Airships, the fall and the rise: why the dirigible won’t die
Image credit: Airlander
The history of the airship is fraught with failure, so why - seemingly against all reason - does the aviation world refuse to give up on dirigibles?
“That’s us,” I announced with undeniable pride, directing the taxi driver to a large airship parked at the far side of the airfield. I enjoyed seeing his look of awestruck surprise. The 60m-long, 20m-high blimp, rigid with more than 6,000m³ of air and helium, looked magnificent in the early morning sunshine. It was easy to be impressed.
I was flying across the United States, from Florida to California, in the world’s largest commercial airship, the British-designed Skyship 600. The 12m-long gondola slung under the envelope would usually have been filled with seats for up to 13 passengers, in addition to the two pilots, but we were instead using the airship as a platform to conduct various atmospheric science experiments as we crossed the American continent. Powered by two 230hp Porsche 930 engines, the Skyship promised a top speed of 60 knots in calm conditions, but most of our journey was spent at a more sedate cruising speed of 30 knots or less. The outboard propellers, called vectors, on either side of the gondola are mounted onto helicopter props to allow rotation between horizontal and vertical positions. They can tilt 85° up and 110° down to provide a surprisingly steep take-off (enough to tilt back the seats as if firing astronauts into space) as well as greater hover, flight and descent control.
Airships are irrefutably nostalgic. By blending the glamour of flight with the promise of adventure, they have the ability to capture both attention and imagination.
Whether – as an invention – they deserve this continued adoration is more debatable. Our trip was continually blighted by the limitations of the airship. It was true the speed and stability of the Skyship made it an ideal platform for our science – certainly more suited than the higher speeds of an aircraft or the greater vibration of a helicopter. Yet despite being capable on paper of staying aloft for more than 24 hours without refuelling, no single flight we made in the blimp during our month-long voyage was ever longer than a few hours and some were cut as short as 20 minutes.
We were regularly halted and diverted from our route by unfavourable weather, contrary winds, clouds, heat, cold or altitude. Perhaps the most restrictive factor of all was the ability of our ground crew to keep up. As a lighter-than-air craft, the airship cannot land unassisted. Instead it has to power itself towards a waiting team, positioned in a ‘V’ shape on the landing strip, who literally pull the airship out of the sky using ropes trailing from the envelope. The Skyship needs a ground crew of at least 14 to land it safely. It is then secured to a mobile mast raised on the back of a truck. This means the airship can only ever travel as fast and as far as its ground crew and mast. The ground crew was delayed by traffic or mishap more than once during our journey, leaving us helplessly circling above an airfield waiting for them.
Once attached to the mast, the airship is at its most vulnerable. Deteriorating weather and winds can place huge strains on its structure. Avoiding damage requires constant attention from ground crew, which isn’t without its dangers. The airship is capable of swinging unpredictably around the mast, causing injury to anyone in the way, and can even leave the ground at a 45° angle – an alarming manoeuvre known as ‘kiting’.
Rather than sailing across the continent in a graceful ship of the skies, our journey felt more like limping erratically across the States with a wildly temperamental white whale. My experience made it easy to understand why airships have never become a mainstream form of transport. Ever since Henri Giffard flew a steam-powered dirigible a distance of 17 miles (27km) in 1852, airships have been enthusiastically pursued as the solution of the future in many functions. Notably, a high proportion of these quests have ended unceremoniously in costly, and often fatal, failure.
At the turn of the 20th century, airships were touted as the ideal conveyance for Polar travel and, indeed, the Italian semi-rigid airship Norge flew over the North Pole in 1926 – but later flights ended in tragedy. During the First World War, airships were trialled extensively in many military applications by both sides but, ultimately, their vulnerability led to development being abandoned in favour of aeroplanes.
Between wars, the Empire State Building in New York was completed with a dirigible mooring mast forming its now famous spire in anticipation of regular Zeppelin trans-Atlantic passenger services. The scheme never materialised due to safety concerns. The US military were the only armed forces to make use of airships in the Second World War, establishing a programme that included convoy support, surveillance and cargo transport. The programme was continued by the US Navy after the war, with airships forming part of the early warning systems of the Cold War, but was shut down in 1963.
The 1980s were the heyday of modern airships, as Goodyear built its famous blimps that floated above stadiums and major events across the world, employed as filming platforms, advertising space and for occasional passenger pleasure flights. The events of 9/11 brought this role to an end as the US banned blimp flights over stadiums. The advent of drones, which are now more commonly used to film aerial shots, dealt the final death blow.
Today there are fewer than 10 commercial airships flying worldwide and contracts are scarce. Having failed to find its forte in everything from border patrols to whale watching, it would seem the age of the airship is decisively dead. Yet, search the internet today and you will find dozens of concept designs for space-age dirigibles, from behemoth transporters shaped like static manatees, to planetary orbiters resembling airborne spinning tops. Even internet retailer Amazon has revealed itself to be an airship visionary, recently filing a patent for high-altitude airships as ‘airborne fulfilment centres’ that despatch deliveries by drone. Multiple websites say ‘the future looks bright’ for airship technology and an era of dirigible supremacy is right around the corner. Why, seemingly against all reason, does the aviation world refuse to give up on airships?
Peter Buckley is one of the most experienced airship pilots in the world, having accumulated more than 22,000 hours in command. He is acutely aware of the deficiencies and complexity of airship design, but is equally confident it would be a mistake to ignore advantages promised by dirigibles. “We’re not willing to give up on airships because of the potential on paper,” he says. Buckley believes it has been a lack of belief rather than a lack of capability that has stymied the airship’s commercial success. “There is nothing wrong with modern airship design,” he contends. “It is a victim of size and cost and trying to persuade people the concept is a risk worth taking. In the past, the only people who could afford to invest in airship design were the military. No one in commercial industries would put in that kind of money unless it was a proven concept and shown to work, even if they could see the potential.”
Given the failure of successive attempts to make airships profitable, it could be argued that investors are right to be cautious.
“You need a billionaire who decides this is their plaything or a government who can subsidise it,” agrees Chris Daniels, head of partnerships and communications at British company Hybrid Air Vehicles (HAV). “We have a US Army contract that provides $100m-worth of research and development for free. Without it, we wouldn’t be in the position we are in now.”
The company specialises in hybrid airships, craft that are lighter-than-air, but also benefit from aerodynamic lift. A prototype was developed for the US Army’s Long Endurance Multi-intelligence Vehicle programme in 2012, but it was cancelled six months later. HAV modified the design for general production and the resulting Airlander 10 prototype took its maiden flight last year; a foray that ended in a humiliating ‘heavy landing’.
To many, this inauspicious start might be a sure sign that the Airlander is doomed to the familiar dirigible fate but Mike Durham, technical director at HAV, believes the hybrid nature of Airlander offers something different. “The fundamental problem is that airships float. Floating things create engineering problems. They are susceptible to wind shifts and weather. The premise of Airlander is that we don’t float, we’re heavier than air. We are effectively flying.” At 92m long, the Airlander is the longest aircraft in the world. It gains most of its buoyancy from the helium filling its 38,000m3 envelope, but the elliptical cross-section of its hull provides 40 per cent of its lift aerodynamically. The greater control this affords when landing, combined with the thrust of its four 325hp turbocharged diesel vector engines, means a ground crew of just six is needed. HAV plans to reduce this even further until the craft can land without assistance, complete with an on-board mast.
“There’s a bunch of people nostalgic for airships in the same way they are nostalgic for Concorde or the Vulcan bomber,” says Durham. “We never use the word airship to deliberately get away from that romanticism. We are a hybrid air vehicle. We don’t want to be associated with that romantic era of the blimp. This is the future, not a resurrection of the past.” Yet the optimism in little more than a concept, the declarations of innovation and the promise of reinvention, all sound ominously familiar.
HAV believes cargo transport is the niche in which airships will excel. Airlander has a 10-tonne payload but the intention is to “produce a range of hybrid aircraft capable of carrying up to 1,000 tonnes”. The firm sees applications in heavy industry and pipeline repair, particularly in areas with little existing infrastructure such as Africa and the far north of Canada.
It’s a good idea, but one that has failed in the past. British designer Roger Munk was commissioned to build 22 new airships for a South American government to carry cargo into the continent’s interior in the 1970s, but the scheme floundered early on due to failure of a prototype in high winds. “Most aeronautical engineers don’t understand the reality of lighter-than-air craft,” concedes Daniels at HAV. “A lot of people have over-hyped airship solutions. Any application is going to take a lot of preparation. A critical mass of a type of airship is needed before there is a viable market.”
Despite this warning, HAV is not the only company betting on cargo transport as a lifeline for its airships. California-based Worldwide Aeros Corporation has developed the Aeroscraft, a rigid airship designed specifically for the purpose. Like Durham at HAV, Aeros CEO Igor Pasternak is confident he has identified the key flaw of previous airship design and he can offer something better. “The biggest obstacle that conventional and hybrid airships face when tackling the cargo function is their inability to control buoyancy,” he states. “The requirement for ballast exchange, ground infrastructure and need for runways significantly limited the usefulness of traditional lighter-than-air vehicles for cargo applications.” Consequently, the Aeroscraft features a ‘control of static heaviness’ (COSH) system that enables buoyancy to be varied. By pressurising helium within the envelope to reduce lift, Aeroscraft can remain lighter-than-air during flight, but become heavier when needed, such as when offloading cargo, conveniently removing the need for ballast during cargo exchange. The Aeroscraft also has a landing system similar to a hovercraft. By passing air through 70m-long air cushions beneath the envelope, the landing system can grip the ground to make itself secure and the suction capability can be adjusted to adapt to a range of surfaces, including water.
The concept is undeniably clever, but still doesn’t resolve many of the well-established flaws of airship design, such as the need for hangars and infrastructure, the cost of development or vulnerability to wind and weather. The company announcements heralding an ‘innovative and revolutionary aircraft’ with ‘game-changing potential’ that will ‘reinvent air cargo transport’ feel a little premature – and perhaps unduly optimistic – given the Aeroscraft has not yet been built. Trials have been conducted on a half-size prototype called ‘Dragon Dream’ instead.
Advertising has arguably been the most successful use of airships in the past. One company is combining this history with technology that might at first seem to be in direct competition with the blimp. “It’s a blimp but with modern drone tech,” says Daniel Meier of Aerotrain, a Swiss company that produces Skye, a small blimp that looks like a giant floating eyeball. “It gets its buoyancy from helium, but with drone technology we can control it.”
Bucking the trend for supersized prototypes, Aerotrain has capitalised on small and embraces traditional limitations of the airship. Skye is a 3m-diameter sphere of polyester and polyurethane fabric filled with 6.8m3 of helium. It can only fly in calm weather, has a flight time of just two hours, a maximum altitude of 1,600m and its regular drone motors can produce a top speed of only 15km/h. Nevertheless, Skye can carry heavy camera, projection and illumination equipment, making it the ideal tool for advertising, filming and crowd interaction. People can touch and interact with Skye because its low-power design with enclosed motors means that it is intrinsically safe. “Even at full speed, there is not enough impact energy to knock you out,” reassures Meier.
Aerotrain has now begun developing industrial applications, but Meier is realistic about their prospects. “We are expecting it to be a niche market,” he says. “A niche can be small, but powerful.”
Drone-blimps may offer a way forward for airships towards profitability, but because they are designed to be flown remotely and are more suited to indoor spaces, many might dispute their status as a ‘real’ dirigible. One can’t imagine the Skye eliciting quite the same excited response from a taxi driver as the Skyship 600.
Having looked closely at the latest wave of airship innovations, nothing has been found that leads one to believe our skies will soon be filled with dirigibles, but plenty to suggest that the world is quixotically unprepared to give up on its airship vision of the future. Airships have repeatedly proven to be costly, unpredictable and hopelessly impractical, and yet this seems to be its appeal. As veteran airship pilot Peter Buckley admits: “It’s the only seat of the pants flying that’s left.”
Perhaps the inherent capriciousness of the airship and the challenge of its technical complexity is the very reason we seem unable to let this particular bad idea die.