Tanks are evolving, albeit slowly. Tank armour and protection systems have come a long way. However, cannons haven’t changed much. Tank barrels have increased in diameter, with this trend continuing in the latest generation of tanks. However, the limit for practical round size has more or less climaxed. So what could be the next step to increase the lethality of cannons?
Firstly, let’s look at why tank cannons are still relevant in the age of guided missiles.
- Velocity: Rounds fired from tank barrels are much faster than ATGMs. For instance, the Rheinmetall Rh-120 can launch rounds at over 1700 meters per second. In comparison, the AGM-114 Hellfire travels at around 450 meters per second. Although unguided, there are circumstances where the speed of tank rounds is advantageous.
- Cost: The price of each projectile adds up. Particularly in prolonged wars. Tank rounds will always be much cheaper than guided missiles.
- Versatility: HE(high-explosive) tank rounds can effectively destroy differing targets. These include vehicles, infantry clusters, hideouts, buildings, barricades, etc. Whereas most guided missiles are only suitable for use against other land vehicles. General-purpose guided missiles exist, but they perform best when fired from air platforms. Besides, not only do they cost a lot more, but they don’t provide a significant advantage in a line-of-sight ground-to-ground situation.
- Resistance: ATGMs are highly susceptible to hard and soft-kill APS. Tank rounds, meanwhile, are impervious to soft-kill countermeasures. Most hard-kill systems can also struggle to disable an incoming tank round.
- No minimum range: In some situations, the enemy is much closer than anticipated. Guided missiles have a minimum range requirement, which can prove to be an annoyance. Tank rounds, on the other hand, can eliminate targets that are a stone’s throw away. Literally.
The issue with current guns and their proposed successors
Today’s MBTs use 120mm or 125mm cannons. Their projectiles are capable of penetrating older tanks. However, decent current generation MBTs can withstand a frontal impact. As main battle tanks are designed primarily for conventional warfare, they must successfully engage and defeat tanks belonging to the opposing force. For this reason, military decision-makers are looking at 130mm, 140mm or even larger calibres for a solution.
Even a minor increase from 120mm to 130mm can provide a 50% increase in performance. The extra weight aids with penetration. However, this comes at the cost of space, and consequently, total round capacity. The roughly 10kg increase in weight, means that without an autoloader, loading the gun will be slower.
With more propellant, a 130mm round can travel marginally faster than a 120mm round. But the improvement would be nearly unnoticeable.
An increase in diameter may indeed be the most simple solution. But apart from the superior penetration, it’s hardly an upgrade?
Electrothermal-Chemical (ETC) Cannons
Electrothermal-chemical guns use plasma to ignite the propellant. This has several key advantages:
- Increased rate of expansion
- Muzzle energy increases
- Greater muzzle velocity
- More predictable igniting pattern
- The utilisation of advanced and higher density propellants
- Existing tank barrels and rounds can be used (saves resources)
Electrothermal-chemical guns can be the next giant leap in cannon technology. Large bore guns need an evolutionary step forward, and the many advantages provided by ETC technology is phenomenal.
Though the technology is in its infancy, it’s theoretically feasible for ETC guns to launch projectiles at almost railgun-like speeds. High-density propellants lit with plasma will fully ignite at a fast rate. They will also burn in a more predictable pattern. Meaning more energy will be generated, leading to projectiles travelling at blistering speeds.
Unlike railguns, which require large batteries to operate, ETC guns don’t need nearly as much power. Current tank barrels are compatible with ETC technology, which further increases the viability and cost-effectiveness of ETC guns.
Several ignition methods exist. The preferred method is FLARE (Flashboard Large Area Emitter). However, its complexity has made it the main focus of R&D efforts on ETC technology. There is a good reason for this, however. In the XM291 tests, the FLARE ignitor launched rounds with 17 MJ of muzzle energy (with 120mm rounds). Though already impressive, further advances could see this number rise. That puts the ETC 120mm barrel variant of the XM291 well within 140mm territory in terms of muzzle energy.
Electrothermal-chemical guns are an evolutionary step forward. Though they offer a plethora of benefits, there are also some drawbacks. Including the need to integrate systems that take up precious space inside cramped tanks. However, the biggest hurdle is the hesitance to dedicate resources to the R&D of ETC technology. Whether it’s the simplicity of switching to larger barrels, or the allure of railguns, ETC technology is almost unknown in the defence community.