US Army Spending Big On Woke Hybrid-Electric Abrams

But there are drawbacks, too. One of them is the need for a large lithium battery pack. Battery packs are heavy and expensive and they also are dangerous because they can explode if hit by shrapnel or if a mine blows out the tank's bottom. While we don't know the size of the battery the Army will opt for, it will have to be big enough to power a heavy tank – meaning the battery could weigh a few tons. This creates a vulnerability that does not exist today and raises questions on whether it makes sense to go in the hybrid direction.

In addition to exploding and burning batteries, an important question is field servicing. In warfare, engines under great stress can be damaged or burn out and need to be replaced. In a modern modular power pack, it is possible to replace the entire assembly in a few hours – even in the field.

There are a few reasons why exchanging engines and other power components on a hybrid tank could be near to impossible. While the engine itself can be lifted out, it will be fitted with high voltage cables and connectors that require the battery to be safely disconnected and capacitors discharged before the engine can be removed. How this will be done in the field is an open question.

Even more troublesome are the electric motors that power the tank. These will be on the tank's underside, connected to the drive wheels. If the electric motors are damaged it is most likely the tank will have to be towed away, put on some kind of transit gurney and sent to a repair depot with equipment capable of lifting the tank so it can be serviced.

Electric motors on tanks will be heavily stressed, far more so than is the case with any conventional vehicle. No one today can say anything about the long term reliability of an electric drive motor that will need to start and jump off multiple times on the battlefield. While electric motors are famous for generating a lot of torque, moving 67 tons or more of tank on the battlefield will stress the moving parts of these engines as never before.

There are many ancillary questions as well. Electric motors are heavy and need to be mounted on assemblies that can hold the weight and deal with the torque from them. This means that the tank's suspension will need considerable work to accept electric motor drives – and the drives themselves will add additional weight where you don't want it, on the road wheels. How this will translate on soft ground or in rainy or snowy conditions is hard to say, but it can mean that the tank will dig itself in more easily than a conventional drive train.

Electric and hybrid electric vehicles require specialized liquid, closed-loop cooling systems for the electronics. The Abrams today does not require a cooling system, and other tanks such as the Merkava are air cooled. Leopard tanks require two radiators.

A lighter tank is an attractive alternative but powering it with electric motors and lithium batteries introduces its own problems and headaches that may make the Abrams X experiment
just that, an experiment.

Other countries have been experimenting with hybrid electric power packs, but have not adopted them. Israel, beginning around 2016, developed a hybrid version of the Merkava tank, but it did not go in the hybrid direction. Its new Merkava 5 has a turbo-charged MTU diesel rather than a gas turbine.

While Russian tanks have had autoloaders for the tank's cannon since 1967, the US and UK have not adopted them. The Germans had planned a future autoloader for the Leopard, but never implemented it.

An autoloader adds some mechanical and electrical complexity to a tank, but it can reduce the typical crew size from four to three. It also opens the door to various approaches to robotic or autonomous tanks in the future.

Abrams X is supposed to have an autoloader and feature a three-person crew. The US has virtually no experience in autoloading 120mm shells.

Abrams X is planned to be equipped with a built-in active defense system.

There are very few Abrams tanks today with active defense systems and all of those systems are add-ons. The Army has purchased the Israeli Trophy system, but in relatively small numbers.

One of the questions regarding active defense systems is the ability to deal with drone strikes. Drones are typically slow-moving when compared with missiles and rockets or tank rounds. On the modern battlefield, drones can approach from virtually any angle and often are launched in batches. Any modern active defense system needs practical ways to destroy drones and would work best if networked with other tanks with active defense and non-tank air defenses. Whether that is part of the plan for Abrams X is not clear.

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One limitation of a built in active defense system is that changes and upgrades are difficult once the system is physically embedded in a tank hull. Active defense is still a young technology and in need of growth and improvement. As artificial intelligence gains a bigger foothold in military systems, tank protection is likely to be extremely important, especially since AI in a network can improve overall tank protection.

Will Abrams X Be Adopted

There is a lot of hype about Abrams X as a future main battle tank. There is little doubt that a lighter tank would work better in most conflicts, although light tanks bring their own vulnerabilities – especially susceptibility to drones and other“cheap” weapons. The case for a hybrid electric platform is one that remains to be proven. Despite some advantages, hybrids also introduce operational, security and logistical issues that are far from being mitigated.

The US Army today is“woke” and one of the reasons to push hundreds of millions of dollars in research and development of the hybrid electric tank is related to ideology instead of necessity. In fact, any study of tank warfare in Ukraine is unlikely to support the case for a hybrid electric platform, since the main tank vulnerability is visual discovery of tanks by FPV Drones, not because they are heat sources.

There is no evidence the US Army has taken into account the lessons of the Ukraine war and worked on systems to kill drones that are playing havoc with US and European tanks.

A future system would include a networked capability to kill drones and counter air-launched mines. Spending money on a hybrid electric platform is a mistake mostly because it avoids confronting the real issues on today's and future battlefields.

Stephen Bryen served as staff director of the Near East Subcommittee of the US Senate Foreign Relations Committee
and as a deputy undersecretary of defense for policy.

This article was first published on his Weapons and Strategy Substack and is republished with permission.

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