The Vickers Vanguard is a short/medium-range turboprop airliner designed and produced by the British aircraft manufacturer Vickers-Armstrongs.
The Vanguard was developed during the mid-to-late 1950s in response to a specification issued by British European Airways (BEA) for a 100-seat airliner; Vickers decided to design such an airliner as a follow-up to the existing Viscount series, the principal difference from which being an expanded airframe that provided considerably more internal volume. Another key innovation was the Tyne engine, which was roughly twice as powerful as the Viscount's Rolls-Royce Dart engine, and allowed for increases in both cruising speed and altitude. Throughout the design process, the needs of two airlines, BEA and Trans-Canada Air Lines (TCA), heavily shaped the Vanguard's specifics.
The Vanguard was brought into revenue service on 17 December 1960, around the same time as the commercial availability of a new generation of jet-powered airliners; as a result, these competitors quickly overshadowed its performance and led to the type being largely ignored by the market. Only 44 aircraft were ever built, the type having been ordered by BEA and TCA. After only about ten years' service, TCA experimentally converted one of its Vanguards to a freighter configuration, calling it the Cargoliner. Considered to be a success, the majority of Vanguards were converted into freighters during the early 1970s, those from BEA becoming the Merchantman. As a freighter, the type remained in service for many years, the final example being retired in 1996.
Development
Background The origins of the Vanguard can be traced back to speculative discussions between Vickers and the airline British European Airways (BEA) conducted as early as 1953, the same year in which the commercially successful Vickers Viscount airliner first entered revenue service. Even at this early stage, the two firms had envisioned the introduction of a successor to the Viscount entering service around 1959. This envisioned successor airliner would possess economics 10 per cent greater than those of the Viscount, while also being considerably faster throughout all operational stages. Out of BEA's internal analysis of various options, which studied both turboprop and pure jet propulsion arrangements, it became clear that a larger aircraft that could accommodate bigger payloads was highly desirable.Andrews 1969, p. 451.
On 19 April 1953, BEA's chief executive, Peter Masefield, outlined the company's requirements in a letter to Vickers; these criteria included a cruise speed of , a standard range of , with in reserve fuel, the ability to accommodate up to 100 passengers, and an explicit preference for a high-wing configuration. Coincidentally, another airline, Trans-Canada Air Lines (TCA), also made contact with the manufacturer with its own list of requirements, calling for a Viscount-like airliner capable of servicing its transcontinental routes while carrying up to 60 passengers. Recognising the potential to fulfil both airlines' requirements in a single airliner, Vickers' design team commenced work on producing such an aircraft.
Vicker's initial proposal, known as the Type 870 or alternatively as the Viscount Major, was incapable of meeting BEA's criteria, and was quickly dismissed. On 14 May 1951, Vickers met with Rolls-Royce representatives to discuss potential engines for their envisioned airliner; the meeting led to the decision to adopt the in-development Rolls-Royce Tyne powerplant for its revised proposal. While considerations towards adopting a turbojets engine were made, a study performed in November 1953 found that such an engine would produce inferior performance over shorter routes to a turboprop counterpart.Andrews 1969, pp. 451-452. It was around this time that Vickers' design team also discarded notions of adopting a swept wing, largely due to its providing little benefit at the envisioned airliner's cruise speed, as well as its inferior performance during the approach stage of flight.Andrews 1969, p. 452.
Redesign Despite BEA's initial preference for a high-mounted wing, the company opted for a low-mounted wing following the adoption of a double-bubble fuselage. This type of fuselage was necessary because of the large proportion of freight which BEA needed to carry. It was considered by Vickers to be impractical if carried at the same level as the passengers due to the excessive length that would be required, but carrying the freight in a lengthy hold beneath the main cabin was a practical arrangement. Furthermore, TCA wanted a low-mounted wing, which would make the aircraft easier to refuel, de-ice and service, as well as giving a statistically significant improvement in survival in the event of a water landing.Andrews 1969, p. 453.
By 13 April 1955, the range of design studies had been shortlisted down to five, these remaining concepts were jointly evaluated by BEA and Vickers. Of these submissions, it was recognised that the combination of the low-mounted wing and the double-bubble fuselage represented the optimum configuration, having offered the best capacity and versatility amongst other attributes. This conceptual aircraft, referred to as the Type 870 Scheme 16a, could accommodate 88 passengers, a cruising speed of at , and payload of . While BEA were interested in relatively short, sub-1000 mile, routes, its fuel tanks were progressively enlarged over several revisions to give a range of so that the airliner would be acceptable to TCA as well.Andrews 1969, p. 454.
The Type 900 was a further revision of the design, featuring an expanded payload capacity of and carry up to 93 passengers. Following some relatively minor revisions, which largely bolstered the gross weight upwards, that were made to better suit the design to the needs of global customers, the definitive Type 950 proposal emerged. On 20 July 1960, BEA placed an initial order for 20 Type 950s, the type becoming subsequently known as the Vanguard; the airline publicly announced the order and its intended plan for the new airliner to succeed the Viscount in its fleet.Andrews 1969, p. 455.
At the time, TCA was, while intensely interested in the airliner, not yet willing to commit itself, partially due to the basic model not entirely fulfilling its requirements, such as the level of capacity for air mail. Vickers recognised that a high-density seating configuration, accommodating up to 139 passengers to be carried, would likely be attractive to more operators, and designed the Type 952 model for this market. Following a particularly vigorous evaluation, during early January 1957, TCA announced that it had placed an order for 20 Type 952s. With a follow-on order for three more aircraft, it would be, measured in dollar worth, the largest single export deal in postwar Britain's history at that time.
Into production The launch of the programme commenced immediately following BEA's initial order for the type. Due to the substantial growth of the airliner during the concept phase, engine supplier Rolls-Royce set about scaling up the Tyne engine from its initial output of to at least . As the Vanguard's production line was coming online at Vickers' Weybridge facility, BEA recognised that, due to the typically short length of its routes, a higher density economy seating configuration could be adopted without impacting performance. Accordingly, on 23 July 1957, Vickers announced a new model, the Type 953, which could handle payloads of up to , which greatly improved the operating costs for BEA's preferred model; the airline quickly converted its order to six Type 951s and 14 Type 953s.Andrews 1969, p. 456.
On 20 January 1959, the first Type 950 prototype G-AOYW conducted its maiden flight.Wright Air International April 1997, p. 242.Andrews 1969, pp. 456-457. The flight, a transfer to Wisley three miles away, had been planned for December but the engines were returned to Rolls-Royce for minor work. Proper flight testing was then carried out from Wisley."Vanguard Maiden Flight." Flight, 30 January 1959, p. 150. While development proceeded relatively smoothly, apart from over 2,000 flights being required to resolve unacceptable stalling characteristics, the last weeks of trials with BEA in early 1960 uncovered some engine-related difficulties, necessitating a brief delay while the compressor rotor was modified.Andrews 1969, pp. 458-459. With the issue resolved, the Vanguard entered revenue service with TCA on 1 February 1961, and with BEA one month later.Andrews 1969, p. 459.
However, by the time of the Vanguard's entry to service, the attitudes of the travelling public had shifted in favour of the new bypass jet engines which did not use propellers.Andrews 1969, pp. 459-460. Passengers typically preferred the additional speed, even at the disadvantage of greater operating costs and thus higher ticket prices, that came with jet-powered airliners. As such, the turboprop-powered Vanguard did not sell well, although those examples that were introduced typically performed well in numerous capacities, and often had lengthy service lives.Andrews 1969, p. 460.
Design The Vickers Vanguard was a turboprop-powered airliner designed for short- and medium-range services. The principal difference between the Vanguard and the preceding Viscount was in the construction of the fuselage; the Vanguard lower fuselage was similar to that of the Viscount but the top section had a larger-diameter giving a double bubble cross-section (somewhat similar to the Boeing Stratocruiser). The primary result of the larger upper portion was a more spacious interior, along with an increase in cargo capacity below the floor of the main cabin.Swanborough 1962, p. 99. A low-mounted straight wing was also adopted for the type, despite considerations towards shoulder-mounted and swept-wing alternatives.Andrews 1969, pp. 452-453. Aviation author C. F. Andrews observed the design to be orthodox in practically every respect.Andrews 1969, pp. 457-458.
The Vanguard's larger and heavier fuselage presented an obvious need to be combined with a more powerful engine, which led to the adoption of the newly developed Rolls-Royce Tyne engine. This powerplant was capable of generating a nominal , in comparison to the Viscount's Rolls-Royce Dart of about . The Tyne engine enabled the Vanguard to be operated at a substantially greater service ceiling and cruising speed. The Vanguard was one of the fastest turboprop airliners to ever be built, including much later designs such as the Saab 2000 and de Havilland Canada Dash 8. A pilot report describes maintaining altitude with three engines at idle power and propellers feathered and the port outer engine at maximum cruise power.Aviation Week, 14 September 1959, pp. 57, 59.
The flight deck of the Vanguard was particularly spacious for the era.Andrews 1969, p. 458. The flying controls were designed with manual operation in mind and were aerodynamically balanced. In spite of this arrangement, according to Andrews, the onboard electrical systems were a major advance over the previous generation of airliners; amongst other capabilities, the engines could be started without the aid of a ground support cart. The Vanguard possessed relatively docile stall characteristics, in part due to the dihedral positioning of its horizontal stabiliser, which kept it clear of the jet efflux from the engines and aided longitudinal stability.Andrews 1969, p. 457. However, acceptable stalling behaviour only came after an extensive programme of over 2,000 stalls to correct initial very violent tendencies which included rolling inverted.Trubshaw, Brian, with Edmondson, Sally, Test Pilot, , p. 48
Operational history