Vodnik's M103A1 kit information page

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M103A1 kit information page

Dragon Models Ltd. 3548
1/35

Some basic information first (from Hunnicutt's "Patton" and "Firepower" books):

M48A1 (sharing the same engine with M103A1):

length: without gun, w /fenders: 274.3 in (199.1 mm in 1/35)

M103A1:

length: without gun: 275.3 in (199.8 mm in 1/35)
gun overhang, gun forward: 166.9 in (121.1 mm in 1/35)

Actually the gun overhang above is a value for M103A2 - the value of M103 and M103A1 is given as 173.3", but I believe the smaller number for M103A2 is applicable to a later gun with the shorter muzzle ring as represented in the DML kit.

Surprise? Just 1 inch difference in overall hull length (with fenders)! It's only 0.7 mm in 1/35 scale.

So how was it possible if M103 had one more road wheel on each side? With three modifications:
1. extending the hull slightly at the front, moving the idler wheel forward
2. reducing distances between road wheels
3. moving the sprocket wheel to the rear

Now let's take a look at DML new kit dimensions (+/- 2mm accuracy of measurement):

length: without gun: 200 mm
gun overhang, gun forward: 100 mm

It looks like the hull length is almost spot on - yes, but...More about it later.

But what can be clearly seen from above numbers is that the main gun barrel is whopping 2 cm (20mm) too short! Okay, my measurements were not perfectly precise, as it is difficult to measure such three-dimensional object, but my error is not bigger than 2mms, so in the best case the gun is 1.8cm too short...

UPDATE: Thanks to Rob Skipper I now have some measurements taken from the real M103A1 tank. One of them is the length of the gun barrel from the rear of bore evacuator to the front of collar: 13' 7/8". This equals 3985 mm and in 1/35 scale it should be 114 mm. The same distance measured in DML barrel is 100.4 mm, i.e. 113.6 mm too short there. The rest of those missing 2 cm can be somewhere in the bore evacuator / muzzle area.

The ruler in these photos is at different height than the measured distance, so you cannot read the measurement from them (perspective error).
I just show these photos to prove that I have actually taken the measurements ;-)

Perspective error in the image below makes the barrel look longer than it actually is...

So let's get back to the hull length. In the real M48A1 the actual hull (w/o fenders) was a few inches shorter than the M103A1 hull - but M48A1 had fenders that protruded much more to the front of the tank than M103A1 fenders. Those fenders made the overall length of the M48A1 tank w/o gun almost the same as in M103A1.

M48A1 and M103 drawings from Hunnicutt's "Patton" and "Firepower" books.

Interesting fact is that the entire difference in length between the M48A1 hull and M103A1 hull (w/o fenders) was AT THE FRONT OF THE TANK - i.e. in front of the turret ring. The entire engine deck area (i.e. the distance from the turret ring to the hull rear edge) was exactly the same length in both tanks. The M103 hull had longer "nose" with thicker armor - i.e. the distance from the turret ring to the hull "nose" tip was a few inches longer in M103. Also the curvature of the "nose" (in overhead view - as on the drawings above) was not as big as in the M48 hull. The result was that the idler wheels were attached a few inches further forward than in M48. Shorter front fenders, compared to the M48A1 ones, however meant that the overall hull length was only slightly bigger (mentioned 1 inch).

So what DML designers did? Let's see:

Loooooooong engine deck in M103A1 part and identical front hull shape and length in both tanks...
Just the opposite of what it should be :-(
The difference in length is 11.5 mm.

UPDATE: Another measurement from Rob Skipper is the distance from the center of turret race to the hull nose. In real tank it is 112", what translates to 81 mm in 1/35 scale. In DML kit this distance is approx. 77 mm, so 4 mm too short for M103. This confirms the difference between M48 and M103 hull noses visible in drawings from the Hunnicutt's books above, which also translates to approx. 4 mm in 1/35 scale.

Identical nose shape in both hulls. WRONG!

Rear hull of M103 with attached part A1 which defines the shape of the front of engine deck area - as you can see it is a straight line, unlike the shape in M48A3 kit. No simple switching of engine decks is possible - not only the length is different, but the shape as well.

And this is how the M103A1 engine deck looks with part B2 attached:

Now if you try to attach part B2 to M48A3 kit hull... If you align it, so that is seats correctly at the rear of the hull:

It is way too long at the front:

And if you move it to the rear, the front of the part does not fit to the hull shape and the rear of the part extends far behind the hull edge:

Forget about swapping engine deck parts between these kits... :-(

Comparison between the Legend M48A1 conversion engine deck and DML M103A1 engine deck:

Note that DML long grilles along both sides of the hull have six hinged sections, each with its own handle, while Legend grilles only have five sections. DML is correct - Legend is wrong here. Unfortunately these grilles are too horizontal in DML kit, while they are correctly sloped toward hull sides in the Legend conversion.

Among measurements provided by Rob Skipper was a set of numbers describing distances between road wheels and between return rollers. Good news is that the DML kit is quite accurate in this aspect: the differences are no bigger than 0.7mm and in most cases much less than that.

Rob also measured the distance between the idler and sprocket wheels. Here the difference between the real tank and the kit is between 1.25 - 1.9 mm (as the idler wheel is adjustable, the distance on each side of the real tank was a bit different) with the kit wheels being a bit too close to each other. This confirms my observation regarding the sprocket wheel - it is attached in the same position as in the M48A3 kit (even though new larger final drive covers are provided in M103A1 kit), while in the real tank it should be a bit lower and further back.

One Rob's measurement that reveals the problem in the DML kit design is the distance between the idler wheel (left in this case) and the centerline of turret race. It should be 98 inches, what corresponds to 71.1 mm. But in DML kit this distance equals approx. 63 mm. So the difference is about 8 mm!

The image below shows four problems described earlier:

And the picture below shows what would have to be done to correct these problems: the curvature of the nose reduced, the turret race and driver's hatch moved to the rear and engine deck moved to the front and slightly shortened. The image is not exactly to scale - but it reasonably well shows the required changes. Note that in this drawing the position of idlers, road wheels and return rollers remained unchanged. Also note that the rear of the turret race is now (more or less) the same shape as in the M48A3 kit part and in Legend conversion part.

In the picture below you can see two problems: the turret is too far forward and the sprocket is too high (as evidenced by horizontal track section between the last return roller and sprocket wheel top.

Corrected turret and sprocket position. Note how tracks slope downward now. The tip of the hull nose should not be visible in front of the idler wheel like that in M103A1 - it is too long, as shown above.

In the photo below you can see the sloping track behind the last return roller and the position of the turret centerline (it is easy to find as the upward slope of the bustle bottom starts in that place, unlike in DML turret, but more on this later...)

Wrong position of the sprocket wheel is caused by the wrong axle position on the new final drive housing part:

Engine deck:

Note sideways sloping grilles along both sides of the hull - almost to the level of fender tops. But in DML kit we have this:

Taking the model photos above I noticed additional problem. Take a look at these pictures:

DML added an extra kink that shouldn't be there. Correcting this error without extending already much too long engine deck would require reducing the length of the lower hull.

Here are photos of the real M103/M103A1 rear plate:

And now a comparison picture: real (M103A2) and Dragon (M103A1) aligned using road wheels, as DML spaced them accurately:

Now a few words about the turret. Let's put the turret on the hull and... wait a second... WTF?!...

Amazing engineering... Wouldn't you agree that it'd be nice if someone at Dragon had built the kit at least once before they started selling it?...

I managed to force the turret in the neutral position:

As you can see the bottom of the DML turret is concave. So there is enough space under it for the exhaust deflector in the center, but not at turret sides. The exhaust pipe detail is included in the kit, I just not attached it.

On the photo above you can clearly see the bulge at the bottom of turret bustle. It is in the center of turret.

But in reality... It was not. It was actually on the right side of the turret:

You can also see in above photos that the bustle bottom is flat, not concave.

Picture below shows two problems: the shape behind the mantlet and wrong shape of the bustle bottom.

Note the inverted V shape of the turret top:

Not present in DML turret...

OK, that's enough... I could now go on describing all the incorrect details, but it is not the point of this text. I only wanted to show the major shape and dimensional errors.

One more thing: BIG THANK YOU TO DRAGON MODELS LIMITED FOR THE SAMPLE KIT!

FINAL NOTE: With a lot of work a reasonably accurate M103A1 model can be built, but once you get to that point there is very little left from the original Dragon kit... See here: M103A1 gallery.