S-51 Soviet heavy SPG 203mm - case report

Tovarisch!!!

              Comrades... I decided to start a new project, to enjoy my last days of my vacation. The Soviet heavy S-51 SPG 230mm:

     

S-51 SPG 203mm - front view

S-51 SPG 203mm - rear view

History:

      In autumn of 1943, GAU  began the re-designing creation of self-propelled artillery systems, with large and extra-large capacity of destruction. Like ten years earlier, it was supposed to arm a platform with the 203 mm howitzer model 1931 ( I built this big howitzer... See here...), with production planned to resume at the factory "Bolshevik" in 1944. If it succeeded, WPRA would get a mobile devastating weapon. By order of the People's Commissar of Weapons Ustinov in November 1943, a competition to develop self-propelled guns was announced, which received the semi-official title of "Knight". 

   Within weeks, some preliminary drafts were presented from plant № 100 NKTP, CB Uralmash, and TsAKB. The first of them, created under the leadership of J. J. Kotin, was a self-propelled gun carriage with trailer that, in some ways, resembled the French Canon de 194 Mle GPF, but with a more powerful gun.

Canon de 194 Mle GPF

      Draft CB UZTM had two options; a 203 mm howitzer B-4 on the chassis of the KV-1S (modernized draft SAC U-19) or two 152-mm howitzers on two SU-122 chassis (The Bear).

203mm Soviet heavy howitzer B-4

Bear 152 mm x 2 SPG - artistic conception

        Before using its gun, it was supposed to connect both chassis; preparation to firing was about 30-40 minutes, versus 20 minutes with the Kotin design. It is clear that the development of plant number 100 and UZTM won't give adequate fire support due to its technological complexity. In order to build a single prototype, only TsAKB submitted a draft SAU under the symbol "S-51" (or C-51) . The chassis of the KV-1S was considered for the base of the S-51, but it was quickly discovered that the length of the support-surface was insufficient and needed adjustment: a modified version with 7 or 8 rollers. However, NKTP was reluctant to change its production because the amount of modifications required was relatively large, and the number of issued ACS was unlikely to be exceed several tens of units. To this end, it was decided to establish a howitzer on the chassis of an unaltered KV-1S anyways, which was not the best solution. The chassis did not undergo any major change, except for the engine.

      The tank turret was dismantled, and a 203-mm howitzer B-4 was mounted on the open gun-carriage. Because the weight of the 203 mm howitzer was slightly heavier than the weight of a fully-loaded turret, the full combat-load weight was almost 50 tons. Thus, it was not expected to have good mobility.

      The first prototype of the S-51 entered factory tests in February 1944, conducted under the reduced program. However, interest in high powered artillery was so great that it was still not finished was transferred to ANIOP. Here, all of the major disadvantages of the S-51 were revealed. Because of the high line-of-fire when firing, the self-propelled chassis was strongly swayed by inertia and would move to a lateral displacement. The elevation angle was relatively small, and the recoil was so strong that the crew could not hold on their seats. The severe recoil, large size and weight of its projectiles, and the extreme discomfort for the crew would require the installation of a rammer/loader. In addition, the chassis of the KV-1S proved it was clearly not a good platform on which to install guns of this caliber.

       After comparing all the data obtained in the COD, it was felt that the S-51 still be sent to production, but to no success. First of all, the issue of using KV-1S chassis was resolved in December 1942: the required amount of modifications for heavy self-propelled guns was only possible with the serious alteration of serial machines. Another important reason was the lack of the B-4 howitzer, which was not in production-scale numbers.

      In return, engineers and design bureaus TsAKB plant number 100 had developed a version of an SPG on the chassis of a heavy tank, with the installation of a 152-mm howitzer BL-2.

152 mm Soviet howitzer BL-2

      A prototype self-propelled guns, named S-59, was made in early 1944 on May-June, and underwent range tests. There is some discrepancy in the data on the type of equipment. According to factory records, S-59 received the chassis and body from the IP-85, but according to a report on the tests, the self-propelled gun had the "improved chassis of the heavy KV tank ". However, when firing a full charge, the S-59 began to have problems similar to that of the S-51, so mass production of the unit was not raised. font: http://www.aviarmor.net/tww2/tanks/ussr/s51.htm

Specs:

S-51 Soviet heavy SPG 203mm
Type	Self-propelled artillery
Place of origin	Soviet Union
Service history
In service	1944–45
Used by	Soviet Union
Wars	World War II
Production history
Designer	GAU Artkom
Designed	1943
Manufacturer	NKV TsAKB
Produced	1944
No. built	few (?)
Variants	none
Specifications
Weight	50 tonnes
Length	9.350mm
Width	3..380mm  with sandshields
Height	3.400mm
Crew	2+7
Armour	60mm hull
Main armament	203 mm howitzer B-4
Secondary armament	none
Engine	Model V-2 V12 Diesel engine 600 hp @ 1900 rpm
Power/weight	12 hp/tonne
Suspension	Torsion bar
Operational range	230/160 km (on/off road)
Speed	35/17 km/h (on/off road)

      

The kit:

      I decided to build this big girl for a long time, but just now I gathered stuff for this ...The queue of rare and strange things is huge ...So, let's go.

      To do this animal, I need a chassis (KV-IS) and a gun (B-4). As I didn' t have a pure KV-IS, I used a KV-8S (Eastern Express), who wore the same chassis. The B-4 howitzer was easier...I got a Trumpeter kit.

B-4 203mm howitzer - Trumpeter box art

KV-8S tank - Eastern Express

      Starting...The parts...

The two players...

       Man...the Eastern kit is horrible...But it's cheap and therefore, ideal for my follies ...

Poor injection and many plastic contraction...

Arrghh !!

       Notice my AEC MkII AA  waiting for  the Russian Girl (green arrow)

The chassis is growing...

Holy crap...the KV parts are awful

Return rollers

The alignment of the suspension arms is essential ...

       The wheels...

       Ufff...To rest your fingers to cut burrs, we build the Trumpeter kit, which seems to me a little better ...

Gun barrel...very good...

Minus putty to seal the seams...

B-4 almost done...

       Returning to the chassis, closing the turret hole. The parts marked with red arrows will be removed...

With the gun (dry-run). Notice the B-4 "normal" in the background...

       After the upper hull correction, let's work with the fenders...

Raising the fenders...

Putting internal reinforcements ...

Fenders like crew's platform...

Building the frontal racks...

 Primary howitzer's mounting (blue arrows)  and
parts of the upper hull removed (red arrows)...

Starting the secondary howitzer's mounting

Secondary howitzer's mounting done and glued in place

Making the reinforcements with Plastruct

Testing...

...testing...

...and testing...

Drawing the rear structural reinforcement...

Close-up..

Under construction...

And the rear structure in place...

Testing the movements...

       Now, it's time to make the antiskid flooring for the crew ...

Cutting plasticard...

Notice the details...

Rear brackets...

...for the rear steps

Building the rear steps with copper wire and electronic weld.

Making the points in the rear steps with plasticard and superglue...

       Build the towbar support of rear with scraps of photo-etched...

Welding job !!!

And the metals in place !!!

The rear steps moving...

Rear view...

       And now, the frontal gun shields

The plastic cutted...

...and the shields built!!!

tow cables...

Tow cables in position, in the rear deck

       I started the building of the mobile supports of the gun shields. Metalworking and welding ...

The supports with tape...

Welding...

       Meanwhile, I built the shields in the hull. The shields may be move to front by hinges ( yellow arrows) Notice the reinforcements in the shield (red arrows).

       Notice the internal part of the shields: antiskid flooring from my spare parts box

As the shields become platforms for the crew,
the antiskid flooring is a necessity ...Notice the
stop device (red arrow)

Installing the supports of the gun shields...

In place...

Notice the details in the real beast...

The shields turning platforms...

The supports in the tracks...

Compare with the real.....

It's a huge Girl !!!

Making the external handrails: copper wire and weld...

Done...

Making the internal handrails: copper wire and weld, again...

And installed in the vehicle ...

       And the Girl is ready for painting...

Side by side with another B-4

Eyes up !!!

Small advances, in this weekend ...I received these beautiful things, by Mail ...

Ammo for my girl...

      And talking about ammo, I built ​​in scratch the rack of cartridges on the right fender of the vehicle. See the pics below:

The ammo rack...

...in position!!

       And also did some internal details of the tank ...Driver position and lateral racks...

Tovarich...Start your engine...

       Final detail: a jack for maintenance of suspension ...in scratch, of course...

The tool in the rear deck...

       After primer, Russian Green (Vallejo):

       After Future, decals:

     I decided to make a field adaptation in this vehicle. Some kind of support for the ammunition that would be used immediately. First, a wooden base ....

A wodden plank...

two wooden slats strung on the banister

    And the ammo supported in this structure, tied with a rope ...

The ammo ready for immediate use...

Comrades...the huge girl was ready: Iused Mig pigments and a a branch of Pomegranate (Punica granatum) as a log. The Pomegranate is perfect, in scale, for  this...

           By Motherland !!!

S-51 Soviet heavy SPG 203mm - front view

       Upon ammo rack, a bedroll from  Value Gear. Excellent stuff...

S-51 Soviet heavy SPG 203mm -  right side

S-51 Soviet heavy SPG 203mm -  left side

S-51 Soviet heavy SPG 203mm -  firing position

S-51 Soviet heavy SPG 203mm -  the log and the howitzer

S-51 Soviet heavy SPG 203mm -  Massive girl...

      And who finally returned from well deserved holiday was Kojak, with a new uniform and excited about your new toy ...Wellcome back, Tovarisch !!!

S-51 Soviet heavy SPG 203mm - rear view

The Girl really is so big !!!

Go to the West !!!

Notice the howitzer's shield as platform...

S-51 Soviet heavy SPG 203mm

     Thanks for following, Gents !!!