The A.V. Roe & Company (Avro) 707 was a tailless, 'proof-of-concept' thick delta design, that was principally the work of Stuart D. Davies, Avro Chief Designer. It was the experimental investigation into the aerodynamics and low speed characteristics for the design of the 698 jet bomber and of which little was known at the time. Effectively, it was a one-third scale version of what was to become the Avro 698 Vulcan.
The prototypes were ordered by the Ministry of Supply to Specification E.15/48 and were produced very quickly, utilising components from other aircraft such as the first prototype using a Gloster Meteor canopy.
The diminutive experimental aircraft initially incorporated a 50° sweep delta wing, without a horizontal tail on a fin with trailing edge sweep. The wing carried two pairs of control surfaces with inboard elevators and outboard ailerons. Retractable air-brakes were fitted above and below the wings.
All Avro 707 aircraft were powered by a single Rolls-Royce Derwent centrifugal turbojet with the air intake on the first and second prototypes being located on the upper rear fuselage.
The first Avro 707 (VX784) was built at Woodford and flew for the first time at Boscombe Down on 4th September 1949, with S.E. 'Red' Esler in the cockpit. It was notable that this was only the second ever flight by a delta wing jet aircraft and the first built in Britain. Within just a few days the aircraft had accumulated enough hours to allow it to appear in the New Type Park at that years SBAC Show at Farnborough.
The first prototype was very short lived however as it crashed on 30th September 1949, near Blackbushe just over 3 weeks after its debut flight. The following official investigation absolved any blame on the delta wing concept, concluding that there was a suspected control circuit failure, causing the air brakes to be locked open and creating the stall. Sadly, Test Pilot Esler was killed upon impact.
Despite a short delay during the accident investigation, work continued at Woodford and a number of modifications were introduced to the second prototype in order to save time and simplify the construction. The long pointed nose section intended for the Type 707A was grafted onto the fuselage, extending the aircraft to 12 ft (3.66 m) longer than the original. Other changes included change to the degree of wing leading edge sweep, modified elevators and air brakes. A Gloster Meteor cockpit canopy, Avro Athena main undercarriage and a lengthened Hawker P.1052 nose leg were also incorporated in the design.
Redesignated Type 707B (serial VX790), the second aircraft achieved its maiden flight at Boscombe Down on 6th September 1950.
Visually and most notable was the longer nose wheel leg, designed to provide the high angle of incidence required by deltas for landing and take off. The Avro 707B was given the same dorsal engine intake as the Avro 707, although this was later modified to a NACA design.
A third aircraft (WD280), which was confusingly designated Avro 707A, was then built at Woodford for higher-speed testing.
Experience with the dorsal intake of the second aircraft had revealed that as speed increased, the cockpit induced turbulence which interrupted the intake airflow. In order to overcome this, the intakes on the Avro 707A were moved to the wing roots. Consequently, when the Avro 698 Vulcan appeared, it looked very much like an enlarged 707A.
Later, the Avro 707A (WD280) was also utilised to test the compound leading edge sweep, subsequently also used on all Avro 698 Vulcan aircraft. Although by now, the first Avro 698 Vulcan prototype was already flying, having flown at Woodford on 30th August 1952, a second Avro 707A (WZ736) was built at the AV Roe Repair Factory at Bracebridge Heath, Lincolnshire. This Avro 707A made its maiden fight on 20th February 1953.
The final variant of the type was the two-seat Avro 707C and initially four examples were ordered into production (at Bracebridge Heath) by the RAF. These were slated for 'Orientation Training' concentrated around flying aircraft with the new delta wing configuration, and they featured 'side-by-side' seating, with dual-controls. The production order was later cancelled and only the prototype (WZ744) was built.
The Avro 707C had its maiden flight on 1st July 1953 and was ultimately employed in other research that did not involve the Avro 698 Vulcan development.
All of the five Avro 707 aircraft provided valuable insights into the flight characteristics, most of the information coming from the second and third prototypes which flew before the Avro 698 Vulcan.
Even after the Avro 698 Vulcan research was concluded, the four surviving Avro 707 variants resplendent in individual bright blue, red, orange and silver (natural metal) colour schemes, still played significant roles as research aircraft.
After the compound sweep investigations they all spent a period at the Royal Aircraft Establishment (RAE) Farnborough carrying out handling trials, especially in the field of powered controls. The first of the Avro 707A's (VX790) went to the Aeronautical Research Laboratories (ARL) in Australia where it was used for low-speed delta wing airflow measurements.
The second 707A (WD280) was also sent to the RAE from June 1953, allocated for aerodynamic trials and automatic control investigations.
The Avro 707B (VX790) joined the RAE in September 1952 and was one of the aircraft used by the Empire Test Pilots School (EPTS) from January to September 1956. Unfortunately, it was damaged on landing and broken up at RAE Bedford.
The two-seat Avro 707C (WZ744) joined the RAE in January 1956 and was involved in substantial research into the development of fly-by-wire control systems. This was the first aircraft of its kind to be fitted with a side stick controller and it was still flying in September 1966, when it achieved its full airframe time and entered enforced retirement.
In addition to the static appearance at Farnborough in 1949, all of the remaining Avro 707 variants made public appearances in both September 1952 and 1953.
In 1952, the first prototype Avro 698 Vulcan flew alongside the Avro 707A and Avro 707B.
The ultimate appearance occurred in 1953 however, when all four surviving Avro 707 variants flew alongside the first two Avro 698 Vulcan prototypes.
One aircraft (VX784) with Derwent 5 engine, ‘saddle’ type dorsal engine air intake behind the cockpit. Unpainted finish.
Two aircraft with Derwent 8 engine, modified wing section, wing root engine air intakes, control surfaces extensively modified.
One (WD280) finished in pink, then repainted bright red – later silver. Second aircraft (WZ736) finished in orange overall.
|Avro 707B||One aircraft (VX790) to replace the original Avro 707. Longer more-pointed fuselage, Derwent 5 engine and dorsal engine air intake. Painted bright blue overall.|
|Avro 707C||Side-by-side dual-control trainer version of 707A with widened forward fuselage. Derwent 8 engine, wing root engine intakes. One aircraft (WZ744) completed, finished in silver. One other aircraft (WZ739) cancelled.|
|Powerplant||One Rolls-Royce Derwent 8 turbojet of 3,600 lb (1,633 kg) st|
|Span||34 ft 2 in (10.41 m)|
|Maximum Weight||9,500 lb (4,309 kg)|
|Maximum Speed||477 mph (768 km/h, 415 knots)|
|Prototype (XV770 / XV777)||1|
|Avro 707A (WD280 / WZ736)||2|
|Avro 707B (VX790)||1|
|Avro 707C (WZ744)||1|
|Avro 707A (WZ736)||Museum of Science and Industry, Manchester|
|Avro 707A (WD280)||
RAAF Museum at Point Cook, Victoria
|Avro 707C (WZ744)||
RAF Museum, Shrifnall, Cosford