[WIP] Sci-fi tank

[Ctan]

Hi, it's my first seriously started MOC. Very complicated but I think I'll learn a lot doing project like this. Tank is inspired by Starcraft 2 Siege Tank. It's not a copy or scale model. I like fantasy and sci-fi so why not to try.

Here is a demonstration how it should work

Not everything will be copied from this, I have limited space and don't want to create monster.

List of stuff to do:

• Legs/tracks can be moved in two dimensions to create X shape using large LA. [Almost done]
• Each track drive via built in L motor, typical 2 track tank steering [Done]
• Track tension pulley wheel [Done]
• Outriggers synchronised with legs
• Turret 360 rotation
• Turret opening and extending barrels [Removed, not enough space to implement]
• Shooting mechainsm x2, shooting with 3L liftarms [Done]
• Working fake engine with fans [Done]
• Large turntable for turret, bearing from 42082 [Done]
• Openable panel hatches on legs/tracks
• Openable engine cover
• Openable panels on turret sides with additional cannons [Done]

Here are a couple of pictures of progress. Everything now is generally a sketch, lot of things need to be reinforced. XL motor is just for testing small LA work.

Here is a fake engine. Cooling fans are working using trick with 4L hose.

Turntable with same bearing as in 42082 crane.

Here is an leg construction (not present) but general idea is the same.

Here with removable panel. Unfortunately panels need to be rebuild to fit newer shape.

And here is estimated size.

Please keep in mind that this is very early stage of project and it's my first more serious creation. I'm back to Technic after 20 years (30yo new afol) so I need to adapt to new studless style of building.

I've bought my first present set about half year ago so I have to learn a bit now :) Hope this project will help with it.

Let me know what you think!

Edited July 29, 2018 by Ctan
to do list update

[M_longer]

It is doable:

 

[mortenm]

Wow - nice project.

Looking forward to next update!

[Maaboo the Witch]

This looks really good! I like your idea and the basic structure using the track units and outriggers is great. Looks like one to watch, no doubt. 

[Ctan]

1 minute ago, M_longer said:

It is doable:

I know, but I don't want to use pneumatics. Only gears and LA. Pneumatics is much easier way but I don't like it.

[HorcikDesigns]

Looks interesting, I look forward to see it grow.
Where does the DBG 5×7 liftarm frame, seen under the banana gears on first photo, come from? 

[Ctan]

Just now, HorcikDesigns said:

Looks interesting, I look forward to see it grow.
Where does the DBG 5×7 liftarm frame, seen under the banana gears on first photo, come from? 

It came from far East - Aliexpress. I decieded to build tank in DBG and didn't wanted to mix LBG or black frames in project. It was only reason to buy this frames. I hope that Lego will release it someday in this color.

[gate]

Wow, you should really keep going. Interesting to see the final result!

[KD123]

Very ambitious subject, I'm really looking forward seeing this progress.  Have fun!

@M_longer  is that Drakmin's Siege tank from some years ago?  

 

[Ctan]

A small update. Outriggers will be double for thicker look. I've build a sketch of turret barrels and its case to estimate how much space I have for shooting mechanism. Later I'll design it in cad.

Double outrigger

Barrels

Here will be simple worm gear meachnism to pull out the barrels.

Bottom view - barrels are mounted on 1x13 racks. There will be also somewhere large LA for lifting this whole thing. (Blue 3L pins are temporary stops for racks.)

And a quick picture of all mess on my desk :)

Now I have to wait for all bricklink orders to continue sketching...

Edited July 20, 2018 by Ctan

[pagicence]

17 hours ago, Ctan said:

...and don't want to create monster.

Haha, it's already a monster! I'm really keen to see it as much as the dog. I will follow this closely 'cuz I'm kind of building a (semi) transformer myself right now.

[Ctan]

@pagicence : yeah.. It's size is out of control now... Lot of stuff I want to implement made it grow :)

 

I'm working on shooting mechanism but shooting mechanism without ammo is useless.

I've done clip for 5x 3L liftarm ammo. It can be easily filled and replaced. Smallest as possible. It can't be reinforced horizontally but It won't be stressed too much.

Edited July 20, 2018 by Ctan

[pagicence]

Try this mortar shells, with 58176 part for the grain. They are 3L long. I used them in my DS Howitzer.

 

Edited July 20, 2018 by pagicence

[Ctan]

1 hour ago, pagicence said:

Try this mortar shells, with 58176 part for the grain. They are 3L long. I used them in my DS Howitzer.

it's looking pretty cool but it won't work in my gun because it's actually 2L of soid brick for me (shooting trigger is an 5,5 axle)

Here is how it work. Dog wasn't injured during filming ;)

 

[pagicence]

I think it would be cooler if you make it shoot faster. I see that you are using worm gear and 24t gear wheel. Here is my idea: try with 8t instead of 24t (it will shoot 3x faster), or maybe instead of worm gear and 24t try using bevel gears (I don't know how much torque you'll have then to cock the shock absorber).

Edited July 20, 2018 by pagicence

[Ctan]

29 minutes ago, pagicence said:

I think it would be cooler if you make it shoot faster. I see that you are using worm gear and 24t gear wheel. Here is my idea: try with 8t instead of 24t (it will shoot 3x faster), or maybe instead of worm gear and 24t try using bevel gears (I don't know how much torque you'll have then to cock the shock absorber).

Torque can a problem I think, previously it was done with 8t gear but it shoot too fast and I slowed it down intentionally. It will have only 10 shoots so it don't have to be speed demon :) In a very limited turret space  I want to put 4 extra hard springs (2 per barrel shooting one by one) to extend shooting range. So 1 L engine need to handle 2 worm gears and 4 springs. It's now only a speculation  but I think it will be necessary for additional gearing down.

[Ctan]

First tests of lifting mechanism, outrigger will be slowed down for sure to match LA speed and lifting height. It also need limiters of lifting but it will be added for sure.

Here are a couple of pictures what I have now.

Westie for scale :)

Also I'm working on double spring shooting mechanism - especially on Its size to fit in turret. Red pin is a part of ammo clip.

Edited July 23, 2018 by Ctan

[mortil]

Nice. This will be fun to follow as i tried to build a fan-build of the Siege tank but in much smaller scale :P 

[Ctan]

57 minutes ago, mortil said:

Nice. This will be fun to follow as i tried to build a fan-build of the Siege tank but in much smaller scale :P 

I saw your tank, pretty cool stuff! If you build it in bigger scale you'll have more space for more functions :)  Firstly I didn't think that it will grow to this unexpected size...

I decieded to leave barrels extension function because it will be too complicated and turret can't be bigger as is now. Also in turret will be no motors and battery, all power will came from the hull.
Ammo clips also will be changed to gravity feed because of rubber band problem (it generate too much friction on first two shoots). Small one is too short, bigger one is too long to work properly. Best option could be conveyor belt but there is no space for such complex creation.

So barrel elevation and shooting will go trough 2 shafts in turntable.

I've counted motors I need to put there

4x L tracks
1x M barrel elevation
1x M turret rotation
1x M fake engine
1x L shooting
1x XL outriggers and legs elevation
 

and rest of stuff

2x LiPo battery
2x Sbrick

 

[mortil]

Im working on a grenade launcher tank that can shoot.  the whole mechanism will be able to tilt down in to the big turntable.  got most of the turntable done with firing and stuff. 

it was a bit problematic to get it to fit :P 

[Ctan]

On 7/24/2018 at 11:43 PM, mortil said:

Im working on a grenade launcher tank that can shoot.  the whole mechanism will be able to tilt down in to the big turntable.  got most of the turntable done with firing and stuff. 

it was a bit problematic to get it to fit :P 

Yes... MOCs are problematic on almost every step   But it's very rewarding when you solve all the problems and all stuff work as you like!

Here I've got finished shooting mechanism and front part of turret. Finally done after a couple of rebuilds. Working as I like. Now it will be a challenge to fit it on turntable. Openable hatch is for my son, he love to see what's inside :)

(Something went wrong with the picture)

View from the bottom. Firstly mounting point was in the middle but it generate lot of problems and I moved it on the back finally.

 

Edited July 27, 2018 by Ctan

[Ctan]

Almost finished turret, it need a couple of things to do but everything is working. Dog is for scale.
I add two "Technic Competition Cannons" under openable left and right wings of rear turret. They will be openable by manual knob and shooting will be triggered by a buttons.
Now I have to redesign tracks and partial body to fit turret scale... But all main mechanisms are working so it's matter of time now to complete this huge tank.

[Ctan]

Update

After some time I have to start from the beginning. Previous take was not bad but too large and hard to reinforce to be stiff enough. With gathered knowlege from fail I start building main body with all necessary stuff. It's not physically built yet but very soon I'll know where it need to be reinforced. Boogies will be smaller because drive motors were moved to main body.

 

Red axles - forward / backward
Yellow axle - left / right
Blue - turret function
Green - turret function
White - turret rotation

Tracks will be extending using pneumatics and autovalve probably because it will be single function. Large LA's will bring too many problems (especially size expansion) so I left with pneumatics.

[pagicence]

Is it going to be just a little smaller, or significantly? I was really looking forward to see a huge technic model. I'm guessing you will keep the turret. I really like the solution for the subtractor unit, it's packed tight.

[Ctan]

On 8/18/2018 at 2:06 PM, pagicence said:

Is it going to be just a little smaller, or significantly? I was really looking forward to see a huge technic model. I'm guessing you will keep the turret. I really like the solution for the subtractor unit, it's packed tight.

Thank you!

Yes, it will be a bit smaller... but still huge.  Hull is comparable to 42082 chassis. Length is 45 studs and width is 30 studs.

Currently it's very tight packed and also very durable. I like how it evolved. Only thing can be improved now is bracing of turret rotation gears.

 I have dissasembled back part of the turret because it was only an empty shell. Shooting mechanism will remain the same.

Next task is to design and fit new tracks carts. I hope to have more time next months to make it live. 

View from the top:

Bottom:

Red cylinder is substitute of airtank for compressor  (inside is an custom made air container). I plan to use 4 large pneumatic cylinders so it may be useful. 

With turret:

And control unit

If you have any suggestions just let me know :)