How it Works

When sensors on the helicopter detect an incoming rocket-propelled grenade (RPG), tubes on the chopper fire between one and eight rockets toward the incoming RPG. Each rocket deploys a Kevlar-and-steel net, which inflates like a parachute as it flies, forming an impenetrable barrier between the helicopter and the grenade.

_How do you prevent insurgents from shooting down choppers? How do you keep a cast from itching? How do you reinvent the brick? You sketch. And then you work: nights, weekends–for years, if you have to. You blow all your money, then beg for more. You build prototypes, and when they fail, you build more. Why? Because inventing is about solving problems, and not stopping until your solution becomes real.

This week, we begin rolling out the winners of the 2007_ PopSci_ Invention Awards. We’ll be doling out a new innovation each day for the next few weeks, so keep checking back for more of what the world’s brightest inventors are currently cooking up. And if you just can’t wait, pick up a copy of the June issue that just hit the stands.-Eds.


Name: RPG Net **

****Inventor:** Richard Glasson**

Cost to Develop:** $10,000

Time: 2 years

Prototype | | | | |

Last January, a Black Hawk helicopter flying in rural Iraq burst into flames, killing all 13 soldiers on board. A few days later, a helicopter owned by a private security company crashed in Baghdad, killing five civilian contractors. Over the next few weeks, six more aircraft were shot down, leaving 11 more dead–one of the worst series of chopper disasters since the war began.

Although the Army won’t attribute any crash solely to an RPG-insurgents typically fire guns at the craft as well–the simple, unguided, shoulder-launched projectiles are widely believed to be the primary anti-chopper ordnance of the insurgency.

New Jersey inventor Richard Glasson thinks he can stop the attacks. He’s designed the first-ever anti-RPG system for aircraft: a volley of nets that catch the grenades before they hit. Glasson was inspired by Mark Bowden’s best seller Black Hawk Down, which recounts the 1993 killing of 18 U.S. soldiers in Somalia after an RPG brought down their chopper. “I couldn’t believe that such a low-tech weapon could take down a several-million-dollar aircraft,” he says. “That’s a spectacular outcome for a 40-year-old technology.”

Fourteen years later, still the only defense helicopters have against RPGs is avoidance: “either flying too high or too unpredictably to be targeted,” explains John Pike, director of, a military think tank in Alexandria, Virginia. Other countermeasures, such as radar jammers and flares, are worthless against unguided weapons like RPGs.

Defense companies are working on systems that would fire projectiles at the grenades to destroy them. But that’s “like hitting a bullet with a bullet,” says Glasson, who is the chief engineer at Control Products, a company that designs sensors for aerospace and defense. (He’s worked on sensors that protect gearboxes from overheating on the president’s Marine One choppers and in jet engines on most commercial airliners.) So he devised a defense that, like its target, is surprisingly simple. Since RPGs are far slower than heat-seeking missiles and are easily knocked off course, he set out to build a system that would block or at least deflect the grenades before they reached the chopper.

The key is launching that barrier in time. An RPG will detonate four to six seconds after being fired (unless it hits a solid object–then it detonates on impact). In Glasson’s system, the chopper’s radar calculates the speed and trajectory of an incoming grenade within milliseconds. Half a second later, pods of launch tubes on the helicopter aim and fire between one and eight unguided yard-long rockets on an intercept course with the grenade. The rocket’s aim doesn’t have to be precise because each drags a braided steel-cable parachute woven with Kevlar. In the next second, these fast-opening chutes inflate to form a series of six-foot-wide bombproof nets, catching the grenade and dragging it to the ground.

“He might really be on to something here,” Pike says. Glasson won’t know for sure until he can test the nets on a real helicopter, and for that he needs the backing of the Pentagon or one of its big contractors. Two years ago, Pentagon officials told him that the agency was more interested in pursuing a laser-based defense system, which is years from realization, but Glasson hopes the recent spate of crashes will convince them to take another look at his idea. Retired chopper pilot Lt. Col. James Bullinger, an editor at Army Aviation magazine, thinks they will. “When it comes to saving lives,” Bullinger says, “they will spend the money on it.”

More Invention Awards:

  • A Six Strokes of Genius – An engine that uses steam to squeeze more miles from gas
  • A Chopper Shield – Catches helicopter-bound grenades with a net made of Kevlar and steel
  • A Big Ball of Connectivity – An antenna that blows up like a balloon brings satellite communications anywhere, anytime.
  • The New Velcro – A stronger, better grip without the incessant ripping sound. Has a long-standing dream finally been realized?
  • A New Breed of Mouse – Give your mouse the finger to control your computer in three dimensions
  • The Flying Belt – Rappel up a wall at an astonishing 10 feet per second with the Atlas Powered Rope Ascender