Armstrong Whitworth Apollo

Armstrong Whitworth Aircraft

Industry	Aerospace
Founded	1919
Headquarters	Coventry , United Kingdom
Products	Aircraft

The Armstrong Whitworth AW.55 Apollo was a British four-engine turboprop airliner developed during the late 1940s by Armstrong Whitworth at Baginton (Coventry Airport). Intended as a competitor to the Vickers Viscount, the aircraft suffered from persistent engine difficulties, resulting in only two units being constructed.

Development

The project originated from the Brabazon Committee’s Type II specification, which outlined the need for a small, pressurized, medium-range airliner to serve less busy routes. This requirement was formalised as Air Ministry Specification C.16/46, calling for an aircraft capable of transporting between 24 and 30 passengers over approximately 1,000 mi (1,600 km) at a cruising speed near 300 mph (480 km/h).

The design that emerged was the AW.55 Apollo, a low-wing cantilever monoplane featuring retractable tricycle landing gear. Due to the slim profile of its engines, there was insufficient space within the nacelles for housing the main wheels; consequently, these retracted into the wings instead. The aircraft incorporated a conventional tail assembly with a mid-mounted cantilever horizontal tailplane and a pressurized cabin accommodating 26 to 31 passengers. Power was initially planned to come from the Armstrong Siddeley Mamba ASM.2 engines, expected to deliver 1,270 shp (950 kW) plus an additional 307 lbf (1,370 N) of static thrust for production models; however, at prototype stage, the engines only managed around 800 shp (600 kW).

Construction commenced in 1948 following an order from the Ministry of Supply for two prototypes—one fully equipped—and a static test fuselage. The first prototype (serial number VX220) completed its maiden flight on 10 April 1949, departing from Baginton’s grass airfield near Coventry for a 30-minute trial.

Initial testing revealed that the aircraft was both underpowered and exhibited instability issues. After accumulating just nine flight hours, it was grounded to address these challenges. Flight trials resumed in August 1949 but were again hampered by engine reliability problems. Modifications were implemented to enhance stability, including enlarging the fin area and adding a dorsal fin to the tail unit.

In October 1950, the Apollo received a limited category Certificate of Airworthiness permitting it to carry non-paying passengers. A notable proving flight took place on 12 March 1951, covering the route between Baginton and Paris in one hour and twenty-six minutes.

Ongoing engine complications ultimately curtailed further testing and demonstration flights. Despite efforts to market the aircraft across European airlines, persistent performance shortcomings led to the cessation of development in June 1952. Meanwhile, the rival Brabazon IIB design—the Vickers Viscount powered by Rolls-Royce Dart engines—achieved significant commercial success throughout the 1950s and 1960s. The second Apollo prototype was intended to be equipped with Mamba 3 engines to support a maximum takeoff weight of 45,000 lb.

Operational history

Despite the cancellation of the development program, funding for the two prototypes had already been provided by the Ministry of Supply. The first prototype was delivered to the Aeroplane & Armament Experimental Establishment at Boscombe Down in September 1952. The second prototype, bearing serial VX224, arrived in September 1953 and was subsequently utilized by the Empire Test Pilot's School in 1954 for training pilots on multi-engine aircraft. The initial prototype was dismantled in 1955, while the second was transferred to the Structures Department at RAE Farnborough. At Farnborough, the fuselage served as a test rig for water tank pressure experiments until its disposal in the 1970s.

Operators

Template:UK

• Aeroplane & Armament Experimental Establishment
• Empire Test Pilot's School

References

• A.J. Jackson, British Civil Aircraft since 1919:Volume 1. London:Putnam, 1974. ISBN 0-370-10006-9. pp 285
• King, Derek. "The Armstrong Whitworth Apollo". Air-Britain Aviation World Vol 56 No. 4 Winter 2004, pp 164–165.ISSN 1742-996X
• Tapper, Oliver. Armstrong Whitworth Aircraft since 1913. London:Putnam, 1988. ISBN 0-85177-826-7.

External links

• "Apollo" an article from Flight published in 1948