The king of the modern battlefield is and has been the main battle tank. These armored vehicles can push the enemy off their held ground through mobile offensive power and are a key element of modern mechanized/combined arms warfare principles. When the modern main battle tank (MBT) engages a target with their main gun that is in 105mm to 120mm range, few things on the face of Earth can survive a direct hit by the shell of an MBT. However, the main battle tank that has existed since World War One, days could be numbered. Smaller, more portable armored vehicles that are also modular are on the VR drawing boards. But, could the daring of the military sci-fi genre, mecha, be the ultimate replacement for the MBT? And which one is better? Much thanks to FWS reader Matthew Kreis for his question!
The Mech vs. Tank Argument from the POV of Military SF
What FWS is Considering an "Mech"
What FWS is Considering an "Tank"
A Word on Superiority of Mechs and Tanks
A Word on the Technology of Mechs and Tanks
Which One is Better for Land Combat? The Face-Off between Mech and the Tank!
Mobility on the Battlefield
However, if the mech ran to dense forest to escape the charge of tanks, the mecha could then have the advantage, due to the woods stopping the tanks if dense enough. Mecha could be deployed in regions that tanks cannot go, like jungles, swamps, and even dense urban environments. However, there is much debate on this. It should be noted that tanks could venture into most built-up areas without much issue if the roads were clear enough. Another element of any navigate of difficult terrain is ground clearance. Tanks can and do off-road well to a point. The US M1 Abrams MBT as a ground clearance of about 1 foot 7 inches or .48 meters and modern battle tanks use their powerful engines, ground clearance, and lower ground pressure to prevent getting stuck in the mud…but, it still happens. Some have cited that the mechs massive weight and all of that weight being on the giant feet would cause issues with maneuvering and overcoming the natural and man-made environment. Mechs maybe just too heavy to traverse swamps and deserts.Then there is the matter of off-world exo-environments.
WINNER: THE TANK!
At its heart, the tank is a mobile gun platform that is constructed around the main cannon. That cannon, which fires shells from anywhere from 105mm-125mm, has extreme destructive capability up to 2,000 meters. That is its primary offensive capability and it is fearsome. Most other modern battle tanks also mount secondary armaments to deal with other threats, like infantry and low-flying aircraft. These are mostly in the 12mm to 7mm range and mounted in various positions, so that crews can access them quickly. Some, like on the Russian T-14 Armata, are remote-controlled. Much rarer are tanks that carry smaller-caliber mortars (like the IDF Merkava) and grenade launchers. One variant of the T-14 Armata may mount 30mm cannons to deal with air threats.
The reason that we are discussing this is because sci-fi has given the combat mech all manner of weapon systems and often mounting several major weapon systems on the same mech. According the old FASA "Battledroids" ads in comic books of the early 1980's (which I remember), one Warhammer heavy mech was equal to 20 tanks. That was due to mecha, like the Inner Sphere Warhammer, being equipped with large particle projector cannons, short-range missiles, small & large laser cannons, and even anti-infantry machine guns. That is a great amount of firepower contained in one single ground combat vehicle.
While most of us pay attention to the sexy weapons of mechs and tanks, there is another side of the equation: defensive capabilities. How do mechs and tanks handle incoming? One of the elements have to keep in mind, is that modern battletanks normally operate within a combined arms strategy, where some of the weakness of the tank are minimized due to tactical air support, infantry, and real-time intel gathering tools, like UAVs. While tanks and mecha and do operate on their own, it is better for their survival if they do not. However, what individually can these heavily armored and armed war machines do to protect themselves? The most obvious is the armor of the tank and the mech. This non-active defensive capability is able to protect from incoming munitions of various types with various levels of damage. An modern battletank, like the M1 Abrams can and do survive direct impacts from other tank shells and even some anti-tank missiles. However, that is not always true, and a MBT are knocked out by infantry-fired AT missiles, other tank shells, IEDs, and aircraft. Mechs are projected to do the same, survive via their armor, which allows them to maintain combat operations even after some hits. Much like tanks, the Mech has to deal with anti-mech missiles fired from aircraft, vehicles, and infantry along with dealing with their own kind. Mechs and tanks also can use speed, camouflage, and cover to protect themselves from their enemies. In addition, mech and tanks can use real-time intelligence from their own sensors, scouts, or UAVs, to avoid incoming enemies.
Then that brings us to active defense capabilities. Today, there are methods to intercept incoming fire and take its fangs out before it bits. These active protection systems are broken up into soft-kill and hard-kills systems. Soft-kill systems are decoys, IR flares, and jamming. Hard-kill systems are more interception based devices like the Israeli TROPHY and the American IRON CURTAIN, and even reactive armor plates to defeat HEAT warheads. Naval vessels have the hard-kill systems like the CIWS that uses rotary cannons and lasers to intercept and neutralize incoming threats. While the modern day MBTs have these soft and hard kill systems, most mecha seen in sci-fi is mostly based on soft-kill, energy shielding, and armor protection.
When we compare the two defensive capabilities both share, armor, we can compare the mech and the tank. If we examine the US military M1A2 Abrams MBT, it weights in at around 70 tons when fully combat loaded with crew, shells, and fully fueled. Half of the weight of the $4.5 million M1 Abrams MBT is the armor itself. The challenge of armor is too much, and the armored vehicle is too slow and sucks fuel, but too little armor, it is a paper tiger that cannot survive the rigors of modern warfare. This would be the same for a mech, but with a whole host of issues not found with a tank. How a human-shaped mech would be armored would be a delicate balance of protection and mobility. Too much armor on the legs or arms, the mech could move or raise its weapon. Too light armor, and vital systems could be exposed to incoming threats.
WINNER: the TANK!
As another military science fiction website expertly summed about surviving combat, it is all about NOT getting hit. Seems simple, but of course it is not. This is especially true when it comes to the tank and it will be true of any mecha developed in the real world. During the Cold War, when the scenario was envisioned that NATO and the Warsaw Pact would be facing off in Europe and the main battle tank would be one of the critical elements of the proposed World War III land war scenario. This meant that a great deal of money, imagination, and time was invested in developing weapon systems that could take out the almighty MBT. It seemed that there was no end to the weapon systems there were developed to take out tanks.
One of the elements that would could against the mech would be its size. Mecha could not hide as easily as the tank, and it would tower over most cover, making it much easier to identify and get ordnance on-target. Depending on the defensive capabilities of the mech, would largely determined of the mech survives to fight another day. While sci-fi likes to say otherwise, there would be anti-mech weapon systems (like the anti-tank TOW missile) developed and fielded for infantry units to take down the metal giants. That means that one determined infantryman with the right weapon could bring down a mech.
Logistical Support and Consumption
WINNER: the TANK!
When we move off-world and the need arises for protection of those interstellar resources/locations, there will be some sort of armored vehicle that serves the role of a mobile gun platform. That could be a mech, or an "tank" like vehicle, or even some sort of armored power suit. The real challenge with mechs and tanks was mentioned above: starlift capability. Getting the mechs and tanks from Point A to Point B in a interstellar battlespace will be a massive logistical challenge that could prevent the constructing of such weapon systems. Instead, we could see the development of different types of aero-vehicles, robots, and APS platforms to take those tasks over and allow for effectively using the starlift capability in place rather than taxing it.