Kranvagn: Swedish heavy tank development

Author: Sp15

Silentstalker:

Hello everyone,

today, I have a guest article from you from player sp15 (US forums), dedicated to Swedish heavy tank development. Enjoy!

Sp15:

Recently about 90 pages of information on the Krv project was found by EU and NA player Renhaxue. I’ve myself been working closely with him and I thought we might as well share the information we have now that we have the archived documents.

So without further ado let’s start. After World War Two, Sweden’s tank force had quickly become outdated, the most advanced tank in service was the Strv m/42 which was the equivalent of an early model Sherman, and it was clear that something better was needed. So in 1949, Sweden did set requirements for a new heavy tank. It seems this project was a response to the development of western heavy tanks by the Americans and British and like their heavy tank projects, the main goal was to counter the threat of the Soviet IS-3.

AKV “1949″ SPG

emil

We don’t know exactly how this first 1949 version looked like, but there is a schematic for a SPG based on the Krv, or rather Project EMIL from 1949 (since Krv Aka Kranvagn (“Crane vehicle”) was the cover name for the prototype hull).

Project EMIL, 1951

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Then there is a gap in the knowledge of the project until 1951. We have full documentation on the project including schematics from that time. An interesting thing to note is that the hull appears to be largely unchanged from the 1949 SPG.

At this point the projected vehicle was a frontally heavily armoured but still mobile, weighing 28 tonnes, at this point the only armament was a 12cm rifled gun meant to fire heat ammo with a stabilized warhead, although there were plans for a subcaliber shell.
Here are the full stats and the schematics for the 1951 version:

Combat weight: 28 ton
Length total: 7,4m
Length excluding gun: 5,8m
Width: 2,6m
Height excluding aa-machine gun: 2,35m
Track width: 0,55m
Ground clearance: 0,4m
Crew: 3

Armament: 12cm Autocannon, L/40

Engine:SFA 8 cyl
Engine output: 550hp
Power to weight ratio 19,5 hp/t

Armour:
Turret: front 150mm at 45°
Sides, front 125mm at 80°
Sides, rear 30mm at 90°
Roof, 18mm at 0°
Hull: front, UFP 70mm at 22°
LFP 125mm at 38°
Sides 20mm at 90°
Roof, front, 30mm at 0°, rear 18mm at 0°
Rear 30mm at 90°
Floor; front 40mm at 0°, rear 15mm at 0°

The next info that we have on the project comes from a 1952 report, by this time it is determined the project should move on and the 15cm smoothbore gun has been chosen as the main alternative for the project with the ability to mount a rifled 10,5cm gun in the same turret as a backup.

There is a lot of talk about possible engines for the project all of which are air cooled American ones ranging from 500 to 810hp and based on which of these engines and which weight limits were to be used, 3 options for the tank are presented. For these, different armour values are discussed for frontal armor (hull lower: 120mm ,hull upper: 75mm, turret front: 140mm) or (hull lower: 145mm, hull upper: 95mm, turret front: 170mm) and side armour (turret/hull) (40/20),(60/30) or (80/40), although the heaviest combination of armour is only deemed viable on alternative 3.

Alt EMIL 1

Armed with a 12cm gun and using the 500hp engine, this tank can be reduced in size from the preferred alt 2.
This option corresponds with the original draft, it would weigh 29.5-33 tonnes with little to no upgrade potential for the armour.

33,3 tonnes
Length: 6,40m
Width: 2,84m
Height: 2,46m
Crew: 3
hp/t: 15,1

Max speed: 48kph
Ground pressure: 1,10kg/cm^2
ground clearance: 0.4m
Track width: 0,6m
Road wheels: 6

engine:AOS-195 (500hp)

armament: 12cm L/40
fire rate: 30rpm
Ammo capacity: 28
magazine load: 14
elevation/depression: +8/-12

Armour turret:(140/40/20)
Armour hull: (120/20/18)

Alt EMIL 2

Armed with a 15cm gun and with 10.5cm as an alternative, using a 540hp or a 665hp engine if possible. Side and frontal armour is upgradeable with the more powerful engine, this is the most realistic and preferred version with a weight of max 38 tonnes.

38 tonnes
Length: 6,40m
Width: 3,00m
Height: 2,56m
Crew: 3
hp/t: 18,1

Max speed: 56kph
Ground pressure: 1,20kg/cm^2
ground clearance: 0.4m
Track width: 0,62m
Road wheels: 6 (there were drafts with 8)

engine: AV-1195: (540hp), AVS-1195 (665-668hp)

armament: 15cm L/40, 10.5cm L/67
fire rate: 30rpm
Ammo capacity: 24
magazine load:12
elevation/depression: +8/-12

Armour (turret):(170/60/30)
Armour (hull): (145/30/18)

Alt EMIL 3

Armament same as alt 2, only possible with the 810hp engine, therefore it’s considered somewhat unrealistic. This alternative, while bigger than the first two, has potential to mount the heaviest armour and still reach the weight of only 42 tonnes with a power to weight ratio of around 19hp/t

42 tonnes
Length: 6,75m
Width: 3,05m
Height: 2,66m
Crew: 3
hp/t: 19,5

Max speed: 60kph
Ground pressure: 1,20kg/cm^2
ground clearance: 0.4m
Track width: 0,62m
Road wheels: 6 (there were drafts with 8)

engine: AV-1790 (810hp)

armament: 15cm L/40, 10.5cm L/67

fire rate: 30rpm
Ammo capacity: 24
magazine load:12
elevation/depression: +8/-12

Armour (turret):(170/80/30)
Armour (hull): (145/40/18)

Im sad to say we don’t actually have the schematics for these proposals (other than the 1951 version) that should have been in the documents, but the Swedish archive system isn’t very good, at least when it comes to these kinds of things…

Anyhow, the next info we have is from 1955 where there is some concern over the development of the ammunition for the 15cm gun, the 810hp engine has also been procured for study and it provides the base for a Swedish developed engine.
The Swedish engine is able to produce a maximum of 723hp and it is what would have been mounted on the Krv. A prototype chassis is also under construction at Landsverk. Meanwhile, Bofors is asked to reduce the turret armour to (side 70mm)(rear 30mm)(roof 22mm)(bottom 18mm), if necessary for stabilization.

Requirements are also made to increase the possible elevation to +10 degrees, which increases the turret weight by 2 tonnes to 17 tonnes. This and other changes makes the tank reach the final weight of 45 tonnes.

Mock up of the 45 tonne Krv

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The “Kranvagn” hull with a dummy turret

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Next information we have is from 1958, by this point it is clear that the development of the ammunition for the 15cm gun is a complete failure and that the 10,5cm gun isn’t powerful enough. There is serious doubt whether the project should continue and French and English options for armament is discussed, allegedly there was also a proposal to mount a 15,5cm gun on the tank, but this too came to nothing. Shortly after, this the project got cancelled, but it would serve as a valuable basis for future Swedish armored vehicles, such as the S-tank and Bkan 1.

It seems clear that the built hull was part of the most ambitious plan EMIL 3, which would have been impenetrable for the IS-3 from the frontal sector with 220-240mm of effective armour. I’d like you to take this with a pinch of salt, but here are my estimated stats for the final Krv model based on what we know:

Krv 1958

45 tonnes
Length: 6,75m
Width: 3,05m
Height: 2,66m
Crew: 3
hp/t: 16

Max speed: 60kph
Ground pressure: 1,20kg/cm^2
ground clearance: 0.4m
Track width: 0,62m
Road wheels: 6

engine: SFA F12 (723hp)

armament: 15cm L/40, 10.5cm L/67 (British or French alternative?)

fire rate: 30rpm
Ammo capacity: 24
magazine load:12
elevation/depression: +10/-12

Armour (turret):(170/70/30)
Armour (hull): (145/40/18)

Today, that one prototype Krv hull still exists in the Swedish Arsenalen Museum, but it is not on display. Note that this hull has had 4 of its road wheels removed during suspension tests during the development of the S-tank.

Krv prototype hull today

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I’m not going to talk about how the tank could or should be balanced in the game, but I will say that from what we currently known the Krv project can cover tier 8-10 and no known model is viable for tier 7. This means that it would have to connect to another line or that it would be preceded by a Swedish medium line, in any case I hope you enjoyed reading this and i hope it explained the EMIL project to you.

Also please do visit Renhaxue´s blog at http://tanks.mod16.org/ if you want to read the latest wot relevant news from the Swedish war archive

Sources:
http://www.ointres.s…storia_bkan.pdf
http://www.ointres.se/strv_103.htm
http://tanks.mod16.o…paag-and-tanks/
http://tanks.mod16.o…emil-a-summary/
http://tanks.mod16.o…rrent-projects/
http://tanks.mod16.o…jects-may-1954/
http://tanks.mod16.o…s-project-6400/
http://imgur.com/a/7r9lg/all

46 thoughts on “Kranvagn: Swedish heavy tank development

  1. It really had 30 RPM RoF?
    Even taking the small gun(10.5cm) it’s huge…and judging the fact it carried only 24 rounds means it would fire all of them in less than a minute…

    Also, Frank, a tiny typo:
    “… I have a guest article from you from player…”
    Shouldn’t the first “from” actually be a “for”?
    :P

    • well the mechanical fire rate of the gun was 30 rounds per minute, the maximum ammount of rounds that could be loaded into the magazine at one time was 14.

  2. “Not SerB” removed. If you didn’t spam your stuff under articles and bothered to contact me directly, I’d be willing to listen, but this way, you can sod off.

  3. Lol, Silent, I think that the comment section is having some weird bug :P It didnt delete all the replies to the guy’s comment, but just his comment :P Now it looks weird xD

  4. Great post SS, i like the design of ”45 tonne Krv” (which looks like 50b :D)
    Post more of this stuff !
    OFF TOPIC:
    What the fuck is wrong with WG EU ?!
    Surprise calendar 12.12 : |Matilda IV + 50% off| ….
    so i press premium shop to see if it fits thouse few € left on my old pay safe card
    what i see is: 0.29€ (crossed out) … and new price 4.88€ (why is the new price like 1682.7% higher ?!)
    PICTURE SAYIN: MATILDA IV + slot 41% off (wasnt it 50% ?)

    youtube video of my feelings: http://www.youtube.com/watch?v=8TBQywGmMjQ

  5. More autolelding tanks…more tanks that can dish out 1K+ damage in a few seconds whilst leleleleleing to victory. Yeah…no. This game doesn’t need anymore autoloaders if they are balanced like the current ones are.

    • autoloaders are the cancer of this game…they never should be introduced in the first place….fuck them frenchies who started the thing

      • Agree to this. A few autoloaders are fine, maybe for the scouts, and that’s it. When they put them on things that are even halfway survivable (heavy and medium tanks) , then it just breaks the game.

  6. “12cm rifled gun meant to fire heat ammo with a stabilized warhead, although there were plans for a subcaliber shell.”

    You’re talking about 12cm armed HEAT standard ammo -12° gun depression mobile heavy?

    TAKE MY MONIEZ!

    • HEAT ammo can still bounce. And knowing WG the stock ammo will be made premium ammo. And some POC will be made the new “stock” ammo. Just look at the Char B1.

  7. With those amounts of ground pressure and only 5-6 roadwheels (resulting in large Mean Maximum Pressure) the mobility of those tanks would be abysmal, especially in snow and muddy terrain. Weight and HP/ton are only one side of the equation when it comes to AFV mobility.

    • there are detailed calculations on the speccific ground pressure of the tanks, and there were even drafts with 8 roadwheels, and there was several options for track width aswell so ground pressure shouldnt be a big problem, depending on which verison you put in the game

  8. Considering the size of the tank and the armor they wanted + the size of the gun and expected speeds their weight seems perhaps off?

    the Americans when building the T1/M6 heavy thought the thing would weigh around 40-45 short tons, end up weighing closer to 60+

  9. I really hope they flesh out the European trees.

    Diversity is the best part of WoT. Not every tank has the exact same weakspots. It’s always interesting to come up against a rare tank or a less used one. You have to learn the weakspots and how to take them down.

    Sweden developed a unique and viable tanks that really should be in the game. WoT pays homage to the designers of these tanks.