Just Don't Call it a Blimp

It's a hybrid airship—part plane, part dirigible. Two Ohio inventors think production versions up to 990 feet long will launch a new era of aviation—one where low and slow is the way to go.

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The future of aviation is wobbling. Looking like a giant albino queen ant, the 117-ft.-long Dynalifter airship trundles down a grass airstrip in eastern Ohio, its white, ovoid envelope bobbling with each clod and divot in the runway. Undersize wings poke out from the airship's midsection, ailerons fluttering, as co-inventor Brian Martin steers from a cannibalized ultralight cockpit slung under the canopy. He turns the ship around at the end of the runway, lines it up with the main axis of the strip and throttles up the twin 100-hp Rotax 583 engines. The great bobbing mass accelerates slowly until it is lumbering along at 30 mph.

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Martin's partner, Robert Rist, rides 100 ft. behind in an SUV, watching carefully. "If we go much faster, we're going to get airborne," he says. Ultimately, of course, that's the goal, but since the men haven't yet obtained the Federal Aviation Administration sign-off to take their prototype into the air, they're careful not to break the rules. After a couple of high-speed taxi runs, Rist and Martin decide that they've pushed the envelope as far as they can today. With the help of a team of volunteers, they maneuver the grandiosely named Dynalifter back to its open-ended, cloth-and-tubing hangar. Built with donated parts and $500,000 in cash, the craft has the somewhat wonky aspect you might expect from a first-time effort: The sailcloth skin has a bumpy, uneven appearance, and bugs of every description are stuck in the tape that holds the cloth together.

Yes, it's a little rickety-looking. But if Rist and Martin succeed, it won't be the first time a pair of amateurs from Ohio with a rickety aircraft has turned the world of aviation upside down. "I want to say this with all humility—there's a Wright brothers aspect to this," Rist claims. "We have a vision of the future, and we have legs."

They may be on to something. The Dynalifter is among a wave of aircraft so revolutionary that the FAA has yet to figure out exactly how to classify them. Combining characteristics of both dirigibles and airplanes, these so-called hybrid airships could open new frontiers of transportation by carrying huge loads vast distances in much less time than would be possible by surface vehicles—and to deliver these loads just about anywhere, even to the middle of roadless wilderness. Not only enormous weights, but bulky and outsize objects, such as giant radar antennas or prefabricated buildings, could be moved between continents.

One major potential customer: the military. In 2004 DARPA, the Pentagon's research arm, released a request for proposals under its Walrus program, which explored the feasibility of hybrids. DARPA -envisioned craft that would carry an entire military unit halfway around the world and deliver it to an unimproved landing area within seven days. Defense giant Lockheed Martin is also working on a hybrid airship.

Rist and Martin—or, for that matter, DARPA and Lockheed—aren't the first visionaries to pin their hopes to a gas-filled craft. The history of aviation is littered with airships that never got beyond the prototype stage. Will the idea ever truly, well, get off the ground?

The major difference between hybrid airships and old-fashioned dirigibles can be summed up in a single word: weight. Blimps, zeppelins and all other lighter-than-air vehicles rely on a lifting gas—usually helium—to keep them floating. Hybrid airships use gas to generate 30 to 80 percent of the lift they need to get off the ground, and depend on aerodynamic lift—the flow of air over wings or fuselage—for the rest. That means that when hybrids stop moving through the air, they sink. The advantage? Once on the ground, they stay put. A major problem for conventional airships is the difficulty in handling them on the ground. Large and buoyant, they're always eager to fly away on the slightest breeze. The Goodyear blimp requires 17 handlers; the zeppelins of the '20s and '30s employed hundreds.

A hybrid airship can land itself. "You can turn off the master switch, turn the key, walk away," says Edward Pevzner, the business development manager for Worldwide Aeros, a small California company that builds blimps and is also currently investigating hybrid airships. "You come back in the morning and it's still in the same place."

The same is true of a jet cargo plane, of course. And a jet is much faster than a hybrid airship, which is limited to about 100 mph, thanks to its huge, draggy envelope. But because it generates much of its lift passively, a hybrid airship has a higher fuel efficiency—no small advantage in a time of soaring energy costs. "The basic thing to know about the Dynalifter," Martin says, "is that it's fuel-efficient."

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True, it will take longer to get anywhere. Rist and Martin calculate that their planned 990-ft.-long production model will require two days to carry a 160-ton payload across the Atlantic. But not everything needs to be delivered by tomorrow morning. Rist and Martin foresee a day when Dynalifters fill a niche in long-distance transportation between air freight and surface. Freshly caught fish and live vaccines could cross the ocean by 747, pig iron and wheat could cross by freighter, while cargo such as fruit and high-end fashion could cross by hybrid airship. "The Dynalifter will fill the market that trucking would normally handle," Rist says, "but do it out over the ocean."

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Such claims have a familiar ring to them. The world's passionate legions of dirigible enthusiasts—those ever-hopeful "helium heads"—have long touted conventional airships as the cargo craft of the future. But, in addition to ground-handling problems, blimps and their ilk require copious amounts of ballast in order to keep from rising or sinking uncontrollably. If a zeppelin, for instance, unloads 100 tons of cargo, it needs to take on 100 tons of ballast at exactly the same rate—a difficult and potentially treacherous requirement. Thanks to a hybrid airship's negative buoyancy, that's not a problem.

Remarkably, neither Rist nor Martin is an aerodynamicist, or even a pilot. Neither had ever built an aircraft before starting their prototype. They met while both were working in the technology department at nearby Mount Union College and became excited enough about the idea to quit their jobs in 2003 in order to pursue it full time.

The real innovation of the Dynalifter concept, Rist and Martin say, is on the inside, where a patented structural system lends the craft unusual rigidity and strength. Supporting its aluminum internal frame is a longitudinal spar reinforced by stays from a central mast, like the span of a cable-stayed bridge. This spar will allow the Dynalifter to carry not only heavy loads, but compact ones, such as an M1 tank. "If you tried to hang a tank from a blimp," Rist says, "the blimp would sag in the middle."

Though hybrid airships are enjoying unprecedented attention today, the idea is not new. Back in the late '60s, a New Jersey company built a 27-ft.-long, propeller-driven lifting body called the Aereon 26 that was designed to be filled with helium. Described by The New Yorker writer John McPhee in his book The Deltoid Pumpkin Seed, the Aereon 26 made several flights without the gas, but failed to generate enough investor enthusiasm to spawn the gigantic successors that its inventor envisioned.

Two decades later, a British company called Advanced Technologies Group (ATG) began developing a hybrid blimp it called the SkyCat, which it said could carry 1000 tons more than 4000 miles. In 2000, ATG successfully flew a 42-ft.-long, remote-control scale model called the SkyKitten. But the company went bankrupt soon after.

To aerospace industry skeptics, there are good reasons hybrid airships have persistently failed. For one thing, unlike jets, airships operate most efficiently at low altitudes, where they are subject to the vagaries of weather. And then there's the speed issue. "It's as slow as molasses in January," says aviation consultant Scott Hamilton of Leeham Co. "I think it would be nothing more than a niche market—carrying unusual cargo or some type of passenger service. But the last time a blimp was in regular passenger service, it was called the Hindenburg."

Others, though, see the airship boosters' vision as plausible. Jack Olcott, the retired president of the National Business Aviation Association, is one of the few people to have ever actually flown a hybrid airship, having served as the Aereon 26's test pilot. In terms of performance and handling, he says, the craft compared quite favorably to traditional blimps. "The hybrid airship has a very interesting set of characteristics that would make the vehicle suitable for special-purpose missions," Olcott says.

As for why the idea has failed to catch on so far, he points out that bringing any aircraft program through to production is expensive and time-consuming. "Add to that a new level of technology that isn't backed up by reams and reams of empirical data," he says, "and you can understand how difficult it is to move forward. Investors want certainty. When you're experimenting with new concepts in aircraft, the likelihood of getting a high degree of certainty is low."

DARPA saw enough promise in hybrids to spend $6 million of its Walrus funds on preliminary studies by Lockheed and Worldwide Aeros. The Worldwide Aeros Walrus design incorporates a rigid structure that, in addition to generating 30 percent of the craft's lift through aerodynamic forces, would use vectored thrust provided by turbofans or ducted propellers. "It will be all-weather operational, unlike other airships," says Worldwide Aeros' Pevzner. The company is also studying what Pevzner calls a "dynamic buoyancy management system" that would operate during "all stages of flight to make the aircraft at some moments heavier and at some moments lighter. You can call it ballast, but it's not ballast. I cannot go into the exact details." The technology may be a compressor, or a gas-generation device similar to ones NASA has explored for airships used in space.

Lockheed Martin has been even more circumspect, declining a request by Popular Mechanics to discuss its plans for the Walrus project. In late January the company conducted an intriguing 5-minute test flight of a hybrid airship called the P-791, which resembled three blimps fastened alongside one another. The ship was driven by a pair of propellers on its tail and another two on its flanks; instead of wheels, it taxied on four Hovercraft-like cushions. Lockheed says the P-791 is part of an internal research program and not linked to Walrus.

If it ever gets built, a full-scale Walrus vehicle would be at least 900 ft. long, four times as long as an Airbus A380, and capable of lifting 500 tons of cargo and fuel. Such a vehicle could be a mainstay of the Pentagon's Future Combat System, which over the next decade is supposed to reorganize the Army into a networked and highly responsive force. But the craft's future is in doubt. With money and attention shifted to the war in Iraq, DARPA suspended further funding for the program in April. When the preliminary studies were completed last month, Walrus shut down.

And so, with all its competitors in the deep freeze or headed there, the pair of underdogs from Mantua, Ohio, has ascended to leadership in the hybrid airship race.

A month after their first taxi tests, on a muggy June morning, Rist and Martin sit in their open-ended hangar alongside their great white aircraft. In an adjacent field, small birds dart after insects amid the soybean stalks. Once the FAA gives the green light, the two men can fly the Dynalifter as an experimental aircraft. Meanwhile, they can only wait—and share with a visitor their dream of a world transformed by their simple vision. In the not-too-distant future, they say, hybrid airships will be as ubiquitous and as essential as trucks. Cities will spring up wherever the Dynalifter Corp. decides to locate its hubs, and the world's economies will be tied together by a global transportation infrastructure of Dynalifters.

"In the long term, this kind of transportation system is inevitable," Martin says. "If the Dynalifter doesn't succeed, something else like it will."

What do you think?