R100
R100 on the mooring mast in St. Hubert, Quebec
Role	Airliner
National origin	United Kingdom
Manufacturer	Vickers
First flight	16 December 1929
Number built	1

HM Airship R100 was a privately designed and built rigid airship made as part of a two-ship competition to develop new techniques for a projected larger commercial airship for use on British Empire routes. The other airship, R101, was built by the Air Ministry, but both airships were funded by the Government.

One goal was to eventually offer a regular and comfortable trans-Atlantic service, akin to that eventually offered by the German Hindenburg. Soon after 1920, Vickers' experts had calculated that the fare on an airship journey might be £45 (around US$215 at the time),^[1] compared to a contemporary fare for the journey by ship of £115 (about $550), making the journey quite competitive.

R100 was built by the Airship Guarantee Company, a company created solely for the purpose, as a subsidiary of the armaments firm, Vickers-Armstrongs. The managing director was Cdr Dennis Burney, and the design team was led by Barnes Wallis, then a well-respected airship designer. He later became famous as the designer of the Vickers Wellington and the inventor of the bouncing bomb. The design team also included Nevil Shute Norway as senior stress engineer.^{[N 1]}

Design and development[link]

Passing over the Jacques Cartier Bridge in Montreal, August 1930

R100 was constructed at the former RNAS Air Station Howden in Yorkshire, a remote location 3 mi (4.8 km) from Howden and 25 mi (40 km) from Hull. Design work began in 1925 while at the same time the somewhat rundown site was put in order and readied for construction to begin, including installation of a hydrogen-generating plant.

The Airship Guarantee Company faced substantial difficulties. The contract for R100's construction was a fixed price one and it was obvious from very early on that the project would incur a loss, and so economies were made; for instance, only a dozen machine tools were in use for construction of the airship. There were also difficulties in finding skilled workers due to the remoteness of the location, and a large proportion of the workers were local people who had to be trained. Conditions in the unheated airship shed were also poor: the roof leaked, ice formed on the girders in winter, and condensation caused corrosion of the airship's duralumin, so that the girders had to be varnished. This was done so well that when the ship was eventually broken up the structure was in perfect condition.

For three years the actual assembly work was close behind that of the designers, and the progress of the design work was the determining factor in speed of construction. Early in the design process it was realized that the huge airship could be steered by hand without needing servo assistance. When the designers learned that R101 had been fitted with servo motors at a substantial cost in weight and money they thought that they had made a mistake and rechecked their calculations. They ended up by concluding that they had been correct, and in practice it was discovered that the finished airship could be steered by a single helmsman.

Construction[link]

In both R100 and R101, it had been decided to use relatively few longitudinal girders compared to previous ships so that more accurate stress calculations could be made. Even so, the calculations for the transverse frames required hand computation that took two or three months to produce a solution. The thoroughness of the stressing calculations was a consequence of new Air Ministry criteria for the strengths required of airships, formulated in response to the catastrophic structural failure of R38 in 1921. Fewer longitudinal girders, however, meant that there were larger unsupported panels of fabric in the outer cover. Flight trials were to prove that the R100's cover was barely adequate. The cover of R101 was also unsatisfactory, although for different reasons, and a failure in its cover was probably the major cause of its crashing.

Barnes Wallis effectively created the frame of the airship from only 11 standardized components fitted into a non-rectilinear framework. The girders of R100 were formed of three Duralumin tubes formed from helically-rolled and riveted strip, while the transverse frames (polygons made up of girders) were joined together by longitudinal girders.^[2] A further consequence of the new rules for stressing was that a new way of harnessing the lifting force of the gasbags had to be found. Wallis's solution to this problem later led to his innovative geodesic airframe fuselage and wing design for the Wellesley, Wellington and Windsor bombers. A further innovation he introduced was to colour code all the airship's wiring (a technique invented by Wallis and used for the first time on R80).

R100 was built suspended from the roof of its shed. The individual transverse frames were assembled horizontally then lifted up and slung from roof-mounted trackways before being slid into position and attached to the adjacent frames using longitudinal members. The ship remained suspended until the gasbags were inflated with hydrogen.

By summer 1929 the ship approached completion and her gasbags were inflated. Her volume was a little over 5,000,000 cu ft (140,000 m³) giving a gross lift of about 156 tons. Her tare (empty) weight was around 102 tons, leaving 54 tons for fuel, oil, ballast, crew, and passengers. Following inflation of the gasbags, her outer covering of linen fabric painted with aluminum aircraft dope^[2] was put in place, and she was completed in November 1929.

Propulsion[link]

It had originally been intended to design special engines for R100 which would be fuelled by hydrogen and kerosene but after a year's work it was realized that the engine would not be developed in time and it was decided to fit Beardmore Tornado diesel engines that were being developed for the Air Ministry for installation in R101. However at a very early stage the Diesel engines were judged unsuitable due to their weight and other reasons. Wallis finally settled on the use of six reconditioned Rolls-Royce Condor petrol engines housed in three gondolas even though the fuel, with its lower flash point, was considered in some quarters to be a fire risk.^[3] A few months before the R101's first flight, her designer also urged the fitting of petrol engines due to the excessive weight of the proposed diesel engines, but this was refused by the Air Ministry on the grounds that they had been developed from locomotive engines especially for R101 and therefore had to be used.^[4]

R100's designers had arranged for two of the airship's six engines to be fitted with gearboxes providing a reversing capability to slow her down as she approached a mooring mast, and were amazed to learn that because of the failure of the proposed variable-pitch propellers four of R101's engines had no reversing capability and the fifth engine would only be used for slowing the craft down,^[4] at a cost of three tonnes weight including its gondola. Later, two of the engines were made reversible by an adjustment to the camshaft.

Operational history[link]

First flight[link]

R100 made her maiden flight in the morning of 16 December 1929. After departing Howden, she flew slowly to York then set course for the Government Airship Establishment at Cardington, Bedfordshire, cruising at around 50 mph (80 km/h) on four engines, reaching the destination in two hours flight time. At the two huge hangars at Cardington (both of which still survive), both the private enterprise team and the other representing the Air Ministry competed to establish which was the better design, in part via long demonstration flights.

The following day speed trials were performed. The officials at Cardington refused to believe that R100 could be at least 10 mph (16 km/h) faster than R101. In fact, during a test on 16 January 1930, R100 achieved a speed of 81 mph (130 km/h), making her the fastest airship in the world.^[5] A difficulty arose with the outer covering which tended to ripple and flap excessively. Cine films were taken of this phenomenon which occurred due to the fact that there were relatively few longerons in the airframe design which created wide areas of unsupported fabric. This flapping is clearly apparent in the photos accompanying this feature.

Transatlantic Voyage to Canada[link]

The R100 in Toronto, Canada, 1930

R100's contract originally required a final acceptance trial flight of 48 hours duration, together with a demonstration flight to India. The decision to change the specification to petrol engines prompted a change in destination to Canada as it was reasoned that a flight to the tropics with petrol aboard would be too hazardous. It was also decided that the Diesel powered R101 would make the flight to India instead.

Following a final acceptance trial of 54 hours, R100 was formally handed over to the Air Ministry, and a number of modifications were made in preparation for her transatlantic flight. During her last flight the tail fairing had collapsed due to aerodynamic pressures and her pointed tail was modified, to Wallis's considerable displeasure, to a more rounded form, shortening her length by 15 ft (4.6 m).

Following R101's unsatisfactory trials in June 1930, the Cardington engineers tentatively suggested that the long flights to Canada and India might be postponed to 1931 on the grounds that neither of the two airships was fit to make a lengthy flight at this developmental stage. The R100 team responded that their airship was perfectly capable of flying to Canada, and furthermore the Canadian flight was a part of their contract.

R100 duly departed for Canada on 29 July 1930, reaching the Canadian mooring mast at the airport in Saint-Hubert, Quebec in 78 hours having covered the great circle route of 3,300 mi (5,300 km) at an average speed of 42 mph (68 km/h). The airship stayed at Montreal for 12 days and over 100,000 people visited the airship each day she was there, and a song was composed by La Bolduc to commemorate, or rather to make fun of, the people's fascination with R100. She also made a 24-hour passenger-carrying flight to Ottawa, Toronto, and Niagara Falls while in Canada.

The airship departed on her return flight on 13 August, reaching Cardington after a 57½ hour flight.

Nevil Shute later suggested in his Slide Rule: Autobiography of an Engineer that the success of the R100's Canadian flight indirectly led to the R101 disaster. Prior to the transatlantic flight, the Cardington team could suggest that neither airship was ready for a performance of such duration. However when the R100 returned in triumph they had to either make the flight to India or admit defeat - which would have meant discredit with the consequent danger of losing their jobs.

The end of the British airships[link]

The tale of the design of R100 and its claimed superiority to R101 is told in Shute's Slide Rule: Autobiography of an Engineer, first published in 1954. Although flawed and not quite as overwhelmingly superior as Nevil Shute implied, R100 represented the best that conventional airship technology in Britain had to offer at the time. R101, on the other hand, suffered in comparison not least because of her many groundbreaking but ultimately problematic innovations, most particularly the weight of her diesel engines. In terms of lifting efficiency, both were inferior to the smaller LZ 127 Graf Zeppelin.

After R101 crashed and burned in France, en route to India on 5 October 1930, the Air Ministry ordered R100 grounded. She was deflated and hung up in her shed for a year whilst three options were considered: a complete refit of R100 and continuation of tests for the eventual construction of R102; static testing of R100 and retention of about 300 staff to keep the programme "ticking over"; or retention of staff and the scrapping of the airship. In November 1931, it was decided to sell R100 for scrap. The entire framework of the ship was flattened by steamrollers and sold for less than £600.^[6]

Specifications[link]

R-100 at mooring mast in Bedfordshire, July 1928

General characteristics

• Crew: 37
• Capacity: 100
• Length: 719 ft 9.5 in (219 m)
• Diameter: 133 ft 4 in (41 m)
• Volume: 5,156,000 ft³ (146,000 m³)
• Empty weight: 236,365 lb (107,215 kg)
• Useful lift: 350,610 lb (159,400 kg)
• Powerplant: 6 × Rolls Royce Condor IIIB 12 cylinder, 650 hp (485 kW) each

Performance

• Maximum speed: 81.5 mph (131 km/h)
• Range: 4,095 miles (6,590 km)
• Endurance: 64 hours

See also[link]

Aircraft of comparable role, configuration and era

R101

References[link]

Notes

Citations

Bibliography

External links[link]

Wikimedia Commons has media related to: R-100

• The R100 in Canada (pdf)
• Airship heritage Trust R100
• Flight magazine feature on the R100 from 1929 (pdf)