Vickers Viscount

The Vickers Viscount is a retired British medium-range turboprop airliner first flown in 1948 by Vickers-Armstrongs. A design requirement from the Brabazon Committee, it entered service in 1953 and was the first turboprop-powered airliner.

The Viscount was well received by the public for its cabin conditions, which included pressurisation, reductions in vibration and noise, and panoramic windows. It became one of the most successful and profitable of the first postwar transport aircraft; 445 Viscounts were built for a range of international customers, including in North America.

Development

Origins

thumb|Five-abreast cabin

thumb|Front cabin

thumb|upright|Cockpit

The Viscount was a response to the 1943 Brabazon Committee's proposed Type II design for a postwar, small, medium-range, pressurised aircraft to fly less-travelled routes, carrying 24 passengers up to 1,750 mi (2,816 km) at 200 mph (320 km/h). During discussions between the committee and Vickers' chief designer, Rex Pierson, Vickers advocated turboprop power. The committee was not convinced and split the specification into two types, the Type IIA using piston power, which led to the Airspeed Ambassador, and the turboprop-powered Type IIB, which Vickers was selected to develop in April 1945. British European Airways (BEA) was involved in the design and asked that the aircraft carry 32 passengers, instead, but remained otherwise similar.

The first design in June 1945 was based on the Viking with four turboprop engines and 24 seats and designated the VC-2 or Type 453. Later, a double-bubble fuselage was proposed to give extra underfloor cargo space. The decision for pressurisation resulted in the double-bubble and elliptical fuselage designs being abandoned.|group=N other engines were considered, including the Armstrong Siddeley Mamba, which the government specified for the two prototypes. The choice of the Mamba engine increased the weight, but Vickers made sure the engine nacelle would fit either the Mamba or Dart. While the Dart progressed better in development, the government asked in August 1947 for the second prototype to be Dart-powered. Work took place on replacing the Darts with the Mamba, but this was dropped by the time the prototypes were reaching completion. After Pierson's death in 1948, George Edwards (later Sir George Edwards) took over as chief designer and assumed all technical control over the Viscount project.

Prototypes

The prototype Type 630, registered G-AHRF, made its maiden flight from the grass airfield at Wisley on 16 July 1948, piloted by Joseph "Mutt" Summers, Vickers' chief test pilot. The design was considered too small and slow at 275 mph (443 km/h), making the per-passenger operating costs too high for regular service, and BEA had placed an order for 20 piston-engined Airspeed Ambassadors in 1947. Retrospectively commenting on Britain's aviation industry, Duncan Burn stated: "Had BEA committed itself to full support of the Viscount... it was quite likely that the smaller version would have gone into production... It was in a sense BEA's lack of enthusiasm for the [Type] 630 which made possible the [Viscount's] success."

Early flight trials, however, showed the qualities of a turboprop, resulting in a February 1949 order from the Ministry of Supply for a prototype of a stretched version with more powerful engines, the Type 700. Meanwhile, the first prototype Type 630 was awarded a restricted Certificate of Airworthiness on 15 September 1949, followed by a full certificate on 27 July 1950, which allowed the aircraft to be placed into trial service with BEA on 29 July to familiarise the pilots and ground crew with the new aircraft. It flew scheduled flights between London and Paris, and London and Edinburgh until 23 August 1950. The 29 July 1950 flight between Northolt and Paris – Le Bourget Airport with 14 paying passengers was the first scheduled airline flight by any turbine-powered aircraft.

thumb|Type 663 Tay Viscount demonstrating at Farnborough in September 1950

The second prototype Viscount, the Type 663 testbed, had two Rolls-Royce Tay turbojet engines, and first flew in RAF markings as serial VX217 at Wisley on 15 March 1950. It was demonstrated at the Farnborough SBAC Show in September and was later used in the development of powered controls for the Valiant bomber.

The designers then went back to the drawing board and the aircraft emerged as the larger Type 700 with up to 48 passengers (53 in some configurations), and a cruising speed of 308 mph (496 km/h). The new prototype G-AMAV first flew from Brooklands on 28 August 1950, and served as a development aircraft for the type for several years. In late August 1950, BEA placed an order for 20 aircraft; further orders came in the following year from operators such as Air France, Aer Lingus, and Misrair. In 1953, the basic cost given for a Viscount was £235,000.

Performance and changes

thumb|upright|The Viscount's large oval windows, Air Zimbabwe 1981

One reporter, after travelling on an Air France Viscount, wrote in 1953: "Noise level was less than that of piston engines. It was a definite relief to be rid of the rough vibrations... The turboprop is an excellent shorthaul airplane and a definite crowd pleaser. The substitution of a lower constant-pitch noise and smoothness for the vibration, grunts, and groans of the piston engine gives the hesitant passenger a feeling of confidence." Viscount cabin windows were huge ellipses, 19 by 26 inches. Viscount operational costs were lower than many rival aircraft;

All production Viscounts were powered by the Rolls-Royce Dart turboprop; from its initial 800 hp, and then 1,000 hp and higher, Rolls-Royce extensively developed the Dart engine, due to its popularity and use on the Viscount and several later aircraft. One key model was the Dart 506 engine, with better fuel efficiency than earlier models, allowing airline Viscounts to fly longer routes, with more payload. With the availability of more powerful engines, Vickers continued to develop the Viscount's design. Later models could carry more passengers and had fewer load limitations.

Three basic versions of the Viscount were built. The first production version was the Type 700 powered by R.Da.3 Dart 505 and later R.Da.3 Dart 506s. A subvariant was the type 700Ds powered by R.D.a Dart 510s.

The second version was the Type 800, which was shorter in range and had a higher passenger capacity aircraft than the 700. The fuselage was lengthened and the rear pressure bulkhead was moved aft , allowing more passengers to be carried. The 800s (excepting the 806s) were powered by the Dart 510.

The third type of Viscount was the 810. It was the same size as the 800s, but was powered with R.Da. 7/1 Mk 225 or Mk 530 Darts. With the greater power, the 810 was faster and longer ranged than the 800.

Proposed type 740, 850, and 870 Viscounts never left the drawing board.

The Viscount's good performance and popularity with customers encouraged Vickers to privately finance and develop an enlarged and re-engined variant of the Viscount, later designated as the Vickers Vanguard.

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Operational history

Regular passenger flights were launched by BEA on 18 April 1953, the world's first scheduled turboprop airline service. BEA became a large user of the Viscount; by mid-1958, BEA's Viscount fleet had carried over 2.75 million passengers over 200,000 flight hours. Following BEA's launch of the type, multiple independent charter operators, such as British Eagle, were quick to adopt the Viscount into their fleets. During the 1960s, the Viscount formed the backbone of domestic air travel in Scotland.

thumb|left|Viscount 700 prototype G-AMAV as competitor No. 23 in the NZ Air Race at London Airport, 8 October 1953

The early operational service of the Viscount quickly proved it to have significant performance advances over its rivals, and orders rapidly rose as a result; up to November 1952, only 42 aircraft had been ordered; by the end of 1953, the order book had risen to 90, and 160 by the end of the following year. Vickers was able to quickly respond to the new orders, as it had gambled on such orders emerging and early on the decision had been taken to commit to a high production rate at the company's own risk. In 1957, the Vickers production line was producing the Viscount at a rate of one aircraft every three days.

In October 1953, the Viscount 700 prototype G-AMAV achieved the fastest time (40 hours 41 minutes flying time) in the transport section of the 12,367 mi (19,903 km) air race from London to Christchurch, New Zealand. The aircraft averaged 320 mph (520 km/h) in the event, crossing the finish line nine hours ahead of its closest rival, a Douglas DC-6A of KLM, with the latter winning on handicap. En route, equipped with extra fuel tanks, it flew 3,530 mi (5,680 km) nonstop from the Cocos (Keeling) Islands to Melbourne's Essendon Airport in 10 hours 16 minutes (343.8 mph).

Trans Australia Airlines (TAA) received its first Viscount in 1954, and the aircraft quickly proved profitable, leading to additional orders. The Viscount proved to be an invaluable aircraft for TAA, aviation author John Gunn stating, "TAA had achieved dominance on Australia's trunk routes with its turboprop Viscounts". TAA procured over a dozen Viscounts, and purchased later turboprop aircraft such as the Fokker F27 Friendship; It later transitioned to jet aircraft as passenger demand outgrew the capacity of the Viscounts. the Viscount allowed Ansett to set out a faster and superior service than the larger TAA for the first time. The Two Airlines Policy was formally established in 1952 by the Fifth Menzies Ministry. The policy took practical effect when Ansett purchased the failing Australian National Airways in 1957, resulting in it being the only competitor for the government-owned TAA. Unstated was the requirement for both airlines to have identical equipment.

thumb|Trans-Canada Airlines Viscount making a low pass sometime in the 1960s

The first North American airline to use turboprop aircraft was Trans-Canada Air Lines (TCA), with a small fleet of Type 700 Viscounts. Initially, TCA was cautious of the Viscount due to the turboprop engine being a new technology, and a preference had existed for acquiring the piston-engined Convair CV-240, instead; praise of the Viscount from pilots and a promise from Vickers to make any design changes desired by TCA persuaded it to procure the Viscount, instead. On 6 December 1954, the first Viscount was delivered to Canada in a large media event that included an improvised aerial display.

TCA became a prolific operator of the type, placing multiple follow-up orders for additional Viscounts. By 1958, TCA had an operational fleet of 51 Viscounts. Aviation author Peter Pigott later wrote: "For TCA and Vickers, the Viscount was a public-relations coup. Passengers loved the quiet ride and panoramic windows. No other airline in North America flew turbo-prop airliners then, and no other British aircraft was bought by American airlines in such quantity." TCA operated the Viscount for two decades until Air Canada (TCA relabelled with a name equally at home in English and French), ended Viscount services in 1974. The type was replaced by the McDonnell Douglas DC-9. US Capital Airlines became an important operator of the Type 700 Viscount,