The Motorpool: Mechs vs. Tanks

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

Since the very beginning of military science fiction with H.G. Wells' 1898 War of the Worlds, there has been Mecha in the form of those Martian tripod walkers (watch for an Our Enemies on that topic soon!). For most works that frame mecha in the role as the offensive push in land/ground combat that smashes the enemy, takes their ground from them, and then holds it from other armored threats and infantry. The role is already taken by the main battle tank and that's a problem for government accountants. So, which one would future governments pick to fund and deploy? Well, accounting to most creators, it is the almighty metal pilot giant. If the creator has selected the mech as the king of ground combat, than the tank, if seen, are often weaker and easily handled by the mech. It would be interesting to see mechs and tanks on a equal footing duke it out.

What FWS is Considering an "Mech"

First, a little background. Mecha or "meka" is the Japanese term for "mechanical” and is a board generalized term for all manner of vaguely humanoid robotic devices, which encompassed everything from automotive robotic workers, to Honda's Asimo, to the giant robotic war-machines popular in Battletech, Transformers, and ROBOTECH. But when it comes to cataloging Mecha in the wider scope of futuristic war-machines, we can place the concept of"mecha" more in the vain of bipedal or even hexapod piloted war-machines that are much larger than the human crews that control them, think more along the lines of modern main battle tank on legs. Often the word mecha and armored power suit are mixed up and used interchangeable. Mecha is more of vehicle than an armored suit worn over the body of the pilot/controller.  When we examine the mecha of Battletech, Titanfall, and Macross, they are more of a vehicle with the controls being setup similar to a fighter or tanks. When pilots use their own limbs to control the machine, it is more of a CLASS-III APS rather than a traditional mecha...the massive mecha suits of Pacific Rim are a hybrid in someways, but the of those war machines size is far beyond most APS in sci-fi. In addition, there are the Bioroids from Southern Cross. These mecha use symbiotic interfacing that allows the pilots to think and the suit to react. These are a form more of CLASS-III APS rather than traditional mecha. For the purposes of this article, Mecha will be framed within those considerations above and for me, mecha will always be those humanoid war-machines from Gundam, Dynamo Joe, ROBOTECH, and Battletech/Mechwarrior.

What FWS is Considering an "Tank"

The role of a tank is twofold. One is that the tanks are tasked with being hunter-killers of their own in sort of cannibalistic way and with pushing the enemy form their positions. Tanks operates within the modern post-World War I doctrine of mechanized warfare and combined arms. Tanks can deliver a great deal of offensive power and psychological effect to the enemy with considerable defensive capability as well. For the most part, most tanks in history have used continuous track locomotion and are mostly constructed around their main gun with machine guns and automatic grenade launchers as secondary weapons to deal with air and infantry threats.

Muddling the water of what is and what is not a proper tank is the more general armored fighting vehicles like the wheeled Italian B1 Centauro and the wheeled American Stryker AFV M1128 configuration. These are classified as “tank destroyers” and a “mobile gun system” respectfully. These are very similar to tanks but designed to either to hunt down tanks with more speed and mobility than the MBT along with being cheaper. The American M1128 is fitted with 105mm gun that can knock down a tank but is used more for heavy gun support for infantry units. There could be an anti-mech AFV that could be classified as an counter-mech mobile weapons platform. When we take a critical eye at future technology posed by science fiction, the battletank has abandoned conventional locomotion types in favor of technology that allows for hovering, like anti-gravity and air-cushion. 

A Word on Superiority of Mechs and Tanks

There is no doubt that tanks and Mecha are very impressive war machines that drive fear into the hearts of their enemies and loosened bowls. However, they are not gods of war, and can be taken down. Nothing used to piss me off when I was a kid and someone would tell me that something was unable to be destroyed. I remember that when Dinosaurs would shown on 1980's cartoons and they were projected as being able to shrug off missiles, shells, and bullets without a care. I call bullshit on that. No Dinosaur could survive an impact of a 120mm sabot round from a modern MBT gun. It would be chunky dino-salsa.

No tank or mech is immortal and lacking in vulnerability. While both mechs and tanks are and would be fitted with a number of defense capabilities, there is always a weak spot...and those fuzzy thugs on Endor proved that. If there is one engineer working on increasing the effectiveness of armor, there is another engineer working on a weapon system to counter that. While modern battletanks are equipped with some awesome armor and defensive systems like the IDF TROPHY system, there are man-portable anti-tank missile systems that can and do take down tanks and that would be the same for mechs as well.


A Word on the Technology of Mechs and Tanks

Even in the realm of science fiction, there must be grounding to the world setting and its technology. Nothing is worse than something that is too powerful. It destroys the integrate of the story and setting. Its like that kid that suddenly tells you that their spaceship has force fields and your attacks are worthless. When we are comparing mechs and tanks, we must advance them both to a more equal level technological playing field. You cannot compare 31st century battlemechs with 20th century battletanks. If your mecha is able to move with the grace of a ballerina and strike like the thunder god, then the armored fighting vehicles of this reality should be similar in advancements for comparison. One thing to keep in mind that was mentioned to me by my coworker Gene was while some actual research has been conducted on mecha, of a sort, tanks have been around for over a hundred years with continuous improvement learned through battle and advancements of science. So, it could be that mechs would need sometime to play catch-up with the tank technologically and some of that advancement would need to come from actual battlefield experience.


Which One is Better for Land Combat? The Face-Off between Mech and the Tank!

Mobility on the Battlefield

One of the most important elements in warfare is movement around the battlespace and the physical terrain poses challenges and opportunities for both sides involved in the conflict. During World War One, the physical terrain and the barriers constructed by humans caused the invention of mechanized warfare in the form of a tank. In certain terrains and environmental conditions, the modern tank is a beast that rolls hard and fast on their prey…however, dense urban environments, jungles (like Vietnam), forests, elevated terrain, and man-made barriers do prevent the use of heavy armored forces. This has fueled research for robotic mules to ferry supplies and even wounded, and some to postulate the use of bipedal and quadrupedal mecha to overcome the geography that tanks cannot navigate. If we compared a mech and a tank on open ground, it is likely that the tank could be outperform the mech in speed and ability to deliver rounds on target.
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.

There are many that have entered into this debate of mechs verse tanks and have cited this as a core reason for battlemecha being superior. The root of this goes back to the belief that mech being more able to navigate and overcome the alien wilderness than the tank. If we examine the vast exo-geography of the worlds in our solar system, we can see the possibility of use of either mechs or tanks or both in off-world environments. Both mechs and tanks would function on the Martian soil due to the NASA rovers that have proven the viability of wheeled vehicles on the red planet. The same is true of Luna as well, but the low gravity and lack of atmosphere would present challenges and it is highly unlikely that off-world armored vehicles deployed to exo-environments such as Luna would not be like the M1 Abrams.  On worlds like Europa, Titan, and even the larger asteroids, the combat vehicles used in off-world conflicts would be far different and not conforming to the argument here. It is more likely that these extreme alien terrains would see the use of armored space suit more on the along the line of armored power suits than mecha.
WINNER: THE TANK!

Offensive Capabilities
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.

Only attack helicopters and attack jets are similar armed, but only the M2 Bradly has four types of weapons that I know of, with TOW missiles, a 25mm auto-cannon, M240 machine gun, and six 5.56mm M231 firing port weapons. It terms of offensive capability, on the surface, the battlemech has the advantage over the battletank. However, is it realistic that a mech could mount that many weapons? Maybe. There is some research on this and the real limits to mounting massive amounts of weapons is the weight and power. Adding missile pods, lasers, particle cannons will bring the weight up and demands on the power plant up. For many mecha depicted in sci-fi, their robotic hands are designed to handle a rifle-like cannon in the same manner as a normal infantryman would handle his assault rifle. This is seen in AVATAR (I know, the AMP suits are a CLASS-II APS), ROBOTECH/Macross, the Titans, and Gundam; those mechs hold rifles and use them in manner like any other shooter.

The issue with this would be the technological challenge to construction a device to allow the pilot to handle the mech rifle in the same manner as the pilot would if they were using the weapon. It can be done, but it might be simpler to mount the weapon in the arm and be done with it. My best guess is that mech would be able to mount more weapon systems than a standard tank. However, I seriously doubt that a mech could fire a weapon in the same size or offensive power as a tank. The recoil stress and energy would likely overcome the structure and balance of a humanform mech design…maybe a spider tank would be better design for mounting KE cannons in the same offensive power scale as a tank. I could see using Gauss KE weapons technology to bridge that firepower gap between an MBT and a Mech.
WINNER: TIE! 

Defensive Capabilities
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.

However, unlike a tank, the surface area of most common sci-fi mecha designs is much greater and the armor would have to be spread out. There will be more weakness, due to light armor protection, on a mecha than a battletank. There are natural weakness inherent to the design as well. For example, taking a page from my Jeet Kune Do experience, it is easier to kick a target in the legs than the face to disable it. The same is true for the battlemech as well. Any anti-mech weapon system would target the least armored areas, like the legs. If the legs on a mech were damaged, it could collapse and be helpless like those AT-ST walkers on Endor. Plus, a falling mech, would be a massive danger to friendly forces as well.

While tank are immobilized in combat, they still can be used to target and kill the enemy...at great risk to the crew. Given these weakness, we could see anti-mech sniper rifles that are designed to take out the knee joints of a battlemech. While tanks have weakness, those weak points are harder to strike than a 30 foot battlemech looming overhead. The steer size of the mech could prevent it from taking cover, like a tank can, and that means more fire is going to be incoming onto the mech's defenses. Given the design weakness of the mech, bipedia or not, the tank offers better defensive capabilities.

However, there will be advancements of material science that will certainly develop lighter, stronger materials that allow for more protection at less of the cost of weight. These advanced materials could help the mech's case in the defense capabilities. Another element of protection is movement. Modern battletanks can move, in the right conditions, over 40 MPH...but could mechs move at the same pace or even more? That is unknown  and advancements in technology could overcome some of this.
WINNER: the TANK!

Survivability on the Battlefield

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.

From the A-10 Warthog, field artillery, to the M47 Dragon, to the BILL missile, to the Apache attack helicopter and on. All of these were designed to kill the tank and these threats came at the battletank from the ground, the air, and from underground (anti-tank mines). The mech would be the same. If, in this fictional universe, the mech replaced the MBT, than the mech would be attacked from infantry, other mechs, aircraft, artillery, other vehicles, and maybe even threats from space. Much like the modern battle tank, mechs would have to operate in a combined arms approach to increase survivability. However, this is sorely lacking in most works that use mechs as the center of ground-based combat.
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 

Everything on the battlefield needs fuel to do its job. Tanks need gas and shells, infantry need chow, porn, and bullets, guns need lube and bullets; and mechs would need their fuel and ammunition to fight. Let us discuss the logistical and consumption needs of the modern battletank first. It takes about four months to construct the M1A2 Abrams without the field testing prior to delivery to the US Army. Once in the field, the M1 Abrams as about 40-42 main gun shells, 490 gallons in its tank, and four crew members that need food, water, and coffee. Under combat conditions, the M1 Abrams would need 300 gallons of gasoline every 8 hours, and depending on the level of engagement, more shells and bullets. Shockingly, the 1,500 BHP turbine engine in the M1 Abrams as a MPG as 0.6 of a mile per gallon. At the armored division level, 600,000 gallons would be needed per day to keep them moving. This is a massive logistical commitment and challenging during wartime conditions.

What about the mech and its logistical impact? The vast majority of works centered around combat mecha has them powered by fusion power plant. From Gundam, to Battletech, to Titanfall; nuclear power sources seem to be the solution to the demands that a mech would place on a power source. Some have suggested hydrogen or even some nearly magical power source, like Invid Flower of Life from ROBOTECH. Some have suggested using radioisotope thermometric generators, but the battlemech would need a great deal of them and then there is the heat generated by the RTGs. Given the massive scale of the mech, the power source would also have to equally massive to feed the demands of the pilot. In addition to keeping these armored vehicles fueled and equipped with ammunition, is keeping them maintained. Tanks would be less mechanically complex than a mech and given that most mechs would be 20-30 feet tall, with repair facilities of a similar size. This would be an amazing commitment and likely unavailable on barely settled exo-planets.

Another element of the logistics evaluation for mechs vs. tanks is getting these weapon systems from their base to the battlefield. Given that we are discussing the mecha and battletanks in an military science fiction vain, we need to think of logisitics on a interstellar level, and that involves starlift capability. Taking a platoon of mecha or a armored division from their bases in the Sol system to a battlefield on the Groombridge 34 star system (11.62 LYs) or on Lacaille 8760 (12.9 LYs) will involve a massive amount of manpower, energy, and physical space onboard the transport vessel. Armored vehicles of the size of an modern battletank are a challenge to move around here on our planet now, and moving them lightyears would involve large FTL transport vessels and some heavy landing craft to get them to the dirtside. Now, image that task with mechs the size of buildings. Moving 30 battlemechs through space, then getting them down through the gravity well of the target world will be a massive challenge as well. This might mean that mechs are never developed on the scale that sci-fi has projected.    
WINNER: the TANK!

Finally Conclusions

In the final analyse of which is better, mechs or tanks, at the role of the king of ground warfare; i am voting for the main battle tank. From my own research, I believe that the tank is superior in mobility, firepower, and in logistics. I do believe that the mech has certain qualities that make an interesting and compelling platform for military science fiction creators and depending on the technological process in conjunction with the strategics picture of the future, there could be a pathway for mecha development. In the lifespan of the tank, which is over 100 years by this point, it has evolved and altered with the strategic situation of the planet. That being said, there are others in military planning circles that believe the days of the main battle tank that we know of today, are numbered. Flexibly, lighter armored vehicle platforms could take the place of the MBT.
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.