R23X-class airship

The R.23X class was a British class of rigid airships developed during the First World War from the experience gained with the 23 class. Four ships were planned, numbered R.27 to R.30, but the programme was re-evaluated after the German Zeppelin L 33 came down almost intact in Essex in September 1916 and British engineers could examine it. R.28 and R.30 were cancelled in favour of the improved R33 class, so only R.27 and R.29 were built. The design removed the external keel corridor of earlier ships, which saved weight and improved manoeuvrability, and trials showed a disposable lift of more than eight and a half tons, better than any earlier British airship. Each ship had four Rolls-Royce Eagle engines of 300 horsepower. R.27 was built by William Beardmore and Company at Inchinnan and commissioned on 29 June 1918, but was destroyed by fire in a hangar at Howden on 16 August. R.29 was built by Armstrong Whitworth at Barlow in North Yorkshire, commissioned on 20 June 1918, and became the most successful British wartime rigid airship, the only one to meet enemy action and the only one to sink a submarine, UB-115, on 29 September 1918. She was deleted in October 1919.