Re-edition of the model of the Swedish MBT, built two years after the initial version. Features full suspension, remotely tilted hull, remotely controlled dozer blade and lights.

Datasheet:

Completion date: 06/03/2010
Power: electric (Power Functions)
Dimensions: length 67 studs (including main gun’s barrel) / width 25 studs / height 19 studs
Weight: 2.15 kg
Suspension: pendular bogies
Motors: 2 x PF Medium, 2 x PF XL

After almost exactly 2 years, I decided to re-build my perhaps most renown tank model. The S Tank, created back in 2008, has been extremely well welcomed, and no matter how many bigger, more accurate and more complex tank models I’ve built later, there were always some people claiming that S Tank was the best. I, on the other hand, was aware of many shortcomings of this model, and it was my goal to overcome these shortcomings in the following models – a fact that has apparently escaped the attention of many S Tank’s enthusiasts. Eventually, I decided to build this model again using my current level of modeling skills, even though it was against my ‘never build the same thing twice’ rule.

The original S Tank, or Stridsvagn 103, is a fascinating machine all by itself. Designed in 50s, it was the main tank of the Swedish army for the next 40 years, until arrival of the Leopard 2. What was the key of its success and its long-term service? The fact that it was designed with Sweden in mind. Moreover, it was designed specifically for defensive roles. This is why the typical turret was removed completely, because the tank was intended to stay hidden waiting for the enemy to come. To operate in difficult Swedish terrain, the tank was fitted with then-advanced hydropneumatic suspension and a turbine engine (in addition to a traditional diesel engine), making it the world’s first MBT to use turbine engine. Aiming was done by moving the entire tank, using the suspension to tilt the hull as needed. In order to fire its main gun, the tank had to be stopped and its suspension locked – it was clearly a drawback, but it was acceptable given the tank’s defensive role. It should be also noted that in 50s and 60s the fire control systems were relatively primitive, and tanks rarely fired while moving. Finally, the S Tank was equipped with a front dozer blade, which could be used to entrench it quickly and without the need for crew to leave the vehicle.

Thanks to removal of the turret, the tank’s front could be protected by a single armored plate, set at an angle that made it very difficult to penetrate. Actually, at the time it was designed, the S Tank’s front armor was virtually impenetrable for any other tank’s armament. To make a full use of this advantage, the crew included two drivers – the second driver was facing backwards and had his own set of steering instruments. Thus the S Tank was able to drive backwards quickly, while being protected from the enemy by its front armor, as well as being able to return fire at any time.

The S Tank was clearly an unorthodox design, so specific that Sweden remained its only operator, but it could be pretty lethal to any advancing force. Why? Because it had to be spotted before it could be engaged. Now, take a good look at a fully entrenched S Tank:

The new model of the S Tank was supposed to be: accurate, performing well and dark gray. I believe it meets all these conditions. The hull, which was tilted pneumatically in the previous version, is now controlled by linear actuators. It takes much more hull’s internal space, but the stability provided by such solution is peerless. Since my first S Tank was driven by a single XL motor, and the motor was apparently working pretty hard, and now the PF speed control is available, I used two XL motors, each one driving a single track. The tracks’ suspension system consists of 4 large, realistic road wheels (6595 wheels without tires work very well with tracks) suspended on pendular bogies, two wheels per a single bogie. I wanted to use a torsion bars suspension for the first time, but it was impossible to make it work together with the tilted hull. The front dozer blade is operated by a single PF Medium motor instead of pneumatics, and it works better than I expected (this is an application where pneumatics usually performs better than motors do). It should be noted that front part of teh hull houses a traditional battery box rather than the rechargeable battery, and there are two reasons for that. Firstly, a battery box can provide more power for two PF XLs used simultaneously, and secondly I needed something heavy in model’s front part to acquire the proper weight distribution.

As for the visual details of the model, my goal was to model the most distinctive ones. Like many tanks with long service period, the S Tank has undergone several modifications and there are 4 variants of this tank, which differ mainly in details. Few details are fictional, just to fill some empty spaces. Please note that this model uses custom chrome sprocket wheels, rather than original ones that come only in yellow or orange at the moment. These wheels have been purchased at this Bricklink store.

The model took a lot of work and a lot of extra shopping for parts, but I think it was worth it. For me, it is clearly my best-looking tank up to date. It seems that models in dark gray look particularly well on photographs, which is why I attempted to make a couple of macro-like shots, even though I only had a general purpose lenses (macro lenses are expensive beyond human reason). The model performed very well too – it was my fastest tank up to date, and its large road wheels made the suspension’s work spectacular to watch. I have enjoyed driving it over a wrinkled blanket more than I enjoyed driving any other tank under any other conditions. However, there’s a good chance that it would perform better with a torsion bars suspension.

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Model of the American WW2 super heavy tank prototype. Features full suspension, drivetrain with a subtractor, lights and advanced main gun control system.

Datasheet:

Completion date: 13/02/2010
Power: electric (Power Functions)
Dimensions:  length 73 studs (including main gun’s barrel) / width 30 studs / height 16 studs (not including aerials)
Weight: 2.2 kg
Suspension: pendular bogies
Motors: 2 x PF Medium, 2 x PF XL

T28 was an unusual project. Started in Spring 1945, it was designed to break through German defenses and to counter German super heavy tanks such as Maus or E100 (none completed, fortunately). The designers focused on the armament and armour of the tank at the cost of its mobility, and they decided not to use a typical turret as it would not be needed against fortifications. T28 had one of the thickest tank armours in history, but it was driven by an V8 engine providing merely 500 HP – a very little power for a tank of such weight. It was also one of few tanks to move around on 4 tracks. The outer set of tracks could be removed for transportation by train. The tank could drive on a road on inner tracks, towing the outer ones behind.

Out of 25 planned T28s, only two were built. The war ended before they were operational, and in 1947 they were subjected to evaluation. It went bad – one prototype was completely destroyed by engine fire, and the other one proved that a 500 HP engine can barely move it. Both were supposed to be scrapped, but the undamaged one was found in 1974 in a back field at Fort Belvoir, Virginia. It is unknown where it was earlier, and it is unknown how a tank of this size can remain unnoticed inside a military base

The model is relatively simple on the technical side. It uses only 4 motors, two to drive and the other two to control the main gun. Just like in the real tank, the main gun has limited traverse and elevation. The drivetrain consists of a subtractor and two PF XL motors, one for drive and one for steering, on assumption that it takes quite a torque to steer a tank that wide and with 4 tracks. The model is not entirely accurate – one of departures include a V6 piston engine in the back, instead of fuel tanks. The real machine was driven by V8 engine, but only 6 pistons can be seen through a 8×8 grill, so I used a V6 engine. It has internal lighting, with lights pointed at each piston, and all the lights are coupled with the drive engine, so the faster tank goes, the brighter the engine is.

Another departure is the shape of the front of the hull. It was changed mainly to house the main gun control mechanism. The real tank had its gun mantlet attached to the hull, while the model’s mantlet is attached to the barrel and moves together with it, hence it needs a certain margin of free space around it.

The most challenging element of the model was its suspension system – not because it’s advanced, but because it’s so expanded. Each of the four tracks uses four pendular bogies, each with two road wheels. It sums up to the total of 16 bogies with 32 road wheels. Each track’s suspension is separate and independent, and each track consists of 123 tread links. Together with the spare track section on the armour, it sums up to over 500 tread links used for the model.

The model looked really well, and it definitely paid off to build it in dark grey instead black. It performed well, although the main gun’s barrel was a bit wobbly. It also seemed to experience problems with the drive motor – it could drive backwards and turn very well, but it seemed that driving forwards put more and more tension on the motor. The problem seemed to be getting worse over time, and it is possible that the PF XL motor used for drive was defective. Because of that, the model appeared very slow on the video, whereas given a properly functioning motor it should have been faster. Still, it was my first tank in dark grey, and came highly acclaimed for its look.

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Model of a modern French main battle tank. Features advanced independent suspension with adjustable ground clearance, gearless drivetrain, remotely rotated turret and commander’s gun, remotely elevated main gun, and an onboard wireless live feed cam.

Datasheet:

Completion date: 17/08/2009
Power: electric (Power Functions)
Dimensions:  length 58 studs (including barrel) / width 26 studs / height 22 studs (plus aerials)
Weight: 2.48 kg
Suspension:  full independent with adjustable ground clearance
Motors: 4x PF Medium, 2x PF XL

I have a special liking for the tracked vehicles, and especially for modern tanks which happen to be the most advanced tracked vehicles ever built. This is why, having built my last tank nearly a year ago, I was looking for a modern machine that would make a nice model. I wanted something similar to the previous model, the Abrams M1A2 tank, but smaller, lighter and more mobile. Since the Leopard was out of the question (I wouldn’t feel comfortable building a German tank), and the Merkava has an unusually shaped turret that would be difficult to model, I decided to build the Leclerc – a very good and distinctive example of today’s high-tech tank.

If we lay aside the popular jokes on French tanks, the Leclerc is a fairly outstanding and impressive machine. It was build for a very interesting reason: because none of the world’s tank lived up to the expectations of the French Army. As one may anticipate from that, it is in many ways different than earlier main battle tanks such as e.g. Abrams, and very likely sets standards for the future constructions.  There are differences in almost every aspect of its construction: for example when it comes to the defence, Leclerc’s design focuses strongly on the active protection. The tank is protected passively by a modular armour similiar to the one used in Leopard 2, but there are two layers of active protection being currently developed and scheduled to be put into use around 2015: the ‘soft’ layer is capable of jamming computer systems of the incoming missiles, while the ‘hard’ layer shoots down any incoming large-caliber projectiles. Both layers are supposed to be fully automated, with the latter one being capable of shooting down projectiles coming from any direction in time intervals as short as 0.6 second. Even Leclerc’s armament is unusual: instead of Rheinmetall 120mm cannon present in vast majority of modern tanks, it uses longer French-built GIAT 120mm cannon along with a custom French-produced ammunition and an automatic compressed air fume extraction system instead of the usual bore evacuator. The tank’s turret is built around an autoloader system designed specifically for Leclerc, which provides an impressive performance and at the same time allows to avoid many problems usually present with the standard autoloader systems. The most impressive things are many high-tech upgrades scheduled for the Leclerc: those include the aforementioned two layers of the active protection, but also multipurpose armour upgrades, the anti-missile decoys deployment systems, thermal signature reducers, and – probably the most impressive of all – Stealth armour kit.

The construction of the model started with a new suspension concept. I was happy with the performance of the independent suspension used in my Abrams model, but I wanted to make it even more realistic. In order to achieve it I have removed the most unrealistic element, the central tread wheels , and I fitted all the road wheels with thin full rubber tires. Thus the tracks have no solid point of contact with any road wheel whatsoever, and are kept in place only by the road wheels, without any use of the tread wheels which are commonly used in the official Lego sets. At first it seemed an unreliable solution, but it proved to be perfectly reliable – I had less slipped track cases with Leclerc than I have had with the Abrams, and they all happened only because the tread links came apart.

It was obvious from the beginning that the model will make use of the new 8878 rechargeable battery and of the PF speed control feature. It meant two things: that it will have plenty of internal hull space available, and a very simple drivetrain. I have eventually limited the drivetrain to just two short axles connecting motors directly to the respective drive wheels – with the speed control feature nothing more was needed to allow the tank to make turns at any angle, and it seemed to blend power with speed in a promising way. Moreover, such a drivetrain was extremely efficient and durable, since not a single gear was used.

With a lot of internal hull space at hand, I wanted to try an idea of using the independent suspension to adjust the ground clearance. It was achieved by mounting upper tips of all the shock absorbers on lengthwise liftarms, which were moved higher or lower by two coupled pairs of very short levers. That solution worked very well in the early construction stage, easily providing two studs of difference in ground clearance, at which rate the tank was actually able to sit on the ground. It was also possible to change ground clearance at any position, at any moment, even while driving, and the tank’s suspension remained fully functional all the time. The efficiency of this system, which took almost half of the internal hull’s space (there were 4 sets of worm gears all coupled together), was eventually severely crippled by two factors: firstly, the length of the tracks which was limited. The tracks weren’t, obviously, elastic, so their length remained the same as the suspension was raised or lowered. It left a small margin for differences, as the tracks couldn’t be too lose or too tight, and so the range of ground clearance adjustment was limited to approximately single stud. The latter factor was simply the model’s weight, which proved larger than expected and heavily loaded the mechanics of the ground clearance adjustment system. Even though the Leclerc was still much lighter than Abrams, its suspension was loaded a bit heavier because it consisted of just 12 sets of road wheels compared to Abrams’ 14 sets.

The remaining hull space was used to house the battery (in front of the hull, with a small access hatch in the armour under the front part of the turret), three IR receivers (located next to drive motors, partially below rear part of the turret) and a PF Medium motor controlling the turret’s rotation. The last solution was unusual for my tank models, as the previous ones had this mechanism housed inside the turret itself. It made the turret’s internal structure a lot simplier, which was important to me because I wanted very much to model its distinctively flattened silhouette. Thus, the turret ended up housing two PF Medium motors, first of which was used to elevate the main gun. The elevation system used a single linear actuator, much like in the Abrams model, except this time it was located in a central position to make the main gun’s barrel more stable. As for the latter PF Medium motor, I initially intended to use it for a main gun recoil system, an improved version of the one used in the Abrams, but I have eventually decided not to make these two models more similar to each other than they already were. It left me with just a few possible options to use the extra motor, so the motor was eventually used to make a ‘turret in a turret’, that is to rotate commander’s gun, which is a nod towards the realism as the real Leclerc has this gun controlled remotely from inside the tank. Thanks to that, there was a lot of space left inside the other side of the turret, which I have used for something I wanted to use already in Abrams – an onboard live feed camera showing forward view from the turret. I have used a simple micro industrial surveillance wireless camera, exactly the one used much earlier in my Moon Rover. It fit inside the turret very well, and I was particularly pleased with the sound recorded from inside the model – the sound of moving tracks seemed more realistic than I could have ever imagined.

The model enjoyed a fairly good reception. I didn’t really like its aesthetic side which seemed too much like that of the Abrams model, but I loved the performance provided by the powerful drivetrain and the sophisticated suspension system. It seemed to have all the impressive power of Abram’s drivetrain, but moved much more swiftly and fluently. It was my fastest tank model at this weight and the first one to use Power Functions speed control feature.

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Fictional 6×6 IFV. Features all wheel drive, full independent suspension, illuminated piston engine, deployable side cannons, and tank-like turret with ability to shoot projectiles.

Datasheet:

Completion date: 31/05/2009
Power: electric (Power Functions)
Dimensions:  length 61 studs / width 28 studs / height 30 studs
Weight: 2.78 kg
Suspension:  full independent
Motors: 2 x PF XL, 4 x PF Medium, 1 x 71427

The initial inspiration for this vehicle was GoW’s Laverne APC. I did not regard its construction as realistic, so I’ve made many changes, including different axles setup.

There was a number of experimental features built into this construction. Among others, I wanted to see how a full independent suspension performs in a 6×6 vehicle with considerable weight. It turned out that only one steered axle in such a vehicle is a bad solution, because the wheels on the rear axles bend while turning. The axles #2 and #3 use 3 studs wide differential bracings I have developed some time ago, and they worked flawlessly. Axle #1 on the other hand is exactly the same module that has been used in my Hellbender model.

Another important feature is the turret. It’s ugly and large (which makes it look like the turrets of self-propelled howitzers) but it houses a firing mechanism developed by Duku and used previously in my Tripod Gun. The mechanism was initially supposed to shoot projectiles through the barrel, but the prototypical barrel made of 1×3 liftarms had so large internal friction that the projectiles couldn’t even exit it. Hence the barrel is non-functional, and the projectiles are being fired from above it. The entire mechanism along with the barrel can be elevated by a linear actuator, but since there is little place under the turret, the elevation is only by few degrees. It shows that if I want to use such a turret in a model of a tank, it needs to be partially ‘submerged’ into the hull to reduce its height.

There are two additional small turrets on the front part of the hull, which rotate accordingly to the front wheels’ angle. However, the synchronization with the steering mechanism is poor.

Finally, there are two deployable side cannons. The initial idea was to use links and a complex setup of several independently moved parts to make the cannons emerge from inside the hull. As the hull’s construction progressed, the available space was becoming more and more limited, so the cannons have eventually ended up in simple casings deployed like a drawbridge. This is a very simple solution, and both casings are moved by a single string and internal winch. In order to solve the problem of string’s backlash, the string was not fixed to the winch drum – instead, it goes through it. Thus the backlash is distributed evenly on both sides of the winch and reduced whenever the string is pulled up.

Personally, I regard this construction a complete aesthetical failure. Still, it featured a couple of new solutions, it was my first vehicle able to shoot and the first wheeled vehicle that used the Power Functions speed control feature.

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Model of my favourite vehicle from the Unreal Tournament 3 game. Features 4×4 drive, full suspension, pneumatic rear differential lock, rotating front & rear turret, lights and custom stickers.

Datasheet:

Completion date: 24/03/2009
Power: electric (Power Functions) / pneumatic (fed from internal electric compressor)
Dimensions:  length 46 studs / width 29 studs / height 30 studs
Weight: 2.35 kg
Suspension:  front – independent / rear –  live axle
Motors: 3 x PF Medium, 1 x PF XL
Pneumatics: a single circuit with an autovalve fed from a dual-pump internal compressor

Being an ardent fan of the Unreal Tournament series, I have finally decided to join two passions and build a model of my favourite UT vehicle. Which is Hellbender, underestimated by many, but absolutely lethal if used properly. It was also an opportunity to test a suspension I have developed with Truck Trial races in mind, as well as the 3 studs wide differential lock mechanism I have recently published.

The model is certainly not 100% accurate, as the original vehicle was quite challenging to reproduce. It is, however, entirely functional and fitted with 4 motors total. Power is delivered from two battery boxes, not because of some particularly high energy consumption, but because it turned out to be optimal to locate the battery box on the side, so I have used two battery boxes, one counterbalancing the other. The 4×4 drive is powered by a PF XL motor, and the steering is operated by PF Medium one. Another Medium motor rotates two turrets synchronously. The third Medium motor drives a dual-pump internal compressor via an autovalve, thus controlling the differential lock mechanism in the rear axle. As the rear axle is floating and quite complex already, I found it to be an optimal solution – thus, almost entire pneumatic system is located inside the hull, and there is only a sinle small pneumatic cylinder with two pneumatic hoses in the rear axle.

As for the off-road performance, the model certainly suffers from a short chassis and perhaps too complex rear axle. The short chassis was the reason why the drivetrain is complicated, with steering system located behind the front axle, and the drive being transferred to it from the front. A single, common driveshaft located in the center of the chassis would certainly perform better, as it is a popular solution in the Truck Trial vehicles. The rear axle, on the other hand, has its differential mounted not steadily enough because of the lock mechanism, which results in the gears’ tendency to snap. The model performs well on the floor, but has difficulties with even easy obstacles. It is, however, an interesting study of how the independent suspension based on the 8297 set’s components performs.

The model was presented by me at the official UT3 forums, where it has been acclaimed by some members of the Epic staff.

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Media reference:

BeyondUnreal

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Functional model of the APC from the James Cameron’s Aliens movie. Features 4×4 drive & steering, full suspension, remotely opened side slidedoor, manually opened driver’s door, remotely rotated turrets, lights and custom stickers.

Datasheet:

Completion date: 11/12/2008
Power: electric (Power Functions)
Dimensions:  length 61 studs / width 22 studs / height 19 studs
Weight:  2.49 kg
Suspension:  pendular with shock absorbers
Motors: 2 x 71427, 2 x PF Medium, 1 x PF XL

My first stricly movie-inspired model, preceded by a long period of a meticulous documentation. I’ve been planning to build it for over a year, and still had to do a lot of shopping before I started. Eventually, it turned out to be my most rare-parts-consuming project up to date.

The model can’t be described without an important point of reference – a model of the same vehicle built earlier by LUGPol user Havoc.  Havoc’s version was not functional, but had quite an accurate appearance, and featured full detailed  interior. My goal was to build a model of the same size, but fully functional. I did not’ however, rely much on the appearance of Havoc’s APC, and built many details in a different way, trying to introduce a number of my own improvements. Overall, my model had less and simplier small details, but better and more accurate silhouette. It was quite amusing to eventually learn that both versions had nearly identical weight.

I have started by choosing a different wheels than Havoc did. The 8448 set’s wheels were better suited in my opinion, because even though they lacked a military-style appearance, they looked very well with 8×8 dishes, and they offered a precious space for the suspension inside. I have used two identical suspension modules, partially based on my pendular steered & driven suspension module, but smaller and fitted with the 3-studs wide differentials. Each module was stabilized by a pair of shock absorbers, and the direction of driveshaft’s rotation was reverted in the middle of the hull, to neutralize the torque effect present in pendular suspensions. The steering lock was limited by the mudguards, but with both axles steered it sumed up very well. While the original vehicle was built from a pushback tug with the crab steering mode present, such a mode did not appear in the movie, and therefore I did not attempt to recreate it.

Full pendular suspension along with a longitudinal driveshaft and steering shaft crossing the middle of the hull has caused a major stability issue. Normally, a pendular suspension is fully stable as long as right and left sides of the vehicle have equal weights. Here, limited size of the hull and imposed location of internal mechanics did not allow me to place the heaviest internal components, that is the battery box plus drive and steering motors, in the middle of the hull. Instead, all internal components had to be moved to one of the vehicle’s sides. Therefore sides of the model had unequal weights, which I have almost fully compensated with nearly 200 grams of additional ballast on the model’s right side, next to the slidedoor.

As for the slidedoor, it was moved by a simple rack & pinion mechanism driven by a 71427 motor. Thanks to the use of safety clutch, it could be also moved manually at any time. The inertia that appears while this type of motor is stopping had added an unintentional effect that made the door appear heavy. The door’s construction turned out to be much more tricky than I have expected, as I was determined to build the door from plates, and therefore it lacked some stiffness. I have solved this problem by using a long horizontal rail attached to the bottom of the door, and additional short upper rail, that kept top of the door pressed against the hull. It required a small horizontal opening in the hull’s lower side, but worked very smoothly.

The rear turret was a tought matter, as it can be slided back to the APC’s rear wall in the movie. I have considered a number of ways to recreate such a movement, taking into account mainly the use of a chain & tread links. The limited size of the model, plus the amount of space occupied by its suspension made me drop that idea completely – such a chain would require at least 16-teeth gears to put it on, and the space behind the rear suspension barely sufficed for the steering system. Moreover, even with the space issue solved, it would be very difficult to make the turred slide steadily while mounted on such a loose structure as the chain. It would be very likely hung at angle while slided back, due to the backlash in the chain. To deal with it, a complex system of rails would have to be employed, resulting in an even greater need for internal hull space. Having considered that, I have used a turret able to rotate, but not slide, and made the rails on the back of the hull appear acid-soaked. Thus the immobility of the turret, which was inconsistent with the movie, could at least be explained in a movie-related way.

Both front & rear turret were rotated by separate motors through a safety clutches. I have used two various motors because of the very limited internal space in the hull’s front part, but both motors ran at similar speeds and rotated the turrets through exactly the same gear ratio. It resulted in very similar speeds of the turrets’ roration, and their independent movement if one of them became locked (which was inevitable in case of the front turret, whose range of rotation was limited by the hull).

The hull was built in a very non-Technic way. I wanted it to appear reasonably smooth – which meant for me using smooth surfaces where possible, but not trying to cover every single stud. This is well seen in the case of the top armour, which was fully covered with tiles in Havoc’s version while I attempted to use large tiles with studs on sides to render the pattern of riveted armour plates.

I have used a large number of stickers to decorate the hull, larger than the original vehicle had, on assumption that a military combat vehicle must bear a number of markings. Stickers in the front part of the APC were consistent with the original ones, and I have found and used military badges designed for the movie in some of the other stickers.

The model was warmly received, and many viewers considered it better-looking than the earlier Havoc’s version. The colour issue was brought up, and I agreed that the model would look better in dark grey, but it would be much more expensive and difficult to build, and still remain somewhat inconsistent with the movie where the original APC’s colour was a very dark green. I have, however, made the model unicoloured, just like the original one was. As for the performance, the model went through a lot of test-driving and performed very well, although its off-road capabilities were greatly limited by the very small ground clearance. Still, it was easy to drive and manoeuvre, and had plenty of torque. I’ve kept its speed low because it runs at such speed through the most of the movie, and I was afraid that it would be very difficult to access the drivetrain, should it malfunction while starting or stopping such a heavy model at a high speed.

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Media reference:

Klocki, JoeMonster

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Successor of the Challenger 2 model. Features advanced suspension system, dual 2-speed remote controlled gearbox, remotely rotated turret and elevated gun, main gun recoil mechanism, battery box sledge mounting system, custom stickers and lights.

Datasheet:

Completion date: 17/10/2008
Power: electric (Power Functions)
Dimensions:  length 74 studs / width 26 studs / height 18 studs
Weight: 2.83 kg
Suspension:  full independent with separate shock absorbers for each road wheel
Motors: 5 x PF Medium, 2 x PF XL

While building my Challenger 2 model, I got plenty of new ideas, some of which had to be dropped because of the limited size of the model. I don’t usually like to build two constructions of the same type in a row, but in this case the number of these ideas was so large that I’ve immediately started to build another, bigger model with newer treads system.

The suspension system was pretty much the same, except it used tread wheels of the newer tread system, seven road wheels on each side of the tank, and shock absorbers of three different, mixed hardnesses (compared to two hardnesses in the Challenger 2). This time the hull size was kept accurate, and was not deformed by the suspension system. The radius of the road wheels was slightly smaller than imposed by the scale (3 studs instead of 4).

The drivetrain, on the other hand, was completely different. It didn’t use any form of subtractor – instead, a single PF XL motor drove each track via a driving ring-based 2-speed gearbox. The gearbox could be actually called two gearboxes, as it consisted of two identical, independent modules. Each of these modules was controlled by a PF Medium motor, which resulted in the possibility to remotely change gears for left and right tank’s track independently. The gear ratios of both gears differed three times. If we include turning in place, it means that the gearboxes offered 10 possible combinations of the model’s turning radius. This was, however, somewhat inconvenient in practice, and the separate speed control of each XL motor would certainly be a better solution.

Gearbox was located at the back of the hull, inside a special chamber with internal lighting and 8×8 plate with grill on the top, so that it could be easily seen what gears are currently selected. The top grill plate was mounted in such a way, that it served as an easy access hatch in case if any problems with changing gears should occur (which never happened). Nearer to the middle of the hull were two XL motors, and then two Medium motors that controlled the gearbox (both with safety clutches). Front part of the hull housed a battery box with a special sledge mounting system. Thanks to that system, the box was firmly installed inside the hull, but could be removed from below in a matter of seconds. Moreover, the system was only slightly larger than the box itself, and didn’t require any extra parts to be attached to the box. Finally, the very front of the hull housed three of four model’s IR receivers.

The turret’s construction was based majorly on the turret of the Challenger 2. It housed three Medium motors, one IR receiver,  and a single linear actuator. It was powered from the hull via two wires, which granted large rotation freedom. One motor with a safety clutch was used to rotate the turret, and it could be rotated through 360 degrees, although not as smoothly as the Challenger’s turret because of the worse weight distribution (the rear of the turret was much heavier than the front). The other motor powered linear actuator that controlled the main gun’s elevation, exactly in the same way as in the Challenger. The third motor controlled the main gun recoil system. It consisted of a motorized eccentric mechanism with a string attached in such a manner that the string was continuously pulled back time by time. The other end of the string was attached to the main gun’s cradle, which provided 1 stud of longitudinal movement and contained a rubber band that worked against the string. Thus, with the recoil system engaged, the main gun was pulled back by the string, and then moved back forth by the rubber band. It happened in continous cycles, regardless of the gun’s elevation. One drawback of this solution was that the gun was somewhat unstable, and vibrated while driving. This effect could be, however, greatly reduced in case of a shorter and lighter gun.

I was very happy with the final look and performance of the model. While unstable main gun looked a bit ridiculous, the tank made up for it with the flawlessly working suspension and drivetrain. Using shock absorbers of different hardnesses was a good solution, although the last pair of road wheels was troublesome to suspend (it needed hard shock absorbers to not yield to the model’s weight while driving forwards, but such absorbers only worked a little bit on the obstacles). Driving the model with two XL motors was a good idea too, it is clearly seen on the video that such a drivetrain was quite powerful, despite the tank’s weight. It should be noted that it was difficult to make the model turn in place on any not-really-smooth surface, probably because of the tracks’ length. Still, it was quite an advanced and well-functioning model, and for some time I have even considered it an ultimate level of how far a tank model can be developed. Which was obviously not true Additionally, it was my first model photographed with professional lighting and against a professional background – especially the lighting greatly increased the quality of final pictures.

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Media reference:

Klocki

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First of my new generation of tank models. Features full independent suspension with shock absorbers, drivetrain with a subtractor, lights, custom stickers, turret rotated through 360 degrees, and main gun elevated by a linear actuator.

Datasheet:

Completion date: 04/10/2008
Power: electric (Power Functions)
Dimensions:  length 55 studs / width 20 studs / height 15 studs
Weight: 1.58 kg
Suspension:  full independent with separate shock absorbers for each road wheel
Motors: 3 x PF Medium, 1 x PF XL

My third model of an actual tank, and the beginning of an entirely new generation of tank models. It has set several standards which I’ve struggled to preserve in later models, such as realistic advanced suspension system (unlike simple pendular bogies in earlier tanks), custom stickers and lights. It was also quite compact considering the number of technical features included.

The suspension system was based on an actual number of the original tank’s road wheels, all suspended independently. 24-teeth gears have been used as tread wheels, enclosed in Technic triangles and suspended on a separate shock absorbers. I have spent a considerable amount of time developing a suspension system that would allow to locate wheels of this size only 1 stud away from each other (as imposed by the scale) and still preserve a good travel distance of the suspension. Eventually, it turned out to be possible, but only with wheels and shock absorbers set at a very specific angle. As a result, suspension required a certain amount of vertical space inside the hull, and it was impossible to use smaller amount. This led to major deformation of the model – its hull is simply taller than it should be, in order to fit the suspension system in. It has degraded the look of the model, but worked flawlessly.

The internal structure of the hull was more typical – with a longitudinal subtractor in the rear part, and a battery box in the front. The model  was so small that it was necessary to make a hole in the hull’s side to fit the battery box in. The subtractor used a PF XL motor for drive and PF Medium motor for steering. Two IR receivers were located in the top-front part of the hull, next to the battery box.

The construction of the turret was, on the contrary, very innovative, and I have often referred to it in later models. Small as it seems, the turret housed two PF Medium motors and a single linear actuator. Both motors had safety clutches based on the standard Lego 24-teeth clutch gear, and were powered from the hull by two wires. This resulted in at least 360 degrees of turret’s rotation (I didn’t try to rotate it more, lest wires – and subsequentially the motors – get damaged), which was controlled by one of the motors. The other motor drove the linear actuator which controlled main gun’s elevation. The linear actuator turned out to be perfect for it, blending precision with strength. It was mounted in a fixed position, as a single part, without additional braces that are usually attached to linear actuators, which let it fit inside a 2-studs wide space inside the turret.

The model was decorated with custom stickers, in large part based on the original signs used by the British army. It was my first construction photographed against a professional backdrop. Unfortunately, I’ve decided to use the same background for filming, which turned out to be a very bad idea because of the very high image contrast involved.

The model looked rather well, despite the too tall hull, and its performance was satisfactory. It was somewhat slow, and due to a delicate hull’s structure I was afraid of testing it in any difficult terrain. Some time after I’ve filmed the model, it turned out that the batteries inside it were only half charged, hence the crippled performance. The turret, however, worked perfectly well, thanks to the use of a linear actuator, and a good weight distribution, which let it rotate very smoothly. It is possible that the model could look and perform better if built in a slightly larger scale, but still, it was a milestone in the development of my tank models.

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Remote controlled gun, in two versions. Both feature full rotation and a sophisticated positioning system, one features rotated barrel and illuminated fiber optics, and the other features firing mechanism with an ammo clip.

Datasheet:

Completion date: 22/09/2008
Power: electric (Power Functions)
Dimensions:  unknown
Weight: unknown
Suspension:  none
Motors: 5 x PF Medium

The basic idea of this construction was a tripod made of three independently controlled linear actuators. It sounds simple, but was quite challenging, since I wanted to be able to control it by moving only one actuator at a time. It was possible only with three actuators, and only with a very specific geometry of the element that connected their tips. The tripod was set on a Hailfire Droid wheel, that served as a base for the rotation mechanism. On the tripod, there was a simple gun with rotated barrel and the fiber optics element powered by a single motor. When I’ve been building this version, I’ve learnt about the firing mechanism developed by the LUGPol user Duku. With his kind permission, I have installed on the tripod a second version of the gun, that looked completely different, but was able to actually fire projectiles.

Despite its simplicity, the gun was able to fire 12 projectiles over a couple of seconds at a range of up to 3 meters. The ammo clip was moved by the gravity, and ejected from the gun when empty. The whole mechanism has later become a subject of my study, with the intent of using it in some military models.

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Media reference:

The Brothers Brick

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Small tank built to test the compactness of the PF system. Features remote drive and steering, plus turret rotated by a crank, and main cannon elevated by a crank.

Datasheet:

Completion date: 24/05/2008
Power: electric (Power Functions)
Dimensions:  length 38 studs / width 18 studs / height 12 studs
Weight: 0.87 kg
Suspension: none
Motors: 2 x PF Medium

My last fictional tank, not related to any existing vehicle. It was built to serve two basic purposes – to test how tightly the PF elements can be packed inside a construction, and to test how the tracks perform when there are wedge belt wheels used as the drive wheels. To test the first goal, the tank’s silhouette was extremely lowered and flattened. Eventually the tank’s hull is only 3 studs thick, and houses a battery box, an IR receiver, and two motors – something that is probably hard to guess just by looking at the tank. The drivetrain was very simple, with single motor driving each tread. The turret was rotated by a crank at the back of the tank, and its main gun was elevated by a crank at the turret’s back. To support the gun’s weight, a gear on an axle pin with friction was used. While I consider the tank pretty ungly, I also believe it to be a boundary mark between my first generation of tanks, and later, much more sophisticated and accurate models.

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My second model of an actual tank. Features a drivetrain with a subtractor, pendular suspension with possibility to tilt the hull pneumatically, pneumatic front dozer blade, detachable side skirts and rear fuel tanks.

Datasheet:

Completion date: 08/03/2008
Power: electric (Power Functions) / pneumatic (fed from internal electric compressor)
Dimensions: length 58 studs / width 25 studs / height 20 studs
Weight: 2.0 kg
Suspension: pendular bogies
Motors: 1 x PF XL, 2 x PF Medium,
Pneumatics: two circuits with one autovalve and one manual valve

This tank, again, has been inspired by someone else’s work. It was Mrutek’s smaller model that drew my attention to the Swedish Strv 103 tank. The tank is so unusual, that I just had to create a model of it. Since the scale is entirely different, I did not rely on Mrutek’s work, I have just learned of the original tank’s existence from him.

The look of the model is not actually very accurate, it’s slightly too large and out of proportion, and the suspension system looks  entirely different. It maintains, however, the characteristic silhouette, which apparently makes up for it.

The space inside the hull is utilized down to the last stud: rear and middle part of the chassis are occupied by the classic subtractor, used in my several previous tanks. The front part of the chassis houses a horizontal battery box and the entire pneumatic system, that is two circuits, one used to elevate hull on the suspension, and the other one used to control the front dozer blade. The first circuit is controlled by an autovalve I have designed earlier, which allows to use a single motor to drive the compressor and to switch the pneumatic valve. The second circuit is attached directly to the compressor via a manual valve. When the valve is opened, the compressor feeds the second circuit exclusively, without affecting the first one. It is possible thanks to the pressure principle – second circuits needs less pressure to operate, so if the compressor feeds both circuits at once, the second one utilizes all the air provided, thus not letting the pressure to reach the level needed to operate the first circuit.

The chassis, probably the tank’s most noteable feature, is not very complex. On each side of the tank, there are two stringers, one above the other. The upper stringer is entirely attached to the hull, while the lower stringer has only two points of attachment. One of them is a central transverse axle that connects it to the upper stringer. The other one is the top of a pneumatic cylinder which connects it to the front part of  the hull, thus controlling the hull’s tilt. I have, in fact, tried a number of purely mechanical solutions before relying on pneumatics. Given the hull’s weight, however, each mechanical solution turned out to generate a significant backlash, and the linear actuators were not yet available at that time.

I have put a lot of effort in the construction of the chassis, which has been test-driven in a huge variety of conditions. That resulted in a very good off-road performance of the tank, additionally supported by the use of a subtractor. I believe that the weight of 2 kilograms was pretty close to the limit of capability of a single PF XL motor driving the model over multiple obstacles, and if the model was a little heavier, it would have to be fitted with a second PF XL motor – which would result either in much larger size of the model, either in removal of the subtractor to gain space for the second motor.

The response to the model, both local and worldwide, has by far exceeded any of my expectations. Some people, who are familiar with my later work, still consider it my best, or one of my best creations, while in my personal opinion it could be significantly improved. Note that this was the first case of a good quality video, as I have paid little attention to the video materials earlier.

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Media reference:

Brick Blogue, TechnicBRICKs

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My first model ever. Very small, features drive and steering powered by Power Functions.

Datasheet:

Completion date: 17/11/2007
Power: electric (Power Functions)
Dimensions: length 31 studs / width 20 studs / height 9 studs
Weight:  0.62 kg
Suspension: none
Motors: 2 x PF Medium

This is the first time I dared to build a model of an existing vehicle. LUGPol user pepik should be credited for that, as it was his model of Mark I that inspired me to build a functional version. His creation was just slightly larger that the battery box, and that made me wonder if it’s possible to fit some mechanics inside. After much effort, it turned out possible.

The tank is built basically from two treads held together by a horizontally placed battery box. It was quite difficult to design treads so that they could work and has space for the box inside, and any kind of suspension had to be sacrificed along the way. The IR receiver is located in front of the tank, inside the driver’s cab, and two PF Medium motors are mounted behind the box. Each motor drives one tread at a very high speed – there was simply no space for more gear reduction. Some photos show the size comparison between the finished models and the PF elements it contains, as well as the model’s internal structure.

The tank looked well and worked well, which prompted me to try more models on my own in future.

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Media reference:

Klocki

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