For decades, the return of lighter-than-air craft has been an evergreen subject for publications large and small. I wrote an airship story for The New York Times in 1987. The New Yorker ran one in 1973 and another in 2016. The Economist runs one every few years. And prompted by the quest for low-carbon/no-carbon transportation, there’s been a new spate of stories in publications ranging from The Guardian to Fodor’s Travel – even Foreign Policy. Enter “airship” in the search field on YouTube and you’ll be rewarded with endless video footage of blimps, dirigibles and hybrid lighter-than-air craft. Some of them are even real.

Where you won’t commonly see airships is in the sky. The Goodyear blimp still floats above sporting events, although only in Europe for now. And an outfit in southern Germany offers tourists scenic zeppelin flights over Lake Constance, Munich and the Rhineland. But aside from a few short test voyages, large airships have been a no-show.

It’s not for lack of trying. At least half a dozen companies are pursuing lighter-than-air transport, with names ranging from the fanciful — Flying Whales — to the formidable — Lockheed Martin. Their websites all suggest that airships are a solution for hauling heavy cargo or for sustainable commercial travel, not just for flying advertisements above football games or riesling cruises above the Rhine. But many have not updated their sites in years, and notably, not one of these companies responded to an interview request.

There is a reason that development efforts persist, however, if only sporadically. Airships have some inherent advantages over conventional aircraft. They require no runway, so they can take off and land almost anywhere, and they burn less fuel to get off the ground and stay aloft. An airship could hover above a city after a natural disaster to provide communications services. In theory, a large airship could lift bulky items and deliver them to locations inaccessible to conventional cargo aircraft. But somehow, the economics never work out.

“My non-economist’s idea is if there were a business case for airships, we’d already have them,” allowed Dan Grossman, an aviation historian and keeper of the website airships. “You need someone to risk the capital to build a workable ship.”

Don’t Mention the Hindenberg

Every article about airships has to mention the Hindenberg. Who am I to resist?

As Grossman recounts on his website, the fiery crash of the British airship R-101 in October 1930 (in which passengers and crew were killed by the hydrogen fire that followed the crash rather than by the impact) prompted the German Zeppelin Company to alter its plans for a hydrogen craft and develop a ship capable of being lifted by helium, which is far less explosive.

Since helium is heavier than hydrogen, it therefore provides less lift. So a helium airship must be larger than a hydrogen airship to carry an equivalent payload. And Germany’s Zeppelin Company took the fact to heart. LZ-129, aka the Hindenberg, was 803.8 feet long, with a diameter of 135.1 feet. LZ-129 and its sister ship, LZ-130, are still the largest objects ever to fly.

But despite the design brief, the Hindenberg was filled with hydrogen rather than helium, which allowed it to carry more passengers and freight. By the end of 1936, it had safely crossed the Atlantic 34 times, carrying 66,000 pounds of mail and freight — and, more important, 3,500 passengers in great luxury. With swastikas painted on its tail, the giant dirigible embodied Nazi ambition.

But as the Hindenberg was landing in New Jersey on May 6, 1937, a spark (presumably caused by static electricity) ignited leaking hydrogen. The resulting fire killed 35 persons on the airship and one member of the ground crew. Miraculously, 62 of the 97 passengers and crew survived.

There had been previous airship crashes with greater loss of life — notably, one destroying the USS Akron in 1933. But the Hindenberg disaster was caught on film. Millions viewed the horrific images, and the era of zeppelin travel came to an abrupt end.

Grossman believes it would have ended soon thereafter anyway. “Despite its romance and grandeur, the Hindenburg was obsolete before it ever flew,” he writes. “Between the cost of its infrastructure and crew, inherent safety issues and the development of better technology, the rigid passenger airship was doomed long before Hindenburg landed at Lakehurst that fateful day.”

A Gasbag by Any Other Name

The R-101, the Hindenberg and the Graf Zeppelin were all dirigibles, with rigid metal frames surrounding self-contained gas cells. Dirigibles do not rely on the pressure of the lifting gas to maintain their shapes, so they can be larger and fly higher. A blimp, by contrast, has no internal structure, so if it deflates it loses its shape. The eponymous Goodyear blimp, used primarily to advertise the company’s rubber products, is the best known. But blimps have also played a military role, with the U.S. Navy employing them for anti-submarine surveillance well into the 1950s.

Confusing matters, the current Goodyear airship is not a blimp but a zeppelin, built by a descendant of the same German company that fabricated the Graf Zeppelin and the Hindenberg. The Zeppelin model NT 07 (NT as in neue technologie) is the only advanced airship that has been certified and is flying regularly in commercial passenger service (for Goodyear and tourists, anyway). It has a semirigid frame of carbon fiber and aluminum, so it can fly higher and is more maneuverable than the blimps of yore.

These modern-day zeppelins are really hybrids, stronger and more capable but more costly than blimps, yet smaller and less costly than the great dirigibles of the 1930s. They are also hybrids in the sense they rely partly on swiveling propellors to allow vertical takeoffs, hovering in place and flying backward. Some of the prototype airships currently being tested take hybridization one step further, actually relying on forward motion and an aerodynamic shape to provide part of their lift.

These airships fly “heavy,” which helps keep them from soaring upward when their cargo is offloaded. Or that would be the case if any of them were actually airborne. As noted in a three-part report published in April by the Lyncean Group of San Diego:

No full-scale prototypes are flying: The airship firms currently have little more than slide presentations to show to potential investors and customers. … The airship firms are depending on potential investors and customers making a “leap of faith” that the “paper” airship actually can be delivered.

First as Tragedy?

One of the more popular airship videos on YouTube is the crash of Airlander 10. This is no Hindenberg going up in a fireball. But on its second test flight, the Airlander 10 did a slow-motion nose dive, hitting the ground face first. None of the crew was hurt, but it can’t have been reassuring to potential passengers or investors. The following year, Airlander 10 tore free from its moorings in a high wind, automatically pulling a safety rip panel so that it deflated and fell to the ground. No one was on board, but two people on the ground sustained modest injuries.

The Airlander 10 was actually repurposed from the HAV 304, a joint project of U.K.- based Hybrid Air Vehicles and Northrop Grumman, which beat out a Lockheed Martin submission for the U.S. Long Endurance Multi-Intelligence Vehicle project. Bedeviled by delays and cost overruns, the project was canceled in 2013, and the HAV 304 project reverted to Hybrid Air Vehicles. The company is now working on a much larger airship, Airlander 50, which it says will be able to carry 50 tons of freight or 200 passengers. But as you have surely guessed by now, that craft has yet to fly.

At least the Airlander 10 video shows an actual airship in flight, something conspicuously absent in many companies’ promotional materials. Lockheed Martin’s Hybrid Airship website is long on staged interior shots and computer-generated imagery. The aircraft flying in Egan Airships’ video is a radio-controlled model. Dirisolar’s video has pretty pictures of castles, waterfalls and the Grand Canyon, but the footage of its airship is animation. Best for laughs is an old episode of Top Gear, where James May goes “airship caravanning,” crash landing in what is actually a blimp-shaped hot air balloon with a propellor.

The most functional airship in all of the online videos is the current Goodyear blimp, which as noted above is actually a $20 million Zeppelin NT. It’s a capable vehicle with a theoretical ceiling of 10,000 feet, although the Goodyear pilots say they like to keep it between 1,000 and 2,000 — the better to be seen. And it is remarkably maneuverable, the better to shoot video at NASCAR races. But the video also shows its limitations. The airship has a crew of 20 who follow along in two large trucks, and it requires a clearing of 500 feet so the wind can blow it around in a circle at its mooring mast.

The Hydrogen Conundrum

The Goodyear zeppelin’s propellors are driven by internal combustion engines, the venerable Lycoming 0-360, a four-cylinder piston engine that has powered thousands of fixedwing conventional aircraft including the Cessna 172 and Piper Cherokee. The Airlander 10 was powered by the RED A03, an all-aluminum V-12 motor, which is also used in many contemporary airplanes, including the de Havilland Canada DHC-2 Beaver. The Lycoming runs on avgas (the fuel used in prop planes), while the RED runs on aviation kerosene. So much for zero carbon.

Promotional materials for the new airships tell of electric motors — someday, some way — but they’re vague about how that will work. Lifting the tons of lithium-ion batteries needed to power them would force a corresponding reduction in cargo and passengers, with the added attraction of range anxiety. Moreover, lithium-ion batteries sometimes catch fire spontaneously, which is why the FAA no longer allows them in checked baggage.

Some airship pioneers talk of harvesting sunlight from photovoltaic arrays mounted on the upper airship surfaces, but the feasibility has yet to be demonstrated. So the most plausible renewable-energy solution is to power the motors with fuel cells. Which brings us back to hydrogen.

In the U.S., Canada and Europe, aviation regulations only allow the use of nonflammable lifting gas, which rules out hydrogen for that application. It is legal to carry hydrogen in a high-pressure container to power any vehicle including an airship — but not if it’s carried in a zero-pressure container (gas cell) to lift the airship. All currently operating airships, their makers will hasten to tell you, are filled with helium. But helium, as noted earlier, is heavier than hydrogen and so has less lifting power. It’s also vastly more expensive, a differential exacerbated by a global helium shortage, which impacts not only airships, but also MRI machines, fiber-optic cables and, of course, kids’ birthday party balloons.

Barry Prentice, a would-be airship entrepreneur and professor of supply chain management at the University of Manitoba, says the solution is obvious: bring back hydrogen, both as a fuel and as a lifting medium. He points out that there are already thousands of vehicles in use that run on hydrogen — buses, forklifts, trains, cars and ferries — and that it is safely used in many industrial applications. Prentice’s embrace of hydrogen makes him an outlier. But he insists there’s no reason it couldn’t be used safely to lift airships, and it would make them much more efficient, thanks to its greater lifting capacity.

“Hydrogen will give you eight percent more gross lift,” Prentice says. “We’re envisioning a 30-ton lift airship; 50 percent is dead weight, so you need 60 tons lift to have 30 tons marketable. Eight percent more gross lift equals 15 percent more cargo lift, and that goes right to the bottom line. Helium is … a rare commodity,” he reminds us. “When it’s gone, it’s gone. So hydrogen really is the key.”

The killer app for airships, Prentice says, is transporting cargo, including fresh fruit and vegetables, to Canada’s north. Climate change means traditional ice roads are experiencing ever-shorter seasons of use, while the construction of all-weather roads is prohibitively expensive. Flying Whales, a French company that has received government support, touts its proposed airships as a way to harvest timber where forest roads are lacking, a similar application. Some aficionados have suggested that airships could service offshore wind turbines.

Prentice started a company, Buoyant Aircraft Systems International, which flew a helium-filled prototype successfully. But his dreams are on hold since a freak windstorm destroyed the craft and its hanger in 2016.

While he continues to publish papers in peer-reviewed journals explaining the promise of lighter-than-air flight, Prentice holds out hope that a deeper-pocketed airship enthusiast, Google co-founder Sergey Brin, who is building a zeppelin, will crack the design puzzle. “We need somebody like that to take the risk because it doesn’t matter if he loses it all.”

With All the Money in the World…

Brin’s airship aspirations have been an open secret since 2018. A proxy filing by Alphabet, Google’s parent company, disclosed that Alphabet leases hangar space at Moffett Airfield, a former U.S. Navy base close to Google’s Silicon Valley headquarters, to a company named LTA Research & Exploration, “which is owned by an entity affiliated with Sergey Brin.” Lighter Than Air (LTA) Research is an aerospace research and development company building experimental and certified manned and remotely piloted airships.

According to TechCrunch, LTA’s first crewed prototype airship, called Pathfinder 1, will be powered by batteries when it takes to the air, possibly this year. FAA records show that the Pathfinder 1 has 12 electric motors and would be able to carry 14 people. The company plans to retrofit hydrogen fuel cells in this and subsequent aircraft, according to job listings.

“Functionality-wise, there is no showstopper to using a hydrogen fuel cell,” Professor Dr. Josef Kallo of the German Aerospace Center, told TechCrunch. “The challenge is to find someone who can afford not to look at the business case, because I don’t think it works out from an economic perspective. Maybe Sergey Brin can afford to do that.” Definitely, not maybe: Brin is currently the ninth richest person in the world, with a net worth of over $86 billion.

Indeed, Brin’s company says its goals are not commercial:

LTA airships will have the ability to complement — and even speed up — humanitarian disaster response and relief efforts, especially in remote areas that cannot be easily accessed by plane and boat due to limited or destroyed infrastructure. We ultimately aim to create a family of aircraft with zero emissions that, when used for shipping goods and moving people, would substantially reduce the global carbon footprint of aviation.

LTA is hiring, but be sure to bring your sense of humor to the interview. LTA’s employee listing on LinkedIn includes a dog named Dr. Guacamole, who graduated from the Bergin Institute of Canine Studies in 2017.

Up in the Air

Covid-willing, two or three advertising blimps will soon return to U.S. skies and they will make people smile. Folks on TripAdvisor rave about Zeppelin NT’s low and slow flights. I hitched a two-hour ride in an advertising blimp 30-odd years ago, and I smiled the whole time.

And maybe that’s the secret to airships’ enduring allure. There may be no compelling business case, but the world would be a little poorer without them.