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R101 airship, Cardington
Cardington, Bedfordshire, UK
R101 airship, Cardington
associated engineer
Vincent Crane Richmond
date  1926 - October 1929
UK era  Modern  |  category  Airfield/Hangar/Aeronautics  |  reference  TL080469
photo  courtesy National Maritime Museum
The ill-fated R101 was the largest airship in the world. However, she was unwieldy to manoeuvre and suffered repeatedly from lack of lift. During her first scheduled flight to India in 1930, she crashed in northern France and caught fire when her hydrogen gas bags ignited, killing most of those on board. Not surprisingly, airship development in Britain stalled shortly afterwards.
In the 1920s, Britain wanted a reliable air service capable of travelling regularly to the far corners of its empire carrying mail, goods and personnel (troops or civilians). For such long journeys, airships were favoured over the aircraft of the time. Aircraft were heavier and therefore need more refuelling stops. The construction of airships, or dirigibles, was well established. Britain’s first was completed in 1902, though France had pioneered the technology in the late 18th century. In 1917, the first airship shed at Cardington was constructed by the Admiralty, and ships R31 and R32 constructed there.
In 1921, the Cardington site became the Royal Airship Works, and the creation of an Imperial Airship Company was suggested. The following year, aeronautical engineer Charles Dennistoun Burney (1888-1968), a consultant with Vickers Ltd, proposed that the company should design and construct six airships. Though the project received approval in principle, it was delayed.
In 1924, after a change of government, the new Secretary of State for Air, Christopher Birdwood Thomson (1875-1930), started the scheme. Scheduled destinations were to include the UK, Canada, Egypt and India. The projected fleet began with two ships, R100 and R101. The R stands for 'rigid', so-called because the craft’s fabric envelope is supported by a structural frame.
R100 was to be be built by the Airship Guarantee Company (a subsidiary of Vickers), using existing technology, while R101 was to be constructed at Cardington, funded by the government. The idea was that Vickers would not have a monopoly and that R101 could incorporate the latest innovations.
Both airships had to be able to transport cargo and up to 100 passengers at 112.6kph (70mph) on non-stop flights in all weathers. They were to be kept aloft by hydrogen gas, as helium (which is non-flammable) was scarce and expensive. The anticipated advantage was that the airships would take five to six days to travel between Britain and India, with one refuelling stop, whereas aircraft of the time needed eight days and 21 stops. Sea transport took a minimum of four weeks.
In 1926, work began on R101. The shed at Cardington (now known as Shed No.1), was enlarged to accommodate her. When completed in October 1929, R101 was 224m long and 40m in diameter. Her top speed was 99kph.
In elevation, R101 was an an elongated teardrop in shape. The front third was circular in cross-section and the remainder tapered to an ellipse, wider than it was deep, to reduce drag as much as possible (to just over 2%). The shape had been determined through wind tunnel experiments on model airships in 1924-6 at the National Physical Laboratory, London.
The main structural skeleton consisted of 17 transverse ring frames joined together by 15 continuous longitudinal girders. The frames divided the ship into 16 compartments, each containing a bag of gas.
The rings consisted of straight lengths between girders — triangular lattices of one inner member and two outer members about 3m apart. The girders, which ran over the outer face of the rings, were also triangular lattices. Frames and girders were of high-tensile stainless steel tubing coated with lacquer.
The girders resisted the bending moments of the structure, and a network of diagonal wires, between and in the plane of the frames, gave shear resistance. All structural metalwork was machined to high tolerances: only 0.83mm in 10m.
The gas bags were made of cotton fabric lined with gold-beater-skin (a natural membrane taken from the intestines of oxen), varnished inside and out. Each bag was held in a cradle of wires that transmitted the lift from the bag to the hull. The bags had automatic relief valves so that gas could be released if the internal pressure was too high.
The outer fabric cover was stretched over the main girders and intermediate longitudinal flexible ‘reefing’ girders of duralumin (an alloy of aluminium often used in aircraft), which adjusted the tension, giving the hull a 30-sided envelope.
The envelope was made of linen treated with a celluloid varnish called ‘dope’, applied after the fabric had been stretched over the framework. It had air inlets and outlets to prevent a vacuum forming inside. The ship had four tail fins, set at right angles to each other, each with a 13.4m long control flap for steering.
Flying the airship was done from a gondola control car located below the ship's midsection. From there the steering flaps were operated by a system of cables, and instructions relayed to the engine rooms. Further observations were made from a cockpit in the tail and a covered platform at the top of the craft.
R101 was powered by five water-cooled 436kW Beardmore Tornado diesel engines, with auxiliary starting engines of 30kW. The two (port and starboard) forward engines were reversible, the two just aft of the midsection and the one towards the tail drove forwards only. The engines sat in pods suspended from the main hull, large enough for mechanics to move about inside, with individual fuel storage tanks of 224gal.
The accommodation was located amidships, in the belly of the hull. It included 50 cabins with one, two or four berths, and a dining room for 60 people, crew quarters, kitchens, washroom facilities, two promenade decks and, surprisingly, an asbestos-lined smoking room. R101 also carried 8 tonnes of water ballast and 29.5 tonnes of fuel for the engines.
Out of her hangar for the first time on 12th October 1929, R101 was moored by the nose to the top of a nearby tapering steel lattice mast (TL082470), 62m high and 21m base diameter. Her tail was moored by a weighted guy rope. The mast was design in such as way that the airship could always face into the wind. Passengers climbed a staircase inside the mast and entered the ship on a gangway from the top platform. Hydrogen and water were supplied at the mast head, though R101 could also be filled with hydrogen inside the hangar.
On 14th October 1929, she made her first flight, a return journey from Cardington to London. There were 38 crew and 14 passengers, including the ship’s designer, Lieutenant Colonel Vincent Crane Richmond (1893-1930). The captain was Major George Herbert Scott (1888-1930), the first man to cross the Atlantic in an airship.
R101 made six further trial flights before being rehoused in the hangar on 30th November 1929. The trials had included one trip of more than 30 hours, flying as far as Scotland and Ireland.
But even with 138,490 cu m of hydrogen in her bags, she didn’t have enough lift to maintain her ideal flying height of 457m. She spent six months under cover while the wire cradles holding the bags were lengthened, increasing the volume of gas to 141,460 cu m. The many holes that had appeared in all but one of the bags were repaired and the wiring padded to prevent further chafing.
On 23rd June 1930, R101 was once again moored to the tower. The humid weather caused two splits to appear in the outer cover, which were repaired in situ. On 27th and 28th June, she took part in displays at the RAF Hendon Air Pageant but went into a series of steep dives on the return journey. Fortunately, she landed safely at Cardington.
Clearly, yet more lift was required if R101 was to be a commercial success. During summer 1930 an additional bay was added to her central section, increasing the total length to 237m. She now carried 155,930 cu m of gas in 17 bags and could fly at up to 114.2kph (71mph). Her disposable lift was now calculated to be 50.1 tonnes. Meanwhile, defects in the outer covering had been treated with a rubber solution. This reacted with the dope and weakened the fabric so that it had to be strengthened locally with reinforcing strips.
On 1st and 2nd October 1930, R101 took to the air once more for a return flight over East Anglia and the North Sea. At the time, she was the largest man-made object ever to fly. On 2nd October, the Air Ministry issued her Certificate of Airworthiness. However, in all her 11 trial flights R101 had never undertaken a full-power test, though she had flown at full speed.
Two days later, at 6.36pm GMT on 4th October, R101 cast off on her inaugural long-distance journey from London to Karachi, via Ismailia in north eastern Egypt. It was dark and raining. She was heavily loaded and had to jettison 4 tonnes of water ballast to compensate. The fuel load of 25.4 tonnes was more than sufficient for the journey. A total of 54 people were on board: six passengers and 48 officials and crew.
By the time R101 was over the Channel, she was reported to be cruising at 100kph (54.2 knots or 62.4mph) and was recovering rainwater from a catchment on top of the envelope to act as ballast. The wind speed began increasing as R101 crossed the French coast.
At approximately 2am GMT on 5th October, R101 passed low over the city of Beauvais, north west of Paris, heading south. She hit gusting winds, resulting in a tear that allowed gas to escape from the forward section. She dived twice and landed less than 10 minutes later near Allonne, in the Oise départment of northern France. Though she hit the ground at only 22kph, the forward starboard engine was badly damaged. It’s likely that the hot engine ignited the escaping hydrogen. R101 was engulfed in flames, which soon destroyed the gas bags and most of the envelope’s fabric.
Only eight people survived the fire — a wireless operator, a foreman, four engineers and two riggers. Both riggers died later from their injuries. Among the dead were Lord Thomson, Richmond, Scott, the captain RAF Flight Lieutenant Herbert Carmichael Irwin (1894-1930) and first officer Lieutenant-Commander Noel Grebowski Atherstone.
That same day, King George V sent a message of sympathy. On 11th October, a memorial service for the 48 victims was held at St Paul’s Cathedral in London. Their remains were transported to Cardington where they were buried together in St Mary’s churchyard. In 1931, a memorial tomb (TL085479) was erected near the spot. R101’s ensign was recovered from the crash site and now hangs in St Mary’s church.
The wreckage remained where it fell until 1931 when a specialist Sheffield company salvaged the metal skeleton. Apparently, the German Zeppelin company also purchased 5,000kg of duralumin from the site. A small concrete obelisk, unveiled on 1st October 1933 in the presence of the six survivors, marks the place where R101 crashed (lat/long 49.390567 / 2.110260).
In all her 12 flights, R101 had flown for a total of only 127 hours and 20 minutes.
Girders and frames: Boulton & Paul Ltd, Norwich
Research: ECPK
"Report of the R.101 Inquiry",
Secretary of State for Air, HMSO, London, March 1931
"The Loss of H.M Airship R101" in Flight magazine, 10th October 1930
"Building the Structure of the R.101"
in The Aircraft Engineer, 29th November 1928
reference sources   CEH E&C

R101 airship, Cardington