Trumpeter has released the only 1/35th scale rendition of the rare Soviet S-51 Self-Propelled Gun, mating a modified KV-1S chassis with a 203mm heavy howitzer. The kit brings together parts from their excellent KV-1 series along with all-new molding for the gun and upper deck to create a positively Russian-looking brute.

Developed by the Grabin Central Artillery Design Bureau (GAU) in 1943, the S-51 passed trials successfully in the spring of 1944, but never entered mass production. Among the more interesting problems uncovered was the tendency for the S-51 to move to a lateral displacement when firing due to the inertia caused by the high line-of-fire design. At roughly 55 tons, that must have been something to see. Also, since the elevation angle was relatively small and the recoil so strong, the nine-man crew were not able to stay on the vehicle when firing.

Opening the Box

The S-51 comes in one of Trumpeter’s sturdy boxes – (I wish I had room to keep these things after finishing the model!) The sprues are sealed in thick, heavy plastic with Styrofoam sheeting taped to one of the sprues to keep the delicate hand rails safe in shipping. A separate, closed off part of the box is used for the main hull, also separately bagged. Everything about the packaging leads you to believe that this model is going to make it to market SAFE. Since the S-51 is a derivative of the KV-1, all the parts that don’t belong, like the six fuel drums, etc., go into your spares box.

The contents of this box include:

• Main lower hull, packaged separately.
• 13 sprues in soft, light grey plastic, packaged separately.
• Two sprues of link & length track molded in tan-brown plastic
• One sprue of clear parts containing light lenses
• 2 short lengths of string for use as (1) tow cables, and (2) winch cables
• 1 small sheet of photo-etch
• 1 small sheet of decals, source unknown, containing 2 Unit decals
• 1 12-page black and white instruction booklet with 15 steps
• 1 advertisement insert containing 15 CAD images of the completed kit
• 1 five-view Painting and Marking guide with callouts for Mr. Hobby and Vallejo acrylics, and Model Master Enamels.

The Instructions

The instructions were clear and informative, and contained no errors. The only criticism I have is with the image used in Step 12, which led me astray. A slightly different angle on the view would have solved the problems I encountered, detailed below.

Things to consider before starting:

The build sequence is pretty straightforward. The lower hull and chassis first, followed by the main deck, track, fenders, and finally the gun.

The track is inaccessible once the fenders are in place, but you could leave the fenders off until the end of the build if you want to, as well as the multitude of sturdy crew railings and racks (I didn’t). The completed gun assembly drops onto the hull in the last step, so that could be built and finished separately as well.

The Build

Lower Hull and Chassis

The S-51 from the lower hull down is basically the Trumpeter KV-1 kit, an enjoyable build, resulting in a robust chunk of plastic. Like the main gun later on, the completed assembly is solid and heavy – you can’t help but think RUSSIAN.

I left off the delicate photo-etch air intake screen – you can’t see it on the completed model and it has more value to me in my spare parts box.

Track

Trumpeter provides link & length track in most of their kits, this one being no exception. I’m not a big fan – I always feel the flat parts look a little unnatural in places. Nonetheless, I chose to put the track on at this point per the instructions since I would be building the entire kit before painting anyway.

The track sections come on two separate, brown colored sprues, one sprue for each side. There are two large and obvious ejection pin marks on the inner surface of each link (see image). Some modelers will choose to cover these with weathering; while others will want to fill these before assembly. I also found a small amount of flash on some of the links.

The assembly of the track was somewhat problematic. The individual links fit together very well, but once together, the sections came up about a link and half short on the right side only. I’ve built the Trumpeter KV-1 before without any problem so the gap may be due to some assembly error on my part. Trumpeter suggests using 67 links per side, leaving 8 spare links. I used the spares to fill in the gap.

Rear Deck

What appears at first to be a daunting task at the bottom of Step 6 ends up coming together rather well. Working one step at a time, I glued the two plastic side bars (H1) to the plastic cross member (H6) and let that dry. Then, placing the assembly on my table top so that the cross member was at the bottom, I started at the top and worked downwards, first on one side and then the other. The photo-etch cross members are sturdy and provide sufficient strength for the task.

The instructions aren’t exactly clear or accurate on how all the pieces come together here, but dry-fitting everything makes things pretty obvious. I suggest you glue Parts 2xH12 and 2xH19 to the hull and let them dry completely. You can then maneuver Part M19 into place and see how the two plastic/PE assemblies slide in from each side, holding everything in place. It’s actually a pretty good design.

Tow Cables

Unfortunately, Trumpeter chose to include string cables with plastic ends in the kit, which don’t work very well. The string easily frays and the holes in the cable ends, while nicely engineered, are too small to be practical using string. I substituted the string with twisted wire from my spares box. The dimensions provided by Trumpeter for the cables are accurate, although I chose to wind my cables around, requiring more length.

203mm Howitzer and Front Hull

Steps 8-14 bring the main weapon together, and assembly was relatively easy. Trumpeter uses a novel approach to molding the end of the main tube, which assists in hiding the seam line along the top. While there are several 2-piece tubes that make up the gun assembly, the only seam lines you need to worry about are the ones on the main barrel, and between parts F10 and F11, in Step 9. All the remaining seams are covered by something else.

The only glitch that I found was a poor illustration in Step 12 that led to problems with assembly. I had to perform some ‘plastic-surgery’ to fix my problem, but had I spent more time dry fitting and examining an illustrations in Step 14, things would have gone differently.

In Step 13, my notes say that you will need six hands to bring everything together. Apparently I was able to do it with two, but I suggest that you go slow here and use slow-drying cement.

Bringing it all together

In Step 15 the entire gun assembly drops right down on the chassis leaving plenty of room to attach the handrails, if you left them off, and the two prominent front shields. Once together, the weight of the completed model is impressive - I doubt it would survive a dive off my workbench. The delicate ammunition rails in the rear (if that’s what they are) are woefully exposed, requiring finesse in handling the model during painting and finishing. Somehow, everything was completed without incident!

Painting and Finish

I decided to paint my S-51 Russian Green. I’ve looked at 4BO recipes but I thought I’d just use something off the shelf and concentrate on weathering and filters for the final color. A single-color finish will require a lot of work to break up the monotony and provide depth – luckily, this is the part of the build that I enjoy the most! I assembled the entire model before painting.

(Small Print: I thin all Model Master paints 1:1 with their own Air Brush Thinner, Gunze Mr. Surfacer products 1:1 with Gunze Mr. Color Leveling Thinner, and Vallejo's own thinner for all Vallejo paints. I thin all filters, washes and oil paints with Mona Lisa Odorless White Spirit (Paint Thinner). I use a Pasche-H Single-Action airbrush, Number #3 tip, at 20 lbs. pressure for everything.)

Primer: I started by airbrushing a primer coat of Gunze Mr. Surfacer 1200 to cover up errant glue spots and to provide a ‘bite’ to the PE parts for the subsequent layers of paint.

Pre-Shade: I followed this with a pre-shade coat of (rattle-can) Rustoleum Flat Black. I’ve found this to be an excellent alternative to my tried-and-true Tamiya NATO Black. It’s much cheaper, it dries very thin, and I can do the entire model in about 1.5 seconds. Once the pre-shade coat got a chance to de-gas in the garage, I brought it back in and touched up the spots that the Rustoleum missed with Tamiya NATO Black.

Base Coat: Next I laid down an overall base coat of Model Master Russian Armor Green. I made sure to try and miss the track and leave a little of the black undercoat coming through along the edges and in the recesses.

Post-Shade: Once dry, I followed this with a post-shading coat of Model Master Topside Green, applying it only to the exposed flat surfaces, leaving the darker color to mix with the background black in the recessed areas.

Filters: Once the paint was completely dry and still ‘reasonably’ flat (Model Master flat paints always leave a somewhat shiny surface??), I applied a single (un-thinned) filter coat of AK Interactive Track Color to the track, and two thinned coats of MIG Wash Brown Oil Paint to the rest of the vehicle. I followed this with a MIG Dark Rust filter to various spots where I thought rust might accumulate.

Gloss Coat: Next, I shot the whole vehicle with a coat of Future to prepare the surface for decals and subsequent pin washes.

Details: While the Future was drying, I painted the tow cables with a mix of Vallejo Oily Steel and Black. When I hand-paint with Vallejo paints I mix a tiny bit of Vallejo Slow Dry and water with each color until it flows smoothly off a red sable brush.

Decals: Trumpeter supplied two small decals, one for each side (of something). They are perfectly registered and ready to go – somewhere. Unfortunately, neither the instructions nor the ‘’Painting and Marking Guide’ - nor even the glossy 8.5x11 advertisement sheet - show the decal placement. I couldn’t even find the markings in the few pictures online. Consequently, I left the decals off.

Wash: I applied a pin wash of MIG Dark Wash (a.k.a/ Burnt Umber) right out of the bottle to the entire surface area, focusing on the main weapon and housing structure. Applied to a glossy surface, the wash quickly recedes into the recesses and dark corners, providing even more depth to the background paint.

Streaking: Next, while the surface was still glossy, I dabbed on some AK Interactive Streaking Grime on the vertical surfaces, including the barrel. I let that sit for two or three minutes and then started working it with a flat paint brush, using an up-and-down motion. The brush should be clean for this to work right, so whenever the brush got filled with wash, I dipped it in Mona Lisa, wiped it off on a paper towel, and continued. This process takes a while, but in the end you get a nice variation of an otherwise bland, single-color surface (see image). This technique works well to break up any solid color (American Olive Drab, German Grey, Desert Yellow, etc.) – any surface that needs a little help.

Flat Coat and Road Dust: Once I was satisfied, I shot the vehicle with Vallejo Matt Varnish to kill any remaining shiny spots. While the airbrush was set up for Vallejo, I sprayed on a very thin layer of Light Brown, working from the bottom up, and then dusted various surfaces to lighten things up a little.

Wet Pigments: I mixed MIG Russian Earth (of course!) and MIG Dark Mud pigments with a little MIG Thinner for Washes (Red Bottle) and applied the slurry to the areas behind the running gear, and to small spots here and there where mud might be kicked up. Go easy – while the pigment can be removed, it’s not easy if you put on too much. Once the slurry had dried, I used a stiff brush to remove enough pigment to tone down the brown to a point where it looked like ‘dried mud on green’, frequently dipping it in Mona Lisa and wiping it before continuing.

Dry Pigments: To break up brown pigment, I added a little MIG Black Soot here and there using a dry brush. I also applied a light dusting of MIG Dried Mud to the lower sides of the superstructure so the track and gear would not look like the only place where dust and mud had settled.

Metal Highlights: Once all the dusting and pigments and washes and filters are applied, it’s time to lay down a little bling. I feel this step is especially important when I am working with a single-color subject. I use two products, each one producing a slightly different effect. First, I apply MIG Gun Metal dry pigment, using my finger and an artist’s Color Shaper that mimics the supple surface of my finger when I am working on spots where my fingers don’t fit. The pigment goes on dull, but can be shined up depending on how much you work it into the (flat) surface. The second product is Gamblin Silver Oil paint. I scrape a little paint onto a business card to leach off some of the oil, and then use the color shaper to apply this brighter color to the tips of the track teeth. Once on, I rub the teeth with the shaper to break up the silver color just enough to show some wear through the pigments.

Oil and Fuel Stains: The last step was to apply LifeColor Tensocrom Oil, straight from the bottle, to the areas behind the wheels and around various seals here and there, drawing the color downwards like an oil stain would look. I used AK Interactive Fuel Stains to highlight the areas on the top of the vehicle where you might find spilled fuel. Like the Oil treatment, this product dries slightly glossy to help break up the otherwise flat surface.

Conclusion

Just coming off several builds that involved hundreds and hundreds of parts, building the S-51 was like a breath of fresh air. The fit is excellent, the instructions are accurate, and the engineering is sound. The issues I encountered with the track were probably self-induced since that part of the kit is duplicated here from previous releases of the KV-1, which went together without any problem.

I highly recommend this kit for all modelers, regardless of experience. It is an unusual looking vehicle, and will turn heads when displayed at shows and in your model case.

I would like to thank Trumpeter Models and Stevens International for providing this kit for review, and IPMS USA for giving me the opportunity to build it.