Avro Vulcan

Silhouettes of an early Avro 698 concept and the cancelled Avro 710

The origin of the Vulcan and the other V bombers is linked with early British atomic weapon programme and nuclear deterrent policies. Britain's atom bomb programme began with Air Staff Operational Requirement OR.1001 issued in August 1946. This anticipated a government decision in January 1947 to authorise research and development work on atomic weapons, the U.S. Atomic Energy Act of 1946 (McMahon Act) having prohibited exporting atomic knowledge, even to countries that had collaborated on the Manhattan Project.[3] OR.1001 envisaged a weapon not to exceed 24 ft 2 in (7.37 m) in length, 5 ft (1.5 m) in diameter and 10,000 lb (4,500 kg) in weight. The weapon had to be suitable for release from 20,000 to 50,000 ft (6,100 to 15,200 m).[4]

In January 1947, the Ministry of Supply distributed Specification B.35/46 to UK aviation companies to satisfy Air Staff Operational Requirement OR.229 for "a medium range bomber landplane capable of carrying one 10,000 lb (4,500 kg) bomb to a target 1,500 nautical miles (1,700 mi; 2,800 km) from a base which may be anywhere in the world." A cruising speed of 500 knots (580 mph; 930 km/h) at heights between 35,000 and 50,000 ft (11,000 and 15,000 m) was specified. The maximum weight when fully loaded should not exceed 100,000 lb (45,000 kg). Alternatively, the aircraft was to be capable of carrying a conventional bomb load of 20,000 lb (9,100 kg). The similar OR.230 required a "long range bomber" with a 2,000 nautical miles (2,300 mi; 3,700 km) radius of action with a maximum weight of 200,000 lb (91,000 kg) when fully loaded; this requirement was considered too exacting.[5] A total of six companies submitted technical brochures to this specification, including Avro.[6]

Required to tender by the end of April 1947, work began on receipt of Specification B.35/46 at Avro, led by technical director Roy Chadwick and chief designer Stuart Davies; the type designation was Avro 698. It was obvious to the design team that conventional aircraft could not satisfy the specification; knowing little about high-speed flight and unable to glean much from the Royal Aircraft Establishment (RAE) or the US, they investigated German Second World War swept wing research.{Citation needed|date=February 2021}} The team estimated that an otherwise conventional aircraft, with a swept wing of 45°, would have doubled the weight requirement. Realising that swept wings increase longitudinal stability, the team deleted the tail (empennage) and the supporting fuselage, it thus became a swept-back flying wing with only a rudimentary forward fuselage and a fin (vertical stabilizer) at each wingtip. The estimated weight was now only 50% over the requirement; a delta shape resulted from reducing the wingspan and maintaining the wing area by filling in the space between the wingtips, which enabled the specification to be met.[7] Though Alexander Lippisch is generally credited as the pioneer of the delta wing, Chadwick's team had followed its own logical design process.[8] The initial design submission had four large turbojets stacked in pairs buried in the wing either side of the centreline. Outboard of the engines were two bomb-bays.[7]

In August 1947, Chadwick was killed in the crash of the Avro Tudor 2 prototype and was succeeded by Sir William Farren.[9] Reductions in wing thickness made it impossible to incorporate the split bomb bays and stacked engines, thus the engines were placed side by side in pairs either side of a single bomb-bay, with the fuselage growing somewhat. The wingtip fins gave way to a single fin on the aircraft's centreline.[7] Rival manufacturer Handley Page received a prototype contract for its crescent-winged HP.80 B.35/46 tender in November 1947.[9] Though considered the best option, contract award for Avro's design was delayed whilst its technical strength was established.[10] Instructions to proceed with the construction of two Avro 698 prototypes was received in January 1948.[9] As an insurance measure against both radical designs failing, Short Brothers received a contract for the prototype SA.4 to the less-stringent Specification B.14/46. However the SA.4, later named Sperrin, was not required. In April 1948, Vickers also received authority to proceed with their Type 660 which, although falling short of the B.35/46 Specification, being of a more conventional design would be available sooner. This plane entered service as the Valiant.[11]

The prototype Vulcans (VX777 front, VX770 rear) with four Avro 707s at the Farnborough Air Show in September 1953. The large delta wings of the Vulcan quickly gave it the affectionate nickname of 'Tin Triangle'.[12]

As Avro had no flight experience of the delta wing, the company planned two smaller experimental aircraft based on the 698, the one-third scale model 707 for low-speed handling and the one-half scale model 710 for high-speed handling. Two of each were ordered. However, the 710 was cancelled when it was considered too time-consuming to develop; a high-speed variant of the 707 was designed in its place, the 707A.[13] The first 707, VX784, flew in September 1949 but crashed later that month killing Avro test pilot Flt Lt Eric Esler. The second low-speed 707, VX790, built with the still uncompleted 707A's nose section (containing an ejection seat)[14] and redesignated 707B, flew in September 1950 piloted by Avro test pilot Wg Cdr Roland "Roly" Falk. The high speed 707A, WD480, followed in July 1951.[15]

Due to the delay of the 707 programme, the contribution of the 707B and 707A towards the basic design of the 698 was not considered significant,[16] though it did highlight a need to increase the length of the nosewheel to give a ground incidence of 3.5 degrees, the optimum take-off attitude.[17] The 707B and 707A proved the design's validity and gave confidence in the delta planform. A second 707A, WZ736 and a two-seat 707C, WZ744 were also constructed but they played no part in the 698's development.[15]

More influential than the 707 in the 698's design was wind-tunnel testing performed by the RAE at Farnborough, which indicated the need for a wing redesign to avoid the onset of compressibility drag which would have restricted the maximum speed.[18] Painted gloss white, the 698 prototype VX770 flew for the first time on 30 August 1952 piloted by Roly Falk flying solo. The prototype 698, then fitted with only the first-pilot's ejection seat and a conventional control wheel, was powered by four Rolls-Royce RA.3 Avon engines of 6,500 lbf (29 kN) thrust; there were no wing fuel tanks, temporary tankage was carried in the bomb bay.[19] VX770 made an appearance at the 1952 Society of British Aircraft Constructors' (SBAC) Farnborough Air Show the next month when Falk demonstrated an almost vertical bank.[20] After its Farnborough appearance, the future name of the Avro 698 was a subject of speculation; Avro had strongly recommended the name Ottawa,[N 1] in honour of the company's connection with Avro Canada.[10][21] Flight magazine suggested Albion after rejecting Avenger, Apollo and Assegai. The chief of the air staff preferred a V-class of bombers, and the Air Council announced the following month that the 698 would be called Vulcan after the Roman god of fire and destruction.[22] In January 1953, VX770 was grounded for the installation of wing fuel tanks, Armstrong Siddeley ASSa.6 Sapphire engines of 7,500 lbf (33 kN) thrust and other systems; it flew again in July 1953.[23]

Comparison of Vulcan wing designs

The second prototype, VX777, flew in September 1953. More representative of production aircraft, it was lengthened to accommodate a longer nose undercarriage leg, featured a visual bomb-aiming blister under the cabin and was fitted with Bristol Olympus 100 engines of 9,750 lbf (43.4 kN) thrust. At Falk's suggestion, a fighter-style control stick replaced the control wheel. Both prototypes had almost pure delta wings with straight leading edges. During trials in July 1954, VX777 was substantially damaged in a heavy landing at Farnborough. It was repaired and fitted with Olympus 101 engines of 11,000 lbf (49 kN) thrust before resuming trials in October 1955. While exploring the high speed and high altitude flight envelope, mild buffeting and other undesirable flight characteristics were experienced while approaching the speed of sound, including an alarming tendency to enter an uncontrollable dive. This was unacceptable to the Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down. The solution included the "phase 2" wing, featuring a kinked and drooped leading edge and vortex generators on the upper surface, first tested on 707A WD480. An auto-mach trimmer was introduced to give a nose-up pitching moment, but more than was necessary just to counteract the diving tendency, so that the control column had to be pushed rather than pulled to maintain level flight. This artificial pitch-up made the Vulcan appear more like other aircraft as the speed increased.[24]

Meanwhile, the first production B.1,[N 2] XA889, had flown in February 1955 with the original wing.[26] In September 1955, Falk, flying the second production B.1 XA890, amazed crowds at the Farnborough Air Show by executing a barrel roll[27] on his second flypast in front of the SBAC president's tent. After two days flying, he was called in front of service and civil aviation authorities and ordered to refrain from carrying out this "dangerous" manoeuvre.[27] Now fitted with a phase 2 wing, XA889 was delivered in March 1956 to the A&AEE for trials for the type's initial Certificate of Airworthiness which it received the following month.[28]

The first 15 B.1s were powered by the Olympus 101. Many of these early examples in a metallic finish remained the property of the Ministry of Supply being retained for trials and development purposes. Those entering RAF service were delivered to No 230 Operational Conversion Unit (OCU), the first in July 1956.[29] Later aircraft, painted in anti-flash white and powered by the Olympus 102 with 12,000 lbf (53 kN) thrust, began to enter squadron service in July 1957.[30] The Olympus 102s were quickly modified to the Olympus 104 standard, ultimately rated at 13,500 lbf (60 kN) thrust.[31] As far back as 1952, Bristol Aero Engines had begun development of the BOl.6 (Olympus 6) rated at 16,000 lbf (71 kN) thrust[32] but if fitted to the B.1, this would have re-introduced the buffet requiring further redesign of the wing.[33]

The decision to proceed with the B.2 versions of the Vulcan was made in May 1956, being developed by Avro's chief designer Roy Ewans. It was anticipated that the first B.2 would be around the 45th aircraft of the 99 then on order.[34] As well as being able to achieve greater heights over targets, it was believed that operational flexibility could be extended by the provision of in-flight refuelling equipment and tanker aircraft.[35] The increasing sophistication of Soviet air defences required the fitting of ECM equipment and vulnerability could be reduced by the introduction of the Avro Blue Steel stand-off missile, then in development.[36] In order to develop these proposals, the second Vulcan prototype VX777 was rebuilt with the larger and thinner phase 2C wing, improved flying control surfaces and Olympus 102 engines, first flying in this configuration in August 1957.[37] Plans were in hand to equip all Vulcans from the 16th aircraft onwards with in-flight refuelling receiving equipment.[38] A B.1, XA903, was allocated for Blue Steel development work. Other B.1s were used for the development of the BOl.6 (later Olympus 200), XA891; a new AC electrical system, XA893; and ECM including jammers within a bulged tail-cone and a tail warning radar, XA895.[39]

Avro Vulcan B.2 XH533, the first B.2 Vulcan, flying at Farnborough in 1958

The 46th production aircraft and first B.2, XH533, first flew in September 1958 fitted with Olympus 200 engines, six months before the last B.1 XH532 was delivered in March 1959.[40] Rebuilding B.1s as B.2s was considered but rejected over cost. Nevertheless, to extend the B.1's service life, 28 were upgraded by Armstrong Whitworth between 1959 and 1963 to the B.1A standard, including features of the B.2 such as ECM equipment,[41] in-flight refuelling receiving equipment,[42] and UHF radio.[43] The second B.2, XH534, flew in January 1959. Powered by production Olympus 201s with 17,000 lbf (76 kN) thrust, it was more representative of a production aircraft, being fitted with an in-flight refuelling probe and a bulged ECM tail cone. Some subsequent B.2s were initially lacking probes and ECM tail cones, but these were fitted retrospectively. The first 10 B.2s outwardly showed their B.1 ancestry, retaining narrow engine air intakes. Anticipating even more powerful engines, the air intakes were deepened on the 11th (XH557) and subsequent aircraft. Many of the early aircraft were retained for trials and it was the 12th B.2, XH558, that was the first to be delivered to the RAF in July 1960. Coincidentally, XH558 would also be the last Vulcan in service with the RAF, before being retired in 1992.[44]

The 26th B.2, XL317, the first of a production batch ordered in February 1956, was the first Vulcan, apart from development aircraft, capable of carrying the Blue Steel missile; 33 aircraft were delivered to the RAF with these modifications.[45] When the Mk.2 version of Blue Steel was cancelled in favour of the Douglas GAM-87 Skybolt air-launched ballistic missile in December 1959,[46] fittings were changed in anticipation of the new missile, one under each wing. Though Skybolt was cancelled in November 1962, many aircraft were delivered or retrofitted with "Skybolt" blisters.[47] Later aircraft were delivered with Olympus 301 engines with 20,000 lbf (89 kN) thrust. Two earlier aircraft were re-engined (XH557 and XJ784) for trials and development work; another seven aircraft were converted around 1963.[48]

The last B.2 XM657 was delivered in 1965 and the type served until 1984. Whilst in service the B.2 was continuously updated with modifications including rapid engine starting, bomb-bay fuel tanks, wing strengthening to give the fatigue life to enable the aircraft to fly at low level (a tactic introduced in the mid-1960s), upgraded navigation equipment, terrain following radar (TFR), standardisation on a common weapon (WE.117) and improved ECM equipment.[49] The B.1As were not strengthened, thus all were withdrawn by 1968.[50] Nine B.2s were modified for a maritime radar reconnaissance (MRR) role[51] and six for an airborne tanker role.[52] An updated bomb rack assembly allowed the carriage of 30 1,000 lb bombs, up from 21[53] and the updated wing profile increased range to 4,000 nm (7,400 km).[54]

Avro Type 718

The Avro 718 was a 1951 proposal for a delta-winged military transport based on the Type 698 to carry 80 troops or 110 passengers. It would have been powered by four Bristol Olympus BOl.3 engines.[55]

Avro Atlantic

The Avro Type 722 Atlantic was a 1952 proposal (announced in June 1953) for a 120-passenger delta-winged airliner based on the Type 698.[55]

Avro Type 732

The Avro 732 was a 1956 proposal for a supersonic development of the Vulcan and would have been powered by 8 de Havilland Gyron Junior engines. Unlike the proposed Avro 721 low-level bomber of 1952 or the Avro 730 supersonic stainless steel canard bomber dating from 1954 (cancelled in 1957 before completion of the prototype), the Type 732 showed its Vulcan heritage.[55]

Vulcan Phase 6 (Vulcan B.3)

Silhouette of the original study for the Vulcan B.3 patrol missile carrier

In 1960, the Air Staff approached Avro with a request into a study for a patrol missile carrier armed with up to six Skybolt missiles capable of a mission length of 12 hours. Avro's submission in May 1960 was the Phase 6 Vulcan, which would have been the Vulcan B.3. The aircraft was fitted with an enlarged wing of 121 ft (37 m) span with increased fuel capacity; additional fuel tanks in a dorsal spine; a new main undercarriage to carry an all-up-weight of 339,000 lb (154,000 kg); and reheated Olympus 301s of 30,000 lbf (130 kN) thrust. An amended proposal of October 1960 inserted a 10 ft 9 in (3.28 m) plug into the forward fuselage with capacity for six crew members including a relief pilot, all facing forwards on ejection seats, and aft-fan versions of the Olympus 301.[56]

Other countries expressed interest in purchasing Vulcans but, as with the other V-bombers, no foreign sales materialised.[57]

Australia

As early as 1954, Australia recognised that the English Electric Canberra was becoming outdated and evaluated aircraft such as the Avro Vulcan and Handley-Page Victor as potential replacements.[58] Political pressure for a Canberra replacement came to a head in 1962; at which point more modern types such as the BAC TSR-2, General Dynamics F-111C, and North American A-5 Vigilante had become available. The RAF would have transferred several V-bombers, including Vulcans, for interim use by the Royal Australian Air Force (RAAF) if they had purchased the TSR-2, but the RAAF selected the F-111C.[59][60][61]

Argentina

In the early 1980s, Argentina approached the UK with a proposal to buy a number of Vulcans. An application, made in September 1981, requested the 'early availability' of a 'suitable aircraft'. With some reluctance, British ministers approved the export of a single aircraft, but emphasised that clearance had not been given for the sale of a larger number. A letter from the British Foreign and Commonwealth Office to the Ministry of Defence in January 1982 stated that little prospect was seen of this happening without ascertaining the Argentine interest and whether such interest was genuine: 'On the face of it, a strike aircraft would be entirely suitable for an attack on the Falklands.'[62] Argentina invaded the Falkland Islands less than three months later, after which a British embargo on the sale of any military equipment was quickly imposed.

Despite its radical and unusual shape, the airframe was built along traditional lines. Except for the most highly stressed parts, the whole structure was manufactured from standard grades of light alloy. The airframe was broken down into a number of major assemblies: the centre section, a rectangular box containing the bomb-bay and engine bays bounded by the front and rear spars and the wing transport joints; the intakes and centre fuselage; the front fuselage, incorporating the pressure cabin; the nose; the outer wings; the leading edges; the wing trailing edge and tail end of the fuselage; and there was a single swept tail fin with a single rudder on the trailing edge.[63]

A five-man crew was accommodated within the pressure cabin on two levels; the first pilot and co-pilot sitting on Martin-Baker 3K (3KS on the B.2) ejection seats whilst on the lower level the navigator radar, navigator plotter and air electronics officer (AEO) sat facing rearwards and would abandon the aircraft via the entrance door.[64][65] The original B35/46 specification sought a jettisonable crew compartment, this requirement was removed in a subsequent amendment, the rear crew's escape system was often an issue of controversy, such as when a practical refit scheme was rejected.[66][67] A rudimentary sixth seat forward of the navigator radar was provided for an additional crew member;[68] the B.2 had an additional seventh seat opposite the sixth seat and forward of the AEO. The visual bomb-aimer's compartment could be fitted with a T4 (Blue Devil) bombsight,[69] in many B.2s this space housed a vertically mounted Vinten F95 Mk.10 camera for assessing simulated low-level bombing runs.[70]

Fuel was carried in 14 bag tanks, four in the centre fuselage above and to the rear of the nosewheel bay and five in each outer wing. The tanks were split into four groups of almost equal capacity, each normally feeding its respective engine, though cross-feeding was possible. The centre of gravity was automatically maintained by electric timers which sequenced the booster pumps on the tanks.[64][71] B.2 aircraft could be fitted with one or two additional fuel tanks in the bomb-bay.[72]

Despite being designed before a low radar cross-section (RCS) and other stealth factors were ever a consideration,[73] a RAE technical note of 1957 stated that of all the aircraft so far studied, the Vulcan appeared by far the simplest radar echoing object, due to its shape: only one or two components contributed significantly to the echo at any aspect, compared with three or more on most other types.[74][N 3]

Aerial view of a Vulcan B.2 in late RAF markings on static display at RAF Mildenhall, 1984

The two prototype Vulcans were finished in gloss white. Early Vulcan B.1s left the factory in a natural metal finish; the front half of the nose radome was painted black, the rear half painted silver. Front-line Vulcan B.1s had a finish of anti-flash white and RAF "type D" roundels. Front-line Vulcan B.1As and B.2s were similar but with pale roundels.[79]

With the adoption of low-level attack profiles in the mid-1960s, B.1As and B.2s were given a glossy sea grey medium and dark green disruptive pattern camouflage on the upper surfaces, white undersurfaces and "type D" roundels. (The last 13 Vulcan B.2s, XM645 onwards, were delivered thus from the factory[80]). In the mid-1970s Vulcan B.2s received a similar scheme with matte camouflage, light aircraft grey undersides, and "low-visibility" roundels. B.2(MRR)s received a similar scheme in gloss; and the front half of the radomes were no longer painted black. Beginning in 1979, 10 Vulcans received a wrap-around camouflage of dark sea grey and dark green[81][82] because, during Red Flag exercises in the US, defending SAM forces had found that the grey-painted undersides of the Vulcan became much more visible against the ground at high angles of bank.[83]

Avro Vulcan Flight Deck

The original Vulcan B.1 radio fit was: two 10-channel VHF transmitter/receivers (TR-1985/TR-1986) and a 24-channel HF transmitter-receiver (STR-18).[84] The Vulcan B.1A also featured a UHF transmitter-receiver (ARC-52).[43] The initial B.2 radio fit was similar to the B.1A[85] though it was ultimately fitted with the ARC-52, a V/UHF transmitter/receiver (PTR-175), and a single-sideband modulation HF transmitter-receiver (Collins 618T).[86]

The navigation and bombing system (NBS) comprised an H2S Mk9 radar and a navigation bombing computer (NBC) Mk1.[84] Other navigation aids included a Marconi radio compass (ADF), GEE Mk3, Green Satin Doppler radar to determine the groundspeed and drift angle, radio and radar altimeters, and an instrument landing system.[84] TACAN replaced GEE in the B.1A[87] and B.2 in 1964. Decca Doppler 72 replaced Green Satin in the B.2 around 1969[88] A continuous display of the aircraft's position was maintained by a ground position indicator (GPI).[88]

Vulcan B.2s were eventually fitted with the twin-gyro free-running gyroscopic heading reference system (HRS) Mk.2, based upon the inertial platform of the Blue Steel missile, which had been integrated into the system when the missile had been carried.[88] With the HRS a navigator's heading unit (NHU) was provided which enabled the navigator plotter to adjust the aircraft heading, through the autopilot, by as little as 0.1 degrees. The B.2 (MRR) was additionally fitted with the LORAN C navigation system.[51]

The original ECM fit of the B.1A and B.2 was: one Green Palm voice communications' jammer; two Blue Diver metric jammers; three Red Shrimp S-band jammers; a Blue Saga passive warning receiver with four aerials (PWR); a Red Steer tail warning radar; and chaff dispensers.[89] The bulk of the equipment was carried in a large extended tail cone, and a flat ECM aerial counterpoise plate mounted between the starboard tailpipes.[90][N 4] Later equipment on the B.2 included: an L band jammer (replacing a Red Shrimp); the ARI 18146 X-band jammer;[92] replacing the Green Palm; the improved Red Steer Mk.2; infra-red decoys (flares); and the ARI 18228 PWR with its aerials that gave a squared top to the fin.[85][93]

Vulcan B.1 XA890 in early silver scheme landing at Farnborough in September 1955 after Roly Falk's "aerobatic" display. Note the lower outer starboard airbrake, which was later deleted.

The aircraft was controlled by a fighter-type control stick and rudder bar which operated the powered flying controls (PFCs). Each PFC had a single electro-hydraulic powered flying control unit (PFCU) except the rudder which had two, one running as a back-up. Artificial feel and autostabilisation in the form of pitch and yaw dampers were provided, as well as an auto mach trimmer.[94]

The flight instruments in the B.1 were traditional and included G4B compasses;[95] Mk.4 artificial horizons;[96] and zero reader flight display instruments.[97] The B.1 had a Smiths Mk10 autopilot.[98] In the B.2, these features were incorporated into the Smiths Military Flight System (MFS), the pilots' components being: two beam compasses; two director-horizons; and a Mk.10A or Mk.10B autopilot.[99] From 1966, B.2s were fitted with the ARI 5959 TFR, built by General Dynamics,[100] its commands being fed into the director-horizons.[101]

The B.1 had four elevators (inboard) and four ailerons (outboard).[102] In the B.2, these were replaced by eight elevons.[103] The Vulcan was also fitted with six electrically operated three-position (retracted, medium drag, high drag) airbrakes, four in the upper centre section and two in the lower.[104] There were originally four lower airbrakes but the outboard two were deleted before the aircraft entered service.[105] A brake parachute was installed inside the tail cone.[106]

The main electrical system on the B.1/B.1A was 112 V DC supplied by four 22.5kW engine-driven starter-generators. Backup power was provided by four 24 V 40 Ah batteries connected in series providing 96 V. Secondary electrical systems were 28 V DC, single-phase 115 V AC at 1600 Hz, and three-phase 115 V AC at 400 Hz, driven by transformers and inverters from the main system. The 28 V DC system was backed up by a single 24 V battery.[107]

For greater efficiency and higher reliability,[108] the main system on the B.2 was changed to three-phase 200 V AC at 400 Hz supplied by four 40 kVA engine-driven constant speed alternators. Engine starting was then by air-starters supplied from a Palouste compressor on the ground. Standby supplies in the event of a main AC failure were provided by a ram air turbine (RAT) driving a 17 kVA alternator that could operate from high altitudes down to 20,000 ft (6,100 m), and an airborne auxiliary power plant (AAPP),[109] a Rover[33] gas turbine driving a 40kVA alternator, which could be started once the aircraft was below an altitude of 30,000 ft (9,100 m). Secondary electrical supplies were by transformer-rectifier units (TRUs) for 28 V DC and rotary frequency converters for the 115 V 1600 Hz single phase supplies.[109]

The change to an AC system was a significant improvement. Each PFCU had a hydraulic pump which was driven by an electric motor.[110] Because there was no manual reversion, a total electrical failure would result in a loss of control. The standby batteries on the B.1 were designed to give enough power for 20 minutes of flying time but this proved to be optimistic and two aircraft, XA891 and XA908, crashed as a result.[111]

The main hydraulic system provided pressure for undercarriage raising and lowering and bogie trim; nosewheel centring and steering; wheelbrakes (fitted with Maxarets); bomb doors opening and closing; and (B.2 only) AAPP air scoop lowering. Hydraulic pressure was provided by three hydraulic pumps fitted to Nos. 1, 2 and 3 engines. An electrically operated hydraulic power pack (EHPP) could be used to operate the bomb doors and recharge the brake accumulators. A compressed air (later nitrogen) system was provided for emergency undercarriage lowering.[112]

The Rolls-Royce Olympus, originally known as the "Bristol BE.10 Olympus",[113][N 5] is a two-spool axial-flow turbojet that powered the Vulcan. Each Vulcan had four engines buried in the wings, positioned in pairs close to the fuselage. The engine's design began in 1947, intended to power the Bristol Aeroplane Company's own rival design to the Vulcan.[115] A serendipitous arrangement in air intakes could cause the Vulcan to emit a distinctive "howl" when the engines were at approximately 90% power,[116] which can be heard as the aircraft performs a flypast, such as at public airshows.[117][118]

Gas-flow diagram of an Olympus Mk 101 engine

As the prototype Vulcan VX770 was ready for flight prior to the Olympus being available, it first flew using Rolls-Royce Avon RA.3 engines of 6,500 lbf (29 kN) thrust. These were quickly replaced by Armstrong Siddeley Sapphire ASSa.6 engines of 7,500 lbf (33 kN) thrust.[119] VX770 later became a flying test bed for the Rolls-Royce Conway.[120] The second prototype VX777 first flew with Olympus 100s of 10,000 lbf (44 kN) thrust. It was subsequently re-engined with Olympus 101 engines.[121] When VX777 flew with a Phase 2C (B.2) wing in 1957, it was fitted with Olympus 102 engines of 12,000 lbf (53 kN) thrust.[122]

Early B.1s were engined with the Olympus 101. Later aircraft were delivered with Olympus 102s. All Olympus 102s became the Olympus 104 on overhaul and ultimately 13,500 lbf (60 kN) thrust on uprating.[123] The first B.2 flew with the second-generation Olympus 200,[124] design of which began in 1952.[125] Subsequent B.2s were engined with either the uprated Olympus 201 or the Olympus 301. The Olympus 201 was designated 202 on being fitted with a rapid air starter.[126] The engine would later be developed into a reheated (afterburning) powerplant for the cancelled TSR-2 strike bomber and the supersonic passenger transport Concorde.[83]

In September 1956, the RAF received its first Vulcan B.1, XA897, which immediately embarked upon a round-the-world tour. The tour was to be an important demonstration of the range and capabilities of the aircraft, but it also had other benefits in the form of conducting goodwill visits in various countries; during their service Vulcans routinely visited various nations and distant parts of the former British Empire as a show of support and military protection.[127] This first tour, however, was struck by misfortune; on 1 October 1956, while landing in bad weather at London Heathrow Airport at the completion of the world tour, XA897 was destroyed in a fatal accident.[128]

A Vulcan B1A of the Waddington Wing at Filton during a public air display in the 1960s

The first two aircraft were delivered to 230 OCU in January 1957 and the training of crews started on 21 February 1957.[111] The first OCU course to qualify was No. 1 Course, on 21 May 1957, and they went on to form the first flight of No. 83 Squadron.[111] No. 83 Squadron was the first operational squadron to use the bomber, at first using borrowed Vulcans from the OCU, and on 11 July 1956 it received the first aircraft of its own.[111] By September 1957, several Vulcans had been handed over to No. 83 Squadron.[129] The second OCU course also formed a Flight of 83 Squadron, but subsequent trained crews were also used to form the second bomber squadron, 101 Squadron.[111] The last aircraft from the first batch of 25 aircraft had been delivered by the end of 1957 to 101 Squadron.[111]

In order to increase the mission range and flight time for Vulcan operations, in-flight refuelling capabilities were added in 1959 onwards; several Valiant bombers were refurbished as tankers to refuel the Vulcans.[130] Continuous airborne patrols proved untenable, however, and the refuelling mechanisms across the Vulcan fleet fell into disuse in the 1960s.[130] Both Vulcans and the other V-force aircraft routinely visited the Far East, in particular Singapore, where a fully equipped nuclear weapons storage facility had been constructed in 1959.[131] These deployments were part of the UK contribution to SEATO operations, often to test the defenses of friendly nations in joint exercises.[131] During the Indonesia–Malaysia confrontation Britain planned to deploy three squadrons of V-bomber aircraft and 48 Red Beard tactical nuclear weapons to the region, although this was ultimately decided against. Vulcans trained in the region for both conventional and nuclear missions.[131] In the early 1970s, the RAF decided to permanently deploy two squadrons of Vulcans overseas in the Near East Air Force Bomber Wing, based at RAF Akrotiri in Cyprus. The Vulcans were withdrawn in the mid-1970s however as Cypriot intercommunal violence intensified.[132]

Royal Air Force Vulcan B.2 being prepared for flight on 25 May 1985

Vulcans flew some very long range missions. In June 1961, one flew 18,507 km from RAF Scampton to Sydney in just over 20 hours, facilitated by three air refuellings. Vulcans frequently visited the United States during the 1960s and 1970s to participate in air shows and static displays, as well as to participate in the Strategic Air Command's (SAC) Annual Bombing and Navigation Competition at such locations as Barksdale AFB, Louisiana and the former McCoy AFB, Florida. Vulcans also took part in the 1960, 1961, and 1962 Operation Skyshield exercises, in which NORAD defences were tested against possible Soviet air attack, the Vulcans simulating Soviet fighter/bomber attacks against New York, Chicago and Washington. The results of the tests were classified until 1997.[133] The Vulcan proved quite successful during the 1974 "Giant Voice" exercise, in which it managed to avoid USAF interceptors.[134]

As part of Britain's independent nuclear deterrent, the Vulcan initially carried Britain's first nuclear weapon, the Blue Danube gravity bomb.[135] Blue Danube was a low-kiloton yield fission bomb designed before the United States detonated the first hydrogen bomb. These were supplemented by U.S.-owned Mk 5 bombs (made available under the Project E programme) and later by the British Red Beard tactical nuclear weapon.[136] The UK had already embarked on its own hydrogen bomb programme, and to bridge the gap until these were ready the V-bombers were equipped with an Interim Megaton Weapon based on the Blue Danube casing containing Green Grass, a large pure-fission warhead of 400-kiloton-of-TNT (1.7 PJ) yield.[137][N 6] This bomb was known as Violet Club.[137] Only five were deployed before the Green Grass warhead was incorporated into a developed weapon as Yellow Sun Mk.1.[137]

The later Yellow Sun Mk 2, was fitted with Red Snow,[137] a British-built variant of the U.S. W28 warhead. Yellow Sun Mk 2 was the first British thermonuclear weapon to be deployed, and was carried on both the Vulcan and Handley Page Victor. The Valiant retained U.S. nuclear weapons assigned to SACEUR under the dual-key arrangements. Red Beard was pre-positioned in Singapore for use by Vulcan and Victor bombers.[140] From 1962, three squadrons of Vulcan B.2s and two squadrons of Victor B.2s were armed with the Blue Steel missile, a rocket-powered stand-off bomb, which was also fitted with the 1.1 Mt (4.6 PJ) yield Red Snow warhead.[141]

Operationally, RAF Bomber Command and the SAC cooperated in the Single Integrated Operational Plan (SIOP) to ensure coverage of all major Soviet targets from 1958; 108 of the RAF's V-Bombers were assigned targets under SIOP by the end of 1959.[142] From 1962 onwards, two jets in every RAF bomber base were armed with nuclear weapons and on standby permanently under the principle of Quick Reaction Alert (QRA).[142] Vulcans on QRA were to be airborne within four minutes of receiving an alert, as this was identified as the amount of time between warning of a USSR nuclear strike being launched and it arriving in Britain.[143] The closest the Vulcan came to taking part in potential nuclear conflict was during the Cuban Missile Crisis in October 1962, where Bomber Command was moved to Alert Condition 3, an increased state of preparedness from normal operations; however, it stood down in early November.[144]

XH558 taking off, 2008 Farnborough Airshow

The Vulcans were intended to be equipped with the Skybolt missile to replace the Blue Steel, with Vulcan B.2s carrying two Skybolts under the wings. The last 28 B.2s were modified on the production line to fit pylons to carry the Skybolt.[145][146] A B.3 variant with increased wingspan to carry up to six Skybolts was proposed in 1960.[147] When the Skybolt missile system was cancelled by U.S. President John F. Kennedy on the recommendation of his Secretary of Defense, Robert McNamara in 1962, precipitating the Skybolt Crisis, Blue Steel was retained. To supplement it until the Royal Navy took on the deterrent role with Polaris ICBM-equipped submarines, the Vulcan bombers adopted a new mission profile of flying high during clear transit, dropping down low to avoid enemy defences on approach, and deploying a parachute-retarded bomb, the WE.177B.[148] However, since the aircraft had been designed for high-altitude flight, at low altitudes it could not exceed 350 knots. RAF Air Vice Marshal Ron Dick, a former Vulcan pilot, said "it is [thus] questionable whether it could have been effective flying at low level in a war against ... the Soviet Union."[149]

After the British Polaris submarines became operational and Blue Steel was taken out of service in 1970, the Vulcan continued to carry WE.177B in a tactical nuclear strike role as part of the British contribution to Europe's standing NATO forces, although they no longer held aircraft at 15 minutes' readiness in peacetime.[148] Two squadrons were also stationed in Cyprus as part of the Near East Air Force and assigned to Central Treaty Organization in a strategic strike role. With the eventual demise of the WE.177B and the Vulcan bombers, the Blackburn Buccaneer, SEPECAT Jaguar, and Panavia Tornado continued with the WE.177C until its retirement in 1998.[150] While not a like-for-like replacement, the multi-role Tornado interdictor/strike bomber is the successor for the roles previously filled by the Vulcan.[151]

Vulcan XM597 at the National Museum of Flight, Scotland; note the Operation Black Buck markings and the small Brazilian flag indicating the aircraft's internment in Brazil.

Engineers and flight crew with the Vulcan prior to deployment in the Falklands

Although in operational use the Vulcan typically carried various nuclear armaments, the type also had a secondary conventional role. While performing conventional combat missions, the Vulcan could carry up to 21 1,000 lb (454 kg) bombs inside its bomb bay.[152] From the 1960s, the various Vulcan squadrons would routinely conduct conventional training missions; the aircrews were expected to be able to perform conventional bombing missions, in addition to the critical nuclear strike mission.[153]

The Vulcan's only combat missions took place towards the end of the type's service in 1982. During the Falklands War, the Vulcan was deployed against Argentinian forces which had occupied the Falkland Islands. The missions performed by the Vulcan became known as the Black Buck raids, each aircraft had to fly 3,889 mi (6,259 km) from Ascension Island to reach Stanley on the Falklands. Victor tankers conducted the necessary air-to-air refuelling for the Vulcan to cover the distance involved; approximately 1,100,000 imp gal (5,000,000 l) of fuel was used in each mission.[154]

Engineering work to prepare the 5 Vulcans which would conduct the missions began on 9 April.[155][156] Each aircraft required modifications to the bomb bay, the reinstatement of the long out-of-use in-flight refuelling system, the installation of a new navigational system derived from the Vickers VC10, and the updating of several onboard electronics. Underneath the wings, new pylons were fitted to carry an ECM pod and Shrike anti-radar missiles at wing hardpoint locations.

A Vulcan flying over Ascension Island on 18 May 1982

On 1 May, the first mission was conducted by a single Vulcan (XM607) that flew over Port Stanley and dropped its bombs on the airfield concentrating on the single runway, with one direct hit, making it unsuitable for fighter aircraft. The Vulcan's mission was quickly followed up by strikes against anti-air installations, flown by British Aerospace Sea Harriers from Royal Navy aircraft carriers.[157] A further two missions saw missiles launched against radar installations and two additional missions were cancelled.[154] At the time, these missions held the record for the world's longest-distance raids.[152][158] The Vulcans' ECM systems proved to be effective at jamming Argentine radars; while a Vulcan was within the theatre, other British aircraft in the vicinity had a reduced chance of coming under effective fire.[159]

On 3 June 1982, Vulcan B.2 XM597 of No. 50 Squadron took part in the "Black Buck 6" mission against Argentinian radar sites at Stanley airfield on the Falkland Islands. While attempting to refuel for its return journey to Ascension Island, the probe broke, leaving the Vulcan with insufficient fuel, forcing a diversion to Galeão Air Force Base, Rio de Janeiro in neutral Brazil. En route, secret papers were dumped along with the two remaining AGM-45 Shrike missiles, although one failed to launch. After a mayday call, the Vulcan, escorted by Brazilian Air Force Northrop F-5 fighters, was permitted an emergency landing at Rio with very little fuel left on board.[160] The Vulcan and her crew were detained until the end of hostilities nine days later.[161]

In November 1973, as a result of the planned closure of the Victor SR.2 equipped No. 543 Squadron, No. 27 Squadron reformed at RAF Scampton equipped with the Vulcan as a replacement in the maritime radar reconnaissance role.[162][N 7] The squadron carried out patrols of the seas around the British Isles, including the strategically important GIUK gap between Iceland and the United Kingdom, flying at high level and using the Vulcan's H2S radar to monitor shipping. In peacetime, this could be followed up by visual identification and photography of targets of interest at low level. In the event of war, a Vulcan would leave visual identification of potential targets to Buccaneers or Canberras, and could coordinate attacks by Buccaneers against hostile shipping.[164] Though initially equipped with a number of B.2 aircraft,[165] the Squadron eventually operated nine B.2 (MRR) aircraft (also known by the unofficial designation SR.2).[51][166] The aircraft were modified for the role by removing the TFR (and its thimble radome) and adding the LORAN C radio navigation aid. The main external visual difference was the presence of a gloss paint finish, with a light grey undersurface, to protect against sea spray.[51]

The squadron also inherited its secondary role of air sampling from No. 543 Squadron.[51] This involved flying through plumes of airborne contamination and using onboard equipment to collect fallout released from both above ground and underground nuclear tests for later analysis at the Atomic Weapons Research Establishment at Aldermaston.[167] Five aircraft had small pylons fitted to the redundant Skybolt hardpoints, which could be used to carry sampling pods modified from drop tanks.[N 8] These pods would collect the needed samples on a filter, while an additional smaller "localiser" pod was fitted to the port wing, inboard of the main pylons.[163][166][168]

The squadron disbanded at Scampton in March 1982, passing on its radar reconnaissance duties to the RAF's Nimrods.[166]

After the end of the Falklands War in 1982, the Vulcan B.2 was due to be withdrawn from RAF service that year.[169] However, the Falklands campaign had consumed much of the airframe fatigue life of the RAF's Victor tankers. While Vickers VC10 tanker conversions had been ordered in 1979[170] and Lockheed TriStar tankers would be ordered after the conflict,[171] as a stopgap measure six Vulcans were converted into single point tankers. The Vulcan tanker conversion was accomplished by removing the jammers from the ECM bay in the tail of the aircraft, and replacing them with a single Hose Drum Unit.[156] An additional cylindrical bomb-bay tank was fitted, giving a fuel capacity of almost 100,000 lb (45,000 kg).[156][172]

The go-ahead for converting the six aircraft was given on 4 May 1982.[173] Just 50 days after being ordered, the first Vulcan tanker, XH561, was delivered to RAF Waddington.[156][173] The Vulcan K.2s were operated by No. 50 Squadron, along with three Vulcan B.2s, in support of UK air defence activities until it was disbanded in March 1984.[174]

Vulcan B.2 in formation with the Red Arrows, 2015

After the disbandment of No. 50 Squadron, two Vulcans continued flying with the RAF in air displays as part of the Vulcan Display Flight, based at Waddington but administered through No. 55 Squadron, based at RAF Marham. Initially displaying using XL426, in 1986 that aircraft was sold, having been replaced by XH558, which began displays in 1985. The VDF continued with XH558 until 1992, finishing operations after the Ministry of Defence determined it was too costly to run in light of budget cuts. Both aircraft subsequently entered preservation and survived, although a third, XH560, kept in reserve in the first years, was later scrapped.

• The first prototype VX770 had its Sapphire engines replaced with four 15,000 lbf (67 kN) Rolls-Royce Conway RCo.7 turbofans in 1957. It was transferred to Rolls-Royce as the Conway test bed.[175] It flew with the Conways, the first turbofans in the world, until its fatal crash in September 1958.[176]
• The first Vulcan B.1 XA889 was used for the flight clearances of the Olympus 102 and 104.[177]
• Vulcan B.1 XA891 was fitted with four Olympus 200 engines in the spring of 1958 for intensive flying trials. The aircraft crashed in July 1958 during a routine test flight.[178]
• Vulcan B.1 XA894 flew with five Olympus engines, the standard four Mk.101s, plus a reheated Olympus 320 destined for the BAC TSR-2 in an underslung nacelle. This aircraft was destroyed in a ground fire at Filton on 3 December 1962.[176]
• Vulcan B.1 XA896 was withdrawn from RAF service in June 1964 and transferred to be converted to the test bed for the Bristol Siddeley BS100 vectored thrust turbofan for the Hawker Siddeley P.1154. The P.1154 was cancelled in February 1965 and XA896 was scrapped before being converted.[179]
• Vulcan B.1 XA902 was withdrawn from RAF service after a landing accident in 1958. After rebuilding, it replaced VX770 as the Conway test bed, fitted with four RCo.11s. The two inner Conways were replaced with Rolls-Royce Speys, flying for the first time in this configuration on 12 October 1961.[176]
• Vulcan B.1 XA903, surplus to Blue Steel trials, was converted to a similar layout to XA894 to flight test the Olympus 593 Concorde installation. The first flight was on 1 October 1966 and testing continued through to June 1971.[180] In April 1973, XA903 started flying with an underslung Rolls-Royce RB.199 turbofan destined for the Panavia Tornado. XA903 was the last B.1 to fly, being retired in February 1979.[181]
• Vulcan B.2 XH557 was used by BSEL for developing the Olympus 301 and first flew with the larger engine in May 1961. It was returned to Woodford in 1964 to be refurbished for the RAF.[182]

A total of 134 production Vulcans were assembled at Woodford Aerodrome, 45 to the B.1 design and 89 were B.2 models, the last being delivered to the RAF in January 1965.[188]

• RAF Akrotiri in Cyprus was the base for two operational B.2 squadrons from 1969 to 1975
  • 9 Squadron 1969–1975, moved from Cottesmore in 1969 it returned to the UK in 1975 to Waddington.[210]
  • 35 Squadron 1969–1975, moved from Cottesmore in 1969 it returned to the UK in 1975 to Scampton.[202]
• RAF Coningsby was the base for three operational squadrons from 1962 to 1964
  • 9 Squadron 1962–1964, formed in 1962 to operate the B.2 it moved to Cottesmore in 1964.[199]
  • 12 Squadron 1962–1964, formed in 1962 to operate the B.2 it moved to Cottesmore in 1964.[200]
  • 35 Squadron 1962–1964, formed in 1962 to operate the B.2 it moved to Cottesmore in 1964.[202]

Avro Vulcans of No 617 Squadron at RAF Cottesmore circa 1975

• RAF Cottesmore was the base for three operational squadrons from 1964 to 1969
  • 9 Squadron 1964–1969, moved in from Coningsby in 1964, it moved to Akrotiri in 1969.[199]
  • 12 Squadron 1964–1967, moved in from Coningsby in 1964 until it disbanded in 1967.[199]
  • 35 Squadron 1964–1969, moved in from Coningsby in 1964, it moved to Akrotiri 1969.[202]
• RAF Finningley
  • 101 Squadron 1957–1961, formed in 1957 to be the second operational B.1 squadron, moved to Waddington in 1961.[206]
  • 230 OCU 1961–1969, moved from Waddington in 1961, moved to Scampton in 1969.
• RAF Scampton was the base for four operational squadrons at different times between 1961 and 1982
  • 27 Squadron 1961–1972, formed in 1961 to operate the B.2 until it disbanded in 1972. Reformed in 1973 to operate the B.2 (MRR) variant until 1982.[201]
  • 35 Squadron 1975–1982, moved from Akrotiri in 1975 and operated the B.2 until it disbanded in March 1982.
  • 83 Squadron 1960–1969, a former B.1/B.1A squadron at Waddington, reformed in 1960 to operate the B.2 until disbanded in 1969.[205]
  • 617 Squadron 1958–1981, formed in 1958 to operate the B.1, reformed to operate the B.2 in 1961 until disbanded in 1981.[207]
  • 230 OCU 1969–1981, moved from Finningley in 1969 until disbanded in 1981.
• RAF Waddington was the base for a number of operational squadrons at different times between 1957 and 1984, it was the first and last operational Vulcan base
  • 9 Squadron 1975–1982, moved in from Akrotiri in 1975 until it was disbanded 1982.[199]
  • 44 Squadron 1960–1982, formed in 1960 to operate the B.1/B.1A, it converted to the B.2 in 1966 and disbanded in 1982.[203]
  • 50 Squadron 1961–1984, formed in 1961 to operate the B.1/B.1A, it converted to the B.2 in 1966, from 1982 it also flew the tanker version until disbanding in 1984.[204]
  • 83 Squadron 1957–1960, formed in 1957 to be the first operational squadron to operate the B.1 until 1960, it reformed at Scampton later in the year as a B.2 unit.[205]
  • 101 Squadron 1961–1982, moved from Finningley in 1961 with the B.1/B.1A, converted to B.2 in 1967 and disbanded in 1982.[206]
  • 230 OCU 1956–1961, formed in 1956 to train Vulcan crews it moved to Finningley in 1961. A final move to RAF Scampton was made in 1970.

In the event of transition to war, the V Bomber squadrons were to deploy four aircraft at short notice to each of 26 pre-prepared dispersal airfields around the United Kingdom. In the early 1960s the RAF ordered 20 Beagle Basset communication aircraft to move the crews to dispersal airfields; the importance of these aircraft was only brief, diminishing when the primary nuclear deterrent switched to the Royal Navy's Polaris Missile.[211]

Notes