A tank designed for urban terrain would have radically different design requirements than a main battle tank designed for open warfare:
Main battle tanks rely primarily upon their speed and long-range firepower and are willing to sacrifice extra armor to retain mobility. In urban combat, however, the reverse is true: fights are at much closer ranges, mobility is measured by the ability to navigate sharp turns and tight/narrow streets, and speed can be sacrificed to retain maximum armor protection. Other unique requirements are the ability to shoot in multiple directions at once, shoot around 90-degree corners, increased importance on the ability to shoot at high and negative elevations, and designing the hull to carry cage armor and/or active protection systems.
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The first, most important, hard factor in an urban tank is its armor. Urban tanks will routinely fight at close range, and so every trick in the book will be necessary to ensure safety and survivability. Armor should be uniformly thick on the front, sides, and rear, since attacks from every angle are to be expected. A pentagon-shaped hull can offer the benefits of sloped armor and V-hulls for protection from mines. A slightly more complex alternative is an octagon-shaped hull, which can offer more angles and smaller flat surfaces for increased shot deflection. Additional armor modules, like cage armor and active protection systems, will not replace or reduce the hull armor’s thickness, and the chassis must be designed to carry them all at once without overloading.
The second hard factor, relating directly to the first, is the vehicle’s engine and mobility. Rather than being built for speed, a tank’s engine will instead resemble a bulldozer engine. An urban tank will be a very heavy vehicle, and so a bulldozer-style engine will be capable of both handling the sheer weight of the vehicle and will allow the tank to overpower obstacles.
Obstacle clearing must be an expected, routine occurrence for urban tanks, and the ability to smash through them and other man-made fortifications without requiring a separate armored bulldozer will be advantageous.
The third hard factor is the tank’s guns. An urban tank will use short-barreled guns, since longer barrels are difficult to maneuver in tight spaces and the tank is less likely to engage in long-range shooting. As a bonus, short-barreled guns are quicker to acquire targets. High-elevation and negative-elevation shooting also benefits from this quicker target acquisition.
An urban tank would have a mixture of gun calibers for its main turret and side turrets/sponsons, since it will need to be capable of firing in multiple directions at once. Side turrets and sponsons will not necessarily require large-caliber guns, but they will require rapid-fire guns. These will often be fired around street/building corners and into buildings from the street to provide flanking fire in support of advancing infantry. Urban tanks may also incorporate a flamethrower in front. The flamethrower would be desirable for covering a tank’s underbelly from attackers in spider holes, tunnel entrances such as manholes, and/or basement windows. It can also thwart attempts to drag mines into the tank’s path and reduce ground-level enemy gun positions designed to provide grazing fire.
A major development in modern tank design is the unmanned turret. As mentioned before, urban tanks must expect enemy fire from multiple directions simultaneously, and thus would benefit from having multiple turrets like a 1920s tank or a pre-dreadnought battleship. The 1920s designs were a failure because the turrets needed to be manned.
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Unmanned turrets, however, allow modern side turrets/sponsons to be much smaller and more compact than their 1920s ancestors, and keep the operators at a safe distance in the event of a direct hit and/or ammunition cook-off. Unmanned turrets can also be placed farther forward on the hull than manned turrets, since they weigh less and thus pose less risk of causing balance/center-of-gravity issues. Placing side turrets further forward, in turn, enables urban tanks to fire around 90-degree corners while exposing as little of its hull as possible. The controls for these would ideally be constructed like the A-10 Warthog’s controls, with redundancy and mechanical backups for all automated systems.
A second soft factor design element is the inclusion of escape hatches on all sides and the rear of the tank, a move that necessitates placing the engine and side turrets/sponsons towards the front of the vehicle.
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Classic urban antitank tactics involve firing down onto the tank from above; while this will be less damaging to an urban tank than a main battle tank on account of its uniformly thick armor, limiting urban tankers to exiting via top hatches noticeably reduces their likelihood of escaping safely when bailing out under fire. This survivability need will also affect the design and employment of cage armor; cage armor designs must not block escape routes, and the escape routes must not widen the cage armor profile any more than is necessary. If the tank becomes too wide, then its usefulness in narrow streets declines rapidly.
They’re not wrong, but such a tank would be hideously expensive.
We still need light, medium, and heavy armored vehicles. What we really need is something very similar to the Finnish Patria NEMO. 120mm direct-fire capable, rifled gun-mortar. Interdict an intersection 5 miles away, drop rounds on the other side of the building you’re next to, put rounds into the windows on that building right over there, then blow up the onrushing VBIED.
Earlier today Samuel Bendett cited a Russian piece on lessons learned from Ukraine:
David Drake (Hammer’s Slammers) and Keith Laumer (BOLO) were prescient. They were both right about what sort of tanks the future might hold, and what those tanks would need to survive.
“Main battle tanks rely primarily upon their speed and long-range firepower”
Starts with an outdated assertion. When you can have precision fire of dozens of km by missile, round artillery, drones suddenly the tank finds itself as a short range weapon.
Then a falsehood, tank speed?! Land movement is always slow.
Any future tank will have to be manufactured in mass numbers in factories with contested supply chains, then transported to whatever shithole proxy war is ongoing where the bridges are rated for max 40 tons. It will be knocked out, recovered, and repaired multiple times before it is discarded and stripped for parts.