As large, fast-moving, and heavily armed behemoths, tanks are the primary offensive weapon of modern armies. And for the past 100 years, engineers have been locked in an arms race to protect their own tanks and kill others. Typically, protecting tanks has consisted of adding new, increasingly heavy armor plating. But kinetic active protection systems, such as the Russian ARENA system in this video, are growing increasingly popular.
Over the past century, the average weight of tanks has quadrupled. One of the first tanks, "Little Willie", weighed in at 16.5 tons; the modern American M1 Abrams weighs approximately 70. Most of that weight is armor, and as effective as that's been to keep tanks alive, it comes at a cost in size, weight, speed, and mobility. Over the long term, increasing a tank's size and weight is unsustainable.
In the 1970s the armies of NATO fielded a new generation of anti-tank missiles. The Soviet Union, to protect its investment in a numerically superior tank force, began researching countermeasures. One was the concept of the active protection system, or APS.
APS involves ringing a tank with sensors, typically millimetric wave radars set up to detect incoming rockets and missiles along the tank's frontal arc. Once an incoming anti-tank round is close enough, the APS launches an interceptor rocket to take out the incoming rocket or missile. Active protection systems are lightweight, effective, and cost less than adding more armor to a tank.
The video above shows the Russian ARENA system at work using ultra-high-speed 18,000-frames-per-second cameras. Developed by the KB Mashinostroyeniya Design Bureau located outside Moscow, ARENA automatically detects incoming targets at approximately 50 yards and has a .07 second reaction time. Anti-tank rockets and missiles, like the Russian RPG-7 and the American TOW, travel at up to 300 yards per second, making them slow enough to be intercepted (but too fast for the system to be operated manually). ARENA-equipped tanks have are equipped with between 22 and 26 interceptor rockets. Interception takes place approximately 10 feet away from the tank.
Other nations are catching on to the APS concept. Israel's Trophy system protects Israeli tanks from rockets and missiles in terrorist hands, South Korea is equipping its K-2 Black Panther tank with a domestic version, and a shift back to big-power warfare (particularly versus the Russians) has the U.S. Army testing APS with Abrams tanks and Bradley infantry fighting vehicles. APS systems will almost certainly be part of the next round of upgrades for both, as well as the Stryker interim armored vehicle.