View source for 23-class airship

{{Short description|Rigid training airships in the UK}}
{{EngvarB|date=April 2014}}
{{Use dmy dates|date=October 2019}}
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{{more footnotes needed|date=May 2010}}
{{Infobox aircraft
 |name=''23'' class 
 |image=R23WithSopwithCamelWWI.jpg
 |caption=23r with underslung [[Sopwith Camel]]
 |type=Training airship
 |national_origin=United Kingdom
 |manufacturer=[[Vickers]] (''23r'' and ''R26''), [[William Beardmore and Company|Beardmore]] (''24r''), [[Armstrong-Whitworth]] (''25r'')
 |designer=
 |first_flight=19 September 1917
 |introduction=
 |retired=
 |status=
 |primary_user=
 |more_users=
 |produced=
 |number_built=4
 |variants=
}}

The '''23 class''' were [[rigid airship]]s produced in the United Kingdom during the [[First World War]]. Development of the 23 class began in August 1915 when Vickers was asked to improve the 9r design by increasing its gas capacity by adding a bay and increasing the capacity of the bow and stern gas cells.<ref>Higham 1961, pp. 133–134</ref> The 23-class was designed by
[[H.B. Pratt]] and [[Barnes Wallis]] of [[Vickers]].<ref>Mowthorp 1995, pp. 125</ref> Vickers built the first and last of the four ships. The other two were built by [[William Beardmore and Company]] and [[Armstrong-Whitworth]]. While the 23 class airships were 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.<ref name="Higham 1961, pp. 135">Higham 1961, pp. 135</ref> The 23 class was found to be significantly overweight, leading to its cancellation in favour of the more-refined [[R23X-class airship|R23X class]].

==Design and development==
[[File:THE ROYAL NAVAL AIR SERVICE (RNAS) 1914-1918 Q27575.jpg|thumb|right|Photograph of 23r taken during the First World War]]
Following proposals in July 1915 to order more airships to the same design as the [[No. 9r|9r]] then being built by Vickers, on 28 August Vickers were asked to design a new class of airship based on the 9r. To facilitate rapid mass-production, the same transverse frame design as the 9r were used, but lift was increased by adding an extra bay and by making the nose and tail fuller to accommodate larger gasbags.<ref>Higham 1961, pp. 131–3</ref> The great portion of the 23 class structure was identical to the 9r's.<ref>Higham 1961, pp. 134</ref> Power was provided by four {{convert|250|hp|abbr=on}} [[Rolls-Royce Eagle]] engines. 
<ref name=AHT>{{cite web|url=http://airshipsonline.com/airships/hma23/index.html|publisher=Airship Heritage Trust|title= HMA 23 |access-date=3 March 2014}}</ref> The triangular section exterior keel had a widened section amidships incorporating a bomb bay, sleeping quarters, radio room and toilet.<ref name="Mowthorp 1995, pp. 127">Mowthorp 1995, pp. 127</ref> Three gondolas were suspended from the keel.  The forward gondola contained the control room and one engine driving a pair of swivelling propellers, a second amidships contained two engines each driving a fixed four-bladed [[pusher configuration|pusher]] propeller on outriggers, and the aft gondola contained the fourth engine driving a single two-bladed [[pusher configuration|pusher]] propeller and an emergency control car.<ref>{{cite journal|journal=[[Flight International|Flight]]|title="23-Class" Rigid  |date=21 August 1919|page=1024  }}</ref> Ballast and fuel were carried in tanks along the keel. [[Rudder]]s and [[Elevator (aircraft)|elevator]]s were of the [[Cruciform tail|cruciform]] type. The design drawings were approved on 10 October 1915.<ref name=H133_5>Higham 1961 pp. 134-5</ref>

==Construction==
Initially three examples were ordered. One was to be built by Vickers at [[Barrow-in-Furness]], Cumbria.  A second, 24r, was ordered from William Beardmore and Company at [[Inchinnan]], in [[Renfrewshire]], Scotland. The third, 25r, was ordered from [[Armstrong-Whitworth]] at [[Barlow, North Yorkshire]].  Many of the components for the ships were built by Beardmore and Armstrong. In December the Treasury approved construction of sixteen more airships, also agreeing on Government loans for the construction of additional construction sheds. One more ship was ordered from Vickers and two from Beardmore and Armstrong. However at this point the Treasury intervened, refusing to allow construction of any more airships until there were sufficient sheds in which to house them.<ref name="Higham 1961, pp. 135"/><ref name=H133_5/>

==Operational history==

===''23r''===
[[File:HMA R 23 Airship With Camel N6814.jpg|thumb|right|23r with Sopwith 2F.1 Camel ''[[United Kingdom military aircraft serial numbers|N6814]]'']]
Construction was begun by Vickers on 1 January 1916. Construction was delayed by material 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.<ref name="Higham 1961, pp. 135"/> The ship was found to have less than the rated lift so the dynamos, bomb gear and furniture were removed to save weight.<ref>Higham 1961, pp. 352</ref> A {{convert|240|hp|abbr=on}} [[Maybach]] engine from the crashed [[Zeppelin]] [[List of Zeppelins#LZ76|''L&nbsp;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. It flew over central London on 6 December, bringing the city to a standstill and generating a wave of patriotic fervour. Despite the airship's 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 [[QF 2 pounder naval gun|2-pounder]] {{convert|40|mm|in|2|abbr=on}} [[British ordnance terms#QF|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 fighter]]s, in the hope that they could defend the airship.<ref>Fitzsimons, p. 521.</ref> First an unmanned, then a manned, [[Sopwith Camel]] were launched successfully.<ref name="Mowthorp 1995, pp. 127"/> 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. It was deleted in September 1919 after a total of about 320 hours.<ref name="Mowthorp 1995, pp. 129">Mowthorp 1995, pp. 129</ref>

[[File:'Rigids' At Pulham, 1918 by John Lavery.jpg|thumbnail|left|upright|Painting of two 23-class airships at Pulham by [[John Lavery]]. Note the tank in the foreground used for ground-handling.]]

===24r===
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&nbsp;lb (680&nbsp;kg) more than its sisters – a difference that was eventually traced to the use of slightly larger and heavier fasteners throughout her structure.<ref name="Mowthorp 1995, pp. 129"/> A solution was required with some urgency, since Beardmore's construction shed needed to be cleared so that work could begin on [[R33 class airship|''R34'']], but the problem was exacerbated by ''24r'' needing all the lift possible to safely navigate the hilly Scottish countryside. Eventually, the decision was taken to completely strip its aft power car, removing the engine and all associated machinery. While this gave ''24r'' more than enough lift, it limited its top speed to 35&nbsp;mph (56&nbsp;km/h).<ref name="Mowthorp 1995, pp. 129"/>

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 immobilised by a headwind, prevented from making any headway at all. It was eventually retired in December 1919 with a total flight time of 164 hours and 40 minutes over a distance of 4,200&nbsp;mi (6,720&nbsp;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]], it was similarly lightened, carrying out its first test flight on 14 October 1917.<ref name="Tapper p94">Tapper 1988, p. 94.</ref> In later flights, another problem emerged:  surging of the gasbags caused sudden and unpredictable movement of the ship's [[center of pressure (fluid mechanics)|centre of pressure]], thereby causing instability. Despite this problem, the airship (by now known as '''R 25''') was officially accepted into service on 23 December 1917,<ref name="Tapper p94"/> and continued in service until September 1919, by which time it had flown 221 hours and 5 minutes and covered 5,909&nbsp;mi (9,454&nbsp;km).

===R.26===
R.26 was the first airship designated under the new system of adding an "R" prefix rather than an "r" suffix for rigids. It had the benefit of being only in the early stages of construction when the weight problems with its sisters were discovered, allowing weight-saving measures to be implemented from the outset. On 4–5 June 1918, it set a new endurance record for the ''23'' class by carrying out a patrol of 40 hours 40 minutes. With ''23r'', it oversaw the surrender of the German [[U-boat]]s at Harwich, before being assigned to experiments in early 1919 to investigate the practicalities of mooring airships in the open. While promising at first, its envelope was eventually soaked with rain, and the airship was subsequently beaten into the ground by a snowstorm. Although refloated by removing its power cars, the structural damage was found to be too great to warrant repairs, and it was struck off charge on 10 March.<ref>Mowthorp 1995, pp. 130</ref>
<!-- ==Variants== -->

==Operators==
;{{UK}}
*[[Royal Navy]]
<!-- ==Units using this aircraft/Operators (choose)== -->

==Specifications==
{{Aircraft specs
|ref=<ref name=AHT/>
|prime units?=imp
|crew=
|capacity=
|length m=163
|length ft=535
|length in=0
|span m=
|span ft=
|span in=
|dia m=<!-- airships etc -->16
|dia ft=<!-- airships etc -->53
|dia in=<!-- airships etc -->0
|width m=<!-- if applicable -->
|width ft=<!-- if applicable -->
|width in=<!-- if applicable -->
|height m=
|height ft=
|height in=
|wing area sqm=
|wing area sqft=
|volume m3=<!-- lighter-than-air -->27,000
|volume ft3=<!-- lighter-than-air -->942,000
|empty weight kg=
|empty weight lb=
|gross weight kg=
|gross weight lb=
|lift kg=<!-- lighter-than-air -->6,600
|lift lb=<!-- lighter-than-air -->14,600
|eng1 number=4
|eng1 name=[[Rolls-Royce Eagle|Rolls-Royce Eagle V12]]
|eng1 type=
|eng1 kw=<!-- prop engines -->190
|eng1 hp=<!-- prop engines -->250
|eng2 number=
|eng2 type=
|eng2 kw=<!-- prop engines -->
|eng2 hp=<!-- prop engines -->
|max speed kmh=84
|max speed mph=52
|cruise speed kmh=<!-- if max speed unknown -->
|cruise speed mph=<!-- if max speed unknown -->
|range km=
|range miles=
|endurance h=<!-- if range unknown -->
|endurance min=<!-- if range unknown -->
|ceiling m=
|ceiling ft=
|climb rate ms=
|climb rate ftmin=
|armament1=
|armament2=
|armament3=
|armament4=
|armament5=
|armament6=
}}

==See also==
{{aircontent
|related=
*[[R23X-class airship]]
|similar aircraft=
|see also=
*[[Zeppelin]]
}}

==Notes==
{{Reflist}}

==References==
* <cite id=AHT>Airships Heritage Trust, 2006, [http://www.aht.ndirect.co.uk/airships/hma23/index.html Airshipsonline : Airships : HMA 23 Class]</cite>
* 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}}

==External links==
{{Commons category}}

{{Admiralty airships}}
{{Vickers aircraft}}
{{Beardmore aircraft}}
{{Armstrong Whitworth aircraft}}

[[Category:1910s British military trainer aircraft]]
[[Category:Airships of the United Kingdom]]
[[Category:Vickers aircraft]]
[[Category:Beardmore aircraft]]
[[Category:Armstrong Whitworth aircraft|23 class airship]]
[[Category:Aircraft first flown in 1917]]