His Majesty's Airship R100 was a privately designed and built British rigid airship made as part of a two-ship competition to develop a commercial airship service for use on British Empire routes as part of the Imperial Airship Scheme. The other airship, the R101, was built by the British Air Ministry, but both airships were funded by the Government.
R100 was built by the Airship Guarantee Company, a specially created subsidiary of the armaments firm Vickers-Armstrongs, led by Commander Dennis Burney. The design team was headed by Barnes Wallis, later famous for his invention of the bouncing bomb. The design team also included Nevil Shute Norway as the senior stress engineer .
R100 first flew in December 1929. It made a series of trial flights and a successful return crossing of the Atlantic in July–August 1930, but following the crash of R101 in October 1930 the Imperial Airship Scheme was terminated and R100 was broken up for scrap.
Background
R100 was built as part of a British government programme to develop airships to provide passenger and mail transport between Britain and the countries of the British Empire, including India, Australia and Canada. This had its origin in Dennistoun Burney's 1922 proposal for a civil airship development programme to be subsidised by the Government and carried out by a specially established subsidiary of Vickers. When the General Election of 1923 brought Ramsay MacDonald’s Labour administration to power, the new Air Minister, Lord Thomson formulated the Imperial Airship Scheme in its place. This called for the building of two experimental airships: one, R101, to be designed and constructed under the direction of the Air Ministry, and the other, R100, to be built by the Vickers subsidiary under a fixed price contract.
Design and development
R100 was constructed at the former RNAS Air Station Howden in Yorkshire, a remote location from Howden and from Hull. Design work began in 1925 while at the same time the somewhat rundown site was put in order and a hydrogen-generating plant installed.
The specially established subsidiary of Vickers, 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 structure, so that the girders had to be varnished. For three years the assembly work was close behind that of the designers, and the progress of the design work was the determining factor in speed of construction.
Airframe
Since wind tunnel tests showed that a 16-side transverse section had about the same drag as a circular one, both R100 and R101 used a smaller number of longitudinal girders than previous airships to simplify stress calculations. Even so, the calculations for the transverse frames required hand computation that took two or three months to produce a solution for each frame. The thoroughness of the stressing calculations was a consequence of new Air Ministry criteria for the strengths required of airships, formulated after the catastrophic structural failure of R38 in 1921. Fewer longitudinal girders resulted in larger unsupported panels of fabric in the envelope, and flight trials were to prove that the R100's covering was barely adequate. The envelope of R101 was also unsatisfactory and a failure in its cover was possibly a cause of its crash.
Barnes Wallis created the frame of the airship using only 11 standard components. The 16 longitudinal girders were formed of three tubes each, formed from strips of Duralumin wound into a helix and riveted together. These connected 15 polygonal transverse frames, which were held in shape by wire bracing connected to a central longitudinal girder running the length of the ship. A further consequence of the new rules for airframe stress design 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.