Hybrid Air Vehicles CEO Tom Grundy started his career in developing fighter jets and drones for BAE Systems and served as Airbus' project engineering manager during the development of the A380. But now, his focus is on an airplane that can do things that the fixed-wing pilots he admired throughout his life cannot do—even if the basic technology for flying them in the air is much older. Welcome to the second era of airships.

Grundy’s company is promoting its eye-catching, pillow-like AirLander 10, which was originally designed for military surveillance as a pleasant, low-emission alternative to regional air travel. In May of this year, the company announced plans to start serving up to 100 passengers per flight on a few short-haul routes (Liverpool to Belfast, Oslo to Stockholm, Seattle to Vancouver, etc.) starting in 2025. A Scandinavian company is discussing the use of AirLander for trips to the Arctic.

However, the main market for airships in the 21st century will not be passenger services but freight. Compared with helicopters, new airships can carry heavier loads, lower costs, and emit lower emissions than fixed-wing aircraft-if these airships are powered by hydrogen fuel cells, they may achieve zero emissions.

Historically, there were two main types of airships. Rigid airships, as the name suggests, are built around a rigid skeleton. German Ferdinand von Zeppelin (Ferdinand von Zeppelin) piloted the first rigid airship, sometimes called Zeppelin. Another type of airship is non-rigid. Non-rigid airships have no skeleton. They consist of an envelope inflated with a lifting gas such as helium, from which is hung a gondolas for crew, passengers and cargo. The familiar Goodyear airships are mostly non-rigid airships.

The engineers of Hybrid Air Vehicles reviewed the history of rigid and non-rigid airships, and stood firmly on the side of non-rigid-there was a turning point. Unlike the cigars or American football shapes of airships and airships in the past, AirLander looks more like a pillow. A completely different design, it is an elevating body-and heavier than air. It relies on aerostatic lift and aerodynamic lift from helium to fly, making it a hybrid airship. "About 40% of our lift is aerodynamic," Grundy said. "When we turned off the engine and slowed down, we were heavier than air. We landed and landed like an airplane."

The attractive energy efficiency of airships comes from their ability to float in the air, as if a boat is on water-so it seems strange to deliberately erode a mass that is lighter than air. But there is another problem with aerostatic buoyancy. "If you want to ship 50 tons of cargo to remote parts of the world," Grundy said, "and you want to put that 50 tons of cargo in [same location], then you now have to deal with 50 tons of buoyancy." It's like floating underwater. Like a pool, once you release the pressure, it will surge upwards. The airships of the past will be managed by the emission of lift gas (not something you want to do with limited and expensive helium), ballast, and well-designed ropes and mooring procedures. Grundy said that if you want to make money by bringing big things to places with little infrastructure, it's impossible, but he believes AirLander is the answer.

When AirLander made its first flight in Lakehurst, New Jersey in 2012, it was intended as a reconnaissance aircraft for the U.S. Army. The Army cancelled the plan the following year, and HAV took the ship across the Atlantic to Cardington, about 60 miles north of London, for a series of flights in 2016 to test its civilian viability. In November 2017, the vacant AirLander broke away from the mooring mast and deflated. Grundy said that the lessons of this incident led to an improvement in the production model, which is still going as planned. He said: "Our basic business plan is to deliver 12 aircraft per year starting in 2025."

Graf Zeppelin is 776 feet long. According to Wichita State University aerospace engineering professor Brandon Buerge (Brandon Buerge), even non-rigid airships can be huge. He cited the N-class airship of the US Navy in the 1950s, whose mission was to perform anti-submarine and early warning missions. They may be 400 feet long and 120 feet tall, "bigger than anything we often fly," Burg said.

In the early days, the German Zeppelin set an impressive record in terms of safety and capabilities. Graf Zeppelin has flown more than 1 million miles since 1928, circled the earth, and lifted more than 43 tons. "How long did it take for the fixed-wing aircraft to catch up?" Bourges asked. (About 30 years. The C-133 Cargomaster—the U.S. Air Force’s first heavy crane—was put into use in 1958 and can carry more than 55 tons, but it has four turboprop engines that consume more jet fuel.)

Nonetheless, the stiff giant turned out to be fragile in the end. German airships used flammable hydrogen as lift, which led to the Hindenburg disaster. The U.S. Navy’s rigid airship showed a shocking tendency to disintegrate in severe weather. The Germans scrapped Zeppelins at the beginning of World War II, while the U.S. Navy insisted on using non-rigid airships to escort the transport fleet. Facts have proved that the airship is much more resilient. One of the N-class airship "Snowbird" crossed the Atlantic twice and flew for more than 264 hours in various weather conditions, breaking the Zeppelin's endurance record.

"These are the ships they will sail in the ice storm," Burg said. "Non-rigid airships are difficult to kill."

When you approach the Moffett Federal Airport in Sunnyvale, California, you can easily see Hangars 2 and 3 from US 101, their parabolic vertices and huge door frames appear awkward in the relatively flat desert landscape . When you stand between them, looking at them from a distance does not prepare you for their expansive feelings. The huge hangar guides the early summer breeze like a box canyon. In the 1930s, they installed a U.S. Navy airship like Macon, a behemoth 785 feet long and 150 feet high. Recent tenants include the California Air National Guard and NASA.

The current occupants of LTA Research Hangar 2 are using it again to house the airship. On this bright June morning, my tour guide was LTA CEO Alan Weston and LTA Operations Director James McCormick, who acted as the ground line for Weston's seemingly endless energy. In the hangar, a chorus of birdsong echoed from the rafters above the head.

Before us was the bare cigar-shaped skeleton they called the Pathfinder 1 airship, a 400-foot-long spacecraft that could easily swallow the fuselage of the Boeing 737 that took me to California. It is more like an organic sculpture than a body. The lattice structure of black carbon fiber tubes is like the bones of ancient behemoths waiting for the skin of its specimens-in this case, high-tech canvas.

"Isn't that cool?" Weston asked.

His excitement is drawing attention, but in a way he is an ambassador for the return of a strange technology that has been more common in science fiction than in the real world for most of the past 70 years , Although those floating billboards hover over the football field. "Most of my career has been on spacecraft and rockets," Weston said. He designed anti-personnel vehicles for President Ronald Reagan's Star Wars program, and did 23 years of research and development work for the U.S. Air Force. He then served as the project director of NASA's Ames Research Center until his retirement in August 2013.

Retirement did not last long. Later that same year, Google co-founder Sergey Brin asked Weston to create a company to build an airship that could transport cargo in his humanitarian rescue mission.

With the study of the history of airships, Weston's enthusiasm for his new project is getting higher and higher. The Hindenburg disaster of 1937 may be the death of the airship in the popular imagination, but there have been new design efforts every ten years thereafter. (John McPhee’s book, The Deltoid Pumpkin Seed, chronicles the efforts of a strange coalition of former naval airship personnel and ministers of the Presbyterian Church to promote the development of hybrid aircraft/rigid airships in the 1970s. Their ship flew, but no one wanted it. . Their dream of airlifting revolution and missionary work was not realized immediately.)

After he completed the history course, Weston concluded that he could overcome the challenges that plagued the older rigid airships. For beginners, they will use non-flammable helium as the lifting gas. The defects that led to the crashes of naval airships such as Akron and Macon—altimeter failure and structural damage, respectively—can be corrected with modern avionics and strong, lightweight materials. Each of the 13 ribbed carbon fiber "mainframes" that make up the length of Pathfinder 1 weighs only 600 pounds, but together they support a vessel with 28 tons of lift. Damaged carbon tubes can be replaced in flight.

"The beauty of a rigid airship is that you can do almost anything you want," Weston said. "The problem with all these airships is that you don't have any hard points."

Pathfinder 1 will support gondolas, diesel generators, solar panels, batteries, electric motors, and vector thrust propellers, as well as a small gangway running through the length of the outer shell for access to the inner frame. Although LTA will not disclose the size of the Pathfinder 3 it is developing, it will be much more spacious than Pathfinder 1, with enough space for passengers and hydrogen in the passenger aisle-for fuel cells, not for elevators.

In addition to Pathfinder 3, LTA's goal is to build a huge rigid airship that will dwarf the Zeppelin of the past. What LTA will say in its records about its next-generation giant is that it is too big to be built in Sunnyvale-LTA is moving into the former Goodyear Airdock hangar in Akron, Ohio. "AirDock is above this," Weston said, pointing to the ceiling in the distance of Hangar Two. "It's 160 feet tall. AirDock is 200 feet tall."

The ship will not be able to fly until 2023 at the earliest. During this period, Weston and his team have a lot of things to keep them busy, such as after a series of flight tests, fully equipped Pathfinder 1 and fly it to it. Akron's new home is around the San Francisco Bay Area.

Although Weston hopes to start these short "camping trips" this year, it has not yet been arranged. "History is full of airship projects, because people crashed or bad things happened because of people in a hurry," Weston said. "We will be careful."

Igor Pasternak agrees with Tom Grundy's view that buoyancy control is the key to building a commercial airship. Pasternak is the founder of Worldwide Eros Corporation in Montebello, California. He grew up in Ukraine and made tether balloons called aerostats when he was a teenager. He said that airships are "something I have been doing all my life."

However, he believes that relying on aerodynamic lift and vector thrust will limit the airship's ability to operate. The need for a runway, even a short runway, is another limitation. The Aeroscraft Dragon Dream aircraft being built by Worldwide Aeros is a non-cylindrical rigid airship. It uses a different method from Hybrid AirLander, using a low-pressure system to compress and release helium to adjust the lift of the airship-compressing helium, reducing its volume, and then reducing aerostatic lift. Pasternak said, proving that heavy airships can carry out true vertical take-off and landing without ground infrastructure, "we are talking about a huge change in the transportation business, a dramatic change."

That proof has not yet arrived. The design review of the "Dragon Dream" operational validator was only completed last summer, and he did not disclose the time of the next test flight. Like LTA, he is promoting the humanitarian application of airships and has established a partnership with the World Food Program. He hopes to eventually see his invention provide food for famine areas.

The emphasis on philanthropy may help mask the skepticism of some observers. When asked by the aviation analyst Richard Aboulafia whether the new airship company will change the market, he said "hope is eternal". "Frankly, it cannot be expanded," he explained. "The most important thing about air travel is scale, which allows 300 people to fly the 777. You can't do this with these things."

He couldn't think of anyone who needed to send goods at a higher price faster than a ship, but slower than an airplane. Exotic cargo to remote areas is usually a one-way trip. "Air cargo is all about equipment utilization, UPS and FedEx are the best examples," he said. "They have these carefully orchestrated route networks, all of which are for efficient use of equipment, and there are not too many one-way trips."

Weston acknowledged that LTA is in a privileged position. With a non-profit humanitarian mission and the support of some of the wealthiest people in the world, Weston can think again and again about the challenges of flying lighter than air. He wants to build an airship without a carbon footprint, so he hopes to use hydrogen fuel cells in Pathfinder 3 and later. Combining the oxygen in the air with the on-board hydrogen in the fuel cell, you can generate electricity and produce water for consumption and ballast. "When you fly around, you are producing things you want to drink, things to wash your hands and bathe," Weston said. "In fact, we drink water to gain weight. One kilogram of hydrogen produces nine kilograms of water, so we have enough buoyancy control."

He believes that the success of airships in humanitarian relief may stimulate the market more generally. Perhaps low-cost hydrogen-powered cargo airships can stimulate shipping and other industries to transition to hydrogen power. "I think this is a project of a lifetime," Weston said. "In my mind, there are more opportunities to do something useful than anything I have ever seen."

For the aerospace engineer Burg, the helicopter seems to be a reasonable analogy for the new airship. "I don't take a helicopter often, and you may not," he said. But even if the scale of the civilian helicopter market is far smaller than that of the commercial aircraft industry, "I would not call helicopters an unsuccessful technology, or a technology that does not exist at all."

In recent memory, one element of the airship has not been seriously tested: the experience of flying in one.

Buerge used to fly in two airships, Polar 400 and Skyship 600, on a warm summer day. The fixed-wing aircraft would produce fluffy clouds and bumpy journeys. The dynamics are more like a ship than an airplane, the bow gradually rises, the ship slides on the heat wave, and then descends again. Smooth. "For people who are accustomed to flying in aircraft heavier than air, this response will not be interpreted as turbulence," he said. "It's as close to the magic carpet as I have experienced."

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Jon Kelvey is a writer and freelance journalist, focusing on science, health, and aerospace.

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