Dirigible Dreams

Image credit: Courtesy Lockheed Martin

When a 7.0 earthquake hit Haiti in January, the island’s tiny airport became a huge bottleneck for relief supplies. But someday, rescuers may have another option: an airship that could land off-airport with a load larger than a current cargo airplane’s, at significantly less cost. And that day might come sooner than you’d think.

Four years ago, a strange, bloated contraption moved out of Lockheed Martin’s hangar in Palmdale, California, and skimmed its way to the runway. Looking more like an inflated bath toy than an aircraft, with four stubby landing feet extending from its bulbous, tri-lobe shape, it waddled and bounced its way off the runway and into the air.

Lockheed’s P-791 prototype might not look like the next cool frontier in aviation. In fact, its wide, tri-lobe shape, which allows its body to generate lift, is the high-tech descendant of an idea that engineers, inventors, and crackpots have pursued since the Civil War. And by the end of 2011, something like it may be a fixture in the skies over Afghanistan, hunting down the improvised explosive devices that cause up to 70 percent of the combat casualties there.

The idea of a tri-lobe airship dates back to 1863, when Solomon Andrews flew the Aereon, a triple-hulled, gravity-powered airship he hoped to develop for military and commercial use. The war’s end took away the driving need—and funding—for a controllable reconnaissance vehicle.

Undaunted, Andrews built a single-hull airship that moved sideways. To explain how the craft flew, he published a booklet subtitled “Without Eccentricity, There Is No Progression.” Andrews may not have meant the double entendre, but his statement was prescient, for the evolution of airships has been marked by the efforts of many eccentrics.

In the 1960s, a passionate Presbyterian minister started the Aereon Corporation to build a tri-hull airship to haul missionary cargo, but the craft never got off the ground. Aereon’s next effort, a triangle shape that writer John McPhee dubbed the “Deltoid Pumpkin Seed,” was a hybrid, meaning it got some of its lift from its aerodynamic shape, and the rest from its engine. The prototype flew in 1971, but again, no funding for development followed.

Why have so many airship projects failed to get off the ground? In part, says Jim Thiele, president of American Blimp, which worked with Lockheed on the P-791, it’s because airships look deceptively simple, attracting dreamers with visions bigger than their technological expertise or ability to deliver. And those failures have given airships a “giggle factor” that makes it difficult for other companies to obtain development money or contracts.

Technical obstacles also abound. Traditional blimps require ground crews and mooring equipment, and they’re notoriously squirrelly on the ground. Moreover, off-loading heavy cargo without re-ballasting presents problems for lighter-than-air vehicles. But fly-by-wire technology, vectored-thrust engines, hybrid designs, and new superstrong, superlight materials have solved many of those challenges. Lockheed’s experimental P-791, for example, is a hybrid and uses a hovercraft-type landing system that cushions the landing and then reverses to “suck” the craft down on the ground for off-loading.

So if the technology is there, why haven’t we seen advanced airships and hybrids taking to the skies? In part, politics—it’s hard to displace existing technology that has entrenched camps of support. And no need has been great enough to justify the expense of development and to overcome those political hurdles—until now.

“I don’t think it’s airship technology that’s changed as much as the services have come around to an interest in what the airship offers,” says Air Force Colonel Paul Hastert, one of the Pentagon’s lead officers on the new Long Endurance Multi-intelligence Vehicle the military wants in Afghanistan by the end of 2011. The unmanned LEMV will reduce the need for risky special-ops reconnaissance missions by staying “on station” at 20,000 feet for three weeks, with high-resolution cameras and sensors that can backtrack from an explosion to find who planted the bomb, and where they went. No existing platform can do that.

And if the LEMV becomes an accepted part of the military air fleet, it might pave the way for a cargo version that can fly faster than a ship sails, carry more than an airplane, and land almost anywhere.

As Solomon Andrews observed, the path of forward progress is sometimes less than straight.