Tuesday, 29 September 2015

Project EMIL: The Swedish “heavy tank” project

Author: sp15

Before we start, yes i know this is effectively the third time I'm revisiting this topic. But with this article I wanted to give you the full story behind the development of the "kranvagn". I'm not going to list a lot of technical specs here so if you want those take a look at my earlier articles on the subject:

Swedish Tanks – Part XII: EMIL 1951
Swedish Tanks – Part XIII: EMIL 1952-1958

During the early 1950s the Swedish army was facing the obsolescence of its tank force most of which was still composed of 37mm armed light tanks. And with the cold war heating up in Korea the Swedish military issued a demand for acquisition of a new medium tank. This would lead to the Start of Project EMIL, a project that would ultimately prove too ambitious for its day.

There had been attempts to acquire a new tank for the Swedish army stretching back to 1944 when the army had called for two types of heavier tanks to be developed. The first of which was an up-gunned Strv m/42 with a new turret and a new 30 ton tank design with heavier armor and armament called the Pricken. But with the end of ww2 the development of the 30 ton design was discontinued and only a prototype of the modified Strv m/42 was built and tested unsuccessfully in 1946. Instead Sweden went looking abroad for its new tank. In 1946-47 attempts were made to acquire the Sherman firefly from the British army however due to complications mostly concerning the availability of spare parts meant that the deal was called off and only one Firefly and a number of other Sherman variants were acquired for testing purposes.

But Swedish tank development had not stopped. Landsverk who had designed and built tanks during WW2 was working on a number of export projects at the time. In addition they were also working on a 30 ton tank destroyer/medium tank for the Swedish army. However in 1947 when Landsverk was gearing up to produce the prototype the army command suddenly decided to discontinue the development of all tank designs over 20 tons. Instead in 1949 development was shifted to one of Landsverk’s 20 ton light tank designs. Ironically enough the project was terminated when the army command came to the conclusion that a tank with a weight limit of just 20-25 would be of little value against contemporary medium tanks.

Landsverk's Lansen light tank design

In 1950 after a series of failed attempts to purchase Centurion or the M46 Patton the army decided that it would start development of a Swedish replacement for the Strv m/42 under the name Project EMIL, and trial the AMX 13 light tank. In 1951 the first draft was drawn up for the new tank.

The concept
The EMIL was essentially meant to be a Swedish proto-MBT, it was a design that was to be capable to take on anything it might encounter on the battlefield and still have the mobility required in Swedish terrain. Its firepower would remove the need for dedicated tank destroyers and its armor would help protect it even against heavy tanks. And all this while still being within the weight limit set by the Swedish military command. The chassis would also be used as a basis for a 15cm SPG and a 57mm self propelled anti aircraft gun that was in development at the same time.

EMIL 1951 proposal drawing

The 1951 proposal had been heavily influenced by the AMX 13 and had borrowed the idea of the oscillating turret and cassette autoloader. The turret front was reworked from the French design to allow better protection by extending the lower part connected to the turret ring to create a one big frontal piece instead of the oscillating upper turret part and fixed lower part on the AMX 13 design.

The idea of an autoloading high caliber tank gun had been researched by the Swedish army since before 1950. The thought was that a large caliber gun shooting HEAT ammunition would be able to reach the kind of penetration numbers the army was looking for. And the autoloader would allow rapid re-engaging of an enemy target if the first shot missed. But at the time the idea had been strictly theoretical due to the weight constraints. However with the oscillating turret such a gun could be carried by a much lighter vehicle than a more conventional design.

One of the main requirements of the project was that the tank had to be constructed within the country. This stemmed from experiences from ww2 where Sweden had been cut off from acquiring foreign tanks. That meant that practically all tanks used by Sweden during the war had to be developed and built from scratch, this was a mistake Sweden did not want to repeat.

The development of the vehicle was divided up between three companies. Landsverk who handled development of the hull, implementation of major components, work on the mock up and the hull assembly. Bofors was in charge of the development of the turret, gun, and autoloader mechanism. And SFA was in charge of acquisition and development of the engine. The whole project was estimated to take about 3-5 years from start to finish with the major components worked out and put on paper within a year. But in 1952 there was still questions to be resolved like the engine choice, weight limit and armor thickness. To finalize the requirements for the tank a series of discussions and investigations were held in 1952.

Originally the engine considered for the EMIL project had been a 550hp engine from SFA but in 1952 it was decided that the tank would use a license built American tank engine. Several engines were considered in the range from 500 to 810hp. This lead to the EMIL being split into three different versions with different engines and weight limits. However the different versions all shared the same basic layout. Compared to 1951 vehicle there were several changes which included a reworked suspension, wider tracks, redesigned frontal armor inspired by the IS 3 and a change from welded to a cast design for the rear of the turret.

EMIL E3 Mockup from 1952

The lightest model referred to as EMIL alternative 1 (or E1) of was based on the original 1951 requirements. It was estimated to weigh about 32t depending on the armor-thickness and engine chosen. It would also be armed with the same 12cm gun as the 1951 proposal. It was considered in case only the low powered engines could be acquired. The EMIL alternative 2 was the mid-range model, it was bigger and heavier than the E1 with a weight between 34 and 39 ton’s depending on the armor and engine. It was to be equipped with either a 540hp or 665hp engine which would give it a power to weight ratio of 17-20hp/t. Initially this was the preferred model of the tank as it had more upgrade potential than the E1 while still being viable with a Swedish engine. However with the confirmation of the availability of the high power engines the E2 was no longer needed and as with the E1 development was likely discontinued by the end of 1952. Alternative 3 was the heaviest model with a weight between 38 and 42 tons. This version was seen as unrealistic as no Swedish engine was available at the time, but it became the preferred model once the American engines became available. The E3 had the same armament as the E2 model (150mm smoothbore) but was able to have heavier frontal and side armor while still maintaining a high power to weight ratio. In late 1952 the E3 model was chosen for further development over the E1 and E2 and became the basis for all future versions of the EMIL project vehicles.

In 1953 after having pulled out of negotiations about purchasing the AMX 13 at the last minute after the personal intervention of the commander in chief Sweden purchased the Centurion Mk.3 tank. With the immediate need for a new Swedish medium filled the fate of the Emil project was uncertain. Ultimately it was decided that it should be continued although with decreased priority since the performance of the Centurion was seen as inferior and there was still a need for a better tank in the future.

Shortly after in 1954 Bofors announced they were having serious problems with development of the turret. In particular with the gyro stabilization and the ammunition for the main gun. Earlier on in the project there had been a decision to split the development of the gun and ammunition. Bofors would handle the development of the gun and army ordinance administration would handle the development of the ammunition. As you might imagine this caused all sorts of miscommunications. In turn this meant the development of the HEAT round would not be possible within the promised timeframe and Bofors suggested using APDS rounds or HESH rounds instead. Elsewhere things were going better. SFA had begun testing their own engine for the EMIL project alongside the American engine. This engine exceeded the output of the American one and after some extensive testing it was decided to use the Swedish engine. A series of other changes were also made in 1954 the biggest of which were changes to the turret to improve the gun elevation from -12/+8 degrees to -12/+12 degrees. This would allow better stabilization for the gun. This also increased the turret weight by 3 tons even with a slight armor reduction to for the turret sides.

Krv hull drawing

At the end of 1954 the Emil project was entering a critical phase, with most of the drawing work done and the engine chosen preparations were made for the construction of the first prototype. Originally there were plans to build two prototype hulls to be ready by May-June 1956 with a third chassis following in 1957 for a 15cm SPG project. Instead only one prototype tank chassis was actually finished with the other being reworked for the SPG role. To confuse any potential spy the prototype hull referred to as “Kranvagn” or its shortened version “Krv”. The hulls were used for testing off-road performance and reliability until Bofors could deliver the turrets which was supposed to happen in 1957. In the end Bofors proved unable to develop the main gun. So in 1958 as a last effort to salvage the project it was suggested that a British or French alternative should be considered, later there were even plans to mount the Centurion Mk.10 turret on the Krv chassis as an alternative to the S-tank, but nothing came of it. This and along with the purchase of the Centurion Mk.10 came to mark the final nail in the coffin for Project EMIL.

The prototype "Kranvagn" during winter trials 1957

While project EMIL itself ended in failure it did serve as a valuable exercise for the Swedish army. The research that had been done as part of project EMIL became used as a basis for the early development of the S-tank. The “Kranvagn” chassis became one of the earliest proof of concept vehicles for the S-tank and was used to test the hydraulically adjustable suspension. And the SPG version later resulted in the Bkan 1, which was one of the most impressive artillery vehicles for its time. The cancellation of project EMIL would also mark the last time Sweden would consider the idea of a tank heavier than 40 tons until the 1980s.

Today the hull is located in the storage facilities of the Arsenalen museeum. It was recently measured by WG's own historian Yuri Pasholok during a visit earlier this month. Here is a couple of photographs taken of it by Renhanxue (who like me is working on the Swedish wot branch) during the visit.

Next time we will be taking a look at the UDES 03. A project for what was essentially a light tank version of the S-tank.

RG: Hope you enjoyed! Feel free to leave any questions. :)

1 comment: