Avro 707

Avro

Industry	Aerospace
Founded	1910 in United Kingdom
Founder	Alliot Verdon Roe
Headquarters	United Kingdom
Products	Aircraft

Not to be confused with Boeing 707.

Template:Infobox aircraft The Avro 707—also referred to as the Type 707—was an experimental aircraft crafted and manufactured by the British firm Avro.

Its primary purpose was to evaluate the tailless thick delta wing design selected for the Avro 698 jet-powered bomber, which was subsequently named the Avro Vulcan. At that time, the low-speed flight behavior of such configurations was not thoroughly understood. Aerodynamically, the Avro 707 represented approximately one-third the scale of the Vulcan. The second prototype, designated VX790, was constructed to the 707B standard, featuring an extended nose, a redesigned cockpit canopy, a wing with a (51°) sweep angle, and a lengthened nose landing gear leg to increase the angle of incidence during takeoff and landing. The final variant, the twin-seat 707C, was intended for delta wing orientation training with the Royal Air Force; however, no production models were ever manufactured. The limited number of Avro 707s built were primarily utilized for flight testing.

The inaugural flight occurred on 4 September 1949 at RAF Boscombe Down, followed soon after by low-speed trials. Higher speed evaluations began in late 1953 using the third aircraft, the first 707A. After completing development of the Vulcan, the four remaining Avro 707s continued operating as general research platforms. The prototype 707C participated in various research initiatives mostly unrelated to the Vulcan project. Testing efforts involved both the Royal Aircraft Establishment (R.A.E) and Australia's Aeronautical Research Laboratories. During the early 1950s, the Avro 707 made several appearances at the Farnborough Airshows. The final operational Avro 707 was retired from flight in 1967; three units have been preserved and are exhibited in museums.

Design and development

File:Avro 707A WD280 in flight c1951.jpg

An Avro 707A airborne in 1951.

Conceived as a "proof-of-concept" delta wing aircraft, the Avro 707 was principally designed by Stuart D. Davies, Avro’s lead designer. This relatively small aircraft initially featured a wing swept approximately at 50°, lacking a horizontal tail but mounted on a fin with swept trailing edges. Along this trailing edge were two pairs of control surfaces: elevators positioned inboard and ailerons outboard. These control surfaces operated alongside a conventional rudder. Retractable airbrakes were installed above and below each wing surface. The structure employed all-metal stressed-skin construction.

The Ministry of Supply commissioned the prototypes under Specification E.15/48, which required a low-speed research aircraft representing a one-third scale model of Avro’s B.35/46 strategic bomber design—the precursor to the Vulcan. To expedite production, components were sourced from existing aircraft; for example, the canopy on the first prototype originated from a Gloster Meteor. Additional off-the-shelf parts included an Avro Athena main undercarriage leg and Gloster Meteor nose gear strut. The data gathered from these test aircraft—especially from the second and third prototypes that flew prior to the Vulcan—provided critical insights into its flight characteristics. Plans for a half-scale version called the Avro 710 were abandoned once it became evident that developing a high-speed variant of the Avro 707 would be more efficient.

Every Avro 707 was powered by a single Rolls-Royce Derwent centrifugal turbojet engine. On both the initial prototype and later 707B, air intakes were positioned atop the rear fuselage. Some units were equipped with ejection seats for pilot safety. A total of five Avro 707 aircraft were completed, with three continuing to fly after the Vulcan’s maiden flight on 30 August 1952.

Operational history

File:Avro 707 Farnborough 1951.jpg

The Avro 707B at Farnborough, in 1951.

The initial Avro 707, registered VX784, took to the skies for its inaugural flight on 4 September 1949 at MOD Boscombe Down, piloted by Squadron Leader Samuel Eric Esler, DFC, AE. Shortly after, it was exhibited statically at the Farnborough Airshow two days later. Unfortunately, the first prototype's testing phase was abruptly ended when it crashed near Blackbushe on 30 September 1949 during a test sortie, resulting in the death of Esler. This tragic event prompted a temporary suspension of the second prototype's construction while the design underwent thorough reassessment and multiple improvements were introduced.

The subsequent prototype, VX790, which was redesignated as the 707B, featured several modifications including an extended nose, a redesigned cockpit canopy, a wing with a different sweep angle of 51°, and an elongated nose landing gear leg to achieve the elevated angle of incidence necessary for delta wing takeoffs and landings. Initially, the Avro 707B retained the dorsal engine intake from the original model, but this was later replaced with a NACA style intake. Its maiden flight occurred on 6 September 1950, quickly demonstrating relatively stable handling characteristics. Both the original 707 and the 707B primarily served to evaluate low-speed flight behavior.

The third aircraft, designated 707A and bearing registration WD280, was developed specifically for high-speed testing. Experience gained from the dorsal intake design of the earlier models revealed that increasing speeds caused airflow disruption due to turbulence generated around the cockpit area. To address this, the air intakes were relocated to the wing roots. This variant was not intended for supersonic operation as such performance would require both powered flight controls and significantly more powerful engines. The Avro Vulcan bore a strong resemblance to a scaled-up version of the 707A when it appeared. The 707A also played a key role in testing compound leading edge sweep angles that were later incorporated into all Vulcan bombers. Although the first Vulcan prototype had already flown, a second 707A, registered WZ736, was produced to accelerate development efforts. It completed its first flight on 20 February 1953.

The last variant introduced was the two-seat 707C. Initially, four units were ordered by the RAF to facilitate orientation training for pilots transitioning to delta-winged aircraft. The 707C featured an expanded cockpit with side-by-side seating and dual control setups. However, this production order was cancelled after one prototype, WZ744, had been built. Its maiden flight took place on 1 July 1953, and it eventually contributed to research projects unrelated to Vulcan development.

File:Avro Vulcan VX770 VX777 FAR 13.09.53 edited-2.jpg

Two Avro 707As, a 707B and a 707C alongside both Vulcan prototypes at the SBAC Farnborough Air Show in September 1953

Following completion of Vulcan development, all four remaining Avro 707 aircraft—each painted in distinctive bright blue, red, orange, and natural metal silver liveries—remained active as experimental platforms. After investigations into compound sweep angles, and subsequent handling trials involving powered flight controls at the Royal Aircraft Establishment (R.A.E), one of the 707As was transferred to Australia's Aeronautical Research Laboratories for studies on low-speed delta wing airflow dynamics. The other 707A also joined R.A.E in June 1953 for aerodynamic research and later experiments with automatic control systems.

In September 1952, the Avro 707B became part of R.A.E.'s fleet, serving as one of several aircraft utilized by the Empire Test Pilots School between January and September of 1956, before sustaining landing damage that led to its dismantling at R.A.E Bedford. The two-seat 707C joined R.A.E in January of that year; its most notable contribution was advancing early fly-by-wire control technology using a side-stick controller configuration. This aircraft remained operational with R.A.E until September 1966 when it reached its maximum airframe service life.

Throughout the decade of the 1950s, Avro 707s frequently appeared at the Farnborough Airshow. In particular during 1952, they operated alongside the first Vulcan prototype models 'A' and 'B', while in the following year all four surviving Avro 707s flew together with both initial Avro Vulcan prototypes at Farnborough’s SBAC event.

Surviving aircraft

File:Avro 707A WZ736 MSIM 10.08.85R edited-2.jpg

The second Avro 707A WZ736 exhibited alongside an Avro Shackleton at the Museum of Science and Industry in Manchester in 1985

Currently, no Avro 707 models remain operational in flight. Both existing 707A units have been preserved: one, designated WZ736, was formerly housed at the Museum of Science and Industry in Manchester in the UK but has since been relocated to the Boscombe Down Aviation Collection at Old Sarum. The other, WD280, is maintained in Australia at the RAAF Museum located in Point Cook, Victoria. Additionally, the sole 707C prototype, WZ744, is preserved in the United Kingdom. It was displayed at the Royal Air Force Museum Midlands in Cosford near Wolverhampton, but it is now kept out of public view as its exhibition space has been reassigned to the British Aerospace EAP within the museum’s Test Flight gallery.

Operators

Template:AUS

• Royal Australian Air Force
• Aeronautical Research Laboratories

Template:UK

• Aeroplane and Armament Experimental Establishment
• Royal Aircraft Establishment

External links

• Aeroflight