Profile – Avro Vulcan

As one noted aviation writer put it in 1980: “not least of the claims to fame of the Vulcan is that, at a time when almost all British aircraft were so fatigue-prone it is remarkable they ever got through their flight test programme, this spacious multi-path structure has not only stood up to 20 years of tough combat duty already-and feels fine-but has lived most of its life in the thick, gusty air of low levels, far more severe than the serene stratosphere for which it was designed”.

This is but one aspect in the story of a remarkable aeroplane which began life as a 1945 British Air Staff Operational Requirement (OR 229) for a state-of-the-art Avro Lincoln replacement and in effect ended 37 years later with a handful of bombing raids over the Falklands Islands, the only time the Vulcan was ever used for its intended purpose in a conflict.

In between these two events came something of a triumph of engineering achievement, of development and of the practical application of what was a genuinely radical basic design.

Operational Requirement 229 – in refined form Air Staff Requirement B. 35/36 issued in January 1947- was a document which demanded a bomber with capabilities which would stretch British industry’s capabilities to the limit. It called for a four-jet bomber capable of carrying a 10,000lb nuclear bomb or a wide range of conventional weapons a distance of 1500 nautical miles (and return) at a speed of Mach 0. 873/500 KTAS and at altitudes ranging from 35,000ft at the beginning of the mission to 50,000ft 2. 5 hours later when the fuel load had lightened.

The availability of captured German information on advanced wing designs and British industry’s own research indicated that these requirements were not impossible in themselves, but the specification’s requirement that the bomber’s maximum takeoff weight be limited to 100,000lb did make them so. The limit allow operations from “normal bomber airfields” – was soon raised to 115,000lb which helped little: by comparison the Boeing B-29’s maximum weight was normally 135,000lb.

Other requirements written into the specification included all-weather capability, high manoeuvrability, provision for radio warning and counter-measures equipment and provision for defensive tail armament should the need for it arise. A crew of five would be carried (two pilots, two navigators/bomb aimers who would use the H2S radar in turn and a communications/ electronic countermeasures operator) in a pressurised capsule which could be ejected complete if bailing out became necessary. This latter idea was never fitted, and as described later, the issue of crew survivability was one of Vulcan’s few major points of design criticism.

The men behind Avro’s earliest attempts to come up with a design which met the demanding specification were Roy Chadwick, the company’s newly-promoted Technical Director and the man responsible for the Lancaster and Lincoln, and Stuart Davies, who succeeded Chadwick as Chief Designer.

Their and their staff’s investigations into the apparently conflicting requirements – the weight limit providing the main bugbear-took them through various configurations ranging from an initial jet-powered Lincoln with a slightly swept wing (which failed to provide the necessary performance) to assorted new designs with conventional tails and wings swept at around 45 degrees. Although most of the performance objectives were met, the weight one certainly wasn’t, and the first “firm” proposal for such an aircraft (with the engines buried in the wings Cometstyle) would have weighed in at a staggering 193,000lb maximum!

At this stage none of the other companies engaged in designing a bomber to specification B. 35/46 were able to meet the weight requirement either, at least not without reducing fuel capacity and/or bomb load to a degree which meant the payload/ range demands would not be met by a substantial margin. The trouble was that a swept wing produced less lift than a straight one, so therefore a larger wing was required to satisfy the aircraft’s appetite for lift. A larger swept wing weighed more, a straight wing would not provide the necessary speed and range. . . . it was an apparently unsolvable dilemma.

Chadwick’s team therefore began looking at more radical alternatives before 1947 was three months old. A possibility was to remove the horizontal tail surfaces altogether (thus saving weight) and redesign the whole aircraft with a minimal fuselage and large wing. Such tailless aircraft were already in existence, and Avro drew considerable input from its associated company Armstrong-Whitworth who would soon be flying their small, tailless jet, the AW. 52 research aircraft and had had a glider version, the AW. 52G, in the air since 1945. The AW. 52 had a large sweptback wing, a fin and rudder at each wingtip (in fact the rearmost point of the aircraft) and a small nose/cockpit section for the single crew member.

Avro’s earlier sketches along these lines looked very much like a larger version of the AW. 52, but still the weight was too high, a figure of 137,500Ib being the initial estimate. Somehow the span had to be reduced as a weight-saving measure, and thus the incorporation of an almost perfect triangle “delta” wing began. As the design’s span was reduced, its chord increased (as did its thickness) and the delta wing took shape.

The aerodynamic properties of the delta seemed sound, a fact confirmed by captured German documents which revealed Dr Alexander Lippisch’s experiments with tailless aircraft between 1931 and 1945. Lippisch had flown tailless gliders with success up until 1937 and during World War II had been responsible for the Messerschmitt Me163 Komet rocket-powered interceptor.

Lippisch made the natural transition to delta wing designs late in the war and had overseered considerable wind tunnel research on the project, much of which was documented and available to Chadwick and his team.

Thus evolved the first Avro Type 698 as presented to the Ministry of Supply in May 1947, and it resembled what would ultimately become the Vulcan only in general layout. To the eyes of those within the Ministry, Chadwick’s proposed aeroplane must have been startling. A pure delta of enormous root chord (almost 70 feet) and great thickness with vertical tail surfaces at the tips, huge circular engine intakes at the root to house the superimposed-in-pairs engines, the proposed Bristol BE. 10, which later developed into the Olympus.

The 698 had a recognisable nose section to house the five crew members (earlier designs just about dispensing with that altogether) and a conventional tricycle undercarriage, although an outrigger design was at first considered.

The method of carrying the bomb load and fuel evolved along with the design of the rest of the aeroplane. As it was submitted to the Ministry in May 1947 the 10,00Olb atomic bomb was carried in a bay in the port wing immediately outboard of the engines and the fuel was carried in a similarly-positioned bay in the starboard wing. Further evolution resulted in the placement of both fuel and bombs in each wing, then placing the bombs in panniers under the wings and finally, the bombs were moved to a fuselage bay when it was realised a slightly thinner wing would be required to achieve the bomber’s design speeds. Additional fuel was also carried in a fuselage tank immediately behind the crew compartment.

Roy Chadwick’s personal reputation and influence played a great part in the Ministry’s acceptance of the Avro 698 design. But tragedy took a hand in August 1947 when Chadwick was unnecessarily killed in the crash of the prototype Avro Tudor 2 airliner. Someone had connected the aircraft’s aileron controls the wrong way round. . . .

There was some fear at the time that Chadwick’s death (and the resultant loss of his influence) would spell the end of the project for Avro, but in November 1947 it was accepted, along with Handley-Page’s crescent-winged and very fast subsonic HP. 80 design, later to become the famous Victor.

Here was developing a typically British aerospace situation.

Both the Avro 698 and the HP. 80 would eventually find themselves in parallel production, each one suffering by the necessarily relatively low production tally and therefore high unit costs that created. On top of that there was the research and development cost of two very advanced and expensive aircraft.

The official attitude was that each aircraft would act as insurance against the other’s failure. As it turned out, both were successful and both enjoyed long service lives with the victor still serving today as a tanker.

But not even that was sufficient to assure the powers to that be that the Royal Air Force would have an effective strategic bomber force courtesy Avro’s and Handley-Page’s advanced designs. As further insurance, the much less technologically advanced Vickers Type 660 was ordered into production as the Valiant, the type entering service in 1954, several years ahead of the other two aircraft. A special reduced specification was written around the Valiant (B. 9/48) as the aircraft did not meet the original B. 35/46 targets. So for a decade until the Valiant was phased out of service in 1964 due to fatigue problems, Britain had no fewer than three types in its so-called “V-Bomber” force, all designed to perform basically the same role!

Meanwhile, the Avro 698 design had progressed to a form close to its final one by the end of 1948, with orders for two prototypes having been placed at the beginning of the same year. Now the four engines were mounted in more conventional side-by-side pairs in the wing roots, the vertical fins at the wing tips had been replaced by a single conventional dorsal fin and the flight control system’s design was close to being finalised.

This had also progressed through various stages. Early thoughts centred around pivoting wing tips for lateral control with the mechanism mounted in the now slightly inboard tip fins, but when they disappeared so did the movable wing tips, these being replaced by inboard elevators and outboard ailerons on the trailing edges of the delta wing. Interestingly, there was still some considerable doubt about the 698’s longitudinal stability, and the new central fin was designed to carry a conventional horizontal tailplane should it be required. At the same time the circular engine intakes became the familiar rectangular shape.

Minimum Concept

But despite the HP. 80 and the Valiant, the Ministry’s need for insurance was still not satisfied. “Proof of concept” prototypes were also called for, small single-jet aircraft designed to prove the effectiveness of Handley-Page’s crescent wing and Avro’s delta. Thus were born the HP. 88 and the Avro 707.

The first of five 707s flew in September 1948, this being intended for low-speed research and powered by Rolls-Royce Derwent engine with its air intake mounted on the top of the fuselage. In order to simplify construction, this short-lived first 707 “mini-Vulcan” (it crashed within a month of flying) used a Gloster Meteor canopy and nose gear and Avro Athena (a Merlin powered trainer) main undercarriage.

The following Avro 707s were too late to serve any useful role in Vulcan development, the next example not flying for the first time until September 1950 by which time construction of the first bomber was well under way. The Avro 707B was also intended for low-speed research and was fitted with a longer nosewheel strut (something which did actually help the Vulcan’s development), a new nose design and other detailed refinements, while the two 707As (first flown June 1951) were for high-speed research and had wing root intakes, an ejection seat and an extended dorsal fin fairing.

The final 707 built was the ‘C’ model in 1953, a side-by-side two-seat development of the 707A intended for the training of future delta wing pilots.

The 707s proved what Avro’s designers had known all along – that the delta wing concept was viable and even something of a breakthrough as far as flying characteristics and manoeuvrability went – and proved themselves admirably but contributed little to the Vulcan programme itself. There were one or two exceptions, however. One was the lengthened nosewheel mentioned above, another was the convincing of all concerned that a yaw damper should be fitted to the 698. The 707’s bad timing meant that its potentially biggest contribution to the 698 programme was too late to prevent a costly re-think. It was discovered that the wing of the 707A increasingly “buzzed” as height and speed increased, and this could be cured by putting a “kink” in the delta’s leading edge. This was ultimately done to the Vulcan – as will soon be described – but meanwhile the Vulcan was already in production and a healthy quantity of expensive straight leading edges had to be scrapped and replaced with kinked units.

Into the Air and into Production

The prototype Vulcan (VX770) made its first flight from Avro’s Woodfield aerodrome on August 30, 1952, two months after a production contract for 25 had been placed. The pilot was the flamboyant Wing Commander R. J. ‘Roly’ Falk. This aircraft was hardly representative of production aircraft, being powered by four 6500Ib thrust Rolls-Royce Avans as the chosen engine, Bristol’s Olympus, had not yet been cleared for flight. The prototype also lacked many of the other features of the production aircraft including any wing fuel tanks, military equipment, an operative pressurisation system and a copilot’s seat.

Nevertheless, it was an impressive aeroplane, with a length and wingspan of just under 100 feet and a massive wing area of 3554sq ft (330m2). Its construction was conventional despite its unusual appearance, most of the aeroplane being built from standard high strength light alloys, although in order to save weight some magnesium alloy was included in the control surfaces and bomb doors.

The Vulcan derived its massive strength from the sound structural principals used on the Lancaster – a two-spar wing of orthodox boom and web construction built as a single piece from port to starboard with cutouts where appropriate for the engines and so on.

Nine main sub-assemblies had to be brought together to complete a Vulcan, the nose section containing the radar scanner; the forward fuselage with the canopy and crew compartment; the intakes and centre fuselage (with fuselage fuel tank), the enormous centre section which was 35 feet long by 28 feet wide and comprised the main part of the fuselage, the engine and bomb bays plus the intakes and fuselage/wing junctions; the trailing edge/rear fuselage section; two sets of wing leading edges and a similar number of outer wings. Added to that were the fin and rudder assembly plus the wing trailing edge control surfaces.

The Royal Air Force paid about £750,000 for each of its early production Vulcans and for its money received 167,063 separate parts (excluding engines), 410,300 nuts, bolts, washers and rivets, nearly two miles of tubing and 14 miles of electrical wiring.

The crew compartment was an area that was subject to discussion throughout the Vulcan’s career. The idea of an escape capsule for the five crew members was abandoned due to enormous difficulties in being able to design a system which would work, so a revised layout was introduced. This had the two pilots on ejector seats under a small jettisonable canopy incorporating a minimum of window transparencies. The three radio/radar/navigation officers were placed behind and below the pilots, facing rearward. For them there was no such thing as the luxury of ejector seats, merely an escape hatch in the floor below them. Many of these ‘rear-seaters’ were lost unnecessarily due to the difficulties involved in escaping from a doomed Vulcan.

Other salient features of the Vulcan as it finally emerged were its enormous glass fibre radome on the lower half of the nose covering the radar, its double bogey Dowty main undercarriage and twin nosewheels, its anti-skid Maxaret disc brakes, very effective air brakes above and below each wing (profile drag increased by 250% when these were fully deployed), a yaw and pitch damper/Mach trimmer system, a fuel trim system which kept the Vulcan’s centre of gravity constant during a flight as its approximately 74,000Ib fuel capacity was gradually burnt off and its hydraulically-powered controls with multiple redundancies and no manual reversion.

The final pre-production major modification was the designing of a drooped and kinked wing leading in response to a buffet problem discovered during wind tunnel testing and on the Avro 707A proof-of-concept aircraft after the prototype Vulcan was already flying. The modified wing was dubbed the ‘Phase 2’ wing.

The new leading edge solved the problem and consisted of two sections starting from just short of half-span on each wing. The inboard portion had reduced sweep and therefore progressively greater chord while the outer section (from 78% span) had greater sweep than before which reduced the chord value to nearly its original value at the tip. All but the two prototypes and the first handful of 45 production Vulcan 8. 1s were fitted with the Phase 2 wing before first flight.

Meanwhile the Avon-powered prototype had been thrilling the crowds at the 1952 SBAC show at Farnborough within days of its maiden flight and under the expert guidance of ‘Roly’ Falk. This aircraft was in 1953 subject to a substantial series of modifications including the installation of 7500Ib thrust Armstrong Siddeley Sapphire engines (as fitted to the Victor), wing fuel cells and an operational pressurisation system.

The second prototype (VX777) was Olympus-powered from the day of its first flight in September 1953 and was much more representative of the production aircraft, although it was initially fitted with the ‘straight’ delta wing, as were early production aircraft. The first of these (XA889) flew in February 1955, although it was to be another two years before the first true service aircraft were handed over to No230 OCU and not until July 1957 that No83 Squadron became the first operational unit to take the Vulcan.

The seemingly lengthy delay between the maiden flight of the first production aircraft and the first squadron delivery was as a result of the extensive testing burden (nearly 18 months) on the shoulders of the sole Olympus-powered (second) prototype and the fact that this aircraft was out of action for some time in 1954 following a heavy landing at Farnborough. Through its life, VX777 was also fitted with progressively more powerful Olympus engines and later was converted to the prototype Vulcan 8. 2. The rejigging of the Phase 2 wing inevitably added to the ‘in service’ date as well.

Production Vulcan 8. 1s were initially powered by 11,000lb thrust Olympus 101 engines and were subsequently fitted with 12,000 and 13,500lb thrust Olympus 102 and 104 powerplants. The designation Vulcan 8. 1A was applied to 29 aircraft as they were progressively fitted with an extensive electronic countermeasures suite mounted in an extended tail fairing. Some 8. 1s were also fitted with a flight refuelling probe at the nose. Happily, the ‘maximum takeoff weight limit of the original specification had been long discarded, and the 8. 1’s maximum was somewhere in the region of 190,000lb in the later aircraft.

Bigger and Better

The Vulcan 8. 2 came about with the need to carry the Avro Blue Steel rocket-powered atomic “stand-off” missile, and this version featured considerable redesign over the first production model.

“Higher and further” were basic design requirements and to achieve this the 8. 2 was fitted with 17,000lb thrust Olympus 201 engines, the substantially redesigned, increased-span ‘Phase 2C’ wing, enlarged inlet ducts and jet pipes, a further enlarged tail fairing to house the ever-increasing range of ECM equipment fitted, a complete restressing of the structure and landing gear to cope with ultimate gross weights of 225,000lb (with accompanying benefits in long-term fatigue life), a new electrical system of considerably greater capacity and a completely redesigned flight control system with inner and outer elevons each split into two parts with separate and independent power units on each wing replacing the previously fitted ailerons and elevators.

This and the other changes introduced with the Vulcan B. 2 necessitated a major testing programme and involved some 13 of the early production aircraft plus the second prototype which was converted to take the B. 2’s new wing and first flew in this guise in August 1957.

It was decided to built the final 15 Vulcan B. 1s to the new and much more capable standard, such was the eagerness of the RAF to have this aircraft, and the first true B. 2 (XH553) flew in August 1958, six months before the final B. 1A left the factory.

This and the following six aircraft were used for development trials and the first to be delivered to the RAF was handed over to 230OCU in July 1960 with squadron service following soon after.

Eighty-nine Vulcan B. 2s were built, the last one coming off the line in 1964. A final sub-variant was the Vulcan SR. 2, a strategic reconnaissance version converted from normal B. 2s which first appeared in 1973.

The Vulcan’s originally intended role of a strategic bomber with nuclear deterrent capability (although 21,000lb of conventional bombs could be carried) was relatively short-lived. The B. 2 version was developed specifically to carry the Blue Steel missile, and this it did only between 1963 and 1966, the famous 617 “Dam Busters” squadron being the first to become operational with the weapon.

But a change of government policy almost immediately after this changed the role of the Vulcan force completely. It was decided that the responsibility of providing a nuclear deterrent would transfer to the Royal Navy through its Polaris-equipped submarines, and that the Vulcans would be used for low level penetration missions, a role they performed until their retirement in the early 1980s.

It was in this role that the great structural strength of the Vulcan B. 2 came into play, particularly as a result of the modifications incorporated into the B. 2. The Vulcan slipped into its new role extremely well and with the continuing updating of the ECM avionics suite and with increased crew experience became masters of the trade.

Externally, the Vulcan looked different in its new role. Gone was the all-white anti-radiation finish, in its place came the grey/ green camouflage scheme more suited to low-level operations. At about the same time of this change, the B. 2s were fitted with 20,000lb thrust Olympus 301 engines and terrain-following radar.

A Last Hurrah

By April 1982 only four of the eight Vulcan squadrons which had survived to the late 1970s were still in existence, and they were due to be disbanded by the middle of the year. But fate and the Argentinean invasion of the Falklands Islands on April 2 gave the Vulcan a slight life extension and a brief chance to indulge in live missions.

Several Vulcans were prepared to undertake missions over the Falklands, and two of them-XM597 and XM607 took off from Ascension Island on April 30 to bomb the airfield at Port Stanley in Operation Black Buck 1. XM597 had to turn back early in the 16 hour, 7772 mile (12,507 km) two-way mission due to its cabin failing to pressurise. This left XM607 with Flt Lt Martin Withers and his 101 Squadron crew to carry the can alone, and in company with the ten (repeat 10!) Victor tankers required to complete the difficult mission, carried on to Port Stanley airfield whereupon a stick of 21 1000-pounders was dropped at an angle of 35 degrees across the runway from 10,000 feet and at night.

Despite the elderly bomb-aiming equipment, a remarkable and somewhat unexpected degree of accuracy was achieved when the first bomb hit the runway fair in its centre, while others hit a hangar, a store dump and the only road from the airfield to the town, the latter causing the Argentineans a great deal of inconvenience.

The next raid, Black Buck 2, was mounted on May 3, and this time Sqdn Ldr John Reeve flew XM607, dropped his bombs from 16,000 feet and narrowly missed the runway. The similar Black Buck 3 was planned for May 16 but was cancelled due to adverse headwinds, while Black Bucks 4, 5 and 6 were anti-radar missions using US-built Shrike anti-radar missiles. This armament installation was hurriedly “cobbled up” by the RAF and these raids achieved little success. The first of them was in fact aborted when the Vulcan concerned lost its flight refuelling probe after takeoff.

The Vulcan finally retired from RAF service on 31 March 1984, the final unit operating the type being No 50 Squadron which had Vulcans hastily converted to tankers by Flight Refuelling Ltd in mid-1982 as a result of the Falklands experiences. These aircraft were designated Vulcan B. 2(K). Of course, no description of a British aircraft would be complete without an “if only” section. In the case of the Vulcan the “if only” refers to would might have been known as the Vulcan B. 3. As proposed by Avro in 1960, this Vulcan would have had double the capability of existing Vulcans, used 22,500lb thrust Olympus 23 engines, had a completely new near-delta wing of increased span installed, provision for external stores (including missiles) and a restressed structure allowing an increase in MTOW to something in the region of 350,000lb. Range with full load would have been around 5000 nautical miles. Officialdom was not interested.

With or without the B. 3, the Vulcan was a truly remarkable aircraft which remained a formidable weapon for far longer than its creators could possibly have envisaged. Its sinister appearance and unusual features only added to its aura and its versatility reinforced its user’s strong opinion of it in service.