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Churchill tank

March 29th, 2015 Leave a comment Go to comments

Small-scale model of the Churchill tank. Features 4 remote-controlled functions and suspension.


Completion date: 29/03/2015
Power: electric (Power Functions)
Dimensions: length 40 studs / width 19 studs / height 14 studs (not including the antennas)
Weight: 1.184 kg
Suspension: torsion bars held by rubber axle joiners
Propulsion: 2 x PF M motor geared 2:1
Motors: 4 x PF M motor

I wanted to build a model of the Churchill tank for a while – not only it is one of the more distinctive WW2 tanks, but it also promised to offer a challenge with suspension system.

One thing that the original Churchill tank proves is that the Brits didn’t quite catch up with this whole “modern tanks” stuff well until late into the war. For many years British tanks were built specifically based on WW1 experiences (one of initial ideas for Churchill was to have no turret but side sponsons instead) and according to categories that nobody heard about but Brits, such as cruise tanks, infantry tanks and so on (Churchill itself was classified as a “breakthrough tank”). In many ways Churchill was 20 years behind when it was first introduced – it was poorly armed, with disastrously shaped armor, sluggish and not so far from Mark I tank in its concept. Its distinctive all-around tracks were completely exposed at first, which would make it a well armored tank in a world where artillery doesn’t exist. Its main advantage was that it wasn’t as dramatically obsolete as the infamously ridiculous TOG II.

When introduced, the Churchill tanks performed poorly and were outclassed in pretty much every possible aspect by German tanks. Winston Churchill allegedly said that the tank “is more flawed than I am” after inspecting it. As many as 1000 out of 1200 Churchill tanks required complete overhaul due to malfunctioning drivetrains – yet lacking any other vehicle that could be immediately adapted to the much-needed role of a heavy tank, the British continued to feverishly improve and develop the Churchill. After a long series of disappointments both on the battlefield and beyond it, the Churchill was about to be scrapped when the African campaign made it unexpectedly shine. The British, being hard-pressed by Germans and throwing anything they could at them, suddenly discovered that the Churchill, the long and slow tank designed to plow through trenches, can get basically anywhere. This was a serious asset in desert conditions which severely limited mobility of most tanks, and the Churchill has quickly gained reputation of the tank that “wouldn’t get there fast, but would get there no matter what”. In fact, the German high command routinely ignored part of the reports about Churchills being spotted in certain areas, simply refusing to believe that any tank could operate there. All in all, Churchill was a “late bloomer” tank and remained in service all the way until 1952, having been used by 5 various countries, including Soviet Union and Poland.

My goal with the model was to make it reasonably small and fully remote-controlled while using standard PF elements only, that is no Micromotors and no 8878 battery. I also wanted it to have suspension, unlike my even smaller King Tiger tank. The finished model was rather simple, with two PF M motors driving left and right tracks separately through the rear sprocket with 2:1 gear reduction. Third PF M motor was located at the back of the hull and rotated a small Technic turntable that connected turret to the hull, while fourth PF M motor was sitting below the turret, driving a small linear actuator that went through the turntable. The actuator was the only reasonable way to fit a gun elevation mechanism inside a turret this low, and at the same time it allowed to rotate the turret infinitely because there were no wires that could be twisted by rotation. Finally, there was a battery box in front of the turret, located crosswise, and accessed by opening top/front part of the hull and opening a door in the side skirt.

The suspension system, which was the most challenging part, needed to be extremely soft and responsive, because not only the model at this scale was bound to weigh little, but being the Churchill it also came with 11 double road wheels inside each track. That meant very little weight per single road wheel. Shock absorbers were too big to be used in this model and standard torsion bars used in my earlier tanks were too rigid for such low weight. The solution I came up with was using modified torsion bars that weren’t locked directly to the chassis, but to rubber axle joiners which then in turn were connected to the chassis and sandwiched between two plates, one above and one below. With this solution, the actual bar – that is axle, which was too rigid to twist – didn’t act as the flexible element: the rubber axle joiner did. This resulted in an extremely soft suspension – one, in fact, that would be too soft for most models, but Churchill’s  many road wheels ensured limited load per wheel. Thus each pair of road wheels was suspended independently, with separate torsion bars for wheels inside the left and right track. The downside was severely limited ground clearance.

As for the model’s appearance, I did my best to base it on Mk IV, the first Churchill that entered serial production. I’m not sure I have succeeded – the problem is historical documentation. With all versions and subversions there were as many as 17 official variants of the Churchill, and that does not include tanks that were being upgraded, adapted or experimented with. To make things worse, most historical photos show not stock tanks but machines that have been in service for a while, having been damaged, repaired, patched up and so on – not to mention that some Churchill’s variants were called different numbers depending on where they were deployed.

I think the looks of the models were reasonably good, but not perfect. The side skirts were a little bit too thick (although not as much as may seem), the front part of turret’s top wasn’t sloped, turret’s rear wall was a bit too wide, and the main gun’s barrel was slightly too thin and to narrow (by less than 10% according to scale). My only alternative was to make the barrel way too thick, so I considered this acceptable. Finally, the extra fuel tank at the back was separated in the middle while it should have been whole.

I was quite satisfied with this model as it has met my goals, especially the two most challenging ones: using a standard batter box and creating an effective suspension system. Due to the length of its tracks and limited torque of the PF M motors it could only steer on the floor, but other than that if performed really well, especially for a small model. Its appearance seemed a bit dull to me, but the original tanks were kind of dull in appearance and didn’t have any official larger markings on them that could make for interesting stickers.

Work in progress photos:

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  1. Sariel
    September 26th, 2016 at 23:04 | #1

    @Nate Lee
    There are no instructions, that’s probably why you can’t find them.

  2. Nate Lee
    September 26th, 2016 at 19:05 | #2

    Is there instructions for this?
    I was wanting to build it. But I cant find any instructions anywhere that I look.
    If there is any instructions for this that you have and can provide I’d be very happy.

    -Nate Lee

  3. Sariel
    October 31st, 2015 at 22:04 | #3

    Thanks but no.

  4. MGH
    October 31st, 2015 at 18:35 | #4

    An amazing build, well done.

    Are/have you published an instruction set for this model?

  5. Sariel
    July 19th, 2015 at 19:31 | #5

    @Gian Luis
    Cool, but I don’t want to.

  6. Gian Luis
    July 19th, 2015 at 15:40 | #6

    You can build churchill gun carier you just need to modify this one.

  7. Sariel
    July 19th, 2015 at 15:12 | #7
  8. Gian Luis
    July 19th, 2015 at 04:18 | #8

    I can suggest something?

  9. Sariel
    July 18th, 2015 at 23:34 | #9

    @Gian Luis
    I don’t know how I can help you.

  10. Gian Luis
    July 18th, 2015 at 22:54 | #10

    I want to build a churchill gc but i don’t know how to do the front and what plate you put in the back. The size is like this one.

  11. Sariel
    March 30th, 2015 at 20:21 | #11

    You mean “this small and this light”? It’s hardly a challenge.

  12. March 30th, 2015 at 19:06 | #12

    Wow! Do the M-motors have any difficulty driving something this size and weight?

  13. Ev3fan
    March 30th, 2015 at 11:48 | #13

    Oh yes, the first churchill is very bad, also in WoT. When I got it I was really excited about my first heavy tank with awesome armor, but is’s just an alp-dream to play. I hope Churchill IV plays better. Your model is awesome and looks reallly accurate. I’m dreaming about a whole series of famous WWII Tanks all in the same scale which woud fight each other in a LEGO environment.

  14. Sariel
    March 30th, 2015 at 03:42 | #14

    Yes, the barrel raises very slowly and when it reaches extreme position, the clutch in the LA clicks and the turret keeps rotating. So yes, it can rotate infinitely.

  15. March 30th, 2015 at 03:18 | #15

    Nice compact tank.
    Can the turret rotate infinitely, or does the barrel slowly raise itself as the turret rotates?
    eg. What happens if the turret rotates in one direction 19 times?
    If the barrel is all the way up or down, what happens when you try to rotate the turret further? Does the mLA’s clutch start to click?

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