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{{Short description|British rigid airship destroyed in 1930}}
{{Other uses}}
{{Use dmy dates|date=October 2018}}
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{{Infobox aircraft
  |name = R101
  |logo = <!--ONLY for an individual logo of the aircraft model, (NOT the main manufacturer logo)-->
  |image = R101.jpg
  |image_size=220
  |caption = R101 on the day of its first flight, 14 October 1929<!--image caption; if it isn't descriptive it should be left blank-->
  |aircraft_role = Experimental airship
  |manufacturer = [[Royal Airship Works]]
  |designer = [[V.C. Richmond]]
  |civil_registration = G-FAAW
  |first_flight = 14 October 1929<ref name="Shute77">Shute 1954, p. 77.</ref>
  |last_flight = 4 October 1930<ref>[https://www.aht.ndirect.co.uk/airships/r101/R101%20Passenger%20%20Crew%20List.htm "R101 Passenger List."] {{Webarchive|url=https://web.archive.org/web/20090830231632/http://www.aht.ndirect.co.uk/airships/r101/R101%20Passenger%20%20Crew%20List.htm |date=30 August 2009 }} ''Airship Heritage Trust'' via ''Airshipsonline.'' Retrieved: 27 August 2010.</ref>
  |fate = Crashed and burnt out 5 October 1930
  |introduction = <!--date the aircraft entered or will enter military or revenue service-->
  |retired = <!--date the aircraft left military or revenue service. If vague or multiples, it probably should be skipped-->
  |status = <!--in most cases, this field is redundant; use it sparingly-->
  |service = <!--please list only one user – for military aircraft, the user is a nation or a service arm.
                  Do NOT add those tiny flags as they limit horizontal space.-->
  |produced = <!--years in production, e.g. 1970-1999, if still in active use but no longer built-->
  |number_built = 1
  |developed_from = <!-- the aircraft which formed the basis for the topic type -->
}}

'''R101''' was one of a pair of British [[rigid airship]]s completed in 1929 as part of the [[Imperial Airship Scheme]], a British government programme to develop civil airships capable of service on long-distance routes within the [[British Empire]]. It was designed and built by an [[Air Ministry]]–appointed team and was effectively in competition with the government-funded but privately designed and built [[R100]]. When built, it was the world's largest flying craft<ref name="PopSci">{{cite book|title=Popular Science Monthly: Keeping Pace with Aviation|url=https://books.google.com/books?id=2ikDAAAAMBAJ|year= 1930|publisher=Bonnier Corporation|page=41}}</ref> at {{convert|731|ft|m|abbr=on}} in length, and it was not surpassed by another hydrogen-filled rigid airship until the [[LZ 129 Hindenburg|LZ 129 ''Hindenburg'']] was launched seven years later.

After trial flights and subsequent modifications to increase lifting capacity, which included lengthening the ship by {{convert|46|ft|m|abbr=on}} to add another gasbag,<ref name="aht">[http://www.airshipsonline.com/airships/r101/index.html "R101".] Airship Heritage Trust via Airshipsonline.com. Retrieved: 23 July 2008.</ref> the R101 crashed in France during its maiden overseas voyage on 5 October 1930, killing 48 of the 54 people on board.<ref>''Report of the R101 Inquiry'' 1931, p. 7.</ref> Among the passengers killed were [[Christopher Thomson, 1st Baron Thomson|Lord Thomson]], the Air Minister who had initiated the programme, senior government officials, and almost all the dirigible's designers from the [[Royal Airship Works]].

The crash of R101 effectively ended British airship development, and it was one of the worst [[List of airship accidents|airship accidents]] of the 1930s. The loss of 48 lives was more than the 36 killed in the better-known [[Hindenburg disaster|''Hindenburg'' disaster]] of 1937, though fewer than the 52 killed in the French military ''[[Dixmude (airship)|Dixmude]]'' in 1923 and the 73 killed when the [[USS Akron (ZRS-4)#The crash of the Akron|USS ''Akron'']] crashed in the Atlantic Ocean off the coast of [[New Jersey]] in 1933.

==Background==
{{Main|Imperial Airship Scheme}}
R101 was built as part of a British government initiative to develop [[airship]]s to provide passenger and mail transport from Britain to the most distant parts of the [[British Empire]], including [[British India|India]], [[History of Australia (1901–1945)#The 1920s|Australia]] and [[Canada in the World Wars and Interwar Years|Canada]], since the distances were then too great for heavier-than-air aircraft. The [[Dennistoun Burney|Burney]] Scheme of 1922 had proposed a civil airship development programme to be carried out by a specially established subsidiary of [[Vickers Limited|Vickers]] with the support of the British government. The scheme drew support from the [[Air Ministry]], which sought more airships and a base in India. The [[Admiralty (United Kingdom)|Admiralty]] added that it would forgo some [[light cruiser]]s of which it was very short. However, [[Prime Minister of the United Kingdom|Prime Minister]] [[Lloyd George]]'s government decided it could not afford to support the Burney Scheme.<ref>Higham 1961, pp. 283–84.</ref>

When the [[1923 United Kingdom general election|1923 general election]] brought [[Ramsay MacDonald]]’s [[Labour Party (UK)|Labour]] administration to power, the new Air Minister, [[Christopher Thomson, 1st Baron Thomson|Lord Thomson]], formulated the Imperial Airship Scheme in place of the Burney Scheme.<ref>Masefield 1982, p. 30.</ref> It 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 a Vickers subsidiary, the Airship Guarantee Company, under a [[fixed-price contract]]. They were nicknamed the "[[Socialism|Socialist]] Airship" and the "[[Capitalism|Capitalist]] Airship", respectively.<ref>Philpott, Ian: ''The Royal Air Force – Volume 2: An Encyclopedia of the Inter-War Years'', pp. 4–9.</ref>

In addition to the building of the two airships, the Imperial Airship Scheme involved the establishment of the necessary infrastructure for airship operations; for example, the [[mooring mast]]s used at [[Cardington, Bedfordshire|Cardington]], [[Ismalia]], [[Karachi]] and [[Montreal]] had to be designed and built, and the meteorological forecasting network extended and improved.<ref>Sprigg 1931, p. 128.</ref>

Specifications for the airships were drawn up by an Air Ministry committee, whose members included Squadron Leader Reginald Colmore and Lieutenant-Colonel [[Vincent Crane Richmond|V.C. Richmond]],<ref>Masefield 1982, p. 454.</ref> both of whom had extensive experience with airships, most of them non-rigid. They called for airships of not less than five million cubic feet (140,000 m³) capacity and a fixed structural weight not to exceed 90 tons, giving a "disposable lift" of nearly 62 tons. With the necessary allowance of about 20 tons for the service load consisting of a crew of approximately 40, as well as stores and water ballast, this allowed a possible fuel and passenger load of 42 tons.{{citation needed|date=October 2020}} Accommodation for 100 passengers and tankage for 57 hours' flight was to be provided, and a sustainable cruise speed of {{convert|63|mph|km/h|abbr=on}} and maximum speed of {{convert|70|mph|km/h|abbr=on}} were called for.<ref name="R101 Inquiry' 1931, p.14">''Report of the R101 Inquiry'' 1931, p. 14.</ref> In wartime, the airships would be expected to carry 200 troops or possibly five [[parasite aircraft|parasite fighter aircraft]].

Vickers' design team was led by [[Barnes Wallis]], who had extensive experience of rigid airship design and later became famous for the geodetic framework of the [[Vickers Wellington|Wellington bomber]] and for the [[bouncing bomb]]. His principal assistant (the "Chief Calculator"), Nevil Shute Norway, later well known as the novelist [[Nevil Shute]], later gave his account of the design and construction of the two airships in his 1954 autobiography, ''[[Slide Rule: Autobiography of an Engineer]]''. Shute Norway's book characterises R100 as a pragmatic and conservative design, and R101 as extravagant and overambitious, but one purpose of having two design teams was to test different approaches, with R101 deliberately intended to extend the limits of existing technology.<ref>Masefield 1982, p. 111.</ref> Shute Norway later admitted that many of his criticisms of the R101 team were unjustified.<ref>Masefield 1982, pp. 204–05, fn.</ref>

An extremely optimistic timetable was drawn up, with construction of the government-built R101 to begin in July 1925 and be complete by the following July, with a trial flight to India planned for January 1927.<ref>Masefield 1982, p. 51.</ref> In the event, the extensive experimentation that was necessary delayed the start of construction of R101 until early 1927. R100 was also delayed, and neither flew until late 1929.

==Design and development==
[[File:Cardington Shed BW.jpg|thumbnail|One of the [[airship hangar]]s at Cardington]]
The entire airship programme was under the direction of the Director of Airship Development, Group Captain Peregrine Fellowes,<ref>{{cite journal |date=15 January 1915 |title=Royal Air Force Intelligence |url=http://www.flightglobal.com/pdfarchive/view/1925/1925%20-%200035.html |url-status=dead |journal=Flight |volume=17 |issue=3 |pages=35 |archive-url=https://web.archive.org/web/20160306160019/https://www.flightglobal.com/pdfarchive/view/1925/1925%20-%200035.html |archive-date=6 March 2016}}</ref> with Colmore acting as his deputy. Lieutenant-Colonel Richmond was appointed Director of Design: later he was credited as "Assistant Director of Airship Development (Technical)"<ref>''Flight'' 10 October 1930, p. 1126.</ref> with Squadron Leader Michael Rope as his assistant. The Director for Flying and Training, responsible for all operational matters for both airships, was Major [[George Herbert Scott|G.H. Scott]], who had developed the design of the mooring masts that were to be built. Work was based at the [[Royal Airship Works]] at [[Cardington, Bedfordshire|Cardington]], [[Bedfordshire]], which had been built by [[Short Brothers]] during the First World War and had been employed by the Admiralty to copy and improve on the latest German designs from captured rigid airships. The Works had been [[nationalization|nationalised]] in 1919, but after the loss of the [[R38 class airship|R38]] (then in the process of being transferred to the US as ZR2), naval airship development was stopped and it had been placed on a care and maintenance basis.

R101 was to be built only after completion of an extensive research and test programme by the [[National Physical Laboratory, UK|National Physical Laboratory]] (NPL). As part of this programme, the Air Ministry funded the costs of refurbishing and flying [[R33 class airship|R33]] in order to gather data about structural loads and the airflow around a large airship.<ref name="R101 Inquiry' 1931, p.14"/> This data was also made available to Vickers;<ref>[https://api.parliament.uk/historic-hansard/written-answers/1926/may/03/airships#S5CV0195P0_19260503_CWA_33 "Written Answers."] ''[[Hansard]],'' 3 May 1926.</ref> both airships had the same elongated tear-drop shape, unlike previous designs. [[Hilda Lyon]], who was responsible for the aerodynamic development, found that this shape produced the minimum amount of drag.<ref>{{Cite book|url=https://books.google.com/books?id=p8WkkBIeKR4C&q=Hilda+Lyon%2C+Lyon+Shape&pg=PT313|title=Cold War Submarines: The Design and Construction of U.S. and Soviet Submarines|last1=Polmar|first1=Norman|last2=Moore|first2=Kenneth J.|date=2004|publisher=Potomac Books, Inc.|isbn=9781597973199|language=en}}</ref><ref>{{Cite web|url=https://www.wisecampaign.org.uk/inspiration/2016/04/women-in-aviation-the-female-inventor-of-the-lyon-shape|title=Inspiration {{!}} Women in Aviation, the female inventor of the 'Lyon Shape'|last=WISE|website=www.wisecampaign.org.uk|language=en|access-date=18 June 2017|archive-date=25 August 2017|archive-url=https://web.archive.org/web/20170825142816/https://www.wisecampaign.org.uk/inspiration/2016/04/women-in-aviation-the-female-inventor-of-the-lyon-shape|url-status=dead}}</ref> Safety was a primary concern and this would have an important influence on the choice of engines.

[[File:R101-framework.jpg|thumb|left|R101 under construction]]
An early decision had been made to construct the primary structure largely from stainless steel rather than lightweight alloys such as [[duralumin]]. The design of the primary structure was shared between Cardington and the aircraft manufacturer [[Boulton & Paul Ltd|Boulton and Paul]], who had extensive experience in the use of steel and had developed innovative techniques for forming steel strip into structural sections. Working to an outline design prepared with the help of data supplied by the NPL, the stress calculations were performed by Cardington. This information was then supplied to [[John Dudley North|J.D. North]] and his team at Boulton and Paul, who designed the metalwork.<ref>[http://www.flightglobal.com/pdfarchive/view/1928/1928%20-%201105.html "Division of the Design Work."] ''[[Flight International|Flight]],'' 29 November 1928.</ref> The individual girders were fabricated by Boulton and Paul in [[Norwich]], and transported to Cardington where they were bolted together. This scheme for a prefabricated structure entailed demanding manufacturing tolerances and was entirely successful, as the ease with which R101 was eventually extended bears witness. Before any contracts for the metalwork were signed, an entire bay consisting of a pair of the 15-sided transverse ring frames and the connecting longitudinal girders was assembled at Cardington. After the assembly had passed loading tests, the individual girders were then tested to destruction. The structure of the airframe was innovative: the ring-shaped transverse frames of previous airships had been braced by radial wires meeting at a central hub, but no such bracing was used in R101, the frames being stiff enough in themselves.<ref>[http://www.flightglobal.com/pdfarchive/view/1928/1928%20-%201104.html "His Majesty's Airship R100: The construction of R101."]''[[Flight International|Flight]] (supplement),'' 29 November 1928, p. 88. {{Webarchive|url=https://web.archive.org/web/20121105162803/http://www.flightglobal.com/pdfarchive/view/1928/1928%20-%201104.html |date=5 November 2012 }}</ref> However, this resulted in the structure extending further into the envelope, thereby limiting the size of the gasbags.

The specifications drawn up in 1924 by the Committee for the Safety of Airships had based weight estimates on the then-existing rules for airframe strengths. However, the Air Ministry Inspectorate introduced a new set of rules for airship safety standards in late 1924 and compliance with these as-yet unformulated rules had been explicitly mentioned in the individual specifications for each airship.<ref>Masefield 1982, p. 457.</ref> These new rules called for all lifting loads to be transmitted directly to the transverse frames rather than being taken via the longitudinal girders.<ref>Morpurgo 1982, pp. 132–33.</ref> The intention behind this ruling was to enable the stressing of the framework to be fully calculated, rather than relying on [[empirical]]ly accumulated data, as was contemporary practice at the [[Zeppelin]] design office. Apart from the implications for the airframe weight, one effect of these regulations was to force both teams to contrive a new system of harnessing the gasbags. R101's patented "parachute" gasbag harnessing, designed by Michael Rope, proved less than satisfactory, permitting the bags to surge unduly, particularly in rough weather.<ref>''Report of the R101 Inquiry'' 1931, pp. 39–40.</ref>{{failed verification|date=October 2020}} This caused the gasbags to chafe against the structure, tearing holes in the fabric. Another effect was that both R100 and R101 had a relatively small number of longitudinal girders in order to simplify the stress calculations.{{citation needed|date=October 2020}}

R101 used [[Aircraft dope|pre-doped]] linen panels for much of its covering, rather than lacing undoped fabric into place and then applying dope to shrink it. In order to reduce the area of unsupported fabric in the covering, the design alternated the main longitudinals with non-structural "reefing booms" mounted on kingposts which were adjustable using [[jackscrew|screw-jacks]] in order to tension the covering.<ref>Masefield 1982, p. 470.</ref> The pre-doped fabric proved unsatisfactory from the start, with panels splitting because of humidity changes before the airship had even left its shed.<ref name="R101 p. 31">''Report of the R101 Inquiry'' 1931, p. 31.</ref>

There were other innovative design features. Previously, ballast containers had been made in the form of leather "trousers", and one or other leg could be opened at the bottom by a cable-release from the control car. In R101, the extreme forward and aft ballast bags were of this type, and were locally operated, but the main ballast was held in tanks connected by pipes so that ballast could be transferred from one to another to alter the airship's trim using compressed air.<ref>[http://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201317.html "R101."]''[[Flight International|Flight]],'' 29 November 1929, p. 1094. {{Webarchive|url=https://web.archive.org/web/20120321022853/http://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201317.html |date=21 March 2012 }}</ref> The arrangement for ventilating the interior of the envelope, necessary both to prevent any build-up of escaped [[hydrogen]] and also to equalise pressure between the outside and inside, was also innovative. A series of flap-valves were situated at the nose and stern of the airship cover (those at the nose are clearly visible in photographs) to allow air to enter when the airship was descending, while a series of vents was arranged around the circumference amidships to allow air to exit during ascent.<ref name="R101 p. 31"/>

===Engines===
[[File:Beardmore Tornado diesel engine from R101.JPG|thumbnail|Beardmore Tornado engine on display in the [[Science Museum (London)|Science Museum]] in London]]
Heavy oil ([[Diesel engine|diesel]]) engines were specified by the Air Ministry because the airship was intended for use on the India route, where it was thought that high temperatures would make petrol an unacceptable fire hazard because of its low [[flash point]]. A petrol explosion had been a major cause of fatalities in the loss of R38 in 1921.<ref name="norfolkancestors.org">{{usurped|1=[https://web.archive.org/web/20091109035356/http://www.norfolkancestors.org/boulton/r101.htm "Boulton and Paul – the R101."]}} ''norfolkancestors.org.'' Retrieved: 27 August 2010.</ref>

Initial calculations were based on the use of seven [[Beardmore Typhoon]] six-cylinder heavy-oil engines which were expected to weigh {{convert|2,200|lb|kg|abbr=on}} and deliver {{convert|600|bhp|kW|abbr=on}} each.<ref>Masefield 1982, p. 464.</ref> When the development of this engine proved impractical, the use of the eight-cylinder [[Beardmore Tornado]] was proposed instead. This was an engine being developed by [[William Beardmore and Company|Beardmore]], combining two four-cylinder engines which had originally been developed for railway use. In March 1925 these were expected to weigh {{convert|3,200|lb|kg}} and deliver {{convert|700|bhp|kW|abbr=on}} each. Because of the increased weight of each engine, it was decided to use five, resulting in overall power being reduced from {{convert|4,200|bhp|kW|abbr=on}} to {{convert|3,500|bhp|kW|abbr=on}}.{{citation needed|date=October 2020}}

Severe [[mechanical resonance|torsional resonance]] of the [[crankshaft]] was encountered above 950 rpm, limiting the engine to a maximum of 935 rpm, giving an output of only {{convert|650|bhp|kW|0|abbr=on}} with a continuous power rating at 890 rpm of {{convert|585|bhp|kW|0|abbr=on}}.<ref name="Masefield 1982, p. 69">Masefield 1982, p. 69.</ref> The engine was also considerably above estimated weight, at {{convert|4,773|lb|kg|abbr=on}}, over double the initial estimate.<ref name="Masefield 1982, p. 69"/> Some of this excess weight was the result of the failure to manufacture a satisfactory lightweight aluminium crankcase.<ref>''Report of the R101 Inquiry'' p. 37</ref>

The original intention had been to fit two of the engines with variable-pitch propellers in order to provide [[reverse thrust]] for manoeuvring during docking. The torsional resonance caused the hollow metal blades of the reversing propellers to develop cracks near the hubs,<ref>''The Engineer'', October 1930</ref> and as a short-term measure, one of the engines was fitted with a fixed-pitch reverse propeller, consequently becoming dead weight under normal flight conditions.{{#tag:ref|This decision to incorporate a single-purpose engine astonished Shute and the other engineers on the R100 team.<ref name="Shute 74">Shute 1954, p. 74.</ref>|group=N}} For the airship's final flight, two of the engines were adapted to be capable of running in reverse by a simple modification of the [[camshaft]].<ref>{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201140.html |title=R101 Has Two Reversible Engines |magazine=[[Flight International|Flight]] |date=26 September 1930 |number=1135 |volume=XXII |page= 1076 |archive-url=https://web.archive.org/web/20131217224403/http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201140.html |archive-date=17 December 2013 }}</ref>

Each engine car also contained a {{convert|40|bhp|kW|0|abbr=on}} [[Harry Ricardo|Ricardo]] petrol engine for use as a starter motor. Three of these also drove generators to provide electricity when the airship was at rest or flying at low speeds: at normal flight speeds the generators were driven by constant-speed variable-pitch [[Ram air turbine|windmill]]s. The other two auxiliary engines drove compressors for the compressed air fuel and ballast transfer system. Before the final flight, one of the petrol engines was replaced by a Beverly heavy oil engine; to lessen the risk of fire, the petrol tanks could be jettisoned.<ref>[http://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201318.html "R101."] ''[[Flight International|Flight]],'' 11 October 1929, p. 1095.</ref>

Diesel fuel was contained in tanks in the transverse frames, the majority of the tanks having a capacity of {{convert|224|impgal|L|0|abbr=on}}. A mechanism was provided for dumping fuel directly from the tanks in an emergency. By the use of tankage provided for weight compensation, when travelling with a light passenger load a total fuel load of {{convert|10000|impgal|L|abbr=on}} could be carried.<ref>''Flight'' 11 October 1929, pp. 1093–94.</ref>

===Crewing and control===
In normal service, R101 carried a crew of 42. This consisted of two [[Watch system|watches]] of 13 men under the officer of the watch, this duty being divided among the three principal [[ship's officer]]s. In addition there were the chief [[navigator]], the meteorological officer, the chief [[coxswain]], the [[chief engineer]], the chief wireless officer and the chief [[Flight attendant|steward]], who were not assigned to watches but were on duty as necessary, and four supernumeraries (three engineers and a radio operator) who were available to provide relief watch keeping if necessary, and an assistant steward, a cook and a [[galley (kitchen)|galley]] boy who were on duty as required between 06:30 and 21:30.<ref>Masefield 1982, pp. 517–19.</ref> The minimum crew requirement, as specified in the airship's [[Airworthiness certificate|Certificate of Airworthiness]], was 15 men.

The control car was occupied by the duty officer of the watch and the steering and altitude coxswains, who respectively controlled the [[rudder]] and [[elevator (aeronautics)|elevators]] using wheels similar to a [[ship's wheel]]. The engines were individually controlled by an engineer in each of the engine cars, orders being given by an individual [[Engine order telegraph|telegraph]] to each car. These moved an indicator in the engine car to signal the desired throttle setting and also rang a bell to draw attention to the fact that an order had been transmitted.{{citation needed|date=October 2020}}

===Accommodation===
The passenger accommodation was spread over two decks within the envelope and as first designed included 50 passenger cabins for one, two, or four people, a dining room for 60 people,{{citation needed|date=October 2020}} two [[promenade deck]]s with windows down the sides of the airship, a spacious lounge of {{convert|5500|sqft|m2|sigfig=2}}<ref name="PopSci"/> and an [[asbestos]]-lined [[smoking room]] for 24 people. Most of the passenger space was on the upper deck, with the smoking room, kitchen and washrooms, crew accommodation, as well as the chart room and radio cabin on the lower deck.<ref name="aht interior">[http://www.airshipsonline.com/airships//interior/R101Interior.htm "Airships: R101 Interior."] ''Airship Heritage Trust'' via ''Airshipsonline.com.'' Retrieved: 27 August 2010.</ref> The control car was immediately under the forward section of the lower deck and was reached by a ladder from the chart room.{{citation needed|date=October 2020}}

Walls were made of doped linen painted in white and gold. Weight-saving measures included [[wicker]] furniture and aluminium cutlery. The promenade windows were lightweight "[[Cellulose acetate|Cellon]]" instead of the intended glass, and one set was removed as part of later weight-saving measures.{{citation needed|date=October 2020}}

==Operational history==
===Testing===
====1929====
[[File:R101 in flight.jpg|thumb|alt=R101 airship in flight|R101 in flight]] 
The lengthy process of inflating the R101's hydrogen gasbags began on 11 July 1929 and was complete by 21 September. With the airship now airborne and loosely tethered within the shed, it was now possible to carry out lift and trim trials. These were disappointing. A design conference held on 17 June 1929 had estimated a gross lift of 151.8 tons and a total airframe weight, including the power installation, of 105 tons. The actual figures proved to be a gross lift of 148.46 tons and a weight of 113.6 tons.<ref>Masefield 1982, pp. 475–76.</ref> Moreover, the airship was tail-heavy, a result of the tail surfaces being considerably above estimated weight. In this form, a flight to India was out of the question. Airship operations under tropical conditions were made more difficult by the loss of lift in high air temperatures: the loss of lift in [[Karachi]] (then part of British India) was estimated to be as much as 11 tons for an airship the size of R101.<ref>Masefield 1982, p. 293.</ref>

On 2 October the press were invited to Cardington to view the finished airship.<ref>Masefield 1982, pp. 109–14</ref> However, weather conditions made it impossible to take it out of the shed until 12 October, when it was walked out by a ground-handling party of 400. The event attracted a huge number of spectators, with surrounding roads a solid line of cars. The moored airship continued to attract spectators, and it was estimated that more than a million people had made the trip to Cardington to see R101 at the mast by the end of November.<ref name=M132>Masefield 1982, pp. 131–32</ref>

The flying programme was influenced by the Air Ministry's need to generate favourable publicity, illustrating the political pressures which weighed upon the programme. Noël Atherstone, the first officer, commented in his diary on 6 November: "All these window-dressing stunts and joy-rides before she has got an [[Certificate of airworthiness|Airworthiness Certificate]] are quite wrong, but there is no-one in the RAW [Royal Airship Works] executive who has got the guts to put their foot down and insist on trials being free of joy-rides".<ref>Swinfield 2012, p. 262</ref> Atherstone's remarks were occasioned by a lunch held on the airship for delegates to a conference on empire legislation, but there were several similar occasions.{{citation needed|date=October 2020}}

R101 made its first flight on 14 October. After a short circuit over [[Bedford]], course was set for [[London]], where it passed over the [[Palace of Westminster]], [[St Paul's Cathedral]] and the [[City of London|City]], returning to Cardington after a flight lasting five&nbsp;hours&nbsp;40&nbsp;minutes. During this flight the [[Servomechanism|servos]] were not used, without any difficulty being experienced in controlling the airship.<ref>{{Cite newspaper The Times |title=R101 |date=16 October 1929 |page=14 |issue=45335 |column=C }}</ref> A second flight lasting nine&nbsp;hours 38&nbsp;minutes followed on 18 October, with Lord Thomson among the passengers, after which R101 was briefly returned to the shed to enable some modifications to be made to the starting engines.<ref name=M132/> A third flight lasting seven&nbsp;hours 15&nbsp;minutes was made on 1 November, during which it was flown at full power for the first time, recording a speed of {{convert|68.5|mph|kph|abbr=on}}:<ref>Masefield 1982 p. 133</ref> even at full speed it was not found necessary to use the control servos. During this flight, it circled over [[Sandringham House]], observed by [[George V|King George V]] and [[Mary of Teck|Queen Mary]], flew on to the [[Samuel Hoare, 1st Viscount Templewood|previous Secretary of State for Air's]] country house near [[Cromer]], then to Norwich over Boulton & Paul's works and aerodrome before returning by [[Newmarket, Suffolk|Newmarket]] and [[Cambridge]].<ref>{{Cite newspaper The Times |title=R101 At Full Speed |date=2 November 1929 |page=9 |issue=45350 |column=D }}</ref> On 2 November the first night flight was made, slipping the mast at 20:12 before heading south to fly over London and [[Portsmouth]] before attempting a speed trial over a {{convert|43|mi|km|abbr=on}} circuit over the [[Solent]] and the [[Isle of Wight]]. These trials were frustrated by pipe breakages in the cooling systems of two of the engines, a problem later solved by replacing the aluminium piping with [[copper]]. It returned to Cardington around 09:00, the mooring operation ending in a minor accident, damaging one of the reefing booms at the bow.<ref>Masefield 1982, pp.&nbsp;13–15</ref>

On 8 November, a short flight – purely for [[public relations]] purposes – was made, carrying 40 passengers, including the Mayor of Bedford and various officials. To accommodate this load, the airship was flown with only a partial fuel and ballast load and was inflated to a [[Rigid airship#Construction and operation|pressure height]] of {{convert|500|ft|m|abbr=on}}. In Atherstone's words, it "staggered round the vicinity of Bedford for a couple of hours" before returning to the mast.

Two days later, the wind began to rise and [[gale]]s were forecast. On 11 November, the wind touched {{convert|83|mph|kph|abbr=on}}, with a maximum gust speed of {{convert|89|mph|kph|abbr=on}}. Although the ship's behaviour at the mast gave cause for a good deal of satisfaction, there was nevertheless some cause for concern. The movement of the ship had caused considerable movement of the gasbags, the surging being described by Coxswain "Sky" Hunt as being around four inches (ten&nbsp;cm) from side to side and "considerably more" longitudinally. This caused the gasbags to foul the framework, and the resulting chafing caused the gasbags to be holed in many places.<ref>Masefield 1982 pp. 137–38</ref>

A sixth flight was made on 14 November, to test the modifications that had been made to the cooling system and the repairs to the gasbags, carrying a load of 32 passengers, including 10 [[Member of parliament|MP]]s with a special interest in aviation and a party of Air Ministry officials headed by [[Sefton Brancker|Sir Sefton Brancker]], the Director of Civil Aviation.<ref>Masefield 1982, p. 139</ref>

On 16 November, it had been planned to carry out a demonstration flight for a party of 100 MPs, a scheme that had been suggested by Lord Thomson in the expectation that few would wish to take advantage of the offer; in the event, it was oversubscribed.<ref>Masefield 1982, p. 128</ref> The weather on the day was unfavourable, and the flight was rescheduled. The weather then cleared, and on the following day, R101 slipped the mast at 10:33 to carry out an endurance trial, planned to last at least thirty hours. R101 passed over [[York]] and [[Durham, England|Durham]] before crossing the coast and flying over the North Sea as far north as [[Edinburgh]], where it turned west towards [[Glasgow]]. During the night, a series of turning trials were made over the Irish Sea, after which the airship was flown south to fly over [[Dublin]] (the home town of R101's Captain, [[Carmichael Irwin]]) before returning to Cardington via [[Anglesey]] and [[Chester]]. After some delay in finding Cardington owing to fog, R101 was secured to the mast at 17:14, after a flight lasting 30&nbsp;hours 41&nbsp;minutes. The only technical problem encountered during the flight was with the pump for transferring fuel, which broke down several times, although subsequent examination of the engines showed that one was on the point of suffering a failure of a [[Crankpin#Big end bearings|big end bearing]].<ref>Masefield 1982 pp. 141–45</ref>

The flight for the MPs had been rescheduled for 23 November. With the barometric pressure low, R101 lacked sufficient lift to carry 100 passengers, even though all but a bare minimum of fuel was drained off and the ship lightened by removing all unnecessary stores. The flight was cancelled because of the weather, but not before the politicians had arrived at Cardington: they accordingly embarked and had lunch while the ship rode at the mast, only kept in the air by dynamic lift produced by the {{convert|45|mph|kph|abbr=on}} wind.<ref>Masefield 1982, pp.&nbsp;146–47</ref> Following this, R101 remained at the mast until 30 November, when the wind had dropped enough for it to be walked back into the shed.

While the initial flight trials were being carried out, the design team examined the lift problem. Studies identified possible weight savings of 3.16 tons. The weight-saving measures included deleting twelve of the double-berth cabins, removing the reefing booms from the nose to frame 1 and between frames 13 to 15 at the tail, replacing the glass windows of the observation decks with [[Cellon]], removing two water ballast tanks, and removing the servo mechanism for the rudder and elevators.<ref>Masefield 1982, p. 151.</ref> Letting the gasbags out would gain 3.18 tons extra lift, although Michael Rope considered this unwise,<ref>Masefield 1982, p. 226.</ref> since there were thousands of exposed fixings protruding from the girders; chafing of the gasbags would have to be prevented by wrapping these in strips of cloth. To further increase lift, an extra bay of {{convert|500000|cuft|m3|abbr=on}} capacity could be installed. This would deliver an extra nine tons disposable lift. After much consultation, all these proposed measures were approved in December. Letting out the gasbags and the weight-saving measures were begun. Delivery by Boulton & Paul of the metalwork for the extra bay was expected to take place in June.{{citation needed|date=October 2020}}

====1930====
[[File:R101-at mast.jpg|thumbnail|left|R101 at the mooring mast at Cardington]]
R101's outer cover was also giving cause for concern. An inspection on 20 January 1930 by Michael Rope and J. W. W. Dyer, head of the Fabric Section at Cardington, revealed serious deterioration of the fabric on the top of the airship in areas where rainwater had accumulated, and a decision was made to add reinforcement bands along the whole length of the envelope. Further tests undertaken by Rope showed that its strength had deteriorated alarmingly. The original specified strength for the cover was a breaking strain of 700 lb per foot run (10&nbsp;kN/m): the actual strength of samples was at best 85 lb (1.24&nbsp;kN/m), while the calculated load at a speed of {{convert|76|mph|kph|abbr=on}} was 143 lb per foot run (2.09&nbsp;kN/m). A further inspection of the cover on 2 June found many small tears had developed.<ref>Masefield 1982, p. 206.</ref> An immediate decision was taken to replace the pre-doped cover with a new cover which would be doped after fitting. This would take place following the flights which had been planned for June with the purpose of displaying R101 to the public at the [[Hendon Air Show]];{{citation needed|date=October 2020}} for these flights, the cover would be further reinforced.

Confirmation of the poor state of the cover came on the morning of 23 June, when R101 was walked out of the shed. It had been at the mast for less than an hour in a moderate wind when an alarming rippling movement was observed, and shortly afterwards a {{convert|140|ft|m|abbr=on}} split in the cover appeared on the [[starboard]] side of the airship. It was decided to repair this at the mast and to add more strengthening bands. This was done by the end of the day, but the next day a second, shorter, split occurred. This was dealt with in the same way, and it was decided that if the reinforcing bands were added to the repaired area the scheduled appearance at the Hendon Air Show could be made.<ref>''Report of the R101 Inquiry'' 1931 p. 43</ref>

R101 made three flights in June, totalling 29 hours 34 minutes duration. On 26 June, a short proving flight was made, the controls – no longer servo-operated – being described as "powerful and fully adequate".<ref>Masefield 1982, p. 213.</ref> At the end of this flight, the R101 was found to be "flying heavy" and two tons of fuel oil had to be jettisoned in order to lighten the airship for mooring. This was initially attributed to changes in air temperature during the flight. On the following two days, R101 made two flights, the first to take part in the rehearsal for the RAF display at Hendon and the second to take part in the display itself. These flights revealed a problem with lift, considerable jettisoning of ballast being necessary. During this time, Atherstone was replaced by Captain G.F. Meager, who was normally the [[first officer (aviation)|first officer]] on R100. Meager was "alarmed" by the heaviness of R101, as after 10 hours of flight, R100 would have been considerably light due to fuel consumption. Meager observed that it was the first time he had "the wind up" in an airship.<ref>Meager 1970, p. 190.</ref> He had dropped a ton of ballast, and in order to weigh off the R101 for mooring, Flight Lieutenant Irwin was required to dump 10 tons of water and fuel oil.<ref>Meager 1970, p. 191.</ref><ref>Masefield 1982, p. 221.</ref> An inspection of the gasbags revealed a large number of holes, a result of the letting-out of the gasbags which allowed them to foul projections on the girders of the framework.<ref>Masefield 1982, p. 222.</ref>

When the gasbag restraints were loosened to allow more gas capacity (R101B) it came to the attention of Dr. Eckener. His concern was conveyed to Willy von Meister, the [[Deutsche Zeppelin-Reederei]] representative in the United States, who was visiting [[Luftschiffbau Zeppelin]] at [[Lake Constance]]. Dr. Eckener was concerned that the gas bags would be holed by wearing upon the structure and loss of gas would occur. Von Meister stopped on his way back to the US to visit his mother, and met Lord Thomson to convey Dr. Eckener's offer of technical help. Lord Thomson listened cordially, thanked von Meister, and informed him that padding was being installed which British designers felt would suffice.<ref>Meyer 1991, pp. 200–01.</ref>

Concern was also raised over the possibility of loss of gas through the valves, which were of an innovative design by Michael Rope. Airship valves are intended primarily to vent gas automatically if pressure in the cells rises to the point that the bag might rupture; they are also used to adjust lift for handling. It was suspected that valves could open when the airship rolled heavily or when flapping of the outer cover caused localised low pressure, but after an examination of their operation, F. W. McWade, the Air Inspectorate Department inspector at Cardington, concluded that their operation was satisfactory and they were not likely to have been the cause of any significant loss of gas.<ref>Masefield 1982, p. 228.</ref>

As an experimental aircraft, R101 had been operating under a temporary "Permit to Fly", the responsibility of McWade. On 3 July, bypassing his immediate superior, McWade wrote a letter to the Director of Aeronautical Inspection, Lieutenant-Colonel H. W. S. Outram, expressing his unwillingness to recommend either an extension to the permit or the granting of the full [[Certificate of Airworthiness]] which would be necessary before the airship could fly in the [[airspace]] of other countries. His concern was that the padding on the framework was inadequate to protect the gasbags from chafing, the harnessing having been let out so that they were "hard up against the longitudinal girders", and that any surging of the gasbags would tend to loosen the padding, rendering it ineffective. He also expressed doubts about the use of padding, considering that it made inspection of the airframe more difficult and would also tend to trap moisture, making corrosion more likely.<ref>''Report of the R101 Inquiry'' 1931, p. 50.</ref> Outram, who knew little about airships, reacted to this by consulting Colmore, now Director of Airship Development, from whom he received a reassuring reply. The matter was taken no further.<ref>''Report of the R101 Inquiry'' 1931 p. 51</ref>

R101 entered its shed for the extension on 29 June. At the same time, the gasbags were given a complete overhaul, two of the engines were replaced by the adapted engines capable of running in reverse, and most of the cover was replaced. The original cover was left in place between frames 3 and 5 and in two of the bays at the tail.<ref>Masefield 1982, pp. 301–02.</ref> These parts of the cover had been [[aircraft dope|doped]] after fitting and were therefore thought to be satisfactory, even though an inspection by McWade had found that some areas where reinforcements had been stuck on with a rubber solution were seriously weakened; these areas were further reinforced, using dope as an adhesive.<ref>''Report of the R101 Inquiry'' 1931, p. 93. (fn)</ref>

A schedule was drawn up by the Air Ministry for R101 to undertake the flight to India in early October, to coincide with the [[Imperial Conference]] which was to be held in London. The entire programme was intended to improve communication with the Empire, and it was hoped that the flight would generate favourable publicity for the airship programme. The final trial flight of R101 was originally scheduled for 26 September 1930, but high winds delayed the move from the shed until 1 October. That evening, R101<ref>{{cite web|url=https://www.hinckleypastpresent.org/airshipr101.html|title=The British Airship R101 over Hinckley in 1930|website=www.hinckleypastpresent.org|access-date=26 July 2017|archive-date=15 December 2023|archive-url=https://web.archive.org/web/20231215224425/http://www.hinckleypastpresent.org/airshipr101.html|url-status=dead}}</ref> slipped the mast for its only trial flight before setting off for India. This lasted 16 hours 51 minutes and was undertaken under near-ideal weather conditions; because of the failure of the oil cooler in one engine, it was not possible to carry out full-speed trials. The flight was curtailed in order to prepare the airship for the flight to India.<ref name=r101crash>[http://www.aht.ndirect.co.uk/airships/r101/Crash/R101_Crash.htm "Airships: R101 Crash."] ''Airship Heritage Trust'' via ''Airshipsonline.'' Retrieved: 27 August 2010.</ref>

Despite the lack of full endurance and speed trials, and the fact that a proper investigation of the aerodynamic consequences of the extension had not been fully completed by the NPL, a Certificate of Airworthiness was issued on 2 October, the Inspectorate expressing their complete satisfaction with the condition of R101 and the standards to which the remedial work had been carried out. The certificate was handed over to [[Herbert Carmichael Irwin|H. C. Irwin]], the ship's captain, on the day of its flight to India.<ref>''Report of the R101 Inquiry'' 1931, p. 56.</ref>

==Final flight==
[[File:R101 wreckage.jpg|thumb|left|The wreckage of R101]]
R101 departed from [[Cardington Airfield|Cardington]] on the evening of 4 October 1930 for its intended destination of [[Karachi]], via a refuelling stop at [[Ismaïlia]] in [[History of Egypt under the British|Egypt]], under the command of Flight Lieutenant [[Carmichael Irwin]]. Passengers included [[Christopher Thomson, 1st Baron Thomson|Lord Thomson]], Secretary of State for Air; [[Air Vice Marshal]] [[Sefton Brancker|Sir Sefton Brancker]], Director of Civil Aviation; [[Squadron Leader]] William Palstra, [[Royal Australian Air Force|RAAF]] [[Air Liaison Officer]] to the British Air Ministry; and Director of Airship Development, Reginald Colmore. Representing the designers were Lt. Col. V. C. Richmond and Michael Rope.<ref>[http://www.aht.ndirect.co.uk/airships/r101/R101%20Passenger%20%20Crew%20List.htm "R101 Passenger List."] ''Airship Heritage Trust'' via ''Airshipsonline.'' Retrieved: 27 August 2010.</ref>

The weather forecast on the morning of 4 October was generally favourable, predicting south to south-westerly winds of between 20 and 30&nbsp;m.p.h. (32 and 48&nbsp;km/h) at {{convert|2,000|ft|m|abbr=on}} over northern France, with conditions improving over southern France and the Mediterranean.<ref>Masefield 1982, p. 337.</ref> Although the mid-day forecast indicated some deterioration in the situation, this was not considered to be alarming enough to cancel the planned voyage. A course was plotted which would take R101 over London, Paris and [[Toulouse]], crossing the French coast near [[Narbonne]].{{citation needed|date=October 2020}}

Fine rain was beginning to fall when, at dusk, with all the crew and passengers aboard, R101 readied for departure. Under the illuminating spotlights, the jettisoning of water ballast to bring the airship into trim was clearly visible. Squadron Leader Booth, the commander of R100, was watching the departure from the tower's observation gallery and estimated that two tons had been discharged from the nose and a further ton from the midships tanks.<ref>Masefield 1982, p. 350.</ref> R101 cast off from the mast at 18:36 GMT to a cheer from the crowd which had gathered to witness the event, gently backed from the tower, and, as another ton of ballast was jettisoned, the engines were opened up to about half power and the airship slowly began to climb away, initially heading northeast to fly over Bedford before making a 180° turn to port to pass north of Cardington.{{citation needed|date=October 2020}}

At about 19:06, the duty engineer in the aft engine car reported an apparent oil pressure problem. At 19:16, he shut the engine down, and after a short discussion with the chief engineer, work began to replace the oil gauge, since there was nothing apparently wrong with the engine. With one engine stopped, airspeed was reduced by around {{convert|4|mph|0|abbr=on}} to {{convert|58.7|mph|abbr=on}}<ref name=M373>Masefield 1982, p. 373.</ref>

At 19:19, having flown {{convert|29|mi|km|abbr=on|sigfig=2}} but still only {{convert|8|mi|km|abbr=on}} from Cardington, a course was set for London. At 20:01, R101, by now over [[Potters Bar]], made its second report to Cardington, confirming the intention to proceed via London, Paris and Narbonne, but making no mention of the engine problem. By that point, the weather had deteriorated, and it was raining heavily. Flying around {{convert|800|ft|m|abbr=on}} above the ground, the airship passed over [[Alexandra Palace]] before changing course slightly at the landmark clock tower of the [[Metropolitan Cattle Market]] north of [[Islington]], and thence over [[Shoreditch]] to cross the Thames in the vicinity of the [[Isle of Dogs]], passing over the [[Old Royal Naval College|Royal Naval College]] at [[Greenwich]] at 20:28. The airship's progress, flying with its nose pointing some 30 degrees to the right of its track, was observed by many who braved the rain to watch it pass overhead.<ref name=M373/>

An update of the meteorological situation was received at 20:40.<ref>Masefield 1982, p. 376.</ref> The forecast had deteriorated severely, south-westerly winds of up to {{convert|50|mph|km/h|abbr=on}} with low cloud and rain being predicted for northern France, and similar conditions over central France. That this caused concern on board is demonstrated by the request for more detailed information, which was transmitted at 21:19, by which time R101 was near [[Hawkhurst]], Kent. It is possible that an alternative course was being considered. At 21:35, R101 crossed the English coast near [[Hastings]] and at 21:40 transmitted a progress report back to Cardington, mentioning that recovery of rainwater into the ballast tanks was taking place but again not reporting the engine problem. At 22:56 the aft engine was restarted. By now the wind had risen to about {{convert|44|mph|km/h|abbr=on}} with strong gusts, but a further meteorological report received shortly after the airship had crossed the coast had been encouraging about weather conditions south of Paris.<ref>Masefield 1982, p. 383.</ref>

The French coast was crossed at the Point de St Quentin at 23:36 GMT, around {{convert|20|mi|km|abbr=on}} east of the intended landfall.<ref>Masefield 1982, p. 389.</ref> A new course was set to bring R101 over [[Orly]], based on an estimated wind direction of 245 degrees and speed of {{convert|35|mph|km/h|abbr=on}}. The intended course would have taken R101 four miles west of [[Beauvais]], but the estimated wind speed and direction were inaccurate, as a result of which the R101's track was to the east of its intended course. This error would have become apparent when, at about 01:00, R101 passed over [[Poix-de-Picardie]], a distinctive hilltop town that would have been readily recognisable to the navigation officer, Squadron Leader E. L. Johnston. Accordingly, R101 changed course: the new course would take it directly over the {{convert|770|ft|m|abbr=on}} Beauvais Ridge, an area notorious for turbulent wind conditions.<ref>Masefield 1982, p. 396.</ref>

[[File:R101 Memorial, Cardington, Bedfordshire, England - geograph.org.uk - 528665.jpg|thumbnail|R101 memorial in Cardington]]
At 02:00 the watch was changed, Second Officer Maurice Steff taking over the command from Irwin. R101 was at this point "flying heavy",{{citation needed|date=October 2020}} relying on dynamic lift generated by forward airspeed to maintain altitude, estimated by the [[Board of Inquiry]] as at least {{convert|1000|ft|m|abbr=on}} above the ground.<ref>''Report of the R101 Inquiry'' 1931, p. 81.</ref> At about 02:07, R101 went into a [[descent (aeronautics)|dive]] from which it slowly recovered, probably losing around {{convert|450|ft|m|abbr=on}}.{{citation needed|date=October 2020}} As it did so, Rigger S. Church, who was returning to the crew quarters to come off duty, was sent forward to release the forward emergency ballast bags,<ref name=r101crash/> which were locally controlled. This first dive was steep enough to cause A. H. Leech, the foreman engineer from Cardington, to be thrown from his seat in the smoking room and to wake Chief Electrician Arthur Disley, who was dozing in the switch room next to the chart cabin. As the airship recovered, Disley was roused by Chief Coxswain G. W. Hunt, who then went to the crew quarters, calling out, "We're down, lads" in warning. At the same time, the airship went into a second dive and orders to reduce speed to slow (450 rpm) were received in the engine cars.{{citation needed|date=October 2020}} Before Engineer A. J. Cook, on duty in the left-hand midships engine car, could respond, the airship hit the ground at the edge of a wood outside [[Allonne, Oise|Allonne]], {{convert|2.5|mi|km|0|abbr=on}} southeast of Beauvais, and immediately caught fire. The reason for the order to reduce speed is a matter for conjecture because this would have caused the airship to lose dynamic lift and adopt a nose-down attitude.{{citation needed|date=October 2020}} The subsequent inquiry estimated the impact speed at around {{convert|13|mph|abbr=on}}, with the airship between 15° and 25° nose down.<ref>''Report of the R101 Inquiry''1931, p. 79.</ref>

[[File:R101 memorial Allones.jpg|thumb|upright|Unveiling of the memorial to the victims of the R101 disaster outside [[Allonne, Oise|Allonne]]]]
[[File:R101 (32639637953) (2).jpg|thumb|left|A plaque in the Palace of Westminster commemorating the crash]]
Forty-six of the fifty-four passengers and crew were killed immediately. Church and Rigger W. G. Radcliffe survived the crash but later died in hospital in Beauvais, bringing the total of dead to forty-eight.  Of the six eventual survivors, four (including Cook) were engineers in the engine cars outside the hull; Leech and Disley were the only survivors from within the main cabin.<ref name=r101crash/>

=== Memorials ===
In what was described as "French homage to Britain's dead in the great airship R101 disaster", the dead crew and passengers were transported on [[Limbers_and_caissons|artillery caissons]] through [[Beauvais]] past several thousand onlookers, with an escort of [[Spahi]] cavalry.<ref> ''Chronicle'' 6 October 1930</ref> 

The bodies were then returned to the UK, and on Friday 10 October a memorial service took place at [[St Paul's Cathedral]] while the bodies [[lying in state|lay in state]] in [[Westminster Hall]] at the [[Palace of Westminster]]. Nearly 90,000 people queued to pay their respects: at one time the queue was half a mile long, and the hall was kept open until 00:35 to admit them all.<ref>{{Cite newspaper The Times |title=Lying In State|date=11 October 1930 |page=12 |issue=45641 |column=C}}</ref> The following day, a funeral procession transferred the bodies to [[Euston railway station|Euston station]] through streets crowded with mourners. The bodies were then taken to [[Cardington, Bedfordshire|Cardington]] village for burial in a common grave in the cemetery of St Mary's Church. A monument was later erected,<ref>Latitude and longitude: 52.119524 -000.416366 (visible in Google Earth); see also https://welweb.org/ThenandNow/R-101-2.html</ref> and the scorched [[Royal Air Force roundels|Royal Air Force roundel]] which R101 had flown on its tail is on display, along with a memorial tablet, in the church's nave.<ref>[http://www.bedfordshire.gov.uk/CommunityAndLiving/ArchivesAndRecordOffice/CommunityArchives/Shortstown/TheR101VictimsFuneralAndMemorial.aspx "R101 Victims Funeral and Memorial."] {{webarchive|url=https://web.archive.org/web/20121016222017/http://www.bedfordshire.gov.uk/CommunityAndLiving/ArchivesAndRecordOffice/CommunityArchives/Shortstown/TheR101VictimsFuneralAndMemorial.aspx |date=16 October 2012 }}  ''Bedfordshire.gov.'' Retrieved: 5 October 2012.</ref> On 1 October 1933, the Sunday before the third anniversary of the crash, a memorial<ref>Latitude and longitude:  49°24'16.09"N  &nbsp; 2° 7'19.05"E</ref> to the dead near the crash site was unveiled by the side of [[Route nationale 1]] near Allonne. There is also a memorial marker on the actual crash site.<ref>Latitude and Longitude: 49.390650 002.110709 as stated at https://welweb.org/ThenandNow/R-101-2.html</ref>

The Church of the Holy Family and St Michael, a Roman Catholic church in [[Kesgrave]], Suffolk, was built in 1931 in memory of Squadron Leader Michael Rope, who was a Catholic. Suspended from the nave roof is a model of R101.<ref name="TS-Kesgrave">{{cite web|url=https://taking-stock.org.uk/building/kesgrave-holy-family-and-st-michael/|title=Kesgrave – Holy Family and St Michael|publisher=Catholic Trust for England and Wales and [[English Heritage]]|year=2011|access-date=9 December 2022|archive-url=https://web.archive.org/web/20211020080435/https://taking-stock.org.uk/building/kesgrave-holy-family-and-st-michael/|archive-date=20 October 2021|url-status=live}}</ref>

==Official inquiry==
{{more citations needed section|date=October 2020}}
The Court of Inquiry was led by the [[Liberal Party (UK)|Liberal]] politician [[John Simon, 1st Viscount Simon|Sir John Simon]], assisted by Lieutenant-Colonel [[John Moore-Brabazon, 1st Baron Brabazon of Tara|John Moore-Brabazon]] and Professor [[Charles Inglis (engineer)|C. E. Inglis]].<ref>"R101 Inquiry." ''The Times (London)'', 28 October 1930, p. 14.</ref> The inquiry, held in public, opened on 28 October and spent 10 days taking evidence from witnesses, including Professor [[Leonard Bairstow]] and Dr. Hugo Eckener of the Zeppelin company, before adjourning in order to allow Bairstow and the NPL to perform more detailed calculations based on wind-tunnel tests on a specially made model of R101 in its final form. This evidence was presented over three days ending on 5 December 1930. The final report was presented on 27 March 1931.{{citation needed|date=October 2020}}

The inquiry examined most aspects of the design and construction of R101 in detail, with particular emphasis on the gasbags and the associated harnessing and valves, although very little examination of the problems that had been encountered with the cover was made. All the technical witnesses provided unhesitating endorsement of the airworthiness of the airship prior to its flight to India. An examination was also made of the various operational decisions that had been made before the airship undertook its final voyage.{{citation needed|date=October 2020}}

[[File:R101-crash diagram.png|thumb|left|NPL diagram of possible R101 flight path]] 
The possibility of the crash having been the result of a prolonged loss of gas caused by leakage or loss through the valves was discounted since this explanation did not explain the airship's behaviour during its last moments: moreover the fact that the officers on duty had changed watch routinely implied that there had been no particular cause for alarm a few minutes before the crash. The recent change of watch was considered to be a possible contributory factor to the accident, since the new crew would not have had time to get the feel of the airship.{{citation needed|date=October 2020}} It was also considered most unlikely that the accident had been solely caused by a sudden downdraught. A sudden and catastrophic failure was seen as the only explanation. The inquiry discounted the possibility of structural failure of the airframe. The only major fracture found in the wreckage was at the rear of the new framework extension but it was considered that this had either occurred on impact or more probably been caused by the intense heat of the subsequent fire.{{citation needed|date=October 2020}} 

The inquiry came to the conclusion that a tear had probably developed in the forward cover, this in turn causing one or more of the forward gasbags to fail. Evidence presented by Professor Bairstow showed that this would cause the R101 to become too nose-heavy for the elevators to correct.<ref>{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201524.html |title=R 101 Inquiry |magazine=Flight |date= 12 December 1930 |page= 1446 |access-date= 4 March 2012 |volume= XXII  |number=1102   |archive-url=  https://web.archive.org/web/20180207063003/https://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201524.html |archive-date= 2018-02-07  }}</ref> The want of sufficient altitude was considered by the R101 Enquiry and must be considered given that the aircraft was flying in an area of decreasing atmospheric pressure. The same evening, the ''Graf Zeppelin'' at Frankfurt was reading 400 feet high. A similar error over France would have put the R101 400 feet lower than her intended height.<ref>Higham, Robin. ''The British Rigid Airship, 1908–1931.'' G.T. Foulis & Co Ltd, London, 1961, p. 315</ref> The altimeter could have been corrected while flying across the channel by timing the flare drop before ignition, but over France there was no way to determine altimeter correction. Sightings by observers reporting very low altitudes across France and the belief by the crew that they were at a safe altitude according to the altimeter could both be true. The question of sufficient altitude was considered by the R101 Enquiry but not the attendant issue of altimeter correction.<ref>''Report of the R101 Inquiry'', 1931, p. 90.</ref>{{failed verification|date=October 2020}}

The cause of the fire was not established. Several hydrogen airships had crashed in similar circumstances without catching fire. The inquiry thought that it was most probable that a spark from the airship's electrics had ignited escaping hydrogen, causing an explosion. Other suggestions put forward included the ignition of the [[Calcium phosphide|calcium]] [[Flare (pyrotechnic)|flares]] carried in the control car on contact with water,<ref>Chamberlain 1984, pp. 174–78.</ref> electrostatic discharge or a fire in one of the engine cars, which carried petrol for the starter engines. All that is certain is that it caught fire almost at once and burned fiercely. In the extreme heat, the fuel oil from the wreck soaked into the ground and caught fire; it was still burning when the first party of officials arrived by air the next day.<ref>Leasor 1958, p. 151.</ref>

The inquiry considered that it was "impossible to avoid the conclusion that the R101 would not have started for India on the evening of October 4th if it had not been that matters of public policy were considered as making it highly desirable that she should do so", but considered this to be the result of all concerned being eager to prove the worth of R101, rather than direct interference from above.<ref>''Report of the R101 Inquiry'', 1931, p. 95.</ref>

==Aftermath==
The crash of R101 ended British interest in dirigibles during the pre-war period. [[Thomas William Ward (industrialist)|Thos W Ward Ltd]] of [[Sheffield]] salvaged what they could of the wreckage,<ref>[http://explore.bl.uk/primo_library/libweb/action/search.do?dscnt=0&vl(174399379UI0)=any&frbg=&scp.scps=scope%3A%28BLCONTENT%29&tab=local_tab&dstmp=1351367254523&srt=rank&ct=search&mode=Basic&dum=true&tb=t&indx=1&vl(freeText0)=thos+w+ward+outline+of+progress&vid=BLVU1&fn=search "Outline of Progress, Commemorating 75 Years Industrial Service, 1878–1953, p. 17."] ''explore.bl.uk.'' Retrieved: 27 October 2012.</ref> the work continuing through 1931. Although it was stipulated that none of the wreckage should be kept for souvenirs,<ref>[http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201234.html "Loss of R101."] [[Flight International|''Flight'']], 24 October 1930.</ref> Wards made small dishes impressed with the words "Metal from R101", as they frequently did with the metal from ships or industrial structures on which they had worked.

[[File:Metal From R101 from the Collection of Stuart Lythgoe.png|thumb|Dish made from salvaged metal from R101, created by Thos. W. Ward Ltd, 1931]]

The Zeppelin Company purchased five tons of duralumin from the wreck.<ref name=r101crash/> The airship's competitor, R100, despite a more successful development programme and a satisfactory, although not entirely trouble-free, transatlantic trial flight to Canada and back, was grounded immediately after the R101 crash. For over a year, the R100 remained in its hangar at Cardington whilst the fate of the Imperial Airship programme was decided. In December 1931, the R100 was broken up and sold for scrap.<ref>{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1931/1931%20-%201288.html |title=Breaking Up the R101 |magazine= [[Flight International|Flight]] |number=1198 |volume= XXIII |page= 1210 |date= 11 December 1931 |archive-url=https://web.archive.org/web/20160305160339/http://www.flightglobal.com/pdfarchive/view/1931/1931%20-%201288.html |archive-date=2016-03-05}}</ref>

At the time, the Imperial Airship Scheme was a controversial project because of the large sums of public money involved and because some doubted the utility of airships.<ref>Swinfield 2012, p. 146</ref> Subsequently, there has been controversy about the R101's merits. The extremely poor relationship between the R100 team and both Cardington and the Air Ministry created a climate of resentment and jealousy that may have rankled. Nevil Shute Norway's autobiography was serialised by the ''[[Sunday Graphic]]'' on its publication in 1954 and was misleadingly promoted as containing sensational revelations,<ref>[http://www.flightglobal.com/pdfarchive/view/1954/1954%20-%200562.html "Advertisement."] ''[[Flight International|Flight]],'' 5 March 1954.</ref> and the accuracy of his account is a cause of contention among airship historians.<ref>Swinfield 2012, p. 141</ref> Barnes Wallis later expressed scathing criticism of the design although they may in part reflect personal animosities. Nevertheless, his listing of Richmond's "overweening vanity" as a major cause of the debacle and the fact that he had not designed it as another say little for his objectivity.<ref>Morpurgo 1982, p. 187.</ref>

On 27 November 2014, 84 years after the disaster, [[Angela Smith, Baroness Smith of Basildon|Baroness Smith of Basildon]], together with members of the Airship Heritage Trust, unveiled a memorial plaque to the R101 in [[St Stephen's Chapel|St Stephens Hall]] in the Palace of Westminster.<ref>{{cite web|url=http://airshipsonline.com/news/2014/R101_Memorial.htm|title=Airshipsonline R101 Plaque unveilled|publisher=/airshipsonline.com|access-date=20 January 2015}}</ref>

==In popular culture==
* The ''[[Doctor Who]]'' audio play ''[[Storm Warning (audio drama)|Storm Warning]]'' is set aboard R101 during its voyage, with the [[Eighth Doctor]]'s new companion [[Charley Pollard]] impersonating a crewmember on the airship; her time with the Doctor leaves him conflicted when he realises that historical records suggest that Charley was meant to die on R101 if he had not saved her.<ref name="Thompson2013">{{cite book |last=Thompson |first=Dave |title=Doctor Who FAQ: All That's Left to Know About the Most Famous Time Lord in the Universe |url=https://archive.org/details/doctorwhofaqallt0000thom |url-access=registration |access-date=3 October 2018 |date=2013 |publisher=Applause Theatre & Cinema Books |isbn=978-1480342958 |page=[https://archive.org/details/doctorwhofaqallt0000thom/page/226 226] }}</ref>
* R101 figured prominently in the book ''The Airmen Who Would Not Die'' by [[John G. Fuller]] ({{ISBN|978-0399122644}}), which tells of a purported psychic vision of the disaster years before by medium [[Eileen J. Garrett]], and a seance with the deceased officers after the disaster.<ref>{{Cite magazine |date=21 February 1978 |title=The Airmen Who Would Not Die |author=John G. Fuller |url=https://www.kirkusreviews.com/book-reviews/john-g-fuller-3/the-airmen-who-would-not-die/ |magazine=Kirkus Reviews |language=en-us |access-date=3 October 2018 }}</ref>
* R101 is the subject of the rock opera ("songstory") ''[[Curly's Airships]]'' (2000) by [[Judge Smith]].<ref>{{cite book|url=https://books.google.com/books?id=7ctjc6UWCm4C&q=airships+judge+smith&pg=PT1135|title=The Rough Guide to Rock|first=Peter|last=Buckley|date=2017|publisher=Rough Guides|isbn=978-1843531050|access-date=3 October 2017|via=Google Books}}</ref><ref>{{cite web|url=http://www.allmusic.com/album/curlys-airships-mw0000968263|title=Curly's Airships – Judge Smith – Songs, Reviews, Credits |website=AllMusic|access-date=3 October 2017}}</ref>
* R101 has been featured in the TV series, ''[[Britain's Greatest Machines with Chris Barrie]]'' on the National Geographic Channel.<ref>{{Cite web |url=https://www.natgeotv.com/me/britains-greatest-machines-with-chris/about |title=Britain's Greatest Machines with Chris |website=National Geographic |language=en |access-date=3 October 2018 }}</ref>
* The [[Iron Maiden]] song "[[Empire of the Clouds]]" composed by [[Bruce Dickinson]] and featured on the 2015 album ''[[The Book of Souls]]'', is about the R101 and its final flight.<ref>{{cite web|last1=Lombardelli|first1=Tiphaine|title=Bruce Dickinson (Iron Maiden) : la générosité dans l'âme|url=http://www.radiometal.com/article/bruce-dickinson-iron-maiden-la-generosite-dans-lame,188477|website=Radiometal.com|access-date=12 August 2015|language=fr|date=12 August 2015}}</ref>
* The [[Monty Python]] sketch "Historical Impersonations" features Napoleon ([[Terry Jones]]) as the R101 disaster.<ref>{{cite book |title=The Complete Monty Python's Flying Circus: All the Words |url=https://books.google.com/books?id=x0PbXrxZAxoC&pg=PA170 |access-date=3 October 2018 |volume=1 |year=1989 |publisher=Pantheon Books |isbn=978-0679726470 |page=170}}</ref>
* In [[John Crowley (author)|John Crowley]]'s 1991 novella "[[Great Work of Time]]," the destruction (or non-destruction) of R101 is one of the linchpin events whose occurrence (or non-occurrence) marks a particular branching point of the possible timestream which ends the novel.<ref>{{cite book|first=John |last=Crowley |editor-last=Dozois |editor-first=Gardner |title=The Year's Best Science Fiction: 7th Annual Collection |chapter-url=https://books.google.com/books?id=wVOWGxoDKZwC&pg=PA545 |access-date=3 October 2018 |year=1990 |publisher=St. Martin's Press |isbn=978-0312044527 |page=545 |chapter=Great Work of Time}}</ref>
* The progressive rock band [[Lifesigns (band)|Lifesigns]]' 2017 album ''Cardington'' features both the R101 and its hangar, both on the artwork and on the title track.<ref>{{cite web |url=https://lifesignsmusic.co.uk/album/1226308/cardington |title=CD: Cardington |publisher=Lifesigns |access-date=27 April 2020 }}</ref>

==Specifications (R101 after extension)==
{{Aircraft specs
|ref=
|prime units?=imp
|crew=42 (final flight)<ref>Masefield 1982, p. 517.</ref> (15 minimum)<ref name="Certificate">[http://www.airshipsonline.com/airships/r101/R101%20Cert.pdf "R101 Certificate of Airworthiness, 2 October 1930."] ''airshipsonline.com.''  Retrieved: 4 March 2012.</ref>
|capacity=
|length m=236.8
|length ft=777
|length note= <ref name=aht/>
|length in=0
|span m=
|span ft=
|span in=
|dia m=40
|dia ft=131
|dia in=4<!-- airships etc -->
|dia note=<ref name=aht/>
|width m=<!-- if applicable -->
|width ft=<!-- if applicable -->
|width in=<!-- if applicable -->
|height m=42.67
|height ft=140
|height in=
|height note=including control car<ref>{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201771.html |title=His Majesty's Airship R 100 |magazine=Flight  |date=6 December 1929 |page= 1276  |number=1093 |volume=XXI |archive-date= 5 March 2016  |archive-url=https://web.archive.org/web/20160305165204/http://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201771.html }}</ref>
|volume m3=
|volume ft3=5509753
|volume note=<ref name=aht/>
|empty weight kg=116857
|empty weight lb=257395
|empty weight note=<ref name="Masefield p. 477">Masefield 1982, p. 477.</ref>
|gross weight kg=
|gross weight lb=
|lift kg=
|lift lb=55268
|lift note= <ref name="Masefield p. 477"/>
|more general=
|eng1 number=5
|eng1 name=[[Beardmore Tornado]]
|eng1 type=8-cylinder inline [[Diesel engine|Diesel]] (2 reversing) 
|prop blade number=2<!-- propeller aircraft -->
|prop name=
|prop dia m=<!-- propeller aircraft -->
|prop dia ft=16<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->
|prop dia note=<ref name="Certificate"/>
|eng1 kw=436
|eng1 hp=585
|max speed kmh=114
|max speed mph=71
|max speed note=<ref name=aht/>
|cruise speed kmh=101
|cruise speed mph=63
|range km=6437
|range miles=4000
|endurance h=<!-- if range unknown -->
|endurance min=<!-- if range unknown -->
|ceiling m=
|ceiling ft=
|climb rate ms=
|climb rate ftmin=
}}

==See also==
* [[List of airship accidents]]
* [[RAF Cardington]]

==References==

===Notes===
{{Reflist|group=N}}

===Citations===
{{Reflist|30em}}

===Bibliography===
{{Refbegin|}}
* Chamberlain, Geoffrey. ''Airships: Cardington.'' Lavenham, Suffolk, UK: Terence Dalton Ltd., 1984. {{ISBN|0-86138-025-8|}}.
* Fuller, John G. ''The Airman Who Would Not Die.'' New York: Putnam & Sons, 1979. {{ISBN|978-0-399-12264-4|}}.
* Gilbert, James. ''The World's Worst Aircraft.'' Walton-on-Thames, UK: Michael Joseph, 3rd ed., 1975. {{ISBN|978-0-7181-1269-1|}}.
* Grimwood, Terry. [http://www.kesgrave.org.uk/reference.html?ifrm_reference=http://www.comberenterprises.co.uk/apps/WikkaKCW/History "R101: The Kesgrave Connection" (Essay).] ''kesgrave.org.uk.'' Retrieved: 27 August 2010.
* {{cite book|last=Leasor|first=James|author-link=James Leasor|year=2001|orig-year=1957|title=The Millionth Chance: The Story of the R101|place=London|pages=|publisher=Stratus Books|isbn=978-0-7551-0048-4}} 
* Higham, Robin. ''The British Rigid Airship, 1908–1931.'' G.T. Foulis & Co Ltd, London, UK 1961.
*[[Peter Masefield|Masefield, Peter]]. ''To Ride The Storm: The Story of the Airship R101.'' London: William Kimber, 1982. {{ISBN|0-7183-0068-8|}}.
* Meager, Captain George F. ''My Airship Flights 1915–1930.'' London: William Kimber, 1970. {{ISBN|0-7183-0331-8|}}.
* Morpurgo, J.E. ''Barnes Wallis: A Biography.'' London: Longman, 1982 (2nd ed.). {{ISBN|0-7110-1119-2|}}.
* Meyer, Henry Cord. ''Airshipmen Businessmen and Politics 1890–1940, Smithsonian Institution Press.'' Washington D.C. and London, 1991. {{ISBN|1-56098-031-1|}}.
*{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201305.html |title=R.101 |magazine=[[Flight International|Flight]] |volume= XXI |number= 1085 |date= 11 October 1929 |pages=1088–1095 |archive-url= https://web.archive.org/web/20160305082139/https://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%201305.html |archive-date=2016-03-05 }}
* [https://web.archive.org/web/20120315080821/http://www.bedfordraob.org.uk/r101/pdfs/report_of_r101_inquiry.pdf "Report of the R101 Inquiry."] London: HMSO, 1931. via www.bedfordraob.org.uk
* [[Nevil Shute|Shute, Nevil]]. ''[[Slide Rule: Autobiography of an Engineer]].'' London: William Heinemann, 1954. {{ISBN|1-84232-291-5|}}.
* Pratt, Michel. ''Airships R-100 and R-101''. Quebec, 2018. {{ISBN|978-2981-695659}}.
* Sprigg, C. ''The Airship: Its Design, History, Operation and Future''. London: Samson Low, Marston & Co, 1931.
* Swinfield, John. ''Airship: Design Development and Disaster''. London: Conway, 2012. {{ISBN|978-1844-861385|}}
* Venty, Arthur Frederick and Eugene M. Kolesnik. ''Airship Saga''. Poole, Dorset, UK: Blandford Press, 1982. {{ISBN|978-0-7137-1001-4|}}.
* [[Tom Wintringham|Wintringham, T. H.]] [http://www.marxists.org/archive/wintringham/1930/12/x01.htm "The Crime of R101."] ''Labour Monthly,'' December 1930.
{{Refend}}

==Further reading==

* {{cite book|last1=Gwynne|first1=S. C.|author-link=S. C. Gwynne|title=His Majesty's Airship|date=2023|publisher=Scribner|isbn=978-1-982168-27-8}}
* {{cite book|last1=Hammack|first1=Bill|author-link=William S. Hammack|title=Fatal Flight: The True Story of Britain's Last Great Airship|date=2017|publisher=Articulate Noise Books|isbn=978-1-945441-01-1|url=http://www.engineerguy.com/airship/|access-date=6 February 2018}}
*{{citation |magazine=The Aircraft Engineer (Supplement to Flight) |date=29 November 1928 |url=http://www.flightglobal.com/pdfarchive/view/1928/1928%20-%201103.html |title=Building the structure of R101 |last=Poulsen |first=C M |pages=88–98 (1020e-1020p) |archiveurl=https://web.archive.org/web/20150624045028/http://www.flightglobal.com/pdfarchive/view/1928/1928%20-%201103.html |archive-date=2015-06-24 |number= 1040 |volume=XX  }}
*{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201171.html |title=The Loss of H.M. Airship R101 |magazine=Flight |date=10 October 1930  |number=1137 |volume= XXII |page=1107 |archive-url=    https://web.archive.org/web/20150509231034/http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%201171.html |archive-date=2015-05-09 }}

==External links==
{{Commons category|R101}}

* {{cite web |title=The Deadly Airship Race |date=29 Nov 2019 |accessdate=17 Jun 2022 |author=Tim Harford |format=Audio/Podcast |website=Cautionary Tales Episode 4 |url=https://timharford.com/2019/11/cautionary-tales-ep-4-the-deadly-airship-race/}}
* [http://www.aht.ndirect.co.uk/Links%20page/links.htm The Airship Heritage Trust]
* [https://www.youtube.com/watch?v=KswuNjkw7N8 Britain's Million-Pound Monster Comes to London] – [[Newsreel]] footage of the R101, probably of the test flight on 12 October 1929.
*[http://yourarchives.nationalarchives.gov.uk/index.php?title=R101_Airship_Disaster List of documents held at the National Archives]{{Dead link|date=July 2025 |bot=InternetArchiveBot |fix-attempted=yes }}

{{Admiralty airships}}
{{Aviation accidents and incidents in 1930}}
{{Aviation accidents and incidents in France before 1950}}
{{Authority control}}

[[Category:Airships of the United Kingdom]]
[[Category:Rigid airships]]
[[Category:1930 in France]]
[[Category:1930 in the United Kingdom]]
[[Category:Aviation accidents and incidents in 1930]]
[[Category:Accidents and incidents involving balloons and airships]]