At the turn of the millennium, the German company Cargolifter AG was promising to construct a gigantic airship capable of lifting a 160-ton payload—the first of a revolutionary new class of flying cargo transports. Enthusiasts dreamed that fleets of such airships – a catchall term for vehicles popularly known as “blimps,” which are an airship subset – might soon dot the skies. Yet, by June 2002, Cargolifter was insolvent, and the investors who had poured more than 300 million euros into the project might have felt that they had spent their money on the Hindenberg.

The Cargolifter debacle was just one of the most recent and spectacular failed attempts to build a commercial airship industry. For most of the past century, believers have touted dirigibles’ efficiency and ability to land in difficult terrain as reasons to use them for cargo transport. Airships have also had environmental appeal: unlike polluting, diesel-burning jets, they can, in theory, run on many fuels, or even solar power. Nevertheless, airships were always weighted down by the iconic images of the Hindenberg engulfed in flames and remained marginalized to advertising – think the Goodyear Blimp – and tourism. A flurry of recent developments backed by major aviation companies and the U.S. military, however, has some zeppelin fans hopeful that advanced technologies and rising environmental concerns could help launch an airship renaissance.

The dreaded “A” word

The first thing to understand about these new vehicles is that their makers often recoil from calling them airships—“the A word,” jokes Gordon Taylor, director of sales for Hybrid Air Vehicles (HAV) in Cranfield, England. He and his peers at other companies prefer to call their vehicles “hybrids” because they combine lighter-than-air with other aviation technologies. The helium (not dangerously inflammable hydrogen) that fills hybrids offsets only a portion of their weight. Aerodynamic lift provides the rest of the buoyancy during flight, as air flows past the hybrids’ flattened, winglike fuselage, and vertical thrusters may provide a further assist for control.

Gallery: A new breed of hybrid airships

Since hybrids need to burn fuel to keep themselves in the air, why would you want to make them less buoyant? Conventional airships need sizeable support crews at either end of their journeys because, as cargo and passengers unload, extra ballast must be added to offset the weight change and prevent the vessel from floating away. Hybrids eliminate the additional ballast requirements.

By contrast with hybrids, “Airships will never be able to do cargo properly,” Gordon-Taylor said. “It’s pure physics.”

Military airships

Such improvements, and new military interest in hybrids, have given momentum to commercial projects. In 2010, for example, the U.S. Army awarded a $517-million contract to Northrop Grumman and HAV to build three Long Endurance Multi-Intelligence Vehicles (LEMVs) for intelligence missions in Afghanistan. Those vehicles might normally carry a crew of three, but they could also reportedly be shifted to a heavy lifting configuration that could haul a 17-ton cargo, comparable to the capacity of a Lockheed Martin C-130E, one of today’s largest fixed-wing transports. HAV is also separately working on designs for three commercial hybrids with 20-, 50- and 200-ton payload capacities. Gordon Taylor says that HAV would be able to have one of these flying and certified within 36 months.

Meanwhile, Lockheed Martin, which lost out on its bid for the LEMV contract, has announced that it is developing a “SkyTug” with a 20-ton payload capacity for Aviation Capital Enterprises, a Calgary-based company. The SkyTug is scheduled for commercial availability in 2013 and could be followed the next year by a SkyFreighter with a 50-ton capacity.

Aeros, based in Montebello, Calif., is working on its own distinctive hybrid concept that would regulate their buoyancy with gas compressor systems that could remove helium from an internal envelope and compressed it in tanks to reduce buoyancy during landings, then re-expanded again for flight. This system would allow true vertical descents and liftoffs, unlike other hybrids that would still need some room for takeoffs and landings, according to Edward Pevzner, Aeros’s business development manager. He says the company will demonstrate a working vehicle in 2012Many other companies around the world, with names such as Millennium Airship, Skyhook International, Helios and E-Green Technologies, have announced plans for their own vehicles.

The economic case

But will hybrid airships make economic sense? Airships, including the hybrids, fall into an uncomfortable slot between shipping alternatives because their projected airspeeds typically top out around 100 miles per hour. Customers who care about cost more than speed may continue to prefer to use less expensive trains, ships and trucks, while those who prioritize moving their cargo quickly may see a better bargain in jets.

Hybrid company representatives acknowledge that their vehicles will not be competing for normal bulk transport business—at least not initially. Taylor says that HAV is first targeting commercial freight markets burdened with “stranded assets” in hard-to-reach locations. Hybrids might be highly economical solutions for logging or building pipelines in northern Canada, for example, where seasonal waits for the right time to build roads and move materials could be prohibitively expensive and time-consuming. Offshore wind farms would also periodically need to receive deliveries of massive equipment, such as 65-meter-long turbine blades, and a huge oil discovery off Brazil’s Atlantic coastline and ongoing infrastructure projects deep in the Amazon also beckon. Hybrid makers’ hopethat proving the worth of the vehicles for exotic uses will open the door to other possibilities. “Once these things become commonplace, then people will begin to say, ‘What if?’” Taylor says.

Even for those stranded-asset jobs, hybrids may face competitors and other headaches, however. Large cargo helicopters, for example, such as the Boeing Vertol 234, can carry payloads up to 20 tons at almost 150 mph and land vertically, too. Hybrids are also big: for one to get near the ground at some wooded or rocky sites, the operators may need to clear a landing space several times the size of a football field.

A luxury travel vehicle?

Tom Crouch, aviation historian and senior curator of the National Air and Space Museum in Washington, D.C., believes in the value of hybrid airships for the surveillance and intelligence missions that the military plans for them but takes a more skeptical view oftheir other uses. He notes that airship proponents have been unsuccessful in winning business in other areas, “which suggests to me that the economics just may not be as good a fit.”

Joseph A. Dick, an independent aviation consultant who worked in airship development for many years, is more dismissive of the rationale for hybrids on fundamental engineering grounds. Airship dynamics simply involves too much air resistance at speeds relevant to commercial transportation, he says, and according to the figures he has seen, the problem is worse for hybrids than for dirigibles. “Putting wings on airships or making them an odd shape to generate aerodynamic lift just doesn’t make sense.”

Dick does recognize one market where airships could succeed: the luxury air travel business, in which passengers willing to pay a premium price could cruise over the Atlantic at leisure and in high style. That, of course, was the Hindenberg’s business model, too.

John Rennie served as editor in chief of Scientific American between 1994 and 2009. Based in New York, he continues to work as a science writer and editor, and as an adjunct instructor in New York University’s Science, Health and Environmental Reporting Program. John blogs at The Gleaming Retort can be found on Twitter as @tvjrennie.