How the ‘jack-in-the-box’ flaw dooms some Russian tanks

A destroyed Russian T-72 tank in Ukraine's Kyiv region on April 1. (Oleksandr Klymenko/Reuters)

By Sammy Westfall and William Neff-April 30, 2022

The sight of Russian tank turrets, blown off and lying in ruin along Ukrainian roads, points to a tank design issue known as the “jack-in-the-box” flaw.

The fault is related to the way many Russian tanks hold and load ammunition. In these tanks, including the T-72, the Soviet-designed vehicle that has seen wide use in Russia’s invasion of Ukraine, shells are all placed in a ring within the turret. When an enemy shot hits the right spot, the ring of ammunition can quickly “cook off” and ignite a chain reaction, blasting the turret off the tank’s hull in a lethal blow.

Sitting on a powder keg: The T-72 tank’s fatal flaw

Other tanks on the modern battlefield generally store their ammunition away from the crew, behind armored walls. The Russian T-72 main battle tank’s ammunition sits in a carousel-style automatic loader directly beneath the main turret and members of the crew.

T-72 (Russia, Ukraine)

Tank commander

Gunner

Driver

If a penetrating hit on the tank’s relatively thin side armor detonates one of these rounds, the explosion can set off

a chain reaction, killing the crew and destroying the tank.

Leopard 2 (Germany)

M1 Abrams (United States)

Sources: “M1 Abrams vs. T-72 Ural” by Stephen Zaloga (Osprey Publishing, 2009); “Leopard 2 Main Battle Tank 1979–1998”

by Uwe Schnellbacher and Michael Jerchel (Osprey Publishing, 1998); Federation of American Scientists

WILLIAM NEFF/THE WASHINGTON POST

In Ukraine, destroyed Russian tanks are the newest roadside attraction

“For a Russian crew, if the ammo storage compartment is hit, everyone is dead,” said Robert E. Hamilton, a professor at the U.S. Army War College, adding that the force of the explosion can “instantaneously vaporize” the crew. “All those rounds — around 40 depending on if they’re carrying a full load or not — are all going to cook off, and everyone is going to be dead.”

British Defense Secretary Ben Wallace this week estimated that Russia has lost at least 530 tanks — destroyed or captured — since it invaded Ukraine in February.

What to know about the role Javelin antitank missiles could play in Ukraine’s fight against Russia

“What we are witnessing now is Ukrainians taking advantage of the tank flaw,” said Samuel Bendett, an adviser at the Center for Naval Analyses, a federally funded nonprofit research institute. Ukraine’s Western allies have provided antitank weapons at high volume.

Ukraine, too, has been using Russian-made T-72 variants, which face the same issue. But Russia’s invasion has relied on the large-scale deployment of tanks, and Ukraine has been able to fight back better than expected.

The flaw speaks to a broader difference in approaches between Western militaries and Russia’s, analysts say.

Why Russia gave up on urban war in Kyiv and turned to big battles in the east

“American tanks for a long time have prioritized crew survivability in a way that Russian tanks just haven’t,” said Hamilton. “It’s really just a difference in the design of the ammo storage compartment and a difference in prioritization.”

Ammunition in most Western tanks can be kept under the turret floor, protected by the heavy hull — or in the back of the turret, said Hamilton. While a turret-placed ammunition storage compartment is potentially vulnerable to a hit, built-in features can prevent the same level of decapitating devastation seen in the case of the T-72.

Even the early versions of the American M1 Abrams tanks in the 1980s were fitted with tough blast doors separating the crew inside from the stored ammunition. These tanks have a crew of four, including a loader who opens the ballistic door manually. These were designed to be stronger than the top armor, so that if ammunition is cooked off, the explosion would be channeled upward through blowout panels, rather than into the crew compartment, Hamilton said.

On the battlefield, Ukraine uses Soviet-era weapons against Russia

On the other hand, Russian tanks rely on mechanical automatic loaders, allowing them to be manned by a team of three.

The design of Russian tanks prioritizes rate of fire, firepower, a low profile, speed and maneuverability vs. overall survivability, said Hamilton. Russian tanks tend to be lighter and simpler, and have thinner, less-advanced armor than Western tanks. The design vulnerability was probably “just cheaper and lighter,” Hamilton said.

Newer Russian models have come out since the T-72, which was produced in the 1970s by the Soviet Union. One of them, the T-14 Armata, has been described as a sophisticated battlefield game-changer since it debuted at a 2015 military parade. But the Armatas have not yet seen much use outside parades. Newer variants of the T-72 have come with greater tank protections, Bendett said, but the prevailing principle has been the same: a three-person crew with a lower profile, and shells in a circle within the turret.

 Washington Post Pentagon and national security reporter Karoun Demirjian explains the difficulties of deciding which weapons to send Ukraine. (Video: Joshua Carroll/The Washington Post)

Understanding the weapons that have drawn the world’s attention since Russia’s invasion of Ukraine

For the U.S. military, Hamilton said, “if the tank is destroyed and the crew survives, you can make another tank more quickly than you can train another crew.”

For Russia, “the people are as expendable as the machine,” he said. “The Russians have known about this for 31 years — you have to say they’ve just chosen not to deal with it.”

Claire Parker contributed to this report.