Armstrong Whitworth Apollo

__NOTOC__ Infobox Aircraft
name=AW.55 Apollo


caption=
type=Four-engined turboprop airliner
manufacturer=Armstrong Whitworth
designer=
first flight=1949
introduced=1952
retired=1957
status=
primary user=Aeroplane & Armament Experimental Establishment
more users=Empire Test Pilot's School
produced=
number built=2
variants with their own articles=The Armstrong Whitworth AW.55 Apollo was a 1940s British airliner built by Armstrong Whitworth at Baginton. The aircraft was in competition with the Vickers Viscount but beset with engine problems only two were built.

Development

The requirement resulted from the Brabazon Committee's Type II design, calling for a small-sized medium-range pressurized aircraft to fly its less-travelled routes which became Air Ministry Specification C.16/46 for an aircraft able to carry 24-30 passengers over 1,000 miles (1,609km) at a cruising speed of 300mph.

The resulting design was the AW.55 Apollo, a low-wing cantilever monoplane with a tricycle retractable landing gear. It had a conventional tail unit with a mid-placed cantilever horizontal tailplane. It had a pressurised fuselage with seating for 26 to 31 passengers. It was designed to use the Armstrong Siddeley Mamba which was expected to produce 1,270 shp for the production aircraft. When the prototype Apollo was ready to fly the engine could only produce 800shp. Two prototypes and a static test fuselage were ordered by the Ministry of Supply and construction started in 1948. The prototype (serial "VX220") first flew from Baginton on 10 April 1949. The aircraft was unstable and underpowered and after just nine hours of test flying it was grounded to try and solve some of the problems. Test flying resumed in August 1949 but the aircraft had further engine problems. Changes were made to the design of the tail unit including fitting a dorsal fin and increasing the fin area to improve the flying qualities. In October 1950 a limited category Certificate of Airworthiness was granted to allow the aircraft to carry non-fare paying passengers. One trial flight between Baginton and Paris was carried out in 12 March 1951 . Further engine problems stopped the trial and test flights. The company started a selling campaign to European airlines but the problems with performance and continual engine difficulties it was decided to abandon development of the aircraft in June 1952. The competing Brabazon IIB design the Vickers Viscount powered by the Rolls-Royce Dart became a best-selling turboprop in the 1950s and 60s.

Operational history

Although the development program was cancelled the two prototypes had been paid for by the Ministry of Supply and the prototype aircraft entered service at the Aeroplane & Armament Experimental Establishment at Boscombe Down in September 1952. The second aircraft followed in September 1953 and was later used by the Empire Test Pilot's School. The prototype was broken up in 1955 and the second aircraft was passed to the Structures Department at RAE Farnborough. The aircraft fuselage was used at Farnborough for water tank pressure testing until it was scrapped in the 1970s.

Operators

;UK
*Aeroplane & Armament Experimental Establishment
*Empire Test Pilot's School

pecifications

aircraft specifications

plane or copter?=plane
jet or prop?=prop

ref=British Civil Aircraft since 1919 [A.J. Jackson, "British Civil Aircraft since 1919" Volume 1, 1974, Putnam, London, ISBN 0 370 10006 9, pp 285] , British Aircraft Directory [ [http://www.britishaircraft.co.uk/aircraftpage.php?ID=125 Apollo] ]

crew=3
capacity=26 - 31 passengers
payload main=7,500 lb
payload alt=3,402 kg
length main= 71 ft 6 in
length alt=21.79 m
span main=92 ft
span alt=28 m
height main=26 ft
height alt=8.0 m
area main= 986 ft²
area alt= 91.6 m²
airfoil=
empty weight main=30,800 lb
empty weight alt= 13,600 kg
loaded weight main=
loaded weight alt=
useful load main=
useful load alt=
max takeoff weight main= 45,000 - 47,000 lb
max takeoff weight alt= 20,400 kg
more general=

engine (prop)=Armstrong Siddeley Mamba AS.1 [From July 1951, Mk 504 ]
type of prop=axial flow turboprop
number of props=4
power main= 1,010 shp
power alt=750 kW
power original=

propeller or rotor?=propeller
propellers=
number of propellers per engine=
propeller diameter main=
propeller diameter alt=

max speed main= 330 mph
max speed alt=
cruise speed main= 276 mph [ [http://www.aviastar.org/air/england/arm_apollo.php Armstrong Whitworth A.W.55 Apollo - medium-range transport ] ]
cruise speed alt= 444 km/h
stall speed main=
stall speed alt=
never exceed speed main=
never exceed speed alt=
range main= 940 miles
range alt=1,500 km
ferry range main=
ferry range alt=
ferry range more=
ceiling main= 28,000 ft
ceiling alt= 8,500 m
climb rate main= 1,500 ft/min at sea level
climb rate alt= 7.6 m/s
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=

avionics=

ee also

aircontent
see also=
related=
similar aircraft=
*Airspeed Ambassador
*Vickers Viscount
lists=

References

* A.J. Jackson, "British Civil Aircraft since 1919" Volume 1, 1974, Putnam, London, 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

External links

http://www.britishaircraft.co.uk/aircraftpage.php?ID=125http://www.aviastar.org/air/england/arm_apollo.php