fm/31

Type: Medium tank

Weight: 11500 kg

Length: 5200 mm

Width: 2400 mm

Height: 2220 mm

Crew: Commander, Radioman/Rear driver, Driver, Gunner

Engine: Maybach DSO 8 (200 hp at 3000 rpm)

Power to weight ratio: 17,4 hp/t

Top speed: 40 kph (tracks), 80 kph (wheels)

Trench: 1,8 m

Gradient: 40 dg

Main armament: 37 mm Bofors L/45

Secondary armament: 6,5 mm Ksp m/21-29

Gun elevation/depression: +25/-10 dg

Armor: 12,5/12,5/12,5 mm

 

Main armament:

Spoiler

 

General data

Source:https://i.imgur.com/13TqulR.jpg

Ammunition types

Sgr m/34 (HE)
- Shell weight: 1,35 kg
- Projectile weight: 0,70 kg
- Muzzle velocity: 800 m/s
- Filler: 0,039 kg tnt

Sgr m/43 (HE)
- Shell weight: 1,36 kg
- Projectile weight: 0,71 kg
- Muzzle velocity: 800 m/s
- Filler: 0,095 kg tnt

Slpprj m/38 (AP-T)
- Shell weight: 1,39 kg
- Projectile weight: 0,74 kg
- Muzzle velocity: 785 m/s

Slpgr m/39 (APHE-T)
- Shell weight: 1,39 kg
- Projectile weight: 0,74 kg
- Muzzle velocity: 800 m/s
- Filler: 0,015 kg tnt

 

pgr m/34 (APHE)
- Shell weight: ? kg
- Projectile weight: ? kg
- Muzzle velocity: 690 m/s
- Filler: ? kg tnt

 

Penetration: Slpgr m/39

 

Penetration Slpprj m/38 & Slpgr m/39

 

 

 

 

Historical refrences:

Spoiler

 

Landsverk Provisional user manual for strv m/31 & fm/31

General data Strv fm/31

 

Speed relative to gear ratio

 

Document regarding the thickness and hardness of armor plates Ordered by KAFT from Landsverk

 

 

Drawings
 

Spoiler

 

Armor scheme Strv m/31

 

Earlier armor scheme drawing ( Strv m/31 )

 

Internal layout:

 

Scanned drawings

Spoiler

Strv fm/31 hull

Turret for strv m/31 & fm/31 (1931)

Historical gallery

Spoiler

Strv m/31

Strv fm/31

 

Source's
- Landsverk Blueprint archive (Part of Krigsarkivet in Stockholm) https://riksarkivet.se/krigsarkivet

Book - Svenskt pansar: 90 år av svensk stridsfordonsutveckling - By Rickard O. Lindström & Carl-Gustaf Svantesson http://www.ointres.se/strv_fm31_m31.htm
Book - Landsverk i Landskrona https://i.imgur.com/tJ6dJBv.jpg
SPHF's (swedish historical armor association) private archive

Edited August 30, 2018 by Sp15

[Radom 4,245]

Open for discussion

[Wolf_89 2,525]

Support this. Need my Swedish vehicles

[Milocat 4,857]

+1 for the Swedish tree.

[player62514 607]

+1

[ALIEN109 1,321]

 

https://warthunder.com/en/news/6589/current/

[Tasty95215 2,099]

 

The Strv m/31 was added as a reserve vehicle! I have to say, the 3 reverse gears is very nice. For some reason, only the coaxial 6.5mm machine gun works, even though the one on the hull is also modeled.

 

Hopefully the Strv fm/31 is added at some point, maybe as an event vehicle. I'm assuming the fm/31 is the reason this suggestion thread hasn't been closed yet.

[Cpt_Jack_Irons 464]

I'm split on this, its a nice vehicle but i don't think Gaijin would ever model its unique mechanic because of how incredibly specific it is

[Stridswombat 1,089]

On 30/05/2020 at 15:06, Cpt_Jack_Irons said:

I'm split on this, its a nice vehicle but i don't think Gaijin would ever model its unique mechanic because of how incredibly specific it is

The simple solution could be to simply implement it as 2 vehicles to add more flavour. One with wheels, one with tracks.

[eleks12 1,079]

+1

[CokeSpray 7,274]

Suggestion passed to the developers for consideration.

[leroyonly 4,311]

As Strv m/31 previously has been implemented,

 

Moved to Implemented Suggestions.