The Avro Vulcan, sometimes referred to as the Hawker Siddeley Vulcan, was a jet-powered delta wing strategic bomber, operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A V Roe & Co (Avro) designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced, the Vulcan was considered the riskiest option. Several scale aircraft, designated Avro 707, were produced to test and refine the delta wing design principles.
The Vulcan B.1 was first delivered to the RAF in 1956; deliveries of the improved Vulcan B.2 started in 1960. The B.2 featured more powerful engines, a larger wing, an improved electrical system and electronic countermeasures (ECM); many were modified to accept the Blue Steel missile. As a part of the V-force, the Vulcan was the backbone of the United Kingdom’s airborne nuclear deterrent during much of the Cold War. Although the Vulcan was typically armed with nuclear weapons, it was capable of conventional bombing missions, a capability which was used in Operation Black Buck during the Falklands War, a conflict between Britain and Argentina in 1982.
The Vulcan lacked defensive weaponry, initially relying upon high-speed high-altitude flight to evade interception. Electronic countermeasures were employed by the B.1 (designated B.1A) and B.2 from circa 1960. A change to low-level tactics was made in the mid-1960s. In the mid 1970s, nine Vulcans were adapted for maritime radar reconnaissance operations, redesignated as B.2 (MRR). In the final years of service, six Vulcans were converted to the K.2 tanker configuration for aerial refuelling. Since retirement by the RAF one example, B.2 XH558, named "The Spirit of Great Britain" has been restored for use in display flights and air shows.
The Vulcan normally operated with a crew of five: two pilots, two navigators and an Air Electronics Operator (AEO), with the AEO responsible for all electrical equipment in a role similar to that of flight engineer on earlier propeller aircraft. Only the pilot and co-pilot were provided with ejection seats; the fact that the rear crew were not provided ejection seats led to considerable criticism. There were several instances of the pilot and co-pilot ejecting in an emergency and the rear crew being killed because there was not enough time for them to bail out.
Despite its large size, it had a relatively small radar cross-section (RCS) as it had a fortuitously stealthy shape apart from the tail fin; at certain angles, it would vanish from the radar altogether. The Vulcan used entirely powered control surfaces; this allowed a joystick to be used instead of a larger yoke. This system provided a synthetic controls "feel"; flying conditions were fed back to pilot flying as a proportional resistance to his control inputs based upon the aircraft's dynamic flight configuration.
Engine
The Rolls-Royce Olympus, originally known as the 'Bristol BE.10 Olympus', 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 centre of the fuselage. Engine design began in 1947, intended to power the Bristol Aeroplane Company's own rival design to the Vulcan. The engine would later be developed into a reheated powerplant for the cancelled supersonic BAC TSR-2 strike bomber and the supersonic passenger transport Concorde.
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. VX770 later became a flying test bed for the Rolls-Royce Conway. 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 of 11,000 lbf (49 kN) thrust. 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.
Early B.1s were engined with the Olympus 101. Later aircraft were delivered with Olympus 102s. All Olympus 102s became the Olympus 104 of 13,000 lbf (58 kN) thrust on overhaul and ultimately 13,500 lbf (60 kN) thrust on uprating. The first B.2 flew with the second-generation Olympus 200 of 16,000 lbf (71 kN) thrust, design of which began in 1952. Subsequent B.2s were engined with either the uprated Olympus 201 of 17,000 lbf (76 kN) thrust or the Olympus 301 of 20,000 lbf (89 kN) thrust. The Olympus 201 was designated 202 on being fitted with a rapid air starter.
Electrical and hydraulic systems
The main electrical system on the B.1/B.1A was 112V DC supplied by four 22.5kW engine-driven generators. Backup power was provided by four 24V 40Ah batteries connected in series providing 96V. Secondary electrical systems were 28V DC, single-phase 115V AC at 1600Hz, and three-phase 115V AC at 400Hz, driven by transformers and inverters from the main system. The 28V DC system was backed up by a single 24V battery.
For greater efficiency and higher reliability, the main system on the B.2 was changed to three-phase 200V AC at 400Hz supplied by four 40kVA engine-driven constant speed alternators. Standby supplies in the event of a main AC failure were provided by a Ram Air Turbine (RAT) driving a 17kVA alternator that could operate at high altitude down to 20,000 ft (6,100 m), and an Airborne Auxiliary Power Plant (AAPP), a Rover 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 similar to the B.1.
The change to an AC system was a significant improvement. The Vulcan's powered flying controls were hydraulically actuated but each Powered Flying Control Unit (PFCU) had a hydraulic pump which was driven by an electrical motor. 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.
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.
Avionics
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). The Vulcan B.1A also featured an UHF transmitter/receiver (ARC-52). The initial B.2 radio fit was similar to the B.1A though it was ultimately fitted with the ARC-52, a V/UHF transmitter/receiver (PTR-175), and a SSB HF transmitter/receiver (Collins 618T).
The Navigation and Bombing System (NBS) comprised an H2S Mk9 radar and a Navigation Bombing Computer (NBC) Mk2. Other B.1 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 ILS. TACAN replaced GEE in the B.1A and B.2 and Decca Doppler 72 replaced Green Satin in the B.2. A running fix of the aircraft's position was maintained by a Ground Position Indicator (GPI). Vulcan B.2s were eventually fitted with the gyroscopic Heading Reference System 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. The B.2 (MRR) was additionally fitted with the LORAN C navigation system.
The flight instruments in the B.1 were traditional and included G4B compasses; Mk.4 artificial horizons; and zero reader flight display instruments. The B.1 had a Smiths Mk10 autopilot. 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. From 1966, B.2s were fitted with the ARI 5959 Terrain-following radar (TFR), built by General Dynamics, its commands being fed into the director-horizons.
The original ECM fit as fitted to the B.1A and B.2 was: one Green Palm voice communications' jammer; two Blue Diver metric jammers; three Red Shrimp S-band jammers; four Blue Saga Passive Warning Receivers (PWRs); one Red Steer tail-warning radar; and window (chaff) dispensers. 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. Later equipment on the B.2 included: an L-band jammer (replacing a Red Shrimp); the ARI 18146 X-band jammer; 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.
Colour schemes
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 'type D pale' roundels.
With the adoption of low-level attack profiles in the mid-1960s, B.1As and B.2s were given a glossy medium sea grey/olive 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). In the mid-1970s: Vulcan B.2s received a medium sea grey/olive green matte camouflage with light 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 olive green because, during Red Flag exercises in the USA, 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.
