Phoenix Rises – Return of the Airship

Spy balloons over the US and Canada, with some being shot down, have been a major news story in recent months. But what is not in the mainstream news is the spotting of what appears to be the world’s largest airship hangar in China – with an airship taxiing.

Chinese giant airship hangar and airship. BlackSky

The purpose of such a dirigible is open to speculation, although it is important to note that China is the fourth largest country in the world (slightly smaller than Canada), with large mountain ranges and remote regions bereft of surface communications. Obviously, any airship could equally be used for military surveillance, early warning, and/or logistics. Little has publicly been made available, although a China observer has found information on some of their aerostats (tethered or stationary airships).

Herein we take another look to the skies, this time to the modern reincarnations of airships. A number of companies worldwide are spending hundreds of millions reinventing dirigibles with modern materials and technologies, to make them larger, safer, more manoeuvrable, and capable of landing in unprepared areas.

The solution for the future of remote transportation could lie in an older technology that is gaining renewed interest. In the inter-war years, large airships carried dozens of passengers at 80 miles per hour, crossing the Atlantic on regularly scheduled flights. Investment in airships was curtailed by the rapid development of airplane technology during World War 2. With cheap oil after the war, everyone wanted to go fast, and airplanes had an acceptable safety record.

With numerous recent innovations in structure, shape, and ballasting, we are now seeing a number of rigid, semi-rigid, and non-rigid airship prototypes being designed, tested, and flown. With new technologies and advances in composite materials, sophisticated flight controls, solar panels, and electric motors, modern airships will be safer and more manoeuvrable. As well as requiring far fewer ground crew than their previous generation cousins. The race is now on to complete and flight test passenger and transport airships.

This writer attended the Aviation Innovations Airship Conference on October 21-22, 2022 in Toronto, Canada to find out the lay of the land, as it were. Why was it held in Toronto? Canada is a vast country, second largest in the world, with many mineral mines and remote communities in its northern territories. So many mines, that the world hub for mining company headquarters is in Toronto. And there are a number of provinces, territories, and companies in Canada that are seeking a cheaper, more sustainable way to transport freight and passengers to and from remote northern regions.

A number of other countries also believe there is an opportunity and a market for lighter than air vehicles to transport freight, people, and emergency assistance to sparsely settled regions with minimal infrastructure.

Aviation’s pollution problem

Aviation is one of the last transport sectors exclusively using fossil fuels. As a result, aeroplanes are the most polluting form of passenger and freight transport. Aeroplane weight and space are critical factors, which have made the use of batteries and hydrogen fuel cells unfeasible to date.

Large capacity electric cargo and passenger commercial aeroplanes are still at least a decade away. Unfortunately, much of the aviation industry’s work to reduce its Greenhouse Gas (GHG) emissions are public relations efforts with questionable and misleading carbon credits. Climate change is becoming an increasing concern, and the aviation industry is increasingly coming under the spotlight for its highly refined fuel use. Modern airships provide an alternative.

We have previously looked at the Imperial Airship Service, Britain’s 1920s plan to communicate with its Commonwealth around the globe much quicker than steamship. This scheme did produce a cross-Atlantic flight of the R.100, but the Service was cancelled when it’s sister ship R.101 crashed and burnt in France with only six survivors the following year.

However, hydrogen lifting gas was not the only Achilles heel of first-generation airships. Even the US Navy, which flew the only helium-filled airships of the period, had its share of airship disasters. Flying into separate storms, the airships USS Macon and USS Akron crashed with large losses of life. This spelt the end of the US rigid airship program, although they continued with non-rigid surveillance blimps for a few decades.

Back to the Future

Nonetheless, there are parallels in aviation between the interwar period and today. There were advancements in aerodynamics and lightweight structures in both eras. Aeroplanes cover long distances quickly, but at great cost in fuel and to the environment. Furthermore, they require long airstrips, which are expensive to build and maintain. Many remote areas don’t even have an airstrip.

Hybrid airships are about 20 to 40 percent heavier than air, to better ‘stick’ on the ground without the need for a mast or large ground crew to moor the ship. The advantage of this design is their ability to unload cargo, return empty, and not be overly buoyant. They take off with vectored engine thrust and produce extra lift with their aerodynamic hull shape. The corresponding disadvantage is the higher fuel burn required to carry the same payload as a more traditional airship design.

Whilst airships do not require much in operational infrastructure, they do require hangars (airdocks in airship industry parlance) for construction and maintenance. Airdocks operate more like drydocks than airports, as airships need weather protection for 10 to 14 days per year for annual inspections and major overhauls. Otherwise airships operate like ships, moving from port to port.

Lots of space, long range, and no need for runways

We may soon no longer be prisoners of geography and airports. Due to the noise and pollution that jets produce, airports are almost always many kilometres from the cities they serve, and require dozens of square kilometres of flat land, usually farmland.

Airships, being whisper quiet in comparison and much less polluting, can land much closer to the they cities travel to. Even closed lakeside airports would be ideal city airship landing spots.

Generations of Airships

• First Generation: The Classic Era, 1900 – 1937.
• Second Generation:1940 – 1962. US Navy blimps for naval and submarine reconnaissance.
• Third Generation: 1963 – 1999. Small Goodyear advertising blimps and Zeppelin touring airships operated.
• Fourth Generation: 2000 – Present. Prototype airship designs.

Disaster relief, humanitarian aid, border and military surveillance are all prospective uses for modern airships. But it is likely the global demand for rare minerals, and military uses, that will drive airship innovation.

Rare Earth metals

China is the leading extractor of rare earth metals, which are increasingly used in advanced batteries for use in electric vehicles and trains. However, geopolitical tensions may cut off this supply.

Other countries have suspected reserves of such metals, but their remote locations impose overwhelming logistic penalties. Hence this restricts exploration, so the true extent of such reserves are not known. Specifically, geophysical survey equipment is large and heavy, larger than drones can carry. Transporting mining equipment and physical plant is energy intensive, often requiring large helicopters to bring it in. The limiting factor in bringing in equipment is the size of the truck tires – everything else can be disassembled to smaller components. Furthermore, extraction and logistics are often too expensive to make mining cost-effective. Airships provide a much better transport option for such equipment.

If you can make it in the Arctic, you can make it anywhere

Many countries have remote regions, with challenging geography and long distances. Often such regions have mineral deposits that could meet world demands for metals used in vehicle and battery manufacture. The primary challenge is the cost of extraction. Canada’s Arctic provides an excellent case study and test conditions for the airship transport mode.

The price of virtually everything in remote communities is two and a half to three times more expensive than in developed areas. This has meant an under-developed hinterland that impedes private investment. This territory is where the emerging generation of airships could fill gaps in the existing transportation networks.

Airship transportation has three drivers in its favour:

• Fuel prices
• Environmental concerns, often in a more easily disrupted ecosystem
• The need to serve locations without established infrastructure and technological advances

Ice Roads

As seen on the popular Ice Truckers television show, ice roads are plowed on river and lake ice thick enough to support 18 wheel transport trucks. Unfortunately, global warming is reducing winter ice thickness, making such roads unreliable or non-viable for more of each winter. Construction of all-weather gravel roads is prohibitively expensive on muskeg, permafrost, and over many water crossings. Recent northern road construction cost about $3M per km, depending on the number of bridges required, rock outcrops to blast, and swamps to fill in.

Pioneering a new ice road is much more expensive. Even then, truck shipments are 65 to 70 percent more expensive than over all-weather roads, as trucks have to travel more slowly crossing frozen lakes. Ice roads usually open in January and close in March. The length of the ice road season depends on location and weather, then melt away in spring. In a severe year like the El Niño of 1998, ice roads were not possible at all, and much more expensive air transport was the only option.

Arctic Airship Weather Testing

The ISO Polar Airship Association, the not-for-profit organizer of the Airship Innovation Conference, is exploring the development of a cold weather research and testing facility at Thompson, Manitoba. This town is already well-established as a cold weather testing location for cars, trucks, snowmobiles, and jet engines. What’s more, Thompson has a unique infrastructure opportunity for airships – there are several trench-shaped open pit, but abandoned, nickel mines that could house the largest airships being contemplated. Efforts are underway to finance a feasibility study to repurpose these sites for airship development and production testing. A Thompson Trench could also be used for airship inspection or major repair.

Potential airship cold weather research & testing trenches in Thomson, Canada. ISO Polar Airship Association

Existing Arctic airfields are also being threatened as the permafrost melts below it. Electric airships could be an ideal, sustainable solution – no need for airfields or polluting fossil fuels. The windswept Arctic could be as an attractive to wind turbines as Scotland in providing local electricity. Whilst Arctic winds do not usually shift a lot, they can at times blow hard, lasting several days, and during this time most other aeroplanes cannot fly either. Wind turbines are much more sustainable than transporting in aviation fuel to store in giant tanks.

Long supply chains by air to small communities can mean that a litre of milk costs over three times more than in more populated areas. Thus, poverty, food insecurity, and sub-standard housing plague many remote settlements. Year-round cargo airship service would greatly improve remote economies and communities, making them better, more resilient, and attractive to investment.

Airship infrastructure

There are currently approximately ten airdocks in the world, most having been built for the first generation of airships in the previous century (this list does not include the large structure in China mentioned at the beginning of this article). Without more airdocks, the airship industry cannot grow. Aeroplane hangars are not sufficiently tall for airship use.

Modern airships have vastly improved VTOL (vertical take-off and landing) and ground manoeuvrability over the previous pre-war generation, which had fixed engines, usually with forward thrust only, occasionally with reverse. Widespread airship use would avoid expansion and extensive use of land consuming and heavily subsidised airports.

Military and surveillance uses

Airships are also being developed by the US military for surveillance, along with high altitude blimps. Airships actually use a minimum of material – lightweight frame components – wrapped in modern fibres, with lightweight fibreglass and composite cabin and components, so despite their large size, airships actually have quite a small radar cross-section.

In the civilian sector, similar surveillance uses are being developed to monitor remote areas for methane and other oil & gas industry emissions, industrial pollution, wildfire threats, as well as providing internet connectivity.

Helium, the second most plentiful gas in the universe – but not on Earth

Helium is not frequently found in nature, so is generally considered a non-renewing resource. It had been used for party balloons, and raising people’s voices a few octaves. However, with increasing medical, scientific, and micro-electronics production uses of helium, entertainment uses of the gas have been curtailed.

Helium is used in MRIs, nuclear magnetic resonance, and pharmaceutical development, among other applications – the crucial semiconductor industry uses a lot of helium. To chemistry research scientists, liquid helium is like liquid gold – it is the coldest substance on the planet. Helium also keeps super-conducting magnets operating. NASA uses helium to separate fuels in rockets, and the US Defense Department requires the gas for its radiation-detecting sensors.

There are only a few locations in the world that are reliable sources of helium: the US, Qatar, and Algeria. However, because the gas is so light, it is difficult to trap and store. It is occasionally found trapped in rock formations, but the majority is extracted from helium rich natural gas deposits, which is definitely not green. This ‘rich’ is relative – the concentrations are only 0.04-0.35%. As a result, it is not possible to increase production significantly to meet new demand.

Unfortunately, the US is exiting its traditional role in safeguarding helium, after Congress passed a law in 2021 for the US government to sell off its helium reserves. This has led to a vast rise in the cost of helium, now around $400 US/thousand cubic feet. For a ship like the Airlander 10, which uses 38,000 cubic meters of helium (1,342 thousand cubic feet), which is about $536,783 US. There are reports of a new helium field in Tanzania, but it is not of sufficient size to affect commercial prices.

The return of hydrogen as a lifting gas?!?

Some airship manufacturers would prefer to use hydrogen as the lifting gas, if it be approved by the FAA. Obviously, they and any other aviation safety authority would need to be convinced of its safe use aboard dirigibles. It is worth noting that hydrogen only gives 8% more gross lift than helium. Rigid airships are about 50% deadweight, so this works out to 16% more cargo lift. This is not inconsequential because it is a pure profit – all other costs are same.

A number of companies are researching ways of developing ‘safe hydrogen’ lifting gas, as hydrogen is much easier to produce and cheaper than helium. Essentially, this means diluting the hydrogen to make it less flammable. A hydrogen and helium mix has been tried, but it is not yet clear if it is completely safe. Some companies are researching adding other gases to render hydrogen less flammable.

Hydrogen, however, has many of the same problems as helium. They are the two smallest molecules, so are difficult to contain without leaking. Green hydrogen also requires more expensive sustainable energy to power the electrolysis. Although powered by wind turbines and/or solar panels in remote locations, this could be workable.

Finally, insurance companies would need to be convinced that hydrogen airships would be safe. Even so, premiums would be more expensive than helium filled dirigibles, where you could find a company to actually insure one.

NASA’s Technology Readiness Levels (TRLs)

Is it often helpful to gauge the technological maturity of new technologies by applying NASA’s Technology Readiness Levels (TRLs). The scale is 1 to 9, wherein 1 is the concept stage, and 9 is operational.

1. Basic principles observed and reported.
2. Technology concept and/or application formulated.
3. Analytical and experimental critical function and/or characteristic proof of concept.
4. Component and/or breadboard validation in laboratory environment.
5. Component and/or breadboard validation in relevant environment.
6. System/sub-system model or prototype demonstration in an operational environment.
7. System prototype demonstration in an operational environment.
8. Actual system completed and qualified through test and demonstration, for its intended operational environment and platform.
9. Actual system proven through successful operations.

For example, hydrogen fuel cells are TRL 8 or 9, but still need to be proven to be commercially and sustainably acceptable throughout the support chain (clean production of hydrogen, safe hydrogen distribution networks, safe leak limited storage tanks, &c).

Airships presented at this Conference are at different technological readiness, which I assign a level based on the extended NASA TRL Definitions.

A flight of airship companies

There are a number of companies designing and testing modern airships. All will use helium, at least initially. Here are the companies furthest along in development:

Zeppelin – Germany

This is the company most associated with airships. What is much less known is that the company still exists, and still builds semi-rigid touring airships. The Zeppelin ZF Company developed the Zeppelin NT07 semi-rigid airship in the 1990s. Its two main engines can swivel to push the airship up or down, with a third aft engine driving a pusher propeller that can rotate down 90 degrees to assist with takeoffs and for slow speed control. A few companies use these ships to fly passengers on scenic airborne tours of German and Austrian cities, and the countryside.

Seven Zeppelin NT07s have been constructed since 2000, but they have not been a commercial success, due to high capital and operating costs, and a small passenger load of 12 limiting their appeal. Nevertheless, the Goodyear Company in the US has retired its traditional fleet of blimps and purchased three Zeppelins to replace them. The company wants to develop a more modern 15 tonne Zeppelin as a 19 passenger proof of concept ship.

It is important to note that only blimps and semi-rigid airships (like the Zeppelin NT) have been certified for commercial use to date.

Hybrid Air Vehicles – UK

George Land of Hybrid Air Vehicles (HAV) virtually presented progress on the Airlander 10 at this conference. Helium is primary source of lift, with thrust vectoring from her four engines as its second source. HAV has gone with a catamaran dual gasbag non-rigid design, which shapes the ship’s envelope as an airfoil, which is its third lift source once moving forward. The term ‘hybrid’ in an airship context means that the lift comes from a number of sources.

One potential Airlander 10 passenger cabin configuration. HAV

The Airlander design started as a US Department of Defense Long Endurance Multi-Intelligence Vehicle reconnaissance platform design contract, called HAV 304. She first flew in 2012, but the program was cancelled shortly thereafter. Hybrid Air Vehicles purchased the demilitarised ship and brought her to Cardington, UK, where the company refined her design, becoming the Airlander 10. Her maiden UK flight took place in August 2016. Unfortunately, she attempted too steep a landing during a 2017 test flight, and was damaged.

The path to certification needs to be developed

Nonetheless, HAV continued design work and in 2018, the European Aviation Safety Agency (EASA) awarded Hybrid Air Vehicles Ltd a Design Organisation Approval and a Production Organisation Approval. Then in March 2022, in collaboration with HAV and other European buoyant aircraft manufacturers, EASA released the base requirements to certify airship designs.

As in the US, there were no European certification standards for rigid airships. These new EASA standards allow HAV to work towards a Type Certification to certify the Airlander 10’s airworthiness, which is required to start production. Whilst this typically takes between three and five years, depending on the size and role of the aircraft, HAV has already completed much flight testing in close communication with EASA. As a result, HAV anticipates that Airlander 10s will enter service in 2026.

HAV expects concurrent UK Civil Aviation Authority (CAA) and US Federal Aviation Authority (FAA) certifications, once EASA certifies. These agencies coordinate their work to a degree, but retain the right to set specific requirements.

A reservation for ten Airlander 10s was made by Spanish airline Air Nostrum in June 2022, worth £485M. Each airship will be configured for 100 passengers, to begin operation in 2026. This video shows the rendering of the passenger space. HAV foresees its prime market as higher end experiential travel, taking tourists to remote locations where there is no prepared landing surface. With a 2,000 mile range, Airlanders could also serve as a luxury ferry, rather than directly compete with aircraft.

In November 2022, HAV announced a study to explore the case for using Airlander 10 aircraft for passenger transport and freight in the Scottish Highlands and Islands. It is expected that the study will investigate how Airlander 10 would improve connectivity for communities across the region sustainably, where air travel is a lifeline. The freighter configuration would be able to carry 10 tonnes.

HAV is also working with the University of Sheffield’s Advanced Manufacturing Research Centre to build a production factory in that area, drawn by the high skill base. Production Airlander 10s will also have water landing capability for maximum utility.

Variants under design

• An all-electric Airlander variant for zero-carbon emissions, to be operational by 2030. HAV has been working with Collins Aerospace, University of Nottingham, & other companies on all electric power trains.
• A larger 50 tonne Airlander 50 freighter to carry twenty foot shipping containers, with a rear ramp to provide easy loading and unloading.
• Airlander 50 Combi, to carry six 20 foot containers, and around 48 passengers.
• The Airlander 200 is planned to carry 200 tonnes of freight.

Nevertheless, HAV is also designing in capability for military applications. The Ukraine War is demonstrating need for long duration standoff aerial surveillance. A similar performance specification applies for anti-terrorism monitoring.

The Airlander 10 has short and vertical takeoff and landing options, and can hover – which is important for carrying outsize loads such as large pylons or turbine blades. This avoids the need to build expensive roads to remote areas.

HAV is working with airlines to design specifications and layout, ie size, passenger layout and amenities, and payload.

Technology Readiness Level

The UK’s Hybrid Air Vehicles has taken the early lead on putting a modern airship into service, and appears to be the front runner to have the first certified modern airship. The Airlander 10 has already logged hundreds of flight hours, and dozens of take offs and landings.

The Airlander 10 is TRL 5: Aircraft validation in desired environment has commenced.

LTA Research – USA

This Google spinoff company was founded in 2015 to develop next generation airships. It is backed by Google co-founder Sergey Brin, whomst has long been an aviation enthusiast and is the impetus behind this company.

Briton Alan Weston spoke at the Conference about the company’s Pathfinder design. He has been involved with the company since its beginning. A keen hang glider pilot, he took inspiration from their use of lightweight yet strong carbon-fibre tubes. Applying this technology for LTA’s Pathfinder 1 prototype airship’s internal structure, as well as titanium joints, has saved considerable weight. This dirigible is designed with solar panels on top to power their electric motors and three rudder fins.

Pathfinder 1 is being designed to help transport humanitarian aid to remote disaster sites, carrying both cargo and passengers, whilst reducing the carbon emissions. She is 400 feet long (larger than the Airlander 10), and is designed to lift 28 tons at 60 knots with a 2,800 miles (4,500km) range. She is being built and tested in the old US Navy blimp shed at Moffett Field in Mountain View, California. Here is Alan Weston showing the Pathfinder 1 features.

Pathfinder 1’s electric motors will initially be powered by batteries, but the company hopes to later replace them with what would be the world’s largest hydrogen fuel cell. This will be much lighter than batteries.

Construction of Pathfinder 3, which is planned to be 600ft long with a payload of 35 tons, has not yet started at the Airdock in Akron, Ohio, a 1,000 feet long airship shed. This shed dates from the US Navy’s evaluation of airships in the 1920s. She will be the biggest airship constructed in the US since 1931, when Goodyear designed and built the 785 foot long sisters USS Macon and USS Akron for the US Navy. Having a larger payload, Pathfinder 3 is primarilydesigned as a freighter.

The company has constructed scale model airships to test design concepts and the flight software avionics. The company describes a number of other technical innovations, plus the use of components and designers’ expertise from the Zeppelin ZF Company,

LTA Research is also working concurrently with the Federal Aviation Administration (FAA) on developing rigid airship certification requirements – as existing requirements only cover non-rigid blimps, which have been flying for decades. However, LTA’s Weston did not comment on any detailed development timelines, costs to date, nor total budget.

Construction of Pathfinder 1 is complete and she has taken her first indoor flight in her airdock on 14 June 2023 to test basic flight functions. Her first open air test flight is planned for later in 2023.

Innovative construction

LTA Research’s airships will use helium and a frame made up of 3D printed girders, carbon fibre reinforced polymer tubes, and titanium joints. These are assembled in a modular design on a large jig that rotates the airframe whilst under construction, which allows for rapid construction. And it avoids having workers climbs tall ladders to assemble parts onto the hull.

Technology Readiness Level

The level for the Pathfinder 1 is TRL 4: Aircraft validation in laboratory environment (within the Airdock).

Flying Whales – France

This French company started in 2012 as a potential solution to resolve a lumber extraction bottleneck. Helicopters are currently used to lift logs out of difficult and remote terrain, but it is a slow and expensive process.

The company developed a 60 tonne airship design, and a belly cargo with winches, able to transport long logs, wind turbine blades, as well as standard shipping containers. Even French rocket component transport to their Pacific launch site.

Flying Whales forecasts a global need for more than 100 such ships, as they have noted a 30% reduction in winter road access over last 15 years. In addition, wind turbine blades are getting larger for greater efficiency, but that is making their road transport increasingly difficult. Furthermore, wind turbine farms are being located in more remote locations due to NIMBY spurious health scare concerns.

The company is putting its prototype LCA60T dirigible (the French word for steerable balloon) through subsystem, ground, and tethered flight tests. She has seven pivoting engines to provide vertical take-off and landing (VTOL) capabilities.

Construction of the initial assembly line north of Bordeau is underway. Flying Whales is planning to build a second factory in Québec to construct airships for North and South America. And they are scouting third assembly line location in the Far East for those markets.

The Québec government has invested $55m in the company, as the province has a vast northern territory with abundant timber and mineral reserves. The Québec subsidiary is called Les baleines volantes.

The French company is also designing a Flying Care modular hospital to fit in the cargo hold, to bring modern healthcare technology to remote communities.

Flying Whale airship winching standard cargo containers into her belly

On 5 January 2023, Flying Whales announced a Letter of Intent with aerospace rocket company ArianeGroup to study the potential of using the planned LCA60T airship to transport of Ariane 6 spacecraft components. ArianeGroup has European sites, and a Space Centre at Kourou, French Guiana, (Guyane française, an overseas French département) that is far from the ocean port of Pariacabo. As this is currently a treacherous land journey, the space company plans to transport launcher components in containers, as well as rocket stages and fairings. A key factor in this signing was to minimise the environmental footprint of such transport, whilst providing access to areas without sufficient road infrastructure to transport large components.

This agreement comes after a partnership was signed in 2022 with Guyana, which wishes to use airships to transport logs and building materials from one end of its territory to the other.

Rapid ballast system are needed to maintain equilibrium during unloading and loading. Helium compression has required more than a decade to develop and refine, yet this technology is not quite ready for commercialisation.

First flight is planned for 2025, EASA certification first, then certification for Transport Canada. Québec operations are projected to start in 2027.

Technology Readiness Level

The estimated level is TRL 4: Component/subsystem validation in laboratory environment.

Buoyant Aircraft Systems International (BASI) – Canada

Buoyant Aircraft Systems International (BASI) plans to land its rigid airships on a modified turntable, the Buoyant Aircraft Rotating Deck (BARD).

Buoyant Aircraft Rotating Deck (BARD). BASI

Technology Readiness Level

This level is TRL 2: Technology concept and application formulated in applied research.

Lockheed Martin – USA

Dr Robert Boyd, Program Manager of LM Aeronautics, Lockheed’s airship division, spoke at the Conference. Appropriately, and unfortunately, he couldn’t talk about any of the company’s ongoing dirigible projects, as they are being developed for the US Department of Defence. Part of this may be because Skunk Works, Lockheed’s historic group that develops advanced aircraft, worked on an airship design for more than 20 years. It last flew a subscale prototype in 2006.

In 2013, Lockheed Martin started promoting the LMH-1 as their large commercial hybrid airship, based on their previous P-791 design. The LMH-1 would generate about 80% of its lift from the helium buoyancy, with the balance from the vectored thrust engines and from aerodynamic lift generated by the lifting-body fuselage in forward flight. It is obvious from the renders of this design that it was the predecessor of the HAV Airlander 10.

LMH-1 render, shewing straight stern, without the Airlander ‘bum’. Lockheed Martin

This design had a crew of 2, with up to 19 passengers, carrying a payload 21 metric tons of cargo at 60 knots (111 kph) a range of 2,593 km (1,400 nautical miles). The cargo compartment was a little bigger than the cargo box of Lockheed’s C-130 Hercules short take-off and landing (STOL) medium-sized air force transport, with the same payload (20 tonnes), but of course not needing an airstrip to land. It features an Air Cushion Landing System (ACLS), using hovercraft technology to safely land the craft and move around on varied terrain. Lockheed envisioned its main market as cargo transport into remote areas.

This design had been undergoing an iterative FAA certification process for several years. However, Lockheed Martin’s Dr Boyd would neither confirm nor deny any information on the progress in certification, nor any other details.

What is known about the company’s planned dirigibles:

• LMH-1 20 ton capacity airship, which Lockheed is no longer marketing
• LMH-2 90 ton 3,000+ mile range proposed airship, scaled up version of the LMH-1
• LMH-3 500ton 6,000+ mile global range proposed airship, scaled up version of the LMH-1

Lockheed Martin has not actively marketed its LMH-1 airship for several years now.

Technology Readiness Level

From the published information, we estimate LMH-1 to be TRL 4: Aircraft validation in laboratory environment (within the Airdock).

LMH-1 & its intellectual property spunoff to a new company

On 9 May 2023, Lockheed Martin transitioned its airship business to a newly formed company AT² Aerospace. This company’s Z1 design appears to be very similar to Lockheed’s LMH-1. In addition, Dr Robert Boyd has left Lockheed Martin to become President and Chief Operating Officer of the new company. A month later, Straightline Aviation signed a Letter of Intent with AT² Aerospace.

Current issues with airships

Instead of discussing Lockheed Martin’s airships, Dr Boyd discussed the main technological challenges that all airship designers face:

Buoyancy/Mass Balance

This is the toughest problem for airships – it is difficult if not impossible to turn off their natural buoyancy. Ballasting is the main solution, it is simple but inelegant, typically requiring 60-100 tons of water. But pumping water aboard takes time, and may not be available in all landing locations. In addition, time on the ground to pump water costs flying revenue.

An alternative is a ballonet, which is an air bladder inside the airship envelope – when air is pumped into the ballonet, this increases the density of the lifting gas, thereby decreasing its lift.

Knowing this buoyancy/mass ratio during flight is critical to optimise operations.

Environment

Wind is the biggest worry. Ninety percent of blimp and airship accidents occur entering or exiting a hangar, because of the swirling wind. In general, the key is to move to avoid the heavy winds as much as possible, as aeroplanes and ships do. Tornados and swirling winds are particularly difficult for airships, as winds rapidly switching directions cause more damaging than direct intensity. Most of the time, however, with increasing windspeed comes decreasing probability of direction switching. A strong weather front can change wind direction quickly, but fortunately this can be avoided with weather radar.

Rainwater adds weight and can permeate the envelope, potentially adding hundreds of pounds and making the controls sluggish. Fortunately, ice on airships is not nearly as critical as ice on aeroplane wings. Furthermore, the air filled ballonets inside the envelope condense water, which grow mold and spores.

Lightning is not an issue as airship envelopes are dielectric, shielding everything within. However, all wires and electronics outside the envelope and cabin do need to be hardened.

Airships can still go tail up at a mast in about 20 seconds under certain weather and wind conditions – as being near neutral buoyancy leads to an unstable flight attitude.

USS Los Angeles tail up

Maintenance

Envelope maintenance and repairs (internal and external) can be quite difficult, as the ships are tall and curved, and tend to move around easily when outdoors. They require high lifts or cranes. Design for ease of maintenance is critical. Lockheed Martin has developed small robots that crawl the outer envelope, like Roombas, that find and repair envelope tears automatically. Internally, the airship frame needs to be designed to allow manual access to the gas bags and ballonets, as well as to the structure.

Anumá Aerospace – US

This US company is taking quite a different approach to the lifting gas. Namely, to use air. More specifically, the lack thereof – vacuum lift. CTO James Little describes their airship design as operating like a submarine in an ocean of air.

However, to construct a sufficiently large vacuum vessel to provide significant lift is not as simple as it appears. Compressive loads require large amounts of mass, such as submarines or deep sea diving bathyscaphes.

Anumá Aerospace is designing an airship using only vacuum spheres for lift. This would make much longer flights possible, by onboard pumps evacuating air as needed. No use of, or loss of, expensive gas. Just pumping air out – or letting a bit in to descend. Flight time will depend only on in-flight solar energy harvesting.

The Anumá spheres use a tensigrity (the portmanteau of tensile and integrity) structural system to transfer compression to tension loads. Tensigrity is a system of isolated components under compression, inside a network of continuous tension. The compressed members (usually bars or struts) do not touch each other, whilst the pre-stressed tensioned members (usually cables or tendons) keep the spatial stability. The term was coined by Buckminster Fuller in the 1960s.

Benefits

The benefits of vacuum lift are many – as no lifting gas is necessary, no expensive helium would be needed, nor dangerous hydrogen. And no emissions from producing, transporting, or storing any gas, greatly simplifying support logistics.

Furthermore, helium has small atoms that permeate out of any container – hence the longest that a helium balloon has been aloft has been two months. Vacuum lift provides conceivably infinite duration aloft, if powered by solar panels and electric motors. Requiring no fuel to stay aloft means more lift for carrying a payload. With simplicity also comes reduced maintenance time and cost.

Design

Anumá started with a small, 3D-printed, carbon-fibre-reinforced polymer test sphere. A sphere has the lowest surface area to volume ratio of any 3-dimensional shape, due to the square-cube law – the surface area of a sphere increases by the square of the radius, but the volume increases by the cube of the radius. A sphere is also the strongest 3-dimensional shape, making it the ideal for vacuum lift cells.

Tensigrity ball

The company is currently prototyping a 12m (37 ft) diameter sphere, which is the size of a hot air balloon. It as a geodesic approximation of a sphere, covered with a multi-layer carbon fibre membrane system, from which air is evacuated with air pumps. The first goal is to achieve an internal pressure equal to 30% of mean sea level (MSL) pressure (30,398 Pascals (Pa), or about 30 kPa). For perspective, mean sea level pressure is 101,325 Pa or 101 kPa.

Once aerostatic lift is demonstrated at 30% MSL, the next step is to advance the technology to achieve 15% MSL (85% vacuum), to attain the density of helium. Then work will proceed on incremental improvement with the goal of reaching 7% MSL (93% vacuum) to approximate the lift of hydrogen.

A failure of a lift sphere will most likely be a slow leak in the membrane, which can be counter-acted by running the pump, and making a slow, safe descent to land if necessary.

The company plans to steer their airships by pumping air in or out of the spheres to ascend or descend to catch winds of a different direction. The paper Using the jet stream for sustainable airship and balloon transportation of cargo and hydrogen describes the science and the potential.

Hadley Cells global wind patterns

The internal design of the Anumá airship will be like bathyscaphes, a series of spheres connected together. Much like the Cetacean submarine from Man from Atlantis television series, but within a streamlined envelope, to fly as aerodynamically efficient as possible:

Cetacean submarine from Man from Atlantis television series.

The difference in air pressure is greatest at ground level, which is the point of greatest stress for a compressive system.

Technology Readiness Level

Based on my interview with Anumá, I estimate their level to be TRL 3: Analytical and experimental proof of concept validation of critical functions.

Whilst this technology is less advanced than others presented at this conference, it might have greater long term promise – simple, cost-effective, with a much smaller fuel supply chain than conventional dirigibles.

General Airship Design Considerations

• Airship efficiency improves with size. Like volume purchases in a store, there is less envelope per unit of lifting volume as size increases.
• It is best to have as many ground interface devices on board, to minimise landing zone infrastructure and crew required.
• Whilst experiential passenger travel generally flies only in good weather, freight operations need to fly in all seasons and conditions.
• Current production airship costs, of the sizes discussed at this conference, are expected to be in the $80-90M US range.

Other Airship Development

Companies in Brazil, China, and other large countries are also in the airship development game, but were not evident at this conference. However, this table shows their progress:

Country	Company	Structure	Status	Payload
Brazil	Airship do Brasil	semi-rigid cigar	engineered design	30 tons
Argentina	AeroVehicles Inc.	semi-rigid catamaran	concept design	20-40 tons
UK/France	Varialifter	rigid cigar	concept design	50-250 tons
US	Worldwide Aeros	rigid hybrid	Prototype built, now disassembled	66 tons

The lay of the airspace

Whilst there are some well funded players in this airspace – Lockheed Martin, LTA Research – there are many other companies are funding millions research and development on different aspects of lighter than air flight. Despite the use of off the shelf motors, components, and materials, the flight dynamics of airships are unique. Dirigible flight management software will need to be progressively tested and improved to handle all manner of environmental and weather conditions, unique to each airship design. As the state of the art data is shared, the industry learns and grows.

Most governments are wary of investing in new civilian technologies, having been burnt in the past. Military needs generally receive much more funding – at least until a better option appears on the horizon. Many militaries are also keen on lighter-than-air vehicles for long duration surveillance operations. Some companies have developed or are developing military airships, and they have not been making their progress public.

Airship efficiency is key for commercial success

Airships use less energy to move per tonne-kilometer thanks to their natural buoyancy. Cost per tonne or passenger km is vital to progress to affordably low production expenditures. The late 1920s Hindenburg Zeppelin design was on the cusp of that, after the success of the commercially too small Graf Zeppelin I.

For passenger uses, airship capacity could be compared with a ferry or small cruising vessel, if proposed for inter-island or island-mainland services.

Freight payloads could be measured in equivalent HGV lorries, for example how many gross 40-50 tonne HGV payloads (28-35 tonnes deadweight) could be carried in equivalent time by an airship. This would enable comparisons with replacement (or supplementation) of lorries on ferries by an airship. It is the comparative delivery volumes and times which will matter on a route-by-route basis. So far, no one appears to have looked at comparative economics.

Prize money is coming – Airship Sky Race

The World Air League has announced its World Sky Race for 2024-2025, an epic race of green airships around the world. It is to encourage more sustainable airship designs, and is inspired and led by the organisers of the Tour de France. The plan is to start at Greenwich, fly over London, Berlin, Rome, and 15 other Summit Cities, overflying 2 billion people in 16 stages, with a Sky Cup for each stage, like the Yellow Jersey.

It is based on successful transportation technology development prizes:

• The UK’s Longitude Prize in 1714, which stimulated the development of the first practical navigational device to determine a ship’s longitude.
• The Orteig Prize, which inspired Charles Lindbergh to fly from New York to Paris nonstop in 1927, which greatly expanded interest in air travel.
• The Coupe d’Aviation Maritime Jacques Schneider, also known as the Schneider Trophy, was a prize awarded to the winner of a race for seaplanesto encourage technical advances in civil aviation, and was significant in advancing aeroplane design.
• The contemporary XPrize has fueled competition to make commercial space rockets more practical.

The World Sky Race Prize of $5M will be awarded to the winning airship team.

A potentially leapfrogging technology

Increasing globalisation is accelerating economic development in Africa and other infrastructure-poor regions. Airships can provide a technological and cost-effective leapfrog over airports, roads, and railways, much as mobile phones have proliferated in poor countries with limited telecoms landline infrastructure.

Many thanks to Dr Barry Prentice, President of the ISO Polar Airship Association and Buoyant Aircraft Systems International for access to this conference, and for providing key insights.