Armstrong Whitworth AW.660 Argosy

The Armstrong Whitworth Argosy was a British post-war transport/cargo aircraft; it was the final aircraft to be designed and produced by aviation company Armstrong Whitworth Aircraft. Although given different internal design numbers, the "AW.650" civil and "AW.660" military models were, for most practical purposes, the same design, while both models also shared the "Argosy" name.
Development of the Argosy originates in the "AW.66", a proposed twin-engined military transport that was designed with British Air Ministry's Operational Requirement 323 (OR323) in mind. While Armstrong Whitworth terminated work on the AW.66, it decided to go forward with a civilian-oriented derivative of the design, designated "AW.65", as it was judged to be commercially viable. The AW.65 was redesigned to use four Rolls-Royce Dart turboprop engines, and thus was re-designated as the "AW.650". On 8 January 1959, the first Argosy conducted the type's maiden flight. On December 1960, the type received Federal Aviation Administration (FAA) type certification, enabling the initial civil version, referred to as the "Series 100", to enter civil service across most parts of the world.
In Britain, military planners took interest in the Argosy and released a new specification for a militarised variant, designated "AW.660". First flown on 4 March 1961, this model featured double the range of the "Series 100" and otherwise differed by an alternative door arrangement, which was largely to facilitate paratroop operations. Furthermore, an improved civil variant, the "Series 200", was introduced at the behest of airline British European Airways (BEA). First flown on 11 March 1964, this model featured a new wing incorporating a fail safe structure, being stronger and lighter than its original counterpart. The Argosy was operated by both the Royal Air Force (RAF) and various civil operators across the globe for numerous years. The type was withdrawn from RAF service during 1978, while the last Argosy was retired from civil operations during 1991.
Development.
Background.
The development of the Argosy can be traced back to the development of Operational Requirement 323 (OR323) by the British Air Ministry. During 1955, a specification was issued based upon OR323, which sought a medium-range freight aircraft that would be capable of lifting a maximum payload of 25,000 lb (11,340 kg), while also possessing a range of when carrying up to . British aviation manufacturer Armstrong Whitworth Aircraft took interest in this specification and decided to allocate members of its design team to the task of developing a suitable aircraft to meet its demands. Initially, design efforts were focused upon a twin-engine design intended for military use, which was internally designated as the "AW.66".
As it was recognised that the aircraft held sales potential within the civil market, a civilian-oriented variant, designated "AW.65", was also designed alongside the military design; the AW.65 principally differed from the AW.66 via the installation of full-section doors at each end of the fuselage to enable rapid loading and unloading operations. However, a lack of available finance contributed to the company's decision to abandon all work towards meeting the military requirement; despite this setback, Armstrong Whitworth had already decided to proceed with developing the civil variant as a private venture. The company believed that the type would have significant appeal to the growing short-haul air freight sector of both the European and American markets. At that time, no other aircraft had been purpose-designed for such a purpose. As work continued, the AW.65 was extensively redesigned, including the adoption of four Rolls-Royce Dart turboprop engines; the resulting aircraft being designated as the "AW.650".
On 8 January 1959, the first Argosy performed its maiden flight. It appeared during that year's Farnborough Airshow, by which point five aircraft were flying, having cumulatively amassed about 400 flight hours between them. Certification-related testing of the type was reportedly completed during September 1960. In December 1960, the Argosy received type certification from the American Federal Aviation Administration (FAA), authorising the aircraft's entry to commercial service. 10 of the initial civil version, the Series 100, were built; construction of these aircraft had commenced months prior to receiving certification so that deliveries could commence as soon as possible.
Further development.
While the RAF had lost interest in any acquisition of the original AW.66 design, the service still needed to procure a replacement for its obsolete piston engined transport fleet, including the Vickers Valetta and Handley Page Hastings. During 1959, the British Air Ministry released a new specification that called for a military derivative of the AW.650, the envisioned aircraft was intended to serve in multiple roles, including as a medium-range transport, paratroop and supply aircraft. The resultant design, which was designated "AW.660", was significantly different from the AW.650. Changes included the sealing of the nose door, its location being instead occupied by the radome of a weather radar unit, while the rear doors were substituted for by an alternative clamshell style which incorporated an integral loading ramp, while a stronger cargo floor was also installed. A pair of additional doors were fitted, one each on the starboard and port sides, which enabled paratroopers to exit. The military Argosy was powered by an arrangement of four Rolls-Royce Dart 101 turboprops and possessed twice the range of the civil Series 100. From July 1960, the second Argosy Series 100 was used to flight-test the new clamshell door design. On 4 March 1961, the first of the 56 Argosies destined for RAF service performed its first flight.
Early on, civil operator British European Airways (BEA) had shown open interest in the Argosy, the company viewed the aircraft as a potential replacement for its existing piston engined freighters; however, evaluations of the Series 100 soon found that its payload capacity would not allow for the type to operated profitably. Early on, as a measure taken to reduce design costs, the wing of the Argosy had been based on that of the Avro Shackleton, a maritime patrol aircraft that was developed and built by another entity within the Hawker Siddeley Group; in order to satisfy BEA's requirements, a new wing was designed which shared the same aerodynamic design, but benefitted from a more modern "Fail safe" structure rather than the Safe-life design used on the earlier wing. This change resulted in a wing that was both stronger and lighter, but was also no longer limited in terms of its fatigue life. The revised version, designated as the "Series 200", also featured several other improvements, including the adoption of enlarged cargo doors, integral wing fuel tanks and a modified landing gear arrangement. The Series 200 reportedly had better handling than the older Series 100, although some aerodynamic refinements were required during testing.
On 11 March 1964, the first Series 200 aircraft conducted its first flight; it was soon followed by six more Series 220s, which were outfitted with more powerful engines. While work had commenced upon another Series 220, this airframe was never completed and was ultimately scrapped. According to aviation periodical Flight International, the Argosy had been negatively impacted by the emergence of the long-haul passenger jet, as many surplus propeller-driven aircraft had been converted to freighters during this era, thus driving down both demand and prices for new-build cargo aircraft.
Design.
The Armstrong Whitworth Argosy was a general-purpose transport aircraft largely used for freight operations by both military and civil operators. At the time of its introduction, the type was considered to be unique in its class. Principally designed as a freighter, the aircraft could also be used for other tasks. The Argosy was offered in a convertible configuration for carrying both freight and passengers; the civil variant could accommodate a maximum of 80 passengers while providing comfort and speed conditions comparable to the contemporary Vickers Viscount airliners. In the cargo role, the Argosy was designed for rapid turnaround times of only 20 minutes without the use of lifting trucks or cranes, utilising pallets and rollers to eliminate packaging.
In terms of its basic configuration, the Argosy's tailplane was mounted on twin booms that ran rearwards from the inner engine nacelles, leaving the cargo doors at the rear of the fuselage clear for straight-in loading. Sideways-opening doors were fitted at both ends of the fuselage and the flight deck was set above the freight hold. This configuration allowed for an unobstructed cargo space measuring with a sill height corresponding to that of a normal flatbed truck. It had a maximum weight of 88,000 lb (39,915 kg) and a payload of 28,000 lb (12,700 kg). When cruising at 276 mph (444 km/h), it had a range of 1,780 mi (2,865 km) and could seat a maximum of 89 passengers.
The Argosy was powered by four Rolls-Royce Dart turboprop engines with Rotol-built four-blade propellers. The power rating of the engines depended on the aircraft variant. The sound produced by the Dart engines combined with its relatively unusual "pod and boom" basic configuration, which was similar to the earlier C-82 Packet and C-119 Flying Boxcar transport aircraft, has been attributed as the source of the type's nickname "The Whistling Wheelbarrow".
Operational history.
Civil use.
The Argosy Series 100 first entered service with the American cargo airline Riddle Airlines. Early on, Riddle had expressed interest in the type, having ambitions to use the type to meet contracts to provide logistics support to the United States Air Force (USAF) within the domestic United States. During late 1960, Riddle purchased a batch of seven Argosies for this purpose. However, when Riddle lost the logistics contract during 1962, its Argosies were repossessed by Armstrong Whitworth and subsequently sold onto other airlines, some of which had taken over the contracts previously being served by Riddle.
As a stopgap measure, BEA had ordered Armstrong Whitworth's three remaining Series 100s, intending to use them until the airline could receive its definitive Series 220s; during 1964, BEA had placed an order for five such aircraft. Reportedly, the Argosy had contributed to BEA possessing a superior air freighting ability to any other airline operating in the region, the type's double-end loading capability being a viewed as a crucial part of its economics. During its operations of the type, the airline lost two Series 220s in separate crashes, choosing purchase another Argosy to replace the first lost aircraft. Reportedly, BEA's small fleet of Argosies was found to be unprofitable, even when BEA introduced the more-capable Series 220s; this has been attributed to BEA procedures relating both to safety and general operations. During April 1970, BEA opted to withdraw its Argosy fleet, choosing to replacing the type using a freighter conversion of its Vickers Vanguards.
Two aircraft were operated by SAFE Air in New Zealand, where they formed the main link between the Chatham Islands and the mainland; these aircraft were fitted with a pressurised "passenger capsule". During April 1990s, one of these aircraft was damaged beyond repair as a result of a landing accident; a third Argosy was leased by SAFE Air from Australian company Mayne Nickless for five months during 1990 as a short-term replacement. During September 1990s, the final flight of a New Zealand Argosy was conducted by operator SAFE Air; the aircraft itself was retired and is presently being preserved by volunteer owners near Woodbourne Airport, Blenheim, New Zealand.
During 1991, the last operational Argosies, which was being flown by American cargo airline Duncan Aviation, were withdrawn, marking the end of the type's flying history.
Military use.
During the 1960s, the Argosy was procured for the Royal Air Force (RAF), the first of which entering service in March 1962. The service frequently made use of its capability to accommodate up to 69 troops, 48 stretcher cases or of freight. Operationally, it could carry various items of military equipment, including combat vehicles such as the Saracen or Ferret armoured cars, or artillery such as the 105 mm (4.13 in) howitzer or Wombat. However, subsequent design changes to both the Saracen and the Argosy's mainspar (which ran throughout the top of its cargo bay) subsequently precluded the use of the Argosy as a Saracen transport.
During 1962, the earliest deployment of the Argosy was recorded as being performed to 105 Squadron, which was stationed in the Middle East, along with 114 and 267 Squadrons, based in the UK at RAF Benson. The following year, 215 Squadron received its Argosies, which were stationed at RAF Changi, Singapore. However, this squadron was disbanded on New Year's Eve 1967, its aircraft being re-allocated to 70 Squadron, based at RAF Akrotiri, Cyprus. 70 Squadron would be the final squadron to operate the aircraft in the transport role, retiring its last Argosy during February 1975. During December 1970, the RAF had begun receiving American-built Lockheed Hercules transport planes, which progressively replaced the Argosy fleet in the transport role. Between 1968 and 1978, the E.1 variant of the Argosy, which was used in the calibration role, was flown by 115 Squadron, which was based at RAF Cottesmore for much of this time period.
Variants.
Armstrong Whitworth AW 650 Argosy (1959).
A total of 17 were built for civil operators Riddle Airlines (Series 101) and British European Airways (series 102 and 222).
10 Series 101 and 102 aircraft were built. Seven Series 200 aircraft were built (the eighth was not completed); the series 200 had a larger freight hold and enlarged front and rear doors to enable it to carry standard size cargo pallets. The series 200 also had a lighter redesigned wing increasing the maximum range and Rolls-Royce Dart 532/1 turboprops.
Armstrong Whitworth AW 660 Argosy / Argosy C Mk 1.
Additional differences to the civil variants:
56 aircraft were produced for the RAF under the designation Argosy C Mk 1 (C.1), it served in a total of six squadrons; three based in the UK and one each in Aden, Cyprus, and the Far East. The RAF withdrew the Argosy from transport missions during 1975 as an economic measure. Those aircraft not scrapped or retained were sold to commercial operators.
Hawker Siddeley Argosy E Mk 1.
During 1963, Hawker Siddeley Group dropped the names of its component companies, rebranding its products under the Hawker Siddeley banner. To meet a requirement for a RAF flight inspection aircraft, nine Argosy C.1s were modified in 1971 as the Argosy E.1. These were a regular sight at British military airfields, being operated by 115 Squadron until they were replaced by the Hawker Siddeley Andover during 1978.
Hawker Siddeley Argosy T Mk 2.
After the removal of the Argosy C.1 from the cargo/transport role, it was decided to modify 14 aircraft as Navigation Trainers for RAF Training Command, which were intended to replace the Vickers Varsity. One aircraft "XP411" was re-designated as the Argosy T Mk 1 in advance of delivery of the T Mk 2 fleet. Only two aircraft ("XP447" and XR136) were modified as the Argosy T.2, but they were not successful, the programme having been abandoned as a consequence of defence spending cuts.