Empire of the sky: The Imperial Airship Service

London 2026 AD this is all in the air, by Montague B Black, 1926

The artist Montague Black was famous for his work for the White Star Line shipping company. In 1926 he created a new piece of art for London Underground, a painting set a century in the then future. His vision of 2026 was a city dominated by two things: the aeroplane and the ‘Overground Line.’ This may seem prescient, but Black’s ‘Overground’ was not one of trains, but by a far more remarkable form of passenger transport – airships.

By Long Branch Mike

Black’s painting isn’t the only reminder of London (and indeed Britain’s) airship past. A physical one can be found at Cardington, a village just outside Bedford within the London commuter belt. There, two massive airship sheds still stand. Today they play host to a new British airship, the Airlander 10. The sheds were originally assembled for an even grander scheme, to connect London to its Dominions – the Imperial Airship Service, which promised not just to cut ocean crossing times by a half to a third, but also to do so with a degree of grace and ease that few steamships could match.

Britain is late to the party

Britain came late to the airship game, only developing larger rigid dirigibles after London had been bombed by Zeppelins, starting in May 1915. Those attacks highlighted just how effective airships could be and with the threat of even larger Zeppelins on the horizon, the UK Government decided to accelerate its own development plans.

This was not to say that there hadn’t been British efforts in this area before the First World War. Small airships funded by wealthy individuals had been built in earlier days and in 1909 Flight Magazine ran an ‘Airships for the Nation’ campaign and some supportive government funding emerged. Even at this stage this was largely a reaction to German efforts in this area, led by Graf von Zeppelin.

It was ultimately the war though that pushed British airship development forward and by the Armistice, the Royal Naval Air Service (RNAS) operated 103 dirigibles, albeit all smaller than their rival Zeppelins. Most had a semi-rigid design rather than the robust German fully-rigid design, which had airbags enclosed in a metal frame (known as a ‘hull’).

Vast distances by airship

One of the main attractions of airships during the war for Germany, Britain, France and Italy had been range. This was epitomised by L 59 (Zeppelin works number LZ.104) which undertook the longest airship flight of the whole war. Departing from Bulgaria with critical war items in 1917, it was intended to resupply General von Lettow-Vorbeck in German East Africa, one of Germany’s (if not the war’s) most creative and successful commanders.1 It flew non-stop over the Mediterranean, the Sahara and part of British-controlled Africa, only turning back when it received word that the General had been forced to cede the Zeppelin-friendly flatlands of the colony to the British and withdraw to the mountains.

Von Lettow-Vorbeck pinned down over 300,000 allied soldiers in Africa for four years with a force that at its largest comprised only 14,000 men. He returned, undefeated, to a hero’s welcome in Germany after the armistice. A noted anti-racist, when offered the role of Ambassador to Britain in the thirties by Adolf Hitler, the General infamously told the Fuhrer to ‘go fuck himself.’

By the end of its unplanned return flight L 59 had flown a total distance of 4,199 miles in 95 hours, a world record 99 years ago and one that remains impressive even now. No commercial airplane could stay aloft that length of time in 2016, except with multiple repeat episodes of in-flight re-fuelling. By comparison the Zeppelin did it with only one extended-range load of fuel. This range was useful in wartime, but was equally useful when peace came, and it was not long before airships were being seen as a possible option for getting from London (and the rest of Europe) to America.

Atlantic adventures

The British R.34 (a derivative of the wartime Zeppelin designs, particularly the LZ.76) flew to New York and back in 1919, a voyage plagued by adverse winds. A Zeppelin (works number LZ.126) was built by Germany for the USA as war reparations and was also flown across the Atlantic in 1924 and giving its name to a popular fox-trot dance song at the time ‘On the ZR-3’. It also carried mail – a valuable revenue earner.

ZR-3 “USS Los Angeles” moored to a USS Pakota in 1931


By the 1920s the potential for these colossal vessels to become profitable peacetime long-distance passenger ‘air ships’ was seen as obvious. Indeed Black not including one in his painting would have likely been more controversial than the opposite. In everything from Black’s painting to hundreds of children’s books and magazines, and many forward-thinking learned articles and books, the skies of the future were lousy with airships.

Detailed illustration of possible London airship station, The Sphere, 1919. Note the connecting ‘airship train’ service – similar, one presumes, to an ‘ocean liner train’. Jonathan Roberts’ collection.

The poor cousins

At the time airships certainly seemed as viable a transport option as aeroplanes. Both had begun development at about the same time, but the latter were small, uncomfortable, unreliable, noisy and (in most cases) extremely draughty. Although faster than dirigibles, aeroplanes had to land every few hours to refuel and had extremely limited passenger and payload capacity, so were not seen as a serious contender for long-distance transportation or mail service.

In comparison, dirigibles could fly for days without stopping and carry dozens of passengers in smooth comfort, and tons of mail and freight. Airships also offered passengers ocean liner comfort without the sea-sickness and with a shorter journey time. Over land, no train could compare to the stability and calm ride of airship travel, at least in good or average weather. Airships could navigate around most bad weather.

By 1924 airships had a cumulative 72 years of airborne operating experience, much accelerated by the war, whilst aeroplanes had only 16 years.  Both means of aerial transport had made three Atlantic crossings each, but airships had carried a total of 72 people whilst aeroplanes had carried only six. More importantly, only three Atlantic airship crossings had been attempted and all of them had been successful. The same was not true for aeroplanes, which had a number of fatal failed crossings on their scorecard. 

Opening of the Royal Airship Works

Cardington, five miles south east of Bedford, is where the Shorts Brothers Engineering Company, having won a contract for the construction of an airship in 1916, set up their manufactory. The presence of numerous locally-based light engineering companies and a gentle prevailing wind were key reasons for the site’s selection. This airship base was nationalised in 1917 under the Defence of the Realm Act and renamed the Royal Airship Works.

Cardington is 44 miles north of Whitehall as the airship flies. Before you reach for your period Bradshaws, there were four weekday trains between St. Pancras and Cardington (changing at Bedford) on the Bedford-Hitchin line, or you could go from Kings Cross to Hitchin and change there. Branch line and fast London connections ranged from good to awful, and the typical journey took 1½ hours to well over 2 hours.

As a result for passengers there would likely have been a special airship train (like an ocean liner train service) to Cardington had regular airship services become the norm. Such a journey would have been about 1¼ hours. There was railway freight track right into the Royal Airship Works, which would be ideal for bringing passengers right into the base.

Cardington’s airship shed was by far the largest building in Britain at that time, and was large enough to construct and house airships to rival the largest future Zeppelins. This was crucial, as the size and range of an airship was above all limited by the size of the shed it was built in.

Imperial dreams

At the 1921 Imperial Conference proposals were tabled for an Imperial Air Service. This would service passenger and mail routes between London and key parts of the Empire – most notably South Africa, India, Australia and New Zealand.

The proposal caught the eye of aeronautical engineering firm Vickers. By 1921 Vickers had already dipped their toes into airship design with their R.80 dirigible in November of 1917. R.80 was originally designed in the traditional Zeppelin Zahn shape – cylindrical with streamlined ends – but Chief Designer Barnes Wallis2. soon decided to reshape the envelope of the airship. The result was a constantly curved, streamlined design that massively reduced air resistance.

 One of the finest aeronautical engineers of the 20th century, Barnes Wallis was also responsible for the Wellington Bomber and the ‘Bouncing Bomb.’

R-80, via the excellent airshipsonline.com

Vicker’s proposal

Sensing an opportunity, Vickers and Shell Oil floated the idea of creating a company which would build and operate a five-airship Empire service for the British government in 1922. Initially, this would fly bi-weekly to India and Australia. The airships would be about 3.8 million cubic feet in size (as large as the later Graf Zeppelin LZ.127) with a cruising speed of 55 knots (63 mph). These two companies expected that the service would lose money in its first two years, but turn a profit once construction costs and depreciation were paid off.

The proposal included stop-over bases with mooring masts, with the following timetable from London:

CitySteamship (days)Airship (days)
Bombay175 ½
Rangoon21-217 ½
Hong-Kong288 ½
Australia3511 ½

In 1923 Vickers formally proposed the plan to the Government. It was rejected, but it planted a seed in the minds of several politicians.

The Air Ministry steps in

Alongside Vickers’ efforts, the Air Ministry itself had constructed a number of airships. The largest of these was R.38 in 1921, which was part of an export order to the United States (based on the lightweight Zeppelin LZ.96 design). Tragically whilst executing a turn at full speed in calm weather, she broke in two mid-flight and fell to earth, where she then caught fire. The accident resulted in a heavy loss of life and the subsequent inquiry determined that the Air Ministry had not performed any calculations whatsoever of the aerodynamic forces acting on the ship in flight.

Rescuers clamber over the wreckage of R.38, courtesy U.S. Naval Historical Center.

In turn, the Air Ministry blamed the R.38 disaster on her naval designers. R.38 had originally been destined for uS military service and they had designed the airship to German wartime specifications. Those specifications placed a strong emphasis on keeping overall weight extremely low – necessary in wartime where there was a need to avoid anti-airship fire from ground-based guns, but far less critical once R.38’s role had changed to that of a peacetime craft.

None of this should have excused the Air Ministry from performing any structural analysis of the R.38 design, nor from realising that German bombing Zeppelin had very different design needs to a civilian airship.Despite this, none of the Air Ministry officials in charge of developing were disciplined or held accountable in any way.

The Imperial Airship Scheme

In 1924 Britain elected its first Labour Government. The new Prime Minister, Ramsay MacDonald, was keen to demonstrate the superiority of state-run enterprises. One flagship project which soon emerged was the Imperial Airship Service – a new strategic plan for airships to carry passengers, post and parcels on ‘All-Red-Routes’ linking British territories across the Empire, with London as the hub. The requirements were for two airships, larger than any existing or planned dirigibles at that time, to fly with one stop from London to India.

Alternatively known as the Imperial Air Communications Scheme, it was also in part seen as a way of binding the Empire more closely together, reduce the isolationist tendencies of some Dominions and keep the Empire commercially competitive with the United States. To many, it was the obvious way forward and would demonstrate Britain’s continuing scientific advancement and technical innovation, led by her finest engineers and minds. It was a popular scheme with cross-party support, and development continued even after the Labour government had fallen and the Conservatives returned to power.

The endeavour was the largest project of its kind, and its only competition in the mid- and late 1920s was from Germany’s smaller Graf Zeppelin LZ.127. This was planned to be the pioneer airship of a new fleet of Zeppelins which would be larger still (these eventually appeared in the mid-1930s as the Hindenburg and Graf Zeppelin II).

Construction began on the LZ.127 Graf Zeppelin in the mid-1920s, after the delivery of the LZ.126 to the United States. This was the first German airship to be constructed without risk of prohibition or enforced seizure by the Allies for reparations after WW1 (LZ.120 and 121 were seized, and 122-125 were prevented from being constructed). Nevertheless the Graf Zeppelin was delayed by funding difficulties.

In August 1929, sponsored by William Randolph Hearst the US media magnate, she made the first around the globe airship flight between New York City (Lakehurst airfield is actually in New Jersey), Friedrichshafen, Tokyo via the USSR, Los Angeles and returning to New York City. There were also start and finish flights from Friedrichshafen to New York, and return.

Britain looks to lead

Graf Zeppelin’s development and global circumnavigation may have been much publicised, but Britain was set to leapfrog Germany in the airship race. Not until the Hindenburg and Graf Zeppelin II seven years later would Germany construct passenger airships of similar size, range and carrying capacity to the planned British Imperial Airship fleet.

Part of the thinking behind the Imperial specification was for the airships to carry 200 soldiers and kit over long distances in case of war. Alternatively the airships could become aerial motherships for four or five biplane fighters for home defence, carried up to 15,000 feet and released to intercept enemy bombers off the coast. This was based upon plans for the R.33 to carry a parasite fighter, which was trialled a year later with a small De Havilland DH. 53 Hummingbird. The Hummingbird was successfully launched and retrieved. Full size RAF Gloster Grebes were then launched from the R.33, and returned to airfields.

R.33 with Gloster Grebe aeroplanes tethered beneath.

The Cabinet Committee appointed to investigate the airship scheme determined that this would be an ideal competition between state and private industry, so they let concurrent contracts for the private sector. Vickers were to design and construct the R.100, with the Air Ministry at the Royal Airship Works at Cardington designing and building the R.101 to the same specification.

The Imperial Airship Competition

It was felt by the Cabinet Committee that having two competing prototype designs would double the level of innovation. 

These airships were planned to be larger and more innovative than any other existing.
The Imperial Airship specification was for two airships with:

  • a structural weight not exceeding 90 tons
  • 62 tons disposable lift
  • accommodation for 100 passengers
  • fuel for 57 hours’ flight
  • a cruise speed of 63 mph (55 knots/101 kmh) and maximum speed of 70 mph (61 knots/110 kmh).

This would result in airships capable of flying from Cardington to India in six days, Australia in ten (both journeys with refuelling stops), and Canada non-stop in three.

The R.100 and R.101 each had an initial budget of £350,000 (about £26m at 2021 value), but the overall budget including research, infrastructure and flight testing was £2.4m (equivalent to an astonishing £178 million in 2021 pounds).

Airships of 5 million cubic feet of gas capacity, and approximately 735ft long, were calculated to satisfy these requirements. To put into perspective, this is only slightly shorter than One Canada Square at Canary Wharf turned on its side and three times longer than an Airbus A380.

Radical design

Neither Vickers nor the Royal Airship Works were deterred by the then-recent airship disasters of the R.38, France’s Dixmude (lost in a thunderstorm, originally the German LZ.114), or Italy’s Roma. The Roma was the world’s largest semi-rigid airship at 1.2 million cubic feet and had been sold to the US Navy and crashed apocalyptically during testing. Both British design bureaus believed that these disasters could have been prevented with better designs, and that hydrogen airship travel could be made acceptably safe.

Both the R.100 and R.101 were almost identically streamlined. They used the same principles as R.80, with long pointed tails shaped like a teardrop for maximum aerodynamic efficiency. Both ships also incorporated their passenger compartments within the airship itself. Combined, these innovations made them the most aerodynamic airships constructed to date. 

Both ships went with internal passenger and crew accommodations for a number of reasons. The original Zeppelin style gondola slung under the hull limited the configuration to a long narrow space. Moving the passenger area internally allowed a much more spacious layout, created less aerodynamic drag, and reduced the effect of passenger movement on the trim of the ship. The disadvantage was the loss of approximately 100,000 cubic feet for gas, but on the long voyages for which these ships were designed this was more than counteracted by the reduced drag and consequent fuel requirements.

On each airship, an internal gangway extended from near the nose, where the passengers boarded, along the bottom of the hull to the passenger and crew accommodations, to the fins, to the very tail where a lookout position was placed. In addition there was a two man winching position at the very tip of the nose, with a bow lookout 20 feet back to oversee the mooring approach and process. A ladder up the centre of the ship opened to a hatch to allow access to the top of the hull, from whence sextant navigation sightings were made.

A general issue with airships of that era was how best to compensate for the weight of engine fuel consumed during flight. To maintain the ship’s equilibrium as the ship becomes lighter, traditionally lifting gas was vented (ie wasted). The Graf Zeppelin used ‘blaugaz’ for fuel, chemically similar to coal gas. It was non-explosive, and because it weighed approximately the same as air, burning it and replacing its volume with air did not lighten the airship.

An elegant Imperial solution incorporated into both ships was a rainwater collection system along the top of the hull. This accumulated water ballast to compensate for the loss of weight of the consumed fuel, keeping the weight of the ship constant, and preserving the hydrogen.

To help avoid potentially dangerous storms, both ships’ control cabs were equipped with the latest radios to receive weather forecasts and conditions. They also both carried an experienced meteorologist on board and their higher maximum speeds gave them greater ability to avoid bad weather.

Telegraphs, and speaking tubes in case of electrical failure, connected the control car to the engines and other positions within the ship. 

Strategic sausage skins

Dirigibles contained very large gas cell bags, each made from goldbeater skin painstakingly sewn together from the intestines of 50,000 cattle by a Zeppelin subsidiary in Germany. Goldbeater skin is the processed outer membrane of an animal intestine, valued for its strength against tearing.

Goldbeater skins had been a major strategic material for Germany during the Great War, to the extent that occupied territories in Poland, and northern France, as well as the citizens of Austria, had been banned from making sausages so that the skins would be available for Zeppelin manufacture.

The gas bags unfortunately absorbed moisture quite readily, which weakened them and made them susceptible to rip if exposed to the wind by a break in the cover.

Safety was designed into both airships, in the form of gas bag valves and internal wiring to hold the gas bags securely in place. Shifting of airbags in turbulent air greatly magnified flight trim and control problems.

R.100 over the Canadian Bank of Commerce building in Toronto in 1930, then the largest building in the Empire. Courtesy City of Toronto.

Pressure relief valves were fitted to the gasbags of each dirigible to deal with unexpectedly large rates of ascent, set at 2,500 feet per minute, such as might be experienced near a thunderstorm. The impetus for this was the loss of the airship USS Shenandoah in such a storm in September 1925. This was a US-built airship using a strengthened version of the lightweight LZ.96 design, with German technical assistance, and operational from 1923. Its last flight had been insisted on by the Navy Department for promotional purposes, despite the poor weather anticipated. Gas bags were ruptured by excessively fast height gain, and there was also a major hull structure failure.

Stay safe

In the wake of the R.38 disaster in 1921, the Air Ministry Inspectorate introduced new rules for airship safety in 1924. These required extensive stress calculations to be performed on the ship’s structure, rather than relying on empirical data as was the Zeppelin practice.

A subsequent effect was that both R.100 and R.101 had fewer longitudinal girders to simplify the stress calculations, thereby making the structure lighter as well. The stress calculations performed by both design teams are remarkably close to modern practice.

Imperial upgrade

To house and build the new fleet, Cardington No. 1 Shed was lengthened in 1927 by 10m (30ft), and the shed from H.M. Airship Station, Pulham3., was dismantled in 1927 and re-erected at Cardington as No. 2 Shed, with additional sections added to make it as long as No. 1 Shed.

In its heyday RNAS Pulham was a major Airship station in its own right, complete with Hydrogen plant.

The Royal Airship Works itself was expanded to include a hydrogen plant, foundry, rolling mill and factory to manufacture duralumin alloy. The Meteorological Office established a Research and Forecasting Station there as well to track and predict weather conditions on the main Empire routes.

Cardington also became home to one of the most innovative docking technologies of the airship age. For the first time, an airship mast was developed to resist a pull of 30 tons in any direction, obviating the need for very large ground handling parties to bring a dirigible in to land. The 200ft high mast also contained a passenger lift which could accommodate twelve passengers at a time, as befitted the distinguished passengers expected. The Royal Airship Works mast was completed in 1926.

In the next part of this series we will look at the construction of the two airships in detail as well as their flights (planned and actual) between London and the world.

London 2026 AD this is all in the air, by Montague B Black, 1926

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