sonar

My advice would be to roughly build whole tank without motors for the propulsion. Then according to the weight of the model you add either 2, 4 or more XL motors. At minimum you should use XL motors (NTX, EV3 or RC buggy are better). Neither Large nor Medium motor is powerful enough to move tanks around reasonably fast. By fast I mean faster than big construction models you see in this forum. Tanks ar not construction equipment. They must go fast!

The width of any tank is determined by the turret ring in my opinion. If you examine real tanks you could see from the moment the Main Battle Tank concept was developed, every tank uses the hull as wide as the turret ring allows. This is always a balancing act from tank development perspective: the breech of the main gun increases the size of the turret ring the higher caliber of the gun goes, the smallest frontal profile is desired which is achieved by decreasing the turret ring. If you plan on adding turret with mechanisms inside it, I would suggest taking into account the space between tracks these mechanisms will take when turning the turret. I'd suggest examining Kelkschiz Mark 6 Autoloader Tank to see the modern real life tank development concepts applied using Lego.

Thank you for your updates on the research. That is an excellent solution!

My thoughts exactly. The combination of wheel hub and sprocket into one part is a very very good idea.

Another excellent video! Also these window seals can be found made of different materials and the grip between surface and tracks could be adjusted accordingly. Might I suggest increasing weight of the model and testing the performance. Right now these are just bare bones of any tracked vehicle. In my experience even dual XL motors struggle on the finished model when I add body and other mechanisms (pneumatics, compressors and what not) to the similarly sized vehicle. Adding another kilogram could change performance drastically I think.

From my experience you need to decrease traction between ground and tracks for tracked vehicles. Increased traction eats away too much motor power to the point where the vehicle even struggles to make a turn. This kills off ability for a model to turn around on it's own axis ( ) assuming the model is in the 3-5 kg weight class.Either way I prefer performance on even terrain over steep climbing abilities like demonstrated in the video above. Few thoughts from my point of view.

I had success removing sticker glue with WD-40. I was cleaning glass jars though. Not sure if WD-40 is harmful to plastics. Spray the lubricant on a paper towel, press it against the area with glue and let the glue soak it in from the towel. After couple seconds wipe it all off with the towel. Obviously the part needs to be washed with soap to remove the lubricant.

Thanks for the update. The Mark 6 is very innovative in Lego tank design in my opinion. Looking forward to your next creation.

Hello, Kelkschiz. How's progress on Mark 7 Autoloader tank (if you are still upgrading Mark 6 version)?

The video composition and camera shots are very good!

Awesome MOC. The tracks look very cool. I wonder, what part is used as a sprocket? The track would slip without a sprocket I believe.

Reminds me of the Machine from one of my most beloved sci-fi movies - Contact. Please post a video of this mechanical sculpture if you can. Would like to see it in action. Edit: just got an idea. Maybe it helps you. You could simplify the contraption by using rectangular frames instead of circular frames. It should work the same.

How about putting them in hot vinegar for couple of minutes? The chemical cleaning should be safer instead of mechanical abrasive cleaning like sanding and polishing. It works for cleaning pennies if I recall correctly.

Yes the leaf spring suspension is different because unsprung suspension elements mount directly onto the leaf spring. This system is different. The rest work on the same basic principle: coil spring element on one end of the swing arm and roadwheel on the other end. One coil spring + one swing arm - basic trailing arm suspension. Combine bogie suspension with two trailing arm suspensions - you have VVSS suspension. Change direction of the coil spring - you have Christie suspension. Mount two Christie suspensions back to back - Horstmann suspension. Replace coil spring of trailing arm suspension with torsion bar - you have torsion bar suspension. All of these work on the same principle.

Well these cylinders look big enough to fit only in the biggest models. Besides any use of spring elements is by definition a Christie suspension. What I am thinking as Hudropneumatic suspension is all pneumatic cylinders for every roadwheel connected into one closed pneumatic system. But I guess it is not so easy to pull off.

I was thinking the same thing about Lego pneumatics. The system uses air which should be compressible. Therefore the lower the pressure, the softer the suspension. Can you sustain different levels of air pressure in the system? Or does it work only in binary mode (full pressure-no pressure) and does not have in-between states (Sariel's book does not explain that)? I do not own any pneumatic elements and have no experience with them.

Thanks for the video. But you could have mentioned the most modern - the hydropneumatic - tank suspension which is used by most modern tanks: K2, Type 10, Altay, Arjun, Challenger 2 or Leclerc. Has anyone tried to replicate this type of suspension on tracked Lego vehicles?

Ah finally complete wheels chart with rim and tire diameters. That will be useful. Thank you.

I am using rechargeable batteries (accumulators?) that each supply about 1,2 - 1,3 V. That's why I get the odd 2,6 V voltage instead of 3 - 3,2 V if I used alkaline batteries. Now that I think of it I will use LEDs without any resistors since the current is 30 times lower than maximum allowed. Which is even better because the whole assembly without resistor is smaller, easier to make and can fit every tiny corner on a Lego model.

I'm building custom LED lighting too. I need a little help. Should I add resistors anyway if my LED is rated at If = 30 mA, Uf = 3,3 V, but the actual current it uses is about 1,7 mA when connected directly to two AA accumulators in series (voltage 2,6 V)? Would resistor give some additional protection or is it unnecessary in this case?

So you are telling that the smooth connector 59443 (yellow) you use prevents the clutch ring from slipping out from the clutch gear under high torque? And the ribbed (flanged) connector 6538 (blue) slips out easily? That could be very useful.

The clutch ring not slipping out under high torque (potential energy of rubber bands)? Seems unreal as it always slips out for me. Must be robust build in here that prevents this situation.

Another battery box mod without actually destroying battery box so much. Also quite aestheticaly pleasing. Just use battery box without the lid where the additional cables stick out.

Any candidates for a sprocket job? Maybe this guy (Expert Builder gear g21)?

The round parts (road wheels) give a nice authentic design. I like it very much! I would suggest avoiding red selector rings in transmission directly after XL motor. They have problems in keeping a locked position and can slip out at high torque (for example climbing an obstacle with such heavy tank). Should we decrease torque and increase rpm when dealing with red clutch rings?