How could very large (but not that large vehicles) be used in combat?

Question

There are many questions & answers on Worldbuilding Stack Exchange about extremely large vehicles weighing 1000+ tonnes. But not any I can find about still very large but not that big vehicles ranging from 80-200 (metric) tonnes. Still bigger than most real world combat vehicles; but vehicles of the size have been made. Such as mining trucks, heavy mining excavators, the Maus, Karl-Gerät, T95 Gun Motor Carriage, Tortoise heavy assault tank, T30 Heavy Tank, TOG2, K-Wagen, E-100 & E-75, although none have ever entered production outside of the extremely limited run of the Karl-Gerät.

My question is: How viable could a armoured fighting vehicle of this size be on the modern battlefield? How much crew it could have and what it could be used for? (Keep in mind it wouldn't be an 8kph Maus level of speed, if an 416 ton mining truck can go 55kph, a tank that is designed with speed and a smaller profile and weight can go faster.)

BTW, please refrain from "tanks are obsolete because drones" comments that go around everywhere. People have been saying that tanks are obsolete since WW1 and they have been proven wrong many times over.

Answer 1

Hit first

These days tanks have incredibly advanced armour and defensive options. Yet there is one main tactic used. "Hit first, so they cannot fire at you." The reason for this is very simple. Firepower is so big these days, that most hits are a guaranteed bad time.

Big vehicles can leverage this. Their armour might be able to be thicker, as well as their defensive arsenal of misdirection. However, their offensive capabilities and detection systems are where it's at. They can have bigger, further ranging weapons than their smaller counterparts. Together with their superior detection, or via the detection capabilities of another unit in the field, they can pinpoint and calculate the trajectory of a long distance shot. Then they can destroy the enemy before it gets in range. They can have a huge supplementary (or main) arsenal of rockets, autocanons and huge rapid fire guns. This allows further staying power against any air or ground assault, as well as some defensive capabilities against flying armaments.

They might not go in the front line, but their support capabilities will be impressive.

The big problems

Being big comes with a host of problems though. Like the mause in your example, it is very bad for the ground. Roads get damaged, it can easily sink in softer ground, the wheels/tracks/other that drive it forwards need to be of special matetials and can still wear quickly. This immediately presents a vulnerability. It's movement is restricted by bridges their size and weight capabilities, the width of roads, whether or not you want to damage/destroy roads by just driving on them, soft ground, forests and more.

It also presents an easy target. Despite a huge arsenal of anti detection measures and a whole lot of camouflage, it's still big. It can be detected relatively easily. If it goes through a forest the trees are likely not much if a problem, but you can also follow the behemoth easily from the destruction of just driving. That will attract an airstrike or heavy weapon fire rather quickly.

It also represents a large cost. The components, weapons and even just maintenance, not to mention fuel cost, will skyrocket. This is even without it getting fired upon.

The fact is that a small devision of specialised vehicles likely offers more firepower, mobility and stealth than one behemoth. As well as a distributed intelligence gathering, the one big tank is unlikely to add it's worth when added to a battalion compared to several smaller specialised ones.

Conclusion

Strong, capable, far reaching, difficult to take down. Easy target, high costs on all flanks, limited mobility that can destroy even when you don't want that, easily replaced with a host of cheaper, specialised units.

Answer 2

• As a tank:
  Tank designs balance armor, mobility, and firepower. The square-cube-law suggests that getting bigger will improve your armor as the ratio of surface to mass goes down, and that it will decrease your mobility, again as the ratio of surface to mass goes down.
  So find some concept that limits the utility of shaped-charge attacks. Better explosive reactive armor, widespread electromagnetic reactive armor, maybe. While you're at it, limit the effectiveness of smart bombs by laser detectors and sensor jammers. That would increase the value of big, direct-fire guns. Those guns need to go onto a big, armored vehicle.

• As an equipment carrier:
  You might want to transport a big piece of equipment -- a howitzer or mortar, a radar, a mobile hospital -- on a single vehicle, rather than a fleet of vehicles that have to stop and reassemble it. Think of the M1 8" Gun on two transport trailers with the self-propelled T93. So think of something that needs to travel as one unit and put it onto a large all-terrain platform. Not a frontline combat vehicle.

Answer 3

Your idea seems to have the same issues as the other "big bad thing" ideas: in a combat scenario where mobility and velocity are key factors for gaining strategic and tactical advantage, having some big and slow doesn't seem a good move. That's why forts have become obsolete.

Also, hiding/covering a big thing is more difficult than hiding/covering a small thing. And you don't want to be the point of attention of all your enemy artillery, right?

Moreover and once again, making one of those would take away resources from many more smaller machines. And as anybody has probably experienced in a pic-nic, taking rid of a single big attacker is always way more easy than taking rid of a swarm of smaller ones, else ants or bees would not be a bother.

Answer 4

Ultra-heavy vehicles will always suffer in mobility. You need many wheels to carry such a behemoth and the loss of a few would stop it. Tracks might seem the ultimate choice, but the longer you make tracks the more the front and backside of the tracks drag across the ground, tearing the ground or road and slowing the vehicle whenever it wants to turn.

The last solution: legs, 6+ legs. Not the game and movie legs that are more often than not just spikes but legs with well designed feet. The simplest design improvement to feet would be to make them extend towards the center of the chassis, allowing you to get more surface area without making the vehicle broader or shortening the step length of each leg. Wheels and tracks can't have armor skirts that protect them entirely as they need to be able to go up/down slopes and need space to lose any sand, mud and rocks that get caught by the tracks/wheels. The legs can be fully armored, although you probably wouldn't try full 120mm canon protection. Like other 8-wheeler combat vehicles legs have the advantage of being able to lose up to half of it's legs before being disabled, although less if you truly use a 200 ton vehicle. This is still superior to tracks which are disabled the moment one track is busted.

There are reasons to use wheels on combat vehicles because of the advantages they offer, there are reasons to use tracks on combat vehicles for the advantages they offer. There are also advantages to legs. A tank can at best climb the height of it's tracks and wheels half their height, but a legged vehicle can step higher. They can climb steep terrain much better, and that is one of the key places you would use such legged vehicles.

Legs also allow the chassis to absorb more recoil. An example: https://images.app.goo.gl/FqPzcaheCLnkmko99

The scoops at the back of this howitzer have an articulation which extends the time it takes for the recoil to be fully absorbed. This allows a bigger gun to be mounted on your vehicle for the same weight as the legs can collapse and extend the distance at which the vehicle is stopped.

The best way to use your vehicle: moving artillery base, moving AA missile battery with radar systems, steep terrain combat vehicle, vehicular trench warfare (it can poke up rather than drive into and out of a preprepared position) and assaulting across minefields (feet can be more resiliant and discontinuous walking means less chance of detonating mines).

Answer 5

Intimidation and Logistics

Other answers address the combat capabilities of such a beast, so here are two other important considerations. Most of the effort in a battle doesn't go into shooting at the enemy. Logistics are a huge component. A gigantic vehicle could carry a lot of people and supplies. The TC-497 road train was designed to haul 150 tons of supplies across the arctic during the Cold War. The Snow Cruiser (pictured above) weighed 75,000 pounds. If you need to move a lot of stuff, you could do worse than having a gigantic truck.

One other advantage would be projecting force. Aircraft carriers are gigantic vehicles and they are regularly used for asserting control over an area. If you want to send the message that you're powerful and mean business, send the GIGANTOTRUCK.

Answer 6

Most objections against 'big and bad' have been covered, but one more point needs to be considered: During WW1, and even more so during WW2, battleships became more of a liability than an advantage. Not only are they fairly easy to hit, due to their size, they are also prohibitively expensive. to sink a 100.000.000$-ship you only need one torpedo, or half a dozen bombs. Plus, it's very demoralizing to lose one of those things, or quite inspiring to the other side.

with aircraft it was shown in WW2 that many cheap weapon systems have huge advantages over few large and expensive ones.

But since you want to consider ground vehicles: the tiger was massively superior to the sherman. But price and complexity limited its availability. while in a 1-on-1-fight the sherman hardly stood a chance, odds change quickly when it's one-on-many.

So: having one big beast is awe-inspirung, yet expensive. Losing one big beast is very inspiring for the opposition, and financially, the cost of destroying it is nothing compared to it's original price. Spam the enemy with hundreds or thousands of small dispensable drones. each one might be easy to defeat. but all at once might still see enough getting through. And losing a drone costs next to nothing.

Since you don't like drones: spam them with small, light, cheap and agile vehicles and infantry.

Answer 7

Missiles and Automated Systems are incapacitated:

To make this work, you need to create a scenario where the advantages of being big outweigh that of being small. If smaller weapons systems are rendered completely incapable of hitting a sufficiently large target, then bigger is better because small is worthless. In this I'll assume advanced armor systems that reduce the effectiveness of many modern weapons. Something will need to address mines (legal/engineering solutions), because mine fields will seriously reduce the effectiveness of large vehicles.

• EMP: So one approach is to make your battlefield an electromagnetic nightmare. Missiles are knocked from the sky because guidance systems are incapacitated within minutes if not seconds of being launched. Autonomous vehicles can't work because they're fried. The only electronic system that even remotely has a chance is on sitting inside an armored and heavily shielded Faraday cage inside a big vehicle (with multiple redundant systems in case they're fried too). A vehicle switches for seconds to a fire control system that calculates trajectories and then closes its systems off again. Humans being slightly more resistant to all this EMP are needed to keep the vehicles going. Only big kinetic weapons are able to damage the advanced composite armors because smart weapons aren't smart.
• QUICK DRAW: Weapons are another avenue for these vehicles. Advanced laser weapon systems and big vehicle-mounted rail gun systems allow even projectiles to be targeted mid-air and with insane speed. The supremacy of aircraft is seriously questioned, as they are too light to defend, and weapons fired from over the horizon are simply vaporized. A thousand drones are mowed down in seconds by a laser that can retarget as fast as a reflector can redirect the beam. The massive armor of these beasts can resist the fire long enough for their huge slugs of iron to pummel weapon systems capable of resisting the lasers. Zap a giant metal slug, and all you have is a hot, melty slug killing you. The large power requirement for the weapons means no small tank can mount these super-fast super-powered weapons, and only big vehicles can carry the armor to resist them for even a few seconds.
• FORCE FIELDS: Don't be too held up by what's currently possible. An oldy but goody is the development of a forcefield generator. It's a BIG piece of equipment, so good luck hauling it around in some prissy little 50-ton tank. Add the portable nuclear reactor needed to power the thing, and bigger REALLY becomes better as your balance of size-vs.-eggs-in-one-basket shifts to the 80-200 ton range. Your generator vehicle becomes a mothership for more vulnerable drones and small vehicles that cling closely to it and sally forth to attack. The massive weapons needed to break shields mean specialized forcefield-generating forcefield killers take the place of tanks. If these beasts are largely used offensively, then the presence of a nuclear reactor might make folks careful about where they want to try and kill your vehicle, as radiation contamination is a real issue.

Answer 8

Interesting challenge. First, you need a compelling reason to have large vehicles. As covered by others, losing a large vehicle means a lot of lost power and money. Second, you need to make it survive.

First one could be mobile factories that produce smaller craft that will actually do the fighting. Using large vehicles for fighting is unnecessary but factories need space. You can recycle damaged vehicles that are yours or the enemy's to stay in combat longer. Another option could be a mobile defense platform featuring rather large systems similar to iron dome.

Second problem can be mitigated if you have good defensive technology. Anti-missile systems can stop strikes. If cannon fire can be detected rather early, it might be possible to intercept using counter fire.

Answer 9

A land carrier

Existing ultra heavy vehicles are all special cases. There is virtually no practical use for them in modern combat. A heavier tank would be only marginally more robust, while its mobility would suffer dramatically.

SAM batteries can push up the requirements for total system weight, but they are too easily split into several vehicles.

However, we may come up with a concept of a mobile drone base which would necessitate a long length for a single vehicle as well as significant overall weight. This "land carrier" would travel in a "carrier group", accompanied by regular tanks, drone transporters and SAM batteries. When deployed, this "land carrier" would act as a small airbase, suitable for pilotless drones, but too small for human aircraft, and project power over the local area. Its medium-sized drones would fill the gap between larger aircraft launched from distant air carriers at sea or friendly airbases, and small tactical drones that can be launched without a proper landing strip.

See also: Is a land-based aircraft carrier possible?

Answer 10

You might want to look at Road Trains. These are a real thing, and are used for long-range logistical support, weighing up to 150 Tonnes (or is it Tons?). There are some good youtube videos showing how some companies use these as heavy goods movers.

https://www.youtube.com/watch?v=0iFkKRh5kcM

Road trains are more efficient on drivers, and more aerodynamically (fuel) efficient, and can carry a lot of goods. You need a road though.

Answer 11

It has a nuclear power plant

Which is why it is big. The nuclear power plant is the same type as is used on submarines and itself weighs about 100 tons. With nuclear power the tank does not need to refuel and has loads of power. Enough power for its primary weapons to be railguns, including Phalanx-type automated railguns to take down drones, planes and missiles at considerable distance. Using electrical power to throw railgun projectiles saves onboard space because these projectiles are smaller than those which must carry their own propellant.

This heavy tank would not need to refuel for long periods of time which is a huge asset. The main issue as has been pointed out is weight and the tendency of the tank to sink into the ground. This is not a problem because the tank is a hovercraft, using its copious power to drive fans which carry it over any kind of terrain or water. The heaviest hovercrafts now existing are substantially over 200 tons. The hovercraft propulsion also means this tank is fast across all types of terrain and will not be slowed by broken treads or wheels.

The main issue with the tank is heat produced by the reactor. Fortunately the hovercraft aspect does double duty here. Enormous volumes of air are moved by the motive fans and heat is dumped via radiators into this maelstrom.

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I am thinking about this nuclear hovertank. I would attack it with cruise missiles. A tank like this would have associated flying drones to extend its sensory abilities and see missiles coming. Also high flying drones could feed it info about remote targets to enable firing solutions for targets many km away. The drones would be battery powered and would take turns, coming down to recharge. They could be named Huginn and Muninn