T-72M
Model of a Cold-War era Soviet main battle tank. Features suspension, rotated turret, elevated main cannon and lights.
Datasheet:
Completion date: 10/09/2011
Power: electric (Power Functions)
Dimensions: length 39 studs (52 studs including main cannon’s barrel) / width 19 studs / height 16 studs (not including antenna)
Weight: 1.057 kg
Suspension: torsion bars
Propulsion: 2 x PF Medium geared 1:1
Motors: 3 x PF Medium, 1 x micromotor
Top speed: 1.14 kmph
T-72 is one of the most popular tanks in the modern world. It has been produced for 40 years now, and the production still continues with over 25,000 total tanks built. It was designed with cheap mass production and maintenance in mind. It offers interesting blend of simplicity and good characteristics, and it generally follows the Soviet doctrine of focusing on quantity rather than quality of tanks. While the T-72s can be easily gathered in large numbers, they usually lose 1:1 encounters with Western tanks.
I have chosen this particular tank because it’s a great example of Cold-War era Soviet tank design, with flattened hull and small, bowl-shaped turret. The US intelligence nicknamed the turret “Dolly Parton” because its shape supposedly reminded her breasts (you are strongly advised NOT TO search for photos of Dolly Parton, for the sake of your good taste). I had two goals while building it: to test the torsion bars suspension in a lightweight model, and to see how small fully motorized tank model can I build.
As for the aesthetic side, there was a number of minor shortcomings. I wanted to properly model the distinctive shape of the turret, because Lego models of the T-72 usually have turret shaped like a slightly gnawed disc. I think I achieved that, at the cost of attaching some details to the bottom of the turret, thus increasing the gap between the turret and the hull’s upper surface. The turret also had very little space inside – so little, in fact, that the majority of the main cannon elevation system had to fit in a 2 studs wide gap.
Other than that, the central section of the main cannon’s barrel should have been slightly thicker, but the only idea that occurred to me was to wrap it in a paper of similar colour and let it pass for a sticker. I also had the impression that the hull is slightly too tall, even though I was sure it had the right proportions. I could have remedied it easily by decreasing the suspension’s angle and thus the ground clearance, lowering the entire tank, but the large ground clearance is distinctive for the T-72. Perhaps the reason was that the side skirts started a little higher than they do in the real tank.
The T-72 is unusual in how its details are distributed: there is a lot of details on top of the hull’s rear, but almost nothing on the side skirts and above the tracks. I have added some extra details to simulate the kind of “luggage” that some tanks carry on them – in some cases it seems that the tank’s crew grabs virtually anything that comes around and attaches it to the armour. I have also used Lego LEDs to emphasize the large number of searchlights on the turret, which is very distinctive for the T-72, and I used some Lego plants to simulate the so-called environmental camouflage, just to see the result.
The model was very simple technically. There were two PF Medium motors in the back, connected straight to the rear tension wheels. Together they provided reasonable speed and a surprisingly high torque. The were also two IR receivers in the back, and another PF Medium motor between them, used to rotate the turret. Because of how small the turret was, its entire rotation system along with the turntable was located in the hull. The central part of the hull was taken by the turntable, and the front was taken by the 8878 battery lying transversely on its side. The battery could be accessed by removing the entire glacis plate. The remaining space, which was sparse, was taken by wires and the suspension system.
This was my second tank to use torsion bars suspension – the previous one was almost 3.5 kg heavy, with nearly 0.25 kg load per road wheel, and its suspension worked perfectly. Here the suspension was very similar, except that the axles used as the torsion bars were kept at fixed angle by the toothed half-bushes and toothed connector joints. It saved some space, but it wasn’t working really well because there were gaps at the half-bushes, which I had to fill with tiny scraps of paper. The average load was less than 90 grams per road wheel, and the entire suspension was therefore very hard – it was actually difficult to notice that it works.
I was happy with how the model turned out, even though its aesthetic side had a few compromises to it. It was a good, very agile model to play with, but I think it proved too light for this kind of suspension.
