23-class airship

Vickers (main constructor of 23 class airships)

Industry	Aerospace
Headquarters	United Kingdom
Products	Rigid airships (23 class)

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The 23 class consisted of rigid airships constructed in the UK during the period of the First World War. Initiated in August 1915, the development aimed to enhance the earlier 9r model by Vickers through adding an additional bay and enlarging the gas cells at both bow and stern to boost gas volume. The design was created by H.B. Pratt and Barnes Wallis from Vickers. Among the four units produced, Vickers fabricated the first and final airships, while William Beardmore and Company and Armstrong-Whitworth were responsible for the second and third respectively. Although these airships did not participate in combat operations, they served extensively for training purposes and contributed valuable experimental insights to British airship crews and engineers. Despite plans for a total of seventeen units, only four were completed. The class was ultimately deemed excessively heavy, which led to its discontinuation in favor of the more advanced R23X class.

Design and development

Photograph of 23r taken during the First World War

In July 1915, following proposals to commission additional airships based on the existing 9r model under construction at Vickers, a directive on 28 August tasked Vickers with designing a new airship class derived from the 9r blueprint. To enable swift mass production, the transverse frame design from the 9r was retained; however, lifting capacity was increased by incorporating an extra bay and broadening both the nose and tail sections to house larger gasbags. Much of the structural framework of the 23 class mirrored that of its predecessor. Propulsion was supplied by four 250 hp (190 kW) Rolls-Royce Eagle engines.

The external keel featured a triangular cross-section with a widened midsection incorporating a bomb bay alongside sleeping quarters, a radio room, and restroom facilities. Suspended beneath the keel were three gondolas: the forward gondola housed the control cabin plus one engine powering two swiveling propellers; amidships was a gondola containing two engines each driving fixed four-bladed pusher propellers mounted on outriggers; while the rear gondola held the fourth engine connected to a single two-bladed pusher propeller as well as an emergency control car. Ballast and fuel tanks were installed along the keel structure. The airship employed cruciform-type Rudders and elevators for control surfaces. The design received official approval on 10 October 1915.

Construction

The initial order comprised three airships. Vickers was tasked with building one at Barrow-in-Furness, Cumbria. William Beardmore and Company, located in Inchinnan, Renfrewshire, Scotland, received the contract for the second airship, designated 24r. The third, known as 25r, was commissioned from Armstrong-Whitworth at Barlow, North Yorkshire. Beardmore and Armstrong were responsible for manufacturing many of the components used in these vessels. In December, the Treasury authorized the construction of an additional sixteen airships and approved Government loans to finance the erection of further construction sheds. Subsequently, one more airship was ordered from Vickers, with two more each from Beardmore and Armstrong. However, the Treasury soon imposed restrictions, halting any further airship production until adequate sheds were available to accommodate them.

23r

23r accompanied by Sopwith 2F.1 Camel N6814

Vickers commenced construction of 23r on 1 January 1916. Progress was hindered by shortages of materials—including linen, affected by the Easter rising in Ireland—and labor strikes. The airship’s trial flight occurred at Barrow on 19 September 1917. During testing, it became evident that the lift capacity was below expectations; consequently, to reduce weight, equipment such as dynamos, bomb apparatus, and internal furnishings were removed. A 240 hp (180 kW) Maybach engine salvaged from the downed Zeppelin L 33 replaced the original Rolls-Royce engine in a newly designed rear gondola that lacked emergency controls.

On 15 October 1917, 23r flew to RNAS Howden, Yorkshire, followed by a transfer to RNAS Pulham, Norfolk, on 29 October. The airship’s flight over central London on 6 December caused widespread disruption and stirred patriotic enthusiasm throughout the city. Despite its identification markings being clearly visible to millions of observers, censorship prohibited any publication revealing the vessel's name. In May 1918, it achieved a record endurance flight lasting 40 hours and 8 minutes and conducted trials with defensive armaments including a 2-pounder 40 mm (1.57 in) QF gun alongside three machine guns. The large gun’s shells alarmed ground personnel at Pulham when they ricocheted off the surface instead of detonating safely. July saw trials involving parasite fighter aircraft intended to provide protective escort for the airship. Initially an unmanned and then a manned Sopwith Camel were successfully launched. By November, this experiment culminated successfully with two additional manned Camels deployed. In that same month, No. 23r flew over the German submarine fleet surrender at Harwich. It was later adapted in March 1919 for testing a three-wire mooring system before being retired in September 1919 after accumulating approximately 320 hours of flight time.

Painting depicting two airships of the 23 class at Pulham by John Lavery. The foreground features a tank used during ground handling operations.

24r

In October 1917, alongside the efforts to reduce the excessive weight of 23r and 25r, 24r was also subjected to testing. It was discovered that 24r was even heavier, exceeding the weight of its counterparts by approximately 1,500 lb (680 kg). This discrepancy was ultimately attributed to the incorporation of slightly larger and heavier fasteners throughout its framework. An urgent resolution was necessary because Beardmore's assembly shed had to be vacated to commence work on R34. The challenge was intensified by the need for 24r to maximize lift to safely traverse Scotland's rugged terrain. The final decision involved completely removing the aft power car, including its engine and all related equipment. This modification provided ample lift but restricted the maximum speed to 35 mph (56 km/h).

Plans were made to replace the rear power car with a lighter model eventually; however, this upgrade never materialized. Consequently, 24r operated through the war using only three engines. This limitation led to an incident near Bass Rock where a headwind stalled the airship, preventing any forward movement. The airship was retired in December 1919 after accumulating a total flight time of 164 hours and 40 minutes, covering 4,200 mi (6,720 km).

25r

Constructed by Armstrong-Whitworth, 25r was completed five weeks following 23r, in October 1917. During trim trials conducted at Armstrong-Whitworth's airship facility in Barlow, North Yorkshire, it exhibited similar weight issues and underwent weight reduction measures. Its maiden test flight took place on 14 October 1917. Subsequent flights revealed another complication: surging of the gasbags caused abrupt and unpredictable shifts in the ship's centre of pressure, resulting in instability. Despite this challenge, the airship—renamed R 25—was formally accepted into service on 23 December 1917, remaining active until September 1919. By that time, it had logged 221 hours and 5 minutes of flight time and traveled 5,909 mi (9,454 km).

R.26

R.26 marked the first rigid airship designated with an "R" prefix rather than an "r" suffix under the updated naming system. Being in early construction when weight issues were identified in its sister ships allowed for implementation of weight-saving strategies from the beginning. Between 4 and 5 June 1918, it established a new endurance record for the 23 class by completing a patrol lasting 40 hours and 40 minutes. Alongside 23r, it participated in overseeing the surrender of German U-boats at Harwich before being assigned in early 1919 to experimental trials exploring open-air mooring techniques for airships. Although initially promising, its envelope became saturated from rain, and subsequently, a snowstorm caused it to be driven to the ground. After removing its power cars to refloat it, assessments revealed that structural damage was too severe for repair, leading to its removal from service on 10 March.

Operators

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• Royal Navy

References

• Airships Heritage Trust, 2006, Airshipsonline : Airships : HMA 23 Class
• Higham, Robin. The British Rigid Airship 1908–1931. London: Foulis, 1961.
• Morpurgo, J. E. Barnes Wallis – A Biography, Longman, 1972 ISBN 0-582-10360-6
• Mowthorpe, Ces. Battlebags: British Airships of the First World War, 1995 ISBN 0-905778-13-8
• Tapper, Oliver. Armstrong Whitworth Aircraft since 1913. London: Putnam, 1988. ISBN 0-85177-826-7.
• Lord Ventry and Eugene Kolesnik, Jane's Pocket Book 7 – Airship Development, 1976 ISBN 0-356-04656-7
• Lord Ventry and Eugene Kolesnik, Airship saga: The history of airships seen through the eyes of the men who designed, built, and flew them , 1982, ISBN 0-7137-1001-2