The concept of a big hot-air balloon carrying things is simple. Fill a bag with lighter-than-air gas and the balloon carries a load | Photo: Hybrid Air Vehicles
Certain designs are ageless or rather their basic design was perfected long ago. The airship — a powered hot-air balloon — was frozen in design between the World Wars. These vehicles could now be on the verge of making a commercial comeback, with the same basic designs modernised by the use of new technologies, and materials.
Consider this. A large vehicle that airlift lots of people and tonnes of cargo, almost silently and efficiently. It needs little power to move loads since it’s buoyant and moves through the low-friction medium of air. It can dock anywhere. It’s very eco-friendly. In contrast to the 1930s, the modern airship is vastly safer since it uses non-flammable gas.
The concept of a big hot-air balloon carrying things is simple. Fill a bag with lighter-than-air gas and the balloon carries a load. The first designs were demonstrated in the late 18th century by the Montgolfier brothers.
Just before the First World War, German aristocrat Graf Ferdinand von Zeppelin added zing to airship design. He started using rigid gas compartments and put in engines, rather than letting the gasbags drift in prevailing wind. Airships are “dirigibles” (lighter-than-air craft) due to the rigid gas compartment.
The problem with the 1930s’ designs was that the “lift” gas used was hydrogen. Hydrogen is abundant and easily produced. But it’s explosively flammable, as anyone who’s touched a match to a hot-air party balloon knows.
Despite this, airships became popular. They crossed oceans, carrying passengers who slept in luxurious cabins, and ate gourmet meals. Disaster struck in 1937. The Zeppelin flagship The Hindenburg, caught fire as it was docking in a field in New Jersey, and 35 passengers died. That was, to put it mildly, bad publicity. By then, airplane design had also advanced considerably. The Second World War led to the design of even bigger planes and then jets took over.
Airship Airlander 10 | Photo: Hybrid Air Vehicles
But there are good reasons for airships to come back. Helium is used nowadays as the lift gas. While helium is much more scarce than hydrogen, it is non-flammable, minimising fire risk. Also, by using hybrid engines, airships are more eco-friendly. Airship manufacturers claim the carbon footprint per passenger is less than 10 per cent that of a jet. Fully electric engines would further reduce carbon footprint.
Airships require zero infrastructure to dock. Actually they just hover, being moored to stakes anywhere convenient. Since airships don’t fly at great heights, they don’t need pressurised cabins either. It’s possible to have open observation decks, where people walk around enjoying 360 degree views.
The Airlander 10
Hybrid Air Vehicles (HAV), which is marketing its Airlander 10 airship and aims to operate these flights
by 2025, says it has a client in Swedish travel firm OceanSky Cruises, which will offer cruises over the North Pole. The fancy modern elements of the 21st century airship are as follows:
They use multiple engines that can be aligned in different ways to give upwards, sideways or downwards thrust, apart from pushing the airship forward, or reversing. Essentially these airships are as manoeuvrable as a giant quad-copter drone. The steering controls and ballast systems are borrowed from submarine technology, allowing them to rise, hover, reverse, or descend rapidly under control. Everything is computerised and sensor-enabled, of course.
The one major downside is, airships aren’t fast. They cruise along at around 80 km per hour, which means journeys take longer than conventional flights.
But if you locate an airship hanger in the middle of town in a convenient field, or on top of a building, it saves commuters the inevitable long journeys to the airport, and the tedium of hours of check-in.
HAV is trying to sell its Airlander 10 to airlines for short-haul trips like Liverpool-Belfast (250 km), Vancouver-Seattle (190 km), etc. The 100-seater has a cruising speed of 80-90 km per hour and an altitude ceiling of 2,000-2,500 metres. It stays aloft indefinitely without using power.
Airlander 10 adapts a design used for surveillance in Afghanistan. The company says the craft would be ideal for journeys of up to 350-400 km and hopes to sell 265 craft over the next 20 years.
Zeppelin, which still exists as a company, runs 12 commercial airship services, on trips across mountainous bits of Germany and Switzerland. Lockheed Martin is working on a design to carry massive amounts of cargo.
The US Defense Department is funding research into heavy payload dirigibles as well, while mining companies
are also interested in these. Airships may work well as cargo haulers, where speed is not of the essence. They offer connectivity to remote places inaccessible for trains, cars and ships, without the expense of building airports. So, more than a century after Zeppelin first unveiled his gigantic gasbags, we might see its descendants take over the skies again.