Tamiya M4 Sherman Project

First, a Bit of Tamiya Tank History

Many Tamiya fans believe that the first Tamiya RC was the 58001 Porsche 934 Turbo RSR. While that was indeed the first RC car, the first Tamiya RC of all was the 56001 M4 Sherman tank model two years earlier in 1974 (it was called RT-1601 at the time). The model was designed by Dr. Fumito Taki who had recently transferred from the accounting department. The original idea was to use the German Maus tank as the subject, but they soon learned that due to the tank geometry it wouldn't turn well and the tracks would easily get clogged with debris. They needed something short and driven by the front sprockets which gripped the tracks at the outer edge. This made the M4 Sherman the only viable option. The other advantage of the Sherman was that some uncommon versions used a 105mm howitzer instead of the standard 75mm cannon, and this short barrel would be less likely to hit obstacles, making it more suitable for a running model. So Dr. Taki headed off to the garrison at Higashifuji to measure the real thing for a scale model. After making a few mockups from wood and clay, he proceeded with the gearbox.

In these earliest days of RC, proportional controllers scarcely even existed. For that reason, the original Sherman tank was basically a static model with a gearbox that could be built using 0-2 channels (cutaway shown at upper left). The gearbox had two sides like a skid steer which could be connected independently to two 360 sized motors or connected in parallel sharing a single spur gear. Each gearbox side had a clutch at the forward end which was spring loaded to grip the input gear. However, if the front of the clutch housing were pushed forward it would gradually release the input gear and connect to ground instead. In the simplest setup, the motors were just connected in parallel with no RC at all. The model could simply be turned on and off and would drive forward when on. Because the left and right sides were hard coupled together, it would drive straight. The one channel version was intended to use the old controllers with one toggle button. In this configuration the motors were connected to each side separately. It would drive straight forward until the button was pushed which would simply disengage the left hand motor causing a turn. Stopping, turning right, and going backward were not possible. Even the most deluxe configuration was still very electronically simple (but mechanically complex). A proportional servo was used for steering. It was connected to a wide crank which could contact either clutch, so by rotating the servo either side was gradually disengaged and then grounded. This allowed proportional turns all the way to stopping one track. Pivot turning was not possible. Incidentally, many early tanks used a similar clutch and brake turning system. The prototype gearbox was made by Dr. Taki himself on a lathe. It worked perfectly and even allowed him to attempt a version with a water cooled engine. There were no speed controllers yet, not even mechanical, so there was no proportional throttle. Instead, another servo just contacted either a forward or reverse switch. This means the model could be stopped, full forward, or full reverse. This was the full extent of the controllability. No remote control of the turret or barrel was possible. In terms of scale realism, the real 105mm didn't have powered turret traverse or elevation, so the lack of these features on the model is actually correct.

Tamiya made three more RC tanks over the next few years (Leopard A4, Flakpanzer Gepard, and King Tiger) which each progressed a bit in terms of technology. The Leopard used the same gearbox but switched to a single 540 motor. The Gepard used the same thing but added a proportional mechanical speed controller and an optional 3rd channel with it's own battery that rotated the turret, elevated the guns, and rotated the search radar all at the same time. The Tiger used a modified version of the same gearbox, a rotating turret, and a strobing light in the barrel. This 4-channel version was the most deluxe tank of that original generation. Then things went quiet for 18 years!

In 1998 Tamiya finally came out with a "new" tank, and for this new generation the M4 Sherman was the first choice again. Outwardly this new 56005 Sherman was indistinguishable from the original, using all the same plastic body parts and suspension. Inside, however, everything was different. A pair of new gearboxes using 380 motors was introduced. These gearboxes lasted a long time. They were used in new tank models up until 2016 and are all still sold today. The real revolution though was the DMD (Dual Motor Differential), a twin motor electronic speed control box. Using this controller, power to each gearbox could be modulated separately. The transmitter signals were mixed inside the DMD allowing the driver to use standard throttle and steering controls instead of skid steer. It was still a 2-channel model though with no turret control.

There were only two models in this second generation before the next leap forward. The next thing Dr. Taki wanted to do was add sound. He originally intended to just add sound to the existing King Tiger to improve sales, but Tamiya's boss suggested doing something totally new. The Tiger I in 2000 added a Multi-function Unit (MF-01) to the DMD. Not only did this add two more proportional channels for turret rotation and gun elevation, it also added sound effects, lighting, gun recoil, and muzzle flash. Every 1/16 Tamiya tank since then has used a variation of this system. The sounds were recorded from a real Tiger tank by an employee on a trip to the toy fair in Nuremberg who was asked to take a side trip to the Saumur Museum in France to record the sounds. Amazingly, they were willing to start it up for him and let him record the sounds! It was only a year later (2001) when the Sherman came back for its third and ultimate configuration. This is like the Special Editions of the Star Wars movies. It is the version that Dr. Taki always wanted to make but didn't have the technology at the time. The 56014 Sherman used the same body and gearboxes as the 2nd generation, but added all the new sound and turret functions. This is the version I have.


The Tamiya M4 Sherman 105mm Howitzer

This particular version of the M4 Sherman selected is pretty unusual. The M4 was made in at least 19 different versions over a period of just two years. The Tamiya version is recognizable by the combination of the 105mm howitzer, the HVSS (Horizontal Volute Suspension System), and the radial engine. 841 out of a total of almost 50,000 were made in this configuration at the Detroit Tank Arsenal.

So what does "Horizontal Volute" mean? This refers to the springs used in the suspension. Most suspension uses coil springs but these have some big disadvantages for tanks. Because of the weight a very large wire diameter is needed which means the solid height of the spring is very tall and therefore the suspension has hardly any travel. A volute spring is made in a tapered spiral out of wound rectangular bar stock. Because it is tapered, it nests when compressed and has much more travel. Most M4s were made with the volute springs arranged vertically, but a few later models used horizontal springs connected to pivoting bogies mounted in pairs. The system used in the model is made to represent HVSS although it actually uses coil springs hidden inside cans to simulate volute springs.

Early versions of the M4 Sherman used a 75mm cannon which was later upgraded to a higher velocity 76mm version. Even less common were the versions armed with a 105mm howitzer which was really intended for use against infantry rather than other tanks. The model uses the 105mm version for the reliability of the short barrel in an RC application.

There were also a wide range of engines used in the M4 Sherman. The model represents a version using a 15.98 liter 9-cylinder radial engine from Wright Aeronautical. The distinctive sound of this engine was recorded for the model. The sound is contained in the MF-02 unit which is unique to this model. The DMD T-05 is also unique to this model.

There were also variations of the Sherman in different combinations of cast and welded hulls. The square sides of the model represent the welded hull version.

The kit was available in two versions, one with a radio and one without. By the time I was looking, I could only find one so I ended up with a 27MHz AM radio I will never use. It was still worth it. This tank is awesome. It turned out to be everything I hoped. I don't know how they can make it better, so I'm betting against a fourth version. Everything can be controlled remotely using only a 4 channel transmitter. Remote functions include throttle, steering, turret rotation, gun elevation, main gun firing, machine gun firing, and turning lights on and off. Most functions are accompanied by sounds which are automatic. Speed and power is good despite the small motors.



Like almost all of the Tamiya tanks, the Sherman comes with deluxe packaging. The outer panel is actually a pretty plain olive drab, perhaps to discourage theft. Once you open up that flap though, you see a huge piece of art work, a full list of features, and a bunch of windows highlighting some of the parts.

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The picture on the left shows the main display highlighting the tracks, the electronics, the speaker, and the gearboxes in clear windows. There are also photos and descriptions of most of the primary technical features of the model. The picture on the right shows the inside with the box top removed. Here you can also see the metal sprockets and suspension arms as well as the main hull piece.

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To my surprise, there was a full 27 MHz AM radio system and 7.2V Ni-Cd battery hiding under the metal parts blister pack. I didn't intend to buy the version with a radio, but that's what I could find when I was looking. Note that this is only a 2 channel radio, but all functions are actually controllable with only 2 channels, albeit with a more clunky interface than when using 4 channels. I will not be using this radio for obvious reasons and will probably sell it to a vintage collector. On the right you can see the large speaker box. This is actually quite heavy implying that the speaker has a decent sized magnet on it which will be a good thing for projecting the engine sounds.

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Here are the electronic units which are the heart of the model. The DMD (Dual Motor Differential) is essentially a 4-channel ESC (Electronic Speed Controller). The 2 main channels are 20 Amps each and control the dual 380 drive motors. The DMD mixes the driver's throttle and steering commands to control the independent track motors. There are essentially 3 modes. At very low throttle, a steering input causes the motors to run in opposite directions resulting in a pivot turn. At moderate to full throttle, moderate steering input is mixed allowing gradual turns at variable radii. At full steering input one side is locked allowing a sharp turn. High speed pivot turns are therefore not possible which is probably a good thing. The remaining 2 channels are 2.5 Amps and drive the turret motor and elevation motor. The DMD T-01 was released in 1998, but in 2001 the T-05 was already in use. The T-01 only supported 2 channels, but the T-03 already supported 4. There is no other obvious difference between them. The MF-02 (Multi Function Unit) controls the engine sounds, lights, and has a high voltage output for the muzzle flash. The MF-02 is unique to this model because it uses the radial engine sounds.

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The 56005 Sherman was the first to use these gearboxes which were carried forward for the 56013 release. These come assembled and ready to use, but that did not stop me from tearing them down to figure out how they work. Note that the left and right gear trains are the same, but the motor placement is different. This allows them to overlap for minimum space consumption in the model. That black lever you see on top of the gearbox is used to engage an optional gear ratio, but that optional ratio is locked out by spacers in this model.

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The path through the gearbox is convoluted to say the least. The photo at the left is my attempt at a torque diagram showing the path of torque through the gearbox. The table at right is the result of my teardown of the entire gearbox and painstaking counting of all the teeth. We start with a tiny 10 tooth pinion and then pass through 8 gear stages. Note that the final stage is actually a speed increase which is a very strange thing to do since it cancels out some of the previous reduction and adds additional inefficiency. It seems to have been done purely for spatial purposes. That penultimate gear diameter was needed to reach the output shaft. The result is effectively a 60:1 gearbox. In the event the optional gear ratio could be used, the 4th gear set ratio would change to 2.06:1 (35:17 instead of 32:20) and the final drive would change to approximately 77:1.

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I did the same exercise on the much simpler turret rotation gearbox. We begin with a worm drive from the motor which results in a huge gear reduction as well as preventing backdriving. The final ratio is almost 3000:1. I did a little quick math on this assuming a motor speed of 18,000 rpm which results in 360 degree turret rotation in about 9 seconds. This seems like a very scale accurate speed. A close look at the last gear stage at the top left of the left image reveals a ratcheting clutch which prevents breaking anything if the turret rotation is blocked.

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Finally, here is the same analysis for the elevation gearbox which is very similar using the same motor and worm gear. The final ratio is about 1100:1. Note that this output only ever moves a couple of degrees to lift and depress the barrel. The total elevation above level available on the model is not very much and is probably based on a tank with a scale 75mm gun. The 105mm howitzer was capable of elevating much higher (35 deg) which the model does not replicate.

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At this point I had to hook up the entire electronics package and try everything out. The sound of the startup of that radial engine is really impressive. From what I can tell, the main headlights and tail lights are actually incandescent bulbs, but the machine gun uses an LED. 2001 was early for LEDs. The muzzle flash is some sort of high voltage neon. It is very bright and illuminates very briefly. You can hear the high pitched whine of it recharging after firing.

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This is a relatively small number of plastic parts compared to the Leopard 2A6 which I had built previously, but still vastly more than any regular RC vehicle. This is really a plastic model kit sitting on top of an RC platform. Almost all of these parts are common to the original model from 1974.

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And here I've unpacked all of the hardware and am ready to start building. Let's go!

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Building the Suspension

The build starts with the main hull structure which is a piece of bent, formed, drilled, and tapped aluminum sheet metal (1mm). The picture on the right shows the main road wheel support brackets installed. These appear to be aluminum castings. The idler bracket is also metal, but the idler wheels are plastic. These parts appear to be common to the original 58001 Sherman, but unlike that model they come pre-assembled here. I assume that is to avoid getting glue into the bearings when installing the metal hub cap which would have been a real danger building the original.

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Here is some very specialized hardware that can't be easily replaced with a bolt from the local hardware store. These stepped, threaded steel axles with flats support the road wheels. An exploded view and completed assembly are shown on the right. The kit uses bronze bushings rather than bearings in most locations which is probably fine for something that will not move around that much. You would need many dozens of bearings to do a conversion. The axle shafts pass through the hull and are secured with nuts.

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Here is a selection (left) of the two sizes of return rollers with the bushings installed. On the right you can see these added to the hull. Note that I've also added the rubber wheels to the idlers. The road wheels will also get rubber tires, but the return rollers just get painted to look like rubber on the outer rim.

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Here is the pile of parts (left) which make up the simulated horizontal volute suspension. There are no real volute springs in the model, instead there are regular coil springs which sit inside cylindrical cans. These do a pretty good job of looking like volutes. The metal dampers on the far left are just for show; they offer no damping on the model. On the right you can see how the six suspension trucks are assembled (exploded view far lower right). Each truck has four wheels assembled in pairs attached to arms which pivot on the gudgeons attached to the hull.

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These pictures show the completed suspension. Each truck can rotate as a unit pushing one wheel pair up while another comes down without any shock compression at all. If both wheel pairs attached to a truck are pushed up at the same time then the spring and damper compress. The little boxes attached to each damper probably simulate fluid reservoirs.

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Installing the Drive System

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I think this is the first time I've seen the packaging used as part of a model. The manual instructs the builder to remove a cylindrical section of the the blister which previously contained an idler wheel (left) and use it to cover the exposed pinion of one of the motors (right). This becomes important later because there are wires very close to this location that could get sucked into the gearbox without protection.

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Here a series of hexagonal standoffs have been added to the bottom of the gearboxes. These mounting points are then used to attach the gearboxes to the hull as shown on the right. A pair of aluminum extensions are then attached to the hull to enclose the gearbox outputs with a long brass stiffener between them.

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This plastic front cover nicely represents the texture of a casting. On the right you can see a few details attached to the back of the hull including the engine access doors and the air filters. The bracket at the top center will hold the exhaust tips a bit later.

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Here's a little oddity. My kit came with an extra package (left picture, right blister) of B drive sprockets which are to be used to replace those in the main blister pack. I studied and compared them pretty carefully and I can't spot any difference between them and those that came in the main package. I did use them though, so now I guess I have an extra backup set of originals. The picture on the right shows the pre-assembled tracks. The treads are soft, rubbery plastic. The pins and connectors are metal.

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Now that the gearboxes and tracks have been installed, the "rolling chassis" is complete. I couldn't resist hooking up all the electronics as shown on the right and trying out the model to see how it drove. Note how much space is consumed by the speaker box. Both the DMD and the MF are contained in the hull and so is the battery. There is very little left for the turret except the tiny motors for rotation and elevation.



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I later built the Flakpanzer Gepard which came with old style metal tracks. Those tracks are actually from the original Sherman model in 1974 and are not correct for a Leopard derivative like the Gepard. I replaced the tracks on the Gepard with some aftermarket versions which freed up the metal tracks to be retrofitted onto my Sherman. You can see a comparison of the metal and plastic tracks here. I really like the sound that metal tracks make.


Completing the Model

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One of the tricks when building a tank is deciding when to do the painting. You can paint all the trees before building, but that takes a huge amount of paint. You can wait until after building, but there are certain bits that shouldn't be painted. I waited until I had the hull complete, then removed the tracks and the rubber tires from all the wheels, and painted everything olive drab. The outer parts of the return rollers don't have rubber tires so I had to manually paint them flat black as shown on the left. The reassembled and painted suspension is shown on the right. A couple of screws were left unpainted so I later touched them up by hand.

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Here is the completed lower hull with the suspension fully completed, all the electronics installed, and the wires cleaned up.

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The main hull part is marked "1974" which implies that it is made from the mold of the original model. However, it also says "56001" which was not the model number at the time it was released. It was originally "RT-1601" and was only renumbered years later. It also would not have had the "PS" (polystyrene) recycling label in 1974. Perhaps this is an updated version of the original mold. The picture on the right shows some of the molding detail including the casting texture and the welding bead. How they managed this level of detail in the mold so long ago I have no idea, but it is very impressive even now.

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I built the upper hull to this point before painting. The shovel is just set in place to show how the tools will later attach (see wrench, hammer, and axe sitting to the side). I'll have to hand paint these separately before attaching them. A lot of the detail is molded directly into the main hull part, but the lifting loops, rear storage rack, and light protectors are all separate parts (shown at left). The right hand picture shows the front details including the barrel rest, the machine gun, the light protectors, and the horn. Also note the individual diagonal brackets supporting the skirt. The barrel rest needs to be glued to the hull so it is not functional. The hatches do not open.

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These pictures show the details of the mechanism which rotates the turret. I suspect the bosses which support the rollers were the update made to the original mold that resulted in remarking it. The three black rollers center the turret and the gearbox engages a slew ring on the turret. In the right hand picture I've added the lights. The LED with the orange wires is for the fiber optic cable which is used for the muzzle flash of the machine gun. Five tiny incandescent bulbs are used for the headlights and tail lights.

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The black ring is smooth on the outside to ride on the turret rollers and center the turret. On the inside diameter are the gear teeth which mate with the rotation gearbox. The additional gearbox shown on the left is for barrel elevation. You can see the little black crank with a brass ball joint which will connect to a pushrod. On the right I've added the plastic parts which comprise the bottom of the turret. There is no provision for a thrust bearing to support the turret since this is an old design, so instead a slippery sticker ring will be placed on the bottom and used to reduce friction. Note the "2001" mark on the slew ring. This part was new for this latest version of the model.

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Now we can start on the upper part of the hull and the barrel mechanism. The bracket shown at left supports the barrel. You can see the silver crank in the rear which will attach to the elevation gearbox. On the right this has been glued into the turret.

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The barrel is molded in two parts which need to be glued together. The reflective tape I've added inside the end will help reflect the strobe light for muzzle flash. The completed barrel is shown at right, drying. If you look closely you can see some text molded into the casting. I first I was annoyed by this thinking Tamiya should not have made it visible, but then I found out this is the casting mark on the real tank. Good job with the detail Tamiya.

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On the left you can see that I've inserted the light into the barrel and secured the wires to the inside of the turret. On the right you can see the rest of the mechanisms installed. The tiny spring used to stabilize the barrel was particularly unpleasant to install. It is really important though. There is no counterbalance for the barrel, so without it there would be a lot of unwanted bounce. The turret is now complete except for the power switch which much pass up from the hull. The turret does not really need to be removed once installed because battery access is through the upper hull.

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Here I've attached a bunch of the details to the turret including antennas, a machine gun rest, and an open hatch (which can be built optionally closed). I won't pretend to be able to identify what all the detail parts are. I've also painted the turret olive green. On the right you can see the completed painting of the tools. This actually took a long time.

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That's it! Now that the turret is installed the model is functionally complete. I still need to add some accessories and do the detail painting.


Detailing and Weathering

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The tank may be done, but there are a lot of accessories to add. The picture on the left shows the extra helmets, road wheels,gas cans, ammunition boxes, ration crates, and the original machine gun. The picture on the right compares the original 1974 machine gun (olive drab) with the updated mold (steel gray).

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On the left you can see the limited number of decals I added. There are multiple marking options on the decal sheet. I chose markings for an M4 from the 711th Independent Tank Battalion of the 10th Army because this unit was stationed in the Pacific theater and therefore seems the most likely to be a version that would have been available for the Japanese folks at Tamiya to have studied. On the right you can see the accessories glued haphazardly to the back of the hull.

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The kit comes with an external radio antenna (left) which is not needed with a modern 2.4 GHz radio. Still, a real M4 is covered in various radio antennas so I trimmed the wire antenna short and inserted it as shown. I have no idea if it is even vaguely correct, but it looks pretty good. You can also see the installed machine gun.

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This tiny 1/16 scale driver figure required seven different shades of paint, many of which I did not have available and had to acquire. He came out pretty good except for my painting bane, the pupils. On the right I've added a bit of subtle weathering to the turret including metal paint on the hatch springs and some rust wash around the rivets and welds.

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Here I've applied a green wash to the entire side of the hull to simulate moss and/or mildew which made sense to me for a Pacific front M4. I also added rust and grease colored washes to the suspension and wheels as shown. This doesn't look filthy like a tank that has been through the mud, but I think it adds some important realism.

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On the right you can see my attempt at some rusty water running down the front of the hull and well as rust along the weld beads. Whether or not it was successful is subjective. I also added soot to the area around the exhaust in the rear, but you can't really see it in this dark picture (right).

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Here I've added more rust and grease weathering to the rear accessories. I like how it came out on the spare road wheels, looking like water has settled inside the rim and caused some rust. More detail is shown on the right.

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These two pictures show the completed model with the lights turned on. The lights are not particularly bright, but they show up well in a dark room.



Final Photos

I just love the way Tamiya tanks look when they are done. It looks good from any angle and, in certain terrain, is indistinguishable from the real thing.

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The real thing

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 Here are some comparisons with the real tank. There are so many variations of the M4 Sherman that it is very difficult to find one that is a perfect match. Each matches several characteristics but not others. This example has the right gun and plate hull, but the wrong suspension and track style. It also has no side skirt at all so the side looks a little different.


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This example has the right gun, plate hull, suspension, and tracks so it is pretty close. The skirt doesn't match though since it has the vertical extensions to protect the tracks.


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So close. This example has the right suspension, hull, skirt, and tracks, but the wrong gun. This appears to be the late model 76mm cannon.


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 This one might actually be right. The gun, hull, tracks, suspension, and skirt all look right.


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 In case there was any question as to how much detail Tamiya put into their scale models, even the casting mark was represented. Similar casting marks are present on the turret and hull.



Written by Eric Albrecht

Visit Eric's personal site with lots of build threads.


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