23-class airship

The 23 class were rigid airships produced in the United Kingdom during the First World War. They were designed by Vickers, who also built the first and last of the four ships, with the other two being built by William Beardmore and Company and Armstrong-Whitworth. While the 23 class was never used in combat, the four ships provided many hours of valuable training and experimental data for British airship crews and designers. Although a total of 17 of these ships were contemplated at one time, only four were ever built. The 23 class was found to be significantly overweight, leading to its cancellation in favour of the more-refined R23X class.

Design and development
The 23 class had a structure similar to that of the earlier 9r. An extra bay was inserted amidships, and the nose and tail widened allowing more gas capacity and increased lift. The exterior keel had a widened section amidships incorporating a bomb bay, sleeping quarters, radio room and toilet. Three gondolas were suspended from the keel. The fore and aft cars each contained a single 250 hp Rolls-Royce Eagle driving twin swivelling propellors, while the middle car contained two "Eagles" with one fixed propeller each. The forward car contained the control room, but there were also emergency controls in the aft car. Ballast and fuel were carried in tanks along the keel. Rudders and elevators were of the cruciform Schütte-Lanz type. The design drawings were approved in October 1915 and a further 16 airships of the same class budgeted for. In April 1916, ten ships were approved, to be built by a further three contractors besides Vickers. However, in light of improving technology and information about German designs, only three more of this class, and two of the improved R23X class were built. The rest would be R31 class ships.

23r


Construction was commenced by Vickers on 1 January 1916 at Barrow-in-Furness, Cumbria. Construction was delayed by materials shortages (including the shortage of linen caused by the Easter rising in Ireland) and strikes. The trial flight took place at Barrow on 19 September 1917. The ship was found to have less than the rated lift so the dynamos, bomb gear, and furniture were removed to save weight. A 240 hp Maybach engine from the crashed Zeppelin L 33 replaced the Rolls-Royce in a new rear car, this one without emergency controls.

23r flew to RNAS Howden, Yorkshire, on 15 October 1917, and then to RNAS Pulham, Norfolk, on 29 October. She flew over central London on 6 December, bringing the city to a standstill and generating a wave of patriotic fervour. Despite the identification markings being clearly visible to millions of Londoners, the censors banned publication of the name of the ship. A record flight of 40 hours 8 minutes was made in May 1918, as well as experiments with defensive armament of a 2-pounder (40 mm QF gun and three machine guns. The shells from the large gun caused the ground crew at Pullham some alarm when they ricochetted off the ground instead of exploding harmlessly. In July, experiments were made with parasite fighters, in the hope they could defend the airship. First an unmanned, then a manned, Sopwith Camel were launched successfully. In November, the experiment was successfully completed with two other manned Camels. No. 23r overflew the surrender of the German submarine fleet at Harwich in November 1918, before being modified for experiments with the three-wire mooring system in March 1919. She was deleted in September 1919 after a total of about 320 hours.

24r
24r was built by William Beardmore and Company at Inchinnan, in Renfrewshire, Scotland. When the decision was taken to lighten the overweight 23r and 25r in October 1917, 24r was tested as well. The problem was found to be even worse, with 24r weighing around 1,500 lb (680 kg) more than her sisters – a difference that was eventually traced to the use of slightly larger and heavier fasteners throughout her structure. A solution was required with some urgency, since Beardmore's construction shed needed to be cleared so that work could begin on R34, but the problem was exacerbated by 24r needing all the lift possible in order to safely navigate the hilly Scottish countryside. Eventually, the decision was taken to completely strip her aft power car – removing the engine and all associated machinery. While this gave 24r more than enough lift, it limited her top speed to only 35 mph (56 km/h).

It was intended that the rear power car would be eventually replaced with one of lighter design, but this was never carried out, and 24r operated throughout the war with only three engines. On one occasion, this led to a situation over Bass Rock where the airship was held immobilized by a headwind, prevented from making any headway at all. She was eventually retired in December 1919 with a total flight time of 164 hours and 40 minutes over a distance of 4,200 mi (6,720 km).

25r
25r was built by Armstrong-Whitworth and completed five weeks after 23r, in October 1917. When found to have the same weight problems during trim trials carried out in a hangar at Armstrong-Whitworth's airship works at Barlow, North Yorkshire, she was similarly lightened, carrying out her first test flight on 14 October 1917. In later flights, another problem emerged in the form of surging within her gas bags. This had the effect of suddenly and unpredictably moving the ship's centre of lift, thereby causing instability. Despite this problem, the airship (by now known as R 25) was officially accepted into service on 23 December 1917, and continued in service until September 1919, by which time she had flown 221 hours and 5 minutes and covered 5,909 mi (9,454 km).

R26
R26 (the first airship designated under the new system of adding an "R" prefix rather than an "r" suffix for rigids) had the benefit of only being in the early stages of construction when the weight problems with her sisters were discovered, allowing weight-saving measures to be implemented from the outset. On 4–5 June 1918, she set a new endurance record for the 23 class by carrying out a patrol of 40 hours 40 minutes. With 23r, she oversaw the surrender of the German U-boats at Harwich, before being assigned to experiments in early 1919 to investigate the practicalities of mooring airships in the open. While promising at first, her envelope was eventually soaked with rain, and the airship was subsequently beaten into the ground by a snowstorm. Although refloated by removing her power cars, the structural damage was found to be too great to warrant repairs, and she was struck off for scrap on 10 March.

Operators

 * Royal Navy
 * Royal Navy