Next-Generation Abrams Tank & Stryker To Be Hybrids

October 7, 20222 years ago Jennifer Sensiba 0 Comments

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Warfare has never been great for the environment. The United States military, being the biggest example, emits more greenhouse gases than a number of industrialized nations. To be fair, the US military protects some of those countries through global alliances, effectively shouldering some of their emissions, but the important point here is that the big machines and long distances involved with today’s defense activities are a major contributor to climate change.

Some Background On These Vehicles

In some ways, it’s difficult to imagine warfare without the things that cause all of these emissions. Ideally, we wouldn’t need things like tanks and armored personnel carriers at all, but the Cold War led to a lot of competition.

In the 1960s, the US Army and West German Army worked together on a single design to replace both the M60 tank and Leopard 1. To match new Soviet tanks like the T-62, as well as improved protection against the T-62’s new 115 mm smoothbore gun and especially high-explosive anti-tank (HEAT) rounds, the objective was for a single new design with greater firepower. They knew that if they failed to produce a better tank, hordes of Soviet tanks could pour through the Fulda Gap and overwhelm NATO.

After a number of setbacks and redesigns, the answer came down to designs by Chrysler and GM in the XM1 tank competition. By mid-1976, the decision to implement GM’s design was largely made. There were worries about Chrysler’s turbine engine both in terms of reliability and fuel consumption, in addition to concerns about overall performance. Overall, GM’s program was less expensive at $208 million compared to $221 million for Chrysler. But, politics came into play and senior Pentagon officials demanded a turbine engine, even though that meant lower reliability and higher fuel consumption. This tank became the M1 Abrams.

While the feared Soviet invasion and World War III never happened, the tank proved effective against Soviet designs during the first Gulf War, with Saddam Hussein’s tank forces finding themselves out of range while taking a pounding from the Abrams.

Unlike the Abrams, the Stryker infantry carrier was developed after the Cold War, and was part of efforts to adapt the US military to adapt to new realities. The introduction of an Interim Armored Vehicle (IAV), which was intended to fill the gap between heavier and heavily armed, but not readily deployable, vehicles such as the M2 Bradley and lightly equipped, readily deployable vehicles like the Humvee, was planned. The IAV was designed to act as an interim vehicle until light air-mobile vehicles from Future Combat Systems’ Manned Ground Vehicles program became available. But, that program was canceled before anything could come of it.

A variant of the Canadian LAV III, an armored personnel carrier, won the competition. With 8 wheels that can operate in 4-wheel-drive (making it an 8×4), or in all-wheel-drive (making it an 8×8), the vehicle can go over most terrain while protecting the personnel it carries. The Stryker’s powerpack consists of a Caterpillar diesel engine, which is used in other US Army medium-lift trucks. By using this type of engine, it eliminates the need for extra training for maintenance crews and allows for the use of common parts. In about two hours, the engine and transmission may be removed and reinstalled, allowing for repairs to the turbocharger as well as numerous other components to be done outside the vehicle.

While they’ve seen mixed success, variants of the vehicle have proven useful in urban areas to safely carry and deploy infantry.

Problems With The Power Units For These Vehicles

One problem with the Abrams was known from the beginning: fuel consumption. While fears of turbine maintenance proved to be unfounded, the tank still burns a lot of fuel. The engine consumes more than 1.67 US gallons (6.3 L) per mile (60 US gallons (230 L) per hour) when driving cross-country, and 10 US gallons while idling. This means that the military needs to come up with and transport a lot of fuel to keep them running.

Efforts are underway to reduce fuel consumption, both with a better main engine and an auxiliary power unit with its own little rotary engine that would eliminate the need for long idling sessions. But, there’s still a lot of room for improvement when it comes to fuel consumption.

The Stryker, being a lot smaller and running on a more efficient diesel engine, doesn’t have the fuel consumption problems, but it still suffers from limited range (310 miles). It also has the problem of noise, as a diesel engine’s clatter is well-known and easy to pick out of a noisy urban environment compared to the Abrams’ turbine engine.

The Solution For Next-Generation Designs: Electrification

General Dynamics Land Systems recently announced some important upgrades for the next generation of Abrams and Stryker vehicles. By using hybrid powerplants, not only are problems solved, but the vehicles get exciting new capabilities. While the big motivation for reducing fuel consumption is to get better range and lower logistical challenges, the Pentagon does also have climate goals.

The AbramsX has a new hybrid powerpack that cuts fuel consumption in half, which is great for both emissions and for fighting. It also allows the tanks to sit silently but still be ready for action. General Dynamics also says that the tank will have limited silent mobility, meaning that it can run for short distances with the combustion engine off. This will make the tanks a lot more sneaky.

The StrykerX gets similar benefits from its diesel hybrid setup. They say it’s going to have silent watch and silent movement, but they didn’t say that silent movement was “limited,” so the Stryker might have more electric range. Its power unit can also “export” power, which means it can run as a generator for a variety of tasks that could come up in both warfare and some humanitarian missions. It’s also supposed to be less crampy inside (or, if they don’t care whether it’s cramped, room for more people).

While it would be great to see these vehicles eventually go full BEV, and not have what the Toyota Prius had two decades ago, it’s still a big step forward for such large vehicles. It also shows us that the military is taking progress toward electrification seriously.

Featured image provided by General Dynamics.